WorldWideScience

Sample records for ii metallicity gradients

  1. A Novel 3D Printer to Support Additive Manufacturing of Gradient Metal Alloy Structures, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Gradient metal alloy structures possess multi-functional properties that conventional monolithic metal counterparts do not have. Such structures can potentially...

  2. Electric field gradients in metals

    International Nuclear Information System (INIS)

    Schatz, G.

    1979-01-01

    A review of the recent works on electric field gradient in metals is given. The main emphasis is put on the temperature dependence of the electric field gradient in nonmagnetic metals. Some methods of investigation of this effect using nuclear probes are described. One of them is nuclear accoustic resonance method. (S.B.)

  3. Supergiants and the Galactic metallicity gradient. II. Spectroscopic abundances for 64 distant F- to M-type supergiants

    International Nuclear Information System (INIS)

    Luck, R.E.; Bond, H.E.

    1989-01-01

    The metallicity gradient in the Galactic disk from in situ stars with visual magnitude ranging from 6 to 10 is analyzed. Atmospheric parameters and detailed chemical abundances for 64 Population I supergiants of spectral types F through M and luminosity classes Ia through II have been determined. The derived Fe/H ratios ranging from -0.5 to + 0.7 show a mean value of +0.13 with an estimated uncertainty of + or - 0.2. A subset of 25 supergiants fainter than 7th magnitude lying in the direction of the Galactic center shows a Fe/H mean of +0.18 + or - 0.04, while a similar sample of 15 faint supergiants lying in the direction of the Galactic anticenter shows a lower Fe/H mean of +0.07 + or - 0.06. For a sample of bright supergiants analyzed by Luck and Lambert (1985), the mean abundance pattern for all 64 stars showed the following: deficient C and O along with enhancement of N, indicating mixing of CNO-cycled material to the stellar surfaces; an apparent Sr enhancement attributed to departures from LTE; and an essentially solar pattern of other chemical elements. 50 refs

  4. Composition gradients across spiral galaxies II. The stellar mass limit

    International Nuclear Information System (INIS)

    Shields, G.A.; Tinsley, B.M.

    1976-01-01

    The equivalent width of the Hβ emission from H ii regions in spiral galaxies increases with distance from the nucleus. This W (Hβ) gradient is interpreted in terms of a radial gradient in the temperature of the hottest exciting stars. (T/subu/). From Searle's observations of M101, an increase Δ log T/subu/=0.02--0.13 from the intermediate to outermost spiral arms of M101 is inferred. There is also a radial decrease in the metal abundance (Z) across M101, and the T/subu/ gradient is consistent with the prediction of Kahn's recent theory that the upper mass limit for star formation should be smaller in regions of high Z. It is noted also that, even in the absence of changes in the upper mass limit, a T/subu/ gradient is expected because metal-rich stars of given mass have smaller effective temperatures. Several observational and theoretical improvements are needed before firm conclusions can be drawn, but it is clear that the presence of a T/subu/ gradient may lead to several important systematic changes in the interpretation of gradients in the properties of H ii regions across galaxies. A T/subu/ gradient reduces the Z gradient that is inferred from emission-line ratios, and it may help to explain why O ii is strong in the innermost regions where O iii is weak. A T/subu/ gradient may also partly camouflage a helium abundance gradient

  5. METALLICITY GRADIENTS OF THICK DISK DWARF STARS

    Energy Technology Data Exchange (ETDEWEB)

    Carrell, Kenneth; Chen Yuqin; Zhao Gang, E-mail: carrell@nao.cas.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2012-12-01

    We examine the metallicity distribution of the Galactic thick disk using F, G, and K dwarf stars selected from the Sloan Digital Sky Survey, Data Release 8. Using the large sample of dwarf stars with proper motions and spectroscopically determined stellar parameters, metallicity gradients in the radial direction for various heights above the Galactic plane and in the vertical direction for various radial distances from the Galaxy center have been found. In particular, we find a vertical metallicity gradient of -0.113 {+-} 0.010 (-0.125 {+-} 0.008) dex kpc{sup -1} using an isochrone (photometric) distance determination in the range 1 kpc <|Z| < 3 kpc, which is the vertical height range most consistent with the thick disk of our Galaxy. In the radial direction, we find metallicity gradients between +0.02 and +0.03 dex kpc{sup -1} for bins in the vertical direction between 1 kpc <|Z| < 3 kpc. Both of these results agree with similar values determined from other populations of stars, but this is the first time a radial metallicity gradient for the thick disk has been found at these vertical heights. We are also able to separate thin and thick disk stars based on kinematic and spatial probabilities in the vertical height range where there is significant overlap of these two populations. This should aid further studies of the metallicity gradients of the disk for vertical heights lower than those studied here but above the solar neighborhood. Metallicity gradients in the thin and thick disks are important probes into possible formation scenarios for our Galaxy and a consistent picture is beginning to emerge from results using large spectroscopic surveys, such as the ones presented here.

  6. Ternary gradient metal-organic frameworks.

    Science.gov (United States)

    Liu, Chong; Rosi, Nathaniel L

    2017-09-08

    Gradient MOFs contain directional gradients of either structure or functionality. We have successfully prepared two ternary gradient MOFs based on bMOF-100 analogues, namely bMOF-100/102/106 and bMOF-110/100/102, via cascade ligand exchange reactions. The cubic unit cell parameter discrepancy within an individual ternary gradient MOF crystal is as large as ∼1 nm, demonstrating the impressive compatibility and flexibility of the component MOF materials. Because of the presence of a continuum of unit cells, the pore diameters within individual crystals also change in a gradient fashion from ∼2.5 nm to ∼3.0 nm for bMOF-100/102/106, and from ∼2.2 nm to ∼2.7 nm for bMOF-110/100/102, indicating significant porosity gradients. Like previously reported binary gradient MOFs, the composition of the ternary gradient MOFs can be easily controlled by adjusting the reaction conditions. Finally, X-ray diffraction and microspectrophotometry were used to analyse fractured gradient MOF crystals by comparing unit cell parameters and absorbance spectra at different locations, thus revealing the profile of heterogeneity (i.e. gradient distribution of properties) and further confirming the formation of ternary gradient MOFs.

  7. Metallicity gradient of the thick disc progenitor at high redshift

    Science.gov (United States)

    Kawata, Daisuke; Allende Prieto, Carlos; Brook, Chris B.; Casagrande, Luca; Ciucă, Ioana; Gibson, Brad K.; Grand, Robert J. J.; Hayden, Michael R.; Hunt, Jason A. S.

    2018-01-01

    We have developed a novel Markov Chain Monte Carlo chemical 'painting' technique to explore possible radial and vertical metallicity gradients for the thick disc progenitor. In our analysis, we match an N-body simulation to the data from the Apache Point Observatory Galactic Evolution Experiment survey. We assume that the thick disc has a constant scaleheight and has completed its formation at an early epoch, after which time radial mixing of its stars has taken place. Under these assumptions, we find that the initial radial metallicity gradient of the thick disc progenitor should not be negative, but either flat or even positive, to explain the current negative vertical metallicity gradient of the thick disc. Our study suggests that the thick disc was built-up in an inside-out and upside-down fashion, and older, smaller and thicker populations are more metal poor. In this case, star-forming discs at different epochs of the thick disc formation are allowed to have different radial metallicity gradients, including a negative one, which helps to explain a variety of slopes observed in high-redshift disc galaxies. This scenario helps to explain the positive slope of the metallicity-rotation velocity relation observed for the Galactic thick disc. On the other hand, radial mixing flattens the slope of an existing gradient.

  8. Strain gradient plasticity effects in whisker-reinforced metals

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2002-01-01

    A metal reinforced by fibers in the micron range is studied using the strain gradient plasticity theory of Fleck and Hutchinson (2001). Cell-model analyzes are used to study the influence of the material length parameters numerically. Different higher order boundary conditions are considered...... at the fiber-matrix interface. The results are presented as overall stress-strain curves for the whisker-reinforced metal, and also contour plots of effective plastic strain are shown. The strain gradient plasticity theory predicts a significant stiffening effect when compared to conventional models...

  9. Strain gradient plasticity effects in whisker-reinforced metals

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2003-01-01

    A metal reinforced by fibers in the micron range is studied using the strain gradient plasticity theory of Fleck and Hutchinson (J. Mech. Phys. Solids 49 (2001) 2245). Cell-model analyses are used to study the influence of the material length parameters numerically, for both a single parameter...

  10. The Metallicity Gradient of the Old Galactic Bulge Population

    Science.gov (United States)

    Sans Fuentes, Sara Alejandra; De Ridder, Joris

    Understanding the structure, formation and evolution of the Galactic Bulge requires the proper determination of spatial metallicity gradients in both the radial and vertical directions. RR Lyrae pulsators, known to be excellent distance indicators, may hold the key to determining these gradients. Jurcsik and Kovacs (A&A 312:111, 1996) has shown that RR Lyrae light curves and the phase difference of their Fourier decomposition, ϕ 31, can be used to estimate photometric metallicities. The existence of galactic bulge metallicity gradients is a currently debated topic that would help pinpoint the Galaxy's formation and evolution. A recent study of the OGLE-III Galactic Bulge RR Lyrae Population by Pietrukowicz et al. (ApJ 750:169, 2012) suggests that the spatial distribution is uniform. We investigate how small a gradient would be detectable within the current S/N levels of the present data set, given the random and systematic errors associated with the derivation of a photometric metallicity versus spatial position relationship.

  11. Metal concentrations in urban riparian sediments along an urbanization gradient

    Science.gov (United States)

    Daniel J. Bain; Ian D. Yesilonis; Richard V. Pouyat

    2012-01-01

    Urbanization impacts fluvial systems via a combination of changes in sediment chemistry and basin hydrology. While chemical changes in urban soils have been well characterized, similar surveys of riparian sediments in urbanized areas are rare. Metal concentrations were measured in sediments collected from riparian areas across the urbanization gradient in Baltimore, MD...

  12. Responses of wild small mammals to a pollution gradient: Host factors influence metal and metallothionein levels

    International Nuclear Information System (INIS)

    Fritsch, Clementine; Cosson, Richard P.; Coeurdassier, Michael; Raoul, Francis; Giraudoux, Patrick; Crini, Nadia; Vaufleury, Annette de; Scheifler, Renaud

    2010-01-01

    We investigated how host factors (species, age, gender) modulated Cd, Pb, Zn, and Cu concentrations, metallothionein levels (MTs) and their relationships in 7 sympatric small mammal species along a pollution gradient. Cd concentrations in liver and kidneys increased with age in all species. Age effect on other metals and MTs differs among species. Gender did not influence metal and MT levels except in the bank vole. Three patterns linking internal metal concentrations and MTs were observed along the gradient: a low metal accumulation with a (i) high (wood mouse) or (ii) low (bank vole) level of MTs accompanied by a slight or no increase of MTs with Cd accumulation; (iii) an elevated metal accumulation with a sharp increase of MTs (common and pygmy shrews). In risk assessment and biomonitoring perspectives, we conclude that measurements of MTs and metals might be associated because they cannot be interpreted properly when considered separately. - Age more than gender and species more than trophic group influence metallic trace element and metallothionein levels and their relationships in wild small mammals exposed to metals.

  13. A Novel 3D Printer to Support Additive Manufacturing of Gradient Metal Alloy Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Gradient metal alloy structures possess multi-functional properties that conventional monolithic metal counterparts do not have. Such structures can potentially...

  14. Heavy Metal Diffusion through Soft Clay under High Hydraulic Gradients

    Directory of Open Access Journals (Sweden)

    Zaheer Ahmed Almani

    2013-04-01

    Full Text Available This study was focused on the determination of contaminant transport parameters of heavy metal Zinc moving through saturated soft Bangkok undisturbed clay under high hydraulic gradients. These parameters were compared with contaminant transport determined under concentration gradient alone (pure diffusion. In total fifteen column tests were conducted and a mathematical model was applied to determine the coefficients. Two different source concentrations conditions, constant and decreasing, were applied. Testing periods were ranged from 15-60 days while hydraulic gradients were ranged from 0-500. The curves between relative concentration and time and pore volume were developed for the constant source condition whereas curves between source reservoirs concentrations and time were developed for decreasing source condition. The effective diffusion and distribution coefficients, De and Kd, were determined by curve fitting using the computer code POLLUTE v 6.3. The results showed that diffusion coefficient increases and distribution coefficient decreases as hydraulic gradient increases from 0 to high value of 500 due to contribution of dispersion and additional molecular diffusion at high advective velocity. Thus, testing at high gradients ensures the safe performance of earthen barriers under worse conditions.

  15. Strain gradient drives shear banding in metallic glasses

    Science.gov (United States)

    Tian, Zhi-Li; Wang, Yun-Jiang; Chen, Yan; Dai, Lan-Hong

    2017-09-01

    Shear banding is a nucleation-controlled process in metallic glasses (MGs) involving multiple temporal-spatial scales, which hinders a concrete understanding of its structural origin down to the atomic scale. Here, inspired by the morphology of composite materials, we propose a different perspective of MGs as a hard particle-reinforced material based on atomic-scale structural heterogeneity. The local stable structures indicated by a high level of local fivefold symmetry (L5FS) act as hard "particles" which are embedded in the relatively soft matrix. We demonstrate this concept by performing atomistic simulations of shear banding in CuZr MG. A shear band is prone to form in a sample with a high degree of L5FS which is slowly quenched from the liquid. An atomic-scale analysis on strain and the structural evolution reveals that it is the strain gradient effect that has originated from structural heterogeneity that facilitates shear transformation zones (STZs) to mature shear bands. An artificial composite model with a high degree of strain gradient, generated by inserting hard MG strips into a soft MG matrix, demonstrates a great propensity for shear banding. It therefore confirms the critical role strain gradient plays in shear banding. The strain gradient effect on shear banding is further quantified with a continuum model and a mechanical instability analysis. These physical insights might highlight the strain gradient as the hidden driving force in transforming STZs into shear bands in MGs.

  16. Immunotoxicology in wood mice along a heavy metal pollution gradient

    International Nuclear Information System (INIS)

    Tersago, Katrien; De Coen, Wim; Scheirs, Jan; Vermeulen, Katrien; Blust, Ronny; Bockstaele, Dirk van; Verhagen, Ron

    2004-01-01

    We carried out an immunotoxicological field study of wood mice in three populations along a heavy metal pollution gradient. Heavy metal concentrations in liver tissue indicated that exposure to silver, arsenic, cadmium, cobalt and lead decreased with increasing distance from a non-ferrous smelter. Host resistance to the endoparasite Heligmosomoides polygyrus decreased with increasing exposure, while the abundance of tick larvae and the nematode Syphacia stroma was unrelated to heavy metal exposure. Spleen mass was increased at the intermediate and the most polluted sites and was positively correlated with the number of H. polygyrus and tick larvae. Proportion of early apoptotic leukocytes increased towards the smelter and was positively related to cadmium exposure. Red and white blood cell counts and lysozyme activity showed no relationship with metal exposure. All together, our observations suggest negative effects of heavy metal exposure on the immune function of wood mice under field conditions. - Capsule: Complex interactions among metal burden, immune response and parasite burden suggest negative effects of heavy metal exposure on the immune system of wood mice

  17. Generation of metal composition gradients by means of bipolar electrodeposition

    International Nuclear Information System (INIS)

    Tisserant, Gwendoline; Fattah, Zahra; Ayela, Cédric; Roche, Jérome; Plano, Bernard; Zigah, Dodzi; Goudeau, Bertrand; Kuhn, Alexander; Bouffier, Laurent

    2015-01-01

    Highlights: • A bipolar electrochemistry approach for the preparation of surface gradients is reported. • Several metals are simultaneously deposited on a bipolar electrode. • The elemental composition and thickness of the deposit varies alongside the bipolar electrode. • The deposit affects the surface properties and exhibits a barcode feature. - Abstract: Bipolar electrochemistry is an unconventional technique that currently encounters a renewal of interest due to modern applications in the fields of analytical chemistry or materials science. The approach is particularly relevant for the preparation of asymmetric objects or surfaces such as Janus particles for example. Bipolar electrochemistry allows spatially controlled deposition of various layers from electroactive precursors, selectively at one side of a bipolar electrode. We report here the concomitant cathodic deposition of up to three different metals at the same time in a single experiment. The deposits were characterized by optical and electron microscopy imaging as well as profilometry and energy dispersive X-ray spectroscopy. As a result, the deposited layer is composed of several areas exhibiting both a composition and a thickness gradient. Such a variation directly modifies the optical and electronic properties alongside the surface and gives access to the design of composite surfaces exhibiting a visual gradient feature.

  18. Extraterrestrial Metals Processing, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The Extraterrestrial Metals Processing (EMP) system produces iron, silicon, and light metals from Mars, Moon, or asteroid resources in support of advanced human...

  19. Diffusion and surface alloying of gradient nanostructured metals

    Directory of Open Access Journals (Sweden)

    Zhenbo Wang

    2017-03-01

    Full Text Available Gradient nanostructures (GNSs have been optimized in recent years for desired performance. The diffusion behavior in GNS metals is crucial for understanding the diffusion mechanism and relative characteristics of different interfaces that provide fundamental understanding for advancing the traditional surface alloying processes. In this paper, atomic diffusion, reactive diffusion, and surface alloying processes are reviewed for various metals with a preformed GNS surface layer. We emphasize the promoted atomic diffusion and reactive diffusion in the GNS surface layer that are related to a higher interfacial energy state with respect to those in relaxed coarse-grained samples. Accordingly, different surface alloying processes, such as nitriding and chromizing, have been modified significantly, and some diffusion-related properties have been enhanced. Finally, the perspectives on current research in this field are discussed.

  20. Lead (II) and nickel (II) adsorption kinetics from aqueous metal ...

    African Journals Online (AJOL)

    This paper discusses the kinetics of lead (II) and Nickel (II) ions adsorption from aqueous solutions using chemically modified and unmodified agricultural adsorbents at 28°C, pH 6.2 and 0.01M NaCl ionic strength. The removal of the two metals were found to increase with increase in chemical modification, the sequence ...

  1. THE ORIGIN AND EVOLUTION OF METALLICITY GRADIENTS: PROBING THE MODE OF MASS ASSEMBLY AT z ≅ 2

    International Nuclear Information System (INIS)

    Jones, Tucker; Ellis, Richard S.; Richard, Johan; Jullo, Eric

    2013-01-01

    We present and discuss measurements of the gas-phase metallicity gradient in four gravitationally lensed galaxies at z = 2.0-2.4 based on adaptive optics-assisted imaging spectroscopy with the Keck II telescope. Three galaxies with well-ordered rotation reveal metallicity gradients with lower gas-phase metallicities at larger galactocentric radii. Two of these display gradients much steeper than found locally, while a third has one similar to that seen in local disk galaxies. The fourth galaxy exhibits complex kinematics indicative of an ongoing merger and reveals an 'inverted' gradient with lower metallicity in the central regions. By comparing our sample to similar data in the literature for lower redshift galaxies, we determine that, on average, metallicity gradients must flatten by a factor of 2.6 ± 0.9 between z = 2.2 and the present epoch. This factor is in rough agreement with the size growth of massive galaxies, suggesting that inside-out growth can account for the evolution of metallicity gradients. Since the addition of our new data provides the first indication of a coherent picture of this evolution, we develop a simple model of chemical evolution to explain the collective data. We find that metallicity gradients and their evolution can be explained by the inward radial migration of gas together with a radial variation in the mass loading factor governing the ratio of outflowing gas to the local star formation rate. Average mass loading factors of ∼< 2 are inferred from our model in good agreement with direct measurements of outflowing gas in z ≅ 2 galaxies.

  2. Applications for Gradient Metal Alloys Fabricated Using Additive Manufacturing

    Science.gov (United States)

    Hofmann, Douglas C.; Borgonia, John Paul C.; Dillon, Robert P.; Suh, Eric J.; Mulder, jerry L.; Gardner, Paul B.

    2013-01-01

    assortment of "post-processing" methods to locally alter properties (such as coating, heat treating, work hardening, shot peening, etching, anodizing, among others). Building the final part in an additive process allows for the development of an entirely new class of metals, so-called "functionally graded metals" or "gradient alloys." By carefully blending feedstock materials with different properties in an AM process, hardware can be developed with properties that cannot be obtained using other techniques but with the added benefit of the net-shaped fabrication that AM allows.

  3. ASCA observation of NGC 4636: Dark matter and metallicity gradient

    Science.gov (United States)

    Mushotzky, R. F.; Loewenstein, M.; Awaki, H.; Makishima, K.; Matsushita, K.; Matsumoto, H.

    1994-01-01

    We present our analysis of ASCA PV phase observation of the elliptical galaxy NGC 4636. Solid state imaging spectrometer (SIS) spectra in six concentric annuli centered on NGC 4636 are used to derive temperature, metallicity, and column density profiles for the hot interstellar medium. Outside of the central 3 min the temperature is roughly constant at approximately 0.85 keV, while the metallicity decreases from greater than 0.36 solar at the center to less than 0.12 solar at R approximately 9 min. The implications of this gradient for elliptical galaxy formation and the enrichment of intracluster gas are discussed. We derive a detailed mass profile consistent with the stellar velocity dispersion and with ROSAT position sensitive proportional counter (PSPC) and ASCA SIS X-ray temperature profiles. We find that NGC 4636 becomes dark matter dominated at roughly the de Vaucouleurs radius, and, at r approximately 100 kpc, the ratio of dark to luminous matter density is approximately 80 and solar mass/solar luminosity approximately equal to 150. Evidence for the presence of a cooling flow is also discussed.

  4. SDSS-IV MaNGA: modelling the metallicity gradients of gas and stars - radially dependent metal outflow versus IMF

    Science.gov (United States)

    Lian, Jianhui; Thomas, Daniel; Maraston, Claudia; Goddard, Daniel; Parikh, Taniya; Fernández-Trincado, J. G.; Roman-Lopes, Alexandre; Rong, Yu; Tang, Baitian; Yan, Renbin

    2018-05-01

    In our previous work, we found that only two scenarios are capable of reproducing the observed integrated mass-metallicity relations for the gas and stellar components of local star-forming galaxies simultaneously. One scenario invokes a time-dependent metal outflow loading factor with stronger outflows at early times. The other scenario uses a time-dependent initial mass function (IMF) slope with a steeper IMF at early times. In this work, we extend our study to investigate the radial profile of gas and stellar metallicity in local star-forming galaxies using spatially resolved spectroscopic data from the SDSS-IV MaNGA survey. We find that most galaxies show negative gradients in both gas and stellar metallicity with steeper gradients in stellar metallicity. The stellar metallicity gradients tend to be mass dependent with steeper gradients in more massive galaxies while no clear mass dependence is found for the gas metallicity gradient. Then we compare the observations with the predictions from a chemical evolution model of the radial profiles of gas and stellar metallicities. We confirm that the two scenarios proposed in our previous work are also required to explain the metallicity gradients. Based on these two scenarios, we successfully reproduce the radial profiles of gas metallicity, stellar metallicity, stellar mass surface density, and star formation rate surface density simultaneously. The origin of the negative gradient in stellar metallicity turns out to be driven by either radially dependent metal outflow or IMF slope. In contrast, the radial dependence of the gas metallicity is less constrained because of the degeneracy in model parameters.

  5. Interior Gradient Estimates for Nonuniformly Parabolic Equations II

    Directory of Open Access Journals (Sweden)

    Lieberman Gary M

    2007-01-01

    Full Text Available We prove interior gradient estimates for a large class of parabolic equations in divergence form. Using some simple ideas, we prove these estimates for several types of equations that are not amenable to previous methods. In particular, we have no restrictions on the maximum eigenvalue of the coefficient matrix and we obtain interior gradient estimates for so-called false mean curvature equation.

  6. Gradient porous electrode architectures for rechargeable metal-air batteries

    Science.gov (United States)

    Dudney, Nancy J.; Klett, James W.; Nanda, Jagjit; Narula, Chaitanya Kumar; Pannala, Sreekanth

    2016-03-22

    A cathode for a metal air battery includes a cathode structure having pores. The cathode structure has a metal side and an air side. The porosity decreases from the air side to the metal side. A metal air battery and a method of making a cathode for a metal air battery are also disclosed.

  7. Photodetachment of negative ion in a gradient electric field near a metal surface

    International Nuclear Information System (INIS)

    Liu Tian-Qi; Wang De-Hua; Han Cai; Liu Jiang; Liang Dong-Qi; Xie Si-Cheng

    2012-01-01

    Based on closed-orbit theory, the photodetachment of H − in a gradient electric field near a metal surface is studied. It is demonstrated that the gradient electric field has a significant influence on the photodetachment of negative ions near a metal surface. With the increase of the gradient of the electric field, the oscillation in the photodetachment cross section becomes strengthened. Besides, in contrast to the photodetachment of H − near a metal surface in a uniform electric field, the oscillating amplitude and the oscillating region in the cross section of a gradient electric field also become enlarged. Therefore, we can use the gradient electric field to control the photodetachment of negative ions near a metal surface. We hope that our results will be useful for understanding the photodetachment of negative ions in the vicinity of surfaces, cavities, and ion traps. (atomic and molecular physics)

  8. Accumulation and effects of metals in caged carp and resident roach along a metal pollution gradient

    International Nuclear Information System (INIS)

    Reynders, H.; Bervoets, L.; Gelders, M.; Coen, W.M. de; Blust, R.

    2008-01-01

    Metal accumulation and effects on plasma Ca 2+ , alanine transaminase (ALT) and fish condition factor were examined in caged carp (Cyprinus carpio) and resident roach (Rutilus rutilus) at four locations along the Grote Nete River system (Belgium). Cadmium and zinc accumulation were found in carp and roach, with highest concentrations at the most contaminated site (dissolved Cd: 1.82 μg/l, Zn: 967 μg/l). On the tissue level, highest cadmium concentrations were measured in kidneys of carp and roach, followed by gills, intestine and liver, while low concentrations were observed in carcass and muscle. For zinc, a similar pattern was observed (intestine > kidney > gills > liver > carcass > muscle). Comparison between species showed higher cadmium concentrations in feral roach, while zinc levels were lower, owing to the high zinc concentrations in control carp. Furthermore, comparison of metal concentrations between two sampling periods (2005 and 2000-2001) revealed a drastic decrease in cadmium concentration in gills, liver and muscle of roach, similar to the reduction in waterborne cadmium concentrations, while differences for zinc were much less pronounced. In addition to metal accumulation, increased metallothionein concentrations (∼ 2x) were found in carp and roach, while no metal-related effects were found on ALT, Ca 2+ or condition factor. However, negative effects on fish community structure, as assessed by the index of biotic integrity (IBI), were found along the pollution gradient and indicated long-term adverse effects of metal pollution

  9. Accumulation and effects of metals in caged carp and resident roach along a metal pollution gradient

    Energy Technology Data Exchange (ETDEWEB)

    Reynders, H. [Department of Biology, Research Unit Ecophysiology, Biochemistry and Toxicology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)], E-mail: hans.reynders@ua.ac.be; Bervoets, L.; Gelders, M.; Coen, W.M. de; Blust, R. [Department of Biology, Research Unit Ecophysiology, Biochemistry and Toxicology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2008-02-25

    Metal accumulation and effects on plasma Ca{sup 2+}, alanine transaminase (ALT) and fish condition factor were examined in caged carp (Cyprinus carpio) and resident roach (Rutilus rutilus) at four locations along the Grote Nete River system (Belgium). Cadmium and zinc accumulation were found in carp and roach, with highest concentrations at the most contaminated site (dissolved Cd: 1.82 {mu}g/l, Zn: 967 {mu}g/l). On the tissue level, highest cadmium concentrations were measured in kidneys of carp and roach, followed by gills, intestine and liver, while low concentrations were observed in carcass and muscle. For zinc, a similar pattern was observed (intestine > kidney > gills > liver > carcass > muscle). Comparison between species showed higher cadmium concentrations in feral roach, while zinc levels were lower, owing to the high zinc concentrations in control carp. Furthermore, comparison of metal concentrations between two sampling periods (2005 and 2000-2001) revealed a drastic decrease in cadmium concentration in gills, liver and muscle of roach, similar to the reduction in waterborne cadmium concentrations, while differences for zinc were much less pronounced. In addition to metal accumulation, increased metallothionein concentrations ({approx} 2x) were found in carp and roach, while no metal-related effects were found on ALT, Ca{sup 2+}or condition factor. However, negative effects on fish community structure, as assessed by the index of biotic integrity (IBI), were found along the pollution gradient and indicated long-term adverse effects of metal pollution.

  10. Contribution of trace metals in structuring in situ macroinvertebrate community composition along a salinity gradient

    NARCIS (Netherlands)

    Peeters, E.T.H.M.; Gardeniers, J.J.P.; Koelmans, A.A.

    2000-01-01

    Macroinvertebrates were studied along a salinity gradient in the North Sea Canal, The Netherlands, to quantify the effect of trace metals (cadmium, copper, lead, zinc) on community composition. In addition, two methods for assessing metal bioavailability (normalizing metal concentrations on organic

  11. The stellar metallicity gradients in galaxy discs in a cosmological scenario

    Science.gov (United States)

    Tissera, Patricia B.; Machado, Rubens E. G.; Sanchez-Blazquez, Patricia; Pedrosa, Susana E.; Sánchez, Sebastián F.; Snaith, Owain; Vilchez, Jose

    2016-08-01

    Context. The stellar metallicity gradients of disc galaxies provide information on disc assembly, star formation processes, and chemical evolution. They also might store information on dynamical processes that could affect the distribution of chemical elements in the gas phase and the stellar components. Understanding their joint effects within a hierarchical clustering scenario is of paramount importance. Aims: We studied the stellar metallicity gradients of simulated discs in a cosmological simulation. We explored the dependence of the stellar metallicity gradients on stellar age and on the size and mass of the stellar discs. Methods: We used a catalogue of galaxies with disc components selected from a cosmological hydrodynamical simulation performed including a physically motivated supernova feedback and chemical evolution. Disc components were defined based on angular momentum and binding energy criteria. The metallicity profiles were estimated for stars with different ages. We confront our numerical findings with results from the Calar Alto Legacy Integral Field Area (CALIFA) Survey. Results: The simulated stellar discs are found to have metallicity profiles with slopes in global agreement with observations. Low stellar mass galaxies tend to have a larger variety of metallicity slopes. When normalized by the half-mass radius, the stellar metallicity gradients do not show any dependence and the dispersion increases significantly, regardless of the galaxy mass. Galaxies with stellar masses o f around 1010M⊙ show steeper negative metallicity gradients. The stellar metallicity gradients correlate with the half-mass radius. However, the correlation signal is not present when they are normalized by the half-mass radius. Stellar discs with positive age gradients are detected to have negative and positive metallicity gradients, depending on the relative importance of recent star formation activity in the central regions. Conclusions: Our results suggest that inside

  12. On the homogenization of metal matrix composites using strain gradient plasticity

    DEFF Research Database (Denmark)

    Azizi, Reza; Niordson, Christian Frithiof; Legarth, Brian Nyvang

    2014-01-01

    The homogenized response of metal matrix composites (MMC) is studied using strain gradient plasticity. The material model employed is a rate independent formulation of energetic strain gradient plasticity at the micro scale and conventional rate independent plasticity at the macro scale. Free...

  13. Design of the Zero Gradient Synchrotron Booster-II lattice

    International Nuclear Information System (INIS)

    Crosbie, E.A.; Foss, M.H.; Khoe, T.K.; Simpson, J.D.

    1975-01-01

    A 500 MeV booster was designed at the Argonne National Laboratory to increase the beam intensity from the Zero Gradient Synchrotron (ZGS). Many turns of H - ions from the 50 MeV linac will be injected into the booster and stripped to H + so that the ring will contain the maximum useful charge in each booster pulse. Several booster pulses will be injected into the ZGS to form one ZGS pulse. This machine is now under construction. (auth)

  14. Transfer and accumulation of metals in a soil-diet-wood mouse food chain along a metal pollution gradient

    International Nuclear Information System (INIS)

    Rogival, Damien; Scheirs, Jan; Blust, Ronny

    2007-01-01

    We studied the accumulation and transfer of As, Cd, Cu, Pb and Zn in the compartments of a soil-diet-wood mouse (Apodemus sylvaticus) food chain at five sites located along a metal pollution gradient. We observed a clear gradient in metal exposure at increasing distance from the smelter in all compartments of the food chain for the non-essential metals. The gradient was less clear or absent for the essential metals in acorn and mice target tissues. Regression analysis showed overall strong relationships within the soil-diet and diet-wood mouse compartments for the non-essential metals, while relationships for the essential metals were weak or absent. Total metal in soil appeared as a better predictor for the diet metal content than the available metal fraction. Our results suggest a more important transfer of non-essential elements through the food chain than essential elements, which is probably a consequence of homeostatic control of the latter group. - Non-essential metal transfer through a soil-diet-wood mouse food chain is more important than essential metal transfer

  15. 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

  16. Computational modeling applied to stress gradient analysis for metallic alloys

    International Nuclear Information System (INIS)

    Iglesias, Susana M.; Assis, Joaquim T. de; Monine, Vladimir I.

    2009-01-01

    Nowadays composite materials including materials reinforced by particles are the center of the researcher's attention. There are problems with the stress measurements in these materials, connected with the superficial stress gradient caused by the difference of the stress state of particles on the surface and in the matrix of the composite material. Computer simulation of diffraction profile formed by superficial layers of material allows simulate the diffraction experiment and gives the possibility to resolve the problem of stress measurements when the stress state is characterized by strong gradient. The aim of this paper is the application of computer simulation technique, initially developed for homogeneous materials, for diffraction line simulation of composite materials and alloys. Specifically we applied this technique for siluminum fabricated by powder metallurgy. (author)

  17. Subcellular partitioning of metals in Aporrectodea caliginosa along a gradient of metal exposure in 31 field-contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Beaumelle, Léa [INRA, UR 251 PESSAC, 78026 Versailles Cedex (France); Gimbert, Frédéric [Laboratoire Chrono-Environnement, UMR 6249 University of Franche-Comté/CNRS Usc INRA, 16 route de Gray, 25030 Besançon Cedex (France); Hedde, Mickaël [INRA, UR 251 PESSAC, 78026 Versailles Cedex (France); Guérin, Annie [INRA, US 0010 LAS Laboratoire d' analyses des sols, 273 rue de Cambrai, 62000 Arras (France); Lamy, Isabelle, E-mail: lamy@versailles.inra.fr [INRA, UR 251 PESSAC, 78026 Versailles Cedex (France)

    2015-07-01

    Subcellular fractionation of metals in organisms was proposed as a better way to characterize metal bioaccumulation. Here we report the impact of a laboratory exposure to a wide range of field-metal contaminated soils on the subcellular partitioning of metals in the earthworm Aporrectodea caliginosa. Soils moderately contaminated were chosen to create a gradient of soil metal availability; covering ranges of both soil metal contents and of several soil parameters. Following exposure, Cd, Pb and Zn concentrations were determined both in total earthworm body and in three subcellular compartments: cytosolic, granular and debris fractions. Three distinct proxies of soil metal availability were investigated: CaCl{sub 2}-extractable content dissolved content predicted by a semi-mechanistic model and free ion concentration predicted by a geochemical speciation model. Subcellular partitionings of Cd and Pb were modified along the gradient of metal exposure, while stable Zn partitioning reflected regulation processes. Cd subcellular distribution responded more strongly to increasing soil Cd concentration than the total internal content, when Pb subcellular distribution and total internal content were similarly affected. Free ion concentrations were better descriptors of Cd and Pb subcellular distribution than CaCl{sub 2} extractable and dissolved metal concentrations. However, free ion concentrations and soil total metal contents were equivalent descriptors of the subcellular partitioning of Cd and Pb because they were highly correlated. Considering lowly contaminated soils, our results raise the question of the added value of three proxies of metal availability compared to soil total metal content in the assessment of metal bioavailability to earthworm. - Highlights: • Earthworms were exposed to a wide panel of historically contaminated soils • Subcellular partitioning of Cd, Pb and Zn was investigated in earthworms • Three proxies of soil metal availability were

  18. Electromagnetic Detection of Stress Gradients at the Surfaces of Metals

    International Nuclear Information System (INIS)

    Schmidt, William F.; Zinke, Otto H.

    2004-01-01

    A general, integral expression is developed which relates measurements of the variations of the imaginary component of complex- reluctance with frequency to stress profiles near the surfaces of metals. The technique should yield either applied or residual stress profiles produced, for example, by heat-treating, metal-working, fatigue, or peening. It may even be applicable to carburizing. The technique of measurement cancels out the effects of any pre-treatment residual-stress profile (subject to the assumption of superposition). The general, integral expression is induced from the results of measurements on a steel bar which is subjected to both tensile tests and bending tests

  19. One Dimension Analytical Model of Normal Ballistic Impact on Ceramic/Metal Gradient Armor

    International Nuclear Information System (INIS)

    Liu Lisheng; Zhang Qingjie; Zhai Pengcheng; Cao Dongfeng

    2008-01-01

    An analytical model of normal ballistic impact on the ceramic/metal gradient armor, which is based on modified Alekseevskii-Tate equations, has been developed. The process of gradient armour impacted by the long rod can be divided into four stages in this model. First stage is projectile's mass erosion or flowing phase, mushrooming phase and rigid phase; second one is the formation of comminuted ceramic conoid; third one is the penetration of gradient layer and last one is the penetration of metal back-up plate. The equations of third stage have been advanced by assuming the behavior of gradient layer as rigid-plastic and considering the effect of strain rate on the dynamic yield strength

  20. One Dimension Analytical Model of Normal Ballistic Impact on Ceramic/Metal Gradient Armor

    Science.gov (United States)

    Liu, Lisheng; Zhang, Qingjie; Zhai, Pengcheng; Cao, Dongfeng

    2008-02-01

    An analytical model of normal ballistic impact on the ceramic/metal gradient armor, which is based on modified Alekseevskii-Tate equations, has been developed. The process of gradient armour impacted by the long rod can be divided into four stages in this model. First stage is projectile's mass erosion or flowing phase, mushrooming phase and rigid phase; second one is the formation of comminuted ceramic conoid; third one is the penetration of gradient layer and last one is the penetration of metal back-up plate. The equations of third stage have been advanced by assuming the behavior of gradient layer as rigid-plastic and considering the effect of strain rate on the dynamic yield strength.

  1. Risk assessment of metals in road-deposited sediment along an urban–rural gradient

    International Nuclear Information System (INIS)

    Zhao, Hongtao; Li, Xuyong

    2013-01-01

    We applied the traditional risk assessment methods originally designed for soils and river sediments to evaluation of risk associated with metals in road-deposited sediment (RDS) along an urban–rural gradient that included central urban (UCA), urban village (UVA), central suburban county (CSA), rural town (RTA), and rural village (RVA) areas in the Beijing metropolitan region. A new indicator RI RDS was developed which integrated the RDS characteristics of mobility, grain size and amount with the potential ecological risk index. The risk associated with metals in RDS in urban areas was generally higher than that in rural areas based on the assessment using traditional methods, but the risk was higher in urban and rural village areas than the areas with higher administration units based on the indicator RI RDS . These findings implied that RDS characteristics variation with the urban–rural gradient must be considered in metal risk assessment and RDS washoff pollution control. Highlights: ► Spatial pattern of metal risk level associated with road-deposited sediment (RDS) along urban–rural gradients varied. ► Risk level of metals changed significantly when grain size was considered. ► A new index integrating RDS characteristics and potential ecological risk was developed. ► Results from the new index were improved relative to those of traditional assessment methods. -- A new index integrating road-deposited sediment characteristics and potential ecological risk was developed to assess metal risk along the urban–rural gradient

  2. First-principles calculation of electric field gradients in metals, semiconductors, and insulators

    Energy Technology Data Exchange (ETDEWEB)

    Zwanziger, J.W. [Dalhousie Univ, Dept Chem, Halifax, NS (Canada); Dalhousie Univ, Inst Res Mat, Halifax, NS (Canada); Torrent, M. [CEA Bruyeres-le-Chatel, Dept Phys Theor and Appl, Bruyeres 91 (France)

    2008-07-01

    A scheme for computing electric field gradients within the projector augmented wave (PAW) formalism of density functional theory is presented. On the basis of earlier work (M. Profeta, F. Mauri, C.J. Pickard, J. Am. Chem. Soc. 125, 541, 2003) the present implementation handles metallic cases as well as insulators and semiconductors with equal efficiency. Details of the implementation, as well as applications and the discussion of the limitations of the PAW method for computing electric field gradients are presented. (authors)

  3. Interaction of Cr (III), Ni (II), Pb (II) with DTPA complexes of essential metal ions

    International Nuclear Information System (INIS)

    Gulzar, S.; Zahida; Maqsood, T.; Naqvi, R.R.

    2002-01-01

    With the increase of anthropogenic activities in the environment, heavy metal toxicity (Chromium, Nickel and Lead) is more common now. DTPA (diethylene triamine pentaacetic acid) a polyamino carboxylic acid is widely used to form hydrophilic and stable complexes with most of the metal ions. In this spectrophotometric study, concentration of Cr(III), Ni(II) and Pb(II) (toxic metal ions) exchanged with Fe(III), Zn(II) and Ca(II) from their DTPA complexes were estimated at pH 4,7 and 9. Concentration of added metal was varied from 1-4 times to that of complexed metal. (author)

  4. [Distribution characteristics of heavy metals along an elevation gradient of montane forest].

    Science.gov (United States)

    Wan, Jia-rong; Nie, Ming; Zou, Qin; Hu, Shao-chang; Chen, Jia-kuan

    2011-12-01

    In the present paper, the concentrations of fourteen heavy metals (Fe, Al, Ti, Cu, Cr, Mn, V, Zn, Ni, Co, Pb, Se, Cd and As) were determined by ICP-AES and atomic absorption spectroscopy along an elevation gradient of montane forest. The results show that the elevation gradient had significant effects on the concentrations of Fe, Al, Ti, V, Pb and As. And the concentrations of Cu, Cr, Mn, Zn, Ni, Co, Se and Cd were not significantly affected by the elevation gradient. Because the studying area is red soil, the elevation gradient had significant effects on the concentrations of Fe, Al and Ti which are characteristic heavy metals of red soil, suggesting that the red soil at different elevations has different intensities of weathering desilication and bioaccumulation. Other heavy metals have different relationships with the elevation gradient, such as the concentrations of Cr, Zn and Cd were high at relatively high elevation and Pb and As were high at relatively low elevation. These results suggest that the different elevations of montane forest soils were polluted by differently types of heavy metals.

  5. 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.

  6. Engineering zonal cartilage through bioprinting collagen type II hydrogel constructs with biomimetic chondrocyte density gradient.

    Science.gov (United States)

    Ren, Xiang; Wang, Fuyou; Chen, Cheng; Gong, Xiaoyuan; Yin, Li; Yang, Liu

    2016-07-20

    Cartilage tissue engineering is a promising approach for repairing and regenerating cartilage tissue. To date, attempts have been made to construct zonal cartilage that mimics the cartilaginous matrix in different zones. However, little attention has been paid to the chondrocyte density gradient within the articular cartilage. We hypothesized that the chondrocyte density gradient plays an important role in forming the zonal distribution of extracellular matrix (ECM). In this study, collagen type II hydrogel/chondrocyte constructs were fabricated using a bioprinter. Three groups were created according to the total cell seeding density in collagen type II pre-gel: Group A, 2 × 10(7) cells/mL; Group B, 1 × 10(7) cells/mL; and Group C, 0.5 × 10(7) cells/mL. Each group included two types of construct: one with a biomimetic chondrocyte density gradient and the other with a single cell density. The constructs were cultured in vitro and harvested at 0, 1, 2, and 3 weeks for cell viability testing, reverse-transcription quantitative PCR (RT-qPCR), biochemical assays, and histological analysis. We found that total ECM production was positively correlated with the total cell density in the early culture stage, that the cell density gradient distribution resulted in a gradient distribution of ECM, and that the chondrocytes' biosynthetic ability was affected by both the total cell density and the cell distribution pattern. Our results suggested that zonal engineered cartilage could be fabricated by bioprinting collagen type II hydrogel constructs with a biomimetic cell density gradient. Both the total cell density and the cell distribution pattern should be optimized to achieve synergistic biological effects.

  7. Why do disk galaxies present a common gas-phase metallicity gradient?

    Science.gov (United States)

    Chang, R.; Zhang, Shuhui; Shen, Shiyin; Yin, Jun; Hou, Jinliang

    2017-03-01

    CALIFA data show that isolated disk galaxies present a common gas-phase metallicity gradient, with a characteristic slope of -0.1dex/re between 0.3 and 2 disk effective radius re (Sanchez et al. 2014). Here we construct a simple model to investigate which processes regulate the formation and evolution.

  8. Advanced Gradient Based Optimization Techniques Applied on Sheet Metal Forming

    International Nuclear Information System (INIS)

    Endelt, Benny; Nielsen, Karl Brian

    2005-01-01

    The computational-costs for finite element simulations of general sheet metal forming processes are considerable, especially measured in time. In combination with optimization, the performance of the optimization algorithm is crucial for the overall performance of the system, i.e. the optimization algorithm should gain as much information about the system in each iteration as possible. Least-square formulation of the object function is widely applied for solution of inverse problems, due to the superior performance of this formulation.In this work focus will be on small problems which are defined as problems with less than 1000 design parameters; as the majority of real life optimization and inverse problems, represented in literature, can be characterized as small problems, typically with less than 20 design parameters.We will show that the least square formulation is well suited for two classes of inverse problems; identification of constitutive parameters and process optimization.The scalability and robustness of the approach are illustrated through a number of process optimizations and inverse material characterization problems; tube hydro forming, two step hydro forming, flexible aluminum tubes, inverse identification of material parameters

  9. Oribatid mite communities and metal bioaccumulation in oribatid species (Acari, Oribatida) along the heavy metal gradient in forest ecosystems

    International Nuclear Information System (INIS)

    Skubala, Piotr; Kafel, Alina

    2004-01-01

    The responses of oribatid communities to heavy metal contamination were studied. Concentration of cadmium, copper and zinc in nine oribatid species along a gradient of heavy metal pollution was measured. Oribatid mites were sampled seasonally during two years in five forests located at different distances from the zinc smelter in the Olkusz District, southern Poland. The most numerous and diverse oribatid communities were found in the forest with moderate concentrations of heavy metals. Analysis by atomic absorption spectrophotometry revealed large differences in metal body burdens among species. All studied oribatid species appeared to be accumulators of copper with Oppiella nova, Nothrus silvestris and Adoristes ovatus characterized by the highest bioaccumulation factors. Most species poorly accumulate cadmium and zinc. The accumulation of heavy metals in the body of oribatids was not strictly determined by their body size or the trophic level at which they operate

  10. SDSS IV MaNGA - metallicity and nitrogen abundance gradients in local galaxies

    Science.gov (United States)

    Belfiore, Francesco; Maiolino, Roberto; Tremonti, Christy; Sánchez, Sebastian F.; Bundy, Kevin; Bershady, Matthew; Westfall, Kyle; Lin, Lihwai; Drory, Niv; Boquien, Médéric; Thomas, Daniel; Brinkmann, Jonathan

    2017-07-01

    We study the gas phase metallicity (O/H) and nitrogen abundance gradients traced by star-forming regions in a representative sample of 550 nearby galaxies in the stellar mass range 109-1011.5 M⊙ with resolved spectroscopic data from the Sloan Digital Sky Survey IV Mapping Nearby Galaxies at Apache Point Observatory survey. Using strong-line ratio diagnostics (R23 and O3N2 for metallicity and N2O2 for N/O) and referencing to the effective (half-light) radius (Re), we find that the metallicity gradient steepens with stellar mass, lying roughly flat among galaxies with log (M⋆/M⊙) = 9.0 but exhibiting slopes as steep as -0.14 dex R_e^{-1} at log (M⋆/M⊙) = 10.5 (using R23, but equivalent results are obtained using O3N2). At higher masses, these slopes remain typical in the outer regions of our sample (R > 1.5Re), but a flattening is observed in the central regions (R 2.0Re), we detect a mild flattening of the metallicity gradient in stacked profiles, although with low significance. The N/O ratio gradient provides complementary constraints on the average chemical enrichment history. Unlike the oxygen abundance, the average N/O profiles do not flatten out in the central regions of massive galaxies. The metallicity and N/O profiles both depart significantly from an exponential form, suggesting a disconnect between chemical enrichment and stellar mass surface density on local scales. In the context of inside-out growth of discs, our findings suggest that central regions of massive galaxies today have evolved to an equilibrium metallicity, while the nitrogen abundance continues to increase as a consequence of delayed secondary nucleosynthetic production.

  11. Haematological status of wintering great tits (Parus major) along a metal pollution gradient

    Energy Technology Data Exchange (ETDEWEB)

    Geens, Ann, E-mail: ann.geens@ua.ac.be [Department of Biology, University of Antwerp, Ethology, Universiteitsplein 1, B-2610 Antwerp (Belgium); Dauwe, Tom [Department of Biology, University of Antwerp, Ethology, Universiteitsplein 1, B-2610 Antwerp (Belgium); VITO, Boeretang 200, B-2400 Mol (Belgium); Bervoets, Lieven; Blust, Ronny [Department of Biology, University of Antwerp, Ecophysiology, Biochemistry and Toxicology, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Eens, Marcel [Department of Biology, University of Antwerp, Ethology, Universiteitsplein 1, B-2610 Antwerp (Belgium)

    2010-02-01

    In the long-term biomonitoring of wild populations inhabiting polluted areas, the use of non-destructive biomarkers as markers of condition is very important. We examined the possible effects of metal pollution on the haematological status of adult great tits (Parus major) along a well-established pollution gradient near a non-ferrous smelter in Belgium. We measured blood and feather metal concentrations and assessed the haematological status (amount of red blood cells, haemoglobin concentration, haematocrit, mean corpuscular volume and mean corpuscular haemoglobin) of adult great tits during winter at four study sites. Metal concentrations in blood and feathers indicated that cadmium and lead were the most important metals in the pollution gradient under study. Measurements of haematological parameters revealed that haemoglobin concentration, haematocrit, mean corpuscular volume and mean corpuscular haemoglobin were lower in great tits from the more polluted sites. These parameters were significantly negatively correlated with blood lead concentration. The amount of red blood cells, however, did not significantly differ among study sites. Our results indicate that the haematological status of great tits is negatively affected by metal pollution and may therefore be used as a successful biomarker for monitoring the negative impact of metal exposure in the wild.

  12. Lightweight Metal RubberTM Sensors and Interconnects, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this NASA Phase II program is to develop and increase the Technology Readiness Level of multifunctional Metal RubberTM (MRTM) materials that can be...

  13. Elevational and Spatial Gradients of Atmospheric Metal Pollution in the North Pacific

    Science.gov (United States)

    Jongebloed, U. A.; Osterberg, E. C.; Kreutz, K. J.; Ferris, D. G.; Campbell, S.; Saylor, P. L.; Winski, D.; Handley, M.

    2017-12-01

    The industrial revolution has led to a several-fold increase in the atmospheric concentrations of heavy metals and metalloids including Pb, Cd, Cu, Zn, Hg and As. Modern emissions inventories identify Asia as the largest emitter of many of these toxic pollutants, which are subsequently transported eastwards across the North Pacific Ocean by prevailing westerly winds in the mid-upper troposphere. Previous ice cores collected from the Yukon Territory in the eastern North Pacific reveal evolution-dependent metal pollution histories; the highest (5300 m elevation) core from Mt. Logan records a nearly pure trans-Pacific Asian pollution record, whereas cores from lower sites like the Eclipse Icefield (3017 m) record a complex combination of Asian and more local North American emission. However, it is unclear if this elevation gradient of pollution sources is found in other regions of the North Pacific. Furthermore, the previous ice core records end in the late 1990's, before efforts by some Asian nations to reduce metal pollution, and it is unknown if North Pacific atmospheric metal concentrations have declined in response to these efforts. Here we investigate metal and metalloid concentrations and sources recorded in ice core and snow pit samples recovered from a vertical transect spanning 2200 - 5242 m within Denali National Park in the Central Alaska Range. We compare these metal concentrations and crustal enrichment factors to data from the Yukon Territory to investigate North Pacific regional metal gradients. We also present preliminary results from a new 60 m ice core from the Eclipse Icefield to evaluate recent trends in metal concentrations since the end of the Mt. Logan and original Eclipse records in 1998, and compare this to the recent metal pollution history recorded in the 2013 Denali Ice Core collected from the summit plateau (3900 m) of Mt. Hunter.

  14. Solar photocatalytic removal of Cu(II), Ni(II), Zn(II) and Pb(II): Speciation modeling of metal-citric acid complexes

    International Nuclear Information System (INIS)

    Kabra, Kavita; Chaudhary, Rubina; Sawhney, R.L.

    2008-01-01

    The present study is targeted on solar photocatalytic removal of metal ions from wastewater. Photoreductive deposition and dark adsorption of metal ions Cu(II), Ni(II), Pb(II) and Zn(II), using solar energy irradiated TiO 2 , has been investigated. Citric acid has been used as a hole scavenger. Modeling of metal species has been performed and speciation is used as a tool for discussing the photodeposition trends. Ninety-seven percent reductive deposition was obtained for copper. The deposition values of other metals were significantly low [nickel (36.4%), zinc (22.2%) and lead (41.4%)], indicating that the photocatalytic treatment process, using solar energy, was more suitable for wastewater containing Cu(II) ions. In absence of citric acid, the decreasing order deposition was Cu(II) > Ni(II) > Pb(II) > Zn(II), which proves the theoretical thermodynamic predictions about the metals

  15. Heavy metals in ordinary chernozems on slopes of different gradients and aspects

    Science.gov (United States)

    Dubovik, D. V.; Dubovik, E. V.

    2016-01-01

    The impact of slope aspect and gradient on the contents and distribution of heavy metals (Mn, Cu, Zn, Co, Ni, Pb, and Cd) in the profiles of ordinary chernozem (Haplic Chernozems) was studied in Kursk oblast. Slope aspect was found to be a significant factor controlling the distribution of most of the bulk, mobile, and acid-soluble compounds of heavy metals, whereas the position on the slope (slope gradient) did not exert a significant influence on the distribution of elements. Bulk compounds of Co, Ni, Pb, and Cd showed the eluvial type of distribution in the soil profiles along with accumulation in the lower horizons. Distribution patterns of the mobile Cu, Co, Ni, Pb, and Cd were similar to those of the bulk ones. The latter phenomenon may be attributed to the high content of carbonates, an increased content of clay, and some alkalization of the soil solution in the lower horizons.

  16. Gradient composite metal-ceramic foam as supportive component for planar SOFCs and MIEC membranes

    International Nuclear Information System (INIS)

    Smorygo, Oleg; Mikutski, Vitali; Marukovich, Alexander; Sadykov, Vladislav; Usoltsev, Vladimir; Mezentseva, Natalia; Borodinecs, Anatolijs; Bobrenok, Oleg

    2011-01-01

    A novel approach to the design of planar gradient porous supports for the thin-film SOFCs and MIEC membranes is described. The support's thermal expansion is controlled by the creation of a two-component composite metal-ceramic foam structure. Thin MIEC membranes and SOFCs were prepared on the composite supports by the layerwise deposition of composite functional layers including complex fluorites and perovskites. Lab-scale studies demonstrated promising performance of both MIEC membrane and SOFC.

  17. Gradient composite metal-ceramic foam as supportive component for planar SOFCs and MIEC membranes

    Science.gov (United States)

    Smorygo, Oleg; Mikutski, Vitali; Marukovich, Alexander; Sadykov, Vladislav; Usoltsev, Vladimir; Mezentseva, Natalia; Borodinecs, Anatolijs; Bobrenok, Oleg

    2011-06-01

    A novel approach to the design of planar gradient porous supports for the thin-film SOFCs and MIEC membranes is described. The support's thermal expansion is controlled by the creation of a two-component composite metal-ceramic foam structure. Thin MIEC membranes and SOFCs were prepared on the composite supports by the layerwise deposition of composite functional layers including complex fluorites and perovskites. Lab-scale studies demonstrated promising performance of both MIEC membrane and SOFC.

  18. High Resolution Studies Of Lensed z ∼ 2 Galaxies: Kinematics And Metal Gradients

    Science.gov (United States)

    Leethochawalit, Nicha

    2016-09-01

    We use the OSIRIS integral field unit (IFU) spectograph to secure spatially-resolved strong emission lines of 15 gravitationally-lensed star-forming galaxies at redshift z ∼ 2. With the aid of gravitational lensing and Keck laser-assisted adaptive optics, the spatial resolution of these sub-luminous galaxies is at a few hundred parsecs. First, we demonstrate that high spatial resolution is crucial in diagnosing the kinematic properties and dynamical maturity of z ∼ 2 galaxies. We observe a significantly lower fraction of rotationally-supported systems than what has been claimed in lower spatial resolution surveys. Second, we find a much larger fraction of z ∼ 2 galaxies with weak metallicity gradients, contrary to the simple picture suggested by earlier studies that well-ordered rotation develops concurrently with established steep metal gradients in all but merging systems. Comparing our observations with the predictions of hydronamical simulations, strong feedback is likely to play a key role in flattening metal gradients in early star-forming galaxies.

  19. The vertical metallicity gradient of the Milky Way disk: transitions in [α/Fe] populations

    International Nuclear Information System (INIS)

    Schlesinger, Katharine J.; Johnson, Jennifer A.; Rockosi, Constance M.; Lee, Young Sun; Beers, Timothy C.; Harding, Paul; Allende Prieto, Carlos; Bird, Jonathan C.; Schönrich, Ralph; Yanny, Brian; Schneider, Donald P.; Weaver, Benjamin A.; Brinkmann, Jon

    2014-01-01

    Using G dwarfs from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) survey, we have determined the vertical metallicity gradient in the Milky Way's disk and examined how this gradient varies for different [α/Fe] subsamples. Our sample contains over 40,000 stars with low-resolution spectroscopy over 144 lines of sight. It also covers a significant disk volume, between ∼0.3 and 1.6 kpc from the Galactic plane, and allows us to examine the disk in situ, whereas previous analyses were more limited in scope. Furthermore, this work does not presuppose a disk structure, whether composed of a single complex population or distinct thin and thick disk components. We employ the SEGUE Stellar Parameter Pipeline to obtain estimates of stellar parameters, [Fe/H], and [α/Fe] and extract multiple volume-complete subsamples of approximately 1000 stars each. Based on SEGUE's target-selection algorithm, we adjust each subsample to determine an unbiased picture of disk chemistry; consequently, each individual star represents the properties of many. The metallicity gradient is –0.243 −0.053 +0.039 dex kpc –1 for the entire sample, which we compare to various literature results. This gradient stems from the different [α/Fe] populations inhabiting different ranges of height above the Galactic plane. Each [α/Fe] subsample shows little change in median [Fe/H] with height. If we associate [α/Fe] with age, the negligible gradients of our [α/Fe] subsamples suggest that stars formed in different epochs exhibit comparable vertical structure, implying similar star formation processes and evolution.

  20. Electronic structure and electric fields gradients of crystalline Sn(II) and Sn(IV) compounds

    International Nuclear Information System (INIS)

    Terra, J.; Guenzburger, D.

    1991-01-01

    The electronic structures of clusters representing crystalline compounds of Sn(II) and Sn(IV) were investigated, employing the first-principles Discrete Variational method and Local Density theory. Densities of states and related parameters were obtained and compared with experimental measurements and with results from band structure calculations. Effects of cluster size and of cluster truncated bonds are discussed. Electric field gradients at the Sn nucleus were calculated; results are analysed in terms of charge distribution and chemical bonding in the crystals. (author)

  1. Finite element implementation and numerical issues of strain gradient plasticity with application to metal matrix composites

    DEFF Research Database (Denmark)

    Frederiksson, Per; Gudmundson, Peter; Mikkelsen, Lars Pilgaard

    2009-01-01

    A framework of finite element equations for strain gradient plasticity is presented. The theoretical framework requires plastic strain degrees of freedom in addition to displacements and a plane strain version is implemented into a commercial finite element code. A couple of different elements...... of quadrilateral type are examined and a few numerical issues are addressed related to these elements as well as to strain gradient plasticity theories in general. Numerical results are presented for an idealized cell model of a metal matrix composite under shear loading. It is shown that strengthening due...... to fiber size is captured but strengthening due to fiber shape is not. A few modelling aspects of this problem are discussed as well. An analytic solution is also presented which illustrates similarities to other theories....

  2. Richness, coverage and concentration of heavy metals in vascular epiphytes along an urbanization gradient.

    Science.gov (United States)

    Becker, Diego Fedrizzi Petry; Linden, Rafael; Schmitt, Jairo Lizandro

    2017-04-15

    Richness, coverage and concentration of heavy metals in vascular epiphytes were analyzed in isolated trees along an urbanization gradient in Southern Brazil. A total of 20 phorophytes were sampled in the main street of each site. Concentrations of chromium, cadmium, lead, manganese, nickel and zinc were measured in the leaves of Tillandsia recurvata L. using Graphite Furnace Atomic Absorption Spectrophotometry. A decreasing gradient of epiphyte richness and coverage was observed as urbanization increased. Vehicle fleet and demographic density were the parameters most correlated with the reduction of epiphytic diversity. In T. recurvata, significantly higher values of cadmium, lead and zinc were recorded in the most urbanized areas, and were strongly related to the vehicle fleet and to the demographic density in these sites. The results demonstrated that these parameters could be applied to the diagnosis of environmental quality in urban areas, allowing standardized analyses in other regions. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Spectrophotometry of four H II regions in the Perseus arm and a reassessment of galactic abundance gradients

    International Nuclear Information System (INIS)

    Talent, D.L.; Dufour, R.J.

    1979-01-01

    The results from deep spectrophotometry of four Perseus arm H II regions (NGC 1624, NGC 2359, NGC 7538, and NGC 7635) obtained with the KPNO IIDS are presented. The observed line strengths are used to derive electron temperatures, densities, and the relative concentrations of H, He, N, O, S, Cl, and Ar in the nebulae. These abundances are combined with similarly derived abundances for seven other well-observed galactic H II regions, and are used to estimate the magnitude of galactic abundance gradients over the 8--14 kpc region of the solar neighborhood.Significant radial gradients for oxygen and nitrogen are found: d log (O/H)/dR=-0.059 +- 0.017 kpc -1 and d log (N/H)/dR= -0.083 +- 0.018 kpc -1 , while only marginal evidence for a helium gradient is found: d log (He/H)/dR=-0.008 +- 0.008 kpc -1 . Little evidence for gradient in S/H is found. From the red [N II] and [S II] lines we found d log (N + /S + )/dR=-0.068 +- 0.024 kpc -1 , which suggests that a radial gradient in S/O exists in the Galaxy. The O/H gradient found in this study is similar to that found from planetary nebulae, while the N/H gradient is significantly smaller. These results suggest that most of the nitrogen in the interstellar medium of the Galaxy was produced by primary nucleosynthesis processes.We also find evidence that the radial O/H and N/H gradients for H II regions in a given spiral arm are 2 to 3 times steeper than the global gradients over the 8--14 kpc interval in galactocentric distance. For four H II regions in the Sagittarius arm we found d log (O/H)/dR=-0.24 kpc -1 and d log (N/H)/dR=-0.16 kpc -1 . For five H II regions in the Perseus arm we found d log (O/H)/dR=-0.18 kpc -1 and d log (N/H)/dR=-0.15 kpc -1 . The larger magnitudes of these gradients are greater than those of the global gradients by amounts which exceed reasonable errors in abundances and/or relative distances

  4. Metals pollution tracing in the sewerage network using the diffusive gradients in thin films technique.

    Science.gov (United States)

    Thomas, P

    2009-01-01

    Diffusive Gradients in Thin-films (DGT) is a quantitative, passive monitoring technique that can be used to measure concentrations of trace species in situ in solutions. Its potential for tracing metals pollution in the sewer system has been investigated by placing the DGT devices into sewage pumping stations and into manholes, to measure the concentration of certain metals in the catchment of a sewage treatment works with a known metals problem. In addition the methodology and procedure of using the DGT technique in sewers was investigated. Parameters such as temperature and pH were measured to ensure they were within the limits required by the DGT devices, and the optimum deployment time was examined. It was found that although the results given by the DGT technique could not be considered to be fully quantitative, they could be used to identify locations that were showing an excess concentration of metals, and hence trace pollution back to its source. The DGT technique is 'user friendly' and requires no complicated equipment for deployment or collection, and minimal training for use. It is thought that this is the first time that the DGT technique has been used in situ in sewers for metals pollution tracing.

  5. MASSIV: Mass Assembly Survey with SINFONI in VVDS. III. Evidence for positive metallicity gradients in z ~ 1.2 star-forming galaxies

    Science.gov (United States)

    Queyrel, J.; Contini, T.; Kissler-Patig, M.; Epinat, B.; Amram, P.; Garilli, B.; Le Fèvre, O.; Moultaka, J.; Paioro, L.; Tasca, L.; Tresse, L.; Vergani, D.; López-Sanjuan, C.; Perez-Montero, E.

    2012-03-01

    Aims: The estimate of radial abundance gradients in high-redshift galaxies allows to constrain their star formation history and their interplay with the surrounding intergalactic medium. Methods: We present VLT/SINFONI integral-field spectroscopy of a first sample of 50 galaxies at z ~ 1.2 in the MASSIV survey. Using the N2 ratio between the [N ii]6584 and Hα rest-frame optical emission lines as a proxy for oxygen abundance in the interstellar medium, we measured the metallicity of the sample galaxies. We developed a tool to extract spectra in annular regions, leading to a spatially resolved estimate of the oxygen abundance in each galaxy. We were able to derive a metallicity gradient for 26 galaxies in our sample and discovered a significant fraction of galaxies with a "positive" gradient. Using a simple chemical evolution model, we derived infall rates of pristine gas onto the disks. Results: Seven galaxies display a positive gradient at a high confidence level. Four out of these are interacting, and one is a chain galaxy. We suggest that interactions might be responsible for shallowing and even inverting the abundance gradient. We also identify two interesting correlations in our sample: a) galaxies with higher gas velocity dispersion have shallower/positive gradients; and b) metal-poor galaxies tend to show a positive gradient, whereas metal-rich ones tend to show a negative one. This last observation can be explained by the infall of metal-poor gas into the center of the disks. We address the question of the origin of this infall under the influence of gas flows triggered by interactions and/or cold gas accretion. All the data published in this paper are publicly available at the time of publication following this link: http://cosmosdb.lambrate.inaf.it/VVDS-SINFONI. This work is based on observations collected at the European Southern Observatory (ESO) Very Large Telescope, Paranal, Chile, as part of the Programs 179.A-0823, 78.A-0177, and 75.A-0318. This

  6. Calculation of forces acting on an impurity in a metal subjected to a temperature gradient

    International Nuclear Information System (INIS)

    Gerl, M.

    1966-01-01

    In a metal subject to a temperature gradient, an impurity is submitted to both an electrostatic force due to the thermoelectric field and a force due to the scattering of electrons and phonons by this point defect. The scattering of the electrons is treated using a semi-classical approach and a quantum mechanical method. The numerical computation for several impurities in Cu, Ag, and Au requires the knowledge of the resistivity cross-section. and of the thermoelectric power of the impurity in the metal. A tentative estimation of the force due to the phonon-scattering is given for the self-diffusion in Cu. However, the approximations of this calculation do not allow a good comparison with the force due to the electrons. (author) [fr

  7. Cold Test Results of the ISAC-II Medium Beta High Gradient Cryomodule

    CERN Document Server

    Laxdal, R E; Clark, G S; Fong, K; Mitra, A K; Poirier, R L; Rawnsley, B; Ries, T; Sekatchev, I; Stanford, G; Zvyagintsev, V

    2004-01-01

    Many proposals (RIA, Eurisol, ISAC-II) are emerging for a new generation of high gradient heavy ion accelerators. The ISAC-II medium beta cryomodule represents the first realized application that encorporates many new techniques to improve the performance over machines presently being used for beam delivery. The machine lattice, compatible with multi-charge acceleration, uses high field (9T) superconducting solenoids with bucking coils for active fringe field compensation. The bulk niobium quarter wave medium beta cavity produces 6 MV/m over an effective length of 18cm with a peak surface field of ~30 MV/m. TRIUMF has developed a mechanical tuner capable of both coarse (kHz) and fine (Hz) frequency adjustments of the cavity. The demonstrated tuner resolution is better than 0.1 μm (0.6 Hz). A new rf coupling loop has been developed that operates at 200 Watts forward power with less than 0.5 Watt of power being added to the helium load. Cold alignment in ISAC-II has been done with rf pick-ups using a ...

  8. (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, ...

  9. Subcellular metal partitioning in larvae of the insect Chaoborus collected along an environmental metal exposure gradient (Cd, Cu, Ni and Zn)

    Energy Technology Data Exchange (ETDEWEB)

    Rosabal, Maikel; Hare, Landis [Institut national de la Recherche scientifique, Centre Eau Terre Environnement (INRS-ETE), 490 de la Couronne, Quebec, Quebec, G1K 9A9 (Canada); Campbell, Peter G.C., E-mail: peter.campbell@ete.inrs.ca [Institut national de la Recherche scientifique, Centre Eau Terre Environnement (INRS-ETE), 490 de la Couronne, Quebec, Quebec, G1K 9A9 (Canada)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Midge larvae were collected from 12 lakes representing Cd, Cu, Ni and Zn gradients. Black-Right-Pointing-Pointer Along the gradients, the heat-stable protein fractions increased for Cd, Ni and Cu. Black-Right-Pointing-Pointer However, this metal detoxification response was incomplete for Cd and Ni. Black-Right-Pointing-Pointer Concentrations of these two metals increased in putative metal-sensitive fractions. Black-Right-Pointing-Pointer Metal detoxification is Chaoborus is compared to that in other freshwater animals. - Abstract: Larvae of the phantom midge Chaoborus are common and widespread in lakes contaminated by metals derived from mining and smelting activities. To explore how this insect is able to cope with potentially toxic metals, we determined total metal concentrations and subcellular metal partitioning in final-instar Chaoborus punctipennis larvae collected from 12 lakes situated along gradients in aqueous Cd, Cu, Ni and Zn concentrations. Concentrations of the non-essential metals Cd and Ni were more responsive to aqueous metal gradients than were larval concentrations of the essential metals Cu and Zn; these latter metals were better regulated and exhibited only 2-3-fold increases between the least and the most contaminated lakes. Metal partitioning was determined by homogenization of larvae followed by differential centrifugation, NaOH digestion and heat denaturation steps so as to separate the metals into operationally defined metal-sensitive fractions (heat-denaturable proteins (HDP), mitochondria, and lysosomes/microsomes) and metal-detoxified fractions (heat stable proteins (HSP) and NaOH-resistant or granule-like fractions). Of these five fractions, the HSP fraction was the dominant metal-binding compartment for Cd, Ni and Cu. The proportions and concentrations of these three metals in this fraction increased along the metal bioaccumulation gradient, which suggests that metallothionein-like proteins

  10. Multi-metals column adsorption of lead(II), cadmium(II) and manganese(II) onto natural bentonite clay.

    Science.gov (United States)

    Alexander, Jock Asanja; Surajudeen, Abdulsalam; Aliyu, El-Nafaty Usman; Omeiza, Aroke Umar; Zaini, Muhammad Abbas Ahmad

    2017-10-01

    The present work was aimed at evaluating the multi-metals column adsorption of lead(II), cadmium(II) and manganese(II) ions onto natural bentonite. The bentonite clay adsorbent was characterized for physical and chemical properties using X-ray diffraction, X-ray fluorescence, Brunauer-Emmett-Teller surface area and cation exchange capacity. The column performance was evaluated using adsorbent bed height of 5.0 cm, with varying influent concentrations (10 mg/L and 50 mg/L) and flow rates (1.4 mL/min and 2.4 mL/min). The result shows that the breakthrough time for all metal ions ranged from 50 to 480 minutes. The maximum adsorption capacity was obtained at initial concentration of 10 mg/L and flow rate of 1.4 mL/min, with 2.22 mg/g of lead(II), 1.71 mg/g of cadmium(II) and 0.37 mg/g of manganese(II). The order of metal ions removal by natural bentonite is lead(II) > cadmium(II) > manganese(II). The sorption performance and the dynamic behaviour of the column were predicted using Adams-Bohart, Thomas, and Yoon-Nelson models. The linear regression analysis demonstrated that the Thomas and Yoon-Nelson models fitted well with the column adsorption data for all metal ions. The natural bentonite was effective for the treatment of wastewater laden with multi-metals, and the process parameters obtained from this work can be used at the industrial scale.

  11. Total vs. internal element concentrations in Scots pine needles along a sulphur and metal pollution gradient

    International Nuclear Information System (INIS)

    Rautio, Pasi; Huttunen, Satu

    2003-01-01

    Different methods should be used for foliar analyses of trees used as bioindicators of pollution, than those analyses used in nutritional studies of trees. - Analysis of foliar elements is a commonly used method for studying tree nutrition and for monitoring the impacts of air pollutants on forest ecosystems. Interpretations based on the results of foliar element analysis may, however, be different in nutrition vs. monitoring studies. We studied the impacts of severe sulphur and metal (mainly Cu and Ni) pollution on the element concentrations (Al, Ca, Cu, Fe, K, Mg, Mn, Ni, P, Pb, S and Zn) in Scots pine (Pinus sylvestris L.) foliage along an airborne sulphur and metal pollution gradient. Emphasis was put on determining the contribution of air-borne particles that have accumulated on needle surfaces to the total foliage concentrations. A comparison of two soil extraction methods was carried out in order to obtain a reliable estimate of plant-available element concentrations in the soil. Element concentrations in the soil showed only a weak relationship with internal foliar concentrations. There were no clear differences between the total and internal needle S concentrations along the gradient, whereas at the plot closest to the metal smelter complex the total Cu concentrations in the youngest needles were 1.3-fold and Ni concentrations over 1.6-fold higher than the internal needle concentrations. Chloroform-extracted surface wax was found to have Ni and Cu concentrations of as high as 3000 and 600 μg/g of wax, respectively. Our results suggest that bioindicator studies (e.g. monitoring studies) may require different foliar analysis techniques from those used in studies on the nutritional status of trees

  12. Removal of Pb(II), Cu(II) and Cd(II) from aqueous solution by some fungi and natural adsorbents in single and multiple metal systems

    International Nuclear Information System (INIS)

    Shoaib, A.; Badar, T.; Aslam, N.

    2011-01-01

    Six fungal and 10 natural biosorbents were analyzed for their Cu(II), Cd(II) and Pb(II) uptake capacity from single, binary and ternary metal ion system. Preliminary screening biosorption of assays revealed 2 fungi (Aspergillus niger and Cunninghamella echinulata) and three natural [Cicer arietinum husk, Moringa oleifera flower and soil (clay)] adsorbents hold considerable high adsorption efficiency and capacity for 3 meta l ions amongst the adsorbents. Further biosorption trials with five elected adsorbents showed a considerable reduction in metal uptake capability of adsorbents in binary- and ternary systems as compared to singly metal system. Cd(II) manifested the highest inhibitory effect on the biosorption of other metal ions, followed by Pb(II) and Cu(II). On account of metal preference, the selectivity order for metal ion towards the studied biomass matrices was Pb(II) (40-90%) > Cd(II) (2-53%) > Cu(II) (2-30%). (author)

  13. Adsorption of Pb(II), Cu(II), Cd(II), Zn(II), Ni(II), Fe(II), and As(V) on bacterially produced metal sulfides.

    Science.gov (United States)

    Jong, Tony; Parry, David L

    2004-07-01

    The adsorption of Pb(II), Cu(II), Cd(II), Zn(II), Ni(II), Fe(II) and As(V) onto bacterially produced metal sulfide (BPMS) material was investigated using a batch equilibrium method. It was found that the sulfide material had adsorptive properties comparable with those of other adsorbents with respect to the specific uptake of a range of metals and, the levels to which dissolved metal concentrations in solution can be reduced. The percentage of adsorption increased with increasing pH and adsorbent dose, but decreased with increasing initial dissolved metal concentration. The pH of the solution was the most important parameter controlling adsorption of Cd(II), Cu(II), Fe(II), Ni(II), Pb(II), Zn(II), and As(V) by BPMS. The adsorption data were successfully modeled using the Langmuir adsorption isotherm. Desorption experiments showed that the reversibility of adsorption was low, suggesting high-affinity adsorption governed by chemisorption. The mechanism of adsorption for the divalent metals was thought to be the formation of strong, inner-sphere complexes involving surface hydroxyl groups. However, the mechanism for the adsorption of As(V) by BPMS appears to be distinct from that of surface hydroxyl exchange. These results have important implications to the management of metal sulfide sludge produced by bacterial sulfate reduction.

  14. Gradients of electric fields and effective charges in alkali metal permanganates on NMR data

    International Nuclear Information System (INIS)

    Tarasov, V.P.; Kirakosyan, G.A.; Meladze, M.A.; German, K.Eh.

    1993-01-01

    Pulse method of 55 Mn, 39 K, 87 Rb, 133 Cs NMR in 7.04 T field was used to study polycrystal permanganates of alkali metals KMnO 4 , RbMnO 4 , CsMnO 4 in 100-440 K range. Qaudrupole bond constants, parameters of tensor asymmetry of electric field gradient (EFG) and isotropic values of chemical shifts were determined in result of analysis of resonance line shape. Cation positions in RbMnO 4 and CsMnO 4 are characterized by two nonequivalent states with 1:1 occupation. Effective charges on oxygen and manganese atoms were calculated in the framework of point charge model, using structural data and experimental EFG values on cation nuclei

  15. Gradient plasticity for thermo-mechanical processes in metals with length and time scales

    Science.gov (United States)

    Voyiadjis, George Z.; Faghihi, Danial

    2013-03-01

    A thermodynamically consistent framework is developed in order to characterize the mechanical and thermal behavior of metals in small volume and on the fast transient time. In this regard, an enhanced gradient plasticity theory is coupled with the application of a micromorphic approach to the temperature variable. A physically based yield function based on the concept of thermal activation energy and the dislocation interaction mechanisms including nonlinear hardening is taken into consideration in the derivation. The effect of the material microstructural interface between two materials is also incorporated in the formulation with both temperature and rate effects. In order to accurately address the strengthening and hardening mechanisms, the theory is developed based on the decomposition of the mechanical state variables into energetic and dissipative counterparts which endowed the constitutive equations to have both energetic and dissipative gradient length scales for the bulk material and the interface. Moreover, the microstructural interaction effect in the fast transient process is addressed by incorporating two time scales into the microscopic heat equation. The numerical example of thin film on elastic substrate or a single phase bicrystal under uniform tension is addressed here. The effects of individual counterparts of the framework on the thermal and mechanical responses are investigated. The model is also compared with experimental results.

  16. SDSS-IV MaNGA: environmental dependence of stellar age and metallicity gradients in nearby galaxies

    Science.gov (United States)

    Zheng, Zheng; Wang, Huiyuan; Ge, Junqiang; Mao, Shude; Li, Cheng; Li, Ran; Mo, Houjun; Goddard, Daniel; Bundy, Kevin; Li, Hongyu; Nair, Preethi; Lin, Lihwai; Long, R. J.; Riffel, Rogério; Thomas, Daniel; Masters, Karen; Bizyaev, Dmitry; Brownstein, Joel R.; Zhang, Kai; Law, David R.; Drory, Niv; Roman Lopes, Alexandre; Malanushenko, Olena

    2017-03-01

    We present a study on the stellar age and metallicity distributions for 1105 galaxies using the STARLIGHT software on MaNGA (Mapping Nearby Galaxies at APO) integral field spectra. We derive age and metallicity gradients by fitting straight lines to the radial profiles, and explore their correlations with total stellar mass M*, NUV - r colour and environments, as identified by both the large-scale structure (LSS) type and the local density. We find that the mean age and metallicity gradients are close to zero but slightly negative, which is consistent with the inside-out formation scenario. Within our sample, we find that both the age and metallicity gradients show weak or no correlation with either the LSS type or local density environment. In addition, we also study the environmental dependence of age and metallicity values at the effective radii. The age and metallicity values are highly correlated with M* and NUV - r and are also dependent on LSS type as well as local density. Low-mass galaxies tend to be younger and have lower metallicity in low-density environments while high-mass galaxies are less affected by environment.

  17. Some calculated contributions to the electric field gradient in nontransition metals

    International Nuclear Information System (INIS)

    Lodge, K.W.

    1978-01-01

    The electric field gradient (EFG) at a nucleus in the metals Be, Mg, Zn, Cd, In and Ga (both alpha and beta forms) has been calculated. Model potential theory has been used to represent the conduction electron distribution external to the ion core at whose nucleus the EFG is calculated. For the metals Be and Mg the local conduction electron effects have been obtained by orthogonalising the model wavefunctions to the occupied core states. The effect of the nuclear electric quadrupole moment (EQM) perturbing the conduction electrons has also been considered and the effect of self-consistently obtaining conduction electron and distorted core electron states has been discussed. The conduction electrons external to the core are found to produce an EFG which partly screens the ionic contribution. A large contribution is obtained from the orthogonalisation terms, substantially improving the agreement with experiment for Mg. The effect of including the nuclear EQM perturbation of the conduction electrons is found to be of the order of 10% of the calculated total EFG for Be and Mg. (author)

  18. Macrocyclic receptor showing extremely high Sr(II)/Ca(II) and Pb(II)/Ca(II) selectivities with potential application in chelation treatment of metal intoxication.

    Science.gov (United States)

    Ferreirós-Martínez, Raquel; Esteban-Gómez, David; Tóth, Éva; de Blas, Andrés; Platas-Iglesias, Carlos; Rodríguez-Blas, Teresa

    2011-04-18

    Herein we report a detailed investigation of the complexation properties of the macrocyclic decadentate receptor N,N'-Bis[(6-carboxy-2-pyridil)methyl]-4,13-diaza-18-crown-6 (H(2)bp18c6) toward different divalent metal ions [Zn(II), Cd(II), Pb(II), Sr(II), and Ca(II)] in aqueous solution. We have found that this ligand is especially suited for the complexation of large metal ions such as Sr(II) and Pb(II), which results in very high Pb(II)/Ca(II) and Pb(II)/Zn(II) selectivities (in fact, higher than those found for ligands widely used for the treatment of lead poisoning such as ethylenediaminetetraacetic acid (edta)), as well as in the highest Sr(II)/Ca(II) selectivity reported so far. These results have been rationalized on the basis of the structure of the complexes. X-ray crystal diffraction, (1)H and (13)C NMR spectroscopy, as well as theoretical calculations at the density functional theory (B3LYP) level have been performed. Our results indicate that for large metal ions such as Pb(II) and Sr(II) the most stable conformation is Δ(δλδ)(δλδ), while for Ca(II) our calculations predict the Δ(λδλ)(λδλ) form being the most stable one. The selectivity that bp18c6(2-) shows for Sr(II) over Ca(II) can be attributed to a better fit between the large Sr(II) ions and the relatively large crown fragment of the ligand. The X-ray crystal structure of the Pb(II) complex shows that the Δ(δλδ)(δλδ) conformation observed in solution is also maintained in the solid state. The Pb(II) ion is endocyclically coordinated, being directly bound to the 10 donor atoms of the ligand. The bond distances to the donor atoms of the pendant arms (2.55-2.60 Å) are substantially shorter than those between the metal ion and the donor atoms of the crown moiety (2.92-3.04 Å). This is a typical situation observed for the so-called hemidirected compounds, in which the Pb(II) lone pair is stereochemically active. The X-ray structures of the Zn(II) and Cd(II) complexes show that

  19. Characterizing the production and retention of dissolved iron as Fe(II) across a natural gradient in chlorophyll concentrations in the Southern Drake Passage - Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Katherine Barbeau

    2007-04-10

    . As a co-PI in the NSF/OPP-funded project, I was responsible for iron addition incubation and radiotracer experiments, and analysis of iron chemistry, including iron-organic speciation. This final technical report describes the results of my DOE funded project to analyse reduced iron species using an FeLume flow injection analysis chemiluminescence system as an extension of my work on the NSF/OPP project. On the cruise in 2004, spatial and temporal gradients in Fe(II) were determined, and on-board incubations were conducted to study Fe(II) lifetime and production. Following the cruise a further series of experiments was conducted in my laboratory to study Fe(II) lifetimes and photoproduction under conditions typical of high latitude waters. The findings of this study suggest that, in contrast to results observed during mesoscale iron addition experiments, steady-state levels of Fe(II) are likely to remain low (below detection) even within a significant gradient in dissolved Fe concentrations produced as a result of natural iron enrichment processes. Fe(II) is likely to be produced, however, as a reactive intermediate associated with photochemical reactions in surface waters. While Fe(II) lifetimes measured in the field in this study were commensurate with those determined in previously published Southern Ocean work, Fe(II) lifetimes reflective of realistic Southern Ocean environmental conditions have proven difficult to determine in a laboratory setting, due to contamination by trace levels of H2O2. Laboratory experiments demonstrated that direct ligand-to-metal charge transfer reactions of strong Fe(III)-organic complexes do appear to be a viable source of available Fe(II) in Antarctic waters, and further studies are needed to characterize the temperature dependence of this phenomenon.

  20. Quantitative analysis of O-2 and Fe2+ profiles in gradient tubes for cultivation of microaerophilic Iron(II)-oxidizing bacteria

    DEFF Research Database (Denmark)

    Lueder, U.; Druschel, G.; Emerson, D.

    2018-01-01

    The classical approach for the cultivation of neutrophilic microaerophilic Fe(II)-oxidizing bacteria is agar-based gradient tubes where these bacteria find optimal growth conditions in opposing gradients of oxygen (O-2) and dissolved Fe(II) (Fe2+). The goals of this study were to quantify...... imply that transfer of cultures to fresh tubes within 48-72 h is crucial to provide optimal growth conditions for microaerophilic Fe(II)-oxidizers, particularly for the isolation of new strains....

  1. Forewing structure of the solitary bee Osmia bicornis developing on heavy metal pollution gradient.

    Science.gov (United States)

    Szentgyörgyi, Hajnalka; Moroń, Dawid; Nawrocka, Anna; Tofilski, Adam; Woyciechowski, Michał

    2017-10-01

    Wild bees in natural conditions can develop under various environmental stressors. Heavy metal pollution of the environment is one of the most widely studied stressors in insects, yet its effect is poorly described in bees. We have measured how pollution of the environment along a zinc, cadmium and lead contamination gradient in Poland affects bee development, using red mason bees (Osmia bicornis) as a model and their forewing asymmetry measures to assess possible developmental instabilities. We have also described wing asymmetry measures in the red mason bee-an important managed pollinator species-for the first time. The development of bee larvae in a contaminated environment did not affect forewing asymmetry measures, but it did lead to a negative correlation of wing size with contamination in females. Bees also showed a clear change in their asymmetry measures between various seasons, suggesting other, unknown environmental factors affecting wing asymmetry more than pollution. Sexes were found to have different forewing shape and size, larger females having larger forewings than the smaller males. The direction of size asymmetry was in favour of the left side in both sexes and also shape differences between the left and right wings showed similar tendencies in males and females. The levels of forewing shape and size asymmetry were smaller in females, making them the more symmetrical sex.

  2. Anti-inflammatory drugs interacting with Zn(II), Cd(II) and Pt(II) metal ions.

    Science.gov (United States)

    Dendrinou-Samara, C; Tsotsou, G; Ekateriniadou, L V; Kortsaris, A H; Raptopoulou, C P; Terzis, A; Kyriakidis, D A; Kessissoglou, D P

    1998-09-01

    Complexes of Zn(II), Cd(II) and Pt(II) metal ions with the anti-inflammatory drugs, 1-methyl-5-(p-toluoyl)-1H-pyrrole-2-acetic acid (Tolmetin), alpha-methyl-4-(2-methylpropyl)benzeneacetic acid (Ibuprofen), 6-methoxy-alpha-methylnaphthalene-2-acetic acid (Naproxen) and 1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetic acid (indomethacin) have been synthesized and characterized. In the structurally characterized Cd(naproxen)2 complex the anti-inflammatory drugs acts as bidentate chelate ligand coordinatively bound to metal ions through the deprotonated carboxylate group. Crystal data for 1: [C32H26O8Cd], orthorhombic, space group P22(1)2(1), a = 5.693(2) (A), b = 8.760(3) (A), c = 30.74(1) (A), V = 1533(1) A3, Z = 2. Antibacterial and growth inhibitory activity is higher than that of the parent ligands or the platinum(II) diamine compounds.

  3. Ultrasonic measurement of through-thickness stress gradients in textured sheet metals

    International Nuclear Information System (INIS)

    Man Chising; Li Jianbo; Fan Xingyan; Lu Weiyang

    2000-01-01

    The objective of this investigation is to explore the possibility of using the dispersion of high-frequency Rayleigh waves for the evaluation of through-thickness stress gradients at the surface of metal sheets. We consider an orthorhombic sheet of cubic metal with through-thickness inhomogeneities in stress and texture, and adopt a coordinate system under which the rolling (RD), transverse (TD), and normal direction (ND) of the sheet are taken as the 1-, 2-, and 3-direction, respectively. We restrict our attention to the special case where only the stress components T 11 (x 3 ) and T 22 (x 3 ) in the sheet are nonzero, and consider only Rayleigh waves of sufficiently high frequency for which the sheet can be taken as the half-space x 3 ≥0. For Rayleigh waves of two different frequencies (with wave numbers k 1 and k k 2 respectively) propagating on the same wave path along either RD or TD, we appeal to an analysis of J. Li and Man to obtain a high-frequency asymptotic formula which gives the relative change in time-of-flight Δt/t 0 as (1/k 1 -1/k 2 ) times a linear combination of the derivatives T 11 ' (0), T 22 ' (0), W 4m0 ' (0)(m=0,2,4) and W 6m0 (0)(m=0,2,4,6) at the surface are ascertained and the material constants in the acoustoelastic consitutive equation of this polycrystal are known. An experiment was performed on an AA7075-T651 aluminum alloy beam, in which Δt/t 0 was measured for various values of T 11 (0) and T 11 ' (0) produced by beam bending (with (T 22 ≡0). The relevant texture coefficients of the beam were measured by X-ray diffraction. To obtain specific predictions from the aforementioned symptotic formula, we replace the material constants of the sample by their counterparts predicted for polycrystalline (pure) aluminum by the Man-Paroni model. The predictions and Δt/t 0 are then compared with the experimental results

  4. Theoretical study of heavy metal Cd, Cu, Hg, and Ni(II) adsorption on the kaolinite(0 0 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jian, E-mail: zhaojian0209@aliyun.com [Institute of Applied Physics and Computational Mathematics, PO Box 8009, Beijing 100088 (China); State Key Laboratory of Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China); He, Man-Chao [State Key Laboratory of Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China)

    2014-10-30

    Highlights: • We investigated the adsorption of Cd, Cu, Hg, and Ni(II) on kaolinite(0 0 1) surface. • The adsorption capabilities of the kaolinite for HM atoms were Ni > Cu > Cd > Hg(II). • The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms. • The adsorption energy decreases with the coverage for Ni(II) atoms. - Abstract: Heavy metal pollution is currently of great concern because it has been recognized as a potential threat to air, water, and soil. Adsorption was one of the most popular methods for the removal of heavy metal. The adsorption of heavy metal Cd, Cu, Hg, and Ni(II) atoms on the hydroxylated (0 0 1) surface of kaolinite was investigated using density-functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics were systematically studied for a wide range of coverage Θ [from 0.11 to 1.0 monolayers (ML)] and adsorption sites. The most stable among all possible adsorption sites for Cd(II) atom was the two-fold bridge site followed by the one-fold top site, and the top site was the most favorite adsorption site for Cu and Ni(II) atoms, while the three-fold hollow site was the most stable adsorption site for Hg(II) atom followed by the two-fold bridge site. The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms, thus indicating the higher stability of surface adsorption and a tendency to the formation of adsorbate islands (clusters) with increasing the coverage. However, the adsorption energy of Ni(II) atoms decreases when increasing the coverage. The adsorption capabilities of the kaolinite clay for the heavy metal atoms were in the order of Ni > Cu > Cd > Hg(II). The other properties of the Cd, Cu, Hg, and Ni(II)/kaolinite(0 0 1) system including the different charge distribution, the lattice relaxation, and the electronic density of states were also studied and discussed in detail.

  5. Theoretical study of heavy metal Cd, Cu, Hg, and Ni(II) adsorption on the kaolinite(0 0 1) surface

    International Nuclear Information System (INIS)

    Zhao, Jian; He, Man-Chao

    2014-01-01

    Highlights: • We investigated the adsorption of Cd, Cu, Hg, and Ni(II) on kaolinite(0 0 1) surface. • The adsorption capabilities of the kaolinite for HM atoms were Ni > Cu > Cd > Hg(II). • The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms. • The adsorption energy decreases with the coverage for Ni(II) atoms. - Abstract: Heavy metal pollution is currently of great concern because it has been recognized as a potential threat to air, water, and soil. Adsorption was one of the most popular methods for the removal of heavy metal. The adsorption of heavy metal Cd, Cu, Hg, and Ni(II) atoms on the hydroxylated (0 0 1) surface of kaolinite was investigated using density-functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics were systematically studied for a wide range of coverage Θ [from 0.11 to 1.0 monolayers (ML)] and adsorption sites. The most stable among all possible adsorption sites for Cd(II) atom was the two-fold bridge site followed by the one-fold top site, and the top site was the most favorite adsorption site for Cu and Ni(II) atoms, while the three-fold hollow site was the most stable adsorption site for Hg(II) atom followed by the two-fold bridge site. The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms, thus indicating the higher stability of surface adsorption and a tendency to the formation of adsorbate islands (clusters) with increasing the coverage. However, the adsorption energy of Ni(II) atoms decreases when increasing the coverage. The adsorption capabilities of the kaolinite clay for the heavy metal atoms were in the order of Ni > Cu > Cd > Hg(II). The other properties of the Cd, Cu, Hg, and Ni(II)/kaolinite(0 0 1) system including the different charge distribution, the lattice relaxation, and the electronic density of states were also studied and discussed in detail

  6. On the metallicity gradients of the Galactic disk as revealed by LSS-GAC red clump stars

    Science.gov (United States)

    Huang, Yang; Liu, Xiao-Wei; Zhang, Hua-Wei; Yuan, Hai-Bo; Xiang, Mao-Sheng; Chen, Bing-Qiu; Ren, Juan-Juan; Sun, Ning-Chen; Wang, Chun; Zhang, Yong; Hou, Yong-Hui; Wang, Yue-Fei; Yang, Ming

    2015-08-01

    Using a sample of over 70 000 red clump (RC) stars with 5%-10% distance accuracy selected from the LAMOST Spectroscopic Survey of the Galactic Anti-center (LSS-GAC), we study the radial and vertical gradients of the Galactic disk(s) mainly in the anti-center direction, covering a significant volume of the disk in the range of projected Galactocentric radius 7 ≤ RGC ≤ 14 kpc and height from the Galactic midplane 0 ≤ |Z| ≤ 3 kpc. Our analysis shows that both the radial and vertical metallicity gradients are negative across much of the volume of the disk that is probed, and they exhibit significant spatial variations. Near the solar circle (7 ≤ RGC ≤ 115 kpc), the radial gradient has a moderately steep, negative slope of -0.08 dex kpc-1 near the midplane (|Z| plane, suggesting that the outer disk may have experienced an evolutionary path different from that of the inner disk. The vertical gradients are found to flatten largely with increasing RGC. However, the vertical gradient of the lower disk (0 ≤ |Z| ≤ 1 kpc) is found to flatten with RGC quicker than that of the upper disk (1 < |Z| ≤ 3 kpc). Our results should provide strong constraints on the theory of disk formation and evolution, as well as the underlying physical processes that shape the disk (e.g. gas flows, radial migration, and internal and external perturbations).

  7. Synthesis, spectral characterization thermal stability, antimicrobial studies and biodegradation of starch–thiourea based biodegradable polymeric ligand and its coordination complexes with [Mn(II), Co(II), Ni(II), Cu(II), and Zn(II)] metals

    OpenAIRE

    Nahid Nishat; Ashraf Malik

    2016-01-01

    A biodegradable polymer was synthesized by the modification reaction of polymeric starch with thiourea which is further modified by transition metals, Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). All the polymeric compounds were characterized by (FT-IR) spectroscopy, 1H NMR spectroscopy, 13C NMR spectroscopy, UV–visible spectra, magnetic moment measurements, thermogravimetric analysis (TGA) and antibacterial activities. Polymer complexes of Mn(II), Co(II) and Ni(II) show octahedral geometry, wh...

  8. Trends in detoxification enzymes and heavy metal accumulation in ground beetles (Coleoptera: Carabidae) inhabiting a gradient of pollution.

    Science.gov (United States)

    Stone, David; Jepson, Paul; Laskowski, Ryszard

    2002-05-01

    Non-specfic carboxylesterase and glutathione S-transferase activity was measured in the ground beetle, Pterosthicus oblongopunctatus (Coleoptera: Carabidae), from five sites along a gradient of heavy metal pollution. A previous study determined that beetles from the two most polluted sites (site codes OLK2 and OLK3) were more susceptible to additional stressors compared with beetles from the reference site (Stone et al., Environ. Pollut. 113, 239-244 2001), suggesting the possibility of physiological impairment. Metal body burdens in ground beetles from five sites along the gradient ranged from 79 to 201 microg/g Zn, 0.174 to 8.66 microg/g Pb and 1.14 to 10.8 microg/g Cd, whereas Cu seemed to be efficiently regulated regardless of metal levels in the soil. Beetle mid- and hindguts were homogenized and the soluble fraction containing glutathione S-transferase (GST) and carboxylesterase (CaE) was assayed using kinetic analyses. Significantly higher levels of GST were found only in female beetles from the most polluted sites (OLK2 and OLK3; P=0.049, Pground beetles in association with metal body burdens.

  9. Metallicity Variations in the Type II Globular Cluster NGC 6934

    Science.gov (United States)

    Marino, A. F.; Yong, D.; Milone, A. P.; Piotto, G.; Lundquist, M.; Bedin, L. R.; Chené, A.-N.; Da Costa, G.; Asplund, M.; Jerjen, H.

    2018-06-01

    The Hubble Space Telescope photometric survey of Galactic globular clusters (GCs) has revealed a peculiar “chromosome map” for NGC 6934. In addition to a typical sequence, similar to that observed in Type I GCs, NGC 6934 displays additional stars on the red side, analogous to the anomalous Type II GCs, as defined in our previous work. We present a chemical abundance analysis of four red giants in this GC. Two stars are located on the chromosome map sequence common to all GCs, and another two lie on the additional sequence. We find (i) star-to-star Fe variations, with the two anomalous stars being enriched by ∼0.2 dex. Because of our small-size sample, this difference is at the ∼2.5σ level. (ii) There is no evidence for variations in the slow neutron-capture abundances over Fe, at odds with what is often observed in anomalous Type II GCs, e.g., M 22 and ω Centauri (iii) no large variations in light elements C, O, and Na, compatible with locations of the targets on the lower part of the chromosome map where such variations are not expected. Since the analyzed stars are homogeneous in light elements, the only way to reproduce the photometric splits on the sub-giant (SGB) and the red giant (RGB) branches is to assume that red RGB/faint SGB stars are enhanced in [Fe/H] by ∼0.2. This fact corroborates the spectroscopic evidence of a metallicity variation in NGC 6934. The observed chemical pattern resembles only partially the other Type II GCs, suggesting that NGC 6934 might belong either to a third class of GCs, or be a link between normal Type I and anomalous Type II GCs. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile, and Gemini Telescope at Canada–France–Hawaii Telescope.

  10. Responses of microbial tolerance to heavy metals along a century-old metal ore pollution gradient in a subarctic birch forest.

    Science.gov (United States)

    Rousk, Johannes; Rousk, Kathrin

    2018-05-07

    Heavy metals are some of the most persistent and potent anthropogenic environmental contaminants. Although heavy metals may compromise microbial communities and soil fertility, it is challenging to causally link microbial responses to heavy metals due to various confounding factors, including correlated soil physicochemistry or nutrient availability. A solution is to investigate whether tolerance to the pollutant has been induced, called Pollution Induced Community Tolerance (PICT). In this study, we investigated soil microbial responses to a century-old gradient of metal ore pollution in an otherwise pristine subarctic birch forest generated by a railway source of iron ore transportation. To do this, we determined microbial biomass, growth, and respiration rates, and bacterial tolerance to Zn and Cu in replicated distance transects (1 m-4 km) perpendicular to the railway. Microbial biomass, growth and respiration rates were stable across the pollution gradient. The microbial community structure could be distinguished between sampled distances, but most of the variation was explained by soil pH differences, and it did not align with distance from the railroad pollution source. Bacterial tolerance to Zn and Cu started from background levels at 4 km distance from the pollution source, and remained at background levels for Cu throughout the gradient. Yet, bacterial tolerance to Zn increased 10-fold 100 m from the railway source. Our results show that the microbial community structure, size and performance remained unaffected by the metal ore exposure, suggesting no impact on ecosystem functioning. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Lagrangian torus fibration of quintic Calabi-Yau hypersurfaces II: Technical results on gradient flow construction

    OpenAIRE

    Ruan, Wei-Dong

    2004-01-01

    This paper is the sequel to my recent paper [10]. It will provide technical details of our gradient flow construction and related problems, which are essential for our construction of Lagrangian torus fibrations in [10] and subsequent papers [11, 13, 14].

  12. Effects of thermal aging on the microstructure of Type-II boundaries in dissimilar metal weld joints

    Science.gov (United States)

    Yoo, Seung Chang; Choi, Kyoung Joon; Bahn, Chi Bum; Kim, Si Hoon; Kim, Ju Young; Kim, Ji Hyun

    2015-04-01

    In order to investigate the effects of long-term thermal aging on the microstructural evolution of Type-II boundary regions in the weld metal of Alloy 152, a representative dissimilar metal weld was fabricated from Alloy 690, Alloy 152, and A533 Gr.B. This mock-up was thermally aged at 450 °C to accelerate the effects of thermal aging in a nuclear power plant operation condition (320 °C). The microstructure of the Type-II boundary region of the weld root, which is parallel to and within 100 μm of the fusion boundary and known to be more susceptible to material degradation, was then characterized after different aging times using a scanning electron microscope equipped with an energy dispersive X-ray spectroscope for micro-compositional analysis, electron backscattered diffraction detector for grain and grain boundary orientation analysis, and a nanoindenter for measurement of mechanical properties. Through this, it was found that a steep compositional gradient and high grain average misorientation is created in the narrow zone between the Type-II and fusion boundaries, while the concentration of chromium and number of low-angle grain boundaries increases with aging time. A high average hardness was also observed in the same region of the dissimilar metal welds, with hardness peaking with thermal aging simulating an operational time of 15 years.

  13. Multi-scale modification of metallic implants with pore gradients, polyelectrolytes and their indirect monitoring in vivo.

    Science.gov (United States)

    Vrana, Nihal E; Dupret-Bories, Agnes; Chaubaroux, Christophe; Rieger, Elisabeth; Debry, Christian; Vautier, Dominique; Metz-Boutigue, Marie-Helene; Lavalle, Philippe

    2013-07-01

    Metallic implants, especially titanium implants, are widely used in clinical applications. Tissue in-growth and integration to these implants in the tissues are important parameters for successful clinical outcomes. In order to improve tissue integration, porous metallic implants have being developed. Open porosity of metallic foams is very advantageous, since the pore areas can be functionalized without compromising the mechanical properties of the whole structure. Here we describe such modifications using porous titanium implants based on titanium microbeads. By using inherent physical properties such as hydrophobicity of titanium, it is possible to obtain hydrophobic pore gradients within microbead based metallic implants and at the same time to have a basement membrane mimic based on hydrophilic, natural polymers. 3D pore gradients are formed by synthetic polymers such as Poly-L-lactic acid (PLLA) by freeze-extraction method. 2D nanofibrillar surfaces are formed by using collagen/alginate followed by a crosslinking step with a natural crosslinker (genipin). This nanofibrillar film was built up by layer by layer (LbL) deposition method of the two oppositely charged molecules, collagen and alginate. Finally, an implant where different areas can accommodate different cell types, as this is necessary for many multicellular tissues, can be obtained. By, this way cellular movement in different directions by different cell types can be controlled. Such a system is described for the specific case of trachea regeneration, but it can be modified for other target organs. Analysis of cell migration and the possible methods for creating different pore gradients are elaborated. The next step in the analysis of such implants is their characterization after implantation. However, histological analysis of metallic implants is a long and cumbersome process, thus for monitoring host reaction to metallic implants in vivo an alternative method based on monitoring CGA and different

  14. Vortex dynamics equation in type-II superconductors in a temperature gradient

    International Nuclear Information System (INIS)

    Vega Monroy, R.; Sarmiento Castillo, J.; Puerta Torres, D.

    2010-01-01

    In this work we determined a vortex dynamics equation in a temperature gradient in the frame of the time dependent Ginzburg-Landau equation. In this sense, we derived a local solvability condition, which governs the vortex dynamics. Also, we calculated the explicit form for the force coefficients, which are the keys for the understanding of the balance equation due to vortex interactions with the environment. (author)

  15. Vortex dynamics equation in type-II superconductors in a temperature gradient

    Energy Technology Data Exchange (ETDEWEB)

    Vega Monroy, R.; Sarmiento Castillo, J. [Universidad del Atlantico, Barranquilla (Colombia). Facultad de Ciencias Basicas; Puerta Torres, D. [Universidad de Cartagena (Colombia). Facultad de Ciencias Exactas

    2010-12-15

    In this work we determined a vortex dynamics equation in a temperature gradient in the frame of the time dependent Ginzburg-Landau equation. In this sense, we derived a local solvability condition, which governs the vortex dynamics. Also, we calculated the explicit form for the force coefficients, which are the keys for the understanding of the balance equation due to vortex interactions with the environment. (author)

  16. Comprehensive biological effects of a complex field poly-metallic pollution gradient on the New Zealand mudsnail Potamopyrgus antipodarum (Gray)

    Energy Technology Data Exchange (ETDEWEB)

    Gust, M., E-mail: marion.gust@cemagref.fr [Cemagref, UR MALY, Laboratoire d' ecotoxicologie, 3b quai Chauveau, 69009 Lyon (France); AgroPariTech ENGREF, 19 avenue du Maine, F 75732 Paris (France); Buronfosse, T., E-mail: thierry.buronfosse@inserm.fr [Universite de Lyon, Laboratoire d' endocrinologie, Ecole Nationale Veterinaire de Lyon, avenue Bourgelat, 69280 Marcy l' Etoile (France); Geffard, O., E-mail: olivier.geffard@cemagref.fr [Cemagref, UR MALY, Laboratoire d' ecotoxicologie, 3b quai Chauveau, 69009 Lyon (France); Coquery, M., E-mail: marina.coquery@cemagref.fr [Cemagref, UR MALY, Laboratoire d' analyses physico-chimiques des milieux aquatiques, 3b quai Chauveau, 69009 Lyon (France); Mons, R., E-mail: raphael.mons@cemagref.fr [Cemagref, UR MALY, Laboratoire d' ecotoxicologie, 3b quai Chauveau, 69009 Lyon (France); Abbaci, K., E-mail: khedidja.abbaci@cemagref.fr [Cemagref, UR MALY, Laboratoire d' ecotoxicologie, 3b quai Chauveau, 69009 Lyon (France); Giamberini, L., E-mail: giamb@sciences.univ-metz.fr [Laboratoire des interactions Ecotoxicologie, Biodiversite, Ecosystemes, CNRS UMR 7146, campus Bridoux, 57000 Metz (France); Garric, J., E-mail: jeanne.garric@cemagref.fr [Cemagref, UR MALY, Laboratoire d' ecotoxicologie, 3b quai Chauveau, 69009 Lyon (France)

    2011-01-17

    The Lot River is known to be contaminated by metals, mainly cadmium and zinc, due to a former Zn ore treatment plant in the watershed of the Riou-Mort, a tributary of the Lot River. Many studies have been performed to characterize contamination, but few have assessed its consequences on the biological responses of organisms along the gradient. We exposed adult and juvenile New Zealand freshwater mudsnails Potamopyrgus antipodarum at several sites along the gradient of metal contamination for 28 days. Biological responses were monitored at different levels: individual (survival, growth and fecundity), tissue and biochemical (energy status and vertebrate-like sex steroid levels) to better understand the toxicity mechanisms involved. Accumulation of Cd and Zn was high during exposure. Most of the biological effects observed could be linked to this contamination and were concentration-dependent. Histological lesions of the digestive gland were observed, with hypertrophy of calcium cells and vacuolization of digestive cells. Such effects are likely to explain the decrease of energy status (triglycerides and proteins), juvenile growth and adult fecundity observed at the most polluted site. However the magnitude of the fall in fecundity cannot be attributed only to these tissular effects, indicating another mode of action of Cd or possible confounding factors. Steroid accumulation in snails indicated only organic pollution. Histopathological effects proved the most sensitive endpoint to metal (Cd and Zn) contamination.

  17. Trace metal concentrations in forest and lawn soils of Paris region (France) along a gradient of urban pressure

    Science.gov (United States)

    Ludovic, Foti

    2017-04-01

    concentrations and subsequent risks in soils of Paris and Paris region (Île-de-France). Our study aims at filling this knowledge gap, focusing on contamination and pollution by TMs in lawns and forests that constitute the main types of vegetation in urban areas of Paris region. Considering the rational described above, the aims of the present study were (i) to examine the concentration of eight selected TMs (As, Cd, Cr, Cu, Fe, Ni, Pb, Zn) in soils of two land-uses (public lawns and woods) along an urban pressure gradient in Paris region, (ii) to distinguish origins and sources of contamination or pollution, (iii) to evaluate the individual and overall TM contamination degree as well as the individual and overall TM pollution degree, (iiii) to use soil characteristics to better understand soil origins and histories along the urban pressure gradient and the relationship between these characteristics and TM concentrations. Ultimately, this study provides a baseline TM assessment for the long-term monitoring of the evolution of TM soil contents in urban area of the Paris region.

  18. INTEGRAL FIELD SPECTROSCOPY AND MULTI-WAVELENGTH IMAGING OF THE NEARBY SPIRAL GALAXY NGC 5668 : AN UNUSUAL FLATTENING IN METALLICITY GRADIENT

    Energy Technology Data Exchange (ETDEWEB)

    Marino, R. A.; Gil de Paz, A.; Castillo-Morales, A.; Perez-Gonzalez, P. G.; Gallego, J.; Zamorano, J. [CEI Campus Moncloa, UCM-UPM, Departamento de Astrofisica y CC. de la Atmosfera, Facultad de CC. Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Munoz-Mateos, J. C. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Sanchez, S. F. [Centro Astronomico Hispano Aleman, Calar Alto (CSIC-MPG), C/Jesus Durban Remon 2-2, E-04004 Almeria (Spain); Alonso-Herrero, A. [Instituto de Fisica de Cantabria, CSIC-UC, Avenida de los Castros s/n, 39005 Santander (Spain); Boissier, S., E-mail: ramarino@fis.ucm.es [Laboratoire dAstrophysique de Marseille, OAMP, Universite Aix-Marseille and CNRS UMR 6110, 38 rue Frederic Joliot-Curie, 13388 Marseille cedex 13 (France)

    2012-07-20

    We present an analysis of the full bidimensional optical spectral cube of the nearby spiral galaxy NGC 5668, observed with the Pmas fiber PAcK Integral Field Unit (IFU) at the Calar Alto observatory 3.5 m telescope. We make use of broadband imaging to provide further constraints on the evolutionary history of the galaxy. This data set will allow us to improve our understanding of the mechanisms that drive the evolution of disks. We investigated the properties of 62 H II regions and concentric rings in NGC 5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that while inward of r {approx}36'' {approx} 4.4 kpc {approx} 0.36 (D{sub 25}/2) the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r {approx} 36'' flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC 5668 is performed by fitting these profiles with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks. From this, we infer a spin and circular velocity of {lambda} = 0.053 and v{sub c} = 167 km s{sup -1}, respectively. The metallicity gradient and rotation curve predicted by this best-fitting galaxy model nicely match the values derived from the IFU observations, especially within r {approx}36''. The same is true for the colors despite some small offsets and a reddening in the bluest colors beyond that radius. On the other hand, deviations of some of these properties in the outer disk indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC 5668.

  19. INTEGRAL FIELD SPECTROSCOPY AND MULTI-WAVELENGTH IMAGING OF THE NEARBY SPIRAL GALAXY NGC 5668 : AN UNUSUAL FLATTENING IN METALLICITY GRADIENT

    International Nuclear Information System (INIS)

    Marino, R. A.; Gil de Paz, A.; Castillo-Morales, A.; Pérez-González, P. G.; Gallego, J.; Zamorano, J.; Muñoz-Mateos, J. C.; Sánchez, S. F.; Alonso-Herrero, A.; Boissier, S.

    2012-01-01

    We present an analysis of the full bidimensional optical spectral cube of the nearby spiral galaxy NGC 5668, observed with the Pmas fiber PAcK Integral Field Unit (IFU) at the Calar Alto observatory 3.5 m telescope. We make use of broadband imaging to provide further constraints on the evolutionary history of the galaxy. This data set will allow us to improve our understanding of the mechanisms that drive the evolution of disks. We investigated the properties of 62 H II regions and concentric rings in NGC 5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that while inward of r ∼36'' ∼ 4.4 kpc ∼ 0.36 (D 25 /2) the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r ∼ 36'' flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC 5668 is performed by fitting these profiles with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks. From this, we infer a spin and circular velocity of λ = 0.053 and v c = 167 km s –1 , respectively. The metallicity gradient and rotation curve predicted by this best-fitting galaxy model nicely match the values derived from the IFU observations, especially within r ∼36''. The same is true for the colors despite some small offsets and a reddening in the bluest colors beyond that radius. On the other hand, deviations of some of these properties in the outer disk indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC 5668.

  20. A new macroscopically anisotropic pressure dependent yield function for metal matrix composite based on strain gradient plasticity for the microstructure

    DEFF Research Database (Denmark)

    Azizi, Reza; Legarth, Brian Nyvang; Niordson, Christian Frithiof

    2013-01-01

    Metal matrix composites with long aligned elastic fibers are studied using an energetic rate independent strain gradient plasticity theory with an isotropic pressure independent yield function at the microscale. The material response is homogenized to obtain a conventional macroscopic model...... is investigated numerically using a unit cell model with periodic boundary conditions containing a single fiber deformed under generalized plane strain conditions. The homogenized response can be modeled by conventional plasticity with an anisotropic yield surface and a free energy depending on plastic strain...

  1. Functional and compositional responses in soil microbial communities along two metal pollution gradients: does the level of historical pollution affect resistance against secondary stress?

    NARCIS (Netherlands)

    Azarbad, H.; Niklinska, M.; Nikiel, K.; van Straalen, N.M.; Röling, W.F.M.

    2015-01-01

    We examined how the exposure to secondary stressors affected the functional and compositional responses of microbial communities along two metal pollution gradients in Polish forests and whether responses were influenced by the level of metal pollution. Basal respiration rate and community

  2. Synthesis, spectral characterization thermal stability, antimicrobial studies and biodegradation of starch–thiourea based biodegradable polymeric ligand and its coordination complexes with [Mn(II, Co(II, Ni(II, Cu(II, and Zn(II] metals

    Directory of Open Access Journals (Sweden)

    Nahid Nishat

    2016-09-01

    Full Text Available A biodegradable polymer was synthesized by the modification reaction of polymeric starch with thiourea which is further modified by transition metals, Mn(II, Co(II, Ni(II, Cu(II and Zn(II. All the polymeric compounds were characterized by (FT-IR spectroscopy, 1H NMR spectroscopy, 13C NMR spectroscopy, UV–visible spectra, magnetic moment measurements, thermogravimetric analysis (TGA and antibacterial activities. Polymer complexes of Mn(II, Co(II and Ni(II show octahedral geometry, while polymer complexes of Cu(II and Zn(II show square planar and tetrahedral geometry, respectively. The TGA revealed that all the polymer metal complexes are more thermally stable than their parental ligand. In addition, biodegradable studies of all the polymeric compounds were also carried out through ASTM-D-5338-93 standards of biodegradable polymers by CO2 evolution method which says that coordination decreases biodegradability. The antibacterial activity was screened with the agar well diffusion method against some selected microorganisms. Among all the complexes, the antibacterial activity of the Cu(II polymer–metal complex showed the highest zone of inhibition because of its higher stability constant.

  3. Manganese(II), iron(II), and mixed-metal metal-organic frameworks based on chains with mixed carboxylate and azide bridges: magnetic coupling and slow relaxation.

    Science.gov (United States)

    Wang, Yan-Qin; Yue, Qi; Qi, Yan; Wang, Kun; Sun, Qian; Gao, En-Qing

    2013-04-15

    Mn(II) and Fe(II) compounds derived from azide and the zwitterionic 1-carboxylatomethylpyridinium-4-carboxylate ligand are isomorphous three-dimensional metal-organic frameworks (MOFs) with the sra net, in which the metal ions are connected into anionic chains by mixed (μ-1,1-azide)bis(μ-carboxylate) triple bridges and the chains are cross-linked by the cationic backbones of the zwitterionic ligands. The Mn(II) MOFs display typical one-dimensional antiferromagnetic behavior. In contrast, with one more d electron per metal center, the Fe(II) counterpart shows intrachain ferromagnetic interactions and slow relaxation of magnetization attributable to the single-chain components. The activation energies for magnetization reversal in the infinite- and finite-chain regimes are Δτ1 = 154 K and Δτ2 = 124 K, respectively. Taking advantage of the isomorphism between the Mn(II) and Fe(II) MOFs, we have prepared a series of mixed-metal Mn(II)(1-x)Fe(II)(x) MOFs with x = 0.41, 0.63, and 0.76, which intrinsically feature random isotropic/anisotropic sites and competing antiferromagnetic-ferromagnetic interactions. The materials show a gradual antiferromagnetic-to-ferromagnetic evolution in overall behaviors as the Fe(II) content increases, and the Fe-rich materials show complex relaxation processes that may arise for mixed SCM and spin-glass mechanisms. A general trend is that the activation energy and the blocking temperature increase with the Fe(II) content, emphasizing the importance of anisotropy for slow relaxation of magnetization.

  4. Heavy metal / polyacid interaction : an electrochemical study of the binding of Cd(II), Pb(II) and Zn(II) to polycarboxylic and humic acids

    NARCIS (Netherlands)

    Cleven, R.F.M.J.

    1984-01-01

    Polyelectrolyte effects in the interaction of heavy metal ions with model polycarboxylic acids have been described, in order to establish the relevance of these effects in the interaction of heavy metal ions with naturally occurring humic and fulvic acids. The model systems consisted of Cd(II),

  5. Spatial Gradients in Trace Metal Concentrations in the Surface Microlayer of the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    Antonio eTovar-Sanchez

    2014-12-01

    Full Text Available The relationship between dust deposition and surface water metal concentrations is poorly understood. Dissolution, solubility, and partitioning reactions of trace metals from dust particles are governed by complex chemical, biological, and physical processes occurring in the surface ocean. Despite that, the role of the sea surface microlayer (SML, a thin, but fundamental component modulating the air-sea exchange of materials has not been properly evaluated. Our study revealed that the SML of the Mediterranean Sea is enriched with bioactive trace metals (i.e., Cd, Co, Cu and Fe, ranging from 8 (for Cd to 1000 (for Fe times higher than the dissolved metal pool in the underlying water column. The highest enrichments were spatially correlated with the atmospheric deposition of mineral particles. Our mass balance results suggest that the SML in the Mediterranean Sea contains about 2 tonnes of Fe. However, we did not detect any trends between the concentrations of metals in SML with the subsurface water concentrations and biomass distributions. These findings suggest that future studies are needed to quantify the rate of metal exchange between the SML and the bioavailable pool and that the SML should be considered to better understand the effect of atmospheric inputs on the biogeochemistry of trace metals in the ocean.

  6. Synthesis, characterization and biological studies of metal complexes of Co (II), Ni (II), Cu (II), Zn (II) with sulphadimidine-benzylidene

    International Nuclear Information System (INIS)

    Tahira, F.; Imran, M.; Iqbal, J.

    2009-01-01

    Some novel complexes of Co (II), Ni (II), Cu (II), and Zn (II) have been synthesized with a Schiff base ligand derived from sulphadimidine and benzaldehyde. The structural features of the complexes have been determined by elemental analysis, magnetic susceptibility, conductance measurement, UV/ Vis. and infrared spectroscopy. IR studies revealed that the Schiff base ligand Sulphadimidine-benzylidene has monoanionic bidendate nature and coordinate with metal ions through nitrogen atom of azomethine (>C = N) and deprotonated -NH group. All the complexes were assigned octahedral geometry on the basis of magnetic moment and electronic spectroscopic data. Low value of conductance supports their non-electrolytic nature. The ligand, as well as its complexes were checked for their in vitro antimicrobial activities against two gram positive bacterial strains, Bacillus subtillus. Staphylococcus aureus and one gram negative Salmonella typhae and five fungal strains, Nigrospora oryzae, Curvularia lunata, Drechslera rostrata, Aspergillus niger and Candida olbicans by disc diffusion method and agar plate technique, respectively. Both the antibacterial and antitungal activities of the synthesized metal complexes were found to be more as compared to parent drug and uncomplexed ligand. All the complexes contain coordinated water, which is lost at 141-160 degree C. (author)

  7. SMC west halo: a slice of the galaxy that is being tidally stripped?. Star clusters trace age and metallicity gradients

    Science.gov (United States)

    Dias, B.; Kerber, L.; Barbuy, B.; Bica, E.; Ortolani, S.

    2016-06-01

    Context. The evolution and structure of the Magellanic Clouds is currently under debate. The classical scenario in which both the Large and Small Magellanic Clouds (LMC, SMC) are orbiting the Milky Way has been challenged by an alternative in which the LMC and SMC are in their first close passage to our Galaxy. The clouds are close enough to us to allow spatially resolved observation of their stars, and detailed studies of stellar populations in the galaxies are expected to be able to constrain the proposed scenarios. In particular, the west halo (WH) of the SMC was recently characterized with radial trends in age and metallicity that indicate tidal disruption. Aims: We intend to increase the sample of star clusters in the west halo of the SMC with homogeneous age, metallicity, and distance derivations to allow a better determination of age and metallicity gradients in this region. Positions are compared with the orbital plane of the SMC from models. Methods: Comparisons of observed and synthetic V(B-V) colour-magnitude diagrams were used to derive age, metallicity, distance, and reddening for star clusters in the SMC west halo. Observations were carried out using the 4.1 m SOAR telescope. Photometric completeness was determined through artificial star tests, and the members were selected by statistical comparison with a control field. Results: We derived an age of 1.23 ± 0.07 Gyr and [Fe/H] = -0.87 ± 0.07 for the reference cluster NGC 152, compatible with literature parameters. Age and metallicity gradients are confirmed in the WH: 2.6 ± 0.6 Gyr/° and -0.19 ± 0.09 dex/°, respectively. The age-metallicity relation for the WH has a low dispersion in metallicity and is compatible with a burst model of chemical enrichment. All WH clusters seem to follow the same stellar distribution predicted by dynamical models, with the exception of AM-3, which should belong to the counter-bridge. Brück 6 is the youngest cluster in our sample. It is only 130 ± 40 Myr old and

  8. Temporal variability of biodiversity patterns and trophic structure of estuarine macrobenthic assemblages along a gradient of metal contamination

    KAUST Repository

    Piló, D.

    2015-06-01

    The present study aimed to investigate the response of macrobenthic assemblages along a gradient of metal contamination using a combination of uni- and multivariate methods focusing on their composition, structure and function. A total of six sites were established based on a preliminary survey, which identified three areas with different levels of contamination. These areas were defined as slightly contaminated (SC), moderately contaminated (MC) and highly contaminated (HC). Each area comprised two sites, sampled in four sampling surveys (September 2012, February, May and October of 2013). To investigate the response of the macrobenthic assemblages the number of individuals (N), number of taxa (S), Shannon-Weaver diversity (H\\'), Pielou\\'s equitability (J\\') and different distance-based multivariate measures of β-diversity (complementarity) were analysed. β-diversity as turnover was also analysed together with spatial and temporal changes in the trophic structure. A clear gradient of increasing contamination was consistently detected, but comparisons with available sediment quality guidelines indicated that adverse biological effects may be expected in all areas. This result suggests measuring concentrations of contaminants in the sediment per se may be insufficient to establish a clear link between ecological patterns and the contamination of the system. Also it highlights the difficulty of identifying reference areas in highly urbanized and industrialized estuaries. Only multivariate analysis (dbRDA; both using the taxonomic and trophic composition) and β-diversity as turnover showed a consistent response to metal contamination. Higher heterogeneity, mainly due to contribution of rare species (i.e. species present in a single sampling period), was observed in the least contaminated area (SC), decreasing towards the HC. In terms of the trophic function, a shift from a dominance of carnivores in the SC to the dominance of deposit-feeding organisms (and

  9. Temporal variability of biodiversity patterns and trophic structure of estuarine macrobenthic assemblages along a gradient of metal contamination

    KAUST Repository

    Piló , D.; Pereira, F.; Carriç o, A.; Curdia, Joao; Pereira, P.; Gaspar, M. B.; Gaspar, M. B.; Carvalho, Susana

    2015-01-01

    The present study aimed to investigate the response of macrobenthic assemblages along a gradient of metal contamination using a combination of uni- and multivariate methods focusing on their composition, structure and function. A total of six sites were established based on a preliminary survey, which identified three areas with different levels of contamination. These areas were defined as slightly contaminated (SC), moderately contaminated (MC) and highly contaminated (HC). Each area comprised two sites, sampled in four sampling surveys (September 2012, February, May and October of 2013). To investigate the response of the macrobenthic assemblages the number of individuals (N), number of taxa (S), Shannon-Weaver diversity (H'), Pielou's equitability (J') and different distance-based multivariate measures of β-diversity (complementarity) were analysed. β-diversity as turnover was also analysed together with spatial and temporal changes in the trophic structure. A clear gradient of increasing contamination was consistently detected, but comparisons with available sediment quality guidelines indicated that adverse biological effects may be expected in all areas. This result suggests measuring concentrations of contaminants in the sediment per se may be insufficient to establish a clear link between ecological patterns and the contamination of the system. Also it highlights the difficulty of identifying reference areas in highly urbanized and industrialized estuaries. Only multivariate analysis (dbRDA; both using the taxonomic and trophic composition) and β-diversity as turnover showed a consistent response to metal contamination. Higher heterogeneity, mainly due to contribution of rare species (i.e. species present in a single sampling period), was observed in the least contaminated area (SC), decreasing towards the HC. In terms of the trophic function, a shift from a dominance of carnivores in the SC to the dominance of deposit-feeding organisms (and

  10. Relations between metals (Zn, Pb, Cd and Cu) and glutathione-dependent detoxifying enzymes in spiders from a heavy metal pollution gradient

    International Nuclear Information System (INIS)

    Wilczek, Grazyna; Babczynska, Agnieszka; Augustyniak, Maria; Migula, Pawel

    2004-01-01

    We studied the relations between glutathione-dependent detoxifying enzymes and heavy metal burdens in the web-building spider Agelena labyrinthica (Agelenidae) and the wolf spider Pardosa lugubris (Lycosidae) from five meadow sites along a heavy metal pollution gradient. We assayed the activity of glutathione-S-transferase (GST) and glutathione peroxidases (GPOX, GSTPx), and glutathione (GSH) levels in both sexes. Except for GSH vs Pb content, we found significant correlations between GPOX and GSTPx activity and metal concentrations in females of A. labyrinthica. The highest activity of these enzymes measured in the web-building spiders was found in the individuals from the most polluted sites. In P. lugubris males significant correlations were found between GST and Pb and Zn concentrations, and between GPOX and GSTPx and the concentration of Cu. GST activity was higher in males collected from less polluted areas. Thus, detoxifying strategies against pollutants seemed to be sex-dependent. Actively hunting spiders had higher metal concentrations, maintaining lower activity of detoxifying enzymes and a lower glutathione level. - Capsule: Glutathione-linked enzyme activity in spiders from polluted areas depends on hunting strategy and sex

  11. Relations between metals (Zn, Pb, Cd and Cu) and glutathione-dependent detoxifying enzymes in spiders from a heavy metal pollution gradient

    Energy Technology Data Exchange (ETDEWEB)

    Wilczek, Grazyna [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland); Babczynska, Agnieszka [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland); Augustyniak, Maria [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland); Migula, Pawel [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland)]. E-mail: migula@us.edu.pl

    2004-12-01

    We studied the relations between glutathione-dependent detoxifying enzymes and heavy metal burdens in the web-building spider Agelena labyrinthica (Agelenidae) and the wolf spider Pardosa lugubris (Lycosidae) from five meadow sites along a heavy metal pollution gradient. We assayed the activity of glutathione-S-transferase (GST) and glutathione peroxidases (GPOX, GSTPx), and glutathione (GSH) levels in both sexes. Except for GSH vs Pb content, we found significant correlations between GPOX and GSTPx activity and metal concentrations in females of A. labyrinthica. The highest activity of these enzymes measured in the web-building spiders was found in the individuals from the most polluted sites. In P. lugubris males significant correlations were found between GST and Pb and Zn concentrations, and between GPOX and GSTPx and the concentration of Cu. GST activity was higher in males collected from less polluted areas. Thus, detoxifying strategies against pollutants seemed to be sex-dependent. Actively hunting spiders had higher metal concentrations, maintaining lower activity of detoxifying enzymes and a lower glutathione level. - Capsule: Glutathione-linked enzyme activity in spiders from polluted areas depends on hunting strategy and sex.

  12. SEPARATION OF Fe (III, Cr(III, Cu(II, Ni(II, Co(II, AND Pb(II METAL IONS USING POLY(EUGENYL OXYACETIC ACID AS AN ION CARRIER BY A LIQUID MEMBRANE TRANSPORT METHOD

    Directory of Open Access Journals (Sweden)

    La Harimu

    2010-06-01

    Full Text Available Fe (III, Cr(III, Cu(II, Ni(II, Co(II, and Pb(II  metal ions had been separated using poly(eugenyl oxyacetic acid as an ion carrier by bulk liquid membrane transport method. The effect of pH, polyeugenyl oxyacetic acid ion carrier concentration, nitric acid concentration in the stripping solution, transport time, and metal concentration were optimized. The result showed that the optimum condition for transport of metal ions was at pH 4 for ion Fe(III and at pH 5 for Cr(III, Cu(II, Ni(II, Co(II, and Pb(II ions. The carrier volumes were optimum with concentration of 1 x 10-3 M at 7.5 mL for Cr(III, Cu (II,  Ni(II, Co(II ions and at 8.5 mL for Fe(III and Pb(II ions. The concentration of HNO3 in stripping phase was optimum at 2 M for Fe(III and Cu(II ions, 1 M for Cr(III, Ni(II and Co(II ions, and 0.5 M for Pb(II ion. The optimum transport times were 36 h for Fe(III and Co(II ions, and 48 h for Cr(III, Cu (II, Ni(II, and Pb(II ions. The concentration of metal ions accurately transported were 2.5 x 10-4 M for Fe(III and Cr(III ions, and 1 M for Cu (II, Ni(II, Co(II, and Pb(II ions. Compared to other metal ions the transport of Fe(III was the highest with selectivity order of Fe(III > Cr(III > Pb(II > Cu(II > Ni(II > Co(II. At optimum condition, Fe(III ion was transported through the membrane at 46.46%.   Keywords: poly(eugenyl oxyacetic acid, transport, liquid membrane, Fe (III, Cr(III, Cu(II, Ni(II, Co(II, and Pb(II ions

  13. Numerical simulations of type II gradient drift irregularities in the equatorial electrojet

    International Nuclear Information System (INIS)

    Ferch, R.L.; Sudan, R.N.

    1977-01-01

    Two-dimensional numerical studies of the development of type II irregularities in the equatorial electrojet have been carried out using a method similar to that of McDonald et al., (1974) except that ion inertia has been neglected. This simplification is shown to be a valid approximation whenever the electron drift velocity is small in comparison with the ion acoustic velocity and the values of the other parameters are those appropriate for the equatorial E layer. This code enables us to follow the development of quasi-steady state turbulence from appropriate initial pertubations. The two-dimensional turbulent spectrum of electron density perturbations excited is studied both for the case of devlopment from initial perturbations and for the case of a continuously pumped single driving wave

  14. Micellar effect on metal-ligand complexes of Co(II, Ni(II, Cu(II and Zn(II with citric acid

    Directory of Open Access Journals (Sweden)

    Nageswara Rao Gollapalli

    2009-12-01

    Full Text Available Chemical speciation of citric acid complexes of Co(II, Ni(II, Cu(II and Zn(II was investigated pH-metrically in 0.0-2.5% anionic, cationic and neutral micellar media. The primary alkalimetric data were pruned with SCPHD program. The existence of different binary species was established from modeling studies using the computer program MINIQUAD75. Alkalimetric titrations were carried out in different relative concentrations (M:L:X = 1:2:5, 1:3:5, 1:5:3 of metal (M to citric acid. The selection of best chemical models was based on statistical parameters and residual analysis. The species detected were MLH, ML2, ML2H and ML2H2. The trend in variation of stability constants with change in mole fraction of the medium is explained on the basis of electrostatic and non-electrostatic forces. Distributions of the species with pH at different compositions of micellar media are also presented.

  15. Susceptibility to a metal under global warming is shaped by thermal adaptation along a latitudinal gradient.

    Science.gov (United States)

    Dinh Van, Khuong; Janssens, Lizanne; Debecker, Sara; De Jonge, Maarten; Lambret, Philippe; Nilsson-Örtman, Viktor; Bervoets, Lieven; Stoks, Robby

    2013-09-01

    Global warming and contamination represent two major threats to biodiversity that have the potential to interact synergistically. There is the potential for gradual local thermal adaptation and dispersal to higher latitudes to mitigate the susceptibility of organisms to contaminants and global warming at high latitudes. Here, we applied a space-for-time substitution approach to study the thermal dependence of the susceptibility of Ischnura elegans damselfly larvae to zinc in a common garden warming experiment (20 and 24 °C) with replicated populations from three latitudes spanning >1500 km in Europe. We observed a striking latitude-specific effect of temperature on the zinc-induced mortality pattern; local thermal adaptation along the latitudinal gradient made Swedish, but not French, damselfly larvae more susceptible to zinc at 24 °C. Latitude- and temperature-specific differences in zinc susceptibility may be related to the amount of energy available to defend against and repair damage since Swedish larvae showed a much stronger zinc-induced reduction of food intake at 24 °C. The pattern of local thermal adaptation indicates that the predicted temperature increase of 4 °C by 2100 will strongly magnify the impact of a contaminant such as zinc at higher latitudes unless there is thermal evolution and/or migration of lower latitude genotypes. Our results underscore the critical importance of studying the susceptibility to contaminants under realistic warming scenarios taking into account local thermal adaptation across natural temperature gradients. © 2013 John Wiley & Sons Ltd.

  16. Polarization field gradient effects in inhomogeneous metal-ferroelectric bilayers: Optical response and band gap tunability

    Energy Technology Data Exchange (ETDEWEB)

    Vivas C, H., E-mail: hvivasc@unal.edu.co [Grupo de las Propiedades Opticas de los Materiales (POM), Departamento de Fisica, Universidad Nacional de Colombia, Sede Manizales, A.A. 127 (Colombia); Vargas-Hernandez, C. [Grupo de las Propiedades Opticas de los Materiales (POM), Departamento de Fisica, Universidad Nacional de Colombia, Sede Manizales, A.A. 127 (Colombia)

    2012-06-15

    Optical constants, reflectivity response and direct band gap energy (E{sub g}{sup d}) were calculated and simulated by developing an electrodynamic-based model for a three medium system, namely vacuum/ferroelectric film/metallic substrate. Depolarization effects due to the contact between the metallic substrate and the FE film, as well as the spatially dependent profile of the dielectric susceptibility {epsilon}(z) enter into the formalism by adapting the phenomenological Landau-Ginzburg-Devonshire theory (LGD). Absorption coefficient is obtained from the Lambert-Beer-Bouguer (LBB) approximation and the direct band gap energy as a function of the characteristic length is calculated by using the general Tauc power law. Numerical simulations lead to range of values for tunable E{sub g}{sup d} from 2.6 to 2.8 eV for characteristic lengths up to 30% the thickness of the film, in concordance with recent reports.

  17. Comparison of methods for measuring flux gradients in type II superconductors

    International Nuclear Information System (INIS)

    Kroeger, D.M.; Koch, C.C.; Charlesworth, J.P.

    1975-01-01

    A comparison has been made of four methods of measuring the critical current density J/sub c/ in hysteretic type II superconductors, having a wide range of K and J/sub c/ values, in magnetic fields up to 70 kOe. Two of the methods, (a) resistive measurements and (b) magnetization measurements, were carried out in static magnetic fields. The other two methods involved analysis of the response of the sample to a small alternating field superimposed on the static field. The response was analyzed either (c) by measuring the third-harmonic content or (d) by integration of the waveform to obtain measure of flux penetration. The results are discussed with reference to the agreement between the different techniques and the consistency of the critical state hypothesis on which all these techniques are based. It is concluded that flux-penetration measurements by method (d) provide the most detailed information about J/sub c/ but that one must be wary of minor failures of the critical state hypothesis. Best results are likely to be obtained by using more than one method. (U.S.)

  18. The Formation of Metal (M=Co(II), Ni(II), and Cu(II)) Complexes by Aminosilanes Immobilized within Mesoporous Molecular Sieves

    International Nuclear Information System (INIS)

    Park, Dong Ho; Park, Sung Soo; Choe, Sang Joon

    1999-01-01

    The immobilization of APTMS(3-(2-aminoethylamino)propyltrimethoxysilane) and AAPTMS(3-(2-(2-aminoethyl) aminoethylamino)propyltrimethoxysilane) on the surface of high quality mesoporous molecular sieves MCM-41 and MCM-48 have been confirmed by F.T.-IR spectroscopy, Raman spectroscopy, 29 Si solid state NMR, and a surface polarity measurement using Reichardt's dye. The formation of metal (Co(II), Ni(II), and Cu(II)) complexes by immobilized aminosilanes have been investigated by photoacoustic spectroscopy(PAS). The assignment of UV-Vis. PAS bands makes it possible to identify the structure of metal complexes within mesoporous molecular sieves. Co(II) ion may be coordinated mainly in a tetrahedral symmetry by two APTMS onto MCM-41, and in an octahedral one by two AAPTMS. Both Ni(II) and Cu(II) coordinated by aminosilanes within MCM-41 form possibly the octahedral complexes such as [Ni(APTMS) 2 (H 2 O) 2 ] 2+ , [Ni(AAPTMS) 2 ] 2+ , [Cu(APTMS) 2 (H 2 O) 2 ] 2+ , and [Cu(AAPTMS)(H 2 O) 3 ] 2+ , respectively. The PAS band shapes of complexes onto MCM-48 are similar to those of corresponding MCM-41 with the variation of PAS intensity. Most of metal ion(II) within MCM-41 and MCM-48 are coordinated by aminosilanes without the impregnation on the surface

  19. Metal Mesh Filters for Terahertz Receivers, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The technical objective of this SBIR program is to develop and demonstrate metal mesh filters for use in NASA's low noise receivers for terahertz astronomy and...

  20. Metal Rubber Sensor Appliqus for Rotor Blade Air, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Thin film Metal RubberTM sensor appliqués have the potential to reduce the time, complexity and cost of measuring air flow-induced skin friction during the...

  1. studies on transition metal complexes of herbicidal compounds. ii

    African Journals Online (AJOL)

    a

    derivative of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine, atrazine (ATZ) --- a well known herbicide has ... development while the other is the metal ion associated degradation or deactivation of the herbicides .... Colour M.p./decomp.

  2. Transition metal M(II complexes with isonicotinoylhydrazone-9-anthraldehyde

    Directory of Open Access Journals (Sweden)

    Dianu M.L.

    2010-01-01

    Full Text Available New complexes of isonicotinoylhydrazone-9-anthraldehyde with Cu(II, Co(II and Ni(II have been prepared and characterized by analytical and physico-chemical techniques, such as elemental and thermal analyses, magnetic susceptibility and conductivity measurements, and electronic, EPR and IR spectral studies. The infrared spectral studies revealed the bidentate or monodentate nature of the Schiff base in the complexes; the pyridine nitrogen does not participate in the coordination. A tetrahedral geometry is suggested for the nitrate-complexes and an octahedral geometry for the others. Thermal studies support the chemical formulation of these complexes.

  3. Adsorption of Cd(II) Metal Ion on Adsorbent beads from Biomass Saccharomycess cereviceae - Chitosan

    Science.gov (United States)

    Hasri; Mudasir

    2018-01-01

    The adsorbent beads that was preparation from Saccharomycess cereviceae culture strain FN CC 3012 and shrimp shells waste and its application for adsorption of Cd (II) metal ion has been studied. The study start with combination of Saccharomycess cereviceae biomass to chitosan (Sc-Chi), contact time, pH of solution and initial concentration of cations. Total Cd(II) metal ion adsorbed was calculated from the difference of metal ion concentration before and after adsorption by AAS. The results showed that optimum condition for adsorption of Cd(II) ions by Sc-Chi beads was achieved with solution pH of 4, contact time of 60 minutes and initial concentration adsorption 100mg/L. The hydroxyl (-OH) and amino (-NH2) functional groups were believed to be responsible for the adsorption of Cd(II) ions.

  4. Improved Metal-Polymeric Laminate Radiation Shielding, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In this proposed Phase II program, builds on the phase I feaibility where a multifunctional lightweight radiation shield composite was developed and fabricated. This...

  5. Synthesis and structural characterisation of iron(II) and copper(II) diphosphates containing flattened metal oxotetrahedra

    International Nuclear Information System (INIS)

    Keates, Adam C.; Wang, Qianlong; Weller, Mark T.

    2014-01-01

    Single crystal and bulk polycrystalline forms of K 2 MP 2 O 7 (M=Fe(II), Cu(II)) have been synthesised and their structures determined from single crystal X-ray diffraction data. Both compounds crystallize in the tetragonal system, space group P-42 1 m. Their structures are formed from infinite sheets of linked oxopolyhedra of the stoichiometry [MP 2 O 7 ] 2− with potassium cations situated between the layers. The MO 4 tetrahedra share oxygen atoms with [P 2 O 7 ] 4− diphosphate groups and the potassium ions have KO 8 square prismatic geometry. In both compounds the M(II) centre has an unusual strongly flattened, tetrahedral coordination to oxygen, as a result of the Jahn–Teller (JT) effect for the high spin d 6 Fe(II) and p-orbital mixing or a second order JT effect for d 9 Cu(II) centres in four fold coordination. The uncommon transition metal ion environments found in these materials are reflected in their optical absorption spectra and magnetism data. - Graphical abstract: The structures of the tetragonal polymorphs of K 2 MP 2 O 7 , M=Cu(II), Fe(II), consist of infinite sheets of stoichiometry [MP 2 O 7 ] 2− , formed from linked pyrophosphate groups and MO 4 tetrahedra, separated by potassium ions. In both compounds the unusual tetrahedral coordination of the M(II) centre is strongly flattened as a result of Jahn–Teller (JT) effects for high spin, d 6 Fe(II) and p-orbital mixing and second-order JT effects for d 9 Cu(II). Display Omitted - Highlights: • Tetrahedral copper and iron(II) coordinated by oxygen. • New layered phosphate structure. • Jahn–Teller and d 10 distorted coordinations

  6. Removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution using rice husk-based activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Taha, Mohd F., E-mail: faisalt@petronas.com.my; Shaharun, Maizatul S. [Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750, Perak Darul Ridzuan (Malaysia); Shuib, Anis Suhaila, E-mail: anisuha@petronas.com.my; Borhan, Azry [Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750, Perak Darul Ridzuan (Malaysia)

    2014-10-24

    An attempt was made to investigate the potential of rice husk-based activated carbon as an alternative low-cost adsorbent for the removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Rice husk-based activated carbon was prepared via treatment of rice husk with NaOH followed by the carbonization process at 400°C for 2 hours. Three samples, i.e. raw rice husk, rice husk treated with NaOH and rice husk-based activated carbon, were analyzed for their morphological characteristics using field-emission scanning electron microscope/energy dispersive X-ray (FESEM/EDX). These samples were also analyzed for their carbon, hydrogen, nitrogen, oxygen and silica contents using CHN elemental analyzer and FESEM/EDX. The porous properties of rice husk-based activated carbon were determined by Brunauer-Emmett-Teller (BET) surface area analyzer, and its surface area and pore volume were 255 m{sup 2}/g and 0.17 cm{sup 2}/g, respectively. The adsorption studies for the removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution were carried out at a fixed initial concentration of metal ion (150 ppm) with variation amount of adsorbent (rice husk-based activated carbon) as a function of varied contact time at room temperature. The concentration of each metal ion was analyzed using atomic absorption spectrophotometer (AAS). The results obtained from adsorption studies indicate the potential of rice husk as an economically promising precursor for the preparation of activated carbon for removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Isotherm and kinetic model analyses suggested that the experimental data of adsorption studies fitted well with Langmuir, Freundlich and second-order kinetic models.

  7. Bird diversity and dissimilarity show contrasting patterns along heavy metal pollution gradients in the Urals, Russia.

    Science.gov (United States)

    Belskii, Eugen A; Mikryukov, Vladimir S

    2018-05-07

    The effects of industrial pollution on bird diversity have been widely studied using traditional diversity measures, which assume all species to be equivalent. We compared species richness and Shannon index with distance-based measures of taxonomic, functional, and phylogenetic diversity (the abundance-weighted mean nearest taxon distances), which describe within-community dissimilarity at terminal branches. Analysis of dissimilarity can shed light on the processes underlying community assembly, i.e., environmental filtering decreases dissimilarity whereas competitive exclusion increases it. In the 2-year study near Karabash and Revda copper smelters in Russia, point counts of nesting birds and habitat descriptions were taken at 10 sites (40 plots) along each pollution gradient. The abundance and diversity of birds showed good repeatability in both regions. The total density of birds, number of species per plot, and Shannon diversity decreased at high toxic load in both regions. The taxonomic, functional, and phylogenetic nearest taxon distances showed the same pattern within regions. Species dissimilarity within communities increased with pollution in Karabash (due to loss of functionally similar species), but did not change in Revda (due to mass replacement of forest species by species of open habitats). Pollution-induced changes in bird communities near Karabash were greater due to the stronger deterioration of the forest ecosystems and less favorable natural conditions (more arid climate, lower diversity and vitality of the tree stand and understorey) compared to Revda. This study emphasizes the need for a multi-level approach to the analysis of bird communities using traditional indices of diversity, functional, taxonomic, or phylogenetic distances between species and environmental variables.

  8. Simultaneous measurement of trace metal and oxyanion concentrations in water using diffusive gradients in thin films with a chelex-metsorb mixed binding layer

    DEFF Research Database (Denmark)

    Panther, Jared G.; Bennett, William W.; Welsh, David T.

    2014-01-01

    A new diffusive gradients in thin films (DGT) technique with a mixed binding layer (Chelex-100 and the titanium dioxide based adsorbent Metsorb) is described for the simultaneous measurement of labile trace metal (Mn, Co, Ni, Cu, Cd, and Pb) and oxyanion (V, As, Mo, Sb, W, and P) concentrations i...

  9. Studying of metals distribution in the Pinus Sylvestris bark and needles in a zone of influence the gradient polluted air stream from Cu-smelter

    International Nuclear Information System (INIS)

    Aminov, P.G.; Lonshchakova, G.F.

    2008-01-01

    In the paper the features of accumulation for heavy metals by pine needles and bark in the gradient dispersion area of technogenic elements and using of the bark as the bioindicator to establish influencing zones of smelter on environment are represented

  10. Stress Proteins (hsp70, hsp60) Induced in Isopods and Nematodes by Field Exposure to Metals in a Gradient near Avonmouth, UK

    NARCIS (Netherlands)

    Arts, M.S.J.; Schill, R.O.; Knigge, T.; Eckwert, H.; Kammenga, J.E.; Köhler, H.R.

    2004-01-01

    Heat shock proteins (hsps) are potential biomarkers for monitoring environmental pollution. In this study, the use of hsps as biomarkers in field bioassays was evaluated in terrestrial invertebrates exposed to a metal gradient near Avonmouth, UK. We investigated the hsp70 response in resident and

  11. Electronic Structure of Rare-Earth Metals. II. Positron Annihilation

    DEFF Research Database (Denmark)

    Williams, R. W.; Mackintosh, Allan

    1968-01-01

    of Loucks shows that the independent-particle model gives a good first approximation to the angular distribution, although correlation effects probably smear out some of the structure. The angular distributions from the heavy rare-earth metals are very similar to that from Y and can be understood....... In the spiral phase of Ho, the structure in the c-axis distribution is much reduced, indicating that the Fermi surface is substantially modified by the magnetic ordering, as expected. The photon distribution from the equiatomic Ho-Er alloy is very similar to those from the constituent metals, although...

  12. Sources of variation in innate immunity in great tit nestlings living along a metal pollution gradient: An individual-based approach

    International Nuclear Information System (INIS)

    Vermeulen, Anke; Müller, Wendt; Matson, Kevin D.; Irene Tieleman, B.; Bervoets, Lieven; Eens, Marcel

    2015-01-01

    Excessive deposition of metals in the environment is a well-known example of pollution worldwide. Chronic exposure of organisms to metals can have a detrimental effect on reproduction, behavior, health and survival, due to the negative effects on components of the immune system. However, little is known about the effects of chronic sublethal metal exposure on immunity, especially for wildlife. In our study, we examined the constitutive innate immunity of great tit (Parus major) nestlings (N = 234) living in four populations along a metal pollution gradient. For each nestling, we determined the individual metal concentrations (lead, cadmium, arsenic) present in the red blood cells and measured four different innate immune parameters (agglutination, lysis, haptoglobin concentrations and nitric oxide concentrations) to investigate the relationship between metal exposure and immunological condition. While we found significant differences in endogenous metal concentrations among populations with the highest concentrations closest to the pollution source, we did not observe corresponding patterns in our immune measures. However, when evaluating relationships between metal concentrations and immune parameters at the individual level, we found negative effects of lead and, to a lesser extent, arsenic and cadmium on lysis. In addition, high arsenic concentrations appear to elicit inflammation, as reflected by elevated haptoglobin concentrations. Thus despite the lack of a geographic association between pollution and immunity, this type of association was present at the individual level at a very early life stage. The high variation in metal concentrations and immune measures observed within populations indicates a high level of heterogeneity along an existing pollution gradient. Interestingly, we also found substantial within nest variation, for which the sources remain unclear, and which highlights the need of an individual-based approach. - Highlights: • Innate immunity

  13. Sources of variation in innate immunity in great tit nestlings living along a metal pollution gradient: An individual-based approach

    Energy Technology Data Exchange (ETDEWEB)

    Vermeulen, Anke, E-mail: anke.vermeulen@uantwerpen.be [Department of Biology — Ethology, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium); Müller, Wendt, E-mail: wendt.mueller@uantwerpen.be [Department of Biology — Ethology, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium); Matson, Kevin D., E-mail: k.d.matson@rug.nl [Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, P.O. Box 11103, 9700 CC Groningen (Netherlands); The Resource Ecology Group, Department of Environmental Sciences, Wageningen University, Droevendaalsesteeg 3a, 6708PB Wageningen (Netherlands); Irene Tieleman, B., E-mail: b.i.tieleman@rug.nl [Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, P.O. Box 11103, 9700 CC Groningen (Netherlands); Bervoets, Lieven, E-mail: lieven.bervoets@uantwerpen.be [Department of Biology — SPHERE, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen (Belgium); Eens, Marcel, E-mail: marcel.eens@uantwerpen.be [Department of Biology — Ethology, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium)

    2015-03-01

    Excessive deposition of metals in the environment is a well-known example of pollution worldwide. Chronic exposure of organisms to metals can have a detrimental effect on reproduction, behavior, health and survival, due to the negative effects on components of the immune system. However, little is known about the effects of chronic sublethal metal exposure on immunity, especially for wildlife. In our study, we examined the constitutive innate immunity of great tit (Parus major) nestlings (N = 234) living in four populations along a metal pollution gradient. For each nestling, we determined the individual metal concentrations (lead, cadmium, arsenic) present in the red blood cells and measured four different innate immune parameters (agglutination, lysis, haptoglobin concentrations and nitric oxide concentrations) to investigate the relationship between metal exposure and immunological condition. While we found significant differences in endogenous metal concentrations among populations with the highest concentrations closest to the pollution source, we did not observe corresponding patterns in our immune measures. However, when evaluating relationships between metal concentrations and immune parameters at the individual level, we found negative effects of lead and, to a lesser extent, arsenic and cadmium on lysis. In addition, high arsenic concentrations appear to elicit inflammation, as reflected by elevated haptoglobin concentrations. Thus despite the lack of a geographic association between pollution and immunity, this type of association was present at the individual level at a very early life stage. The high variation in metal concentrations and immune measures observed within populations indicates a high level of heterogeneity along an existing pollution gradient. Interestingly, we also found substantial within nest variation, for which the sources remain unclear, and which highlights the need of an individual-based approach. - Highlights: • Innate immunity

  14. Thermal, spectral, magnetic and biological studies of thiosemicarbazones complexes with metal ions: Cu(II), Co(II), Ni(II), Fe(III), Zn(II), Mn(II) and UO2(VI)

    International Nuclear Information System (INIS)

    Mashaly, M.M.; Seleem, H.S.; El-Behairy, M.A.; Habib, H.A.

    2004-01-01

    Thiosemicarbazones ligands, isatin-3-thiosemicarbazone(HIT) and N-acetylisatin-3-thiosemicarbazone (HAIT), which have tridentate ONN coordinating sites were prepared. The complexes of both ligands with Cu(II), Co(II), Ni(II), Fe(III), Zn(II), Mn(II) and UO 2 (VI) ions were isolated. The ligands and their metal complexes were characterized by elemental analysis, IR, UV-Vis and mass spectra, also by conductance, magnetic moment and TG-DSC measurements. All the transition metal complexes have octahedral configurations, except Cu-complexes which have planar geometry and the UO 2 (VI) complexes which have coordination number 8 and may acquire the distorted dodecahedral geometry. Thermal studies explored the possibility of obtaining new complexes. Inversion from octahedral to square-planar configuration occurred upon heating the parent Ni-HIAT complex to form the corresponding pyrolytic product. The antifungal activity against the tested organisms showed that some metal complexes enhanced the activity with respect to the parent ligands. (author)

  15. Removal of Cu(II) metal ions from aqueous solution by amine functionalized magnetic nanoparticles

    Science.gov (United States)

    Kothavale, V. P.; Karade, V. C.; Waifalkar, P. P.; Sahoo, Subasa C.; Patil, P. S.; Patil, P. B.

    2018-04-01

    The adsorption behavior of Cu(II) metal cations was investigated on the amine functionalized magnetic nanoparticles (MNPs). TheMNPs were synthesized by thesolvothermal method and functionalized with (3-Aminopropyl)triethoxysilane (APTES). MNPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM). The MNPs have pure magnetite phase with particle size around 10-12 nm. MNPs exhibits superparamagnetic behavior with asaturation magnetization of 68 emu/g. The maximum 38 % removal efficiency was obtained for Cu(II) metal ions from the aqueous solution.

  16. Synthesis and structural characterisation of iron(II) and copper(II) diphosphates containing flattened metal oxotetrahedra

    Energy Technology Data Exchange (ETDEWEB)

    Keates, Adam C. [School of Chemistry, University of Southampton, Southampton, Hampshire SO17 1B,. UK (United Kingdom); Wang, Qianlong [Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY (United Kingdom); Weller, Mark T., E-mail: m.t.weller@bath.ac.uk [Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY (United Kingdom)

    2014-02-15

    Single crystal and bulk polycrystalline forms of K{sub 2}MP{sub 2}O{sub 7} (M=Fe(II), Cu(II)) have been synthesised and their structures determined from single crystal X-ray diffraction data. Both compounds crystallize in the tetragonal system, space group P-42{sub 1}m. Their structures are formed from infinite sheets of linked oxopolyhedra of the stoichiometry [MP{sub 2}O{sub 7}]{sup 2−} with potassium cations situated between the layers. The MO{sub 4} tetrahedra share oxygen atoms with [P{sub 2}O{sub 7}]{sup 4−} diphosphate groups and the potassium ions have KO{sub 8} square prismatic geometry. In both compounds the M(II) centre has an unusual strongly flattened, tetrahedral coordination to oxygen, as a result of the Jahn–Teller (JT) effect for the high spin d{sup 6} Fe(II) and p-orbital mixing or a second order JT effect for d{sup 9} Cu(II) centres in four fold coordination. The uncommon transition metal ion environments found in these materials are reflected in their optical absorption spectra and magnetism data. - Graphical abstract: The structures of the tetragonal polymorphs of K{sub 2}MP{sub 2}O{sub 7}, M=Cu(II), Fe(II), consist of infinite sheets of stoichiometry [MP{sub 2}O{sub 7}]{sup 2−}, formed from linked pyrophosphate groups and MO{sub 4} tetrahedra, separated by potassium ions. In both compounds the unusual tetrahedral coordination of the M(II) centre is strongly flattened as a result of Jahn–Teller (JT) effects for high spin, d{sup 6} Fe(II) and p-orbital mixing and second-order JT effects for d{sup 9} Cu(II). Display Omitted - Highlights: • Tetrahedral copper and iron(II) coordinated by oxygen. • New layered phosphate structure. • Jahn–Teller and d{sup 10} distorted coordinations.

  17. Metal-induced stress in bivalves living along a gradient of Cd contamination: relating sub-cellular metal distribution to population-level responses

    International Nuclear Information System (INIS)

    Perceval, Olivier; Couillard, Yves; Pinel-Alloul, Bernadette; Giguere, Anik; Campbell, Peter G.C.

    2004-01-01

    The use of biomarkers to assess the impacts of contaminants on aquatic ecosystems has noticeably increased over the past few years. Few of these studies, however, have contributed to the prediction of ecologically significant effects (i.e., at the population or community levels). The present field study was designed to evaluate the potential of metallothionein (MT) and sub-cellular metal partitioning measurements for predicting toxic effects at higher levels of the biological organization in freshwater bivalves (Pyganodon grandis) chronically exposed to Cd. For that purpose, we quantitatively sampled P. grandis populations in the littoral zone of nine lakes on the Precambrian Canadian Shield during two consecutive summers (1998 and 1999); lakes were characterized by contrasting Cd levels but similar trophic status. We tested relationships between the population status of P. grandis (i.e., growth parameters, density, biomass, secondary production, turnover ratio and cumulative fecundity) and (i) ambient Cd concentrations, (ii) sub-organismal responses (MT concentrations in the gill cytosol of individuals and Cd concentrations in three metal-ligand pools identified as M-HMW, the high molecular weight pool, M-MT, the metallothionein-like pool and M-LMW, the low molecular weight pool) and (iii) ecological confounding factors (food resources, presence of host fishes for the obligatory parasitic larval stage of P. grandis). Our results show that littoral density, live weight, dry viscera biomass, production and cumulative fecundity decreased with increasing concentrations of the free-cadmium ion in the environment (Pearson's r ranging from -0.63 to -0.78). On the other hand, theoretical maximum shell lengths (L ∞ ) in our populations were related to both the dissolved Ca concentration and food quality (sestonic C and N concentrations). Overall, Cd concentrations in the gill cytosolic HMW pool of the individual molluscs were the biomarker response that was most

  18. BIOASSAY STUDIES OF METAL(II) COMPLEXES OF 2,2'-(ETHANE ...

    African Journals Online (AJOL)

    Preferred Customer

    diyldiimino)diacetic acid (EDDA) were prepared and characterized. Coordination complexes of the EDDA ... corresponding amines with alkyl halide to bear diammines of the same class with different substituents. ... Bioassay studies of metal(II) complexes of 2,2'-(ethane-1,2-diyldiimino)diacetic acid. Bull. Chem. Soc. Ethiop.

  19. Physicochemical impact studies of gamma rays on "aspirin" analgesics drug and its metal complexes in solid form: Synthesis, spectroscopic and biological assessment of Ca(II), Mg(II), Sr(II) and Ba(II) aspirinate complexes

    Science.gov (United States)

    Refat, Moamen S.; Sharshar, T.; Elsabawy, Khaled M.; Heiba, Zein K.

    2013-09-01

    Metal aspirinate complexes, M2(Asp)4, where M is Mg(II), Ca(II), Sr(II) or Ba(II) are formed by refluxed of aspirin (Asp) with divalent non-transition metal ions of group (II) and characterized by elemental analysis and spectroscopic measurements (infrared, electronic, 1H NMR, Raman, X-ray powder diffraction and scanning electron microscopy). Elemental analysis of the chelates suggests the stoichiometry is 1:2 (metal:ligand). Infrared spectra of the complexes agree with the coordination to the central metal atom through three donation sites of two oxygen atoms of bridge bidentate carboxylate group and oxygen atom of sbnd Cdbnd O of acetyl group. Infrared spectra coupled with the results of elemental analyzes suggested a distorted octahedral structure for the M(II) aspirinate complexes. Gamma irradiation was tested as a method for stabilization of aspirin as well as their complexes. The effect of gamma irradiation, with dose of 80 Gy, on the properties of aspirinate complexes was studied. The aspirinate chelates have been screened for their in vitro antibacterial activity against four bacteria, gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two strains of fungus (Aspergillus flavus and Candida albicans). The metal chelates were shown to possess more antibacterial activity than the free aspirin chelate.

  20. KINETIC AND EQUILIBRIUM STUDY FOR THE SORPTION OF Pb(II ...

    African Journals Online (AJOL)

    Preferred Customer

    passive process for adsorption of the metal ions by metabolically inactive biomass. ..... split in the concentration gradient between solute concentration in the .... binding capacity of Cd(II), Cr(III), Cu(II), Ni(II), Pb(II) and Sn(II) ions increased with ...

  1. The evolution of stellar metallicity gradients of the Milky Way disk from LSS-GAC main sequence turn-off stars: a two-phase disk formation history?

    International Nuclear Information System (INIS)

    Xiang, Mao-Sheng; Liu, Xiao-Wei; Huang, Yang; Wang, Chun; Ren, Juan-Juan; Chen, Bing-Qiu; Sun, Ning-Chen; Zhang, Hua-Wei; Yuan, Hai-Bo; Rebassa-Mansergas, Alberto; Huo, Zhi-Ying

    2015-01-01

    Accurate measurements of stellar metallicity gradients in the radial and vertical directions of the disk and their temporal variations provide important constraints on the formation and evolution of the Milky Way disk. We use 297 042 main sequence turn-off stars selected from the LAMOST Spectroscopic Survey of the Galactic Anti-center (LSS-GAC) to determine the radial and vertical gradients of stellar metallicity, Δ[Fe/H]/ΔR and Δ[Fe/H]/Δ|Z| of the Milky Way disk in the direction of the anticenter. We determine ages of those turn-off stars by isochrone fitting and measure the temporal variations of metallicity gradients. We have carried out a detailed analysis of the selection effects resulting from the selection, observation and data reduction of LSS-GAC targets and the potential biases of a magnitude limited sample on the determinations of metallicity gradients. Our results show that the gradients, both in the radial and vertical directions, exhibit significant spatial and temporal variations. The radial gradients yielded by stars with the oldest ages (≳ 11 Gyr) are essentially zero at all heights from the disk midplane, while those given by younger stars are always negative. The vertical gradients deduced from stars with the oldest ages (≳ 11 Gyr) are negative and only show very weak variations with Galactocentric distance in the disk plane, R, while those yielded by younger stars show strong variations with R. After being essentially flat at the earliest epochs of disk formation, the radial gradients steepen as age decreases, reaching a maximum (steepest) at age 7–8 Gyr, and then they flatten again. Similar temporal trends are also found for the vertical gradients. We infer that the assembly of the Milky Way disk may have experienced at least two distinct phases. The earlier phase is probably related to a slow, pressure-supported collapse of gas, when the gas settles down to the disk mainly in the vertical direction. In the later phase, there are

  2. OLD MAIN-SEQUENCE TURNOFF PHOTOMETRY IN THE SMALL MAGELLANIC CLOUD. II. STAR FORMATION HISTORY AND ITS SPATIAL GRADIENTS

    International Nuclear Information System (INIS)

    Noel, Noelia E. D.; Gallart, Carme; Hidalgo, Sebastian L.; Aparicio, Antonio; Costa, Edgardo; Mendez, Rene A.

    2009-01-01

    (t) in our fields of the wing area. This is not an exceptional increment as compared with the average ψ(t) but is very significant in the sense that these eastern fields are the only ones of this study in which star formation is currently going on. There is also a strong dichotomy between east/southeast and west in the current irregular shape of the SMC. We find that this dichotomy is produced by the youngest population and began ∼1.0 Gyr ago or later. The age of the old population is similar at all radii and at all azimuth, and we constrain the age of this oldest population to be more than ∼12 Gyr. We do not find yet a region dominated by a true, old, Milky-Way-like, halo at 4.5 kpc from the SMC center, indicating either that this old stellar halo does not exist in the SMC or that its contribution to the stellar populations, at the galactocentric distances of our outermost field, is negligible. Finally, we derive the age-metallicity relation and find that, in all fields, the metallicity increased continuously from early epochs until the present. This is in good agreement with the results from the Ca II triplet, a completely independent method, constituting an external consistency proof of IAC-pop in determining the chemical enrichment law.

  3. Mixed ligand complexes of alkaline earth metals: Part XII. Mg(II, Ca(II, Sr(II and Ba(II complexes with 5-chlorosalicylaldehyde and salicylaldehyde or hydroxyaromatic ketones

    Directory of Open Access Journals (Sweden)

    MITHLESH AGRAWAL

    2002-04-01

    Full Text Available The reactions of alkaline earth metal chlorides with 5-chlorosalicylaldehyde and salicylaldehyde, 2-hydroxyacetophenone or 2-hydroxypropiophenone have been carried out in 1 : 1 : 1 mole ratio and the mixed ligand complexes of the type MLL’(H2O2 (where M = Mg(II, Ca(II, Sr(II and Ba(II, HL = 5-chlorosalicylaldehyde and HL’ = salicylaldehyde, 2-hydroxyacetophenone or 2-hydroxypropiophenone have been isolated. These complexes were characterized by TLC, conductance measurements, IR and 1H-NMR spectra.

  4. Metal waste forms from treatment of EBR-II spent fuel

    International Nuclear Information System (INIS)

    Abraham, D. P.

    1998-01-01

    Demonstration of Argonne National Laboratory's electrometallurgical treatment of spent nuclear fuel is currently being conducted on irradiated, metallic driver fuel and blanket fuel elements from the Experimental Breeder Reactor-II (EBR-II) in Idaho. The residual metallic material from the electrometallurgical treatment process is consolidated into an ingot, the metal waste form (MWF), by employing an induction furnace in a hot cell. Scanning electron microscopy (SEM) and chemical analyses have been performed on irradiated cladding hulls from the driver fuel, and on samples from the alloy ingots. This paper presents the microstructures of the radioactive ingots and compares them with observations on simulated waste forms prepared using non-irradiated material. These simulated waste forms have the baseline composition of stainless steel - 15 wt % zirconium (SS-15Zr). Additions of noble metal elements, which serve as surrogates for fission products, and actinides are made to that baseline composition. The partitioning of noble metal and actinide elements into alloy phases and the role of zirconium for incorporating these elements is discussed in this paper

  5. Liquid metal blanket module testing and design for ITER/TIBER II

    International Nuclear Information System (INIS)

    Mattas, R.F.; Cha, Y.; Finn, P.A.; Majumdar, S.; Picologlou, B.; Stevens, H.; Turner, L.

    1988-05-01

    A major goal for ITER is the testing of nuclear components to demonstrate the integrated performance of the most attractive concepts that can lead to a commercial fusion reactor. As part of the ITER/TIBER II study, the test program and design of test models were examined for a number of blanket concepts. The work at Argonne National Laboratory focused on self-cooled liquid metal blankets. A test program for liquid metal blankets was developed based upon the ITER/TIBER II operating schedule and the specific data needs to resolve the key issues for liquid metals. Testing can begin early in reactor operation with liquid metal MHD tests to confirm predictive capability. Combined heat transfer/MHD tests can be performed during initial plasma operation. After acceptable heat transfer performance is verified, tests to determine the integrated high temperature performance in a neutron environment can begin. During the high availability phase operation, long term performance and reliability tests will be performed. It is envisioned that a companion test program will be conducted outside ITER to determine behavior under severe accident conditions and upper performance limits. A detailed design of a liquid metal test module and auxiliary equipment was also developed. The module followed the design of the TPSS blanket. Detailed analysis of the heat transfer and tritium systems were performed, and the overall layout of the systems was determined. In general, the blanket module appears to be capable of addressing most of the testing needs. 8 refs., 27 figs., 11 tabs

  6. Solvent effects in time-dependent self-consistent field methods. II. Variational formulations and analytical gradients

    International Nuclear Information System (INIS)

    Bjorgaard, J. A.; Velizhanin, K. A.; Tretiak, S.

    2015-01-01

    This study describes variational energy expressions and analytical excited state energy gradients for time-dependent self-consistent field methods with polarizable solvent effects. Linear response, vertical excitation, and state-specific solventmodels are examined. Enforcing a variational ground stateenergy expression in the state-specific model is found to reduce it to the vertical excitation model. Variational excited state energy expressions are then provided for the linear response and vertical excitation models and analytical gradients are formulated. Using semiempiricalmodel chemistry, the variational expressions are verified by numerical and analytical differentiation with respect to a static external electric field. Lastly, analytical gradients are further tested by performing microcanonical excited state molecular dynamics with p-nitroaniline

  7. Metal-ion exchange induced structural transformation as a way of forming novel Ni(II)− and Cu(II)−salicylaldimine structures

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jing-Yun, E-mail: jyunwu@ncnu.edu.tw; Tsai, Chi-Jou; Chang, Ching-Yun; Wu, Yung-Yuan

    2017-02-15

    A Zn(II)−salicylaldimine complex [Zn(L{sup salpyca})(H{sub 2}O)]{sub n} (1, where H{sub 2}L{sup salpyca}=4-hydroxy-3-(((pyridin-2-yl)methylimino)methyl)benzoic acid), with a one-dimensional (1D) chain structure, has been successfully converted to a discrete Ni(II)−salicylaldimine complex [Ni(L{sup salpyca})(H{sub 2}O){sub 3}] (2) and an infinite Cu(II)−salicylaldimine complex ([Cu(L{sup salpyca})]·3H{sub 2}O){sub n} (3) through a metal-ion exchange induced structural transformation process. However, such processes do not worked by Mn(II) and Co(II) ions. Solid-state structure analyses reveal that complexes 1–3 form comparable coordinative or supramolecular zigzag chains running along the crystallographic [201] direction. In addition, replacing Zn(II) ion by Ni(II) and Cu(II) ions caused changes in coordination environment and sphere of metal centers, from a 5-coordinate intermediate geometry of square pyramidal and trigonal bipyramidal in 1 to a 6-coordinate octahedral geometry in 2, and to a 4-coordiante square planar geometry in 3. This study shows that metal-ion exchange serves as a very efficient way of forming new coordination complexes that may not be obtained through direct synthesis. - Graphical abstract: A Zn(II)−salicylaldimine zigzag chain has been successfully converted to a Ni(II)−salicylaldimine supramolecular zigzag chain and a Cu(II)−salicylaldimine coordinative zigzag chain through metal-ion exchange induced structural transformations, which is not achieved by Mn(II) and Co(II) ions.

  8. Influence of a pressure gradient distal to implanted bare-metal stent on in-stent restenosis after percutaneous coronary intervention

    DEFF Research Database (Denmark)

    Jensen, Lisette Okkels; Thayssen, Per; Thuesen, Leif

    2007-01-01

    pullback recording in the entire length of the artery. METHODS AND RESULTS: In 98 patients with angina pectoris, 1 de novo coronary lesion was treated with a bare-metal stent. After stent implantation, pressure wire measurements (P(d)=mean hyperemic coronary pressure and P(a)=mean aortic pressure) were......-stent restenosis after 9 months. CONCLUSIONS: A residual abnormal P(d)/P(a) distal to a bare-metal stent was an independent predictor of in-stent restenosis after implantation of a coronary bare-metal stent. Udgivelsesdato: 2007-Dec-11......BACKGROUND: Fractional flow reserve predicts cardiac events after coronary stent implantation. The aim of the present study was to assess the 9-month angiographic in-stent restenosis rate in the setting of optimal stenting and a persisting gradient distal to the stent as assessed by a pressure wire...

  9. Ca II triplet spectroscopy of RGB stars in NGC 6822: kinematics and metallicities

    Science.gov (United States)

    Swan, J.; Cole, A. A.; Tolstoy, E.; Irwin, M. J.

    2016-03-01

    We present a detailed analysis of the chemistry and kinematics of red giants in the dwarf irregular galaxy NGC 6822. Spectroscopy at ≈8500 Å was acquired for 72 red giant stars across two fields using FORS2 at the VLT. Line-of-sight extinction was individually estimated for each target star to accommodate the variable reddening across NGC 6822. The mean radial velocity was found to be = -52.8 ± 2.2 km s-1 with dispersion σv = 24.1 km s-1, in agreement with other studies. Ca II triplet equivalent widths were converted into [Fe/H] metallicities using a V magnitude proxy for surface gravity. The average metallicity was = -0.84 ± 0.04 with dispersion σ = 0.31 dex and interquartile range 0.48. Our assignment of individual reddening values makes our analysis more sensitive to spatial variations in metallicity than previous studies. We divide our sample into metal-rich and metal-poor stars; the former were found to cluster towards small radii with the metal-poor stars more evenly distributed across the galaxy. The velocity dispersion of the metal-poor stars was found to be higher than that of the metal-rich stars (σ _{v_MP}=27.4 km s-1; σ _{v_MR}=21.1 km s-1); combined with the age-metallicity relation this indicates that the older populations have either been dynamically heated during their lifetimes or were born in a less disc-like distribution than the younger stars.. The low ratio vrot/σv suggests that within the inner 10 arcmin, NGC 6822's stars are dynamically decoupled from the H I gas, and possibly distributed in a thick disc or spheroid structure.

  10. Metallicities for old stellar systems from Ca II triplet strengths in member giants

    International Nuclear Information System (INIS)

    Armandroff, T.E.; Da costa, G.S.

    1991-01-01

    The spectra of giants in six well-studied Galactic globulars spanning a wide range of abundance are used to investigate the utility of the Ca II triplet as an abundance indicator. The calibration resulting from these clusters is used to derive metal abundances from the spectra of giants in Eridanus, Pal 12, and the Carina dwarf spheroidal galaxy. The results obtained are compared with earlier determinations based on giant branch photometry. 37 refs

  11. The synthesis and properties of some organometallic compounds containing group IV (Ge, Sn)-group II (Zn, Cd) metal---metal bonds

    NARCIS (Netherlands)

    Des Tombe, F.J.A.; Kerk, G.J.M. van der; Creemers, H.M.J.C.; Carey, N.A.D.; Noltes, J.G.

    1972-01-01

    The reactions of triphenylgermane and triphenyltin hydride with coordinatively saturated organozinc or organocadmium compounds give organometallic complexes containing Group IV (Ge, Sn)-Group II(Zn, Cd) metal---metal bonds. The 2,2′-bipyridine complexes show solvent-dependent charge-transfer

  12. The role of metals in production and scavenging of reactive oxygen species in photosystem II.

    Science.gov (United States)

    Pospíšil, Pavel

    2014-07-01

    Metal ions play a crucial role in enzymatic reactions in all photosynthetic organisms such as cyanobacteria, algae and plants. It well known that metal ions maintain the binding of substrate in the active site of the metalloenzymes and control the redox activity of the metalloenzyme in the enzymatic reaction. A large pigment-protein complex, PSII, known to serve as a water-plastoquinone oxidoreductase, contains three metal centers comprising non-heme iron, heme iron of Cyt b559 and the water-splitting manganese complex. Metal ions bound to PSII proteins maintain the electron transport from water to plastoquinone and regulate the pro-oxidant and antioxidant activity in PSII. In this review, attention is focused on the role of PSII metal centers in (i) the formation of superoxide anion and hydroxyl radicals by sequential one-electron reduction of molecular oxygen and the formation of hydrogen peroxide by incomplete two-electron oxidation of water; and (ii) the elimination of superoxide anion radical by one-electron oxidation and reduction (superoxide dismutase activity) and of hydrogen peroxide by two-electron oxidation and reduction (catalase activity). The balance between the formation and elimination of reactive oxygen species by PSII metal centers is discussed as an important aspect in the prevention of photo-oxidative damage of PSII proteins and lipids. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  13. Programmed gradient descent biosorption of strontium ions by Saccaromyces cerevisiae and ashing analysis: A decrement solution for nuclide and heavy metal disposal

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Mingxue [Life Science and Engineering College, Southwest University of Science and Technology, Mianyang, 621010 (China); Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education of China, Mianyang, 621010 (China); Dong, Faqin, E-mail: fqdong@swust.edu.cn [Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education of China, Mianyang, 621010 (China); Zhang, Wei [Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education of China, Mianyang, 621010 (China); Nie, Xiaoqin [Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory, Mianyang, 621010 (China); Sun, Shiyong [Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education of China, Mianyang, 621010 (China); Wei, Hongfu; Luo, Lang; Xiang, Sha; Zhang, Gege [Life Science and Engineering College, Southwest University of Science and Technology, Mianyang, 621010 (China)

    2016-08-15

    Highlights: • A programmed gradient descent biosorption process was designed. • The adsorption and bioaccumulation quantity of strontium ions by yeast cell were measured. • The decrement of biosorbents after biosorption by ashing was analyzed. • A technological flow process of decrement solution for waste disposal was proposed. - Abstract: One of the waste disposal principles is decrement. The programmed gradient descent biosorption of strontium ions by Saccaromyces cerevisiae regarding bioremoval and ashing process for decrement were studied in present research. The results indicated that S. cerevisiae cells showed valid biosorption for strontium ions with greater than 90% bioremoval efficiency for high concentration strontium ions under batch culture conditions. The S. cerevisiae cells bioaccumulated approximately 10% of strontium ions in the cytoplasm besides adsorbing 90% strontium ions on cell wall. The programmed gradient descent biosorption presented good performance with a nearly 100% bioremoval ratio for low concentration strontium ions after 3 cycles. The ashing process resulted in a huge volume and weight reduction ratio as well as enrichment for strontium in the ash. XRD results showed that SrSO{sub 4} existed in ash. Simulated experiments proved that sulfate could adjust the precipitation of strontium ions. Finally, we proposed a technological flow process that combined the programmed gradient descent biosorption and ashing, which could yield great decrement and allow the supernatant to meet discharge standard. This technological flow process may be beneficial for nuclides and heavy metal disposal treatment in many fields.

  14. Modelling the extra and intracellular uptake and discharge of heavy metals in Fontinalis antipyretica transplanted along a heavy metal and pH contamination gradient

    International Nuclear Information System (INIS)

    Fernandez, J.A.; Vazquez, M.D.; Lopez, J.; Carballeira, A.

    2006-01-01

    Samples of the aquatic bryophyte Fontinalis antipyretica Hedw. were transplanted to different sites with the aim of characterizing the kinetics of the uptake and discharge of heavy metals in the extra and intracellular compartments. The accumulation of metals in extracellular compartments, characterized by an initial rapid accumulation, then a gradual slowing down over time, fitted perfectly to a Michaelis-Menten model. The discharge of metals from the same compartment followed an inverse linear model or an inverse Michaelis-Menten model, depending on the metal. In intracellular sites both uptake and discharge occurred more slowly and progressively, following a linear model. We also observed that the acidity of the environment greatly affected metal accumulation in extracellular sites, even when the metals were present at relatively high concentrations, whereas the uptake of metals within cells was much less affected by pH. - The kinetics of uptake and discharge of heavy metals, in different cellular locations, were studied in transplanted aquatic mosses

  15. Removal of industrial dyes and heavy metals by Beauveria bassiana: FTIR, SEM, TEM and AFM investigations with Pb(II).

    Science.gov (United States)

    Gola, Deepak; Malik, Anushree; Namburath, Maneesh; Ahammad, Shaikh Ziauddin

    2017-10-01

    Presence of industrial dyes and heavy metal as a contaminant in environment poses a great risk to human health. In order to develop a potential technology for remediation of dyes (Reactive remazol red, Yellow 3RS, Indanthrene blue and Vat novatic grey) and heavy metal [Cu(II), Ni(II), Cd(II), Zn(II), Cr(VI) and Pb(II)] contamination, present study was performed with entomopathogenic fungi, Beauveria bassiana (MTCC no. 4580). High dye removal (88-97%) was observed during the growth of B. bassiana while removal percentage for heavy metals ranged from 58 to 75%. Further, detailed investigations were performed with Pb(II) in terms of growth kinetics, effect of process parameters and mechanism of removal. Growth rate decreased from 0.118 h -1 (control) to 0.031 h -1 , showing 28% reduction in biomass at 30 mg L -1 Pb(II) with 58.4% metal removal. Maximum Pb(II) removal was observed at 30 °C, neutral pH and 30 mg L -1 initial metal concentration. FTIR analysis indicated the changes induced by Pb(II) in functional groups on biomass surface. Further, microscopic analysis (SEM and atomic force microscopy (AFM)) was performed to understand the changes in cell surface morphology of the fungal cell. SEM micrograph showed a clear deformation of fungal hyphae, whereas AFM studies proved the increase in surface roughness (RSM) in comparison to control cell. Homogenous bioaccumulation of Pb(II) inside the fungal cell was clearly depicted by TEM-high-angle annular dark field coupled with EDX. Present study provides an insight into the mechanism of Pb(II) bioremediation and strengthens the significance of using entomopathogenic fungus such as B. bassiana for metal and dye removal.

  16. Magnetophoretic velocimetry of manganese(II) in a single microdroplet in a flow system under a high gradient magnetic field generated with a superconducting magnet.

    Science.gov (United States)

    Suwa, Masayori; Watarai, Hitoshi

    2002-10-01

    An experimental system for magnetophoretic velocimetry, which could determine the volume magnetic susceptibility of a single particle dispersed in a liquid phase from a magnetophoretic velocity, has been developed. A micrometer-sized high-gradient magnetic field could be generated in a capillary by a pair of iron pole pieces in a superconducting magnet (10 T). The magnetophoretic behavior of a single particle in a capillary flow system was investigated under the inhomogeneous magnetic field. From the magnetophoretic velocity of a polystyrene latex particle dispersed in a MnCl2 aqueous solution, the product of the magnetic flux density and the gradient, B(dB/dx), was determined as a function of the position along the capillary. The maximum value of B(dB/dx) was 4.7 x 10(4) T2 m(-1), which was approximately 100 times higher than that obtained by two Nd-Fe-B permanent magnets (0.4 T). Organic droplets extracting manganese(II) with 2-thenoyltrifluoroacetone and tri-n-octylphosphine oxide from MnCl2 solution were used as test samples. The difference of the volume magnetic susceptibility between the droplet and the medium could be determined from the magnetophoretic velocity. This method allowed us to continuously measure a volume magnetic susceptibility of 10-6 level for a picoliter droplet and to determine manganese(II) in the single droplet at the attomole level.

  17. Multi-Scale Modification of Metallic Implants With Pore Gradients, Polyelectrolytes and Their Indirect Monitoring In vivo

    OpenAIRE

    Vrana, Nihal E.; Dupret-Bories, Agnes; Chaubaroux, Christophe; Rieger, Elisabeth; Debry, Christian; Vautier, Dominique; Metz-Boutigue, Marie-Helene; Lavalle, Philippe

    2013-01-01

    Metallic implants, especially titanium implants, are widely used in clinical applications. Tissue in-growth and integration to these implants in the tissues are important parameters for successful clinical outcomes. In order to improve tissue integration, porous metallic implants have being developed. Open porosity of metallic foams is very advantageous, since the pore areas can be functionalized without compromising the mechanical properties of the whole structure. Here we describe such modi...

  18. Immobilization of radionuclides and heavy metals through anaerobic bio-oxidation of Fe(II)

    International Nuclear Information System (INIS)

    Lack, J.G.; Chaudhuri, S.K.; Kelly, S.D.; Kemner, K.M.; O'Connor, S.M.; Coates, J.D.

    2002-01-01

    Adsorption of heavy metals and radionuclides (HMR) onto iron and manganese oxides has long been recognized as an important reaction for the immobilization of these compounds. However, in environments containing elevated concentrations of these HMR the adsorptive capacity of the iron and manganese oxides may well be exceeded, and the HMR can migrate as soluble compounds in aqueous systems. Here we demonstrate the potential of a bioremediative strategy for HMR stabilization in reducing environments based on the recently described anaerobic nitrate-dependent Fe(II) oxidation by Dechlorosoma species. Bio-oxidation of 10 mM Fe(II) and precipitation of Fe(III) oxides by these organisms resulted in rapid adsorption and removal of 55 μM uranium and 81 μM cobalt from solution. The adsorptive capacity of the biogenic Fe(III) oxides was lower than that of abiotically produced Fe(III) oxides (100 μM for both metals), which may have been a result of steric hindrance by the microbial cells on the iron oxide surfaces. The binding capacity of the biogenic oxides for different heavy metals was indirectly correlated to the atomic radius of the bound element. X-ray absorption spectroscopy indicated that the uranium was bound to the biogenically produced Fe(III) oxides as U(VI) and that the U(VI) formed bidentate and tridentate inner-sphere complexes with the Fe(III) oxide surfaces. Dechlorosoma suillum oxidation was specific for Fe(II), and the organism did not enzymatically oxidize U(IV) or Co(II). Small amounts (less than 2.5 μM) of Cr(III) were reoxidized by D. suillum; however, this appeared to be inversely dependent on the initial concentration of the Cr(III). The results of this study demonstrate the potential of this novel approach for stabilization and immobilization of HMR in the environment.

  19. Wireless electrochemical preparation of gradient nanoclusters consisting of copper(II), stearic acid and montmorillonite on a copper wire for headspace in-tube microextraction of chlorobenzenes.

    Science.gov (United States)

    Enteshari Najafabadi, Marzieh; Bagheri, Habib

    2017-12-26

    This work introduces a new gradient fiber coating for microextraction of chlorobenzenes. Nanoclusters of organoclay-Cu(II) on a copper wire were fabricated by wireless electrofunctionalization. The resultant gradient coatings are more robust, and thermally and mechanically stable. Wireless electrofunctionalization was carried out in a bipolar cell under a constant deposition potential and using an ethanolic electrolyte solution containing stearic acid and montmorillonite. Stearic acid acts as an inexpensive and green coating while montmorillonite acts as a modifier to impart thermal stability. The gradient morphology of the nanoclusters was investigated by scanning electron microscopy, thermogravimetric analysis and energy dispersive X-ray spectroscopy. The coated wire was placed in a hollow needle and used for headspace in-tube microextraction (HS-ITME) of chlorobenzenes (CBs). Effects of various parameters affecting synthesis and extraction were optimized. Following extraction, the needles were directly inserted into the GC injector, and the CBs (chlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3,4-tetrachlorobenzene) were quantified by GC-MS. The limits of detection under optimized conditions range from 0.5 to 10 ng.L -1 . The intra- and inter-day relative standard deviations (RSDs) (for n = 10, 5 respectively) using a single fiber are 6-10 and 10-15%, respectively. The fiber-to-fiber RSDs (for n = 3) is between 17 and 24%. The method was successfully applied to the extraction of CBs from real water samples, and relative recoveries are between 91 and 110%. Graphical abstract A gradient coating of organoclay-Cu nanoclusters was fabricated on a copper wire by wireless electrofunctionalization. The oxidation of copper takes place at the anodic pole (red) while dissolved oxygen in ethanol solution is reduced at the cathodic pole (blue).

  20. Calculation of interfacial tensions with gradient theory. I. Pure and Pseudo-Pure Fluids. II. Binary Systems

    DEFF Research Database (Denmark)

    Zuo, You-Xiang; Stenby, Erling Halfdan

    1997-01-01

    .26% at low pressure, and that of naphtha reformate cuts was 3.6%. In addition, the gradient theory was used to predict interfacial tensions for binary systems in the near-critical region. The results show excellent agreement between the predicted and experimental IFTs at high and moderate levels, while....... A consistent procedure for the estimation of properties associated to lumped systems. Fluid Phase Equilibria, 87: 89-197] was used to lump a mixture into one pseudocomponent, and its IFTs were calculated by means of the method of pure fluids. On the basis of the SRK EOS, the overall AAD of mixtures was 3...

  1. Study of surface modifications for improved selected metal (II-VI) semiconductor based devices

    Science.gov (United States)

    Blomfield, Christopher James

    Metal-semiconductor contacts are of fundamental importance to the operation of all semiconductor devices. There are many competing theories of Schottky barrier formation but as yet no quantitative predictive model exists to adequately explain metal-semiconductor interfaces. The II-VI compound semiconductors CdTe, CdS and ZnSe have recently come to the fore with the advent of high efficiency photovoltaic cells and short wavelength light emitters. Major problems still exist however in forming metal contacts to these materials with the desired properties. This work presents results which make a significant contribution to the theory of metal/II-VI interface behaviour in terms of Schottky barriers to n-type CdTe, CdS and ZnSe.Predominantly aqueous based wet chemical etchants were applied to the surfaces of CdTe, CdS and ZnSe which were subsequently characterised by X-ray photoelectron spectroscopy. The ionic nature of these II-VI compounds meant that they behaved as insoluble salts of strong bases and weak acids. Acid etchants induced a stoichiometric excess of semiconductor anion at the surface which appeared to be predominantly in the elemental or hydrogenated state. Alkaline etchants conversely induced a stoichiometric excess of semiconductor cation at the surface which appeared to be in an oxidised state.Metal contacts were vacuum-evaporated onto these etched surfaces and characterised by current-voltage and capacitance-voltage techniques. The surface preparation was found to have a clear influence upon the electrical properties of Schottky barriers formed to etched surfaces. Reducing the native surface oxide produced near ideal Schottky diodes. An extended study of Au, Ag and Sb contacts to [mathematical formula] substrates again revealed the formation of several discrete Schottky barriers largely independent of the metal used; for [mathematical formula]. Deep levels measured within this study and those reported in the literature led to the conclusion that Fermi

  2. Extraction behaviour of 2-octylaminopyridine towards lead(II) from succinate media and its separation from other toxic metals

    International Nuclear Information System (INIS)

    Mane, Chandrashekhar P.; Anuse, Mansing A.

    2008-01-01

    Liquid-liquid extraction of lead(II) from succinate media was carried out with 2-octylaminopyridine (2-OAP) in chloroform. Lead(II) was quantitatively extracted with 0.036 M 2-OAP in chloroform from 0.005-0.007 M sodium succinate when equilibrated for 5 min. Lead(II) from the organic phase was stripped with three 10 mL portions of 0.4 M acetic acid and determined titrimetrically with EDTA. The nature of extracted species was determined from the log-log plot. The optimum conditions have been evaluated based on a critical study of weak acid concentration, extractant concentration, period of equilibration and effect of diluents. The metal loading capacity of the reagent was found to be 8 mg of lead(II) with 10 mL 0.036 M of the extractant. The extraction of the lead(II) was carried out in presence of various ions to ascertain the tolerance limit of individual. Temperature dependence of the extraction equilibrium constants was examined to estimate the apparent thermodynamic functions (ΔH, ΔS and ΔG) for extraction reaction. Lead(II) was successfully separated from commonly associated metal ions such as Bi(III), Hg(II), Cr(VI), Cd(II), Zn(II), Al(III), Ca(II), Ba(II) and from binary and ternary mixtures. The method was extended for determination of lead(II) in real samples

  3. Structure of the Ni(II) complex of Escherichia coli peptide deformylase and suggestions on deformylase activities depending on different metal(II) centres.

    Science.gov (United States)

    Yen, Ngo Thi Hai; Bogdanović, Xenia; Palm, Gottfried J; Kühl, Olaf; Hinrichs, Winfried

    2010-02-01

    Crystal structures of polypeptide deformylase (PDF) of Escherichia coli with nickel(II) replacing the native iron(II) have been solved with chloride and formate as metal ligands. The chloro complex is a model for the correct protonation state of the hydrolytic hydroxo ligand and the protonated status of the Glu133 side chain as part of the hydrolytic mechanism. The ambiguity that recently some PDFs have been identified with Zn(2+) ion as the active-site centre whereas others are only active with Fe(2+) (or Co(2+), Ni(2+) is discussed with respect to Lewis acid criteria of the metal ion and substrate activation by the CD loop.

  4. Temperature Gradient Effect on Gas Discrimination Power of a Metal-Oxide Thin-Film Sensor Microarray

    Directory of Open Access Journals (Sweden)

    Joachim Goschnick

    2004-05-01

    Full Text Available Abstract: The paper presents results concerning the effect of spatial inhomogeneous operating temperature on the gas discrimination power of a gas-sensor microarray, with the latter based on a thin SnO2 film employed in the KAMINA electronic nose. Three different temperature distributions over the substrate are discussed: a nearly homogeneous one and two temperature gradients, equal to approx. 3.3 oC/mm and 6.7 oC/mm, applied across the sensor elements (segments of the array. The gas discrimination power of the microarray is judged by using the Mahalanobis distance in the LDA (Linear Discrimination Analysis coordinate system between the data clusters obtained by the response of the microarray to four target vapors: ethanol, acetone, propanol and ammonia. It is shown that the application of a temperature gradient increases the gas discrimination power of the microarray by up to 35 %.

  5. Indolenine meso-substituted dibenzotetraaza[14]annulene and its coordination chemistry toward the transition metal ions Mn(III), Fe(III), Co(II), Ni(II), Cu(II), and Pd(II).

    Science.gov (United States)

    Khaledi, Hamid; Olmstead, Marilyn M; Ali, Hapipah Mohd; Thomas, Noel F

    2013-02-18

    A new dibenzotetraaza[14]annulene bearing two 3,3-dimethylindolenine fragments at the meso positions (LH(2)), has been synthesized through a nontemplate method. X-ray crystallography shows that the whole molecule is planar. The basicity of the indolenine ring permits the macrocycle to be protonated external to the core and form LH(4)(2+)·2Cl(-). Yet another structural modification having strong C-H···π interactions was found in the chloroform solvate of LH(2). The latter two modifications are accompanied by a degree of nonplanar distortion. The antiaromatic core of the macrocycle can accommodate a number of metal ions, Mn(III), Fe(III), Co(II), Ni(II) and Cu(II), to form complexes of [Mn(L)Br], [Mn(L)Cl], [Fe(LH(2))Cl(2)](+)·Cl(-), [Co(L)], [Ni(L)], and [Cu(L)]. In addition, the reaction of LH(2) with the larger Pd(II) ion leads to the formation of [Pd(2)(LH(2))(2)(OAc)(4)] wherein the macrocycle acts as a semiflexible ditopic ligand to coordinate pairs of metal ions via its indolenine N atoms into dinuclear metallocycles. The compounds LH(2), [Co(L)], and [Ni(L)] are isostructural and feature close π-stacking as well as linear chain arrangements in the case of the metal complexes. Variable temperature magnetic susceptibility measurements showed thermally induced paramagnetism in [Ni(L)].

  6. Metals from the ritual site of Shaitanskoye Ozero II (Sverdlovsk Oblast, Russia

    Directory of Open Access Journals (Sweden)

    Nikolaevna Korochkova, Olga

    2010-12-01

    Full Text Available The present article describes materials from the ritual site of Shaitanskoye Ozero II, Sverdlovsk Oblast. Few excavations carried out at the site measuring less than 240 sq. m in size, yielded more than 160 bronze artifacts: utensils, weapons, rolled copper ornaments, and abundant smelting and casting waste. Apart from Seima-Turbino (celts and laminar knives and Eurasian types (daggers with cast hilts, truncated knives with guards, fluted bracelets and rings, several metal artifacts were revealed manufactured in the style of the Samus-Kizhirovo tradition. Bronze artifacts, stone knives and scrapers, and numerous arrowheads are accompanied by ceramics of the Koptyaki type. Metals use mainly a copper-tin alloy. This assemblage is shown to be relevant to the local tradition of metalworking, which, in this particular region, was comparatively ancient having been left uninterrupted by the rapid migrations of the Seima-Turbino people. In addition, the assemblage indicates the sources from which post-Seima artifacts reached the Alakul people. These artifacts may also have been linked with a large metalworking center located in the Middle Urals.

    Este artículo describe los materiales del sitio ritual de Shaitanskoye Ozero II, Provincia de Sverdlovsk. Las reducidas excavaciones emprendidas en el lugar con superficie inferior a los 240 m2 han entregado más de 160 objetos de bronce: utensilios, armas, adornos en espiral de cobre y abundantes residuos de la fusión y el trabajo del metal. Además de tipos Seima-Turbino (hachas tubulares y cuchillos planos y Euroasiáticos (puñales de mango fundido, cuchillos con empuñadura de lengüeta, brazaletes y anillos acanalados, varios artefactos metálicos resultaron manufacturados según el estilo de la tradición Samus-Kizhirovo. Los artefactos de bronce, los líticos (cuchillos, raspadores y numerosas puntas de flecha están acompañados por cerámicos de tipo Koptyaki. El metal es

  7. Heavy metal concentrations in a soil-plant-snail food chain along a terrestrial soil pollution gradient

    Energy Technology Data Exchange (ETDEWEB)

    Notten, M.J.M. [Institute of Ecological Science, Department of Systems Ecology, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam (Netherlands)]. E-mail: martje.notten@ecology.falw.vu.nl; Oosthoek, A.J.P. [Institute of Ecological Science, Department of Systems Ecology, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam (Netherlands); Rozema, J. [Institute of Ecological Science, Department of Systems Ecology, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam (Netherlands); Aerts, R. [Institute of Ecological Science, Department of Systems Ecology, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam (Netherlands)

    2005-11-15

    We investigated concentrations of Zn, Cu, Cd and Pb in the compartments of a soil-plant (Urtica dioica)-snail (Cepaea nemoralis) food chain in four polluted locations in the Biesbosch floodplains, the Netherlands, and two reference locations. Total soil metal concentrations in the polluted locations were 4-20 times higher than those in the reference locations. Positive relationships between the generally low leaf concentrations and the soil concentrations were found for Zn only (r {sup 2} = 0.20). Bioaccumulation of Zn, Cu and Cd was observed in the snail tissues. We found positive relationships between the snail and leaf concentrations for all metals (range r {sup 2} = 0.19-0.46). The relationships between soil and snail concentrations were also positive, except for Cu (range r {sup 2} = 0.15-0.33). These results suggest transfer of metals to C. nemoralis snails from U. dioica leaves and from the soil. Metal transfer from polluted leaves to C. nemoralis is more important than transfer from the soil. - Bioaccumulation and positive snail-leaf relationships suggest metal transfer from Urtica dioica leaves to Cepaea nemoralis snails.

  8. Heavy metal concentrations in a soil-plant-snail food chain along a terrestrial soil pollution gradient

    International Nuclear Information System (INIS)

    Notten, M.J.M.; Oosthoek, A.J.P.; Rozema, J.; Aerts, R.

    2005-01-01

    We investigated concentrations of Zn, Cu, Cd and Pb in the compartments of a soil-plant (Urtica dioica)-snail (Cepaea nemoralis) food chain in four polluted locations in the Biesbosch floodplains, the Netherlands, and two reference locations. Total soil metal concentrations in the polluted locations were 4-20 times higher than those in the reference locations. Positive relationships between the generally low leaf concentrations and the soil concentrations were found for Zn only (r 2 = 0.20). Bioaccumulation of Zn, Cu and Cd was observed in the snail tissues. We found positive relationships between the snail and leaf concentrations for all metals (range r 2 = 0.19-0.46). The relationships between soil and snail concentrations were also positive, except for Cu (range r 2 = 0.15-0.33). These results suggest transfer of metals to C. nemoralis snails from U. dioica leaves and from the soil. Metal transfer from polluted leaves to C. nemoralis is more important than transfer from the soil. - Bioaccumulation and positive snail-leaf relationships suggest metal transfer from Urtica dioica leaves to Cepaea nemoralis snails

  9. Trace Element Concentrations in Tree Leaves and Lichen Collected Along a Metal Pollution Gradient Near Olkusz (Southern Poland).

    Science.gov (United States)

    Zakrzewska, Marta; Klimek, Beata

    2018-02-01

    The aim of the study was to assess the metal pollution in the vicinity of the Bukowno smelter near Olkusz in southern Poland. Birch and oak leaves, pine needles and a lichen Hypogymnia physodes, overgrowing pine bark were collected at stands at different distances from the smelter and analysed for cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) content. Concentrations of metals in the lichen were usually higher than in the tree leaves/needles and decreased with distance from the smelter, apart from the Cu content. The strongest correlation was noticed between Cd and Pb concentrations, which indicates a common pollution source (the smelter). Our results show that birch leaves can be potentially useful as a bioindicator of Zn air pollution since this species was shown to accumulate high amounts of zinc, related to environmental pollution with that metal, in their leaves.

  10. Spatial Variations of Heavy Metals in the Soils of Vegetable-Growing Land along Urban-Rural Gradient of Nanjing, China

    Science.gov (United States)

    Fang, Shi-Bo; Hu, Hao; Sun, Wan-Chun; Pan, Jian-Jun

    2011-01-01

    China has experienced rapid urbanization in recent years. The acceleration of urbanization has created wealth and opportunity as well as intensified ecological and environmental problems, especially soil pollution. Our study concentrated on the variation of heavy metal content due to urbanization in the vegetable-growing soil. Laws and other causes of the spatial-temporal variation in heavy metal content of vegetable-growing soils were analyzed for the period of urbanization in Nanjing (the capital of Jiangsu province in China). The levels of Cu, Zn, Pb, Cd and Hg in samples of vegetable-growing soil were detected. The transverse, vertical spatio-temporal variation of heavy metals in soil was analyzed on the base of field investigations and laboratory analysis. The results show that: (1) in soil used for vegetable production, the levels of heavy metals decreased gradually from urban to rural areas; the levels of the main heavy metals in urban areas are significantly higher than suburban and rural areas; (2) the means of the levels of heavy metals, calculated by subtracting the sublayer (15–30 cm) from the toplayer (0–15 cm), are all above zero and large in absolute value in urban areas, but in suburban and rural areas, the means are all above or below zero and small in absolute value. The causes of spatial and temporal variation were analyzed as follows: one cause was associated with mellowness of the soil and the length of time the soil had been used for vegetable production; the other cause was associated with population density and industrial intensity decreasing along the urban to rural gradient (i.e., urbanization levels can explain the distribution of heavy metals in soil to some extent). Land uses should be planned on the basis of heavy metal pollution in soil, especially in urban and suburban regions. Heavily polluted soils have to be expected from food production. Further investigation should be done to determine whether and what kind of agricultural

  11. The impact of heavy metal pollution gradients in sediments on benthic macrofauna at population and community levels

    International Nuclear Information System (INIS)

    Ryu, Jongseong; Khim, Jong Seong; Kang, Seong-Gil; Kang, Daeseok; Lee, Chang-hee; Koh, Chul-hwan

    2011-01-01

    The effect of sediment pollution on benthos was investigated in the vicinity of a large sewage treatment outflow at Incheon North Harbor, Korea. Animal size, vertical distribution and standard community parameters were analyzed along a 3 km transect line (n = 7). Univariate parameters showed a general trend of increasing species diversity with increasing distance from the pollution source. Multi-dimensional scaling analysis led to the clear separation of 3 locational groups, supporting gradient-dependent faunal composition. The innermost location was dominated by small sub-surface dwellers while the outer locations by large mid to deep burrowers. Looking for the size-frequency distribution, most abundance species (Heteromastus filiformis) showed the presence of larger size animals with increasing proximity to the pollution source. Meanwhile, species-specific vertical distributions, regardless of the pollution gradient, indicated that such shifts were due to species replacement resulting from a higher tolerance to pollutants over some species. - Highlights: → Hypotheses on benthic responses to sediment pollution were tested. → Decrease of species diversity with the proximity to the pollution source. → Shift of vertical distribution along the transect line attributes to species replacement. → Larger-size species occurred distant from the pollution source. → Larger individuals of Heteromastus filiformis occurred closer to the pollution source. - Community and population level response to the polluted environment of the harbor reflected an integration effect, together with biological interactions.

  12. Heavy metal concentrations in a soil-plant-snail food chain along a terrestrial soil pollution gradient.

    NARCIS (Netherlands)

    Notten, M.J.M.; Oosthoek, A.; Rozema, J.; Aerts, R.

    2005-01-01

    We investigated concentrations of Zn, Cu, Cd and Pb in the compartments of a soil-plant (Urtica dioica)-snail (Cepaea nemoralis) food chain in four polluted locations in the Biesbosch floodplains, the Netherlands, and two reference locations. Total soil metal concentrations in the polluted locations

  13. Solid phase extraction of Cd(II) and Pb(II) using a magnetic metal-organic framework, and their determination by FAAS

    International Nuclear Information System (INIS)

    Sohrabi, Mahmoud Reza; Matbouie, Zahra; Asgharinezhad, Ali Akbar; Dehghani, Ali

    2013-01-01

    We describe a novel magnetic metal-organic framework (MOF) for the preconcentration of Cd(II) and Pb(II) ions. The MOF was prepared from the Fe 3 O 4 -pyridine conjugate and the copper(II) complex of trimesic acid. The MOF was characterized by IR spectroscopy, elemental analysis, SEM and XRD. A Box-Behnken design through response surface methodology and experimental design was used to identify the optimal parameters for preconcentration. Extraction time, amount of magnetic MOF and pH value were found to be critical factors for uptake, while type, volume, concentration of eluent, and elution time are critical in the elution step. The ions were then determined by FAAS. The limits of detection are 0.2 and 1.1 μg L −1 for Cd(II), and Pb(II) ions, respectively, relative standard deviations are −1 of Cd(II) and Pb(II) ions), and the enrichment capacity of the MOF is at around 190 mg g −1 for both ions which is higher than the conventional Fe 3 O 4 -pyridine material. The magnetic MOF was successfully applied to the rapid extraction of trace quantities of Cd(II) and Pb(II) ions in fish, sediment, and water samples. (author)

  14. Liquid metal reactor deactivation as applied to the experimental breeder reactor - II

    International Nuclear Information System (INIS)

    Earle, O. K.; Michelbacher, J. A.; Pfannenstiel, D. F.; Wells, P. B.

    1999-01-01

    The Experimental Breeder Reactor-II (EBR-II) at Argonne National Laboratory-West (ANL-W) was shutdown in September, 1994. This sodium cooled reactor had been in service since 1964, and by the US Department of Energy (DOE) mandate, was to be placed in an industrially and radiologically safe condition for ultimate decommissioning. The deactivation of a liquid metal reactor presents unique concerns. The first major task associated with the project was the removal of all fueled assemblies. In addition, sodium must be drained from systems and processed for ultimate disposal. Residual quantities of sodium remaining in systems must be deactivated or inerted to preclude future hazards associated with pyrophoricity and generation of potentially explosive hydrogen gas. A Sodium Process Facility (SPF) was designed and constructed to react the elemental sodium from the EBR-II primary and secondary systems to sodium hydroxide for disposal. This facility has a design capacity to allow the reaction of the complete inventory of sodium at ANL-W in less than two years. Additional quantities of sodium from the Fermi-1 reactor are also being treated at the SPF

  15. Calcium and sodium as regulators of the recovery of four Daphnia species along a gradient of metal and base cations in metal contaminated lakes in Sudbury, Ontario, Canada

    Directory of Open Access Journals (Sweden)

    Martha Patricia Celis-Salgado

    2016-04-01

    Full Text Available Smelting of sulphur-rich metallic ores in Sudbury, Ontario, Canada, has caused acidification and metal contamination of thousands of lakes in the region. Recent reductions in smelter emissions have resulted in much ecological recovery, but the recovery of Daphnia species has been poor. To determine if Cu and Ni toxicity could explain differences in daphniid recovery among lakes, we compared results of 14 d static with renewal bioassays in waters from Blue Chalk Lake, an uncontaminated reference lake 200 km from Sudbury, and from five Sudbury lakes ranging in distance from the smelters and varying in metal and cation concentrations. We spiked Blue Chalk Lake water with Cu and Ni to levels resembling those of the Sudbury lakes and also tested the lake waters for toxicity. Survival of Daphnia pulex, D. pulicaria and D. mendotae decreased monotonically with increasing metal concentrations in the spiked Blue Chalk Lake treatments, falling from 90% in the controls to 0% at the two highest Cu and Ni levels, reflecting levels of Middle and Hannah lakes. In contrast, survival in waters collected from the actual Sudbury lakes did not monotonically track their total metal concentrations. Rather, survival fell to 0% in Clearwater Lake water, a lake with intermediate metal contamination (8.9 and 79.9 μg L–1 of Cu and Ni, respectively vs 70-100% in the other lakes. We performed an additional assay with Clearwater Lake waters increasing its Ca and Na concentrations, singly and in combination to levels that reflected the levels in Middle Lake. The survival of the four daphniid species increased from 0% up to 80-100% with added Ca and from 0% to 60-90% with added Na. Lipid-ovarian indices had a similar trend to survival for D. mendotae and D. pulicaria in Bioassay 1, varying with the cation concentrations in the lakes for the daphniids in Bioassay 2. The bioassays results imply that regional recovery patterns of daphniids in Sudbury lakes cannot be understood

  16. Influence of plasma pressure gradient on melt layer macroscopic erosion of metal targets in disruption simulation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Tereshin, V.I.; Garkusha, I.E. E-mail: garkusha@ipp.kharkov.ua; Bandura, A.N.; Byrka, O.V.; Chebotarev, V.V.; Makhlaj, V.A.; Solyakov, D.G.; Wuerz, H

    2003-03-01

    Melt layer erosion of metal targets under pulsed high heat loads is discussed. Tungsten, copper, aluminum, and titanium targets were exposed to perpendicular and inclined plasma impact in the quasi-steady-state plasma accelerator QSPA Kh-50. Melt layer motion results in erosion crater formation with rather large mountains of the resolidified material at the crater edge. It is shown that macroscopic motion of the melt layer and surface cracking are the main factors responsible for tungsten erosion.

  17. Influence of plasma pressure gradient on melt layer macroscopic erosion of metal targets in disruption simulation experiments

    International Nuclear Information System (INIS)

    Tereshin, V.I.; Garkusha, I.E.; Bandura, A.N.; Byrka, O.V.; Chebotarev, V.V.; Makhlaj, V.A.; Solyakov, D.G.; Wuerz, H.

    2003-01-01

    Melt layer erosion of metal targets under pulsed high heat loads is discussed. Tungsten, copper, aluminum, and titanium targets were exposed to perpendicular and inclined plasma impact in the quasi-steady-state plasma accelerator QSPA Kh-50. Melt layer motion results in erosion crater formation with rather large mountains of the resolidified material at the crater edge. It is shown that macroscopic motion of the melt layer and surface cracking are the main factors responsible for tungsten erosion

  18. A plasmid containing the human metallothionein II gene can function as an antibody-assisted electrophoretic biosensor for heavy metals.

    Science.gov (United States)

    Wooten, Dennis C; Starr, Clarise R; Lyon, Wanda J

    2016-01-01

    Different forms of heavy metals affect biochemical systems in characteristic ways that cannot be detected with typical metal analysis methods like atomic absorption spectrometry. Further, using living systems to analyze interaction of heavy metals with biochemical systems can be laborious and unreliable. To generate a reliable easy-to-use biologically-based biosensor system, the entire human metallothionein-II (MT-II) gene was incorporated into a plasmid (pUC57-MT) easily replicated in Escherichia coli. In this system, a commercial polyclonal antibody raised against human metal-responsive transcription factor-1 protein (MTF-1 protein) could modify the electrophoretic migration patterns (i.e. cause specific decreases in agarose gel electrophoretic mobility) of the plasmid in the presence or absence of heavy metals other than zinc (Zn). In the study here, heavy metals, MTF-1 protein, and polyclonal anti-MTF-1 antibody were used to assess pUC57-MT plasmid antibody-assisted electrophoretic mobility. Anti-MTF-1 antibody bound both MTF-1 protein and pUC57-MT plasmid in a non-competitive fashion such that it could be used to differentiate specific heavy metal binding. The results showed that antibody-inhibited plasmid migration was heavy metal level-dependent. Zinc caused a unique mobility shift pattern opposite to that of other metals tested, i.e. Zn blocked the antibody ability to inhibit plasmid migration, despite a greatly increased affinity for DNA by the antibody when Zn was present. The Zn effect was reversed/modified by adding MTF-1 protein. Additionally, antibody inhibition of plasmid mobility was resistant to heat pre-treatment and trypsinization, indicating absence of residual DNA extraction-resistant bacterial DNA binding proteins. DNA binding by anti-DNA antibodies may be commonly enhanced by xenobiotic heavy metals and elevated levels of Zn, thus making them potentially effective tools for assessment of heavy metal bioavailability in aqueous solutions and

  19. MODIFICATION OF KELUD VOLCANIC ASH 2014 AS SELECTIVE ADSORBENT MATERIAL FOR COPPER(II METAL ION

    Directory of Open Access Journals (Sweden)

    Susila Kristianingrum

    2017-01-01

      This research aims to prepare an adsorbent from Kelud volcanic ash for better Cu(II adsorption efficiency than Kiesel gel 60G E'Merck. Adsorbent synthesis was done by dissolving 6 grams of volcanic ash activated 700oC 4 hours and washed with HCl 0.1 M into 200 ml of 3M sodium hydroxide with stirring and heating of 100 °C for 1 hour. The filtrate sodium silicate was then neutralized using sulfuric acid. The mixture was allowed to stand for 24 hours then filtered and washed with aquaDM, then dried and crushed. The procedure is repeated for nitric acid, acetic acid and formic acid with a contact time of 24 hours. The products were then characterized using FTIR and XRD, subsequently determined acidity, moisture content, and tested for its adsorption of the ion Cu (II with AAS. The results showed that the type of acid that produced highest rendemen is AK-H2SO4-3M ie 36.93%, acidity of the adsorbent silica gel synthesized similar to Kiesel gel 60G E'Merck ie adsorbent AK-CH3COOH-3M and the water content of the silica gel adsorbent synthesized similar to Kiesel gel 60G E'Merck ie adsorbent AK-H2SO4-2 M. The character of the functional groups of silica gel synthesized all have similarities with Kiesel gel 60G E'Merck as a comparison. Qualitative analysis by XRD for all modified adsorbent showed a dominant peak of SiO2 except adsorbent AK-H2SO4 amorphous and chemical bonds with FTIR indicates that it has formed a bond of Si-O-Si and Si-OH. The optimum adsorption efficiency of the metal ions Cu(II obtained from AK-H2SO4-5M adsorbent that is equal to 93.2617% and the optimum adsorption capacity of the Cu(II metal ions was obtained from the adsorbent AK-CH3COOH-3M is equal to 2.4919 mg/ g.   Keywords: adsorbents, silica gel, adsorption, kelud volcanic ash

  20. Effects of Pop III to PopII transition on the lowest metallicity stars in dwarf galaxies

    Science.gov (United States)

    Zhang, Yimiao; Keres, Dusan; FIRE Team

    2018-01-01

    We examine the effects of the enrichments from Population III (Pop III) stars on the formation and properties of the first generation of the Population II (Pop II) stars. Pop III stars begin to transition towards Pop II stars when the metals dispersed in Pop III supernovae pollute the nearby gas. However, details of this transition are still largely unknown. We use dwarf galaxy simulations from the Feedback In Realistic Environments (FIRE) project to identify the star-forming gas that is likely to be pre-enriched by Pop III supernovae and follow the stars that form in such gas. This pre-enrichment will leave the signature in the lowest metallicity stars that can be used to better constrain the details of the Pop III-to-Pop II transition.

  1. Direct Synthesis of 7 nm Thick Zinc(II)-Benzimidazole-Acetate Metal-Organic Framework Nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Feng; Kumar, Prashant; Xu, Wenqian; Mkhoyan, K. Andre; Tsapatsis, Michael

    2018-01-09

    Two-dimensional metal-organic frameworks (MOFs) are promising candidates for high performance gas sepa-ration membranes. Currently, MOF nanosheets are mostly fabricated through delamination of layered MOFs, which often re-sults in a low yield of intact free-standing nanosheets. In this work, we present a direct synthesis method for zinc(II)-benzimidazole-acetate (Zn(Bim)OAc) MOF nanosheets. The obtained nanosheets have a lateral dimension of 600 nm when synthesized at room temperature. By adjusting the synthesis temperature, the morphology of obtained nanosheets can be readily tuned from nanosheets to nanobelts. A thickness of 7 nm is determined for Zn(Bim)OAc using high-angle annular dark-field scanning transmission electron microscopy, which makes these nanosheets promising building blocks of gas sepa-ration membranes.

  2. Temperature gradient compatibility tests of some refractory metals and alloys in bismuth and bismuth--lithium solutions

    International Nuclear Information System (INIS)

    DiStefano, J.R.; Cavin, O.B.

    1976-11-01

    Quartz, T-111, and Mo thermal-convection loop tests were conducted at temperatures up to 700 0 C (100 0 C ΔT) to determine the compatibility of several refractory metals/alloys with bismuth and bismuth-lithium solutions for molten salt breeder reactor applications. Methods of evaluation included weight change measurements, metallographic examination, chemical and electron microprobe analysis, and mechanical properties tests. Molybdenum, T-111, and TA--10 percent W appear to be the most promising containment materials, while niobium and iron-based alloys are unacceptable

  3. HIGH-RESOLUTION SPECTROSCOPY OF EXTREMELY METAL-POOR STARS IN THE LEAST EVOLVED GALAXIES: BOÖTES II

    International Nuclear Information System (INIS)

    Ji, Alexander P.; Frebel, Anna; Simon, Joshua D.; Geha, Marla

    2016-01-01

    We present high-resolution Magellan/MIKE spectra of the four brightest confirmed red giant stars in the ultra-faint dwarf galaxy Boötes II (Boo II). These stars all inhabit the metal-poor tail of the Boo II metallicity distribution function. The chemical abundance pattern of all detectable elements in these stars is consistent with that of the Galactic halo. However, all four stars have undetectable amounts of neutron-capture elements Sr and Ba, with upper limits comparable to the lowest ever detected in the halo or in other dwarf galaxies. One star exhibits significant radial velocity variations over time, suggesting it to be in a binary system. Its variable velocity has likely increased past determinations of the Boo II velocity dispersion. Our four stars span a limited metallicity range, but their enhanced α-abundances and low neutron-capture abundances are consistent with the interpretation that Boo II has been enriched by very few generations of stars. The chemical abundance pattern in Boo II confirms the emerging trend that the faintest dwarf galaxies have neutron-capture abundances distinct from the halo, suggesting the dominant source of neutron-capture elements in halo stars may be different than in ultra-faint dwarfs

  4. Spatiotemporal variations in metal accumulation, RNA/DNA ratio and energy reserve in Perna viridis transplanted along a marine pollution gradient in Hong Kong.

    Science.gov (United States)

    Yeung, Jamius W Y; Zhou, Guang-Jie; Leung, Kenneth M Y

    2017-11-30

    We examined spatiotemporal variations of metal levels and three growth related biomarkers, i.e., RNA/DNA ratio (RD), total energy reserve (Et) and condition index (CI), in green-lipped mussels Perna viridis transplanted into five locations along a pollution gradient in the marine environment of Hong Kong over 120days of deployment. There were significant differences in metal levels and biomarker responses among the five sites and six time points. Mussels in two clean sites displayed better CI and significantly lower levels of Ag, Cu, Pb and Zn in their tissues than the other sites. Temporal patterns of RD in P. viridis were found to be site-specific. Across all sites, Et decreased in P. viridis over the deployment period, though the rate of decrease varied significantly among the sites. Therefore, temporal variation of biomarkers should be taken to consideration in mussel-watch programs because such information can help discriminate pollution-induced change from natural variation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Recovery of high-purity metallic Pd from Pd(II)-sorbed biosorbents by incineration.

    Science.gov (United States)

    Won, Sung Wook; Lim, Areum; Yun, Yeoung-Sang

    2013-06-01

    This work reports a direct way to recover metallic palladium with high purity from Pd(II)-sorbed polyethylenimine-modified Corynebacterium glutamicum biosorbent using a combined method of biosorption and incineration. This study is focused on the incineration part which affects the purity of recovered Pd. The incineration temperature and the amount of Pd loaded on the biosorbent were considered as major factors in the incineration process, and their effects were examined. The results showed that both factors significantly affected the enhancement of the recovery efficiency and purity of the recovered Pd. SEM-EDX and XRD analyses were used to confirm that Pd phase existed in the ash. As a result, the recovered Pd was changed from PdO to zero-valent Pd as the incineration temperature was increased from 600 to 900°C. Almost 100% pure metallic Pd was recovered with recovery efficiency above 99.0% under the conditions of 900°C and 136.9 mg/g. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Sulfide precipitation method of separating uranium from Group II and Group III metal ions

    International Nuclear Information System (INIS)

    Sundar, P.S.

    1977-01-01

    Uranium is separated from analytical Group II and Group III metal ions in an aqueous liquor containing uranyl ions. The liquor is extracted with a non-interfering, water-immiscible, organic solvent containing a reagent which will react with the uranyl ions to form a complex soluble in the solvent. If the liquor is acidic, the solvent is washed with water. Then to the solvent is added an aqueous solution containing about 0.5 to 1.0 mole per liter of (NH 4 ) 2 CO 3 or NH 4 HCO 3 ions and sufficient sulfide ions to precipitate the metal ions as sulfides. The solvent and the aqueous solution are separated and the sulfides filtered from the aqueous solution. The ammonium-uranyl-tricarbonate in the aqueous solution can then be precipitated by increasing the concentration of (NH 4 ) 2 CO 3 or NH 4 HCO 3 ions to about 1.5 to 2.5 moles per liter. The precipitate is filtered and calcined to obtain U 3 O 8 or UO 2 . 21 claims, 1 figure

  7. The prediction of creep damage in Type 347 weld metal: part II creep fatigue tests

    International Nuclear Information System (INIS)

    Spindler, M.W.

    2005-01-01

    Calculations of creep damage under conditions of strain control are often carried out using either a time fraction approach or a ductility exhaustion approach. In part I of this paper the rupture strength and creep ductility data for a Type 347 weld metal were fitted to provide the material properties that are used to calculate creep damage. Part II of this paper examines whether the time fraction approach or the ductility exhaustion approach gives the better predictions of creep damage in creep-fatigue tests on the same Type 347 weld metal. In addition, a new creep damage model, which was developed by removing some of the simplifying assumptions that are made in the ductility exhaustion approach, was used. This new creep damage model is a function of the strain rate, stress and temperature and was derived from creep and constant strain rate test data using a reverse modelling technique (see part I of this paper). It is shown that the new creep damage model gives better predictions of creep damage in the creep-fatigue tests than the time fraction and the ductility exhaustion approaches

  8. Mutational analysis of divalent metal ion binding in the active site of class II α-mannosidase from sulfolobus solfataricus

    DEFF Research Database (Denmark)

    Hansen, Dennis K.; Webb, Helen; Nielsen, Jonas Willum

    2015-01-01

    Mutational analysis of Sulfolobus solfataricus class II α-mannosidase was focused on side chains that interact with the hydroxyls of the-1 mannosyl of the substrate (Asp-534) or form ligands to the active site divalent metal ion (His-228 and His-533) judged from crystal structures of homologous e......, although less dramatically with some activating metal ions. No major differences in the pH dependence between wild-type and mutant enzymes were found in the presence of different metal ions. The pH optimum was 5, but enzyme instability was observed at pH...

  9. Multi-objective Optimization of Pulsed Gas Metal Arc Welding Process Using Neuro NSGA-II

    Science.gov (United States)

    Pal, Kamal; Pal, Surjya K.

    2018-05-01

    Weld quality is a critical issue in fabrication industries where products are custom-designed. Multi-objective optimization results number of solutions in the pareto-optimal front. Mathematical regression model based optimization methods are often found to be inadequate for highly non-linear arc welding processes. Thus, various global evolutionary approaches like artificial neural network, genetic algorithm (GA) have been developed. The present work attempts with elitist non-dominated sorting GA (NSGA-II) for optimization of pulsed gas metal arc welding process using back propagation neural network (BPNN) based weld quality feature models. The primary objective to maintain butt joint weld quality is the maximization of tensile strength with minimum plate distortion. BPNN has been used to compute the fitness of each solution after adequate training, whereas NSGA-II algorithm generates the optimum solutions for two conflicting objectives. Welding experiments have been conducted on low carbon steel using response surface methodology. The pareto-optimal front with three ranked solutions after 20th generations was considered as the best without further improvement. The joint strength as well as transverse shrinkage was found to be drastically improved over the design of experimental results as per validated pareto-optimal solutions obtained.

  10. Multiobjective Optimization for Fixture Locating Layout of Sheet Metal Part Using SVR and NSGA-II

    Directory of Open Access Journals (Sweden)

    Yuan Yang

    2017-01-01

    Full Text Available Fixture plays a significant role in determining the sheet metal part (SMP spatial position and restraining its excessive deformation in many manufacturing operations. However, it is still a difficult task to design and optimize SMP fixture locating layout at present because there exist multiple conflicting objectives and excessive computational cost of finite element analysis (FEA during the optimization process. To this end, a new multiobjective optimization method for SMP fixture locating layout is proposed in this paper based on the support vector regression (SVR surrogate model and the elitist nondominated sorting genetic algorithm (NSGA-II. By using ABAQUS™ Python script interface, a parametric FEA model is established. And the fixture locating layout is treated as design variables, while the overall deformation and maximum deformation of SMP under external forces are as the multiple objective functions. First, a limited number of training and testing samples are generated by combining Latin hypercube design (LHD with FEA. Second, two SVR prediction models corresponding to the multiple objectives are established by learning from the limited training samples and are integrated as the multiobjective optimization surrogate model. Third, NSGA-II is applied to determine the Pareto optimal solutions of SMP fixture locating layout. Finally, a multiobjective optimization for fixture locating layout of an aircraft fuselage skin case is conducted to illustrate and verify the proposed method.

  11. The roles of EBR-II and TREAT [Transient Reactor Test] in establishing liquid metal reactor safety

    International Nuclear Information System (INIS)

    Sackett, J.I.; Lehto, W.K.; Solbrig, C.W.

    1990-01-01

    This paper examines the role of the Experimental Breeder Reactor II (EBR-II) and Transient Reactor Test (TREAT) facilities in contributing to the understanding and resolution of key safety issues in liquid metal reactor safety during the decade of the 80's. Fuels and materials testing has been carried out to address questions on fuels behavior during steady-state and upset conditions. In addition, EBR-II has conducted plant tests to demonstrate passive response to ATWS events and to develop control and diagnostic strategies for safe operation of advanced LMRs. TREAT and EBR-II complement each other and between them provide a transient testing capability that covers the whole range of concerns during overpower conditions. EBR-II, with use of the special Automatic Control Rod Drive System, can generate power change rates that overlap the lower end of the TREAT capability. 21 refs

  12. Non-noble metal graphene oxide-copper (II) ions hybrid electrodes for electrocatalytic hydrogen evolution reaction

    KAUST Repository

    Muralikrishna, S.; Ravishankar, T.N.; Ramakrishnappa, T.; Nagaraju, Doddahalli H.; Krishna Pai, Ranjith

    2015-01-01

    Non-noble metal and inexpensive graphene oxide-copper (II) ions (GO-Cu2+) hybrid catalysts have been explored for the hydrogen evolution reaction (HER). We were able to tune the binding abilities of GO toward the Cu2+ ions and hence their catalytic

  13. Improved recovery of trace amounts of gold (III), palladium (II) and platinum (IV) from large amounts of associated base metals using anion-exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Matsubara, I. [Lab. of Chemistry, Tokyo Women' s Medical Univ. (Japan); Takeda, Y.; Ishida, K. [Lab. of Chemistry, Nippon Medical School, Kawasaki-shi, Kanagawa-ken (Japan)

    2000-02-01

    The adsorption and desorption behaviors of gold (III), palladium (II) and platinum (IV) were surveyed in column chromatographic systems consisting of one of the conventional anion-exchange resins of large ion-exchange capacity and dilute thiourea solutions. The noble metals were strongly adsorbed on the anion-exchange resins from dilute hydrochloric acid, while most base metals did not show any marked adsorbability. These facts made it possible to separate the noble metals from a large quantity of base metals such as Ag (I), Al (III), Co (II), Cu (II), Fe (III), Mn (II), Ni (II), Pb (II), and Zn (II). Although it used to be very difficult to desorb the noble metals from the resins used, the difficulty was easily overcome by use of dilute thiourea solutions as an eluant. In the present study, as little as 1.00 {mu}g of the respective noble metals was quantitatively separated and recovered from as much as ca. 10 mg of a number of metals on a small column by elution with a small amount of dilute thiourea solution. The present systems should be applicable to the separation, concentration and recovery of traces of the noble metals from a number of base metals coexisting in a more extended range of amounts and ratios. (orig.)

  14. The removal of toxic metals from liquid effluents by ion exchange resins. Part II: cadmium(II/ sulphate/Lewatit TP260

    Directory of Open Access Journals (Sweden)

    Alguacil, F. J.

    2002-10-01

    Full Text Available The adsorption of cadmium (II, from aqueous sulphate solutions, on Lewatit TP260 resin has been investigated in batch equilibrium experiments. The influence of pH and temperature on metal adsorption capacity have also been examined. The kinetic performance of the resin has been assesed and the results have been correlated by the pore diffusion model. The resin has been used in mini-columns to study its performance under dynamics conditions. The desorption of metal ion is achieved using sulphuric acid (0.25M and 0.5M.

    Se estudia la adsorción de cadmio(II, de disoluciones en medio sulfato, sobre la resina Lewatit TP260. La adsorción del metal se ha investigado en función del pH, la temperatura y el tiempo de contacto con la resina. Los estudios cinéticos permiten correlacionar el proceso de intercambio iónico con el modelo de difusión en poro. Se ha empleado el sistema en mini columnas para evaluar el comportamiento de la resina bajo condiciones dinámicas. La desorción del metal se lleva a cabo con disoluciones de ácido sulfúrico (0,25M y 0,5M.

  15. Syntheses, structural characterization and spectroscopic studies of cadmium(II)-metal(II) cyanide complexes with 4-(2-aminoethyl)pyridine

    Science.gov (United States)

    Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla; Şenyel, Mustafa; Hökelek, Tuncer

    2017-02-01

    Three new cadmium(II)-metal(II) cyanide complexes, [Cd(4aepy)2(H2O)2][Ni(CN)4] (1), [Cd(4aepy)2(H2O)2][Pd(CN)4] (2) and [Cd(4aepy)2(H2O)2][Pt(CN)4] (3) [4aepy = 4-(2-aminoethyl)pyridine], have been synthesized and characterized by elemental, thermal, FT-IR and Raman spectral analyses. The crystal structures of 1 and 2 have been determined by single crystal X-ray diffraction technique, in which they crystallize in the monoclinic system and C2/c space group. The M(II) [M(II) = Ni(II), Pd(II) and Pt(II)] ions are coordinated with the carbon atoms of the four cyanide groups in the square planar geometries and the [M(CN)4]2- ions act as counter ions. The Cd(II) ions display an N4O2 coordination sphere with a distorted octahedral geometry, the nitrogen donors belonging to four molecules of the organic 4aepy that act as unidentate ligands and two oxygen atoms from aqua ligands. 3D supramolecular structures of 1 and 2 were occurred by M⋯π and hydrogen bonding (Nsbnd H⋯N and Osbnd H⋯N) interactions. Vibrational assignments of all the observed bands were given and the spectral properties were also supported the crystal structures of the complexes. A possible decompositions of the complexes were investigated in the temperature range 30-800 °C in the static atmosphere.

  16. Metal based biologically active compounds: Design, synthesis, DNA binding and antidiabetic activity of 6-methyl-3-formyl chromone derived hydrazones and their metal (II) complexes.

    Science.gov (United States)

    Philip, Jessica Elizabeth; Shahid, Muhammad; Prathapachandra Kurup, M R; Velayudhan, Mohanan Puzhavoorparambil

    2017-10-01

    Two chromone hydrazone ligands HL 1 and HL 2 were synthesized and characterized by elemental analyses, IR, 1 H NMR & 13 C NMR, electronic absorption and mass spectra. The reactions of the chromone hydrazones with transition metals such as Ni, Cu, and Zn (II) salts of acetate afforded mononuclear metal complexes. Characterization and structure elucidation of the prepared chromone hydrazone metal (II) complexes were done by elemental, IR, electronic, EPR spectra and thermo gravimetric analyses as well as conductivity and magnetic susceptibility measurements. The spectroscopic data showed that the ligand acts as a mono basic bidentate with coordination sites are azomethine nitrogen and hydrazonic oxygen, and they exhibited distorted geometry. The biological studies involved antidiabetic activity i.e. enzyme inhibition of α-amylase and α-glucosidase, Calf Thymus - DNA (CT-DNA) interaction and molecular docking. Potential capacity of synthesized compounds to inhibit the α-amylase and α-glucosidase activity was assayed whereas DNA interaction studies were carried out with the help UV-Vis absorption titration and viscosity method. The docking studies of chromone hydrazones show that they are minor groove binders. Complexes were found to be good DNA - intercalates. Chromone hydrazones and its transition metal complexes have shown comparable antidiabetic activity with a standard drug acarbose. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Liquid Metallic Hydrogen II. A Critical Assessment of Current and Primordial Helium Levels in the Sun

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-04-01

    lar winds which, though highly variable, provide a wealth of data. Evaluations of pr imordial helium levels based on 1 the spectroscopic study of H-II regions and 2 microwav e anisotropy data, re- main highly questionable. Current helium levels, both with in the stars (Robitaille J. C. and Robitaille P.-M. Liquid Metallic Hydrogen III. Interca lation and Lattice Exclusion versus Gravitational Settling, and Their Consequences Rel ative to Internal Structure, Surface Activity, and Solar Winds in the Sun. Progr. Phys. , 2013, v. 2, in press and the universe at large, appear to be overstated. A careful con sideration of available ob- servational data suggests that helium abundances are consi derably lower than currently believed.

  18. Disturbances to metal partitioning during toxicity testing of iron(II)-rich estuarine pore waters and whole sediments.

    Science.gov (United States)

    Simpson, Stuart L; Batley, Graeme E

    2003-02-01

    Metal partitioning is altered when suboxic estuarine sediments containing Fe(II)-rich pore waters are disturbed during collection, preparation, and toxicity testing. Experiments with model Fe(II)-rich pore waters demonstrated the rates at which adsorptive losses of Cd, Cu, Ni, Mn, Pb, and Zn occur upon exposure to air. Experiments with Zn-contaminated estuarine sediments demonstrated large and often unpredictable changes to metal partitioning during sediment storage, removal of organisms, and homogenization before testing. Small modifications to conditions, such as aeration of overlying waters, caused large changes to the metal partitioning. Disturbances caused by sediment collection required many weeks for reestablishment of equilibrium. Bioturbation by benthic organisms led to oxidation of pore-water Fe(II) and lower Zn fluxes because of the formation of Fe hydroxide precipitates that adsorb pore-water Zn. For five weeks after the addition of organisms to sediments, Zn fluxes increased slowly as the organisms established themselves in the sediments, indicating that the establishment of equilibrium was not rapid. The results are discussed in terms of the dynamic nature of suboxic, Fe(II)-rich estuarine sediments, how organisms perturb their environment, and the importance of understanding chemistry in toxicity testing with whole sediments or pore water. Recommendations are provided for the handling of sediments for toxicity testing.

  19. Heavy metal contents of road-deposited sediment along the urban-rural gradient around Beijing and its potential contribution to runoff pollution.

    Science.gov (United States)

    Zhao, Hongtao; Li, Xuyong; Wang, Xiaomei

    2011-09-01

    Understanding the contribution of road-deposited sediment (RDS) and its washoff process is essential for controlling urban runoff pollution. Ninety-seven RDS samples were collected along the urban-suburban-rural gradient from areas of five administrative units in the Beijing metropolitan region, including central urban (UCA), urban village (UVA), central suburban county (CSA), rural town (RTA), and rural village (RVA) areas. RDS washoff was evaluated with different particle sizes using a rainfall simulator. Heavy metal elements (i.e., Cr, Cu, Ni, Pb, and Zn) were estimated in both RDS and runoff samples. The RDS mass per unit area increased in the order UCA (21 ± 24 g/m(2)) ≈ CSA (20 ± 16 g/m(2)) runoff pollution contributions per unit area. Our findings imply that controlling the first flush in the UCA and CSA, and improving existing street cleaning methods and road surface conditions in the TRA, UVA, and RVA will be appropriate strategies for controlling runoff pollution from RDS.

  20. Gene expression analysis of 4 biomarker candidates in Eisenia fetida exposed to an environmental metallic trace elements gradient: A microcosm study

    Energy Technology Data Exchange (ETDEWEB)

    Brulle, Franck; Lemiere, Sebastien [Univ Lille Nord de France, F-59000 Lille (France); LGCgE, Equipe Ecologie Numerique et Ecotoxicologie, Lille 1, F-59650 Villeneuve d' Ascq (France); Waterlot, Christophe; Douay, Francis [Univ Lille Nord de France, F-59000 Lille (France); LGCgE, Equipe Sols et Environnement, Groupe ISA, 48 boulevard Vauban, F-59046 Lille Cedex (France); Vandenbulcke, Franck, E-mail: franck.vandenbulcke@univ-lille1.fr [Univ Lille Nord de France, F-59000 Lille (France); LGCgE, Equipe Ecologie Numerique et Ecotoxicologie, Lille 1, F-59650 Villeneuve d' Ascq (France)

    2011-11-15

    Past activities of 2 smelters (Metaleurop Nord and Nyrstar) led to the accumulation of high amounts of Metal Trace Elements (TEs) in top soils of the Noyelles-Godault/Auby area, Northern France. Earthworms were exposed to polluted soils collected in this area to study and better understand the physiological changes, the mechanisms of acclimation, and detoxification resulting from TE exposure. Previously we have cloned and transcriptionally characterized potential biomarkers from immune cells of the ecotoxicologically important earthworm species Eisenia fetida exposed in vivo to TE-spiked standard soils. In the present study, analysis of expression kinetics of four candidate indicator genes (Cadmium-metallothionein, coactosin like protein, phytochelatin synthase and lysenin) was performed in E. fetida after microcosm exposures to natural soils exhibiting an environmental cadmium (Cd) gradient in a kinetic manner. TE body burdens were also measured. This microcosm study provided insights into: (1) the ability of the 4 tested genes to serve as expression biomarkers, (2) detoxification processes through the expression analysis of selected genes, and (3) influence of land uses on the response of potential biomarkers (gene expression or TE uptake). - Highlights: {yields} Expression biomarkers in animals exposed to Cadmium-contaminated field soils. {yields} Expression kinetics to test the ability of genes to serve as expression biomarkers. {yields} Study of detoxification processes through the expression analysis of selected genes.

  1. Radial velocities and metallicities from infrared Ca ii triplet spectroscopy of open clusters. II. Berkeley 23, King 1, NGC 559, NGC 6603, and NGC 7245

    Science.gov (United States)

    Carrera, R.; Casamiquela, L.; Ospina, N.; Balaguer-Núñez, L.; Jordi, C.; Monteagudo, L.

    2015-06-01

    Context. Open clusters are key to studying the formation and evolution of the Galactic disc. However, there is a deficiency of radial velocity and chemical abundance determinations for open clusters in the literature. Aims: We intend to increase the number of determinations of radial velocities and metallicities from spectroscopy for open clusters. Methods: We acquired medium-resolution spectra (R ~ 8000) in the infrared region Ca ii triplet lines (~8500 Å) for several stars in five open clusters with the long-slit IDS spectrograph on the 2.5 m Isaac Newton Telescope (Roque de los Muchachos Observatory, Spain). Radial velocities were obtained by cross-correlation fitting techniques. The relationships available in the literature between the strength of infrared Ca ii lines and metallicity were also used to derive the metallicity for each cluster. Results: We obtain ⟨Vr⟩ = 48.6 ± 3.4, -58.4 ± 6.8, 26.0 ± 4.3, and -65.3 ± 3.2 km s-1 for Berkeley 23, NGC 559, NGC 6603, and NGC 7245, respectively. We found [ Fe/H ] = -0.25 ± 0.14 and -0.15 ± 0.18 for NGC 559 and NGC 7245, respectively. Berkeley 23 has low metallicity, [ Fe/H ] = -0.42 ± 0.13, which is similar to other open clusters in the outskirts of the Galactic disc. In contrast, we derived high metallicity ([ Fe/H ] = +0.43 ± 0.15) for NGC 6603, which places this system among the most metal-rich known open clusters. To our knowledge, this is the first determination of radial velocities and metallicities from spectroscopy for these clusters, except NGC 6603, for which radial velocities had been previously determined. We have also analysed ten stars in the line of sight to King 1. Because of the large dispersion obtained in both radial velocity and metallicity, we cannot be sure that we have sampled true cluster members. Based on observations made with the 2.5 m Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the

  2. Isolation Of PS II Nanoparticles And Oxygen Evolution Studies In Synechococcus Spp. PCC 7942 Under Heavy Metal Stress

    Science.gov (United States)

    Ahmad, Iffat Zareen; Sundaram, Shanthy; Tripathi, Ashutosh; Soumya, K. K.

    2009-06-01

    The effect of heavy metals was seen on the oxygen evolution pattern of a unicellular, non-heterocystous cyanobacterial strain of Synechococcus spp. PCC 7942. It was grown in a BG-11 medium supplemented with heavy metals, namely, nickel, copper, cadmium and mercury. Final concentrations of the heavy metal solution used in the culture were 0.1, 0.4 and 1 μM. All the experiments were performed in the exponential phase of the culture. Oxygen-evolving photosystem II (PS II) particles were purified from Synechococcus spp. PCC 7942 by a single-step Ni2+-affinity column chromatography after solubilization of thylakoid membranes with sucrose monolaurate. Oxygen evolution was measured with Clark type oxygen electrode fitted with a circulating water jacket. The light on the surface of the vessel was 10 w/m2. The cultures were incubated in light for 15 minutes prior to the measurement of oxygen evolution. Oxygen evolution was measured in assay mixture containing phosphate buffer (pH-7.5, 0.1 M) in the presence of potassium ferricyanide as the electron acceptor. The preparation from the control showed a high oxygen-evolving activity of 2, 300-2, 500 pmol O2 (mg Chl)-1 h-1 while the activity was decreased in the cultures grown with heavy metals. The inhibition of oxygen evolution shown by the organism in the presence of different metals was in the order Hg>Ni>Cd>Cu. Such heavy metal resistant strains will find application in the construction of PS II- based biosensors for the monitoring of pollutants.

  3. Structural and magnetic characterization of a tetranuclear copper(II) cubane stabilized by intramolecular metal cation-π interactions.

    Science.gov (United States)

    Papadakis, Raffaello; Rivière, Eric; Giorgi, Michel; Jamet, Hélène; Rousselot-Pailley, Pierre; Réglier, Marius; Simaan, A Jalila; Tron, Thierry

    2013-05-20

    A novel tetranuclear copper(II) complex (1) was synthesized from the self-assembly of copper(II) perchlorate and the ligand N-benzyl-1-(2-pyridyl)methaneimine (L(1)). Single-crystal X-ray diffraction studies revealed that complex 1 consists of a Cu4(OH)4 cubane core, where the four copper(II) centers are linked by μ3-hydroxo bridges. Each copper(II) ion is in a distorted square-pyramidal geometry. X-ray analysis also evidenced an unusual metal cation-π interaction between the copper ions and phenyl substituents of the ligand. Calculations based on the density functional theory method were used to quantify the strength of this metal-π interaction, which appears as an important stabilizing parameter of the cubane core, possibly acting as a driving parameter in the self-aggregation process. In contrast, using the ligand N-phenethyl-1-(2-pyridyl)methaneimine (L(2)), which only differs from L(1) by one methylene group, the same synthetic procedure led to a binuclear bis(μ-hydroxo)copper(II) complex (2) displaying intermolecular π-π interactions or, by a slight variation of the experimental conditions, to a mononuclear complex (3). These complexes were studied by X-ray diffraction techniques. The magnetic properties of complexes 1 and 2 are reported and discussed.

  4. Fluorimetric determination of copper(II) in aqueous solution using lucifer yellow CH as selective metal reagent

    Energy Technology Data Exchange (ETDEWEB)

    Mayr, T.; Wencel, D.; Werner, T. [Univ. of Regensburg (Germany) Inst. of Analytical Chemistry, Chemo- and Biosensors

    2001-09-01

    Lucifer yellow CH is shown to be a highly selective fluorescent reagent for the determination of Cu(II) in the {mu}g L{sup -1} concentration range. The fluorophore is statically quenched by Cu(II); the carbohydrazide group was assigned as the complexing part of the dye molecule. A total range of Cu(II) determination from 0.06 mg L{sup -1} (1 {mu}mol L{sup -1}) to 6.3 mg L{sup -1} (100 {mu}mol L{sup -1}) with a limit of detection of 0.019 mg L{sup -1} (0.3 {mu}mol L{sup -1}) was obtained, along with surprisingly high selectivity. There was no interference from alkaline and earth alkaline metal ions. The cross sensitivity to heavy metal ions was evaluated by the separate solution method and by competitive binding experiments. Calibration plots are shown for Cu(II) determination at different pH and the dissociation constant was determined. The application of the reagent was demonstrated by the determination of the Cu(II) content of tap water samples. (orig.)

  5. Efficiency of Aluminum and Iron Electrodes for the Removal of Heavy Metals [(Ni (II), Pb (II), Cd (II)] by Electrocoagulation Method

    Energy Technology Data Exchange (ETDEWEB)

    Khosa, Muhammad Kaleem; Jamal, Muhammad Asghar; Hussain, Amira; Muneer, Majid; Zia, Khalid Mahmood [Government College Univ., Faisalabad (Pakistan); Hafeez, Samia [Bahaud-din-Zakariya Univ., Multan (Pakistan)

    2013-06-15

    Electrocoagulation (EC) technique is applied for the treatment of wastewater containing heavy metals ions such as nickel (Ni), lead (Pb) and cadmium (Cd) by using sacrificial anodes corrode to release active coagulant flocs usually aluminium or iron cations into the solution. During electrolytic reactions hydrogen gas evolve at the cathode. All the experiments were carried out in Batch mode. The tank was filled with synthetic wastewater containing heavy metals and efficiency of electrocoagulation in combination with aluminum and iron electrodes were investigated for removal of such metals. Several parameters, such as contact time, pH, electro-coagulant concentration, and current density were optimized to achieve maximum removal efficiency (%). The concentrations of heavy metals were determined by using Atomic Absorption Spectroscopy (AAS). It is found that the electro-coagulation process has potential to be utilized for the cost-effective removal of heavy metals from wastewater specially using iron electrodes in terms of high removal efficiencies and operating cost.

  6. Efficiency of Aluminum and Iron Electrodes for the Removal of Heavy Metals [(Ni (II), Pb (II), Cd (II)] by Electrocoagulation Method

    International Nuclear Information System (INIS)

    Khosa, Muhammad Kaleem; Jamal, Muhammad Asghar; Hussain, Amira; Muneer, Majid; Zia, Khalid Mahmood; Hafeez, Samia

    2013-01-01

    Electrocoagulation (EC) technique is applied for the treatment of wastewater containing heavy metals ions such as nickel (Ni), lead (Pb) and cadmium (Cd) by using sacrificial anodes corrode to release active coagulant flocs usually aluminium or iron cations into the solution. During electrolytic reactions hydrogen gas evolve at the cathode. All the experiments were carried out in Batch mode. The tank was filled with synthetic wastewater containing heavy metals and efficiency of electrocoagulation in combination with aluminum and iron electrodes were investigated for removal of such metals. Several parameters, such as contact time, pH, electro-coagulant concentration, and current density were optimized to achieve maximum removal efficiency (%). The concentrations of heavy metals were determined by using Atomic Absorption Spectroscopy (AAS). It is found that the electro-coagulation process has potential to be utilized for the cost-effective removal of heavy metals from wastewater specially using iron electrodes in terms of high removal efficiencies and operating cost

  7. Biological low pH Mn(II) oxidation in a manganese deposit influenced by metal-rich groundwater

    Science.gov (United States)

    Bohu, Tsing; Akob, Denise M.; Abratis, Michael; Lazar, Cassandre S.; Küsel, Kirsten

    2016-01-01

    The mechanisms, key organisms, and geochemical significance of biological low-pH Mn(II) oxidation are largely unexplored. Here, we investigated the structure of indigenous Mn(II)-oxidizing microbial communities in a secondary subsurface Mn oxide deposit influenced by acidic (pH 4.8) metal-rich groundwater in a former uranium mining area. Microbial diversity was highest in the Mn deposit compared to the adjacent soil layers and included the majority of known Mn(II)-oxidizing bacteria (MOB) and two genera of known Mn(II)-oxidizing fungi (MOF). Electron X-ray microanalysis showed that romanechite [(Ba,H2O)2(Mn4+,Mn3+)5O10] was conspicuously enriched in the deposit. Canonical correspondence analysis revealed that certain fungal, bacterial, and archaeal groups were firmly associated with the autochthonous Mn oxides. Eight MOB within the Proteobacteria, Actinobacteria, and Bacteroidetes and one MOF strain belonging to Ascomycota were isolated at pH 5.5 or 7.2 from the acidic Mn deposit. Soil-groundwater microcosms demonstrated 2.5-fold-faster Mn(II) depletion in the Mn deposit than adjacent soil layers. No depletion was observed in the abiotic controls, suggesting that biological contribution is the main driver for Mn(II) oxidation at low pH. The composition and species specificity of the native low-pH Mn(II) oxidizers were highly adapted to in situ conditions, and these organisms may play a central role in the fundamental biogeochemical processes (e.g., metal natural attenuation) occurring in the acidic, oligotrophic, and metalliferous subsoil ecosystems.

  8. Flame atomic absorption spectrometric determination of heavy metals in aqueous solution and surface water preceded by co-precipitation procedure with copper(II) 8-hydroxyquinoline

    Science.gov (United States)

    Ipeaiyeda, Ayodele Rotimi; Ayoade, Abisayo Ruth

    2017-12-01

    Co-precipitation procedure has widely been employed for preconcentration and separation of metal ions from the matrices of environmental samples. This is simply due to its simplicity, low consumption of separating solvent and short duration for analysis. Various organic ligands have been used for this purpose. However, there is dearth of information on the application of 8-hydroxyquinoline (8-HQ) as ligand and Cu(II) as carrier element. The use of Cu(II) is desirable because there is no contamination and background adsorption interference. Therefore, the objective of this study was to use 8-HQ in the presence of Cu(II) for coprecipitation of Cd(II), Co(II), Cr(III), Ni(II) and Pb(II) from standard solutions and surface water prior to their determinations by flame atomic absorption spectrometry (FAAS). The effects of pH, sample volume, amount of 8-HQ and Cu(II) and interfering ions on the recoveries of metal ions from standard solutions were monitored using FAAS. The water samples were treated with 8-HQ under the optimum experimental conditions and metal concentrations were determined by FAAS. The metal concentrations in water samples not treated with 8-HQ were also determined. The optimum recovery values for metal ions were higher than 85.0%. The concentrations (mg/L) of Co(II), Ni(II), Cr(III), and Pb(II) in water samples treated with 8-HQ were 0.014 ± 0.002, 0.03 ± 0.01, 0.04 ± 0.02 and 0.05 ± 0.02, respectively. These concentrations and those obtained without coprecipitation technique were significantly different. Coprecipitation procedure using 8-HQ as ligand and Cu(II) as carrier element enhanced the preconcentration and separation of metal ions from the matrix of water sample.

  9. Binding selectivity of vitamin K3 based chemosensors towards nickel(II) and copper(II) metal ions

    Science.gov (United States)

    Patil, Amit; Lande, Dipali N.; Nalkar, Archana; Gejji, Shridhar P.; Chakrovorty, Debamitra; Gonnade, Rajesh; Moniz, Tânia; Rangel, Maria; Pereira, Eulália; Salunke-Gawali, Sunita

    2017-09-01

    The vitamin K3 derivatives 2-methyl-3-[(pyridin-2-ylmethyl)-amino]-1,4-naphthoquinone (M-1), 2-methyl-3-[(pyridin-2-ylethyl)-amino]-1,4-naphthoquinone (M-2), 2-methyl-3-((2-(thiophen-2-yl)methyl)amino)naphthalene-1,4-dione (M-3) and 2-methyl-3-((2-(thiophen-2-yl)ethyl)amino)naphthalene-1,4-dione (M-4) have been synthesized, characterized and studied for their chemosensor abilities towards transition metal ions. Crystal structures of M-1 to M-4 revealed a variety of Nsbnd H⋯O, Csbnd H⋯O, Csbnd H⋯π and π⋯π interactions. Minor variations in such interactions by chemical stimuli such as metal ions, results in change in color that can be visualized by naked eyes. It has been shown that electronic structure and 1H NMR, vibrational as well as electronic spectra from the density functional theory agree well with the experiments. The metal ion binding in ethanol, ethanol-water and in mild base triethylamine brings forth recognizing ability of M-1 toward Ni2+ whereas M-2 exhibits large sensing ability for Cu2+ ion. Interestingly M-1 display varying metal ion binding specificity in different solvents with the association constant in ethanol being 11,786 M-1 for Ni2+ compared to 9462 M-1 for the Cu2+. A reversal in preferential binding of M-2 with the respective association constants being 4190 M-1 and 6370 M-1 is discernible.

  10. Preliminary screening of Ni(II metal tolerance and dye-decolorizing by Nocardiopsis sp. SD8

    Directory of Open Access Journals (Sweden)

    Ramasamy Thangaraj

    2016-04-01

    Full Text Available Objective: To reveal the screening of metal tolerance and dye-decolorizing of Nocardiopsis sp. Methods: NiSO4 and Congo red dye were used for evaluating the metal tolerance and dyedecolorizing of the randomly selected actinobacterial isolates. Results: Nocardiopsis sp. SD8 showed a better efficiency in Ni(II tolerance, though a longer lag phase was observed for this microorganism grown for 7 days in integrated mismatch negativity. Interestingly, we also found that Nocardiopsis sp. SD8 had dye-decolorizing, hemolytic, lipase and protease activity. Conclusions: The present results revealed the bioremediation of metal resistant and diverse properties of Nocardiopsis sp. SD8 and further investigations are needed to extract and identify the potent molecule.

  11. Hydride Reactivity of Ni-II-X-Ni-II Entities : Mixed-Valent Hydrido Complexes and Reversible Metal Reduction

    NARCIS (Netherlands)

    Gehring, Henrike; Metzinger, Ramona; Herwig, Christian; Intemann, Julia; Harder, Sjoerd; Limberg, Christian

    After the lithiation of PYR-H2 (PYR2-=[{NC(Me)C(H)C(Me)NC6H3(iPr)2}2(C5H3N)]2-), which is the precursor of an expanded beta-diketiminato ligand system with two binding pockets, its reaction with [NiBr2(dme)] led to a dinuclear nickel(II)bromide complex, [(PYR)Ni(mu-Br)NiBr] (1). The bridging bromide

  12. Patterns of metal composition and biological condition and their association in male common carp across an environmental contaminant gradient in Lake Mead National Recreation Area, Nevada and Arizona, USA

    Science.gov (United States)

    Patino, R.; Rosen, Michael R.; Orsak, E.L.; Goodbred, S.L.; May, T.W.; Alvarez, David; Echols, K.R.; Wieser, C.M.; Ruessler, S.; Torres, L.

    2012-01-01

    There is a contaminant gradient in Lake Mead National Recreation Area (LMNRA) that is partly driven by municipal and industrial runoff and wastewater inputs via Las Vegas Wash (LVW). Adult male common carp (Cyprinus carpio; 10 fish/site) were collected from LVW, Las Vegas Bay (receiving LVW flow), Overton Arm (OA, upstream reference), and Willow Beach (WB, downstream) in March 2008. Discriminant function analysis was used to describe differences in metal concentrations and biological condition of fish collected from the four study sites, and canonical correlation analysis was used to evaluate the association between metal and biological traits. Metal concentrations were determined in whole-body extracts. Of 63 metals screened, those initially used in the statistical analysis were Ag, As, Ba, Cd, Co, Fe, Hg, Pb, Se, Zn. Biological variables analyzed included total length (TL), Fulton's condition factor, gonadosomatic index (GSI), hematocrit (Hct), and plasma estradiol-17?? and 11-ketotestosterone (11kt) concentrations. Analysis of metal composition and biological condition both yielded strong discrimination of fish by site (respective canonical model, p< 0.0001). Compared to OA, pairwise Mahalanobis distances between group means were WB < LVB < LVW for metal concentrations and LVB < WB < LVW for biological traits. Respective primary drivers for these separations were Ag, As, Ba, Hg, Pb, Se and Zn; and TL, GSI, 11kt, and Hct. Canonical correlation analysis using the latter variable sets showed they are significantly associated (p<0.0003); with As, Ba, Hg, and Zn, and TL, 11kt, and Hct being the primary contributors to the association. In conclusion, male carp collected along a contaminant gradient in LMNRA have distinct, collection site-dependent metal and morpho-physiological profiles that are significantly associated with each other. These associations suggest that fish health and reproductive condition (as measured by the biological variables evaluated in this

  13. Zn(II)- and Cu(II)-induced non-fibrillar aggregates of amyloid-beta (1-42) peptide are transformed to amyloid fibrils, both spontaneously and under the influence of metal chelators.

    Science.gov (United States)

    Tõugu, Vello; Karafin, Ann; Zovo, Kairit; Chung, Roger S; Howells, Claire; West, Adrian K; Palumaa, Peep

    2009-09-01

    Aggregation of amyloid-beta (Abeta) peptides is a central phenomenon in Alzheimer's disease. Zn(II) and Cu(II) have profound effects on Abeta aggregation; however, their impact on amyloidogenesis is unclear. Here we show that Zn(II) and Cu(II) inhibit Abeta(42) fibrillization and initiate formation of non-fibrillar Abeta(42) aggregates, and that the inhibitory effect of Zn(II) (IC(50) = 1.8 micromol/L) is three times stronger than that of Cu(II). Medium and high-affinity metal chelators including metallothioneins prevented metal-induced Abeta(42) aggregation. Moreover, their addition to preformed aggregates initiated fast Abeta(42) fibrillization. Upon prolonged incubation the metal-induced aggregates also transformed spontaneously into fibrils, that appear to represent the most stable state of Abeta(42). H13A and H14A mutations in Abeta(42) reduced the inhibitory effect of metal ions, whereas an H6A mutation had no significant impact. We suggest that metal binding by H13 and H14 prevents the formation of a cross-beta core structure within region 10-23 of the amyloid fibril. Cu(II)-Abeta(42) aggregates were neurotoxic to neurons in vitro only in the presence of ascorbate, whereas monomers and Zn(II)-Abeta(42) aggregates were non-toxic. Disturbed metal homeostasis in the vicinity of zinc-enriched neurons might pre-dispose formation of metal-induced Abeta aggregates, subsequent fibrillization of which can lead to amyloid formation. The molecular background underlying metal-chelating therapies for Alzheimer's disease is discussed in this light.

  14. New fluorescent azo-Schiff base Cu(II) and Zn(II) metal chelates; spectral, structural, electrochemical, photoluminescence and computational studies

    Science.gov (United States)

    Purtas, Fatih; Sayin, Koray; Ceyhan, Gokhan; Kose, Muhammet; Kurtoglu, Mukerrem

    2017-06-01

    A new Schiff base containing azo chromophore group obtained by condensation of 2-hydroxy-4-[(E)-phenyldiazenyl]benzaldehyde with 3,4-dimethylaniline (HL) are used for the syntheses of new copper(II) and zinc(II) chelates, [Cu(L)2], and [Zn(L)2], and characterized by physico-chemical and spectroscopic methods such as 1H and 13C NMR, IR, UV.-Vis. and elemental analyses. The solid state structure of the ligand was characterized by single crystal X-ray diffraction study. X-ray diffraction data was then used to calculate the harmonic oscillator model of aromaticity (HOMA) indexes for the rings so as to investigate of enol-imine and keto-amine tautomeric forms in the solid state. The phenol ring C10-C15 shows a considerable deviation from the aromaticity with HOMA value of 0.837 suggesting the shift towards the keto-amine tautomeric form in the solid state. The analytical data show that the metal to ligand ratio in the chelates was found to be 1:2. Theoretical calculations of the possible isomers of the ligand and two metal complexes are performed by using B3LYP method. Electrochemical and photoluminescence properties of the synthesized azo-Schiff bases were also investigated.

  15. The Lithium-, r- and s-Enhanced Metal-Poor Giant HK-II 17435-00532

    International Nuclear Information System (INIS)

    Roederer, Ian U.; Prieto, Carlos Allende; Sneden, Christopher; Frebel, Anna; Shetrone, Matthew; Rhee, Jaehyon; Gallino, Roberto; Bisterzo, Sara; Beers, Timothy C.; Cowan, John J.

    2008-01-01

    We present the first detailed abundance analysis of the metal-poor giant HK-II 17435-00532. This star was observed as part of the University of Texas Long-Term Chemical Abundances of Stars in the Halo (CASH) Project. A spectrum was obtained with the High Resolution Spectrograph (HRS) on the Hobby-Eberly Telescope with a resolving power of R∼15000. Our analysis reveals that this star may be located on the red giant branch, red horizontal branch, or early asymptotic giant branch. We find that this metal-poor ([Fe/H] = -2.2) star has an unusually high lithium abundance (logε(Li) = +2.1), mild carbon ([C/Fe] = +0.7) and sodium ([Na/Fe] = +0.6) enhancement, as well as enhancement of both s-process ([Ba/Fe] = +0.8) and r-process ([Eu/Fe] = +0.5) material. The high Li abundance can be explained by self-enrichment through extra mixing mechanisms that connect the convective envelope with the outer regions of the H-burning shell. If so, HK-II 17435-00532 is the most metal-poor starin which this short-lived phase of Li enrichment has been observed. The r- and s-process material was not produced in this star but was either present in the gas from which HK-II 17435-00532 formed or was transferred to it from a more massive binary companion. Despite the current non-detection of radial velocity variations (over a time span of ∼180 days), it is possible that HK-II 17435-00532 is in a long-period binary system, similar to other stars with both r and s enrichment

  16. Influence of group II metals on Radium-226 concentration ratios in the native green plum (Buchanania obovata) from the Alligator Rivers Region, Northern Territory, Australia

    International Nuclear Information System (INIS)

    Medley, Peter; Bollhöfer, Andreas

    2016-01-01

    In this study, uptake of Ra from soil, and the influence of group II metals on Ra uptake, into the stones and edible flesh of the fruit of the wild green plum, Buchanania obovata, was investigated. Selective extraction of the exchangeable fraction of the soil samples was undertaken but was not shown to more reliably predict Ra uptake than total soil Ra activity concentration. Comparison of the group II metal to Ca ratios (i.e. Sr/Ca, Ba/Ca, Ra/Ca) in the flesh with exchangeable Ca shows that Ca outcompetes group II metals for root uptake and that the uptake pathway discriminated against group II metals relative to ionic radius, with uptake of Ca > Sr > Ba >> Ra. Flesh and stone analysis showed that movement of group II metals to these components of the plant, after root uptake, was strongly related. This supports the hypothesis that Sr, Ba and Ra are being taken up as analogue elements, and follow the same uptake and translocation pathways, with Ca. Comparison with previously reported data from a native passion fruit supports the use of total soil CRs on natural, undisturbed sites. As exchangeable CRs for Ra reach a saturation value it may be possible to make more precise predictions using selective extraction techniques for contaminated or disturbed sites. - Highlights: • We studied uptake of Ra-226 from soil into Buchanania obovata. • The influence of group II metals (Sr, Ba and Ca) on Ra uptake was investigated. • The exchangeable Ra fraction of the soil was not a more reliable predictor of Ra uptake than total soil Ra. • Ca outcompetes group II metals Sr, Ba and Ra for root uptake. • Uptake discriminated against group II metals relative to ionic radius, with uptake of Ca > Sr > Ba >> Ra.

  17. A metal-organic framework nanocomposite made from functionalized magnetite nanoparticles and HKUST-1 (MOF-199) for preconcentration of Cd(II), Pb(II), and Ni(II)

    International Nuclear Information System (INIS)

    Ghorbani-Kalhor, Ebrahim

    2016-01-01

    The author describes the preparation of a magnetic metal organic framework of type MOF-199 containing magnetite (Fe 3 O 4 ) nanoparticles carrying covalently immobilized 4-(thiazolylazo) resorcinol (Fe 3 O 4 -TAR). This material is shown to represent a viable sorbent for separation and preconcentration of Cd(II), Pb(II), and Ni(II) ions. Box-Behnken design was applied to optimize the parameters affecting preconcentration. Following elution with 0.6 mol L −1 EDTA, the ions were quantified by FAAS. The capacity of the sorbent ranged between 185 and 210 mg g −1 . The limits of detection are 0.15, 0.40, and 0.8 ng mL −1 for Cd(II), Ni(II), and Pb(II) ions, respectively. The relative standard deviations are <8.5 %. The method was successfully applied to the rapid extraction of trace amounts of these ions from sea food and agri food. (author)

  18. An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. II. Application—Effect of quantum confinement and homogeneous strain on Cu conductance

    Science.gov (United States)

    Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Charles, James; Klimeck, Gerhard

    2014-03-01

    The Semi-Empirical tight binding model developed in Part I Hegde et al. [J. Appl. Phys. 115, 123703 (2014)] is applied to metal transport problems of current relevance in Part II. A systematic study of the effect of quantum confinement, transport orientation, and homogeneous strain on electronic transport properties of Cu is carried out. It is found that quantum confinement from bulk to nanowire boundary conditions leads to significant anisotropy in conductance of Cu along different transport orientations. Compressive homogeneous strain is found to reduce resistivity by increasing the density of conducting modes in Cu. The [110] transport orientation in Cu nanowires is found to be the most favorable for mitigating conductivity degradation since it shows least reduction in conductance with confinement and responds most favorably to compressive strain.

  19. An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. II. Application—Effect of quantum confinement and homogeneous strain on Cu conductance

    International Nuclear Information System (INIS)

    Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Charles, James; Klimeck, Gerhard

    2014-01-01

    The Semi-Empirical tight binding model developed in Part I Hegde et al. [J. Appl. Phys. 115, 123703 (2014)] is applied to metal transport problems of current relevance in Part II. A systematic study of the effect of quantum confinement, transport orientation, and homogeneous strain on electronic transport properties of Cu is carried out. It is found that quantum confinement from bulk to nanowire boundary conditions leads to significant anisotropy in conductance of Cu along different transport orientations. Compressive homogeneous strain is found to reduce resistivity by increasing the density of conducting modes in Cu. The [110] transport orientation in Cu nanowires is found to be the most favorable for mitigating conductivity degradation since it shows least reduction in conductance with confinement and responds most favorably to compressive strain

  20. An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. II. Application—Effect of quantum confinement and homogeneous strain on Cu conductance

    Energy Technology Data Exchange (ETDEWEB)

    Hegde, Ganesh, E-mail: ghegde@purdue.edu; Povolotskyi, Michael; Kubis, Tillmann; Charles, James; Klimeck, Gerhard, E-mail: gekco@purdue.edu [Network for Computational Nanotechnology (NCN), Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2014-03-28

    The Semi-Empirical tight binding model developed in Part I Hegde et al. [J. Appl. Phys. 115, 123703 (2014)] is applied to metal transport problems of current relevance in Part II. A systematic study of the effect of quantum confinement, transport orientation, and homogeneous strain on electronic transport properties of Cu is carried out. It is found that quantum confinement from bulk to nanowire boundary conditions leads to significant anisotropy in conductance of Cu along different transport orientations. Compressive homogeneous strain is found to reduce resistivity by increasing the density of conducting modes in Cu. The [110] transport orientation in Cu nanowires is found to be the most favorable for mitigating conductivity degradation since it shows least reduction in conductance with confinement and responds most favorably to compressive strain.

  1. Optical characterization and blu-ray recording properties of metal(II) azo barbituric acid complex films

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.Y. [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)], E-mail: xyli@siom.ac.cn; Wu, Y.Q. [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Key Lab of Functional Inorganic Material Chemistry (Heilongjiang University), Ministry of Education, Haerbin 150080 (China)], E-mail: yqwu@siom.ac.cn; Gu, D.D.; Gan, F.X. [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2009-02-25

    Smooth thin films of nickel(II), cobalt(II) and zinc(II) complexes with azo barbituric acid were prepared by the spin-coating method. Absorption spectra of the thin films on K9 glass substrates in 300-700 nm wavelength region were measured. Optical constants (complex refractive index N = n + ik) of the thin films prepared on single-crystal silicon substrates in 275-695 nm wavelength region were investigated on rotating analyzer-polarizer type of scanning ellipsometer, and dielectric constant {epsilon} ({epsilon} = {epsilon}{sub 1} + i{epsilon}{sub 2}) as well as absorption coefficient {alpha} of thin films were calculated at 405 nm. In addition, static optical recording properties of the cobalt(II) complex thin film with an Ag reflective layer was carried out using a 406.7 nm blue-violet laser and a high numerical aperture (NA) of 0.90. Clear recording marks with high reflectivity contrast (>60%) at proper laser power and pulse width were obtained, and the size of recording mark was as small as 250 nm. The results indicate that these metal(II) complexes are promising organic recording medium for the blu-ray optical storage system.

  2. Adsorption of Azo-Dye Orange II from Aqueous Solutions Using a Metal-Organic Framework Material: Iron- Benzenetricarboxylate

    Science.gov (United States)

    Rojas García, Elizabeth; López Medina, Ricardo; May Lozano, Marcos; Hernández Pérez, Isaías; Valero, Maria J.; Maubert Franco, Ana M.

    2014-01-01

    A Metal-Organic Framework (MOF), iron-benzenetricarboxylate (Fe(BTC)), has been studied for the adsorptive removal of azo-dye Orange II from aqueous solutions, where the effect of various parameters was tested and isotherm and kinetic models were suggested. The adsorption capacities of Fe(BTC) were much higher than those of an activated carbon. The experimental data can be best described by the Langmuir isotherm model (R2 > 0.997) and revealed the ability of Fe(BTC) to adsorb 435 mg of Orange II per gram of adsorbent at the optimal conditions. The kinetics of Orange II adsorption followed a pseudo-second-order kinetic model, indicating the coexistence of physisorption and chemisorption, with intra-particle diffusion being the rate controlling step. The thermodynamic study revealed that the adsorption of Orange II was feasible, spontaneous and exothermic process (−25.53 kJ·mol−1). The high recovery of the dye showed that Fe(BTC) can be employed as an effective and reusable adsorbent for the removal of Orange II from aqueous solutions and showed the economic interest of this adsorbent material for environmental purposes. PMID:28788289

  3. Adsorption of Azo-Dye Orange II from Aqueous Solutions Using a Metal-Organic Framework Material: Iron- Benzenetricarboxylate

    Directory of Open Access Journals (Sweden)

    Elizabeth Rojas García

    2014-12-01

    Full Text Available A Metal-Organic Framework (MOF, iron-benzenetricarboxylate (Fe(BTC, has been studied for the adsorptive removal of azo-dye Orange II from aqueous solutions, where the effect of various parameters was tested and isotherm and kinetic models were suggested. The adsorption capacities of Fe(BTC were much higher than those of an activated carbon. The experimental data can be best described by the Langmuir isotherm model (R2 > 0.997 and revealed the ability of Fe(BTC to adsorb 435 mg of Orange II per gram of adsorbent at the optimal conditions. The kinetics of Orange II adsorption followed a pseudo-second-order kinetic model, indicating the coexistence of physisorption and chemisorption, with intra-particle diffusion being the rate controlling step. The thermodynamic study revealed that the adsorption of Orange II was feasible, spontaneous and exothermic process (−25.53 kJ·mol−1. The high recovery of the dye showed that Fe(BTC can be employed as an effective and reusable adsorbent for the removal of Orange II from aqueous solutions and showed the economic interest of this adsorbent material for environmental purposes.

  4. A new photoactive Ru(II)tris(2,2'-bipyridine) templated Zn(II) benzene-1,4-dicarboxylate metal organic framework: structure and photophysical properties.

    Science.gov (United States)

    Whittington, Christi L; Wojtas, Lukasz; Gao, Wen-Yang; Ma, Shengqian; Larsen, Randy W

    2015-03-28

    It has now been demonstrated that Ru(ii)tris(2,2'-bipyridine) (RuBpy) can be utilized to template the formation of new metal organic framework (MOF) materials containing crystallographically resolved RuBpy clusters with unique photophysical properties. Two such materials, RWLC-1 and RWLC-2, have now been reported from our laboratory and are composed of RuBpy encapsulated in MOFs composed of Zn(ii) ions and 1,3,5-tris(4-carboxyphenyl)benzene ligands (C. L. Whittington, L. Wojtas and R. W. Larsen, Inorg. Chem., 2014, 53, 160-166). Here, a third RuBpy templated photoactive MOF is described (RWLC-3) that is derived from the reaction between Zn(ii) ions and 1,4-dicarboxybenzene in the presence of RuBpy. Single Crystal X-ray diffraction studies determined the position of RuBpy cations within the crystal lattice. The RWLC-3 structure is described as a 2-fold interpenetrated pillared honeycomb network (bnb) containing crystallographically resolved RuBpy clusters. The two bnb networks are weakly interconnected. The encapsulated RuBpy exhibits two emission decay lifetimes (τ-fast = 120 ns, τ-slow = 453 ns) and a bathochromic shift in the steady state emission spectrum relative to RuBpy in ethanol.

  5. Multifunctional Metal/Polymer Composite Fiber for Space Applications, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Small Business Innovation Research Phase II Program, Syscom Technology, Inc. will implement an integrated processing scheme to fabricate a conductive...

  6. Metal-poor dwarf galaxies in the SIGRID galaxy sample. I. H II region observations and chemical abundances

    International Nuclear Information System (INIS)

    Nicholls, David C.; Dopita, Michael A.; Sutherland, Ralph S.; Jerjen, Helmut; Kewley, Lisa J.; Basurah, Hassan

    2014-01-01

    In this paper we present the results of observations of 17 H II regions in thirteen galaxies from the SIGRID sample of isolated gas-rich irregular dwarf galaxies. The spectra of all but one of the galaxies exhibit the auroral [O III] 4363 Å line, from which we calculate the electron temperature, T e , and gas-phase oxygen abundance. Five of the objects are blue compact dwarf galaxies, of which four have not previously been analyzed spectroscopically. We include one unusual galaxy which exhibits no evidence of the [N II] λλ 6548,6584 Å lines, suggesting a particularly low metallicity (< Z ☉ /30). We compare the electron temperature based abundances with those derived using eight of the new strong-line diagnostics presented by Dopita et al. Using a method derived from first principles for calculating total oxygen abundance, we show that the discrepancy between the T e -based and strong-line gas-phase abundances have now been reduced to within ∼0.07 dex. The chemical abundances are consistent with what is expected from the luminosity-metallicity relation. We derive estimates of the electron densities and find them to be between ∼5 and ∼100 cm –3 . We find no evidence for a nitrogen plateau for objects in this sample with metallicities 0.5 > Z ☉ > 0.15.

  7. Metal-poor dwarf galaxies in the SIGRID galaxy sample. I. H II region observations and chemical abundances

    Energy Technology Data Exchange (ETDEWEB)

    Nicholls, David C.; Dopita, Michael A.; Sutherland, Ralph S.; Jerjen, Helmut; Kewley, Lisa J. [Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston ACT 2611 (Australia); Basurah, Hassan, E-mail: David.Nicholls@anu.edu.au [Astronomy Department, King Abdulaziz University, P.O. Box 80203 Jeddah (Saudi Arabia)

    2014-05-10

    In this paper we present the results of observations of 17 H II regions in thirteen galaxies from the SIGRID sample of isolated gas-rich irregular dwarf galaxies. The spectra of all but one of the galaxies exhibit the auroral [O III] 4363 Å line, from which we calculate the electron temperature, T{sub e} , and gas-phase oxygen abundance. Five of the objects are blue compact dwarf galaxies, of which four have not previously been analyzed spectroscopically. We include one unusual galaxy which exhibits no evidence of the [N II] λλ 6548,6584 Å lines, suggesting a particularly low metallicity (< Z {sub ☉}/30). We compare the electron temperature based abundances with those derived using eight of the new strong-line diagnostics presented by Dopita et al. Using a method derived from first principles for calculating total oxygen abundance, we show that the discrepancy between the T{sub e} -based and strong-line gas-phase abundances have now been reduced to within ∼0.07 dex. The chemical abundances are consistent with what is expected from the luminosity-metallicity relation. We derive estimates of the electron densities and find them to be between ∼5 and ∼100 cm{sup –3}. We find no evidence for a nitrogen plateau for objects in this sample with metallicities 0.5 > Z {sub ☉} > 0.15.

  8. Nearby supernova host galaxies from the CALIFA survey. II. Supernova environmental metallicity

    NARCIS (Netherlands)

    Galbany, L.; Stanishev, V.; Mourão, A. M.; Rodrigues, M.; Flores, H.; Walcher, C. J.; Sánchez, S. F.; García-Benito, R.; Mast, D.; Badenes, C.; González Delgado, R. M.; Kehrig, C.; Lyubenova, M.; Marino, R. A.; Mollá, M.; Meidt, S.; Pérez, E.; van de Ven, G.; Vílchez, J. M.

    2016-01-01

    The metallicity of a supernova progenitor, together with its mass, is one of the main parameters that can rule the progenitor's fate. We present the second study of nearby supernova (SN) host galaxies (0.005 ⊙) > 10 dex) by targeted searches. We neither found evidence that the metallicity at the SN

  9. Development of metal fuel and study of construction materials (I-IV), Part II

    International Nuclear Information System (INIS)

    Mihajlovic, A.

    1965-11-01

    The studies were devoted to problems related to application of metal uranium as fuel in heavy water reactors. Influence of thermal treatment on material texture and recrystallization of cast uranium was investigated. Structural changes of uranium alloys with molybdenum and niobium were tested during different heat treatments. A review of the possibilities for using metal uranium fuel in heavy water reactors is included

  10. Evaporated metal films as indicators of atmospheric pollution. II. Resistance measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lodge, Jr, J P; Frank, E R

    1962-01-01

    There appears to be a direct relationship between gross atmospheric features associated with the accumulation of substances in air that are corrosive to metals and the rate of resistance change of thin metallic films. This behavior is the most striking in aluminum. The suggested apparatus provides an inexpensive and rapid method determining total atmospheric corrosiveness. 1 reference, 10 figures.

  11. Pb(II) and Hg(II) binding to $\\textit{de novo}$ designed proteins studied by $^{204m}$Pb- and $^{199m}$Hg-Perturbed Angular Correlation of $\\gamma$-rays (PAC) spectroscopy : Clues to heavy metal toxicity

    CERN Multimedia

    2002-01-01

    $\\textit{De novo}$ design of proteins combined with PAC spectroscopy offers a unique and powerful approach to the study of fundamental chemistry of heavy metal-protein interactions, and thus of the mechanisms underlying heavy metal toxicity. In this project we focus on Pb(II) and Hg(II) binding to designed three stranded coiled coil proteins with one or two binding sites, mimicking a variety of naturally occurring thiolate-rich metal ion binding sites in proteins. The $^{204m}$Pb- and $^{199m}$Hg-PAC experiments will complement data already recorded with EXAFS, NMR, UV-Vis and CD spectroscopies.

  12. Heavy metal pollution among autoworkers. II. Cadmium, chromium, copper, manganese, and nickel

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, J.; Rastogi, S.C.

    1977-08-01

    Garages and auto-repair workshops may be polluted with other heavy metals besides lead. Blood of autoworkers with high lead content was analyzed for cadmium, chromium, copper, manganese, nickel, ALAD activity and carboxyhaemoglobin level. Cadmium and copper levels in blood of autoworkers were comparable with those of the control subjects while chromium and nickel levels were significantly higher (P < 0.01 for both metals), and scattered raised values of manganese were found. There was no significant mutual correlation between levels of various heavy metals determined in whole blood. High copper levels were slightly related to decreasing ALAD activity (P < 0.1). Nineteen percent of autoworkers were found to have an abnormally high blood level of carboxyhemoglobin. The amount of particulate heavy metal in autoworkshop air was not related to biochemical abnormalities found in the autoworkers. Various sources of pollution of these heavy metals in autoworkshops are discussed.

  13. GLOBULAR CLUSTER ABUNDANCES FROM HIGH-RESOLUTION, INTEGRATED-LIGHT SPECTROSCOPY. II. EXPANDING THE METALLICITY RANGE FOR OLD CLUSTERS AND UPDATED ANALYSIS TECHNIQUES

    Energy Technology Data Exchange (ETDEWEB)

    Colucci, Janet E.; Bernstein, Rebecca A.; McWilliam, Andrew [The Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101 (United States)

    2017-01-10

    We present abundances of globular clusters (GCs) in the Milky Way and Fornax from integrated-light (IL) spectra. Our goal is to evaluate the consistency of the IL analysis relative to standard abundance analysis for individual stars in those same clusters. This sample includes an updated analysis of seven clusters from our previous publications and results for five new clusters that expand the metallicity range over which our technique has been tested. We find that the [Fe/H] measured from IL spectra agrees to ∼0.1 dex for GCs with metallicities as high as [Fe/H] = −0.3, but the abundances measured for more metal-rich clusters may be underestimated. In addition we systematically evaluate the accuracy of abundance ratios, [X/Fe], for Na i, Mg i, Al i, Si i, Ca i, Ti i, Ti ii, Sc ii, V i, Cr i, Mn i, Co i, Ni i, Cu i, Y ii, Zr i, Ba ii, La ii, Nd ii, and Eu ii. The elements for which the IL analysis gives results that are most similar to analysis of individual stellar spectra are Fe i, Ca i, Si i, Ni i, and Ba ii. The elements that show the greatest differences include Mg i and Zr i. Some elements show good agreement only over a limited range in metallicity. More stellar abundance data in these clusters would enable more complete evaluation of the IL results for other important elements.

  14. Synthesis, characterisation and catalytic activity of 4, 5-imidazoledicarboxylate ligated Co(II) and Cd(II) metal-organic coordination complexes

    Science.gov (United States)

    Gangu, Kranthi Kumar; Maddila, Suresh; Mukkamala, Saratchandra Babu; Jonnalagadda, Sreekantha B.

    2017-09-01

    Two mono nuclear coordination complexes, namely, [Co(4,5-Imdc)2 (H2O)2] (1) and [Cd(4,5-Imdc)2(H2O)3]·H2O (2) were constructed using Co(II) and Cd(II) metal salts with 4,5-Imidazoledicarboxylic acid (4,5-Imdc) as organic ligand. Both 1, 2 were structurally characterized by single crystal XRD and the results reveal that 1 belongs to P21/n space group with unit cell parameters [a = 5.0514(3) Å, b = 22.5786(9) Å, c = 6.5377(3) Å, β = 111.5°] whereas, 2 belongs to P21/c space group with unit cell parameters [a = 6.9116(1) Å, b = 17.4579(2) Å, c = 13.8941(2) Å, β = 97.7°]. While Co(II) in 1 exhibited a six coordination geometry with 4,5-Imdc and water molecules, Cd(II) ion in 2 showed a seven coordination with the same ligand and solvent. In both 1 and 2, the hydrogen bond interactions with mononuclear unit generated 3D-supramolecular structures. Both complexes exhibit solid state fluorescent emission at room temperature. The efficacy of both the complexes as heterogeneous catalysts was examined in the green synthesis of six pyrano[2,3,c]pyrazole derivatives with ethanol as solvent via one-pot reaction between four components, a mixture of aromatic aldehyde, malononitrile, hydrazine hydrate and dimethyl acetylenedicarboxylate. Both 1 and 2 have produced pyrano [2,3,c]pyrazoles in impressive yields (92-98%) at room temperature in short interval of times (<20 min), with no need for any chromatographic separations. With good stability, ease of preparation and recovery plus reusability up to six cycles, both 1 and 2 prove to be excellent environmental friendly catalysts for the value-added organic transformations using green principles.

  15. High-resolution metal gradients measured by in situ DGT/DET deployment in Black Sea sediments using an autonomous benthic lander RID G-2489-2010 RID A-4901-2009

    DEFF Research Database (Denmark)

    Fones, GR; Davison, W.; Holby, O.

    2001-01-01

    DET (Diffusive equilibration in thin films) and DGT (diffusive gradients in thin films) have been deployed in situ using an autonomous benthic lander to measure concentrations and induced fluxes of Fe and Mn (DET/DGT) and trace metals (DGT) in pore waters at millimeter spatial resolutions....... The newly developed deployment system is described, and based on these first results, its strengths and weaknesses are discussed. Deployments were made in the Western Black Sea in shelf sediments overlain by well-oxygenated water at a water depth of 77 m. Maxima of the redox-sensitive metals at 4 and 8 cm...... elements by several millimeters. Detection of this functional discrimination between Fe and Mn as regulators of trace metals would not have been possible using more conventional sampling procedures....

  16. Oligo-m-phenyleneoxalamide copper(II) mesocates as electro-switchable ferromagnetic metal-organic wires.

    Science.gov (United States)

    Pardo, Emilio; Ferrando-Soria, Jesús; Dul, Marie-Claire; Lescouëzec, Rodrigue; Journaux, Yves; Ruiz-García, Rafael; Cano, Joan; Julve, Miguel; Lloret, Francesc; Cañadillas-Delgado, Laura; Pasán, Jorge; Ruiz-Pérez, Catalina

    2010-11-15

    Double-stranded copper(II) string complexes of varying nuclearity, from di- to tetranuclear species, have been prepared by the Cu(II)-mediated self-assembly of a novel family of linear homo- and heteropolytopic ligands that contain two outer oxamato and either zero (1 b), one (2 b), or two (3 b) inner oxamidato donor groups separated by rigid 2-methyl-1,3-phenylene spacers. The X-ray crystal structures of these Cu(II) (n) complexes (n=2 (1 d), 3 (2 d), and 4 (3 d)) show a linear array of metal atoms with an overall twisted coordination geometry for both the outer CuN(2)O(2) and inner CuN(4) chromophores. Two such nonplanar all-syn bridging ligands 1 b-3 b in an anti arrangement clamp around the metal centers with alternating M and P helical chiralities to afford an overall double meso-helicate-type architecture for 1 d-3 d. Variable-temperature (2.0-300 K) magnetic susceptibility and variable-field (0-5.0 T) magnetization measurements for 1 d-3 d show the occurrence of S=nS(Cu) (n=2-4) high-spin ground states that arise from the moderate ferromagnetic coupling between the unpaired electrons of the linearly disposed Cu(II) ions (S(Cu)=1/2) through the two anti m-phenylenediamidate-type bridges (J values in the range of +15.0 to 16.8 cm(-1)). Density functional theory (DFT) calculations for 1 d-3 d evidence a sign alternation of the spin density in the meta-substituted phenylene spacers in agreement with a spin polarization exchange mechanism along the linear metal array with overall intermetallic distances between terminal metal centers in the range of 0.7-2.2 nm. Cyclic voltammetry (CV) and rotating-disk electrode (RDE) electrochemical measurements for 1 d-3 d show several reversible or quasireversible one- or two-electron steps that involve the consecutive metal-centered oxidation of the inner and outer Cu(II) ions (S(Cu)=1/2) to diamagnetic Cu(III) ones (S(Cu)=0) at relatively low formal potentials (E values in the range of

  17. Removal of Hg(II) from aqueous solution using sodium humate as heavy metal capturing agent.

    Science.gov (United States)

    Wang, Shixiang; Liu, Yong; Fan, Qin; Zhou, Anlan; Fan, Lu; Mu, Yulan

    2016-12-01

    An environmental friendly and economic natural biopolymer-sodium humate (HA-Na) was used to capture Hg(II) from aqueous solutions, and the trapped Hg(II) (HA-Na-Hg) was then removed by aluminium coagulation. The best Hg(II) capturing performance (90.60%) was observed under the following conditions: initial pH of 7.0, coagulation pH of 6.0, HA-Na dosage of 5.0 g L -1 , Al 2 (SO 4 ) 3 .18H 2 O dosage of 4.0 g L -1 , initial Hg(II) concentration of 50 mg L -1 and capturing time of 30 min. The HA-Na compositions with the molecular weight beyond 70 kDa showed the most intense affinity toward Hg(II). The results showed that the reaction equilibrium was achieved within 10 min (pH 7.0), and could be well fitted by the pseudo-second-order kinetics model. The capturing process could be well described by the Langmuir isotherm model and the maximum capturing capacity of Hg(II) was high up to 9.80 mg g -1 at 298 K (pH 7.0). The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis showed that the redox reaction between Hg(II) and HA-Na and the coordination reaction of carboxyl and hydroxy groups of HA-Na with Hg(II) were responsible for Hg(II) removal. The successive regeneration experiment showed that the capturing efficiency of humates for Hg(II) was maintained at about 51% after five capture-regeneration recycles.

  18. Alginate and Algal-Based Beads for the Sorption of Metal Cations: Cu(II and Pb(II

    Directory of Open Access Journals (Sweden)

    Shengye Wang

    2016-09-01

    Full Text Available Alginate and algal-biomass (Laminaria digitata beads were prepared by homogeneous Ca ionotropic gelation. In addition, glutaraldehyde-crosslinked poly (ethyleneimine (PEI was incorporated into algal beads. The three sorbents were characterized by scanning electron microscopy (SEM coupled with energy dispersive X-ray analysis (EDX: the sorption occurs in the whole mass of the sorbents. Sorption experiments were conducted to evaluate the impact of pH, sorption isotherms, and uptake kinetics. A special attention was paid to the effect of drying (air-drying vs. freeze-drying on the mass transfer properties. For alginate, freeze drying is required for maintaining the porosity of the hydrogel, while for algal-based sorbents the swelling of the material minimizes the impact of the drying procedure. The maximum sorption capacities observed from experiments were 415, 296 and 218 mg Pb g−1 and 112, 77 and 67 mg Cu g−1 for alginate, algal and algal/PEI beads respectively. Though the sorption capacities of algal-beads decreased slightly (compared to alginate beads, the greener and cheaper one-pot synthesis of algal beads makes this sorbent more competitive for environmental applications. PEI in algal beads decreases the sorption properties in the case of the sorption of metal cations under selected experimental conditions.

  19. Controlling the oxidation of bis-tridentate cobalt(ii) complexes having bis(2-pyridylalkyl)amines: ligand vs. metal oxidation.

    Science.gov (United States)

    Anjana, S; Donring, S; Sanjib, P; Varghese, B; Murthy, Narasimha N

    2017-08-22

    Two bis-tridentate chelated cobalt(ii) complexes, which differ in the ligand structure by a methylene group, activate molecular oxygen (O 2 ), and give different oxidation products. The O 2 reaction of [Co II (pepma) 2 ] 2+ (1) with unsymmetrical 2-(2-pyridyl)-N-(2-pyridylmethyl)ethanamine (pepma) results in ligand oxidation, to the corresponding Co(ii) imine complex [Co II (pepmi) 2 ] 2+ (2). Contrastingly, the Co(ii) complex [Co II (bpma) 2 ] 2+ (3) of similar symmetrical bis(2-pyridylmethyl)amine (bpma), undergoes metal oxidation, yielding a cobalt(iii) complex, [Co III (bpma) 2 ] 2+ (4). The reversibility of the amine to imine conversion and the stability of the Co(ii) imine complex (2) are investigated. Furthermore, the solution dynamics of Co(ii) complexes are highlighted with the help of paramagnetic 1 H-NMR spectroscopy.

  20. Simultaneous spectrophotometric determination of heavy metal ions Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) with Br-PADPA in primary reactor coolant system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-Hyeong; Yun, Jong-Il [KAIST, Daejeon (Korea, Republic of)

    2015-05-15

    The performance with integrity of nuclear power plants is highly influenced by the presence of the corrosion products. The deposition of corrosion products in the steam generator is the one of the main concerns of power plants. The quantification of corrosion products is considered of importance. In this study, we applied the spectrophotometric method to detect metal ions such as iron, cobalt, nickel, copper, and zinc, which are major elements of structural material of the plant. In particular, the chemical complexation of those divalent metal ions with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP) provides high molar absorptivity. For the simultaneous determination of metal ions, a partial least square (PLS) regression method was applied. In the present work, the complexation of Br-PADAP with divalent metal ions (iron, cobalt, nickel, copper and zinc) was studied. The PLS regression method was successfully applied for simultaneous elemental detection in multi-element systems. These results suggests that the method is very ample to detect corrosion products in nuclear power plants.

  1. A porous Cd(II) metal-organic framework with high adsorption selectivity for CO2 over CH4

    Science.gov (United States)

    Zhu, Chunlan

    2017-05-01

    Metal-organic frameworks (MOFs) have attracted a lot of attention in recent decades. We applied a semi-rigid four-carboxylic acid linker to assemble with Cd(II) ions to generate a novel microporous Cd(II) MOF material. Single crystal X-ray diffraction study reveals the different two dimension (2D) layers can be further packed together with an AB fashion by hydrogen bonds (O4sbnd H4⋯O7 = 1.863 Å) to construct a three dimension (3D) supermolecular architecture. The resulting sample can be synthesized under solvothermal reactions successfully, which exhibits high selectivity adsorption of CO2 over CH4 at room temperature. In addition, the obtained sample was characterized by thermal gravimetric analyses (TGA), Fourier-transform infrared spectra (FT-IR), elemental analysis (CHN) and powder X-ray diffraction (PXRD).

  2. Catalytic combustion of propane in a membrane reactor with separate feed of reactants—II. Operation in presence of trans-membrane pressure gradients

    NARCIS (Netherlands)

    Saracco, Guido; Veldsink, Jan Willem; Versteeg, Geert F.; Swaaij, Wim P.M. van

    1995-01-01

    This is the second communication of a series dealing with an experimental and modelling study on propane catalytic combustion in a membrane reactor with separate feed of reactants. In paper I the behaviour of the reactor in the absence of trans-membrane pressure gradients was presented and

  3. Applications of RIGAKU Dmax Rapid II micro-X-ray diffractometer in the analysis of archaeological metal objects

    Science.gov (United States)

    Mozgai, Viktória; Szabó, Máté; Bajnóczi, Bernadett; Weiszburg, Tamás G.; Fórizs, István; Mráv, Zsolt; Tóth, Mária

    2017-04-01

    During material analysis of archaeological metal objects, especially their inlays or corrosion products, not only microstructure and chemical composition, but mineralogical composition is necessary to be determined. X-ray powder diffraction (XRD) is a widely-used method to specify the mineralogical composition. However, when sampling is not or limitedly allowed due to e.g. the high value of the object, the conventional XRD analysis can hardly be used. Laboratory micro-XRD instruments provide good alternatives, like the RIGAKU Dmax Rapid II micro-X-ray diffractometer, which is a unique combination of a MicroMax-003 third generation microfocus, sealed tube X-ray generator and a curved 'image plate' detector. With this instrument it is possible to measure as small as 10 µm area in diameter on the object. Here we present case studies for the application of the micro-XRD technique in the study of archaeological metal objects. In the first case niello inlay of a Late Roman silver augur staff was analysed. Due to the high value of the object, since it is the only piece known from the Roman Empire, only non-destructive analyses were allowed. To reconstruct the preparation of the niello, SEM-EDX analysis was performed on the niello inlays to characterise their chemical composition and microstructure. Two types of niello are present: a homogeneous, silver sulphide niello (acanthite) and an inhomogeneous silver-copper sulphide niello (exsolution of acanthite and jalpaite or jalpaite and stromeyerite). The micro-X-ray diffractometer was used to verify the mineralogical composition of the niello, supposed on the base of SEM results. In the second case corrosion products of a Late Roman copper cauldron with uncertain provenance were examined, since they may hold clues about the burial conditions (pH, Eh, etc.) of the object. A layer by layer analysis was performed in cross sections of small metal samples by using electron microprobe and micro-X-ray diffractometer. The results

  4. Multifunctional, Nanostructured Metal Rubber Protective Films for Space Exploration, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — NanoSonic has developed revolutionary nanostructured, yet macroscale, multifunctional Metal RubberTM films. In support of NASA's Vision for Space Exploration, low...

  5. Metal-Mesh Optical Filter Technology for Mid IR, Far IR, and Submillimeter, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovative, high transmission band-pass filter technology proposed here is an improvement in multilayer metal-mesh filter design and manufacture for the far IR...

  6. Automated Design and Analysis Tool for CLV/CEV Composite and Metallic Structural Components, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation of the proposed effort is a unique automated process for the analysis, design, and sizing of CLV/CEV composite and metallic structures. This developed...

  7. Shock Hazard Prevention through Self-Healing Insulative Coating on SSA Metallic Bearings, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The space suit assembly (SSA) contains metallic bearings at the wrist, neck, and waist, which are exposed to space environment, and pose a potential shock hazard....

  8. and Pb(ii) by Phanerochaete chrysosporium from a binary metal ...

    African Journals Online (AJOL)

    drinie

    2001-01-01

    Jan 1, 2001 ... Kinetic studies revealed that biosorption takes place in two stages: a rapid surface adsorption, within the ... With the help of multi-metal biosorption studies, these complex ..... bioreactor for color removal from bleach effluents.

  9. Irradiance gradients

    International Nuclear Information System (INIS)

    Ward, G.J.; Heckbert, P.S.; Technische Hogeschool Delft

    1992-04-01

    A new method for improving the accuracy of a diffuse interreflection calculation is introduced in a ray tracing context. The information from a hemispherical sampling of the luminous environment is interpreted in a new way to predict the change in irradiance as a function of position and surface orientation. The additional computation involved is modest and the benefit is substantial. An improved interpolation of irradiance resulting from the gradient calculation produces smoother, more accurate renderings. This result is achieved through better utilization of ray samples rather than additional samples or alternate sampling strategies. Thus, the technique is applicable to a variety of global illumination algorithms that use hemicubes or Monte Carlo sampling techniques

  10. Infrared multiple photon dissociation spectroscopy of group I and group II metal complexes with Boc-hydroxylamine.

    Science.gov (United States)

    Dain, Ryan P; Gresham, Gary; Groenewold, Gary S; Steill, Jeffrey D; Oomens, Jos; Van Stipdonk, Michael J

    2013-08-30

    Hydroxamates are essential growth factors for some microbes, acting primarily as siderophores that solubilize iron for transport into a cell. Here we determined the intrinsic structure of 1:1 complexes between Boc-protected hydroxylamine and group I ([M(L)](+)) and group II ([M(L-H)](+)) cations, where M and L are the cation and ligand, respectively, which are convenient models for the functional unit of hydroxamate siderphores. The relevant complex ions were generated by electrospray ionization (ESI) and isolated and stored in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Infrared spectra of the isolated complexes were collected by monitoring (infrared) photodissociation yield as a function of photon energy. Experimental spectra were then compared to those predicted by density functional theory (DFT) calculations. The infrared multiple photon dissociation (IRMPD) spectra collected are in good agreement with those predicted to be lowest-energy by DFT. The spectra for the group I complexes contain six resolved absorptions that can be attributed to amide I and II type and hydroxylamine N-OH vibrations. Similar absorptions are observed for the group II cation complexes, with shifts of the amide I and amide II vibrations due to the change in structure with deprotonation of the hydroxylamine group. IRMPD spectroscopy unequivocally shows that the intrinsic binding mode for the group I cations involves the O atoms of the amide carbonyl and hydroxylamine groups of Boc-hydroxylamine. A similar binding mode is preferred for the group II cations, except that in this case the metal ion is coordinated by the O atom of the deprotonated hydroxylamine group. Copyright © 2013 John Wiley & Sons, Ltd.

  11. Synthesis, spectroscopic characterization, electrochemistry and biological evaluation of some metal (II) complexes with ONO donor ligand containing benzo[b]thiophene and coumarin moieties

    Science.gov (United States)

    Mahendra Raj, K.; Mruthyunjayaswamy, B. H. M.

    2014-09-01

    Schiff base ligand 3-chloro-N‧-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzo[b]thiophene-2-carbohydrazide and its Cu(II), Co(II), Ni(II) and Zn(II) complexes were synthesized, characterized by elemental analysis and various physico-chemical techniques like, IR, 1H NMR, ESI-mass, UV-Visible, thermogravimetry - differential thermal analysis, magnetic measurements and molar conductance. Spectral analysis indicates octahedral geometry for all the complexes. Cu(II) complex have 1:1 stoichiometry of the type [M(L)(Cl)(H2O)2], whereas Co(II), Ni(II) and Zn(II) complexes have 1:2 stoichiometric ratio of the type [M(L)2]. The bonding sites are the oxygen atom of amide carbonyl, nitrogen of azomethine function and phenolic oxygen of the Schiff base ligand via deprotonation. The thermogravimetry - differential thermal analysis studies gave evidence for the presence of coordinated water molecules in the composition of Cu(II) complex which was further supported by IR measurements. All the complexes were investigated for their electrochemical activity, but only the Cu(II) complex showed the redox property. In order to evaluate the effect of antimicrobial potency of metal ions upon chelation, ligand and its metal complexes along with their respective metal chlorides were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The results showed that the metal complexes were found to be more active than free ligand. Ligand and its complexes were screened for free radical scavenging activity by DPPH method and DNA cleavage activity using Calf-thymus DNA (Cat. No-105850).

  12. Iron metal production in silicate melts through the direct reduction of Fe/II/ by Ti/III/, Cr/II/, and Eu/II/. [in lunar basalts

    Science.gov (United States)

    Schreiber, H. D.; Balazs, G. B.; Shaffer, A. P.; Jamison, P. L.

    1982-01-01

    The production of metallic iron in silicate melts by chemical reactions of Ti(3+), Cr(2+), and Eu(2+) with Fe(2+) is demonstrated under experimental conditions in a simplified basaltic liquid. These reactions form a basis for interpreting the role of isochemical valency exchange models in explanations for the reduced nature of lunar basalts. The redox couples are individually investigated in the silicate melt to ascertain reference redox ratios that are independent of mutual interactions. These studies also provide calibrations of spectral absorptions of the Fe(2+) and Ti(2+) species in these glasses. Subsequent spectrophotometric analyses of Fe(2+) and Ti(2+) in glasses doped with both iron and titanium and of Fe(2+) in glasses doped with either iron and chromium or iron and europium ascertain the degree of mutual interactions in these dual-doped glasses.

  13. Minutes of the 28th Annual Plutonium Sample Exchange Meeting. Part II: metal sample exchange

    International Nuclear Information System (INIS)

    1984-01-01

    Contents of this publication include the following list of participating laboratories; agenda; attendees; minutes of October 25 and 26 meeting; and handout materials supplied by speakers. The handout materials cover the following: statistics and reporting; plutonium - chemical assay 100% minus impurities; americium neptunium, uranium, carbon and iron data; emission spectroscopy data; plutonium metal sample exchange; the calorimetry sample exchange; chlorine determination in plutonium metal using phyrohydrolysis; spectrophotometric determination of 238-plutonium in oxide; plutonium measurement capabilities at the Savannah River Plant; and robotics in radiochemical laboratory

  14. Subcellular compartmentalization of Cd and Zn in two bivalves. II. Significance of trophically available metal (TAM)

    Science.gov (United States)

    Wallace, W.G.; Luoma, S.N.

    2003-01-01

    This paper examines how the subcellular partitioning of Cd and Zn in the bivalves Macoma balthica and Potamocorbula amurensis may affect the trophic transfer of metal to predators. Results show that the partitioning of metals to organelles, 'enzymes' and metallothioneins (MT) comprise a subcellular compartment containing trophically available metal (TAM; i.e. metal trophically available to predators), and that because this partitioning varies with species, animal size and metal, TAM is similarly influenced. Clams from San Francisco Bay, California, were exposed for 14 d to 3.5 ??g 1-1 Cd and 20.5 ??g 1-1 Zn, including 109Cd and 65Zn as radiotracers, and were used in feeding experiments with grass shrimp Palaemon macrodatylus, or used to investigate the subcellular partitioning of metal. Grass shrimp fed Cd-contaminated P. amurensis absorbed ???60% of ingested Cd, which was in accordance with the partitioning of Cd to the bivalve's TAM compartment (i.e. Cd associated with organelles, 'enzymes' and MT); a similar relationship was found in previous studies with grass shrimp fed Cd-contaminated oligochaetes. Thus, TAM may be used as a tool to predict the trophic transfer of at least Cd. Subcellular fractionation revealed that ???34% of both the Cd and Zn accumulated by M. balthica was associated with TAM, while partitioning to TAM in P. amurensis was metal-dependent (???60% for TAM-Cd%, ???73% for TAM-Zn%). The greater TAM-Cd% of P. amurensis than M. balthica is due to preferential binding of Cd to MT and 'enzymes', while enhanced TAM-Zn% of P. amurensis results from a greater binding of Zn to organelles. TAM for most species-metal combinations was size-dependent, decreasing with increased clam size. Based on field data, it is estimated that of the 2 bivalves, P. amurensis poses the greater threat of Cd exposure to predators because of higher tissue concentrations and greater partitioning as TAM; exposure of Zn to predators would be similar between these species.

  15. Validation for 2D/3D registration II: The comparison of intensity- and gradient-based merit functions using a new gold standard data set

    International Nuclear Information System (INIS)

    Gendrin, Christelle; Markelj, Primoz; Pawiro, Supriyanto Ardjo; Spoerk, Jakob; Bloch, Christoph; Weber, Christoph; Figl, Michael; Bergmann, Helmar; Birkfellner, Wolfgang; Likar, Bostjan; Pernus, Franjo

    2011-01-01

    Purpose: A new gold standard data set for validation of 2D/3D registration based on a porcine cadaver head with attached fiducial markers was presented in the first part of this article. The advantage of this new phantom is the large amount of soft tissue, which simulates realistic conditions for registration. This article tests the performance of intensity- and gradient-based algorithms for 2D/3D registration using the new phantom data set. Methods: Intensity-based methods with four merit functions, namely, cross correlation, rank correlation, correlation ratio, and mutual information (MI), and two gradient-based algorithms, the backprojection gradient-based (BGB) registration method and the reconstruction gradient-based (RGB) registration method, were compared. Four volumes consisting of CBCT with two fields of view, 64 slice multidetector CT, and magnetic resonance-T1 weighted images were registered to a pair of kV x-ray images and a pair of MV images. A standardized evaluation methodology was employed. Targets were evenly spread over the volumes and 250 starting positions of the 3D volumes with initial displacements of up to 25 mm from the gold standard position were calculated. After the registration, the displacement from the gold standard was retrieved and the root mean square (RMS), mean, and standard deviation mean target registration errors (mTREs) over 250 registrations were derived. Additionally, the following merit properties were computed: Accuracy, capture range, number of minima, risk of nonconvergence, and distinctiveness of optimum for better comparison of the robustness of each merit. Results: Among the merit functions used for the intensity-based method, MI reached the best accuracy with an RMS mTRE down to 1.30 mm. Furthermore, it was the only merit function that could accurately register the CT to the kV x rays with the presence of tissue deformation. As for the gradient-based methods, BGB and RGB methods achieved subvoxel accuracy (RMS m

  16. Crystal growth, characterization and theoretical studies of alkaline earth metal-doped tetrakis(thiourea)nickel(II) chloride.

    Science.gov (United States)

    Agilandeshwari, R; Muthu, K; Meenatchi, V; Meena, K; Rajasekar, M; Aditya Prasad, A; Meenakshisundaram, S P

    2015-02-25

    The influence of Sr(II)-doping on the properties of tetrakis(thiourea)nickel(II) chloride (TTNC) has been described. The reduction in the intensity observed in powder X-ray diffraction of doped specimen and slight shifts in vibrational frequencies of doped specimens confirm the lattice stress as a result of doping. Surface morphological changes due to doping of the Sr(II) are observed by scanning electron microscopy. The incorporation of metal into the host crystal lattice was confirmed by energy dispersive X-ray spectroscopy. Lattice parameters are determined by single crystal XRD analysis. The thermogravimetric and differential thermal analysis studies reveal the purity of the materials and no decomposition is observed up to the melting point. The nonlinear optical properties of the doped and undoped specimens were studied. Theoretical calculations were performed using the Density functional theory (DFT) method with B3LYP/LANL2DZ as the basis set. The molecular geometry and vibrational frequencies of TTNC in the ground state were calculated and the observed structural parameters of TTNC are compared with parameters obtained from single crystal X-ray studies. The atomic charge distributions are obtained by Mulliken charge population analysis. The first-order molecular hyperpolarizability, polarizability and dipole moment were derived. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Coordination of two high-affinity hexamer peptides to copper(II) and palladium(II) models of the peptide-metal chelation site on IMAC resins.

    Science.gov (United States)

    Chen, Y; Pasquinelli, R; Ataai, M; Koepsel, R R; Kortes, R A; Shepherd, R E

    2000-03-20

    The coordination of peptides Ser-Pro-His-His-Gly-Gly (SPHHGG) and (His)6 (HHHHHH) to [PdII(mida)(D2O)] (mida2- = N-methyliminodiacetate) was studied by 1H NMR as model reactions for CuII(iminodiacetate)-immobilized metal affinity chromatography (IMAC) sites. This is the first direct physical description of peptide coordination for IMAC. A three-site coordination is observed which involves the first, third, and fourth residues along the peptide chain. The presence of proline in position 2 of SPHHGG achieves the best molecular mechanics and bonding angles in the coordinated peptide and enhances the interaction of the serine amino nitrogen. Histidine coordination of H1, H3, and H4 of (His)6 and H3 and H4 of SPHHGG was detected by 1H NMR contact shifts and H/D exchange of histidyl protons. The EPR spectra of SPHHGG and HHHHHH attached to the [CuII(mida)] unit were obtained for additional modeling of IMAC sites. EPR parameters of the parent [Cu(mida)(H2O)2] complex are representative: gzz = 2.31; gyy = 2.086; gxx = 2.053; A parallel = 161G; AN = 19G (three line, one N coupling). Increased rhombic distortion is detected relative to the starting aqua complex in the order of [Cu(mida)L] for distortion of HHHHHH > SPHHGG > (H2O)2. The lowering of symmetry is also seen in the decrease in the N-shf coupling, presumably to the imino nitrogen of mida2- in the order 19 G (H2O), 16 G (SPHHGG) and 11 G (HHHHHH). Visible spectra of the [Cu(mida)(SPHHGG)] and [Cu(mida)(HHHHHH)] as a function of pH indicate coordination of one histidyl donor at ca. 4.5, two in the range of pH 5-7, and two chelate ring attachments involving the terminal amino donor for SPHHGG or another histidyl donor of HHHHHH in the pH domain of 7-8 in agreement with the [PdII(mida)L] derivatives which form the two-chelate-ring attachment even at lower pH as shown by the 1H NMR methods.

  18. STAR CLUSTERS IN M31. II. OLD CLUSTER METALLICITIES AND AGES FROM HECTOSPEC DATA

    International Nuclear Information System (INIS)

    Caldwell, Nelson; Schiavon, Ricardo; Morrison, Heather; Harding, Paul; Rose, James A.

    2011-01-01

    We present new high signal-to-noise spectroscopic data on the M31 globular cluster (GC) system, obtained with the Hectospec multifiber spectrograph on the 6.5 m MMT. More than 300 clusters have been observed at a resolution of 5 A and with a median S/N of 75 per A, providing velocities with a median uncertainty of 6 km s -1 . The primary focus of this paper is the determination of mean cluster metallicities, ages, and reddenings. Metallicities were estimated using a calibration of Lick indices with [Fe/H] provided by Galactic GCs. These match well the metallicities of 24 M31 clusters determined from Hubble Space Telescope color-magnitude diagrams, the differences having an rms of 0.2 dex. The metallicity distribution is not generally bimodal, in strong distinction with the bimodal Galactic globular distribution. Rather, the M31 distribution shows a broad peak, centered at [Fe/H] = -1, possibly with minor peaks at [Fe/H] = -1.4, -0.7, and -0.2, suggesting that the cluster systems of M31 and the Milky Way had different formation histories. Ages for clusters with [Fe/H] > - 1 were determined using the automatic stellar population analysis program EZ A ges. We find no evidence for massive clusters in M31 with intermediate ages, those between 2 and 6 Gyr. Moreover, we find that the mean ages of the old GCs are remarkably constant over about a decade in metallicity (-0.95∼< [Fe/H] ∼<0.0).

  19. Evaluation for the effects of a ring plate device to eliminate free surface gradients in liquid metal fast breeder reactor vessel using multi-dimensional thermohydraulics computer code

    International Nuclear Information System (INIS)

    Gao Ming Qing.

    1997-02-01

    There is a free surface at the upper plenum in a reactor vessel of LMFBR. The free surface has spatial gradient caused by the internal coolant flow. This is a disadvantageous factor to engineering from the view point of gas entrainment into coolant. To eliminate the free surface gradients, ring plates about 20 cm wide are fitted at about 1 meter under the free surface. They interfere fluid flow, and decrease the component velocity in vertical direction. To investigate the efficiency of the ring plates, analyses with the AQUA-VOF code were carried out. For contrast, three conditions were given: Case-1: Without ring plates. Case-2: Ring plates, fitted at 1.125 m under the free surface. Case-3: Ring plates, fitted at 1.5 m under the free surface. The results shown that the ring plates have a sufficiently high potential to eliminate the free surface gradients due to disperse the momentum along reactor vessel axis to radial direction. In the calculations with ring plate (Cases-2 and -3), the maximum free surface height differences and the maximum gradients of free surface were decreased to less than 15% and 64% compared with the case without ring plates, respectively. (author)

  20. Synthesis, crystal structure and DFT calculations of a new Hg (II) metal-organic polymer

    Czech Academy of Sciences Publication Activity Database

    Mirtamizdoust, B.; Roodsari, M.S.; Shaabani, B.; Dušek, Michal; Fejfarová, Karla

    2016-01-01

    Roč. 15, č. 3 (2016), s. 257-266 ISSN 1024-1221 Grant - others:AV ČR(CZ) Praemium Academiae Institutional support: RVO:68378271 Keywords : mercury (II) iodide * coordination polymer * square planar * tetrahedral geometry * density functional calculation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.565, year: 2016

  1. Stability Constants of Mixed Ligand Complexes of Transition Metal(II Ions with Salicylidene-4-methoxyaniline as Primary Ligand and 5-Bromosalicylidene-4-nitroaniline as Secondary Ligand

    Directory of Open Access Journals (Sweden)

    N. G. Nadkarni

    2011-01-01

    Full Text Available Binary and ternary complexes of the type M-Y and M-X-Y [M = Mn(II, Ni(II, Cu(II and Zn(II; X = salicylidene-4-methoxyaniline and Y=5-bromosalicylidene-4-nitroaniline] have been examined pH-metrically at 27±0.5 °C and at constant ionic strength, μ= 0.1 M (KCl in 75 : 25(v/v 1,4-dioxne-water medium. The stability constants for binary (M-Y and ternary (M-X-Y systems were calculated. The relative stability (Δ log KT values of the ternary complexes with corresponding binary complexes for all the metal(II ions in the present study found to be negative indicating that ternary 1:1:1 (M-X-Y complexes are less stable than binary 1:1 (M-Y complexes. In the ternary system studied, the order of stability constants of mixed ligand complexes with respect to the metal ions was found to be Cu(II > NI(II > Mn(II > Zn(II; which is same as in the corresponding binary (M-Y systems.

  2. Sources of variation in innate immunity in great tit nestlings living along a metal pollution gradient: An individual-based approach

    NARCIS (Netherlands)

    Vermeulen, A.; Müller, W.; Matson, K.D.; Tieleman, B.I.; Bervoets, L.; Eens, M.

    2015-01-01

    Excessive deposition of metals in the environment is a well-known example of pollution worldwide. Chronic exposure of organisms to metals can have a detrimental effect on reproduction, behavior, health and survival, due to the negative effects on components of the immune system. However, little is

  3. Sources of variation in innate immunity in great tit nestlings living along a metal pollution gradient : An individual-based approach

    NARCIS (Netherlands)

    Vermeulen, Anke; Muller, Wendt; Matson, Kevin D.; Tieleman, B. Irene; Bervoets, Lieven; Eens, Marcel

    2015-01-01

    Excessive deposition of metals in the environment is a well-known example of pollution worldwide. Chronic exposure of organisms to metals can have a detrimental effect on reproduction, behavior, health and survival, due to the negative effects on components of the immune system. However, little is

  4. Heavy Metals (Mg, Mn, Ni and Sn contamination in Soil Samples of Ahvaz II Industrial Estate of Iran in 2013

    Directory of Open Access Journals (Sweden)

    Soheil l Sobhanardakani

    2016-04-01

    Full Text Available Background & Aims of the Study: Due to the rapid industrial development in Khuzestan province of Iran during recent years, this study was performed to analyze the variation of metals concentrations (Mg, Mn, Ni, and Sn in soil samples of Ahvaz II Industrial estate during the spring season of 2013. Materials & Methods: In this experimental study, 27 topsoil samples were collected from nine stations. The intensity of the soil contamination was evaluated, using a contamination factor (Cf and geo-accumulation index (I-geo. Results:  The mean soil concentrations (in mg kg-1 (dry weight were in ranged within 870-1144 (Mg, 188-300 (Mn, 93-199 (Ni and 9-15 (Sn. The data indicated that the I-geo value for all metals falls in class ‘1’. Also the Cf value for Mg and Mn falls in class ‘0’, the Cf value for Sn falls in class ‘1’ and the Cf value for Ni falls in the classes of ‘1’ and ‘2’. The result of the Pearson correlation showed that there were significant positive associations between all metals. Conclusions: According to the results which were achieved by a cluster analysis, there were significant positive associations among all metals based on Pearson correlation coefficient, especially between Ni and Sn; also both of them with Mn. Because the Ni originates from oil sources it can be resulted that Mn and Sn originate from oil sources, too. Therefore, industrial activities and exploitation of oil reservoirs are the main cause of pollution in that area. Also, it can be concluded that, with increasing the distance from the source of pollution, the accumulation of contaminants in the soil samples decreased.

  5. Pareto-Lognormal Modeling of Known and Unknown Metal Resources. II. Method Refinement and Further Applications

    International Nuclear Information System (INIS)

    Agterberg, Frits

    2017-01-01

    Pareto-lognormal modeling of worldwide metal deposit size–frequency distributions was proposed in an earlier paper (Agterberg in Nat Resour 26:3–20, 2017). In the current paper, the approach is applied to four metals (Cu, Zn, Au and Ag) and a number of model improvements are described and illustrated in detail for copper and gold. The new approach has become possible because of the very large inventory of worldwide metal deposit data recently published by Patiño Douce (Nat Resour 25:97–124, 2016c). Worldwide metal deposits for Cu, Zn and Ag follow basic lognormal size–frequency distributions that form straight lines on lognormal Q–Q plots. Au deposits show a departure from the straight-line model in the vicinity of their median size. Both largest and smallest deposits for the four metals taken as examples exhibit hyperbolic size–frequency relations and their Pareto coefficients are determined by fitting straight lines on log rank–log size plots. As originally pointed out by Patiño Douce (Nat Resour Res 25:365–387, 2016d), the upper Pareto tail cannot be distinguished clearly from the tail of what would be a secondary lognormal distribution. The method previously used in Agterberg (2017) for fitting the bridge function separating the largest deposit size–frequency Pareto tail from the basic lognormal is significantly improved in this paper. A new method is presented for estimating the approximate deposit size value at which the upper tail Pareto comes into effect. Although a theoretical explanation of the proposed Pareto-lognormal distribution model is not a required condition for its applicability, it is shown that existing double Pareto-lognormal models based on Brownian motion generalizations of the multiplicative central limit theorem are not applicable to worldwide metal deposits. Neither are various upper tail frequency amplification models in their present form. Although a physicochemical explanation remains possible, it is argued that

  6. Pareto-Lognormal Modeling of Known and Unknown Metal Resources. II. Method Refinement and Further Applications

    Energy Technology Data Exchange (ETDEWEB)

    Agterberg, Frits, E-mail: agterber@nrcan.gc.ca [Geological Survey of Canada (Canada)

    2017-07-01

    Pareto-lognormal modeling of worldwide metal deposit size–frequency distributions was proposed in an earlier paper (Agterberg in Nat Resour 26:3–20, 2017). In the current paper, the approach is applied to four metals (Cu, Zn, Au and Ag) and a number of model improvements are described and illustrated in detail for copper and gold. The new approach has become possible because of the very large inventory of worldwide metal deposit data recently published by Patiño Douce (Nat Resour 25:97–124, 2016c). Worldwide metal deposits for Cu, Zn and Ag follow basic lognormal size–frequency distributions that form straight lines on lognormal Q–Q plots. Au deposits show a departure from the straight-line model in the vicinity of their median size. Both largest and smallest deposits for the four metals taken as examples exhibit hyperbolic size–frequency relations and their Pareto coefficients are determined by fitting straight lines on log rank–log size plots. As originally pointed out by Patiño Douce (Nat Resour Res 25:365–387, 2016d), the upper Pareto tail cannot be distinguished clearly from the tail of what would be a secondary lognormal distribution. The method previously used in Agterberg (2017) for fitting the bridge function separating the largest deposit size–frequency Pareto tail from the basic lognormal is significantly improved in this paper. A new method is presented for estimating the approximate deposit size value at which the upper tail Pareto comes into effect. Although a theoretical explanation of the proposed Pareto-lognormal distribution model is not a required condition for its applicability, it is shown that existing double Pareto-lognormal models based on Brownian motion generalizations of the multiplicative central limit theorem are not applicable to worldwide metal deposits. Neither are various upper tail frequency amplification models in their present form. Although a physicochemical explanation remains possible, it is argued that

  7. Simulation of elution profiles in liquid chromatography - II: Investigation of injection volume overload under gradient elution conditions applied to second dimension separations in two-dimensional liquid chromatography.

    Science.gov (United States)

    Stoll, Dwight R; Sajulga, Ray W; Voigt, Bryan N; Larson, Eli J; Jeong, Lena N; Rutan, Sarah C

    2017-11-10

    An important research direction in the continued development of two-dimensional liquid chromatography (2D-LC) is to improve the detection sensitivity of the method. This is especially important in applications where injection of large volumes of effluent from the first dimension ( 1 D) column into the second dimension ( 2 D) column leads to severe 2 D peak broadening and peak shape distortion. For example, this is common when coupling two reversed-phase columns and the organic solvent content of the 1 D mobile phase overwhelms the 2 D column with each injection of 1 D effluent, leading to low resolution in the second dimension. In a previous study we validated a simulation approach based on the Craig distribution model and adapted from the work of Czok and Guiochon [1] that enabled accurate simulation of simple isocratic and gradient separations with very small injection volumes, and isocratic separations with mismatched injection and mobile phase solvents [2]. In the present study we have extended this simulation approach to simulate separations relevant to 2D-LC. Specifically, we have focused on simulating 2 D separations where gradient elution conditions are used, there is mismatch between the sample solvent and the starting point in the gradient elution program, injection volumes approach or even exceed the dead volume of the 2 D column, and the extent of sample loop filling is varied. To validate this simulation we have compared results from simulations and experiments for 101 different conditions, including variation in injection volume (0.4-80μL), loop filling level (25-100%), and degree of mismatch between sample organic solvent and the starting point in the gradient elution program (-20 to +20% ACN). We find that that the simulation is accurate enough (median errors in retention time and peak width of -1.0 and -4.9%, without corrections for extra-column dispersion) to be useful in guiding optimization of 2D-LC separations. However, this requires that real

  8. Application of Y-shaped, coated self-expandable metallic stents for anastomotic stenosis after gastrojejunostomy (Billroth II).

    Science.gov (United States)

    Li, Teng-Fei; Wu, Gang; Han, Xin-Wei; Shui, Shao-Feng; Ren, Jian-Zhuang; Li, Zhen; Ren, Ke-Wei

    2017-01-01

    Anastomotic stenosis is an infrequent but life-threatening complication after gastrojejunostomy (Billroth II). Tubular or single tubular stents have limited efficacy due to the particular anatomy. To assess the feasibility of a Y-shaped, fully-coated, self-expandable, metallic stent (SEMS) for anastomotic stenosis after gastrojejunostomy (Billroth II). Between January 2008 and August 2014, 14 patients (10 with gastric carcinoma and four with duodenal ulcers) had anastomotic stenoses following Billroth II reconstructions. Eight patients with gastric cancer had tumor recurrence near the anastomosis; two had benign strictures. The four duodenal ulcer patients had benign stenoses. An integrated Y-shaped, fully coated SEMS was designed to accord with the anatomy of residual gastrojejunal anastomotic strictures. Fourteen stents were inserted under fluoroscopic control. Follow-up was at 1, 3, 9, and 12 months, and then annually. All 14 stents were inserted successfully at the first attempt with a technical success rate of 100%. After stenting, abdominal symptoms resolved in all patients. All patients were followed up for 4-27 months (mean, 13.9 months). One of the eight recurrent cases died of multiple tumor metastases and liver failure after 7 months, without obstruction symptoms. In all six patients with benign anastomotic stenosis, the stents were removed successfully without complication and with no evidence of restenosis based on clinical evaluation and imaging. A Y-shaped, fully-coated SEMS proved to be a feasible and minimally invasive procedure for treating anastomotic stenosis after gastrojejunostomy (Billroth II). © The Foundation Acta Radiologica 2016.

  9. Color gradients in elliptical galaxies

    International Nuclear Information System (INIS)

    Franx, M.; Illingworth, G.

    1990-01-01

    The relationship of the color gradients within ellipticals and the color differences between them are studied. It is found that the local color appears to be strongly related to the escape velocity. This suggests that the local escape velocity is the primary factor that determines the metallicity of the stellar population. Models with and without dark halos give comparable results. 27 refs

  10. Analysis of metal-matrix composite structures. I - Micromechanics constitutive theory. II - Laminate analyses

    Science.gov (United States)

    Arenburg, R. T.; Reddy, J. N.

    1991-01-01

    The micromechanical constitutive theory is used to examine the nonlinear behavior of continuous-fiber-reinforced metal-matrix composite structures. Effective lamina constitutive relations based on the Abouli micromechanics theory are presented. The inelastic matrix behavior is modeled by the unified viscoplasticity theory of Bodner and Partom. The laminate constitutive relations are incorporated into a first-order deformation plate theory. The resulting boundary value problem is solved by utilizing the finite element method. Attention is also given to computational aspects of the numerical solution, including the temporal integration of the inelastic strains and the spatial integration of bending moments. Numerical results the nonlinear response of metal matrix composites subjected to extensional and bending loads are presented.

  11. On Phonons in Simple Metals II. Calculated Dispersion Curves In Aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R [AB Atomenergi, Nykoeping (Sweden); Westin, A [Dept. of Theore tical Physics, Univ. of Uppsala, Uppsala (Sweden)

    1969-07-15

    The real part of the dynamical matrix, derived earlier in a weak local potential ion-electron interaction model of the metal, is investigated in the case of aluminium. It is shown that the free electron, or Lindhard, dielectric function leads to a picture of the metal which is inconsistent with the dHvA observations of the Fermi surface. By adjusting one parameter, however, the experimental phonon frequencies are reproduced satisfactorily. Even some simple structure in the derivative d{omega}/dq can be reproduced in this way. Although corrections to the Lindhard dielectric matrix give no essential contributions to the dynamical matrix, the first order corrections, which are the most important, can explain the observed Fermi surface. Much of the observed structure in the phonon dispersion curves seems also to be due to these non-diagonal terms in the dielectric matrix.

  12. Radiation-chemical decomposition of heavy metal azides - II. Silver azide radiolysis scheme

    International Nuclear Information System (INIS)

    Ryabykh, S.M.

    1987-01-01

    As a result of complex studies on the nature and properties of final products and intermediate particles using a wide number of experimental topography and radiolysis kinetics methods, we offer the AgN 3 radiolysis scheme including the following stages: homogeneous excitation of electron subsystem with 'hot' electrons and holes formed; 'hot' electron and hole thermalization with possible formation of N 4 - radical in volume on the point defects; electron localization on the immobile structural defects whose neighbourhood is rich in the mobile positively charged point defects; metal particle formation due to electrostatic attraction of the nearby mobile defect to the localized electron, with no thermal excitation; metal particle growth, according to both the diffusional mechanism of delivering the volume of corresponding positively charged point defect with consequent electron capture, and by decomposing anions on the interphase with the consequent border layer cation addition to the growing metal particle, interior space formation in the volume by disintegrating 'hot' excitons into ion defect pairs; nitrogen formation on the exterior and interior surfaces, as well as those formed by radiation, either by trapping the hole by surface cation vacancy or by removing the surface cation of the hole with the consequent addition of the second hole to the Vsub(F)-center, and by disintegrating the activated complex into three nitrogen molecules. For the above stages the characteristic parameters are determined by means of direct measurement and calculation. The kinetics and energy conditions of the process are also found. (author)

  13. The study on recycle scheme of the metallic radioactive wastes (II)

    International Nuclear Information System (INIS)

    Shin, J. I.; Park, J. H.; Jung, K. J.

    2003-01-01

    It was understood that regulation criteria for material release varied with countries and that international standards were not setup. But, most advanced countries are continuously studying on the recycling of metallic wastes for the purpose of the reuse of resources and disposal cost reduction. Practically, the advanced countries make a lot of cost profits compared with disposal as their metallic wastes are recycled and reused through technology like melting. The reasonable international standards are also expected to be set in the near future because of the aggressive cooperation between international agencies such as IAEA and NEA toward recycling these wastes. In our case, the recycle criteria for radioactive waste containing radioactive nuclide with long half-life such as Cs-137(half-life: 30y) and Co-60(half-life: 5.26y) including others, which are generated from the nuclear fission or dismantling of nuclear facilities, are not yet established. Therefore, it is required that the recommendation and legalization of the regulatory criteria be carried out for the recycle and reuse of metallic wastes to be generated from the dismantling of domestic nuclear facilities in the future

  14. Synthesis, characterization and application of Lanthanide metal-ion-doped TiO2/bentonite nanocomposite for removal of Lead (II and Cadmium (II from aquatic media

    Directory of Open Access Journals (Sweden)

    Susan Samadi

    2016-07-01

    Full Text Available The efficient application of the photocatalytic activity and superficial adsorption on removing heavy metals from water, two types of sorbents, Nd-TiO2/bentonite and Ce-TiO2/bentonite nanocomposites, were synthesized by sol-gel method. The crystalline nanocomposites were obtained after heat treatment at 500 °C for 3 hours. The results of scanning electron microscopy (SEM indicates that Nd-TiO2/bentonite and Ce-TiO2/bentonite were produced on a nanoscale. The phase change of both nanocomposite from amorphous to anatase has been investigated by X- ray diffraction. Removal of lead (II and cadmium (II were studied through adsorption on these nanocomposites by letting them float in the bulk of sample for a definite time in presence and absence of light. The effective parameters in removal process were studied and optimized. The optimum pH, removal time and sorbent dosage in the absence and presence of light for Pb2+ ion were 7, 0.3 g, 15 min and for Cd2+ ion were 7, 0.4 g, 20 min, respectively. Subsequently, the effect of interfering ions in removal process was investigated at optimum conditions and no evidence of interference was observed. The study showed that reproducibility of method (n=9 is good and suitable. The results further indicated that the removal efficiency of Pb2+ ion with Nd-TiO2/bentonite in the presence of light was more than that in the absence of light. Finally, the equilibrium adsorption data fitted Freundlich and Langmuir adsorption models.

  15. X447 EBR-II Experiment Benchmark for Verification of Audit Code of SFR Metal Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yong Won; Bae, Moo-Hoon; Shin, Andong; Suh, Namduk [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2016-10-15

    In KINS (Korea Institute of Nuclear Safety), to prepare audit calculation of PGSFR licensing review, the project has been started to develop the regulatory technology for SFR system including a fuel area. To evaluate the fuel integrity and safety during an irradiation, the fuel performance code must be used for audit calculation. In this study, to verify the new code system, the benchmark analysis is performed. In the benchmark, X447 EBR-II experiment data are used. Additionally, the sensitivity analysis according to mass flux change of coolant is performed. In case of LWR fuel performance modeling, various and advanced models have been proposed and validated based on sufficient in-reactor test results. However, due to the lack of experience of SFR operation, the current understanding of SFR fuel behavior is limited. In this study, X447 EBR-II Experiment data are used for benchmark. The fuel composition of X447 assembly is U-10Zr and PGSFR also uses this composition in initial phase. So we select X447 EBR-II experiment for benchmark analysis. Due to the lack of experience of SFR operation and data, the current understanding of SFR fuel behavior is limited. However, in order to prepare the licensing of PGSFR, regulatory audit technologies of SFR must be secured. So, in this study, to verify the new audit fuel performance analysis code, the benchmark analysis is performed using X447 EBR-II experiment data. Also, the sensitivity analysis with mass flux change of coolant is performed. In terms of verification, it is considered that the results of benchmark and sensitivity analysis are reasonable.

  16. X447 EBR-II Experiment Benchmark for Verification of Audit Code of SFR Metal Fuel

    International Nuclear Information System (INIS)

    Choi, Yong Won; Bae, Moo-Hoon; Shin, Andong; Suh, Namduk

    2016-01-01

    In KINS (Korea Institute of Nuclear Safety), to prepare audit calculation of PGSFR licensing review, the project has been started to develop the regulatory technology for SFR system including a fuel area. To evaluate the fuel integrity and safety during an irradiation, the fuel performance code must be used for audit calculation. In this study, to verify the new code system, the benchmark analysis is performed. In the benchmark, X447 EBR-II experiment data are used. Additionally, the sensitivity analysis according to mass flux change of coolant is performed. In case of LWR fuel performance modeling, various and advanced models have been proposed and validated based on sufficient in-reactor test results. However, due to the lack of experience of SFR operation, the current understanding of SFR fuel behavior is limited. In this study, X447 EBR-II Experiment data are used for benchmark. The fuel composition of X447 assembly is U-10Zr and PGSFR also uses this composition in initial phase. So we select X447 EBR-II experiment for benchmark analysis. Due to the lack of experience of SFR operation and data, the current understanding of SFR fuel behavior is limited. However, in order to prepare the licensing of PGSFR, regulatory audit technologies of SFR must be secured. So, in this study, to verify the new audit fuel performance analysis code, the benchmark analysis is performed using X447 EBR-II experiment data. Also, the sensitivity analysis with mass flux change of coolant is performed. In terms of verification, it is considered that the results of benchmark and sensitivity analysis are reasonable

  17. Synthesis of high-surface-area γ-Al2O3 from aluminum scrap and its use for the adsorption of metals: Pb(II), Cd(II) and Zn(II)

    International Nuclear Information System (INIS)

    Asencios, Yvan J.O.; Sun-Kou, María R.

    2012-01-01

    Highlights: ► Aluminum hydroxide obtained from aluminum scrap led to the formation of gamma alumina. ► Acidic pH of precipitation favored the formation of small particles of high surface areas. ► Higher aging temperature favored the formation of large structures of large pore sizes. ► Higher aging temperature generated symmetrical solids of regular hexagonal prism forms. ► Aluminas of large pores adsorbed metals as following: Pb (1.75 Å) > Cd (1.54 Å) > Zn (1.38 Å). - Abstract: Several types of alumina were synthesized from sodium aluminate (NaAlO 2 ) by precipitation with sulfuric acid (H 2 SO 4 ) and subsequently calcination at 500 °C to obtain γ-Al 2 O 3 . The precursor aluminate was derived from aluminum scrap. The various γ-Al 2 O 3 synthesized were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), adsorption–desorption of N 2 (S BET ) and scanning electron microscopy (SEM). XRD revealed that distinct phases of Al 2 O 3 were formed during thermal treatment. Moreover, it was observed that conditions of synthesis (pH, aging time and temperature) strongly affect the physicochemical properties of the alumina. A high-surface-area alumina (371 m 2 g −1 ) was synthesized under mild conditions, from inexpensive raw materials. These aluminas were tested for the adsorption of Cd(II), Zn(II) and Pb(II) from aqueous solution at toxic metal concentrations, and isotherms were determined.

  18. Tetra- and octa-[4-(2-hydroxyethyl)phenoxy bearing novel metal-free and zinc(II) phthalocyanines: Synthesis, characterization and investigation of photophysicochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Köksoy, Baybars [Marmara University, Department of Chemistry, 34722 Kadıköy, Istanbul (Turkey); Durmuş, Mahmut [Gebze Technical University, Department of Chemistry, 41400 Gebze, Kocaeli (Turkey); Bulut, Mustafa, E-mail: mbulut@marmara.edu.tr [Marmara University, Department of Chemistry, 34722 Kadıköy, Istanbul (Turkey)

    2015-05-15

    In this study, four novel phthalonitriles (1–4) and their corresponding metal-free (5–8) and zinc(II) phthalocyanine derivatives (9–12) bearing 4-(hydroxyethyl)phenoxy groups were synthesized. These novel compounds were characterized by IR, elemental analyses, {sup 1}H-NMR, UV–vis, and MALDI-TOF spectral data. Furthermore, photophysical (fluorescence quantum yields and lifetimes) and photochemical properties (singlet oxygen generation and photodegradation quantum yields) of these phthalocyanines were investigated in dimethylsulfoxide. The studied zinc(II) phthalocyanines generated highly singlet oxygen which is very important for the photodynamic therapy (PDT) of cancer. The fluorescence quenching behaviour of the newly synthesized phthalocyanine compounds were also investigated using 1,4-benzoquinone. - Highlights: • Octa and tetra 4-(hydroxyethyl)phenoxy substituted metal-free and zinc(II) phthalocyanines. • Study of photophysicochemical properties of eight new phthalocyanines. • Highly singlet oxygen generation for novel zinc(II) phthalocyanine photosensitizers.

  19. Review of the SIMMER-II analyses of liquid-metal-cooled fast breeder reactor core-disruptive accident fuel escape

    International Nuclear Information System (INIS)

    DeVault, G.P.; Bell, C.R.

    1985-01-01

    Early fuel removal from the active core of a liquid-metal-cooled fast breeder reactor undergoing a core-disruptive accident may reduce the potential for large energetics resulting from recriticalities. This paper presents a review of analyses with the SIMMER-II computer program of the effectiveness of possible fuel escape paths. Where possible, how SIMMER-II compares with or is validated against experiments that simulated the escape paths also is discussed

  20. SDSS-IV MaNGA: the impact of diffuse ionized gas on emission-line ratios, interpretation of diagnostic diagrams and gas metallicity measurements

    Science.gov (United States)

    Zhang, Kai; Yan, Renbin; Bundy, Kevin; Bershady, Matthew; Haffner, L. Matthew; Walterbos, René; Maiolino, Roberto; Tremonti, Christy; Thomas, Daniel; Drory, Niv; Jones, Amy; Belfiore, Francesco; Sánchez, Sebastian F.; Diamond-Stanic, Aleksandar M.; Bizyaev, Dmitry; Nitschelm, Christian; Andrews, Brett; Brinkmann, Jon; Brownstein, Joel R.; Cheung, Edmond; Li, Cheng; Law, David R.; Roman Lopes, Alexandre; Oravetz, Daniel; Pan, Kaike; Storchi Bergmann, Thaisa; Simmons, Audrey

    2017-04-01

    Diffuse ionized gas (DIG) is prevalent in star-forming galaxies. Using a sample of 365 nearly face-on star-forming galaxies observed by Mapping Nearby Galaxies at APO, we demonstrate how DIG in star-forming galaxies impacts the measurements of emission-line ratios, hence the interpretation of diagnostic diagrams and gas-phase metallicity measurements. At fixed metallicity, DIG-dominated low ΣHα regions display enhanced [S II]/Hα, [N II]/Hα, [O II]/Hβ and [O I]/Hα. The gradients in these line ratios are determined by metallicity gradients and ΣHα. In line ratio diagnostic diagrams, contamination by DIG moves H II regions towards composite or low-ionization nuclear emission-line region (LI(N)ER)-like regions. A harder ionizing spectrum is needed to explain DIG line ratios. Leaky H II region models can only shift line ratios slightly relative to H II region models, and thus fail to explain the composite/LI(N)ER line ratios displayed by DIG. Our result favours ionization by evolved stars as a major ionization source for DIG with LI(N)ER-like emission. DIG can significantly bias the measurement of gas metallicity and metallicity gradients derived using strong-line methods. Metallicities derived using N2O2 are optimal because they exhibit the smallest bias and error. Using O3N2, R23, N2 = [N II]/Hα and N2S2Hα to derive metallicities introduces bias in the derived metallicity gradients as large as the gradient itself. The strong-line method of Blanc et al. (IZI hereafter) cannot be applied to DIG to get an accurate metallicity because it currently contains only H II region models that fail to describe the DIG.

  1. Simple nonempirical calculations of the zero-field splitting in transition metal systems: I. The Ni(II)-water complexes

    International Nuclear Information System (INIS)

    Ribbing, C.; Odelius, M.; Laaksonen, A.; Kowalewski, J.; Roos, B.

    1990-01-01

    A simple nonempirical scheme is presented for calculating the splittings of ground state multiplets (the zero-field splitting) is transition metal complexes. The method employs single reference, single excitation CI calculations based on open-shell RHF. The spin-orbit coupling is described using an effective one-electron, one-center operators. The method is applied to the triplet state Ni(II) complexes with one to six water molecules. the validity of the second-order perturbation theory approach and of the spin-Hamiltonian formalism is found to be limited to slightly distorted octahedral systems. Generally, small changes in the geometries of the complexes are found to cause substantial variations of the splitting pattern

  2. Arsenic and metallic trace elements cycling in the surface water-groundwater-soil continuum down-gradient from a reclaimed mine area: Isotopic imprints

    Science.gov (United States)

    Khaska, Mahmoud; Le Gal La Salle, Corinne; Sassine, Lara; Cary, Lise; Bruguier, Olivier; Verdoux, Patrick

    2018-03-01

    One decade after closure of the Salsigne mine (SW France), As contamination persisted in surface water, groundwater and soil near and down-gradient from the reclaimed ore processing site (OPS). We assess the fate of As and other associated chalcophilic MTEs, and their transport in the surface-water/groundwater/soil continuum down-gradient from the reclaimed OPS, using Sr-isotopic fingerprinting. The Sr-isotope ratio was used as a tracer of transfer processes in this hydro-geosystem and was combined to sequential extraction of soil samples to evaluate the impact of contaminated soil on the underlying phreatic groundwater. The contrast in Sr isotope compositions of the different soil fractions reflects several Sr sources in the soil. In the complex hydro-geosystem around the OPS, the transport of As and MTEs is affected by a succession of factors, such as (1) Existence of a reducing zone in the aquifer below the reclaimed OPS, where groundwater shows relatively high As and MTEs contents, (2) Groundwater discharge into the stream near the reclaimed OPS causing an increase in As and MTE concentrations in surface water; (3) Partial co-precipitation of As with Fe-oxyhydroxides, contributing to some attenuation of As contents in surface water; (4) Infiltration of contaminated stream water into the unconfined aquifer down-gradient from the reclaimed OPS; (5) Accumulation of As and MTEs in soil irrigated with contaminated stream- and groundwater; (6) Release of As and MTEs from labile soil fractions to underlying the groundwater.

  3. Thermal convection in a toroidal duct of a liquid metal blanket. Part II. Effect of axial mean flow

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xuan, E-mail: xuanz@umich.edu; Zikanov, Oleg

    2017-03-15

    Highlights: • 2D convection flow develops with internal heating and strong axial magnetic field. • The flow is strongly modified by the buoyancy force associated with growing T{sub m}. • Thermal convection is suppressed at high Gr. • High temperature difference between top and bottom walls is expected at high Gr. - Abstract: The work continues the exploration of the effect of thermal convection on flows in toroidal ducts of a liquid metal blanket. This time we consider the effect of the mean flow along the duct and of the associated heat transfer diverting the heat deposited by captured neutrons. Numerical simulations are conducted for a model system with two-dimensional (streamwise-uniform) fully developed flow, purely toroidal magnetic field, and perfectly electrically and thermally insulating walls. Realistically high Grashof (up to 10{sup 11}) and Reynolds (up to 10{sup 6}) numbers are used. It is found that the flow develops thermal convection in the transverse plane at moderate Grashof numbers. At large Grashof numbers, the flow is dominated by the top-bottom asymmetry of the streamwise velocity and stable stratification of temperature, which are caused by the buoyancy force due to the mean temperature growing along the duct. This leads to suppression of thermal convection, weak mixing, and substantial gradients of wall temperature. Further analysis based on more realistic models is suggested.

  4. A novel route for the removal of bodily heavy metal lead (II)

    International Nuclear Information System (INIS)

    Huang, Weirong; Zhang, Penghua; Xu, Hui; He, Yongju; Wang, Fei; Liang, Gaowei; Chang, Shengli

    2015-01-01

    The lead ion concentration in bile is considerably higher than in blood, and bile is released into the alimentary tract. Thiol-modified SBA-15 administered orally can combine with lead ions in the alimentary tract. In this paper, the in vitro lead absorption of bile was investigated. This thiol-modified SBA-15 material was used in pharmacodynamics studies on rabbits. The result that the lead content in faeces was notably higher indicates that thiol-modified SBA-15 can efficiently remove lead. The mechanism could include the following: thiol-modified SBA-15 material cuts off the heavy metal lead recirculation in the process of bile enterohepatic circulation by chelating the lead in the alimentary tract, causing a certain proportion of lead to be removed by the thiol mesoporous material, and the lead is subsequently egested out of the body in faeces. The results indicate that this material might be a potential non-injection material for the removal bodily heavy metal lead in the alimentary tract. This material may also be a useful means of lead removal, especially for non-acute sub-poisoning symptoms. (paper)

  5. The intra-annular acylamide chelate-coordinated compound: The keto-tautomer of metal (II) milrinone complex

    Science.gov (United States)

    Gong, Yun; Liu, Jinzhi; Tang, Wang; Hu, Changwen

    2008-03-01

    In the presence of N, N'-dimethyllformamide (DMF), two isostructural metal (II)-milrinone complexes formulated as M(C 12H 8N 3O) 2 (M = Co 1 and Ni 2) have been synthesized and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. The two compounds crystallize in the tetragonal system, chiral space group P4 32 12. They exhibit similar two dimensional (2D) square grid-like framework, in which milrinone acts as a ditopic ligand with its terminal pyridine and intra-annular acylamide groups covalently bridging different metal centers. The intra-annular acylamide ligand shows a chelate-coordinated mode. Compounds 1 and 2 are stable under 200 °C. Compound 3 formulated as (C 12H 9N 3O) 4·H 2O was obtained in the presence of water, the water molecule in the structure leads to the racemization of compound 3 and it crystallizes in the monoclinic system, non-chiral space group P2 1/ c. Milrinone exhibits a keto-form in the three compounds and compounds 1- 3 exhibit different photoluminescence properties.

  6. CFA-13 - a bifunctional perfluorinated metal-organic framework featuring active Cu(i) and Cu(ii) sites.

    Science.gov (United States)

    Fritzsche, J; Denysenko, D; Grzywa, M; Volkmer, D

    2017-11-07

    The synthesis and crystal structure of the mixed-valent perfluorinated metal-organic framework (Me 2 NH 2 )[CFA-13] (Coordination Framework Augsburg University-13), (Me 2 NH 2 )[CuCu(tfpc) 4 ] (H 2 -tfpc = 3,5-bis(trifluoromethyl)-1H-pyrazole-4-carboxylic acid) is described. The copper-containing MOF crystallizes in the monoclinic crystal system within the space group P2 1 /n (no. 14) and the unit cell parameters are as follows: a = 22.3887(19), b = 13.6888(8), c = 21.1804(13) Å, β = 90.495(3)°, V = 6491.0(8) Å 3 . (Me 2 NH 2 )[CFA-13] features a porous 3-D structure constructed from two types of secondary building units (SBUs). Besides novel trinuclear [Cu(pz) 4 ] - coordination units, the network also exhibits Cu(ii) paddle-wheel SBUs. (Me 2 NH 2 )[CFA-13] is fully characterized by single crystal X-ray diffraction, thermogravimetric analysis, variable temperature powder X-ray diffraction, IR spectroscopy, photoluminescence, gas sorption measurements and pulse chemisorption experiments. M[CFA-13] (M = K + , Cs + ) frameworks were prepared by postsynthetic exchange of interchannel dimethylammonium cations. Moreover, it was shown that CO molecules can be selectively bound at Cu(i) sites of [Cu(pz) 4 ] - units, whereas Cu(ii) paddle-wheel units bind selectively NH 3 molecules.

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

    Science.gov (United States)

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

    2016-01-01

    Mercury (Hg) speciation and sorption analyses in contaminated aquifers are useful for understanding transformation, retention, and mobility of Hg in groundwater. In most aquifers hydrous ferric oxides (HFOs) are among the most important sorbents for trace metals; however, their role in sorption or mobilization of Hg in aquifers has been rarely analyzed. In this study, we investigated Hg chemistry and Hg sorption to HFO under changing redox conditions in a highly HgCl2-contaminated aquifer (up to 870μgL(-1) Hg). Results from aqueous and solid phase Hg measurements were compared to modeled (PHREEQC) data. Speciation analyses of dissolved mercury indicated that Hg(II) forms were reduced to Hg(0) under anoxic conditions, and adsorbed to or co-precipitated with HFO. Solid phase Hg thermo-desorption measurements revealed that between 55 and 93% of Hg bound to HFO was elemental Hg (Hg(0)). Hg concentrations in precipitates reached more than 4 weight %, up to 7000 times higher than predicted by geochemical models that do not consider unspecific sorption to and co-precipitation of elemental Hg with HFO. The observed process of Hg(II) reduction and Hg(0) formation, and its retention and co-precipitation by HFO is thought to be crucial in HgCl2-contaminated aquifers with variable redox-conditions regarding the related decrease in Hg solubility (factor of ~10(6)), and retention of Hg in the aquifer. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Enhancement of chitosan-graphene oxide SPR sensor with a multi-metallic layers of Au–Ag–Au nanostructure for lead(II) ion detection

    Energy Technology Data Exchange (ETDEWEB)

    Kamaruddin, Nur Hasiba [Department of Electric, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Bakar, Ahmad Ashrif A., E-mail: ashrif@ukm.edu.my [Department of Electric, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Yaacob, Mohd Hanif; Mahdi, Mohd Adzir [Wireless and Photonic Network Research Centre, Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Zan, Mohd Saiful Dzulkefly [Department of Electric, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Shaari, Sahbudin [Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2016-01-15

    Highlights: • Tri-metallic Au–Ag–Au CS-GO SPR sensor was fabricated for the first time. • The tri-metallic nanostructure provided an enhanced evanescent field. • Successful functionalization of the CS-GO sensing layer. • Superior performance for lead(II) ion detection. - Abstract: We demonstrate the enhancement of surface plasmon resonance (SPR) technique by implementing a multi-metallic layers of Au–Ag–Au nanostructure in the chitosan-graphene oxide (CS-GO) SPR sensor for lead(II) ion detection. The performance of the sensor is analyzed via SPR measurements, from which the sensitivity, signal-to-noise ratio and repeatability are determined. The nanostructure layers are characterized using field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). We showed that the proposed structure has increased the shift in the SPR angle up to 3.5° within the range of 0.1–1 ppm due to the enhanced evanescent field at the sensing layer-analyte interface. This sensor also exhibits great repeatability which benefits from the stable multi-metallic nanostructure. The SNR value of 0.92 for 5 ppm lead(II) ion solution and reasonable linearity range up to that concentration shows that the tri-metallic CS-GO SPR sensor gives a good response towards the lead(II) ion solution. The CS-GO SPR sensor is also sensitive to at least a 10{sup −5} change in the refractive index. The results prove that our proposed tri-metallic CS-GO SPR sensor demonstrates a strong performance and reliability for lead(II) ion detection in accordance with the standardized lead safety level for wastewater.

  9. A GMOS-N IFU study of the central H II region in the blue compact dwarf galaxy NGC 4449: kinematics, nebular metallicity and star formation

    Science.gov (United States)

    Kumari, Nimisha; James, Bethan L.; Irwin, Mike J.

    2017-10-01

    We use integral field spectroscopic (IFS) observations from the Gemini Multi-Object Spectrograph North (GMOS-N) to study the central H II region in a nearby blue compact dwarf (BCD) galaxy NGC 4449. The IFS data enable us to explore the variation of physical and chemical conditions of the star-forming region and the surrounding gas on spatial scales as small as 5.5 pc. Our kinematical analysis shows possible signatures of shock ionization and shell structures in the surroundings of the star-forming region. The metallicity maps of the region, created using direct Te and indirect strong line methods (R23, O3N2 and N2), do not show any chemical variation. From the integrated spectrum of the central H II region, we find a metallicity of 12 + log(O/H) = 7.88 ± 0.14 ({˜ }0.15^{+0.06}_{-0.04} Z⊙) using the direct method. Comparing the central H II region metallicity derived here with those of H II regions throughout this galaxy from previous studies, we find evidence of increasing metallicity with distance from the central nucleus. Such chemical inhomogeneities can be due to several mechanisms, including gas loss via supernova blowout, galactic winds or metal-poor gas accretion. However, we find that the localized area of decreased metallicity aligns spatially with the peak of star-forming activity in the galaxy, suggesting that gas accretion may be at play here. Spatially resolved IFS data for the entire galaxy are required to confirm the metallicity inhomogeneity found in this study and determine its possible cause.

  10. A NEW SCALING RELATION FOR H II REGIONS IN SPIRAL GALAXIES: UNVEILING THE TRUE NATURE OF THE MASS-METALLICITY RELATION

    International Nuclear Information System (INIS)

    Rosales-Ortega, F. F.; Díaz, A. I.; Sánchez, S. F.; Iglesias-Páramo, J.; Vílchez, J. M.; Mast, D.; Bland-Hawthorn, J.; Husemann, B.

    2012-01-01

    We demonstrate the existence of a local mass, metallicity, star formation relation using spatially resolved optical spectroscopy of H II regions in the local universe. One of the projections of this distribution—the local mass-metallicity relation—extends over a wide range in this parameter space: three orders of magnitude in mass and a factor of eight in metallicity. We explain the new relation as the combined effect of the differential distributions of mass and metallicity in the disks of galaxies, and a selective star formation efficiency. We use this local relation to reproduce—with a noticeable agreement—the mass-metallicity relation seen in galaxies, and conclude that the latter is a scale-up integrated effect of a local relation, supporting the inside-out growth and downsizing scenarios of galaxy evolution.

  11. A NEW SCALING RELATION FOR H II REGIONS IN SPIRAL GALAXIES: UNVEILING THE TRUE NATURE OF THE MASS-METALLICITY RELATION

    Energy Technology Data Exchange (ETDEWEB)

    Rosales-Ortega, F. F.; Diaz, A. I. [Departamento de Fisica Teorica, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Sanchez, S. F.; Iglesias-Paramo, J.; Vilchez, J. M.; Mast, D. [Instituto de Astrofisica de Andalucia (CSIC), Camino Bajo de Huetor s/n, Aptdo. 3004, E-18080 Granada (Spain); Bland-Hawthorn, J. [Sydney Institute for Astronomy, School of Physics A28, University of Sydney, NSW 2006 (Australia); Husemann, B., E-mail: frosales@cantab.net [Leibniz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)

    2012-09-10

    We demonstrate the existence of a local mass, metallicity, star formation relation using spatially resolved optical spectroscopy of H II regions in the local universe. One of the projections of this distribution-the local mass-metallicity relation-extends over a wide range in this parameter space: three orders of magnitude in mass and a factor of eight in metallicity. We explain the new relation as the combined effect of the differential distributions of mass and metallicity in the disks of galaxies, and a selective star formation efficiency. We use this local relation to reproduce-with a noticeable agreement-the mass-metallicity relation seen in galaxies, and conclude that the latter is a scale-up integrated effect of a local relation, supporting the inside-out growth and downsizing scenarios of galaxy evolution.

  12. Structures and Spectroscopy Studies of Two M(II-Phosphonate Coordination Polymers Based on Alkaline Earth Metals (M = Ba, Mg

    Directory of Open Access Journals (Sweden)

    Kui-Rong Ma

    2013-01-01

    Full Text Available The two examples of alkaline-earth M(II-phosphonate coordination polymers, [Ba2(L(H2O9]·3H2O (1 and [Mg1.5(H2O9]·(L-H21.5·6H2O (2 (H4L = H2O3PCH2N(C4H8NCH2PO3H2, N,N′-piperazinebis(methylenephosphonic acid, (L-H2 = O3PH2CHN(C4H8NHCH2PO3 have been hydrothermally synthesized and characterized by elemental analysis, FT-IR, PXRD, TG-DSC, and single-crystal X-ray diffraction. Compound 1 possesses a 2D inorganic-organic alternate arrangement layer structure built from 1D inorganic chains through the piperazine bridge, in which the ligand L−4 shows two types of coordination modes reported rarely at the same time. In 1, both crystallographic distinct Ba(1 and Ba(2 ions adopt 8-coordination two caps and 9-coordination three caps triangular prism geometry structures, respectively. Compound 2 possesses a zero-dimensional mononuclear structure with two crystallographic distinct Mg(II ions. Free metal cations   [MgO6]n2+ and uncoordinated anions (L-H2n2- are joined together by static electric force. Results of photoluminescent measurement indicate three main emission bands centered at 300 nm, 378.5 nm, and 433 nm for 1 and 302 nm, 378 nm, and 434.5 nm for 2 (λex=235 nm, respectively. The high energy emissions could be derived from the intraligand π∗-n transition stations of H4L (310 nm and 382 nm, λex=235 nm, while the low energy emission (>400 nm of 1-2 may be due to the coordination effect with metal(II ions.

  13. A quasi-stationary numerical model of atomized metal droplets, II: Prediction and assessment

    DEFF Research Database (Denmark)

    Pryds, Nini H.; Hattel, Jesper Henri; Thorborg, Jesper

    1999-01-01

    been illustrated.A comparison between the numerical model and the experimental results shows an excellent agreement and demonstrates the validity of the present model, e.g. the calculated gas temperature which has an important influence on the droplet solidification behaviour as well as the calculated......A new model which extends previous studies and includes the interaction between enveloping gas and an array of droplets has been developed and presented in a previous paper. The model incorporates the probability density function of atomized metallic droplets into the heat transfer equations....... The main thrust of the model is that the gas temperature was not predetermined and calculated empirically but calculated numerically based on heat balance consideration. In this paper, the accuracy of the numerical model and the applicability of the model as a predictive tool have been investigated...

  14. Removal of lead (II) from metal plating effluents using sludge based activated carbon as adsorbent.

    Science.gov (United States)

    Raju, P; Saseetharan, M K

    2010-01-01

    A novel adsorbent was prepared from waste sludge obtained from a sugar mill for removing heavy metals from industrial wastewater. The adsorption studies were carried out in batch and continuous modes for both sugar mill sludge based carbon and commercial carbon. In batch studies, experiments were conducted at ambient temperature to assess the influence of the parameters such as pH, adsorbent dose, contact time and equilibrium concentration. Adsorption data for the prepared carbon was found to satisfy both the Freundlich and Langmuir isotherms. Column studies were carried out to delineate the effect of varying depth of carbon at constant flow rate. The breakthrough curves were drawn to establish the mechanism. The result shows that the sludge based activated carbon can be used as an alternative for commercial carbon.

  15. A treatise on benzimidazole based Schiff base metal(II) complexes accentuating their biological efficacy: Spectroscopic evaluation of DNA interactions, DNA cleavage and antimicrobial screening

    Energy Technology Data Exchange (ETDEWEB)

    Kumaravel, Ganesan; Raman, Natarajan, E-mail: ramchem1964@gmail.com

    2017-01-01

    Two novel imidazole derived Schiff bases, (Z)-1-(1H-benzo[d]imidazol-2-yl)-N-benzylidenemethanamine (L{sup 1}) and 1-(1H-benzo[d]imidazol-2-yl)-N-(4-nitrobenzylidene) methanamine, and a series of their transition metal complexes of the types [M(L{sup 1}){sub 2}]Cl{sub 2} and [M(L{sup 2}){sub 2}]Cl{sub 2} where, M = Cu(II), Ni(II), Co(II) and Zn(II) have been designed and synthesized. These compounds were characterized by various spectral and physicochemical data. UV–Vis, magnetic susceptibility and molar conductivity data indicate that all the complexes adopt square planar geometry. The EPR spectral data of the Cu(II) complexes have provided supportive evidence to the conclusion derived on the basis of electronic absorption and magnetic moment values. Moreover, the interaction of complexes with DNA via intercalation has been explored by absorption, fluorescence spectroscopy, cyclic voltammetry, viscosity and circular dichroism. Agarose gel electrophoresis technique reveals that the complexes are good metallonucleases. All the compounds have relatively high antibacterial and antifungal potencies. Among the metal complexes, Cu(II) complexes exhibit higher efficacy against all the pathogens. - Highlights: • Synthesis of new and efficient benzimidazole based DNA targeting complexes • Synthesis of efficient metallointercalators • Excellent DNA exploiting ability of Cu(II) complexes • Efficient antimicrobial agents against various pathogens.

  16. Next Generation Metallic Iron Nodule Technology in Electric Arc Steelmaking - Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Donald R. Fosnacht; Iwao Iwasaki; Richard F. Kiesel; David J. Englund; David W. Hendrickson; Rodney L. Bleifuss

    2010-12-22

    The current trend in the steel industry is a gradual decline in conventional steelmaking from taconite pellets in blast furnaces, and an increasing number of alternative processes using metallic scrap iron, pig iron and metallized iron ore products. Currently, iron ores from Minnesota and Michigan are pelletized and shipped to the lower Great Lakes ports as blast furnace feed. The existing transportation system and infrastructure is geared to handling these bulk materials. In order to expand the opportunities for the existing iron ore mines beyond their blast furnace customer base, a new material is needed to satisfy the needs of the emerging steel industry while utilizing the existing infrastructure and materials handling. A recent commercial installation employing Kobe Steel’s ITmk3 process, was installed in Northeastern Minnesota. The basic process uses a moving hearth furnace to directly reduce iron oxides to metallic iron from a mixture of iron ore, coals and additives. The resulting products can be shipped using the existing infrastructure for use in various steelmaking processes. The technology reportedly saves energy by 30% over the current integrated steelmaking process and reduces emissions by more than 40%. A similar large-scale pilot plant campaign is also currently in progress using JFE Steel’s Hi-QIP process in Japan. The objective of this proposal is to build upon and improve the technology demonstrated by Kobe Steel and JFE, by further reducing cost, improving quality and creating added incentive for commercial development. This project expands previous research conducted at the University of Minnesota Duluth’s Natural Resources Research Institute and that reported by Kobe and JFE Steel. Three major issues have been identified and are addressed in this project for producing high-quality nodular reduced iron (NRI) at low cost: (1) reduce the processing temperature, (2) control the furnace gas atmosphere over the NRI, and (3) effectively use sub

  17. Effect on the Inhibitory Activity of Potential Microbes on the Complexation of Methyl Anthranilate Derived Hydrazide with Cu, Ni and Zn (II) Metal Ions

    International Nuclear Information System (INIS)

    Ikram, M.; Rehman, S.; Khan, K.

    2013-01-01

    The hydrazide ligand 2-amino-(N-aminobezoyl)benzohydrazide (ABH) have been synthesized and characterized by 1H-NMR, 13C-NMR, ES+-MS, elemental analyses and infrared studies. The ligand was complexed with Ni(II), Cu(II) and Zn(II) metal ions and were characterized by analytical and spectroscopic methods including elemental analyses, ES+-MS, conductance, infrared, UV-Visible and magnetic susceptibilities studies. Infrared spectra show that the ligand form complexes through -NH2 and carbonyl moieties, the elemental studies suggested the M(ABH)X2 composition of the coordination compounds. The synthesized complexes were studied for their biological activities against gram negative bacteria including Escherichia coli, Salmonella typhi, Enterobacter aerogenes, Proteus vulgaris, Pseudomonas aeruginosa, Gram positive bacterial strains like Staphylococcus aureus and fungus like Candida albican. These activities show that the metal complexes are more active to the tested microbes as compared to neat ligand. (author)

  18. Exploring 3D non-interpenetrated metal-organic framework with malonate-bridged Co(II) coordination polymer: structural elucidation and theoretical study

    Science.gov (United States)

    Hossain, Anowar; Mandal, Tripti; Mitra, Monojit; Manna, Prankrishna; Bauzá, Antonio; Frontera, Antonio; Seth, Saikat Kumar; Mukhopadhyay, Subrata

    2017-12-01

    A Co(II)-based coordination polymer with tetranuclear cobalt(II)-malonate cluster has been easily generated by aqueous medium self-assembly from Cobalt(II) chloride hexahydrate and malonic acid. The structure exhibits a non-interpenetrating, highly undulating two-dimensional (2D) bi-layer network with (4,4) topology. The crystal structure is composed of infinite interdigitated 2D metal-organic bi-layers which extended to an intricate 3D framework through the interbilayer hydrogen bonds. We have studied energetically by means of Density Functional Theory (DFT) calculations the H-bonding interactions that connect the 2D metal-organic bi-layers. The finite theoretical models have been used to compute conventional O‒H•••O and unconventional C‒H•••O interactions which plays a key role to build 3D architecture.

  19. Elastic interactions between hydrogen atoms in metals. II. Elastic interaction energies

    International Nuclear Information System (INIS)

    Shirley, A.I.; Hall, C.K.

    1986-01-01

    The fully harmonic lattice approximation derived in a previous paper is used to calculate the elastic interaction energies in the niobium-hydrogen system. The permanent-direct, permanent-indirect, induced-direct, and induced-indirect forces calculated previously each give rise to a corresponding elastic interaction between hydrogen atoms. The latter three interactions have three- and four-body terms in addition to the usual two-body terms. These quantities are calculated and compared with the corresponding two-body permanent elastic interactions obtained in the harmonic-approximation treatment of Horner and Wagner. The results show that the total induced elastic energy is approximately (1/3) the size of the total permanent elastic energy and opposite to it in sign. The total elastic energy due to three-body interactions is approximately (1/4) the size of the total two-body elastic energy, while the total four-body elastic energy is approximately 5% of the total two-body energy. These additional elastic energies are expected to have a profound effect on the thermodynamic and phase-change behavior of a metal hydride

  20. Application of Local Adsorbant From Southeast Sulawesi Clay Immobilized Saccharomyces Cerevisiae Bread’s Yeast Biomass for Adsorption Of Mn(Ii) Metal Ion

    Science.gov (United States)

    R, Halimahtussaddiyah; Mashuni; Budiarni

    2017-05-01

    Southeast Sulawesi has a great stock of clay. It is probably to use as a source of adsorbent. The adsorbent capacity of clay can be largered with teratment using bread’s yeast as biomass. At this research, study of analysis adsorption of Mn(II) metal ion on clay immobilized Saccharomyces cerevisiae bread’s yeast biomass adsorbent has been conducted. The aims of this research were to determine the effects of contact time, pH and concentration of Mn(II) metal ion and to determine the adsorption capacity of clay immobilized S. cerevisiae biomass for adsorbtion of Mn(II) metal ion. Activated clay was synthesized by reaction of clay with KMnO4, H2SO4 and HCl. S. cerevisiae biomass was result by bread’s yeast mashed. Immobilization of S. cerevisiae biomass into clay was done by mixing of ratio of S. cerevisiae bread’s yeast biomass and clay equal to 1:3 (mass of biomassa : mass of clay). The adsorption capacity was determined by using Freundlich and Langmuir adsorption isoterms. The results of FTIR spectrums showed that the functional groups of clay immobilized S. cerevisiae biomass were Si-OH (wave number 1643 cm-1), Si-O-Si (wave number 1033 cm-1), N-H (wave number 2337 cm-1), O-H (wave number 3441cm-1), and C-H (wave number 2931 cm-1). The result of adsorption capacity from Mn(II) metal ion of contact time optimum 120 minutes, pH optimun at 7 and concentration optimum 50 mg/L were 1,816 mg/g; 0,509 mg/g and 2,624mg/g respectively. The adsorption capacity of Mn(II) metal ion with ratio 1:3 (biomass : clay) was 0,1045 mg/g. Type of isothermal adsorption followed the Freunlich adsorption.

  1. Degradation of the metal-cyano complex tetracyanonickelate (II) by Fusarium oxysporum N-10.

    Science.gov (United States)

    Yanase, H; Sakamoto, A; Okamoto, K; Kita, K; Sato, Y

    2000-03-01

    A fungus with the ability to utilize a metalcyano compound, tetracyanonickelate (II) ¿K2[Ni (CN)4]; TCN¿, as its sole source of nitrogen was isolated from soil and identified as Fusarium oxysporum N-10. Both intact mycelia and cell-free extract of the strain catalyzed hydrolysis of TCN to formate and ammonia and produced formamide as an intermediate, thereby indicating that a hydratase and an amidase sequentially participated in the degradation of TCN. The enzyme catalyzing the hydration of TCN was purified approximately ten-fold from the cell-free extract of strain N-10 with a yield of 29%. The molecular mass of the active enzyme was estimated to be 160 kDa. The enzyme appears to exist as a homotetramer, each subunit having a molecular mass of 40 kDa. The enzyme also catalyzed the hydration of KCN, with a cyanide-hydrating activity 2 x 10(4) times greater than for TCN. The kinetic parameters for TCN and KCN indicated that hydratase isolated from F. oxysporum was a cyanide hydratase able to utilize a broad range of cyano compounds and nitriles as substrates.

  2. Fluorometric determination of aluminium (III) and cadmium (II) by solvent extraction of the ternary complex composed of metal ion, 8-hydroxy-5-quinolinesulfonic acid, and methyltrioctylammonium ion

    International Nuclear Information System (INIS)

    Kondoh, Yukihiro; Kataoka, Masamitsu; Kambara, Tomihito

    1982-01-01

    A fluorometric micro determination of aluminium (III) and cadmium (II) using the formation of metal-8-hydroxy-5-quinolinesulfonic acid-capriquat (methyltrioctylammonium) ternary complex is described. These complexes are easily extracted into chloroform phase and the extract emits a strong fluorescence. Spectra of aluminium (III) and cadmium (II) ternary complexes have the excitation maximum at 396 nm and 400 nm, and emission maximum at 501 nm and 524 nm, respectively. Fluorescence intensity of the aluminium (III) and cadmium (II) ternary complexes extracted into chloroform showed the constant and maximum values in the pH range of aqueous phase from 5.3 to 8.5 and 8.1 to 8.5, respectively. The calibration curves for aluminium (III) and cadmium (II) show good proportionality int the concentration range from 0.5 to 5.0 and 1.0 to 50.0 μg, respectively. The relative standard deviation observed with four measurements was found to be 1.8% for 0.5 μg of aluminium (III) and 1.1% for 10.0 μg of cadmium (II). The effect of diverse ions is studied and a 25-fold amount of Cu(II), Ni(II), Fe(II), Fe(III) in weight gave errors, however, the interferences were easily eliminated by the addition of appropriate masking agent. In the determination of cadmium (II), an equal amount of Co(II), Ni(II), Mn(II), Fe(III) and twice amount of Al(III) gave negative errors, however, the interference of Fe(III) and Al(III) were also eliminated as above. (author)

  3. Spin Forming Aluminum Crew Module (CM) Metallic Aft Pressure Vessel Bulkhead (APVBH) - Phase II

    Science.gov (United States)

    Hoffman, Eric K.; Domack, Marcia S.; Torres, Pablo D.; McGill, Preston B.; Tayon, Wesley A.; Bennett, Jay E.; Murphy, Joseph T.

    2015-01-01

    The principal focus of this project was to assist the Multi-Purpose Crew Vehicle (MPCV) Program in developing a spin forming fabrication process for manufacture of the Orion crew module (CM) aft pressure vessel bulkhead. The spin forming process will enable a single piece aluminum (Al) alloy 2219 aft bulkhead resulting in the elimination of the current multiple piece welded construction, simplify CM fabrication, and lead to an enhanced design. Phase I (NASA TM-2014-218163 (1)) of this assessment explored spin forming the single-piece CM forward pressure vessel bulkhead. The Orion MPCV Program and Lockheed Martin (LM) recently made two critical decisions relative to the NESC Phase I work scope: (1) LM selected the spin forming process to manufacture a single-piece aft bulkhead for the Orion CM, and (2) the aft bulkhead will be manufactured from Al 2219. Based on the Program's new emphasis related to the spin forming process, the NESC was asked to conduct a Phase II assessment to assist in the LM manufacture of the aft bulkhead and to conduct a feasibility study into spin forming the Orion CM cone. This activity was approved on June 19, 2013. Dr. Robert Piascik, NASA Technical Fellow for Materials at the Langley Research Center (LaRC), was selected to lead this assessment. The project plan was approved by the NASA Engineering and Safety Center (NESC) Review Board (NRB) on July 18, 2013. The primary stakeholders for this assessment were the NASA and LM MPCV Program offices. Additional benefactors are commercial launch providers developing CM concepts.

  4. River sediment metal and nutrient variations along an urban-agriculture gradient in an arid austral landscape: implications for environmental health.

    Science.gov (United States)

    Dalu, Tatenda; Wasserman, Ryan J; Wu, Qihang; Froneman, William P; Weyl, Olaf L F

    2018-01-01

    The effect of metals on environmental health is well documented and monitoring these and other pollutants is considered an important part of environmental management. Developing countries are yet to fully appreciate the direct impacts of pollution on aquatic ecosystems and as such, information on pollution dynamics is scant. Here, we assessed the temporal and spatial dynamics of stream sediment metal and nutrient concentrations using contaminant indices (e.g. enrichment factors, pollution load and toxic risk indices) in an arid temperate environment over the wet and dry seasons. The mean sediment nutrient, organic matter and metal concentration were highest during the dry season, with high values being observed for the urban environment. Sediment contaminant assessment scores indicated that during the wet season, the sediment quality was acceptable, but not so during the dry season. The dry season had low to moderate levels of enrichment for metals B, Cu, Cr, Fe, Mg, K and Zn. Overall, applying the sediment pollution load index highlighted poor quality river sediment along the length of the river. Toxic risk index indicated that most sites posed no toxic risk. The results of this study highlighted that river discharge plays a major role in structuring temporal differences in sediment quality. It was also evident that infrastructure degradation was likely contributing to the observed state of the river quality. The study contributes to our understanding of pollution dynamics in arid temperate landscapes where vast temporal differences in base flow characterise the riverscape. Such information is further useful for contrasting sediment pollution dynamics in aquatic environments with other climatic regions.

  5. Four Mixed-Ligand Zn(II Three-Dimensional Metal-Organic Frameworks: Synthesis, Structural Diversity, and Photoluminescent Property

    Directory of Open Access Journals (Sweden)

    Chih-Chieh Wang

    2017-11-01

    Full Text Available Assemblies of four three-dimensional (3D mixed-ligand coordination polymers (CPs having formulas, {[Zn2(bdc2(4-bpdh]·C2H5OH·2H2O}n (1, [Zn(bdc(4-bpdh]n (2, {[Zn2(bdc2(4-bpdh2]·(4-bpdh}n (3, and {[Zn(bdc(4-bpdh]·C2H5OH}n (4 (bdc2− = dianion of 1,4-benzenedicarboxylic acid, 4-bpdh = 2,5-bis(4-pyridyl-3,4-diaza-2,4-hexadiene have been synthesized and structurally characterized by single-crystal X-ray diffraction method. Structural determination reveals that the coordination numbers (geometry of Zn(II ions in 1, 2, 3, and 4 are five (distorted square-pyramidal (SP, six (distorted octahedral (Oh, five (trigonal-bipyramidal (TBP, and four (tetrahedral (Td, respectively, and are bridged by 4-bpdh with bis-monodentate coordination mode and bdc2− ligands with bis-bidentate in 1, chelating/bidentate in 2, bis-monodentate and bis-bidentate in 3, and bis-monodentate in 4, to generate two-fold interpenetrating 3D cube-like metal-organic framework (MOF with pcu topology, non-interpenetrating 3D MOF, two-fold interpenetrating 3D rectangular-box-like MOF with pcu topology and five-fold interpenetrating diamondoid-like MOF with dia topology, respectively. These different intriguing architectures indicate that the coordination numbers and geometries of Zn(II ions, coordination modes of bdc2− ligand, and guest molecules play important roles in the construction of MOFs and the formation of the structural topologies and interpenetrations. Thermal stabilities, and photoluminescence study of 1–4 were also studied in detail. The complexes exhibit ligands based photoluminescence properties at room temperature.

  6. Harnessing the bio-mineralization ability of urease producing Serratia marcescens and Enterobacter cloacae EMB19 for remediation of heavy metal cadmium (II).

    Science.gov (United States)

    Bhattacharya, Amrik; Naik, S N; Khare, S K

    2018-06-01

    In the present study, urease positive Serratia marcescens (NCIM2919) and Enterobacter cloacae EMB19 (MTCC10649) were individually evaluated for remediation of cadmium (II) using ureolysis-induced calcium carbonate precipitation. Both the cultures were observed to efficiently remove cadmium from the media through co-precipitation of Cd (II) and Ca (II). S. marcescens and E. cloacae EMB19, respectively showed 96 and 98% removal of initial 5.0 mg L -1 soluble Cd (II) from the urea and CaCl 2 laden media at 96 h of incubation period. At higher Cd (II) concentrations of 10 and 15 mg L -1 , cadmium removal efficiency was much higher in case of E. cloacae EMB19 compared to S. marcescens. In-vitro cadmium (II) remediation study using urease containing cell-free culture supernatant of S. marcescens and E. cloacae EMB19 showed respective 98 and 53% removal of initial 50 mg L -1  Cd (II) from the reaction mixtures in co-presence of Ca (II). While in sole presence of Cd (II), only 16 and 8% removal of Cd (II) were detected for S. marcescens and E. cloacae EMB19, respectively. The elemental analysis of the co-precipitated mineral products using Energy Dispersive X-ray spectroscopy (EDX) clearly showed the prevalence of Ca and Cd ions. The morphology Cd-Ca composites formed with respect to both the cultures were observed to be of different shape and size as revealed through Scanning Electron Microscopy (SEM). Entire study hence comes out with a sustainable bioremediation option which could be effectively used to tackle Cd (II) or other heavy metal pollution. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Metal-poor dwarf galaxies in the SIGRID galaxy sample. II. The electron temperature-abundance calibration and the parameters that affect it

    Energy Technology Data Exchange (ETDEWEB)

    Nicholls, David C.; Dopita, Michael A.; Sutherland, Ralph S.; Jerjen, Helmut; Kewley, Lisa J., E-mail: David.Nicholls@anu.edu.au [Research School of Astronomy and Astrophysics, Australian National University, Cotter Rd., Weston ACT 2611 (Australia)

    2014-07-20

    In this paper, we use the Mappings photoionization code to explore the physical parameters that impact on the measurement of electron temperature and abundance in H II regions. In our previous paper, we presented observations and measurements of physical properties from the spectra of 17 H II regions in 14 isolated dwarf irregular galaxies from the SIGRID sample. Here, we analyze these observations further, together with three additional published data sets. We explore the effects of optical thickness, electron density, ionization parameter, ionization source, and non-equilibrium effects on the relation between electron temperature and metallicity. We present a standard model that fits the observed data remarkably well at metallicities between one-tenth and 1 solar. We investigate the effects of optically thin H II regions, and show that they can have a considerable effect on the measured electron temperature, and that there is evidence that some of the observed objects are optically thin. We look at the role of the ionization parameter and find that lower ionization parameter values give better fits at higher oxygen abundance. We show that higher pressures combined with low optical depth, and also κ electron energy distributions at low κ values, can generate the apparent high electron temperatures in low-metallicity H II regions, and that the former provides the better fit to observations. We examine the effects of these parameters on the strong line diagnostic methods. We extend this to three-dimensional diagnostic grids to confirm how well the observations are described by the grids.

  8. A Cd(II)-based metal-organic framework as a luminance sensor to nitrobenzene and Tb(III) ion.

    Science.gov (United States)

    Qu, Xiang-Long; Gui, Di; Zheng, Xiao-Li; Li, Rui; Han, Hong-Liang; Li, Xia; Li, Pei-Zhou

    2016-04-28

    A Cd(II)-based metal-organic framework, [Cd2(DPDC)2(BTB)]∞ (Cd-MOF, DPDC = 2,2'-diphenyldicarboxylate and BTB = 1,4-bis(1,2,4-triazol-1-yl)butane) was successfully constructed via a hydrothermal reaction. Structural analysis shows that the synthesized Cd-MOF is a three-dimensional (3D) architecture crystallized in the hexagonal system with a chiral space group P61. Powder X-ray diffraction experiments and thermogravimetric analysis reveal that the constructed Cd-MOF has a high chemical and thermal stability. A study of additional mechanical properties indicates that it exhibits a moderate stiffness with the average values of Young's modulus (E) and H as 11.3(2) and 0.9(7) GPa, respectively. The luminescence properties of the Cd-MOF were further studied. The result shows that it could be an effective sensor to the organic nitrobenzene molecule via a strong quenching effect, and also to the inorganic Tb(III) ion by a strong green emission effect. Moreover, when loading bimetal ions (Eu(III) and Tb(III) into the Cd-MOF/methanol suspension, tunable visible luminescence can also be achieved by carefully adjusting the excitation wavelengths.

  9. Contamination smoke: a simulation of heavy metal containing aerosols from fires in plutonium glove boxes: part II

    International Nuclear Information System (INIS)

    Buijs, K.; Chavane de Dalmassy, B.; Baumgaertner, E.

    1992-01-01

    The study of the dispersion of plutonium bearing aerosols during glove box fires on a laboratory scale has been, in part I of this work, focussed on fires of polymethylmethacrylate (PMMA - the major glove box construction material) whose surfaces were contaminated with cerium-europium oxide powder as a substitute for plutonium-uranium oxide. The present part II completes the study with comparative fire experiments involving contaminated samples of various glove box materials burning in or exposed to the flames of the standardized 0.6 MW fire source previously developed. Beyond spreading of the Ce-Eu-oxide powder as mentioned above, the other important surface contamination process is used, i.e. deposition and subsequent drying of droplets from acid cerium-europium solutions. It is shown that, among the tested materials, and with the exception of synthetic glove rubber, burning PMMA spreads the most radioactive contamination. On the other hand, this potential risk is much lower for fires involving materials contaminated from solution deposition than from powder or pellets. Attempts to measure the airborne contaminant particle sizes did not yield conclusive results. They suggest, however, that contamination from solutions leads to smaller heavy-metal containing aerosol particles than contamination with powder

  10. Ruthenium(ii)-polypyridyl zirconium(iv) metal-organic frameworks as a new class of sensitized solar cells.

    Science.gov (United States)

    Maza, W A; Haring, A J; Ahrenholtz, S R; Epley, C C; Lin, S Y; Morris, A J

    2016-01-01

    A series of Ru(ii)L 2 L' (L = 2,2'-bipyridyl, L' = 2,2'-bipyridine-5,5'-dicarboxylic acid), RuDCBPY, -containing zirconium(iv) coordination polymer thin films have been prepared as sensitizing materials for solar cell applications. These metal-organic framework (MOF) sensitized solar cells, MOFSCs, each are shown to generate photocurrent in response to simulated 1 sun illumination. Emission lifetime measurements indicate the excited state quenching of RuDCBPY at the MOF-TiO 2 interface is extremely efficient (>90%), presumably due to electron injection into TiO 2 . A mechanism is proposed in which RuDCBPY-centers photo-excited within the MOF-bulk undergo isotropic energy migration up to 25 nm from the point of origin. This work represents the first example in which a MOFSC is directly compared to the constituent dye adsorbed on TiO 2 (DSC). Importantly, the MOFSCs outperformed their RuDCBPY-TiO 2 DSC counterpart under the conditions used here and, thus, are solidified as promising solar cell platforms.

  11. Non-noble metal graphene oxide-copper (II) ions hybrid electrodes for electrocatalytic hydrogen evolution reaction

    KAUST Repository

    Muralikrishna, S.

    2015-08-25

    Non-noble metal and inexpensive graphene oxide-copper (II) ions (GO-Cu2+) hybrid catalysts have been explored for the hydrogen evolution reaction (HER). We were able to tune the binding abilities of GO toward the Cu2+ ions and hence their catalytic properties by altering the pH. We have utilized the oxygen functional moieties such as carboxylate, epoxide, and hydroxyl groups on the edge and basal planes of the GO for binding the Cu2+ ions through dative bonds. The GO-Cu2+ hybrid materials were characterized by cyclic voltammetry in sodium acetate buffer solution. The morphology of the hybrid GO-Cu2+ was characterized by atomic force microscopy. The GO-Cu2+ hybrid electrodes show good electrocatalytic activity for HER with low overpotential in acidic solution. The Tafel slope for the GO-Cu2+ hybrid electrode implies that the primary discharge step is the rate determining step and HER proceed with Volmer step. © 2015 American Institute of Chemical Engineers Environ Prog.

  12. An implicit tensorial gradient plasticity model - formulation and comparison with a scalar gradient model

    NARCIS (Netherlands)

    Poh, L.H.; Peerlings, R.H.J.; Geers, M.G.D.; Swaddiwudhipong, S.

    2011-01-01

    Many rate-independent models for metals utilize the gradient of effective plastic strain to capture size-dependent behavior. This enhancement, sometimes termed as "explicit" gradient formulation, requires higher-order tractions to be imposed on the evolving elasto-plastic boundary and the resulting

  13. Low-temperature CVD of iron, cobalt, and nickel nitride thin films from bis[di(tert-butyl)amido]metal(II) precursors and ammonia

    International Nuclear Information System (INIS)

    Cloud, Andrew N.; Abelson, John R.; Davis, Luke M.; Girolami, Gregory S.

    2014-01-01

    Thin films of late transition metal nitrides (where the metal is iron, cobalt, or nickel) are grown by low-pressure metalorganic chemical vapor deposition from bis[di(tert-butyl)amido]metal(II) precursors and ammonia. These metal nitrides are known to have useful mechanical and magnetic properties, but there are few thin film growth techniques to produce them based on a single precursor family. The authors report the deposition of metal nitride thin films below 300 °C from three recently synthesized M[N(t-Bu) 2 ] 2 precursors, where M = Fe, Co, and Ni, with growth onset as low as room temperature. Metal-rich phases are obtained with constant nitrogen content from growth onset to 200 °C over a range of feedstock partial pressures. Carbon contamination in the films is minimal for iron and cobalt nitride, but similar to the nitrogen concentration for nickel nitride. X-ray photoelectron spectroscopy indicates that the incorporated nitrogen is present as metal nitride, even for films grown at the reaction onset temperature. Deposition rates of up to 18 nm/min are observed. The film morphologies, growth rates, and compositions are consistent with a gas-phase transamination reaction that produces precursor species with high sticking coefficients and low surface mobilities

  14. A gel probe equilibrium sampler for measuring arsenic porewater profiles and sorption gradients in sediments: II. Field application to Haiwee reservoir sediment

    Science.gov (United States)

    Campbell, K.M.; Root, R.; O'Day, P. A.; Hering, J.G.

    2008-01-01

    Arsenic (As) geochemistry and sorption behavior were measured in As- and iron (Fe)-rich sediments of Haiwee Reservoir by deploying undoped (clear) polyacrylamide gels and hydrous ferric oxide (HFO)-doped gels in a gel probe equilibrium sampler, which is a novel technique for directly measuring the effects of porewater composition on As adsorption to Fe oxides phases in situ. Arsenic is deposited at the sediment surface as As(V) and is reduced to As(III) in the upper layers of the sediment (0-8 cm), but the reduction of As(V) does not cause mobilization into the porewater. Dissolved As and Fe concentrations increased at depth in the sediment column driven by the reductive dissolution of amorphous Fe(III) oxyhydroxides and conversion to a mixed Fe(II, III) green rust-type phase. Adsorption of As and phosphorous (P) onto HFO-doped gels was inhibited at intermediate depths (10-20 cm), possibly due to dissolved organic or inorganic carbon, indicating that dissolved As concentrations were at least partially controlled by porewater composition rather than surface site availability. In sediments that had been recently exposed to air, the region of sorption inhibition was not observed, suggesting that prior exposure to air affected the extent of reductive dissolution, porewater chemistry, and As adsorption behavior. Arsenic adsorption onto the HFO-doped gels increased at depths >20 cm, and the extent of adsorption was most likely controlled by the competitive effects of dissolved phosphate. Sediment As adsorption capacity appeared to be controlled by changes in porewater composition and competitive effects at shallower depths, and by reductive dissolution and availability of sorption sites at greater burial depths. ?? 2008 American Chemical Society.

  15. Efficient removal of cobalt(II) and strontium(II) metals from water using ethylene diamine tetra-acetic acid functionalized graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Amer, Hany; Moustafa, Wafaa M. [Nuclar Fuel Cycle Department, Nuclear and Radiological Regulatory Authority (NRRA), Naser City, Cairo (Egypt); Farghali, Ahmed A.; El Rouby, Waleed M.A. [Materials Science and Nanotechnology Department, Faculty of Postgraduate Studies for Advanced Sciences (PASA), Beni-Suef University (Egypt); Khalil, Waleed F. [Nuclar Fuel Cycle Department, Nuclear and Radiological Regulatory Authority (NRRA), Naser City, Cairo (Egypt); Materials Science and Nanotechnology Department, Faculty of Postgraduate Studies for Advanced Sciences (PASA), Beni-Suef University (Egypt)

    2017-12-04

    Graphene oxide (GO) with high specific surface area was prepared and functionalized with ethylene diamine tetra-acetic acid (EDTA). The as-prepared GO and the functionalized one (GO-EDTA) were characterized using high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and Raman spectroscopy. The as-prepared and EDTA functionalized GO were applied as adsorbent to remove strontium(II) and cobalt(II) from water. The results indicated that the prepared materials are efficient adsorbents for strontium(II) and cobalt(II) removal. The adsorption of Co{sup II} and Sr{sup II} under effects of contact time, temperature, and pH was investigated It is concluded that the maximum adsorption capacities of GO for Co{sup II} and Sr{sup II} were about 168 and 140 mg.g{sup -1}, whereas of GO-EDTA the values were about 197 and 158 mg.g{sup -1}, respectively. It is indicated that pH 6 and temperature 40 C are the best condition for Co{sup II} and Sr{sup II} removal from water. The application of Langmuir and Freundlich isotherms indicated that Langmuir isotherm is best fit for Co{sup II} and Sr{sup II} equilibrium adsorption. Adsorption kinetics were studied by applying pseudo first-order, pseudo second-order, and intraparticle diffusion models on the experimental data. The results proved that pseudo second-order model is the best represented adsorption kinetics. Appling the intraparticle diffusion regressions on the experimental data indicated that intraparticle diffusion involved in adsorption process, which was not the only rate-controlling step. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Development of metal fuel and study of construction materials (I-IV), Part II; Razvoj metalnog goriva i ispitivanje konstrukcionih materijala (I-VI deo); II deo

    Energy Technology Data Exchange (ETDEWEB)

    Mihajlovic, A [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

    1965-11-15

    The studies were devoted to problems related to application of metal uranium as fuel in heavy water reactors. Influence of thermal treatment on material texture and recrystallization of cast uranium was investigated. Structural changes of uranium alloys with molybdenum and niobium were tested during different heat treatments. A review of the possibilities for using metal uranium fuel in heavy water reactors is included.

  17. Crystal Structures and Characterizations of Bis(1-benzoyl methyl-benzotriazole-N3)dichoro Metal(II) Complex:[MCl2-(C6H4N3CH2COPh)2] [M=Zn(II), Co(II)

    Institute of Scientific and Technical Information of China (English)

    JIAN,Fang-Fang(建方方); SUN,Ping-Ping(孙萍萍); XIAO,Hai-Lian(肖海连); JIAO,Kui(焦奎)

    2004-01-01

    The structures of [MCl2(C6H4N3CH2COPh)2] [M=Zn(II) (1), Co(II) (2)] have been determined by X-ray crystallography. They were characterized by elemental analysis, IR spectrum, electronic spectrum and thermogravimetric-differential thermal analysis. They all crystallize in the triclinic system, space group Pī, with lattice parameters a=0.9449(2) nm, b=1.1291(2) nm, c=1.3637(3) nm, α=111.70(3)°, β=94.33(3)°, γ=90.97(3), Z=2 for compound 1; a=0.9437(2) nm, b=1.1277(2) nm, c=1.3650(3) nm, α=111.76(3)°, β=94.50(3)°, γ=90.80(3)°, Z=2 for compound 2. The metal ions are all coordinated by two Cl- anions and two nitrogen atoms of 1-benzoylmethyl-benzotriazole ligands, forming the distorted tetrahedral geometry. The Zn-Cl and Zn-N bond lengths are 0.2209(2), 0.2210(2) nm and 0.2059(4), 0.2067(4) nm, respectively. The Co-Cl and Co-N bond lengths are 0.2215(2), 0.2222(2) nm and 0.2028(5), 0.2045(5) nm, respectively. The thermogravimetric (TG) data indicate that they are nearly similar in TG curve, and there are not structural transitions in the two compounds. They all have a high thermal stability. But, there is little difference in DTG (differential thermogravimetric) curves of those two compounds. Elemental analysis, electronic and IR spectra are in agreement with the structural data.

  18. Synthesis and characterization of near-IR absorbing metal-free and zinc(II phthalocyanines modified with aromatic azo groups

    Directory of Open Access Journals (Sweden)

    Mukaddes Özçeşmeci

    2015-05-01

    Full Text Available Metal-free and zinc(II phthalocyanine complexes bearing peripheral (E-4-((2-hydroxynaphthalen-1-yldiazenyl units have been synthesized. Novel phthalonitrile derivative required for the preparation of phthalocyanine complexes was prepared by coupling 4-aminophthalonitrile and 2-naphthol. The structures of these new compounds were characterized by using elemental analyses, proton nuclear magnetic resonance, fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, fluorescence spectroscopy and mass spectrometry. In the UV-Vis spectra a broad absorption band appears for phthalocyanine complexes at around 450–500 nm resulting from azo-group introduced onto the phthalocyanine ring. The photophysical properties of metal-free and zinc(II phthalocyanines were studied in tetrahydrofuran.

  19. Copper(II) and zinc(II) as metal-carboxylate coordination complexes based on (1-methyl-1H-benzo[d]imidazol-2-yl) methanol derivative: Synthesis, crystal structure, spectroscopy, DFT calculations and antioxidant activity

    Science.gov (United States)

    Benhassine, Anfel; Boulebd, Houssem; Anak, Barkahem; Bouraiou, Abdelmalek; Bouacida, Sofiane; Bencharif, Mustapha; Belfaitah, Ali

    2018-05-01

    This work presents a combined experimental and theoretical study of two new metal-carboxylate coordination compounds. These complexes were prepared from (1-methyl-1H-benzimidazol-2-yl)methanol under mild conditions. The structures of the prepared compounds were characterized by single-crystal X-ray analysis, FTIR and UV-Vis spectroscopy. In the Cupper complex, the Cu(II) ion is coordinated by two ligands, which act as bidentate chelator through the non-substituted N and O atoms, and two carboxylicg oxygen atoms, displaying a hexa-coordinated compound in a distorted octahedral geometry, while in the Zinc complex the ligand is ligated to the Zn(II) ion in monodentate fashion through the N atom, and the metal ion is also bonded to carboxylic oxygen atoms. The tetra-coordinated compound displays a distorted tetrahedral shape. The density functional theory calculations are carried out for the determination of the optimized structures. The electronic transitions and fundamental vibrational wave numbers are calculated and are in good agreement with experimental. In addition, the ligand and its Cu(II) and Zn(II) complexes were screened and evaluated for their potential as DPPH radical scavenger.

  20. Revisiting the radial abundance gradients of nitrogen and oxygen of the Milky Way

    Science.gov (United States)

    Esteban, C.; García-Rojas, J.

    2018-05-01

    We present spectra obtained with the 10.4 m Gran Telescopio Canarias telescope of 13 Galactic H II regions, most of them of very low ionisation degree. The objects are located along the Galactic disc, with RG from 5.7 to 16.1 kpc. We determine Te([N II]) for all of them. We obtain - for the first time - a radial abundance gradient of N that is independent on the ionisation correction factor. The radial distribution of the N/O ratio is almost flat, indicating that the bulk of N is not formed by standard secondary processes. We have made a reassessment of the radial O abundance gradient combining our results with previous similar ones by Esteban et al. (2017); producing a homogeneous dataset of 35 H II regions with direct determinations of the electron temperature. We report the possible presence of a flattening or drop of the O abundance in the inner part of the Galactic disc. This result confirms previous findings from metallicity distributions based on Cepheids and red giants. Finally, we find that the scatter of the N and O abundances of H II regions with respect to the gradient fittings is not substantially larger than the observational uncertainties, indicating that both chemical elements seem to be well mixed in the interstellar gas at a given distance along the Galactic disc

  1. Transition metal complexes with pyrazole-based ligands.Part 29. Reactions of zinc(II and mercury(II thiocyanate with 4-acetyl-3-amino-5-methylpyrazole

    Directory of Open Access Journals (Sweden)

    KATALIN MÉSZÁROS SZÉCSÉNYI

    2009-11-01

    Full Text Available The work is concerned with the crystal and molecular structures of zinc(II and mercury(II complexes with 4-acetyl-3-amino-5-methyl-pyrazole (aamp of the coordination formulae [Zn(NCS2(aamp2] and (Haamp2[Hg(SCN4]. The zinc(II complex was obtained by the reaction of a warm methanolic solution of aamp with a mixture of zinc(II nitrate and ammonium thiocyanate, whereas the mercury(II complex was prepared by the reaction of a warm ethanolic solution of aamp and a warm, slightly acidified aqueous solution of [Hg(SCN4]2-. Both complexes have a tetrahedral geometry, which in the case of zinc complex is formed by monodentate coordination of two aamp molecules and two isothiocyanate groups. The Zn(II and Hg(II atoms have significantly deformed coordination geometry. In both crystal structures the pyrazole derivative has a planar form, probably stabilized by an intramolecular N–H···O hydrogen bond. Apart from the X-ray structural analysis, the isolated complexes were characterized by elemental analysis, IR spectroscopy, conductometric measurements and thermal analysis.

  2. Comparison of analytical techniques for dynamic trace metal speciation in natural freshwaters.

    NARCIS (Netherlands)

    Sigg, Laura; Black, Frank; Buffle, Jacques; Cao, Jun; Cleven, Rob; Davison, William; Galceran, Josep; Gunkel, Peggy; Kalis, Erwin; Kistler, David; Martin, Michel; Noël, Stéphane; Nur, Yusuf; Odzak, Niksa; Puy, Jaume; Riemsdijk, Willem van; Temminghoff, Erwin; Tercier-Waeber, Mary-Lou; Toepperwien, Stefanie; Town, Raewyn M; Unsworth, Emily R; Warnken, Kent W; Weng, Liping; Xue, Hanbin; Zhang, Hao

    2006-01-01

    Several techniques for speciation analysis of Cu, Zn, Cd, Pb, and Ni are used in freshwater systems and compared with respect to their performance and to the metal species detected. The analytical techniques comprise the following: (i) diffusion gradients in thin-film gels (DGT); (ii) gel integrated

  3. The Electronic Structures and Optical Properties of Alkaline-Earth Metals Doped Anatase TiO2: A Comparative Study of Screened Hybrid Functional and Generalized Gradient Approximation.

    Science.gov (United States)

    Ma, Jin-Gang; Zhang, Cai-Rong; Gong, Ji-Jun; Wu, You-Zhi; Kou, Sheng-Zhong; Yang, Hua; Chen, Yu-Hong; Liu, Zi-Jiang; Chen, Hong-Shan

    2015-08-24

    Alkaline-earth metallic dopant can improve the performance of anatase TiO2 in photocatalysis and solar cells. Aiming to understand doping mechanisms, the dopant formation energies, electronic structures, and optical properties for Be, Mg, Ca, Sr, and Ba doped anatase TiO2 are investigated by using density functional theory calculations with the HSE06 and PBE functionals. By combining our results with those of previous studies, the HSE06 functional provides a better description of electronic structures. The calculated formation energies indicate that the substitution of a lattice Ti with an AEM atom is energetically favorable under O-rich growth conditions. The electronic structures suggest that, AEM dopants shift the valence bands (VBs) to higher energy, and the dopant-state energies for the cases of Ca, Sr, and Ba are quite higher than Fermi levels, while the Be and Mg dopants result into the spin polarized gap states near the top of VBs. The components of VBs and dopant-states support that the AEM dopants are active in inter-band transitions with lower energy excitations. As to optical properties, Ca/Sr/Ba are more effective than Be/Mg to enhance absorbance in visible region, but the Be/Mg are superior to Ca/Sr/Ba for the absorbance improvement in near-IR region.

  4. The Electronic Structures and Optical Properties of Alkaline-Earth Metals Doped Anatase TiO2: A Comparative Study of Screened Hybrid Functional and Generalized Gradient Approximation

    Directory of Open Access Journals (Sweden)

    Jin-Gang Ma

    2015-08-01

    Full Text Available Alkaline-earth metallic dopant can improve the performance of anatase TiO2 in photocatalysis and solar cells. Aiming to understand doping mechanisms, the dopant formation energies, electronic structures, and optical properties for Be, Mg, Ca, Sr, and Ba doped anatase TiO2 are investigated by using density functional theory calculations with the HSE06 and PBE functionals. By combining our results with those of previous studies, the HSE06 functional provides a better description of electronic structures. The calculated formation energies indicate that the substitution of a lattice Ti with an AEM atom is energetically favorable under O-rich growth conditions. The electronic structures suggest that, AEM dopants shift the valence bands (VBs to higher energy, and the dopant-state energies for the cases of Ca, Sr, and Ba are quite higher than Fermi levels, while the Be and Mg dopants result into the spin polarized gap states near the top of VBs. The components of VBs and dopant-states support that the AEM dopants are active in inter-band transitions with lower energy excitations. As to optical properties, Ca/Sr/Ba are more effective than Be/Mg to enhance absorbance in visible region, but the Be/Mg are superior to Ca/Sr/Ba for the absorbance improvement in near-IR region.

  5. The removal of toxic metals from liquid effluents by ion exchange resins. Part V: Nickel(II/H+/Dowex C400

    Directory of Open Access Journals (Sweden)

    Francisco José Alguacil

    2017-11-01

    Full Text Available The cationic exchange resin Dowex C400 was used to remove nickel(II from aqueous solutions of different pH values and under various experimental conditions: stirring speed of the aqueous solution/resin system, temperature, resin dosage and aqueous ionic strength. The selectivity of the resin was investigated against the presence of various metals in the aqueous solution, and the removal of nickel(II from aqueous solutions was also compared with results obtained using multiwalled carbon nanotubes or functionalized (carboxylic groups multiwalled carbon nanotubes as adsorbents. According to batch experimental data, best fit of the results is obtained with the Freundlich model, whereas the ion exchange process is best explained by the pseudo-first order model. Experimental data fit well to the moving boundary controlled model. Elution of the nickel(II loaded onto Dowex C400 resin is fully possible using acidic solutions.

  6. Structural basis of Zn(II induced metal detoxification and antibiotic resistance by histidine kinase CzcS in Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Dan Wang

    2017-07-01

    Full Text Available Pseudomonas aeruginosa (P. aeruginosa is a major opportunistic human pathogen, causing serious nosocomial infections among immunocompromised patients by multi-determinant virulence and high antibiotic resistance. The CzcR-CzcS signal transduction system in P. aeruginosa is primarily involved in metal detoxification and antibiotic resistance through co-regulating cross-resistance between Zn(II and carbapenem antibiotics. Although the intracellular regulatory pathway is well-established, the mechanism by which extracellular sensor domain of histidine kinase (HK CzcS responds to Zn(II stimulus to trigger downstream signal transduction remains unclear. Here we determined the crystal structure of the CzcS sensor domain (CzcS SD in complex with Zn(II at 1.7 Å resolution. This is the first three-dimensional structural view of Zn(II-sensor domain of the two-component system (TCS. The CzcS SD is of α/β-fold in nature, and it senses the Zn(II stimulus at micromole level in a tetrahedral geometry through its symmetry-related residues (His55 and Asp60 on the dimer interface. Though the CzcS SD resembles the PhoQ-DcuS-CitA (PDC superfamily member, it interacts with the effector in a novel domain with the N-terminal α-helices rather than the conserved β-sheets pocket. The dimerization of the N-terminal H1 and H1' α-helices is of primary importance for the activity of HK CzcS. This study provides preliminary insight into the molecular mechanism of Zn(II sensing and signaling transduction by the HK CzcS, which will be beneficial to understand how the pathogen P. aeruginosa resists to high levels of heavy metals and antimicrobial agents.

  7. Non-bonding interactions and non-covalent delocalization effects play a critical role in the relative stability of group 12 complexes arising from interaction of diethanoldithiocarbamate with the cations of transition metals Zn(II), Cd(II), and Hg(II): a theoretical study.

    Science.gov (United States)

    Bahrami, Homayoon; Farhadi, Saeed; Siadatnasab, Firouzeh

    2016-07-01

    The chelating properties of diethanoldithiocarbamate (DEDC) and π-electron flow from the nitrogen atom to the sulfur atom via a plane-delocalized π-orbital system (quasi ring) was studied using a density functional theory method. The molecular structure of DEDC and its complexes with Zn(II), Cd(II), and Hg(II) were also considered. First, the geometries of this ligand and DEDC-Zn(II), DEDC-Cd(II), and DEDC-Hg(II) were optimized, and the formation energies of these complexes were then calculated based on the electronic energy, or sum of electronic energies, with the zero point energy of each species. Formation energies indicated the DEDC-Zn(II) complex as the most stable complex, and DEDC-Cd(II) as the least stable. Structural data showed that the N1-C2 π-bond was localized in the complexes rather than the ligand, and a delocalized π-bond over S7-C2-S8 was also present. The stability of DEDC-Zn(II), DEDC-Cd(II), and DEDC-Hg(II) complexes increased in the presence of the non-specific effects of the solvent (PCM model), and their relative stability did not change. There was π-electron flow or resonance along N1-C2-S7 and along S7-C2-S8 in the ligand. The π-electron flow or resonance along N1-C2-S7 was abolished when the metal interacted with sulfur atoms. Energy belonging to van der Waals interactions and non-covalent delocalization effects between the metal and sulfur atoms of the ligand was calculated for each complex. The results of nucleus-independent chemical shift (NICS) indicated a decreasing trend as Zn(II) Hg(II) for the aromaticity of the quasi-rings. Finally, by ignoring van der Waals interactions and non-covalent delocalization effects between the metal and sulfur atoms of the ligand, the relative stability of the complexes was changed as follows:[Formula: see text] Graphical Abstract Huge electronic cloud localized on Hg(II) in the Hg(II)-DEDC complex.

  8. Interactions of nickel(II) with histones: enhancement of 2'-deoxyguanosine oxidation by Ni(II) complexes with CH3CO-Cys-Ala-Ile-His-NH2, a putative metal binding sequence of histone H3.

    Science.gov (United States)

    Bal, W; Lukszo, J; Kasprazak, K S

    1996-03-01

    Studies of 2'-deoxyguanosine oxidation by hydrogen peroxide in the presence of CH3CO-Cys-Ala-Ile-His-NH2 (CAIH) and/or NiCl2 have been carried out in 100 mM phosphate buffer (pH 7.4) at 37 degrees C. The dimeric CAIH oxidation product, CAIH disulfide, and its weak, octahedral Ni(II) complex, rather than the monomeric CAIH and its strong, square-planar Ni(II) complex, were found to be major catalysts of 8-oxo-2'-deoxyguanosine (8-oxo-dG) formation. The presence of Ni(II) largely enhanced 8-oxo-dG yield, especially at submillimolar concentrations of H2O2. The reaction was found not to involve detectable amounts of free radicals or Ni(III). These results, together with those published previously [Bal, W. et al. (1995) Chem. Res. Toxicol. 8, 683-692], lay a framework for the detailed investigations of the interactions of histone octamer with Ni(II) and other metal ions. They also suggest that molecular mechanisms of nickel carcinogenesis may involve oxidative damage processes catalyzed by weak Ni(II) complexes with cellular components.

  9. Enhanced phytoextraction: II. Effect of EDTA and citric acid on heavy metal uptake by Helianthus annuus from a calcareous soil.

    Science.gov (United States)

    Lesage, E; Meers, E; Vervaeke, P; Lamsal, S; Hopgood, M; Tack, F M G; Verloo, M G

    2005-01-01

    High biomass producing plant species, such as Helianthus annuus, have potential for removing large amounts of trace metals by harvesting the aboveground biomass if sufficient metal concentrations in their biomass can be achieved However, the low bioavailability of heavy metals in soils and the limited translocation of heavy metals to the shoots by most high biomass producing plant species limit the efficiency of the phytoextraction process. Amendment of a contaminated soil with ethylene diamine tetraacetic acid (EDTA) or citric acid increases soluble heavy metal concentrations, potentially rendering them more available for plant uptake. This article discusses the effects of EDTA and citric acid on the uptake of heavy metals and translocation to aboveground harvestable plant parts in Helianthus annuus. EDTA was included in the research for comparison purposes in our quest for less persistent alternatives, suitable for enhanced phytoextraction. Plants were grown in a calcareous soil moderately contaminated with Cu, Pb, Zn, and Cd and treated with increasing concentrations of EDTA (0.1, 1, 3, 5, 7, and 10 mmol kg(-1) soil) or citric acid (0.01, 0.05, 0.25, 0.442, and 0.5 mol kg(-1) soil). Heavy metal concentrations in harvested shoots increased with EDTA concentration but the actual amount of phytoextracted heavy metals decreased at high EDTA concentrations, due to severe growth depression. Helianthus annuus suffered heavy metal stress due to the significantly increased bioavailable metal fraction in the soil. The rapid mineralization of citric acid and the high buffering capacity of the soil made citric acid inefficient in increasing the phytoextracted amounts of heavy metals. Treatments that did not exceed the buffering capacity of the soil (heavy metal concentrations. Treatments with high concentrations resulted in a dissolution of the carbonates and compaction of the soil. These physicochemical changes caused growth depression of Helianthus annuus. EDTA and citric

  10. Precious metals in SDSS quasar spectra. II. Tracking the evolution of strong, 0.4 < z < 2.3 Mg II absorbers with thousands of systems

    International Nuclear Information System (INIS)

    Seyffert, Eduardo N.; Simcoe, Robert A.; Cooksey, Kathy L.; O'Meara, John M.; Kao, Melodie M.; Prochaska, J. Xavier

    2013-01-01

    We have performed an analysis of over 34,000 Mg II doublets at 0.36 < z < 2.29 in Sloan Digital Sky Survey (SDSS) Data Release 7 quasar spectra; the catalog, advanced data products, and tools for analysis are publicly available. The catalog was divided into 14 small redshift bins with roughly 2500 doublets in each and from Monte Carlo simulations, we estimate 50% completeness at rest equivalent width W r ≈ 0.8 Å. The equivalent width frequency distribution is described well by an exponential model at all redshifts, and the distribution becomes flatter with increasing redshift, i.e., there are more strong systems relative to weak ones. Direct comparison with previous SDSS Mg II surveys reveals that we recover at least 70% of the doublets in these other catalogs, in addition to detecting thousands of new systems. We discuss how these surveys came by their different results, which qualitatively agree but because of the very small uncertainties, differ by a statistically significant amount. The estimated physical cross section of Mg II-absorbing galaxy halos increased approximately threefold from z = 0.4 to z = 2.3, while the W r ≥ 1 Å absorber line density, dN MgII /dX, grew by roughly 45%. Finally, we explore the different evolution of various absorber populations—damped Lyα absorbers, Lyman limit systems, strong C IV absorbers, and strong and weaker Mg II systems—across cosmic time (0 < z < 6).

  11. Synthesis, Characterization and Antibacterial Activity of Novel 1,3-Diethyl-1,3-bis(4-nitrophenylurea and Its Metal(II Complexes

    Directory of Open Access Journals (Sweden)

    Hoda Pasdar

    2017-12-01

    Full Text Available A bioactive ligand and its dinuclear metal(II complexes were synthesized and characterized by Fourier-transform infrared spectroscopy (FT-IR, ultraviolet-visible (UV-Visible, nuclear magnetic resonance (1H-NMR, mass spectroscopy and molar conductance measurements. The ligand has been crystalized in the monoclinic system with a P21/c space group. The biological activities of metal complexes were evaluated using disc diffusion and broth dilution methods. In vitro antibacterial activities of the ligand and their metal complexes were examined against two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus and two Gram-negative bacteria (Escherichia coli and Serratia marcescens and compared to the standard drugs. It was found that metal complexes displayed much higher antibacterial activities and better inhibitory effects than that of the ligand and standard drugs. Among these complexes, the compound having Zn-metal showed greater antibacterial activity against all four tested bacteria and was more effective against Serratia marcescens with the zone inhibition diameter of 26 mm and MIC value of 31.25 µg/mL.

  12. Pyrolysis as a technique for separating heavy metals from hyperaccumulators. Part II: Lab-scale pyrolysis of synthetic hyperaccumulator biomass

    International Nuclear Information System (INIS)

    Koppolu, Lakshmi; Agblevor, F.A.; Clements, L.D.

    2003-01-01

    Synthetic hyperaccumulator biomass (SHB) impregnated with Ni, Zn, Cu, Co or Cr was used to conduct 11 experiments in a lab-scale fluidized bed reactor. Two runs with blank corn stover, with no metal added, were also conducted. The reactor was operated in an entrained mode in a oxygen-free (N 2 ) environment at 873 K and 1 atm. The apparent gas residence time through the lab-scale reactor was 0.6 s at 873 K. The material balance for the lab-scale experiments on N 2 -free basis varied between 81% and 98%. The presence of a heavy metal in the SHB decreased the char yield and increased the tar yield, compared to the blank. The char and gas yields appeared to depend on the form of the metal salt used to prepare the SHB. However, the metal distribution in the product streams did not seem to be influenced by the chemical form of the metal salt used to prepare the SHB. Greater than 98.5% of the metal in the product stream was concentrated in the char formed by pyrolyzing and gasifying the SHB in the reactor. The metal concentration in the char varied between 0.7 and 15.3% depending on the type of metal in the SHB. However, the metal concentration was increased 4 to 6 times in the char compared to the feed

  13. Clinical assessment of class II resin-based composites versus preformed metal crowns performed on primary molars in patients at high risk of caries.

    Science.gov (United States)

    Alyahya, A; Khanum, A; Qudeimat, M

    2018-02-01

    To compare class II resin composite with preformed metal crowns (PMC) in the treatment of proximal dentinal caries in high caries-risk patients. The charts (270) of paediatric patients with proximal caries of their primary molars were reviewed. Success or failure of a procedure was assessed using the dental notes. Survival analysis was used to calculate the mean survival time (MST) for both procedures. The influence of variables on the mean survival time was investigated. A total of 593 class II resin composites and 243 PMCs were placed in patients ranging between 4-13 years of age. The failure percentage of class II resin composites was 22.6% with the majority having been due to recurrent caries, while the failure percentage of PMCs was 15.2% with the majority due to loss of the crown. There was no significant difference between the MST of class II resin composites and PMCs, 41.3 and 45.6 months respectively (p value = 0.06). In class II resin composites, mesial restorations were associated with lower MST compared to distal restorations (p-value composites and PMCs were comparable when performed on high caries-risk patients.

  14. Guest Induced Strong Cooperative One- and Two-Step Spin Transitions in Highly Porous Iron(II) Hofmann-Type Metal-Organic Frameworks.

    Science.gov (United States)

    Piñeiro-López, Lucı A; Valverde-Muñoz, Francisco Javier; Seredyuk, Maksym; Muñoz, M Carmen; Haukka, Matti; Real, José Antonio

    2017-06-19

    The synthesis, crystal structure, magnetic, calorimetric, and Mössbauer studies of a series of new Hofmann-type spin crossover (SCO) metal-organic frameworks (MOFs) is reported. The new SCO-MOFs arise from self-assembly of Fe II , bis(4-pyridyl)butadiyne (bpb), and [Ag(CN) 2 ] - or [M II (CN) 4 ] 2- (M II = Ni, Pd). Interpenetration of four identical 3D networks with α-Po topology are obtained for {Fe(bpb)[Ag I (CN) 2 ] 2 } due to the length of the rod-like bismonodentate bpb and [Ag(CN) 2 ] - ligands. The four networks are tightly packed and organized in two subsets orthogonally interpenetrated, while the networks in each subset display parallel interpenetration. This nonporous material undergoes a very incomplete SCO, which is rationalized from its intricate structure. In contrast, the single network Hofmann-type MOFs {Fe(bpb)[M II (CN) 4 ]}·nGuest (M II = Ni, Pd) feature enhanced porosity and display complete one-step or two-step cooperative SCO behaviors when the pores are filled with two molecules of nitrobenzene or naphthalene that interact strongly with the pyridyl and cyano moieties of the bpb ligands via π-π stacking. The lack of these guest molecules favors stabilization of the high-spin state in the whole range of temperatures. However, application of hydrostatic pressure induces one- and two-step SCO.

  15. Bioassay studies of metal(II complexes of 2,2'-(ethane-1,2-diyldiiminodiacetic acid

    Directory of Open Access Journals (Sweden)

    Saeed-ur-Rehman

    2011-08-01

    Full Text Available Ni(II, Cu(II and Zn(II coordination compounds with modified diammine 2,2'-(ethane-1,2-diyldiiminodiacetic acid (EDDA were prepared and characterized. Coordination complexes of the EDDA were characterized by physical measurements including elemental analysis, IR, UV-Visible, magnetic susceptibilities and conductance measurements. The complexes were screened against four pathogenic bacteria like Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus and their concentrations for maximum inhibition zones were obtained.

  16. Gradients of stellar population properties and evolution clues in a nearby galaxy M101

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Lin; Kong, Xu; Lin, Xuanbin; Mao, Yewei; Cheng, Fuzhen [Center for Astrophysics, University of Science and Technology of China, Hefei 230026 (China); Zou, Hu; Jiang, Zhaoji; Zhou, Xu, E-mail: linlin@mail.ustc.edu.cn, E-mail: xkong@ustc.edu.cn, E-mail: zouhu@nao.cas.cn [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2013-06-01

    Multiband photometric images from ultraviolet and optical to infrared are collected to derive spatially resolved properties of the nearby Scd-type galaxy M101. With evolutionary stellar population synthesis models, two-dimensional distributions and radial profiles of age, metallicity, dust attenuation, and star formation timescale in the form of the Sandage star formation history are obtained. When fitting with the models, we use the IRX-A {sub FUV} relation, found to depend on a second parameter of birth rate b (ratio of present- and past-averaged star formation rates), to constrain the dust attenuation. There are obvious parameter gradients in the disk of M101, which supports the theory of an 'inside-out' disk growth scenario. Two distinct disk regions with different gradients of age and color are discovered, similar to another late-type galaxy, NGC 628. The metallicity gradient of the stellar content is flatter than that of H II regions. The stellar disk is optically thicker inside than outside and the global dust attenuation of this galaxy is lower compared with galaxies of similar and earlier morphological type. We note that a variational star formation timescale describes the real star formation history of a galaxy. The timescale increases steadily from the center to the outskirt. We also confirm that the bulge in this galaxy is a disk-like pseudobulge, whose evolution is likely to be induced by some secular processes of the small bar which is relatively young, metal-rich, and contains much dust.

  17. [PHEMA/PEI]–Cu(II) based immobilized metal affinity chromatography cryogels: Application on the separation of IgG from human plasma

    Energy Technology Data Exchange (ETDEWEB)

    Bakhshpour, Monireh; Derazshamshir, Ali; Bereli, Nilay [Department of Chemistry, Biochemistry Division, Hacettepe University, Ankara (Turkey); Elkak, Assem [Laboratory of “Valorisation des Ressources Naturelles et Produits de Santé (VRNPS)”, Doctoral School of Sciences and Technology, Lebanese University, Rafic Hariri University Campus, Hadath (Lebanon); Denizli, Adil, E-mail: denizli@hacettepe.edu [Department of Chemistry, Biochemistry Division, Hacettepe University, Ankara (Turkey)

    2016-04-01

    The immobilized metal-affinity chromatography (IMAC) has gained significant interest as a widespread separation and purification tool for therapeutic proteins, nucleic acids and other biological molecules. The enormous potential of IMAC for proteins with natural surface exposed-histidine residues and for recombinant proteins with histidine clusters. Cryogels as monolithic materials have recently been proposed as promising chromatographic adsorbents for the separation of biomolecules in downstream processing. In the present study, IMAC cryogels have been synthesized and utilized for the adsorption and separation of immunoglobulin G (IgG) from IgG solution and whole human plasma. For this purpose, Cu(II)-ions were coupled to poly(hydroxyethyl methacrylate) PHEMA using poly(ethylene imine) (PEI) as the chelating ligand. In this study the cryogels formation optimized by the varied proportion of PEI from 1% to 15% along with different amounts of Cu (II) as chelating metal. The prepared cryogels were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The [PHEMA/PEI]–Cu(II) cryogels were assayed for their capability to bind the human IgG from aqueous solutions. The IMAC cryogels were found to have high affinity toward human IgG. The adsorption of human IgG was investigated onto the PHEMA/PEI cryogels with (10% PEI) and the concentration of Cu (II) varied as 10, 50, 100 and 150 mg/L. The separation of human IgG was achieved in one purification step at pH 7.4. The maximum adsorption capacity was observed at the [PHEMA/PEI]–Cu(II) (10% PEI) with 72.28 mg/g of human IgG. The purification efficiency and human IgG purity were investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). - Highlights: • Cu(II)-ions were coupled to PHEMA using PEI as the chelating ligand. • Cu(II) chelated [PHEMA/PEI] cryogels for IgG separation were produced. • Maximum IgG adsorption capacity

  18. [PHEMA/PEI]–Cu(II) based immobilized metal affinity chromatography cryogels: Application on the separation of IgG from human plasma

    International Nuclear Information System (INIS)

    Bakhshpour, Monireh; Derazshamshir, Ali; Bereli, Nilay; Elkak, Assem; Denizli, Adil

    2016-01-01

    The immobilized metal-affinity chromatography (IMAC) has gained significant interest as a widespread separation and purification tool for therapeutic proteins, nucleic acids and other biological molecules. The enormous potential of IMAC for proteins with natural surface exposed-histidine residues and for recombinant proteins with histidine clusters. Cryogels as monolithic materials have recently been proposed as promising chromatographic adsorbents for the separation of biomolecules in downstream processing. In the present study, IMAC cryogels have been synthesized and utilized for the adsorption and separation of immunoglobulin G (IgG) from IgG solution and whole human plasma. For this purpose, Cu(II)-ions were coupled to poly(hydroxyethyl methacrylate) PHEMA using poly(ethylene imine) (PEI) as the chelating ligand. In this study the cryogels formation optimized by the varied proportion of PEI from 1% to 15% along with different amounts of Cu (II) as chelating metal. The prepared cryogels were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The [PHEMA/PEI]–Cu(II) cryogels were assayed for their capability to bind the human IgG from aqueous solutions. The IMAC cryogels were found to have high affinity toward human IgG. The adsorption of human IgG was investigated onto the PHEMA/PEI cryogels with (10% PEI) and the concentration of Cu (II) varied as 10, 50, 100 and 150 mg/L. The separation of human IgG was achieved in one purification step at pH 7.4. The maximum adsorption capacity was observed at the [PHEMA/PEI]–Cu(II) (10% PEI) with 72.28 mg/g of human IgG. The purification efficiency and human IgG purity were investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). - Highlights: • Cu(II)-ions were coupled to PHEMA using PEI as the chelating ligand. • Cu(II) chelated [PHEMA/PEI] cryogels for IgG separation were produced. • Maximum IgG adsorption capacity

  19. The removal of toxic metals from liquid effluents by ion exchange resins. Part VI: Manganese(II/H+/Lewatit K2621

    Directory of Open Access Journals (Sweden)

    Francisco J. Alguacil

    2018-05-01

    Full Text Available In this sixth part of the series, Manganese(II was removed from aqueous solutions by the cationic exchange resin Lewatit K2621. The investigation was performed under various experimental conditions such as the stirring speed associated with the system, aqueous pH, temperature, resin dosage and the ionic strength of the solution. The performance of the resin against the loading of metals from metal-binary solutions as well as the removal of Manganese(II from the solutions using multiwalled carbon nanotubes and functionalized (carboxylic groups multiwalled carbon nanotubes, were also investigated. Experimental results fit well with the pseudo-first kinetic order model, whereas fit of the data show that at 20 °C the process responded well to the diffusion controlled model, and that at 60 °C, the system is controlled by the moving boundary model. Adsorption data is better related to the Freundlich isotherm. Elution of the Manganese(II loaded onto the resin was investigated using acidic (H2SO4 or HCl solutions.

  20. Content and uptake of trace metals in benthic algae, Enteromorpha and Porphyra. II. Studies on the algae cultured in sea water supplemented with various metals

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, M.; Fujiyama, T.

    1977-01-01

    In the culture of Porphyra in sea water supplemented with metals, the uptakes of Mn and Cd were relatively high and increased in proportion to culture time when the metal concentration in water was high. Fe distributed evenly in all three parts of fronds. Mn was concentrated in surface and middle layers, while Cd was accumulated mainly in the middle layer and a little in the surface layer. In general the uptake was high in the middle layer. In the uptake of Mn there was a clear distinction between light and dark conditions, that is, Mn was absorbed only during light periods while Cd was absorbed regardless of light and dark periods.

  1. Theoretical investigation, biological evaluation and VEGFR2 kinase studies of metal(II) complexes derived from hydrotris(methimazolyl)borate.

    Science.gov (United States)

    Jayakumar, S; Mahendiran, D; Srinivasan, T; Mohanraj, G; Kalilur Rahiman, A

    2016-02-01

    The reaction of soft tripodal scorpionate ligand, sodium hydrotris(methimazolyl)borate with M(ClO4)2·6H2O [MMn(II), Ni(II), Cu(II) or Zn(II)] in methanol leads to the cleavage of B-N bond followed by the formation of complexes of the type [M(MeimzH)4](ClO4)2·H2O (1-4), where MeimzH=methimazole. All the complexes were fully characterized by spectro-analytical techniques. The molecular structure of the zinc(II) complex (4) was determined by X-ray crystallography, which supports the observed deboronation reaction in the scorpionate ligand with tetrahedral geometry around zinc(II) ion. The electronic spectra of complexes suggested tetrahedral geometry for manganese(II) and nickel(II) complexes, and square-planar geometry for copper(II) complex. Frontier molecular orbital analysis (HOMO-LUMO) was carried out by B3LYP/6-31G(d) to understand the charge transfer occurring in the molecules. All the complexes exhibit significant antimicrobial activity against Gram (-ve) and Gram (+ve) bacterial as well as fungal strains, which are quite comparable to standard drugs streptomycin and clotrimazole. The copper(II) complex (3) showed excellent free radical scavenging activity against DPPH in all concentration with IC50 value of 30μg/mL, when compared to the other complexes. In the molecular docking studies, all the complexes showed hydrophobic, π-π and hydrogen bonding interactions with BSA. The cytotoxic activity of the complexes against human hepatocellular liver carcinoma (HepG2) cells was assessed by MTT assay, which showed exponential responses toward increasing concentration of complexes. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. SEARCH FOR BLUE COMPACT DWARF GALAXIES DURING QUIESCENCE. II. METALLICITIES OF GAS AND STARS, AGES, AND STAR FORMATION RATES

    International Nuclear Information System (INIS)

    Sanchez Almeida, J.; Aguerri, J. A. L.; Munoz-Tunon, C.; Vazdekis, A.

    2009-01-01

    We examine the metallicity and age of a large set of Sloan Digital Sky Survey/Data Release 6 galaxies that may be blue compact dwarf (BCD) galaxies during quiescence (QBCDs). The individual spectra are first classified and then averaged to reduce noise. The metallicity inferred from emission lines (tracing ionized gas) exceeds by ∼0.35 dex the metallicity inferred from absorption lines (tracing stars). Such a small difference is significant according to our error budget estimate. The same procedure was applied to a reference sample of BCDs, and in this case the two metallicities agree, being also consistent with the stellar metallicity in QBCDs. Chemical evolution models indicate that the gas metallicity of QBCDs is too high to be representative of the galaxy as a whole, but it can represent a small fraction of the galactic gas, self-enriched by previous starbursts. The luminosity-weighted stellar age of QBCDs spans the whole range between 1 and 10 Gyr, whereas it is always smaller than 1 Gyr for BCDs. Our stellar ages and metallicities rely on a single stellar population spectrum fitting procedure, which we have specifically developed for this work using the stellar library MILES.

  3. Structural and compositional gradients: basic idea, preparation, applications

    International Nuclear Information System (INIS)

    Ilschner, B.

    1993-01-01

    The term gradient materials refers to gradients of chemical composition and/or microstructural parameters which are intentionally introduced into components of any kind of homogeneous or heterogeneous materials, including metallic alloys, ceramics, glasses, polymers, and composites. After a short review of the development of the gradient materials technology since 1972, some fundamental aspects concerning the effects of such gradients on physical or mechanical properties are discussed. A selection of technical applications which have been discussed recently is presented. Finally, different methods for the preparation of gradients from gaseous, liquid or powder precursors are reviewed. (orig.)

  4. Synthesis, characterization, DNA-binding study and anticancer properties of ternary metal(II) complexes of edda and an intercalating ligand.

    Science.gov (United States)

    Ng, Chew Hee; Kong, King Chow; Von, Sze Tin; Balraj, Pauline; Jensen, Paul; Thirthagiri, Eswary; Hamada, Hirokazu; Chikira, Makoto

    2008-01-28

    A series of ternary metal(ii) complexes {M(phen)(edda); 1a (Cu), 1b (Co), 1c (Zn), 1d (Ni); H(2)edda = N,N(')-ethylenediaminediacetic acid} of N,N'-ethylene-bridged diglycine and 1,10-phenanthroline were synthesized and characterized by elemental analysis, FTIR, UV-visible spectroscopy and magnetic susceptibility measurement. The interaction of these complexes with DNA was investigated using CD and EPR spectroscopy. MTT assay results of 1a-1c , screened on MCF-7 cancer cell lines, show that synergy between the metal and ligands results in significant enhancement of their antiproliferative properties. Preliminary results from apoptosis and cell cycle analyses with flow cytometry are reported. seems to be able to induce cell cycle arrest at G(0)/G(1). The crystal structure of 1a is also included.

  5. Anchoring of Cu(II) onto surface of porous metal-organic framework through post-synthesis modification for the synthesis of benzimidazoles and benzothiazoles

    Science.gov (United States)

    Kardanpour, Reihaneh; Tangestaninejad, Shahram; Mirkhani, Valiollah; Moghadam, Majid; Mohammadpoor-Baltork, Iraj; Zadehahmadi, Farnaz

    2016-03-01

    Efficient synthesis of various benzimidazoles and benzothiazoles under mild conditions catalyzed by Cu(II) anchored onto UiO-66-NH2 metal organic framework is reported. In this manner, first, the aminated UiO-66 was modified with thiophene-2-carbaldehyde and then the prepared Schiff base was reacted with CuCl2. The prepared catalyst was characterized by FT-IR, UV-vis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption, inductively coupled plasma atomic emission spectroscopy (ICP-AES) and field emission scanning electron microscopy (FE-SEM). The UiO-66-NH2-TC-Cu was applied as a highly efficient catalyst for synthesis of benzimidazole and benzothiazole derivatives by the reaction of aldehydes with 1,2-diaminobenzene or 2-aminothiophenol. The Cu(II)-containing MOF was reused several times without any appreciable loss of its efficiency.

  6. Detection of Copper (II) and Cadmium (II) binding to dissolved organic matter from macrophyte decomposition by fluorescence excitation-emission matrix spectra combined with parallel factor analysis

    International Nuclear Information System (INIS)

    Yuan, Dong-hai; Guo, Xu-jing; Wen, Li; He, Lian-sheng; Wang, Jing-gang; Li, Jun-qi

    2015-01-01

    Fluorescence excitation-emission matrix (EEM) spectra coupled with parallel factor analysis (PARAFAC) was used to characterize dissolved organic matter (DOM) derived from macrophyte decomposition, and to study its complexation with Cu (II) and Cd (II). Both the protein-like and the humic-like components showed a marked quenching effect by Cu (II). Negligible quenching effects were found for Cd (II) by components 1, 5 and 6. The stability constants and the fraction of the binding fluorophores for humic-like components and Cu (II) can be influenced by macrophyte decomposition of various weight gradients in aquatic plants. Macrophyte decomposition within the scope of the appropriate aquatic phytomass can maximize the stability constant of DOM-metal complexes. A large amount of organic matter was introduced into the aquatic environment by macrophyte decomposition, suggesting that the potential risk of DOM as a carrier of heavy metal contamination in macrophytic lakes should not be ignored. - Highlights: • Macrophyte decomposition increases fluorescent DOM components in the upper sediment. • Protein-like components are quenched or enhanced by adding Cu (II) and Cd (II). • Macrophyte decomposition DOM can impact the affinity of Cu (II) and Cd (II). • The log K M and f values showed a marked change due to macrophyte decomposition. • Macrophyte decomposition can maximize the stability constant of DOM-Cu (II) complexes. - Macrophyte decomposition DOM can influence on the binding affinity of metal ions in macrophytic lakes

  7. Influence of divalent metal on the decomposition products of hydrotalcite-like ternary systems M{sup II}-Al-Cr (M{sup II} = Zn, Cd)

    Energy Technology Data Exchange (ETDEWEB)

    Perez, M.R.; Crespo, I.; Ulibarri, M.A.; Barriga, C. [Departamento de Quimica Inorganica e Ingenieria Quimica, Campus de Rabanales, Universidad de Cordoba, Cordoba (Spain); Rives, V. [GIR-QUESCAT, Departamento de Quimica Inorganica, Universidad de Salamanca, Salamanca (Spain); Fernandez, J.M., E-mail: um1feroj@uco.es [Departamento de Quimica Inorganica e Ingenieria Quimica, Campus de Rabanales, Universidad de Cordoba, Cordoba (Spain)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer LDHs M{sup II}-Al-Cr (M = Zn, Cd) with Cr in the layer or interlayer have been prepared. Black-Right-Pointing-Pointer LDHs Zn-Al or Zn-Cr decompose by heating forming ZnO and ZnAl{sub 2}O{sub 4} or ZnO and ZnCr{sub 2}O{sub 4}. Black-Right-Pointing-Pointer LDHs Zn-Al-Cr give rise to the formation of ZnO and the mixed spinel ZnAl{sub 2-x}Cr{sub x}O{sub 4}. Black-Right-Pointing-Pointer LDH Cd-Al-Cr shows the formation of CdO, CdCr{sub 2-x}Al{sub x}O{sub 4}, and (Al, Cr){sub 2}O{sub 3} mixed oxide. Black-Right-Pointing-Pointer Calcination of the CdAl-CrO{sub 4} give rise to (Al, Cr){sub 2}O{sub 3} as the majority phase. - Abstract: Layered double hydroxides (LDHs) containing M{sup II}, Al{sup III}, and Cr{sup III} in the brucite-like layers (M = Cd, Zn) with different starting Al/Cr molar ratios and nitrate/carbonate as the interlayer anion have been prepared following the coprecipitation method at a constant pH: Zn{sup II}-Al{sup III}-Cr{sup III}-CO{sub 3}{sup 2-} at pH = 10, and Cd{sup II}-Al{sup III}-Cr{sup III}-NO{sub 3}{sup -} at pH = 8. Two additional M{sup II},Al{sup III}-LDH samples (M = Cd, Zn) with chromate ions (CrO{sub 4}{sup 2-}) in the interlayer have been prepared by ionic exchange at pH = 9 and 8, respectively, starting from M{sup II}-Al{sup III}-NO{sub 3}{sup -}. The samples have been characterised by absorption atomic spectrometry, powder X-ray diffraction (PXRD), FT-IR spectroscopy and transmission electron microscopy (TEM). Their thermal stability has been assessed by DTA-TG and mass spectrometric analysis of the evolved gases. The PXRD patterns of the solids calcined at 800 Degree-Sign C show diffraction lines corresponding to ZnO and ZnAl{sub 2-x}Cr{sub x}O{sub 4} for the Zn-containing samples, and diffraction lines attributed to CdO and CdCr{sub 2}O{sub 4} and (Al,Cr){sub 2}O{sub 3} for the Cd-containing ones. Additionally a minority oxide, Cd{sub 2}CrO{sub 5}, is observed to Cd{sup II}-Al{sup III

  8. Genetic toxicology of metal compounds. II. Enhancement of ultraviolet light-induced mutagenesis in Escherichia coli WP2

    International Nuclear Information System (INIS)

    Rossman, T.G.; Molina, M.

    1986-01-01

    Salts of metals which are carcinogenic, noncarcinogenic, or of unknown carcinogenicity were assayed for their abilities to modulate ultraviolet (UV)-induced mutagenesis in Escherichia coli WP2. In addition to the previously reported comutagenic effect of arsenite, salts of three other compounds were found to enhance UV mutagenesis. CuCl 2 , MnCl 2 (and a small effect by KMnO 4 ), and NaMoO 4 acted as comutagens in E coli WP2, which has wild-type DNA repair capability, but were much less comutagenic in the repair deficient strain WP2/sub s/ (uvrA). The survival of irradiated or unirradiated cells was not affected by these compounds. No effects on UV mutagenesis were seen for 16 other metal compounds. We suggest that the comutagenic effects might occur either via metal-induced decreases in the fidelity of repair replication or via metal-induced depurination

  9. Formation of Mixed-Ligand Complexes of Metals(II) with Monoamine Complexones and Amino Acids in Solution

    Science.gov (United States)

    Pyreu, D. F.; Gridchin, S. N.

    2018-05-01

    The formation of mixed-ligand complexes in the M(II)-Nta, Ida-L (M = Cu(II), Ni, Zn, Co(II), L = Ser, Thr, Asp, Arg, Asn) systems, where Ida and Nta are the residues of iminodiacetic and nitrilotriacetic acids, respectively, is studied using pH measurements, calorimetry and spectrophotometry. The thermodynamic parameters (log K, Δr G 0, Δr H, Δr S) of their formation at 298.15 K and ionic strength I = 0.5 (KNO3) are determined. The most likely scenario of amino acid residue coordination in the composition of mixed complexes is discussed.

  10. Particle capture efficiency in a multi-wire model for high gradient magnetic separation

    KAUST Repository

    Eisenträ ger, Almut; Vella, Dominic; Griffiths, Ian M.

    2014-01-01

    High gradient magnetic separation (HGMS) is an efficient way to remove magnetic and paramagnetic particles, such as heavy metals, from waste water. As the suspension flows through a magnetized filter mesh, high magnetic gradients around the wires

  11. A KECK HIRES DOPPLER SEARCH FOR PLANETS ORBITING METAL-POOR DWARFS. II. ON THE FREQUENCY OF GIANT PLANETS IN THE METAL-POOR REGIME

    International Nuclear Information System (INIS)

    Sozzetti, Alessandro; Torres, Guillermo; Latham, David W.; Stefanik, Robert P.; Korzennik, Sylvain G.; Boss, Alan P.; Carney, Bruce W.; Laird, John B.

    2009-01-01

    We present an analysis of three years of precision radial velocity (RV) measurements of 160 metal-poor stars observed with HIRES on the Keck 1 telescope. We report on variability and long-term velocity trends for each star in our sample. We identify several long-term, low-amplitude RV variables worthy of followup with direct imaging techniques. We place lower limits on the detectable companion mass as a function of orbital period. Our survey would have detected, with a 99.5% confidence level, over 95% of all companions on low-eccentricity orbits with velocity semiamplitude K ∼> 100 m s -1 , or M p sin i ∼> 3.0 M J (P/yr) (1/3) , for orbital periods P ∼ p p ≅ 1%. Our results can usefully inform theoretical studies of the process of giant-planet formation across two orders of magnitude in metallicity.

  12. Transport of trace metals in the Magela Creek system, Northern Territory. II. Trace metal concentrations in the Magela Creek billabongs at the end of the 1978 dry season

    International Nuclear Information System (INIS)

    Davies, S.H.R.; Hart, B.T.

    1981-12-01

    Billabongs downstream of the Ranger uranium mining operation have been identified as potential deposition areas for released trace metals. Samples were taken at the end of the dry season and analysed for total and filterable concentrations of Fe, Mn, Cd, Cu and Zn. There was an increase in the concentrations of total Fe, Zn, Cd and Cu in the backflow and flood plain billabongs compared with the concentrations recorded during the wet season. The increase was most noticeable for iron

  13. Coordination of different ligands to copper(II) and cobalt(III) metal centers enhances Zika virus and dengue virus loads in both arthropod cells and human keratinocytes.

    Science.gov (United States)

    Dutta, Shovan; Celestine, Michael J; Khanal, Supreet; Huddleston, Alexis; Simms, Colin; Arca, Jessa Faye; Mitra, Amlan; Heller, Loree; Kraj, Piotr J; Ledizet, Michel; Anderson, John F; Neelakanta, Girish; Holder, Alvin A; Sultana, Hameeda

    2018-01-01

    Trace elements such as copper and cobalt have been associated with virus-host interactions. However, studies to show the effect of conjugation of copper(II) or cobalt(III) metal centers to thiosemicarbazone ligand(s) derived from either food additives or mosquito repellent such as 2-acetylethiazole or citral, respectively, on Zika virus (ZIKV) or dengue virus (serotype 2; DENV2) infections have not been explored. In this study, we show that four compounds comprising of thiosemicarbazone ligand derived from 2-acetylethiazole viz., (E)-N-ethyl-2-[1-(thiazol-2-yl)ethylidene]hydrazinecarbothioamide (acetylethTSC) (compound 1), a copper(II) complex with acetylethTSC as a ligand (compound 2), a thiosemicarbazone ligand-derived from citral (compound 3) and a cobalt(III) complex with a citral-thiosemicarbazone ligand (compound 4) increased DENV2 and ZIKV replication in both mosquito C6/36 cells and human keratinocytes (HaCaT cells). Treatment of both cell lines with compounds 2 or 4 showed increased dengue viral titers at all three tested doses. Enhanced dengue viral plaque formation was also noted at the tested dose of 100μM, suggesting higher production of infectious viral particles. Treatment with the compounds 2 or 4 enhanced ZIKV and DENV2 RNA levels in HeLa cell line and primary cultures of mouse bone marrow derived dendritic cells. Also, pre- or post treatments with conjugated compounds 2 or 4 showed higher loads of ZIKV or DENV2 envelope (E) protein in HaCaT cells. No changes in loads of E-protein were found in ZIKV-infected C6/36 cells, when compounds were treated after infection. In addition, we tested bis(1,10-phenanthroline)copper(II) chloride ([Cu(phen) 2 ]Cl 2 , (compound 5) and tris(1,10-phenanthroline)cobalt(III) chloride ([Co(phen) 3 ]Cl 3 , (compound 6) that also showed enhanced DENV2 loads. Also, we found that copper(II) chloride dehydrate (CuCl 2 ·2H 2 O) or cobalt(II) chloride hexahydrate (CoCl 2 ·6H 2 O) alone had no effects as "free" cations

  14. Lightweight, Wearable Metal Rubber-Textile Sensor for In-Situ Lunar Autonomous Health Monitoring, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This NASA Phase II SBIR program would develop comfortable garments with multiple integrated sensor functions for the monitoring of astronauts during long duration...

  15. Exploring the metal coordination properties of the pyrimidine part of purine nucleobases: isomerization reactions in heteronuclear Pt(II)/Pd(II) of 9-methyladenine.

    Science.gov (United States)

    Ibáñez, Susana; Albertí, Francisca M; Sanz Miguel, Pablo J; Lippert, Bernhard

    2011-10-17

    The synthesis and characterization of three heteronuclear Pt(2)Pd(2) (4, 5) and PtPd(2) (6) complexes of the model nucleobase 9-methyladenine (9-MeA) is reported. The compounds were prepared by reacting [Pt(NH(3))(3)(9-MeA-N7)](ClO(4))(2) (1) with [Pd(en)(H(2)O)(2)](ClO(4))(2) at different ratios r between Pt and Pd, with the goal to probe Pd(II) binding to any of the three available nitrogen atoms, N1, N3, N6 or combinations thereof. Pd(II) coordination occurs at N1 and at the deprotonated N6 positions, yet not at N3. 4 and 5 are isomers of [{(en)Pd}(2){N1,N6-9-MeA(-)-N7)Pt(NH(3))(3)}(2)](ClO(4))(6)·nH(2)O, with a head-head orientation of the two bridging 9-MeA(-) ligands in 4 and a head-tail orientation in 5. 6 is [{(en)Pd}(2)(OH)(N1,N6-9MeA(-)-N7)Pt(NH(3))(3)](ClO(4))(4)·4H(2)O, hence a condensation product between [Pt(NH(3))(3)(9-MeA-N7)](2+) and a μ-OH bridged dinuclear (en)Pd-OH-Pd(en) unit, which connects the N1 and N6 positions of 9-MeA(-) in an intramolecular fashion. 4 and 5, which slowly interconvert in aqueous solution, display distinct structural differences such as significantly different intramolecular Pd···Pd contacts (3.124 0(16) Å in 4; 2.986 6(14) Å in 5), among others. Binding of (en)Pd(II) to the exocyclic N6 atom in 4 and 5 is accompanied by a large movement of Pd(II) out of the 9-MeA(-) plane and a trend to a further shortening of the C6-N6 bond as compared to free 9-MeA. The packing patterns of 4 and 5 reveal substantial anion-π interactions.

  16. $L_{0}$ Gradient Projection.

    Science.gov (United States)

    Ono, Shunsuke

    2017-04-01

    Minimizing L 0 gradient, the number of the non-zero gradients of an image, together with a quadratic data-fidelity to an input image has been recognized as a powerful edge-preserving filtering method. However, the L 0 gradient minimization has an inherent difficulty: a user-given parameter controlling the degree of flatness does not have a physical meaning since the parameter just balances the relative importance of the L 0 gradient term to the quadratic data-fidelity term. As a result, the setting of the parameter is a troublesome work in the L 0 gradient minimization. To circumvent the difficulty, we propose a new edge-preserving filtering method with a novel use of the L 0 gradient. Our method is formulated as the minimization of the quadratic data-fidelity subject to the hard constraint that the L 0 gradient is less than a user-given parameter α . This strategy is much more intuitive than the L 0 gradient minimization because the parameter α has a clear meaning: the L 0 gradient value of the output image itself, so that one can directly impose a desired degree of flatness by α . We also provide an efficient algorithm based on the so-called alternating direction method of multipliers for computing an approximate solution of the nonconvex problem, where we decompose it into two subproblems and derive closed-form solutions to them. The advantages of our method are demonstrated through extensive experiments.

  17. Efficient inclusion body processing using chemical extraction and high gradient magnetic fishing

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Choe, W.S.; Middelberg, A.P.J.

    2003-01-01

    of the product-loaded supports with the aid of high gradient magnetic fields. The manufacture and testing of two types of micron-sized nonporous superparamagnetic metal chelator particles derivatized with iminodiacetic acid is described. In small-scale adsorption studies conducted with a hexahistidine tagged...... at a 60-fold increased scale using the high gradient magnetic fishing (HGMF) system to collect loaded Cu2+-chelator particles following batch adsorption of L1. Over 70% of the initial Ll present was recovered within the HGMF rig in a highly clarified form in two batch elution cycles with an overall......In this study we introduce a radical new approach for the recovery of proteins expressed in the form of inclusion bodies, involving W chemical extraction from the host cells, (ii) adsorptive capture of the target protein onto small magnetic adsorbents, and (iii) subsequent rapid collection...

  18. THE CHEMICAL ABUNDANCES OF STARS IN THE HALO (CASH) PROJECT. II. A SAMPLE OF 14 EXTREMELY METAL-POOR STARS ,

    International Nuclear Information System (INIS)

    Hollek, Julie K.; Sneden, Christopher; Shetrone, Matthew; Frebel, Anna; Roederer, Ian U.; Beers, Timothy C.; Kang, Sung-ju; Thom, Christopher

    2011-01-01

    We present a comprehensive abundance analysis of 20 elements for 16 new low-metallicity stars from the Chemical Abundances of Stars in the Halo (CASH) project. The abundances have been derived from both Hobby-Eberly Telescope High Resolution Spectrograph snapshot spectra (R ∼15, 000) and corresponding high-resolution (R ∼35, 000) Magellan Inamori Kyocera Echelle spectra. The stars span a metallicity range from [Fe/H] from –2.9 to –3.9, including four new stars with [Fe/H] < –3.7. We find four stars to be carbon-enhanced metal-poor (CEMP) stars, confirming the trend of increasing [C/Fe] abundance ratios with decreasing metallicity. Two of these objects can be classified as CEMP-no stars, adding to the growing number of these objects at [Fe/H]< – 3. We also find four neutron-capture-enhanced stars in the sample, one of which has [Eu/Fe] of 0.8 with clear r-process signatures. These pilot sample stars are the most metal-poor ([Fe/H] ∼< –3.0) of the brightest stars included in CASH and are used to calibrate a newly developed, automated stellar parameter and abundance determination pipeline. This code will be used for the entire ∼500 star CASH snapshot sample. We find that the pipeline results are statistically identical for snapshot spectra when compared to a traditional, manual analysis from a high-resolution spectrum.

  19. Cyanide bridged hetero-metallic polymeric complexes: Syntheses, vibrational spectra, thermal analyses and crystal structures of complexes [M(1,2-dmi)2Ni(μ-CN)4]n (M = Zn(II) and Cd(II))

    Science.gov (United States)

    Kürkçüoğlu, Güneş Süheyla; Sayın, Elvan; Şahin, Onur

    2015-12-01

    Two cyanide bridged hetero-metallic complexes of general formula, [M(1,2-dmi)2Ni(μ-CN)4]n (1,2-dmi = 1,2-dimethylimidazole and M = Zn(II) or Cd(II)) have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal analyses and elemental analyses. The crystallographic analyses reveal that the complexes, [Zn(1,2-dmi)2Ni(μ-CN)4] (1) and [Cd(1,2-dmi)2Ni(μ-CN)4] (2), have polymeric 2D networks. In the complexes, four cyanide groups of [Ni(CN)4]2- coordinated to the adjacent M(II) ions and distorted octahedral geometries of complexes are completed by two nitrogen atoms of trans 1,2-dmi ligands. The structures of 1 and 2 are similar and linked via intermolecular hydrogen bonding, C-H⋯Ni interactions to give rise to 3D networks. Vibration assignments are given for all the observed bands and the spectral features also supported to the crystal structures of heteronuclear complexes. The FT-IR and Raman spectra of the complexes are very much consistent with the structural data presented.

  20. Separation of some metal ions using coupled transport supported liquid membranes

    International Nuclear Information System (INIS)

    Chaudhary, M.A.

    1993-01-01

    Liquid membrane extraction processes has become very popular due to their superiority in many ways over other separation techniques. In coupled transport membranes the metal ions can be transported across the membrane against their concentration gradient under the influence of chemical potential difference. Liquid membranes consisting of a carrier-cum-diluent, supported in microporous polymeric hydrophobic films have been studied for transport of metal ions like U(VI), Cr(VI), Be(II), V(V), Ti(IV), Zn(II), Cd(II), Hf(IV), W(VI), and Co(II). The present paper presents basic data with respect to flux and permeabilities of these metal ions across membranes based on experimental results and theoretical equations, using different carriers and diluents and provides a brief reference to possibility of such membranes for large scale applications. (author)

  1. Formulation of nano-ceramic filters used in separation of heavy metals . Part II: Zirconia ceramic filters

    International Nuclear Information System (INIS)

    Khalil, T.; Labib, Sh.; Abou EI-Nour, F.H.; Abdel-Kbalik, M.

    2007-01-01

    Zirconia ceramic filters are prepared using polymeric sol-gel process. An optimization of synthesis parameters was studied to give cracked free coated nano porous film with high performance quality. Zirconia ceramic filters are characterized to select tbe optimized conditions that give tbe suitable zirconia filter used in heavy metal separation. The ceramic filters were characterized using BET method for surface measurements, mercury porosimeter for pore size distribution analysis and coating thickness measurements, SEM for microstructural studies and atomic absorption spectrophotometer (AAS) for metal analysis. The results indicated that zirconia ceramic filters. show high separation performance for cadmium, cupper, iron, manganese and lead

  2. Adsorption and Oxidation of Aromatic Amines on Metal(II Hexacyanocobaltate(III Complexes: Implication for Oligomerization of Exotic Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Rachana Sharma

    2017-03-01

    Full Text Available Based on the hypothesis on the presence of double metal cyanides in the primordial oceans, a series of nano-sized metal(II hexacyanocobaltate(III (MHCCo with the general formula: M3[Co(CN6]2•xH2O (where M = Zn, Fe, Ni and Mn has been synthesized. Surface interaction of aromatic amines, namely aniline, 4-chloroaniline, 4-methylaniline and 4-methoxyaniline with MHCCo particles has been carried out at the concentration range of 100–400 μM at pH~7.0. The percentage binding of aromatic amines on MHCCo surface was found to be in the range of 84%–44%. The trend in adsorption was in accordance to the relative basicity of the studied amines. At the experimental pH, amines reacted rapidly with the surface of the iron(II hexacyanocobaltate, producing colored products that were analyzed by Gas Chromatography Mass Spectroscopy (GC-MS. GC-MS analysis of the colored products demonstrated the formation of dimers of the studied aromatic amines. Surface interaction of aromatic amines with MHCCo was studied by Fourier Transform Infrared (FT-IR spectroscopy and Field Emission Scanning Electron Microscopy (FE-SEM. The change in amine characteristic frequencies, as observed by FT-IR, suggests that interaction took place through the NH2 group on amines with metal ions of hexacyanocobaltate complexes. FE-SEM studies revealed the adherence of 4-methoxyaniline on zinc hexacyanocobaltate particles surface. We proposed that MHCCo might have been formed under the conditions on primitive Earth and may be regarded as an important candidate for concentrating organic molecules through the adsorption process.

  3. Adsorption and photocatalytic properties of transition metal Zinc(II) complex based on 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid

    Science.gov (United States)

    Qiao, Yu; Ren, Shan-Shan; Liu, Li-Hui; Guan, Wei-Sheng; Li, Zhi-Min; Che, Guang-Bo; Liu, Chun-Bo; Wang, Yan-Yan; Wang, Qing-Wei; Li, Xiu-Ying; Zhu, En-Wei

    2018-06-01

    A new coordination polymeric zinc(II) complex, namely, [Zn2(L)(H2O)3]n·nNO3(1), (H3L = 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid) has been synthesized under solvothermal conditions and structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction analysis and powder X-ray diffraction. Complex 1 exhibits a three-dimensional structure with a Schläfli symbol of 44•69•82 topologies, constructed from two crystallographically independent five and six coordinated mode with metal center and connected H3L ligands. The complex has good thermal stability and excellent photoluminescent property. Furthermore, by comparing the photoluminescent and photocatalytic mutation results induced by interconversion of metal ions, we confirm that the properties mutation induced by metal ions is much controllable and obvious. In addition, the complex exhibits significantly enhanced photocatalytic activity for methylene blue (MB) under UV light irradiation (λ < 400 nm), and the degradation rate could reach 75% in 80 min. Meanwhile trapping experiments indicated that the •O2- and h+ are the main activated species.

  4. Tetradentate-arm Schiff base derived from the condensation reaction of 3,3′-dihydroxybenzidine, glyoxal/diacetyl and 2-aminophenol: Designing, structural elucidation and properties of their binuclear metal(II complexes

    Directory of Open Access Journals (Sweden)

    E. Akila

    2017-05-01

    Full Text Available The novel binuclear Schiff base complexes were prepared by the reaction of 3,3′-dihydroxybenzidine, glyoxal/diacetyl and 2-aminophenol in 1:2:2 M ratio. The binucleating Schiff base ligand and its complexes of Cu(II, Ni(II and VO(II ions were characterized by elemental analysis, molar conductance, 1H NMR, infrared, electronic spectra, cyclic voltammetry, thermal, magnetic and EPR studies. The low molar conductance values of the complexes support the non-electrolytic in nature. In IR spectra, the comparison of shift in frequency of the complexes with the ligand reveals the coordination of donor atom to the metal atom. The binuclear nature of the complexes is assessed from their magnetic susceptibility values. The electronic and EPR spectra of the metal complexes provide information about the geometry of the complexes and are in good agreement with the proposed square planar geometry for Cu(II, Ni(II and square pyramidal for VO(II complexes. Molecular modeling has been used to suggest the structure of the complexes. The DNA cleavage ability of the complexes was monitored by gel electrophoresis using supercoiled pUC18 DNA. The metal complexes were screened for their antibacterial activities against pathogenic bacteria like Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Bacillus subtilis. The activity data show that the metal complexes are more potent activity than the parent Schiff base ligand against microorganisms.

  5. Synthesis, Characterization and Antimicrobial Studies of a New Mannich Base N-[Morpholino(phenylmethyl]acetamide and Its Cobalt(II, Nickel(II and Copper(II Metal Complexes

    Directory of Open Access Journals (Sweden)

    L. Muruganandam

    2012-01-01

    Full Text Available A new Mannich base N-[morpholino(phenylmethyl]acetamide (MBA, was synthesized and characterized by spectral studies. Chelates of MBA with cobalt(II, nickel(II and copper(II ions were prepared and characterized by elemental analyses, IR and UV spectral studies. MBA was found to act as a bidentate ligand, bonding through the carbonyl oxygen of acetamide group and CNC nitrogen of morpholine moiety in all the complexes. Based on the magnetic moment values and UV-Visible spectral data, tetracoordinate geometry for nitrato complexes and hexacoordinate geometry for sulphato complexes were assigned. The antimicrobial studies show that the Co(II nitrato complex is more active than the other complexes.

  6. On a New Theoretical Framework for RR Lyrae Stars. II. Mid-infrared Period–Luminosity–Metallicity Relations

    Energy Technology Data Exchange (ETDEWEB)

    Neeley, Jillian R.; Marengo, Massimo; Trueba, Nicolas [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Bono, Giuseppe; Braga, Vittorio F.; Magurno, Davide [Department of Physics, Università di Roma Tor Vergara, via della Ricerca Scientifica 1, I-00133 Roma (Italy); Dall’Ora, Massimo; Marconi, Marcella [INAF-Osservatorio Astronomico di Capodimonte, Salita Moiarello 16, I-80131 Napoli (Italy); Tognelli, Emanuele; Moroni, Pier G. Prada [Dipartimento di Fisica, Università di Pisa, Lago Bruno Pontecorvo 3, I-56127, Pisa (Italy); Beaton, Rachael L.; Madore, Barry F.; Seibert, Mark [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Freedman, Wendy L. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Monson, Andrew J. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Scowcroft, Victoria [Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Stetson, Peter B., E-mail: jrneeley@iastate.edu [NRC-Herzberg, Dominion Astrophysical Observatory, 5071 West Saanich Road, Victoria BC V9E 2E7 (Canada)

    2017-06-01

    We present new theoretical period–luminosity–metallicity (PLZ) relations for RR Lyræ stars (RRLs) at Spitzer and WISE wavelengths. The PLZ relations were derived using nonlinear, time-dependent convective hydrodynamical models for a broad range of metal abundances ( Z = 0.0001–0.0198). In deriving the light curves, we tested two sets of atmospheric models and found no significant difference between the resulting mean magnitudes. We also compare our theoretical relations to empirical relations derived from RRLs in both the field and in the globular cluster M4. Our theoretical PLZ relations were combined with multi-wavelength observations to simultaneously fit the distance modulus, μ {sub 0}, and extinction, A {sub V}, of both the individual Galactic RRL and of the cluster M4. The results for the Galactic RRL are consistent with trigonometric parallax measurements from Gaia ’ s first data release. For M4, we find a distance modulus of μ {sub 0} = 11.257 ± 0.035 mag with A {sub V}= 1.45 ± 0.12 mag, which is consistent with measurements from other distance indicators. This analysis has shown that, when considering a sample covering a range of iron abundances, the metallicity spread introduces a dispersion in the PL relation on the order of 0.13 mag. However, if this metallicity component is accounted for in a PLZ relation, the dispersion is reduced to ∼0.02 mag at mid-infrared wavelengths.

  7. A surface science study of model catalysts : II metal-support interactions in Cu/SiO2 model catalysts

    NARCIS (Netherlands)

    Oetelaar, van den L.C.A.; Partridge, A.; Toussaint, S.L.G.; Flipse, C.F.J.; Brongersma, H.H.

    1998-01-01

    The thermal stability of wet-chemically prepared Cu/SiO2 model catalysts containing nanometer-sized Cu particles on silica model supports was studied upon heating in hydrogen and ultrahigh vacuum. The surface and interface phenomena that occur are determined by the metal-support interactions.

  8. THE FATE OF TRACE METALS IN A ROTARY KILN INCINERATOR WITH A VENTURI/PACKED COLUMN SCRUBBER - VOLUME II: APPENDICES

    Science.gov (United States)

    A 5-week series of pilot-scale incineration tests, employing a synthetic waste feed, was performed at the U.S. Environmental Protection Agency's Incineration Research Facility to evaluate the fate of trace metals fed to a rotary kiln incinerator equipped with a venturi scrubber/p...

  9. A Plasmid Containing the Human Metallothionein II Gene Can Function as an Antibody-assisted Electrophoretic Biosensor for Heavy Metals

    Science.gov (United States)

    2015-01-16

    Biol. Chem. 273:7127–7133. Brugnera, E., Georgiev, O., Radtke , F., et al. 1994. Cloning, chromosomal mapping and characterization of the human metal...Signaling events for metallothionein induction. Mutat. Res. 533:211–226. Heuchel, R., Radtke , F., Georgiev, O., et al. 1994. The transcription factor MTF

  10. The effects of age on red giant metallicities derived from the near-infrared CaII triplet

    NARCIS (Netherlands)

    Cole, AA; Smecker-Hane, TA; Tolstoy, E; Bosler, TL; Gallagher, JS

    2004-01-01

    We have obtained spectra with a resolution of similar to2.5 Angstrom in the region of approximate to7500-9500 Angstrom for 116 red giants in five galactic globular clusters and six old open clusters (five with published metallicities and one previously unmeasured). The signal-to-noise (S/N) ratio

  11. Agricultural Construction Volume II. Oxy-Gas and Other Cutting/Welding Processes. Woodworking, Metals, Finishing. Instructor's Guide.

    Science.gov (United States)

    Admire, Myron; Maricle, Gary

    This guide contains instructor's materials for teaching a secondary agricultural construction course consisting of instructional units on oxy-gas and other cutting and welding processes (10 lessons), woodworking (6 lessons), metals (10 lessons), and finishing (4 lessons). The materials for each unit include student objectives, a list of…

  12. Ultrasound-assisted synthesis of nano-structured Zinc(II)-based metal-organic frameworks as precursors for the synthesis of ZnO nano-structures.

    Science.gov (United States)

    Bigdeli, Fahime; Ghasempour, Hosein; Azhdari Tehrani, Alireza; Morsali, Ali; Hosseini-Monfared, Hassan

    2017-07-01

    A 3D, porous Zn(II)-based metal-organic framework {[Zn 2 (oba) 2 (4-bpmn)]·(DMF) 1.5 } n (TMU-21), (4-bpmn=N,N'-Bis-pyridin-4-ylmethylene-naphtalene-1,5-diamine, H 2 oba=4,4'-oxybis(benzoic acid)) with nano-rods morphology under ultrasonic irradiation at ambient temperature and atmospheric pressure was prepared and characterized by scanning electron microscopy. Sonication time and concentration of initial reagents effects on the size and morphology of nano-structured MOFs were studied. Also {[Zn 2 (oba) 2 (4-bpmn)] (TMU-21) and {[Zn 2 (oba) 2 (4-bpmb)] (TMU-6), 4-bpmb=N,N'-(1,4-phenylene)bis(1-(pyridin-4-yl)methanimine) were easily prepared by mechanochemical synthesis. Nanostructures of Zinc(II) oxide were obtained by calcination of these compounds and their de-solvated analogue as activated MOFs, at 550°C under air atmosphere. As a result of that, different Nanostructures of Zinc(II) oxide were obtained. The ZnO nanoparticles were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and FT-IR spectroscopy. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Band gaps and photocurrent responses of two novel alkaline earth metal(II) complexes based on 4,5-di(4′-carboxylphenyl)benzene

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Jiang Ping; Yan, Zhi Shuo; Long, Ji Ying [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); Gong, Yun, E-mail: gongyun7211@cqu.edu.cn [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); Lin, Jian Hua, E-mail: jhlin@pku.edu.cn [Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2017-01-15

    By using a rigid dicarboxylate ligand, 4,5-di(4′-carboxylphenyl)benzene (H{sub 2}L), two complexes formulated as SrL(DMF)(H{sub 2}O)·(CH{sub 3}CN) (DMF=N,N′-dimethylformamide) (1) and BaL(H{sub 2}O){sub 2} (2) were solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complexes 1 and 2 display two-dimensional (2D) layer structures. The two complexes exhibit different electrochemical and photoelectrochemical properties. Their thermal stabilities, cyclic voltammograms, UV–vis absorption and diffuse reflectance spectra and photoluminescence properties have been investigated. The band structures, the total density of states (TDOS) and partial density of states (PDOS) of the two complexes were calculated by CASTEP program. Complex 2 exhibits much higher photocurrent density than complex 1. The Mott–Schottky plots reveal that complexes 1 and 2 both are p-type semiconductors, which are in agreement with their band structure calculations. - Graphical abstract: Two alkaline earth metal(II) complexes with 2D layer structures are p-type semiconductors, they possess different band structures and density of states. And the Ba(II) complex 2 exhibits much higher photocurrent density than the Sr(II) complex 1.

  14. Infrared multiple photon dissociation spectroscopy of group I and group II metal complexes with Boc-hydroxylamine

    NARCIS (Netherlands)

    Dain, R.P.; Gresham, G.; Groenewold, G.S.; Steill, J.D.; Oomens, J.; van Stipdonk, M.J.

    2013-01-01

    RATIONALE: Hydroxamates are essential growth factors for some microbes, acting primarily as siderophores that solubilize iron for transport into a cell. Here we determined the intrinsic structure of 1:1 complexes between Boc-protected hydroxylamine and group I ([M(L)](+)) and group II ([M(L-H)](+))

  15. Complexes of cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II) and dioxouranium(II) with thiophene-2-aldehydethiosemicarbazone

    International Nuclear Information System (INIS)

    Singh, Balwan; Misra, Harihar

    1986-01-01

    Metal complexes of thiosemicarbazides have been known for their pharmacological applications. Significant antitubercular, fungicidal and antiviral activities have been reported for thiosemicarbazides and their derivatives. The present study describes the systhesis and characterisation of complexes of Co II , Cu II , Zn II ,Cd II and UO II with thiosemicarbazone obtained by condensing thiophene-2-aldehyde with thiosemicarbazide. 17 refs., 2 tables. (author)

  16. On the gradient plasticity approach to size effects. Pt. 1: reviews

    International Nuclear Information System (INIS)

    Malmberg, T.; Tsagrakis, I.; Eleftheriadis, I.; Aifantis, E.C.; Michigan Technol. Univ., Houghton, MI

    2001-03-01

    The influence of specimen size on the plastic deformation and failure behaviour of some metals and steels is considered. This size dependence issue relates to the question of the transferability of mechanical test results of geometrically similar scaled-down structural models to the full scale structures using similitude laws; but it concerns also the validity of small scale laboratory type test results and their use as a basis for the computational modelling of large scale components. In part I ''reviews'' of this report a restricted review of scaled experiments at room temperature of geometrically similar specimens is given. This refers to the initiation of yielding under non-uniform states of deformation and also to the plastic deformation and fracture of smooth tensile specimens. Among others, non-classical continuum mechanics theories have become a means to interpret size effects. Especially gradient concepts are of interest which enrich the classical plasticity theories by higher order spatial strain gradients. These model extensions implicate additional material parameters which can be associated with internal length scales characteristic for the material. In part I a brief review of several gradient theories of plasticity is also given, including both deformation and flow theories and a comparison of the original ''symmetric stress'' theory with the more recent ''asymmetric stress'' theory is provided. The forthcoming part II ''applications'' exemplifies to what extend strain gradient models can describe the size influence on the deformation behaviour. (orig.) [de

  17. Surface Grafting of Ru(II) Diazonium-Based Sensitizers on Metal Oxides Enhances Alkaline Stability for Solar Energy Conversion.

    Science.gov (United States)

    Bangle, Rachel; Sampaio, Renato N; Troian-Gautier, Ludovic; Meyer, Gerald J

    2018-01-24

    The electrografting of [Ru(ttt)(tpy-C 6 H 4 -N 2 + )] 3+ , where "ttt" is 4,4',4″-tri-tert-butyl-2,2':6',2″-terpyridine, was investigated on several wide band gap metal oxide surfaces (TiO 2 , SnO 2 , ZrO 2 , ZnO, In 2 O 3 :Sn) and compared to structurally analogous sensitizers that differed only by the anchoring group, i.e., -PO 3 H 2 and -COOH. An optimized procedure for diazonium electrografting to semiconductor metal oxides is presented that allowed surface coverages that ranged between 4.7 × 10 -8 and 10.6 × 10 -8 mol cm -2 depending on the nature of the metal oxide. FTIR analysis showed the disappearance of the diazonium stretch at 2266 cm -1 after electrografting. XPS analysis revealed a characteristic peak of Ru 3d at 285 eV as well as a peak at 531.6 eV that was attributed to O 1s in Ti-O-C bonds. Photocurrents were measured to assess electron injection efficiency of these modified surfaces. The electrografted sensitizers exhibited excellent stability across a range of pHs spanning from 1 to 14, where classical binding groups such as carboxylic and phosphonic derivatives were hydrolyzed.

  18. The Chemical Abundances of Stars in the Halo (CASH) Project. II. A Sample of 14 Extremely Metal-poor Stars

    Science.gov (United States)

    Hollek, Julie K.; Frebel, Anna; Roederer, Ian U.; Sneden, Christopher; Shetrone, Matthew; Beers, Timothy C.; Kang, Sung-ju; Thom, Christopher

    2011-11-01

    We present a comprehensive abundance analysis of 20 elements for 16 new low-metallicity stars from the Chemical Abundances of Stars in the Halo (CASH) project. The abundances have been derived from both Hobby-Eberly Telescope High Resolution Spectrograph snapshot spectra (R ~15, 000) and corresponding high-resolution (R ~35, 000) Magellan Inamori Kyocera Echelle spectra. The stars span a metallicity range from [Fe/H] from -2.9 to -3.9, including four new stars with [Fe/H] ratios with decreasing metallicity. Two of these objects can be classified as CEMP-no stars, adding to the growing number of these objects at [Fe/H]CASH and are used to calibrate a newly developed, automated stellar parameter and abundance determination pipeline. This code will be used for the entire ~500 star CASH snapshot sample. We find that the pipeline results are statistically identical for snapshot spectra when compared to a traditional, manual analysis from a high-resolution spectrum. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen. Based on observations gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  19. Clonal variation in heavy metal accumulation and biomass production in a poplar coppice culture. II. Vertical distribution and phytoextraction potential

    International Nuclear Information System (INIS)

    Laureysens, I.; Temmerman, L. de; Hastir, T.; Gysel, M. van; Ceulemans, R.

    2005-01-01

    Short rotation coppice cultures (SRC) are intensively managed, high-density plantations of multi-shoot trees. In April 1996, an SRC field trial with 17 different poplar clones was established in Boom (Belgium) on a former waste disposal site. In December 1996 and January 2001, all shoots were cut back to a height of 5 cm to create a coppice culture. For six clones, wood and bark were sampled at the bottom, middle and top of a shoot in August and November 2002. No significant height effect of metal concentration was found, but for wood, metal concentrations generally increased toward the top of the shoot in August, and decreased toward the top of the shoot in November. Phytoextraction potential of a clone was primarily determined by metal concentration and by biomass production. Shoot size and number of shoots per stool were less important, as a high biomass production could be achieved by producing a few large shoots or many smaller shoots. Clone Fritzi Pauley accumulated 1.4 kg ha -1 of Al over two years; Wolterson and Balsam Spire showed a relatively high accumulation of Cd and Zn, i.e. averaging, respectively 47 and 57 g ha -1 for Cd and 2.4 and 2.0 kg ha -1 for Zn over two years. - Poplar shows potential for phytoextraction of Al, Cd and Zn on slightly contaminated soils

  20. Clonal variation in heavy metal accumulation and biomass production in a poplar coppice culture. II. Vertical distribution and phytoextraction potential

    Energy Technology Data Exchange (ETDEWEB)

    Laureysens, I. [University of Antwerp, Campus Drie Eiken, Department of Biology, Universiteitsplein 1, B-2610 Wilrijk (Belgium)]. E-mail: ilse.laureysens@ua.ac.be; Temmerman, L. de [Veterinary and Agrochemical Research Centre (VAR), Leuvensesteenweg 17, B-3080 Tervuren (Belgium); Hastir, T. [University of Antwerp, Campus Drie Eiken, Department of Biology, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Gysel, M. van [University of Antwerp, Campus Drie Eiken, Department of Chemistry, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Ceulemans, R. [University of Antwerp, Campus Drie Eiken, Department of Biology, Universiteitsplein 1, B-2610 Wilrijk (Belgium)

    2005-02-01

    Short rotation coppice cultures (SRC) are intensively managed, high-density plantations of multi-shoot trees. In April 1996, an SRC field trial with 17 different poplar clones was established in Boom (Belgium) on a former waste disposal site. In December 1996 and January 2001, all shoots were cut back to a height of 5 cm to create a coppice culture. For six clones, wood and bark were sampled at the bottom, middle and top of a shoot in August and November 2002. No significant height effect of metal concentration was found, but for wood, metal concentrations generally increased toward the top of the shoot in August, and decreased toward the top of the shoot in November. Phytoextraction potential of a clone was primarily determined by metal concentration and by biomass production. Shoot size and number of shoots per stool were less important, as a high biomass production could be achieved by producing a few large shoots or many smaller shoots. Clone Fritzi Pauley accumulated 1.4 kg ha{sup -1} of Al over two years; Wolterson and Balsam Spire showed a relatively high accumulation of Cd and Zn, i.e. averaging, respectively 47 and 57 g ha{sup -1} for Cd and 2.4 and 2.0 kg ha{sup -1} for Zn over two years. - Poplar shows potential for phytoextraction of Al, Cd and Zn on slightly contaminated soils.

  1. The Wilson-Bappu effect of the MgII k line - dependence on stellar temperature, activity and metallicity

    DEFF Research Database (Denmark)

    Elgaroy, O.; Engvold, O.; Lund, Niels

    1999-01-01

    widths around the regression lines. The sample contains slowly rotating stars of different activity levels and is suitable for investigations of a possible relation between line width and stellar activity. A difference in behavior between dwarfs and giants (and supergiants) of spectral class K seems......The Wilson-Bappu effect is investigated using accurate absolute magnitudes of 65 stars obtained through early release of data from the Hipparcos satellite together with MgII k fine widths determined from high resolution spectra observed with the International Ultraviolet Explorer (IUE) observatory....... Stars of spectral classes F, G, K and M and luminosity classes I-V are represented in the sample. Wilson-Bappu relations for the Mg II k line for stars of different temperatures i.e. spectral classes are determined. The relation varies with spectral class and there is a significant scatter of the line...

  2. Synthesis and Luminescence Properties of New Metal-Organic Frameworks Based on Zinc(II Ions and 2,5-Thiophendicarboxylate Ligands

    Directory of Open Access Journals (Sweden)

    Anna Lysova

    2017-12-01

    Full Text Available Six new metal-organic frameworks based on 2,5-thiophendicarboxylate (tdc2– and zinc(II ions were prepared in different reaction conditions, and their crystal structures were determined by XRD analysis. The compound [Zn(tdc(dabco(H2O]∙DMF (1 is based on mononuclear Zn(II ions connected by tdc2– and dabco linkers into square-grid layered nets. The compound [Zn3(tdc3(dabco2] (2 is a rare example of monocoordinated dabco ligands in the metal-organic framework chemistry. Its crystal structure contains trinuclear linear carboxylate building units, connected into a distorted primitive cubic net. Similar trinuclear units were also found in [Zn5(tdc4(Htdc2(dabco2]∙4DMF∙14H2O (3, although as a part of more complicated pentanuclear motives. The compound [Na2Zn(tdc2(DMF2] (4, quantitatively isolated by the addition of NaOH to the mixture of Zn(NO32 and H2tdc, is based on 1D chain motives, interconnected by tdc2– linkers into a three-dimensional framework. The compounds [Zn3(tdc3(DMF2]∙0.8DMF∙1.1H2O (5 and [Zn3(tdc3(DMF3]∙0.8DMF∙1.3H2O (6 were prepared in very similar reaction conditions, but with different times of heating, indirectly indicating higher thermodynamic stability of the three-dimensional metal-organic framework 6, compared to the two-dimensional metal-organic framework 5. The crystal structures of both 5 and 6 are based on the same trinuclear linear units as in 2. Luminescence properties of the compounds 4–6 were studied and compared with those for Na2tdc salt. In particular, the luminescence spectra of 4 practically coincide with those for the reference Na2tdc, while 5 and 6 exhibit coherent shifts of peaks to higher energies. Such hypsochromic shifts are likely associated with a different effective charge on the tdc2– anions in Na2tdc and sodium-containing 4, compared to zinc-based 5 and 6.

  3. Pb II

    African Journals Online (AJOL)

    Windows User

    This investigation describes the use of non-living biomass of Aspergillus caespitosus for removal of ... Pb(II) production has exceeded 3.5 million tons per year. It has been used in the ... This biomass was selected after screening a wide range of microbes. .... prolonged, which proved better biopolymer in metal uptake (Gadd ...

  4. Travelling gradient thermocouple calibration

    International Nuclear Information System (INIS)

    Broomfield, G.H.

    1975-01-01

    A short discussion of the origins of the thermocouple EMF is used to re-introduce the idea that the Peltier and Thompson effects are indistinguishable from one another. Thermocouples may be viewed as devices which generate an EMF at junctions or as integrators of EMF's developed in thermal gradients. The thermal gradient view is considered the more appropriate, because of its better accord with theory and behaviour, the correct approach to calibration, and investigation of service effects is immediately obvious. Inhomogeneities arise in thermocouples during manufacture and in service. The results of travelling gradient measurements are used to show that such effects are revealed with a resolution which depends on the length of the gradient although they may be masked during simple immersion calibration. Proposed tests on thermocouples irradiated in a nuclear reactor are discussed

  5. Quaternion Gradient and Hessian

    OpenAIRE

    Xu, Dongpo; Mandic, Danilo P.

    2014-01-01

    The optimization of real scalar functions of quaternion variables, such as the mean square error or array output power, underpins many practical applications. Solutions typically require the calculation of the gradient and Hessian. However, real functions of quaternion variables are essentially nonanalytic, which are prohibitive to the development of quaternion-valued learning systems. To address this issue, we propose new definitions of quaternion gradient and Hessian, based on the novel gen...

  6. Complexation of nitrogen and sulphur donor Schiff's base ligand to Cr(III) and Ni(II) metal ions: Synthesis, spectroscopic and antipathogenic studies

    Science.gov (United States)

    Sharma, Amit Kumar; Chandra, Sulekh

    2011-01-01

    2,6-Diacetyl pyridine based ligand was synthesized by the reaction of 2,6-diacetyl pyridine with thiocarbohydrazide in presence of acetic acid. The coordination compounds with Cr(III) and Ni(II) metal ions having [Cr(L)X]X 2 and [Ni(L)X]X compositions (where L = ligand and X = NO 3-, Cl - and CH 3COO -) were synthesized and characterized by physicochemical and spectral studies. The studies like elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, UV-Vis, NMR, mass and EPR reveal that the complexes are octahedral. The compounds were examined against the pathogenic fungal and bacterial strains like Alternaria brassicae, Aspergillus niger, Fusarium oxysporum, Xanthomonas compestris and Pseudomonas aeruginosa. A. niger causes the diseases Apergillosis and Otomycosis in humans.

  7. New Nuclear Materials Including Non Metallic Fuel Elements. Vol. II. Proceedings of the Conference on New Nuclear Materials Technology, Including Non Metallic Fuel Elements

    International Nuclear Information System (INIS)

    1963-01-01

    One of the major aims of the International Atomic Energy Agency in furthering the peaceful uses of atomic energy is to encourage the development of economical nuclear power. Certainly, one of the more obvious methods of producing economical nuclear power is the development of economical fuels that can be used at high temperatures for long periods of time, and which have sufficient strength and integrity to operate under these conditions without permitting the release of fission products. In addition it is desirable that after irradiation these new fuels be economically reprocessed to reduce further the cost of the fuel cycle. As nuclear power becomes more and more competitive with conventional power the interest in new and more efficient higher-temperature fuels naturally increases rapidly. For these reasons, the Agency organized a Conference on New Nuclear Materials Technology, Including Non-Metallic Fuel Elements, which was held from 1 to 5 July 1963 at the International Hotel, Prague, with the assistance and co-operation of the Government of the Czechoslovak Socialist Republic. A total of 151 scientists attended, from 23 countries and 4 international organizations. The participants heard and discussed more than 60 scientific papers. The Agency wishes to thank the scientists who attended this Conference for their papers and for many spirited discussions that truly mark a successful meeting. The Agency wishes also to record its gratitude for the assistance and generous hospitality accorded the Conference, the participants and the Agency's staff by the Government of the Czechoslovak Socialist Republic and by the people of Prague. The scientific information contained in these Proceedings should help to quicken the pace of progress in the fabrication of new and m ore economical fuels, and it is hoped that these proceedings will be found useful to all workers in this and related fields

  8. Pregalactic helium abundance and abundance gradients across our galaxy from planetary nebulae

    Energy Technology Data Exchange (ETDEWEB)

    D' Odorico, S; Peimbert, M [Universidad Nacional Autonoma de Mexico, Mexico City. Instituto de Astronomia; Sabbadin, F [Padua Univ. (Italy). Istituto di Astronomia

    1976-03-01

    From the observations of planetary nebulae by Peimbert and Torres-Peimbert we have studied the radial gradients across our galaxy of the helium, oxygen and nitrogen abundance relative to hydrogen. The increase of the oxygen to hydrogen abundance ratio from a radial distance to the galactic center of 14 to 8 kpc is about a factor of 3 while that of the nitrogen to hydrogen ratio is about twice as large. By adopting oxygen as representative of the heavy elements it is found that the helium enrichment is coupled to the heavy metal enrichment by ..delta..Y/..delta..Zapproximately2.9 in close agreement with the value derived from H II regions. The pregalactic N(He)/N(H) value derived from planetary nebulae is 0.073+-0.008 also in agreement with the value derived from H II regions.

  9. EVOLUTION, NUCLEOSYNTHESIS, AND YIELDS OF LOW-MASS ASYMPTOTIC GIANT BRANCH STARS AT DIFFERENT METALLICITIES. II. THE FRUITY DATABASE

    International Nuclear Information System (INIS)

    Cristallo, S.; Domínguez, I.; Abia, C.; Piersanti, L.; Straniero, O.; Gallino, R.; Di Rico, G.; Quintini, M.; Bisterzo, S.

    2011-01-01

    By using updated stellar low-mass stars models, we systematically investigate the nucleosynthesis processes occurring in asymptotic giant branch (AGB) stars. In this paper, we present a database dedicated to the nucleosynthesis of AGB stars: FRANEC Repository of Updated Isotopic Tables and Yields (FRUITY). An interactive Web-based interface allows users to freely download the full (from H to Bi) isotopic composition, as it changes after each third dredge-up (TDU) episode and the stellar yields the models produce. A first set of AGB models, having masses in the range 1.5 ≤M/M ☉ ≤ 3.0 and metallicities 1 × 10 –3 ≤ Z ≤ 2 × 10 –2 , is discussed. For each model, a detailed description of the physical and the chemical evolution is provided. In particular, we illustrate the details of the s-process and we evaluate the theoretical uncertainties due to the parameterization adopted to model convection and mass loss. The resulting nucleosynthesis scenario is checked by comparing the theoretical [hs/ls] and [Pb/hs] ratios to those obtained from the available abundance analysis of s-enhanced stars. On the average, the variation with the metallicity of these spectroscopic indexes is well reproduced by theoretical models, although the predicted spread at a given metallicity is substantially smaller than the observed one. Possible explanations for such a difference are briefly discussed. An independent check of the TDU efficiency is provided by the C-stars luminosity function. Consequently, theoretical C-stars luminosity functions for the Galactic disk and the Magellanic Clouds have been derived. We generally find good agreement with observations.

  10. Observational Constraints on First-Star Nucleosynthesis. II. Spectroscopy of an Ultra metal-poor CEMP-no Star

    Science.gov (United States)

    Placco, Vinicius M.; Frebel, Anna; Beers, Timothy C.; Yoon, Jinmi; Chiti, Anirudh; Heger, Alexander; Chan, Conrad; Casey, Andrew R.; Christlieb, Norbert

    2016-12-01

    We report on the first high-resolution spectroscopic analysis of HE 0020-1741, a bright (V = 12.9), ultra metal-poor ([{Fe}/{{H}}] = -4.1), carbon-enhanced ([{{C}}/{Fe}] = +1.7) star selected from the Hamburg/ESO Survey. This star exhibits low abundances of neutron-capture elements ([{Ba}/{Fe}] = -1.1) and an absolute carbon abundance A(C) = 6.1 based on either criterion, HE 0020-1741 is subclassified as a carbon-enhanced metal-poor star without enhancements in neutron-capture elements (CEMP-no). We show that the light-element abundance pattern of HE 0020-1741 is consistent with predicted yields from a massive (M = 21.5 {M}⊙ ), primordial-composition, supernova (SN) progenitor. We also compare the abundance patterns of other ultra metal-poor stars from the literature with available measures of C, N, Na, Mg, and Fe abundances with an extensive grid of SN models (covering the mass range 10{--}100 {M}⊙ ), in order to probe the nature of their likely stellar progenitors. Our results suggest that at least two classes of progenitors are required at [{Fe}/{{H}}] \\lt -4.0, as the abundance patterns for more than half of the sample studied in this work (7 out of 12 stars) cannot be easily reproduced by the predicted yields. Based on observations gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile, and the New Technology Telescope (NTT) of the European Southern Observatory (088.D-0344A), La Silla, Chile.

  11. Evolution, Nucleosynthesis, and Yields of Low-mass Asymptotic Giant Branch Stars at Different Metallicities. II. The FRUITY Database

    Science.gov (United States)

    Cristallo, S.; Piersanti, L.; Straniero, O.; Gallino, R.; Domínguez, I.; Abia, C.; Di Rico, G.; Quintini, M.; Bisterzo, S.

    2011-12-01

    By using updated stellar low-mass stars models, we systematically investigate the nucleosynthesis processes occurring in asymptotic giant branch (AGB) stars. In this paper, we present a database dedicated to the nucleosynthesis of AGB stars: FRANEC Repository of Updated Isotopic Tables & Yields (FRUITY). An interactive Web-based interface allows users to freely download the full (from H to Bi) isotopic composition, as it changes after each third dredge-up (TDU) episode and the stellar yields the models produce. A first set of AGB models, having masses in the range 1.5 3.0 and metallicities 1 × 10-3 <= Z <= 2 × 10-2, is discussed. For each model, a detailed description of the physical and the chemical evolution is provided. In particular, we illustrate the details of the s-process and we evaluate the theoretical uncertainties due to the parameterization adopted to model convection and mass loss. The resulting nucleosynthesis scenario is checked by comparing the theoretical [hs/ls] and [Pb/hs] ratios to those obtained from the available abundance analysis of s-enhanced stars. On the average, the variation with the metallicity of these spectroscopic indexes is well reproduced by theoretical models, although the predicted spread at a given metallicity is substantially smaller than the observed one. Possible explanations for such a difference are briefly discussed. An independent check of the TDU efficiency is provided by the C-stars luminosity function. Consequently, theoretical C-stars luminosity functions for the Galactic disk and the Magellanic Clouds have been derived. We generally find good agreement with observations.

  12. 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.

  13. A Copper(II)-Paddlewheel Metal-Organic Framework with Exceptional Hydrolytic Stability and Selective Adsorption and Detection Ability of Aniline in Water.

    Science.gov (United States)

    Chen, Ya; Wang, Bin; Wang, Xiaoqing; Xie, Lin-Hua; Li, Jinping; Xie, Yabo; Li, Jian-Rong

    2017-08-16

    Copper(II)-paddlewheel-based metal-organic frameworks (CP-MOFs) represent a unique subclass of MOFs with highly predictable porous structures, facile syntheses, and functional open metal sites. However, the lack of high hydrolytic stability is an obstacle for CP-MOFs in many practical applications. In this work, we report a new CP-MOF, [Cu 4 (tdhb)] (BUT-155), which is constructed from a judiciously designed carboxylate ligand with high coordination connectivity (octatopic), abundant hydrophobic substituents (six methyl groups), and substituent constrained geometry (tetrahedral backbone), tdhb 8- [H 8 tdhb = 3,3',5,5'-tetrakis(3,5-dicarboxyphenyl)-2,2',4,4',6,6'-hexamethylbiphenyl)]. BUT-155 shows high porosity with a Brunauer-Emmett-Teller surface area of 2070 m 2 /g. Quite interestingly, this CP-MOF retains its structural integrity after being treated in water for 10 days at room temperature or in boiling water for 24 h. To the best of our knowledge, BUT-155 represents the first CP-MOF that is demonstrated to retain its structural integrity in boiling water. The high hydrolytic stability of BUT-155 allowed us to carry out adsorption studies of water vapor and aqueous organic pollutants on it. Water-vapor adsorption reveals a sigmoidal isotherm and a high uptake (46.7 wt %), which is highly reversible and regenerable. In addition, because of the availability of soft-acid-type open Cu(II) sites, BUT-155 shows a high performance for selective adsorption of soft-base-type aniline over water or phenol, and a naked-eye detectable color change for the MOF sample accompanies this. The adsorption selectivity and high adsorption capacity of aniline in BUT-155 are also well-interpreted by single-crystal structures of the water- and aniline-included phases of BUT-155.

  14. CSER 94-014: Storage of metal-fuel loaded EBR-II casks in concrete vault on PFP grounds

    International Nuclear Information System (INIS)

    Hess, A.L.

    1994-01-01

    A criticality safety evaluation is presented to permit EBR-2 spent fuel casks loaded with metallic fuel rods to be stored in an 8-ft diameter, cylindrical concrete vault inside the PFP security perimeter. The specific transfer of three casks with Pu alloy fuel from the Los Alamos Molten Plutonium Reactor Experiment from the burial grounds to the vault is thus covered. Up to seven casks may be emplaced in the casing with 30 inches center to center spacing. Criticality safety is assured by definitive packaging rules which keep the fissile medium dry and at a low effective volumetric density

  15. FT-IR Spectroscopic study on the 4-(3-Cyclohexen-1-yl)pyridine metal (II) tetracyanonickelate complex

    International Nuclear Information System (INIS)

    Parlak, C.

    2005-01-01

    New Hofmann type complex in the form of M(4-Chpy) 2 Ni(CN) 4 (where 4-Chpy=4-(3- Cyclohexen-1-yl)pyridine and M = Ni) was prepared in powder form and its infrared spectra is reported in the range of 4000-400 cm - 1. The spectral findings suggest that this compound is similar in structure to the Hofmann type complexes and its structure consists of polymeric layers | M-Ni(CN) 4 |∞ with the 4-(3-Cyclohexen-1-yl)pyridine molecule bound to the metal atom (M)

  16. Metal derivatives of organo-phosphorous compounds. Part II : niobium(V) and tantalum(V) derivatives

    International Nuclear Information System (INIS)

    Puri, D.M.; Singh, Soran

    1981-01-01

    Reactions between niobium(V) chloride, tantalum(V) chloride and dialkyl/diaryl (Et-, Prsup(i)-, Busup(n)- and Ph-) phosphites have been studied in different molar ratios and under different conditions of temperature and solvent systems. The isolated complex compounds have been characterised on the basis of infrared spectral measurements, elemental analyses and magnetic susceptibility data. The polymeric nature of the products has been indicated by their molecular weights. The coordination of phosphite units to metal atom of the other molecule through phosphoryl oxygen gave rise to O-P-O-bridges. (author)

  17. Methods for Fabricating Gradient Alloy Articles with Multi-Functional Properties

    Science.gov (United States)

    Hofmann, Douglas C. (Inventor); Borgonia, John Paul C. (Inventor); Dillon, Robert P. (Inventor); Suh, Eric J. (Inventor); Mulder, Jerry L. (Inventor); Gardner, Paul B. (Inventor)

    2015-01-01

    Systems and methods for fabricating multi-functional articles comprised of additively formed gradient materials are provided. The fabrication of multi-functional articles using the additive deposition of gradient alloys represents a paradigm shift from the traditional way that metal alloys and metal/metal alloy parts are fabricated. Since a gradient alloy that transitions from one metal to a different metal cannot be fabricated through any conventional metallurgy techniques, the technique presents many applications. Moreover, the embodiments described identify a broad range of properties and applications.

  18. Gradient Alloy for Optical Packaging

    Data.gov (United States)

    National Aeronautics and Space Administration — Advances in additive manufacturing, such as Laser Engineered Net Shaping (LENS), enables the fabrication of compositionally gradient microstructures, i.e. gradient...

  19. The Chemical Abundances of Stars in the Halo (CASH) Project. II. New Extremely Metal-poor Stars

    Science.gov (United States)

    Krugler, Julie A.; Frebel, A.; Roederer, I. U.; Sneden, C.; Shetrone, M.; Beers, T.; Christlieb, N.

    2011-01-01

    We present new abundance results from the Chemical Abundances of Stars in the Halo (CASH) project. The 500 CASH spectra were observed using the Hobby-Eberly Telescope in "snapshot" mode and are analyzed using an automated stellar parameter and abundance pipeline called CASHCODE. For the 20 most metal-poor stars of the CASH sample we have obtained high resolution spectra using the Magellan Telescope in order to test the uncertainties and systematic errors associated with the snapshot quality (i.e., R 15,000 and S/N 65) HET spectra and to calibrate the newly developed CASHCODE by making a detailed comparison between the stellar parameters and abundances determined from the high resolution and snapshot spectra. We find that the CASHCODE stellar parameters (effective temperature, surface gravity, metallicity, and microturbulence) agree well with the results of the manual analysis of the high resolution spectra. We present the abundances of three newly discovered stars with [Fe/H] ratios with alpha-enhancement and Fe-peak depletion and a range of n-capture elements. The full CASH sample will be used to derive statistically robust abundance trends and frequencies (e.g. carbon and n-capture), as well as placing constraints on nucleosynthetic processes that occurred in the early universe.

  20. Electrogenerated Chemiluminescence Behavior of Au nanoparticles-hybridized Pb (II) metal-organic framework and its application in selective sensing hexavalent chromium.

    Science.gov (United States)

    Ma, Hongmin; Li, Xiaojian; Yan, Tao; Li, Yan; Liu, Haiyang; Zhang, Yong; Wu, Dan; Du, Bin; Wei, Qin

    2016-02-23

    In this work, a novel electrochemiluminescence (ECL) sensor based on Au nanoparticles-hybridized Pb (II)-β-cyclodextrin (Pb-β-CD) metal-organic framework for detecting hexavalent chromium (Cr(VI)) was developed. Pb-β-CD shows excellent ECL behavior and unexpected reducing ability towards Au ions. Au nanoparticles could massively form on the surface of Pb-β-CD (Au@Pb-β-CD) without use of any additional reducing agent. In the presence of coreactant K2S2O8, the ECL emission of Pb-β-CD was enhanced by the formation of Au nanoparticles. Cr(VI) can collisionally quench the ECL behavior of Au@Pb-β-CD/S2O8(2-) system and the detection mechanism was investigated. This ECL sensor is found to have a linear response in the range of 0.01-100 μM and a low detection limit of 3.43 nM (S/N = 3) under the optimal conditions. These results suggest that metal-organic framework Au@Pb-β-CD has great potential in extending the application in the ECL field as an efficient luminophore.

  1. Ligand design for alkali-metal-templated self-assembly of unique high-nuclearity CuII aggregates with diverse coordination cage units: crystal structures and properties.

    Science.gov (United States)

    Du, Miao; Bu, Xian-He; Guo, Ya-Mei; Ribas, Joan

    2004-03-19

    The construction of two unique, high-nuclearity Cu(II) supramolecular aggregates with tetrahedral or octahedral cage units, [(mu(3)-Cl)[Li subset Cu(4)(mu-L(1))(3)](3)](ClO(4))(8)(H(2)O)(4.5) (1) and [[Na(2) subset Cu(12)(mu-L(2))(8)(mu-Cl)(4)](ClO(4))(8)(H(2)O)(10)(H(3)O(+))(2)](infinity) (2) by alkali-metal-templated (Li(+) or Na(+)) self-assembly, was achieved by the use of two newly designed carboxylic-functionalized diazamesocyclic ligands, N,N'-bis(3-propionyloxy)-1,4-diazacycloheptane (H(2)L(1)) or 1,5-diazacyclooctane-N,N'-diacetate acid (H(2)L(2)). Complex 1 crystallizes in the trigonal R3c space group (a = b = 20.866(3), c = 126.26(4) A and Z = 12), and 2 in the triclinic P1 space group (a = 13.632(4), b = 14.754(4), c = 19.517(6) A, alpha = 99.836(6), beta = 95.793(5), gamma = 116.124(5) degrees and Z = 1). By subtle variation of the ligand structures and the alkali-metal templates, different polymeric motifs were obtained: a dodecanuclear architecture 1 consisting of three Cu(4) tetrahedral cage units with a Li(+) template, and a supramolecular chain 2 consisting of two crystallographically nonequivalent octahedral Cu(6) polyhedra with a Na(+) template. The effects of ligand functionality and alkali metal template ions on the self-assembly processes of both coordination supramolecular aggregates, and their magnetic behaviors are discussed in detail.

  2. Noncovalent functionalization of pristine CVD single-walled carbon nanotubes with 3d metal(II) phthalocyanines by adsorption from the gas phase

    Science.gov (United States)

    Basiuk, Vladimir A.; Flores-Sánchez, Laura J.; Meza-Laguna, Victor; Flores-Flores, José Ocotlán; Bucio-Galindo, Lauro; Puente-Lee, Iván; Basiuk, Elena V.

    2018-04-01

    Noncovalent hybrids of carbon nanotubes (CNTs) with phthalocyanines (Pcs) is a subject of growing research effort focused on the development of new efficient organic photovoltaic cells, heterogeneous catalysts, lithium batteries, gas sensors, field effect transistors, among other possible applications. The main advantage of using unsubstituted Pcs is their very moderate cost and easy commercial availability. Unfortunately, the deposition of unsubstituted Pcs onto CNT sidewalls via the traditional liquid-phase strategy proves to be very problematic due to an extremely poor solubility of Pcs. At the same time, unsubstituted free-base H2Pc ligand and many of its transition metal complexes exhibit high thermal stability and volatility under reduced pressure, which allows for their physical vapor deposition onto solid surfaces. In the present work, we demonstrated the possibility of simple, fast, efficient and environmentally friendly noncovalent functionalization of single-walled CNTs (SWNTs) with a series of 3d metal(II) phthalocyanines Me(II)Pc, where Me = Co, Ni, Cu and Zn. The functionalization can be performed at 400-500 °C under moderate vacuum, and takes about 2-3 h only. The nanohybrids obtained were characterized by means of Fourier-transform infrared, Raman, UV-vis and energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), scanning and transmission electron microscopy. TGA suggested that Pc weight content is 30%, 17% and 35% for NiPc, CuPc and ZnPc, respectively (CoPc exhibited anomalous behavior), which is close to the estimates from EDS spectra of 24-39%, 27-36% and 27-44% for CoPc, CuPc and ZnPc, respectively. A strong increase in intensity of D band in the Raman spectra of SWNT‒Pc hybrids, as compared to that of pristine nanotubes, was interpreted as very strong interactions between Pc molecules and SWNT sidewalls. Very high absolute values of binding energies of 32.46-37.12 kcal/mol and the patterns of HOMO and LUMO distribution

  3. High Gradient Accelerator Research

    International Nuclear Information System (INIS)

    Temkin, Richard

    2016-01-01

    The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low-power microwave cold test and high-power, high-gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

  4. Trigonal Prismatic Tris-pyridineoximate Transition Metal Complexes: A Cobalt(II) Compound with High Magnetic Anisotropy.

    Science.gov (United States)

    Pavlov, Alexander A; Savkina, Svetlana A; Belov, Alexander S; Nelyubina, Yulia V; Efimov, Nikolay N; Voloshin, Yan Z; Novikov, Valentin V

    2017-06-19

    High magnetic anisotropy is a key property of paramagnetic shift tags, which are mostly studied by NMR spectroscopy, and of single molecule magnets, for which magnetometry is usually used. We successfully employed both these methods in analyzing magnetic properties of a series of transition metal complexes, the so-called clathrochelates. A cobalt complex was found to be both a promising paramagnetic shift tag and a single molecule magnet because of it having large axial magnetic susceptibility tensor anisotropy at room temperature (22.5 × 10 -32 m 3 mol -1 ) and a high effective barrier to magnetization reversal (up to 70.5 cm -1 ). The origin of this large magnetic anisotropy is a negative value of zero-field splitting energy that reaches -86 cm -1 according to magnetometry and NMR measurements.

  5. Characteristics of tree bark as an indicator in high-immission areas : II. Contents of heavy metals.

    Science.gov (United States)

    Lötschert, W; Köhm, H -J

    1978-01-01

    1. Studies on indicator characteristics of bark of deciduous trees have been continued by measuring accumulation of Pb, Cd, Ni and Mn in the bark of Fraxinus excelsior at 34 sampling sites over an area of 150 km 2 in the immission area of Frankfurt am Main. 2. Iso-lines of equal Pb-contamination have been found. They include zones of graduated immissions. The pattern of these zones shows an eccentrical orientation and is the result of the distribution of the main traffic roads. A significant correlation of Pb in the bark and traffic congestion has been found. 3. The zones of Cd-contamination stretch from SW to NE. The orientation of these zones is determined by the distribution of the big emittenrs and the centers of heating power in the area and the predominating direction of wind. 4. A correlation between the accumulation of Pb and Cd has been detected. It is less significant than that between pH-value and sulfur content in the bark of trees in former investigations. 5. The distribution of Pb and Mn is antagonistic in the bark of Fraxinus excelsior and parallel in the needles of Taxus baccata. The content of Mn in the bark of Fraxinus is low. It must be accepted that this is partly an effect of elution by sulfur acid-aerosol formation. 6. The strongest accumulation of heavy metal immissions is found in mosses on the ground, mainly in Bryum argenteum. Nevertheless the bark of Fraxinus excelsior has shown consequently its accumulation characteristics as a good immission indicator for heavy metal contaminations by traffic and big emittents.

  6. A luminescent Cd(II)-based metal-organic framework for detection of Fe(III) ions in aqueous solution

    Science.gov (United States)

    Li, Fen-Fang; Zhu, Miao-Li; Lu, Li-Ping

    2018-05-01

    A novel Cd((II)-organic framework [Cd(Hcbic)]n (H3cbic = 1-(4-carboxybenz-yl)-1H-benzoim-idazole-5, 6-dicarboxylic acid) was assembled and characterized by X-ray single crystal analysis. The Cd-MOF features one-dimensional left and right-handed double helical chains with screw-pitch of about 4.727 Å and the 4-methyl benzoic acid groups of Hcbic2- ligands in MOF-1 play many ribbons distributing in the two sides of the 2D networks. It is found that MOF-1 shows high selectivity (KSV = 1.8 × 105 L / mol) for Fe3+ ions in water solution with luminescent quenching because of the existence of uncoordinated carboxyl groups within open frameworks, which indicates that MOF-1 is a simple and reliable detection sensing reagent for Fe3+ in practical applications.

  7. First-principles calculations of the II-VI semiconductor β-HgS: Metal or semiconductor

    International Nuclear Information System (INIS)

    Delin, A.

    2002-06-01

    Relativistic all-electron full-potential first-principles calculations have been performed in order to study the symmetry of the energy levels around the valence band maximum in the zinc blende II-VI semiconductors β-HgS, HgSe, and HgTe. It is demonstrated that in general, an inverted band-structure does not necessarily lead to a zero fundamental energy gap for systems with zinc blende symmetry. Specifically, β-HgS is found to have at the same time an inverted band structure, and a small, slightly indirect, fundamental energy gap. Possibly, the energy levels around the valence band maximum order differently in each of these systems. (author)

  8. Environmental Effects on the Metallicities of Early-Type Galaxies

    Science.gov (United States)

    Jones, Christine; Oliversen, Ronald (Technical Monitor)

    2004-01-01

    We completed and published two papers in the Astrophysical Journal based on research from grant. In the first paper we analyzed nine X-ray-bright Virgo early-type galaxies observed by both ASCA and ROSAT. Through spatially resolved spectroscopy, we determined the radial temperature profiles and abundances of Mg, Si, and Fe for six galaxies. The temperature profiles are consistent with isothermal temperatures outside of cooler regions at the galaxies' centers. We present new evidence for iron abundance gradients in NGC 4472 and NGC 4649 and confirm the previous results on NGC 4636. Mg and Si abundance gradients on average are flatter than those of iron and correspond to an underabundance of α-process elements at high Fe values, while at low iron the element ratios favor enrichment by Type II supernovae (SNe). We explain the observed trend using the metallicity dependence of SN Ia metal production and present constraints on the available theoretical modeling for low-metallicity inhibition of SNe Ia. In the second paper We analyzed nine X-ray-bright Virgo early-type galaxies observed by both ASCA and ROSAT. Through spatially resolved spectroscopy, we determined the radial temperature profiles and abundances of Mg, Si, and Fe for six galaxies. The temperature profiles are consistent with isothermal temperatures outside of cooler regions at the galaxies' centers. We present new evidence for iron abundance gradients in NGC 4472 and NGC 4649 and confirm the previous results on NGC 4636. Mg and Si abundance gradients on average are flatter than those of iron and correspond to an underabundance of α-process elements at high Fe values, while at low iron the element ratios favor enrichment by Type I1 supernovae (SNe). We explain the observed trend using the metallicity dependence of SN Ia metal production and present constraints on the available theoretical modeling for low-metallicity inhibition of SNe Ia.

  9. Biologically active new Fe(II, Co(II, Ni(II, Cu(II, Zn(II and Cd(II complexes of N-(2-thienylmethylenemethanamine

    Directory of Open Access Journals (Sweden)

    C. SPÎNU

    2008-04-01

    Full Text Available Iron(II, cobalt(II, nickel (II, copper (II, zinc(II and cadmium(II complexes of the type ML2Cl2, where M is a metal and L is the Schiff base N-(2-thienylmethylenemethanamine (TNAM formed by the condensation of 2-thiophenecarboxaldehyde and methylamine, were prepared and characterized by elemental analysis as well as magnetic and spectroscopic measurements. The elemental analyses suggest the stoichiometry to be 1:2 (metal:ligand. Magnetic susceptibility data coupled with electronic, ESR and Mössbauer spectra suggest a distorted octahedral structure for the Fe(II, Co(II and Ni(II complexes, a square-planar geometry for the Cu(II compound and a tetrahedral geometry for the Zn(II and Cd(II complexes. The infrared and NMR spectra of the complexes agree with co-ordination to the central metal atom through nitrogen and sulphur atoms. Conductance measurements suggest the non-electrolytic nature of the complexes, except for the Cu(II, Zn(II and Cd(II complexes, which are 1:2 electrolytes. The Schiff base and its metal chelates were screened for their biological activity against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and the metal chelates were found to possess better antibacterial activity than that of the uncomplexed Schiff base.

  10. Characterization of the Unusual Product from the Reaction between Cobalt(II) Chloride, Ethane-1,2-diamine, and Hydrochloric Acid: An Undergraduate Project Involving an Unknown Metal Complex.

    Science.gov (United States)

    Curtis, Neil F.; And Others

    1986-01-01

    Discusses the need for student research-type chemistry projects based upon "unknown" metal complexes. Describes an experiment involving the product from the reaction between cobalt(II) chloride, ethane-1,2-diamine (en) and concentrated hydrochloric acid. Outlines the preparation of the cobalt complex, along with procedure, results and…

  11. RED SUPERGIANTS AS COSMIC ABUNDANCE PROBES: THE FIRST DIRECT METALLICITY DETERMINATION OF NGC 4038 IN THE ANTENNAE

    International Nuclear Information System (INIS)

    Lardo, C.; Davies, B.; Kudritzki, R-P.; Gazak, J. Z.; Evans, C. J.; Patrick, L. R.; Bergemann, M.; Plez, B.

    2015-01-01

    We present a direct determination of the stellar metallicity in the close pair galaxy NGC 4038 (D = 20 Mpc) based on the quantitative analysis of moderate-resolution KMOS/Very Large Telescope spectra of three super star clusters. The method adopted in our analysis has been developed and optimized to measure accurate metallicities from atomic lines in the J-band of single red supergiant (RSG) or RSG-dominated star clusters. Hence, our metallicity measurements are not affected by the biases and poorly understood systematics inherent to strong line H ii methods, which are routinely applied to massive data sets of galaxies. We find [Z] = +0.07 ± 0.03 and compare our measurements to H ii strong line calibrations. Our abundances and literature data suggest the presence of a flat metallicity gradient, which can be explained as redistribution of metal-rich gas following the strong interaction

  12. Caracterización de escorias metalúrgicas procedentes de yacimientos arqueológicos de Navarra (Siglos II a.C.- IV d.C.

    Directory of Open Access Journals (Sweden)

    Ros-Latienda, L.

    2013-12-01

    Full Text Available The Archaeology Section of the Government of Navarre put forward a proposal to undertake research in the characterization of a set of pieces from 2nd century B.C. to 4th century A.D. retrieved from excavations in different archaeological sites in this province, to obtain data related to the manufacturing process of the investigated artefacts and to compare the level of technical skills in different times and places, so as to achieve a better understanding of technological abilities and material culture. The finds discussed in this paper are of interest from an archaeometallurgical point of view, and they consist mainly of metallurgical slags, remains of manufactured pieces, and minerals residues used to obtain various metals. In addition to carrying out their chemical analyses by inductively coupled plasma (ICP, the study of six samples was performed by optical and scanning electron microscopy and energy-dispersive X-ray microanalysis (EDX which revealed the composition of large areas of the slags, and the study was finally completed by the determination of the phases present by X rays diffraction.Desde la Sección de Arqueología del Gobierno de Navarra llegó la propuesta de caracterizar una serie de piezas comprendidas entre el siglo II a.C. y el siglo IV d.C. procedentes de yacimientos arqueológicos de esta provincia con objeto de obtener datos relacionados con la tecnología que las produjo y poder comparar el grado de desarrollo técnico de diferentes épocas y lugares. Interesaba el estudio de estas piezas desde el punto de vista metalúrgico, habiendo entre ellas mayoritariamente escorias metalúrgicas, restos de piezas fabricadas y restos minerales utilizados en la obtención de diversos metales. Además de proceder a su análisis químico mediante técnica de plasma acoplado inductivamente (ICP, se estudiaron seis muestras mediante microscopía óptica, electrónica de barrido y microanálisis por energía dispersiva de rayos X (EDAX

  13. Uniform gradient expansions

    CERN Document Server

    Giovannini, Massimo

    2015-01-01

    Cosmological singularities are often discussed by means of a gradient expansion that can also describe, during a quasi-de Sitter phase, the progressive suppression of curvature inhomogeneities. While the inflationary event horizon is being formed the two mentioned regimes coexist and a uniform expansion can be conceived and applied to the evolution of spatial gradients across the protoinflationary boundary. It is argued that conventional arguments addressing the preinflationary initial conditions are necessary but generally not sufficient to guarantee a homogeneous onset of the conventional inflationary stage.

  14. High gradient superconducting quadrupoles

    International Nuclear Information System (INIS)

    Lundy, R.A.; Brown, B.C.; Carson, J.A.; Fisk, H.E.; Hanft, R.H.; Mantsch, P.M.; McInturff, A.D.; Remsbottom, R.H.

    1987-07-01

    Prototype superconducting quadrupoles with a 5 cm aperture and gradient of 16 kG/cm have been built and tested as candidate magnets for the final focus at SLC. The magnets are made from NbTi Tevatron style cable with 10 inner and 14 outer turns per quadrant. Quench performance and multipole data are presented. Design and data for a low current, high gradient quadrupole, similar in cross section but wound with a cable consisting of five insulated conductors are also discussed

  15. Coordination chemistry of two heavy metals: I, Ligand preferences in lead(II) complexation, toward the development of therapeutic agents for lead poisoning: II, Plutonium solubility and speciation relevant to the environment

    Energy Technology Data Exchange (ETDEWEB)

    Neu, Mary Patricia [Univ. of California, Berkeley, CA (United States)

    1993-11-01

    The coordination chemistry and solution behavior of the toxic ions lead(II) and plutonium(IV, V, VI) have been investigated. The ligand pKas and ligand-lead(II) stability constants of one hydroxamic acid and four thiohydroaxamic acids were determined. Solution thermodynamic results indicate that thiohydroxamic acids are more acidic and slightly better lead chelators than hydroxamates, e.g., N-methylthioaceto-hydroxamic acid, pKa = 5.94, logβ120 = 10.92; acetohydroxamic acid, pKa = 9.34, logβ120 = 9.52. The syntheses of lead complexes of two bulky hydroxamate ligands are presented. The X-ray crystal structures show the lead hydroxamates are di-bridged dimers with irregular five-coordinate geometry about the metal atom and a stereochemically active lone pair of electrons. Molecular orbital calculations of a lead hydroxamate and a highly symmetric pseudo octahedral lead complex were performed. The thermodynamic stability of plutonium(IV) complexes of the siderophore, desferrioxamine B (DFO), and two octadentate derivatives of DFO were investigated using competition spectrophotometric titrations. The stability constant measured for the plutonium(IV) complex of DFO-methylterephthalamide is logβ120 = 41.7. The solubility limited speciation of 242Pu as a function of time in near neutral carbonate solution was measured. Individual solutions of plutonium in a single oxidation state were added to individual solutions at pH = 6.0, T = 30.0, 1.93 mM dissolved carbonate, and sampled over intervals up to 150 days. Plutonium solubility was measured, and speciation was investigated using laser photoacoustic spectroscopy and chemical methods.

  16. Coordination chemistry of two heavy metals: I, Ligand preferences in lead(II) complexation, toward the development of therapeutic agents for lead poisoning: II, Plutonium solubility and speciation relevant to the environment

    International Nuclear Information System (INIS)

    Neu, M.P.

    1993-11-01

    The coordination chemistry and solution behavior of the toxic ions lead(II) and plutonium(IV, V, VI) have been investigated. The ligand pK a s and ligand-lead(II) stability constants of one hydroxamic acid and four thiohydroaxamic acids were determined. Solution thermodynamic results indicate that thiohydroxamic acids are more acidic and slightly better lead chelators than hydroxamates, e.g., N-methylthioaceto-hydroxamic acid, pK a = 5.94, logβ 120 = 10.92; acetohydroxamic acid, pK a = 9.34, logβ l20 = 9.52. The syntheses of lead complexes of two bulky hydroxamate ligands are presented. The X-ray crystal structures show the lead hydroxamates are di-bridged dimers with irregular five-coordinate geometry about the metal atom and a stereochemically active lone pair of electrons. Molecular orbital calculations of a lead hydroxamate and a highly symmetric pseudo octahedral lead complex were performed. The thermodynamic stability of plutonium(IV) complexes of the siderophore, desferrioxamine B (DFO), and two octadentate derivatives of DFO were investigated using competition spectrophotometric titrations. The stability constant measured for the plutonium(IV) complex of DFO-methylterephthalamide is logβ 110 = 41.7. The solubility limited speciation of 242 Pu as a function of time in near neutral carbonate solution was measured. Individual solutions of plutonium in a single oxidation state were added to individual solutions at pH = 6.0, T = 30.0, 1.93 mM dissolved carbonate, and sampled over intervals up to 150 days. Plutonium solubility was measured, and speciation was investigated using laser photoacoustic spectroscopy and chemical methods

  17. Potentiometric titration for determining the composition and stability of metal(II) alginates and pectinates in aqueous solutions

    Science.gov (United States)

    Kaisheva, N. Sh.; Kaishev, A. Sh.

    2015-07-01

    The compositions and stabilities of Cu2+, Mn2+, Pb2+, Ca2+, Zn2+, Cd2+, Co2+, and Ni2+ alginates and pectinates are determined in aqueous solutions via titrimetry and potentiometry with calculations performed using Bjerrum's method, the curve intersection technique, and the equilibrium shift method. It is found that the interaction between Cu2+ and polyuronides is a stepwise process and, depending on the ligand concentration and the method of determination, Cu2+ alginate can be characterized by its ML, ML2, and ML3 compositions (where M is the metal ion and L is the structural unit of polyuronide) and stability constants logβ = 2.65, 5.00-5.70, and 7.18-7.80, respectively. The compositions of Cu2+ pectinates are ML and ML2 with logβ = 3.00 and 7.64-7.94, respectively. It is concluded that Pb2+, Ca2+, Mn2+, Zn2+, Cd2+, Co2+, and Ni2+ ions form only alginates and pectinates of ML2 composition with logβ values of 3.45 (Pb2+ alginate), 2.20 (Ca2+ alginate), 1.06 (Mn2+ alginate), 3.51 (Pb2+ pectinate), 2.35 (Ca2+ pectinate), and 1.24 (Mn2+ pectinate). The pectinates are shown to be more stable than the alginates, the most stable compounds being those formed by polyuronides and Cu2+. The least stable are those with Mn2+.

  18. Origin of the Strong Interaction between Polar Molecules and Copper(II) Paddle-Wheels in Metal Organic Frameworks.

    Science.gov (United States)

    Ongari, Daniele; Tiana, Davide; Stoneburner, Samuel J; Gagliardi, Laura; Smit, Berend

    2017-07-20

    The copper paddle-wheel is the building unit of many metal organic frameworks. Because of the ability of the copper cations to attract polar molecules, copper paddle-wheels are promising for carbon dioxide adsorption and separation. They have therefore been studied extensively, both experimentally and computationally. In this work we investigate the copper-CO 2 interaction in HKUST-1 and in two different cluster models of HKUST-1: monocopper Cu(formate) 2 and dicopper Cu 2 (formate) 4 . We show that density functional theory methods severely underestimate the interaction energy between copper paddle-wheels and CO 2 , even including corrections for the dispersion forces. In contrast, a multireference wave function followed by perturbation theory to second order using the CASPT2 method correctly describes this interaction. The restricted open-shell Møller-Plesset 2 method (ROS-MP2, equivalent to (2,2) CASPT2) was also found to be adequate in describing the system and used to develop a novel force field. Our parametrization is able to predict the experimental CO 2 adsorption isotherms in HKUST-1, and it is shown to be transferable to other copper paddle-wheel systems.

  19. Static Equilibrium Configurations of Charged Metallic Bodies

    African Journals Online (AJOL)

    Key words: Static equilibrium, charged metallic body, potential energy, projected gradient method. ... television, radio, internet, microwave ovens, mobile telephones, satellite communication systems, radar systems, electrical motors, electrical.

  20. Manipulating the Gradient

    Science.gov (United States)

    Gaze, Eric C.

    2005-01-01

    We introduce a cooperative learning, group lab for a Calculus III course to facilitate comprehension of the gradient vector and directional derivative concepts. The lab is a hands-on experience allowing students to manipulate a tangent plane and empirically measure the effect of partial derivatives on the direction of optimal ascent. (Contains 7…

  1. Random cyclic stress-strain responses of a stainless steel pipe-weld metal. II. A modeling

    International Nuclear Information System (INIS)

    Zhao, Y.X.; Wang, J.N.

    2000-01-01

    For pt.I see ibid., vol.199, p.303-14, 2000. This paper pays special attention to an issue that there is a significant scatter of the stress-strain responses of a nuclear engineering material, 1Cr18Ni9Ti stainless steel pipe-weld metal. Efforts are made to reveal the random fatigue damage character by fracture surface observations and to model the random responses by introducing probability-based stress-strain curves of Ramberg-Osgood relation and its modified form. Results reveal that the fatigue damage is subjected to, 3-D interacting and involved microcracks. The three stages, namely microstructural short cracks (MSC), physical short cracks (PSC) and long cracks (LC) subdivided by Miller and de los Rios, can give a good characterization of the damage process. Both micro- and macro-behaviour of the material have the character of three stages. The 3-D effects are strong in the MSC stage, tend to a gradual decrease in the PSC stage, and then show saturation after going to the LC stage. Intrinsic causes of the random behaviour are the difference and evolution of the microstructural conditions ahead of the dominant crack tips. The 'effectively short fatigue crack criterion' introduced by Zhao et al. in observing the material surface short crack behaviour could facilitate an understanding of the mechanism of interaction and evolution. Based on the previous obtained appropriate assumed distribution, normal model, for the cyclic stress amplitude, the probability-based curves are approximated by the mean value and standard deviation cyclic stress-strain curves. Then, fatigue analysis at arbitrarily given reliability can be conveniently made according to the normal distribution function. To estimate these curves, a maximum likelihood method is developed. The analysis reveals that the curves could give a good modeling of the random responses of material. (orig.)

  2. Interactions of nickel(II) with histones. Stability and solution structure of complexes with CH3CO-Cys-Ala-Ile-His-NH2, a putative metal binding sequence of histone H3.

    Science.gov (United States)

    Bal, W; Lukszo, J; Jezowska-Bojczuk, M; Kasprzak, K S

    1995-01-01

    Nickel(II) compounds are established human carcinogens, but the molecular mechanisms underlying their activity are only partially known. One mechanism may include mediation by nickel of promutagenic oxidative DNA damage that depends on Ni(II) binding to chromatin. To characterize such binding at the histone moiety of chromatin, we synthesized the peptide CH3CO-Cys-Ala-Ile-His-NH2 (L), a model of the evolutionarily conserved motif in histone H3 with expected affinity for transition metals, and evaluated its reactivity toward Ni(II). Combined spectroscopic (UV/vis, CD, NMR) and potentiometric measurements showed that, at physiological pH, mixtures of Ni(II) and L yielded unusual macrochelate complexes, NiL and NiL2, in which the metal cation was bound through Cys and His side chains in a square-planar arrangement. Above pH 9, a NiH-3L complex was formed, structurally analogous to typical square-planar nickel complexes. These complexes are expected to catalyze oxidation reactions, and therefore, coordination of Ni(II) by the L motif in core histone H3 may be a key event in oxidative DNA base damage observed in the process of Ni(II)-induced carcinogenesis.

  3. Metallic complexes with glyphosate: a review

    OpenAIRE

    Coutinho, Cláudia F. B.; Mazo, Luiz Henrique

    2005-01-01

    We present studies involving metallic ions and the herbicide glyphosate. The metallic complexes of Cu(II), Zn(II), Mn(II), Ni(II), Cd(II), Pb(II), Cr(III), Fe(III), Co(III), ammonium, sodium, Ag(I), alkaline earth metals and of some lanthanides ions are described. The complexes are discussed in terms of their synthesis, identification, stability and structural properties, based on data from the current literature.

  4. Metallic complexes with glyphosate: a review

    International Nuclear Information System (INIS)

    Coutinho, Claudia F.B.; Mazo, Luiz Henrique

    2005-01-01

    We present studies involving metallic ions and the herbicide glyphosate. The metallic complexes of Cu(II), Zn(II), Mn(II), Ni(II), Cd(II), Pb(II), Cr(III), Fe(III), Co(III), ammonium, sodium, Ag(I), alkaline earth metals and of some lanthanides ions are described. The complexes are discussed in terms of their synthesis, identification, stability and structural properties, based on data from the current literature. (author)

  5. Bigravity from gradient expansion

    International Nuclear Information System (INIS)

    Yamashita, Yasuho; Tanaka, Takahiro

    2016-01-01

    We discuss how the ghost-free bigravity coupled with a single scalar field can be derived from a braneworld setup. We consider DGP two-brane model without radion stabilization. The bulk configuration is solved for given boundary metrics, and it is substituted back into the action to obtain the effective four-dimensional action. In order to obtain the ghost-free bigravity, we consider the gradient expansion in which the brane separation is supposed to be sufficiently small so that two boundary metrics are almost identical. The obtained effective theory is shown to be ghost free as expected, however, the interaction between two gravitons takes the Fierz-Pauli form at the leading order of the gradient expansion, even though we do not use the approximation of linear perturbation. We also find that the radion remains as a scalar field in the four-dimensional effective theory, but its coupling to the metrics is non-trivial.

  6. Synthesis, Characterization, Crystal Structure and Antibacterial Activities of Transition Metal(II Complexes of the Schiff Base 2-[(4-Methylphenyliminomethyl]-6-methoxyphenol

    Directory of Open Access Journals (Sweden)

    Guo-Liang Zhao

    2009-05-01

    Full Text Available Five transition metal(II complexes, [ML2Cl2] 1~5, were synthesized from the reaction of MCl2·nH2O (M = Mn, Co, Ni, Cu, Cd and the Schiff base ligand 2-[(4-methylphenyliminomethyl]-6-methoxyphenol (C15H15NO2, L, obtained by condensation of o-vanillin (2-hydroxy-3-methoxybenzaldehyde with p-toluidine. They were characterized by elemental analysis, molar conductance, FT-IR spectra, thermal analysis. The structure of complex 1 was determined by single-crystal X-ray diffraction. Its crystal structure is of monoclinic system, space group P21/c with a = 9.0111(18 Å, b = 11.222(2 Å, c =28.130 (6 Å, α = 90 º, β = 92.29(3 º, γ = 90 º, V = 2867.6(10 Å3, Z = 4. The Mn atom is six-coordinate and displays distorted octahedral geometry.The Schiff base ligand and its complexes have been tested in vitro to evaluate their antibacterial activity against bacteria, viz., Escherichia coli, Staphylococcus aureus and Bacillus subtilis. It has been found that the complexes have higher activity than the corresponding free Schiff base ligand against the same bacteria.

  7. Growth of PbTe nanorods controlled by polymerized tellurium anions and metal(II) amides via composite-hydroxide-mediated approach

    Energy Technology Data Exchange (ETDEWEB)

    Wan Buyong [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); College of Physics and Information Technology, Chongqing Normal University, Chongqing 400047 (China); Hu Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Liu Hong [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Xiong Yufeng [National Center for Nanoscience and Technology, Beijing 100080 (China); Li Feiyun; Xi Yi; He Xiaoshan [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)

    2009-09-15

    The pure face-centered-cubic PbTe nanorods have been synthesized by the composite-hydroxide-mediated approach using hydrazine as a reducing agent. The method is based on reaction among reactants in the melts of potassium hydroxide and sodium hydroxide eutectic at 170-220 deg. C and normal atmosphere without using any organic dispersant or surface-capping agent. Scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy were used to characterize the structure, morphology and composition of the samples. The diameters of nanorods are almost fixed, while the lengths can be tunable under different growth time and temperatures. The growth mechanism of PbTe nanorods is investigated via UV-vis absorption, demonstrating that polymerized tellurium anions and metal(II) amides in the hydrazine hydroxide melts could control the crystallization and growth process of PbTe nanostructures. The band gap of as-synthesized PbTe nanorods has been calculated based on UV-vis-NIR optical diffuse reflectance spectra data.

  8. Growth of PbTe nanorods controlled by polymerized tellurium anions and metal(II) amides via composite-hydroxide-mediated approach

    International Nuclear Information System (INIS)

    Wan Buyong; Hu Chenguo; Liu Hong; Xiong Yufeng; Li Feiyun; Xi Yi; He Xiaoshan

    2009-01-01

    The pure face-centered-cubic PbTe nanorods have been synthesized by the composite-hydroxide-mediated approach using hydrazine as a reducing agent. The method is based on reaction among reactants in the melts of potassium hydroxide and sodium hydroxide eutectic at 170-220 deg. C and normal atmosphere without using any organic dispersant or surface-capping agent. Scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy were used to characterize the structure, morphology and composition of the samples. The diameters of nanorods are almost fixed, while the lengths can be tunable under different growth time and temperatures. The growth mechanism of PbTe nanorods is investigated via UV-vis absorption, demonstrating that polymerized tellurium anions and metal(II) amides in the hydrazine hydroxide melts could control the crystallization and growth process of PbTe nanostructures. The band gap of as-synthesized PbTe nanorods has been calculated based on UV-vis-NIR optical diffuse reflectance spectra data.

  9. Gradient-Index Optics

    Science.gov (United States)

    2010-03-31

    nonimaging design capabilities to incorporate 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 12-04-2011 13. SUPPLEMENTARY NOTES The views, opinions...Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS Imaging Optics, Nonimaging Optics, Gradient Index Optics, Camera, Concentrator...imaging and nonimaging design capabilities to incorporate manufacturable GRIN lenses can provide imaging lens systems that are compact and

  10. Migration of trace heavy metals at the sea water/sediment interface

    International Nuclear Information System (INIS)

    Terada, Kikuo; Tomiyama, Chisato

    1984-01-01

    Migration behavior of some trace heavy metals such as Co(II), Cu(II), Mn(II) and Zn(II) at the sea water/sediment interface was investigated by tank experiments. The sea water which was doped with these metal ions (ppb to ppm levels) allowed to contact with the raw-, ignited- and autoclaved-marine sediments and the change of the concentration of each metal was traced at definite time intervals. At the end of the experiments, a core sample of the sediment was taken and analyzed for each metal in every 1 mm thick segment. On the other hand, the surface sediment was submitted to partial extraction with various kinds of reagents to estimate the chemical species of the metals captured in the sediment. While every metal ion was quickly adsorbed on surface of the raw sediment, a concentration gradient from surface to bottom of the water phase occurred in the ignited sediment system. The migration of manganese to the sediment phase was assumed to be concerned with bacterial activity in the sediment. Copper and zinc seemed to be adsorbed very quickly onto some fine sediment particles by the formation of organometallic complexes with some organic materials existing in the sediments. Cobalt migrated relatively fast downward within the sediment phase after its deposition. (author)

  11. Metal components analysis of metallothionein-III in the brain sections of metallothionein-I and metallothionein-II null mice exposed to mercury vapor with HPLC/ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Kameo, Satomi; Nakai, Kunihiko; Kurokawa, Naoyuki; Satoh, Hiroshi [Tohoku University, Graduate School of Medicine, Aoba-ku, Sendai (Japan); Kanehisa, Tomokazu; Naganuma, Akira [Tohoku University, Graduate School of Pharmaceutical Sciences, Sendai (Japan)

    2005-04-01

    Mercury vapor is effectively absorbed via inhalation and easily passes through the blood-brain barrier; therefore, mercury poisoning with primarily central nervous system symptoms occurs. Metallothionein (MT) is a cysteine-rich metal-binding protein and plays a protective role in heavy-metal poisoning and it is associated with the metabolism of trace elements. Two MT isoforms, MT-I and MT-II, are expressed coordinately in all mammalian tissues, whereas MT-III is a brain-specific member of the MT family. MT-III binds zinc and copper physiologically and is seemed to have important neurophysiological and neuromodulatory functions. The MT functions and metal components of MTs in the brain after mercury vapor exposure are of much interest; however, until now they have not been fully examined. In this study, the influences of the lack of MT-I and MT-II on mercury accumulation in the brain and the changes of zinc and copper concentrations and metal components of MTs were examined after mercury vapor exposure by using MT-I, II null mice and 129/Sv (wild-type) mice as experimental animals. MT-I, II null mice and wild-type mice were exposed to mercury vapor or an air stream for 2 h and were killed 24 h later. The brain was dissected into the cerebral cortex, the cerebellum, and the hippocampus. The concentrations of mercury in each brain section were determined by cold vapor atomic absorption spectrometry. The concentrations of mercury, copper, and zinc in each brain section were determined by inductively coupled plasma mass spectrometry (ICP-MS). The mercury accumulated in brains after mercury vapor exposure for MT-I, II null mice and wild-type mice. The mercury levels of MT-I, II null mice in each brain section were significantly higher than those of wild-type mice after mercury vapor exposure. A significant change of zinc concentrations with the following mercury vapor exposure for MT-I, II null mice was observed only in the cerebellum analyzed by two-way analysis of

  12. pH-specific hydrothermal assembly of binary and ternary Pb(II)-(O,N-carboxylic acid) metal organic framework compounds: correlation of aqueous solution speciation with variable dimensionality solid-state lattice architecture and spectroscopic signatures.

    Science.gov (United States)

    Gabriel, C; Perikli, M; Raptopoulou, C P; Terzis, A; Psycharis, V; Mateescu, C; Jakusch, T; Kiss, T; Bertmer, M; Salifoglou, A

    2012-09-03

    Hydrothermal pH-specific reactivity in the binary/ternary systems of Pb(II) with the carboxylic acids N-hydroxyethyl-iminodiacetic acid (Heida), 1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid (Dpot), and 1,10-phenanthroline (Phen) afforded the new well-defined crystalline compounds [Pb(Heida)](n)·nH(2)O(1), [Pb(Phen)(Heida)]·4H(2)O(2), and [Pb(3)(NO(3))(Dpot)](n)(3). All compounds were characterized by elemental analysis, FT-IR, solution or/and solid-state NMR, and single-crystal X-ray diffraction. The structures in 1-2 reveal the presence of a Pb(II) center coordinated to one Heida ligand, with 1 exhibiting a two-dimensional (2D) lattice extending to a three-dimensional (3D) one through H-bonding interactions. The concurrent aqueous speciation study of the binary Pb(II)-Heida system projects species complementing the synthetic efforts, thereby lending credence to a global structural speciation strategy in investigating binary/ternary Pb(II)-Heida/Phen systems. The involvement of Phen in 2 projects the significance of nature and reactivity potential of N-aromatic chelators, disrupting the binary lattice in 1 and influencing the nature of the ultimately arising ternary 3D lattice. 3 is a ternary coordination polymer, where Pb(II)-Dpot coordination leads to a 2D metal-organic-framework material with unique architecture. The collective physicochemical properties of 1-3 formulate the salient features of variable dimensionality metal-organic-framework lattices in binary/ternary Pb(II)-(hydroxy-carboxylate) structures, based on which new Pb(II) materials with distinct architecture and spectroscopic signature can be rationally designed and pursued synthetically.

  13. Adsorption and separation of CO{sub 2} on Fe(II)-MOF-74: Effect of the open metal coordination site

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Wolong; Yang, Jiangfeng; Li, Libo; Li, Jinping, E-mail: Jpli211@hotmail.com

    2014-05-01

    We describe the successful synthesis of Fe{sub 2}(dobdc) (dobdc{sup 4−}=2, 5-dioxido-1, 4-benzenedicarboxylate), which has an open metal coordination site Fe(II), and investigate the adsorption properties of three important molecules CO{sub 2}, CH{sub 4} and N{sub 2} on Fe{sub 2}(dobdc) and an oxidized analog, Fe{sub 2}(O{sub 2})(dobdc). We found that CO{sub 2} adsorption isotherm of Fe{sub 2}(dobdc) at 10 bar was very different from Fe{sub 2}(O{sub 2})(dobdc), with the capacities of 144.5 cm{sup 3} g{sup −1} and 98.1 cm{sup 3} g{sup −1}, respectively. The adsorption capacities for CH{sub 4} were 75.8 cm{sup 3} g{sup −1} and 36.8 cm{sup 3} g{sup −1}, respectively, at 10 bar in these materials. Using ideal adsorbed solution theory (IAST), we obtain the adsorption selectivity for CO{sub 2} using equimolar mixtures of CO{sub 2}/CH{sub 4} and CO{sub 2}/N{sub 2} with Fe{sub 2}(dobdc) and Fe{sub 2}(O{sub 2})(dobdc) as a function of pressure. Fe{sub 2}(dobdc) has a higher, more stable separation factor. - Graphical abstract: The selectivity of CO{sub 2}/CH{sub 4} mixture (50%/50%) on Fe{sub 2}(dobdc) and Fe{sub 2}(O{sub 2})(dobdc). - Highlights: • We explored the contrastive adsorption of CO{sub 2}, CH{sub 4}, and N{sub 2} in Fe{sub 2}(dobdc) and Fe{sub 2}(O{sub 2})(dobdc) for the first time. • Through IAST, we obtain the adsorption selectivity for CO{sub 2} from the equimolar mixture of CO{sub 2}/CH{sub 4} and CO{sub 2}/N{sub 2} for Fe{sub 2}(dobdc) and Fe{sub 2}(O{sub 2})(dobdc). • We determined that the open coordination site of Fe(II) is the main reason for different adsorption performances.

  14. Designing optimal nanofocusing with a gradient hyperlens

    Directory of Open Access Journals (Sweden)

    Shen Lian

    2017-11-01

    Full Text Available We report the design of a high-throughput gradient hyperbolic lenslet built with real-life materials and capable of focusing a beam into a deep sub-wavelength spot of λ/23. This efficient design is achieved through high-order transformation optics and circular effective-medium theory (CEMT, which are used to engineer the radially varying anisotropic artificial material based on the thin alternating cylindrical metal and dielectric layers. The radial gradient of the effective anisotropic optical constants allows for matching the impedances at the input and output interfaces, drastically improving the throughput of the lenslet. However, it is the use of the zeroth-order CEMT that enables the practical realization of a gradient hyperlens with realistic materials. To illustrate the importance of using the CEMT versus the conventional planar effective-medium theory (PEMT for cylindrical anisotropic systems, such as our hyperlens, both the CEMT and PEMT are adopted to design gradient hyperlenses with the same materials and order of elemental layers. The CEMT- and PEMT-based designs show similar performance if the number of metal-dielectric binary layers is sufficiently large (9+ pairs and if the layers are sufficiently thin. However, for the manufacturable lenses with realistic numbers of layers (e.g. five pairs and thicknesses, the performance of the CEMT design continues to be practical, whereas the PEMT-based design stops working altogether. The accurate design of transformation optics-based layered cylindrical devices enabled by CEMT allow for a new class of robustly manufacturable nanophotonic systems, even with relatively thick layers of real-life materials.

  15. Ni(II

    African Journals Online (AJOL)

    Preferred Customer

    analytical chemistry, catalysis, electrochemistry, ring-opening metathesis ... Ethanol was dried over anhydrous copper(II) sulfate and distilled over metallic sodium. ... All bacteria were inoculated into Nutrient Broth (Difco) and incubated for 24 h ...

  16. Canonical trivialization of gravitational gradients

    International Nuclear Information System (INIS)

    Niedermaier, Max

    2017-01-01

    A one-parameter family of canonical transformations is constructed that reduces the Hamiltonian form of the Einstein–Hilbert action to its strong coupling limit where dynamical spatial gradients are absent. The parameter can alternatively be viewed as the overall scale of the spatial metric or as a fractional inverse power of Newton’s constant. The generating function of the canonical transformation is constructed iteratively as a powerseries in the parameter to all orders. The algorithm draws on Lie–Deprit transformation theory and defines a ‘trivialization map’ with several bonus properties: (i) Trivialization of the Hamiltonian constraint implies that of the action while the diffeomorphism constraint is automatically co-transformed. (ii) Only a set of ordinary differential equations needs to be solved to drive the iteration via a homological equation where no gauge fixing is required. (iii) In contrast to (the classical limit of) a Lagrangian trivialization map the algorithm also produces series solutions of the field equations. (iv) In the strong coupling theory temporal gauge variations are abelian, nevertheless the map intertwines with the respective gauge symmetries on the action, the field equations, and their solutions. (paper)

  17. Canonical trivialization of gravitational gradients

    Science.gov (United States)

    Niedermaier, Max

    2017-06-01

    A one-parameter family of canonical transformations is constructed that reduces the Hamiltonian form of the Einstein-Hilbert action to its strong coupling limit where dynamical spatial gradients are absent. The parameter can alternatively be viewed as the overall scale of the spatial metric or as a fractional inverse power of Newton’s constant. The generating function of the canonical transformation is constructed iteratively as a powerseries in the parameter to all orders. The algorithm draws on Lie-Deprit transformation theory and defines a ‘trivialization map’ with several bonus properties: (i) Trivialization of the Hamiltonian constraint implies that of the action while the diffeomorphism constraint is automatically co-transformed. (ii) Only a set of ordinary differential equations needs to be solved to drive the iteration via a homological equation where no gauge fixing is required. (iii) In contrast to (the classical limit of) a Lagrangian trivialization map the algorithm also produces series solutions of the field equations. (iv) In the strong coupling theory temporal gauge variations are abelian, nevertheless the map intertwines with the respective gauge symmetries on the action, the field equations, and their solutions.

  18. Effect of Cu(II), Cd(II) and Zn(II) on Pb(II) biosorption by algae Gelidium-derived materials.

    Science.gov (United States)

    Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2008-06-15

    Biosorption of Pb(II), Cu(II), Cd(II) and Zn(II) from binary metal solutions onto the algae Gelidium sesquipedale, an algal industrial waste and a waste-based composite material was investigated at pH 5.3, in a batch system. Binary Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II) solutions have been tested. For the same equilibrium concentrations of both metal ions (1 mmol l(-1)), approximately 66, 85 and 86% of the total uptake capacity of the biosorbents is taken by lead ions in the systems Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II), respectively. Two-metal results were fitted to a discrete and a continuous model, showing the inhibition of the primary metal biosorption by the co-cation. The model parameters suggest that Cd(II) and Zn(II) have the same decreasing effect on the Pb(II) uptake capacity. The uptake of Pb(II) was highly sensitive to the presence of Cu(II). From the discrete model it was possible to obtain the Langmuir affinity constant for Pb(II) biosorption. The presence of the co-cations decreases the apparent affinity of Pb(II). The experimental results were successfully fitted by the continuous model, at different pH values, for each biosorbent. The following sequence for the equilibrium affinity constants was found: Pb>Cu>Cd approximately Zn.

  19. Global correlation imaging of magnetic total field gradients

    International Nuclear Information System (INIS)

    Guo, Lianghui; Meng, Xiaohong; Shi, Lei

    2012-01-01

    Firstly we introduce the correlation imaging approach for the x-, y- and z-gradients of a magnetic total field anomaly for deriving the distribution of equivalent magnetic sources of the subsurface. In this approach, the subsurface space is divided into a regular grid, and then a correlation coefficient function is computed at each grid node, based on the cross-correlation between the x-gradient (or y-gradient or z-gradient) of the observed magnetic total field anomaly and the x-gradient (or y-gradient or z-gradient) of the theoretical magnetic total field anomaly due to a magnetic dipole. The resultant correlation coefficient is used to describe the probability of a magnetic dipole occurring at the node. We then define a global correlation coefficient function for comprehensively delineating the probability of an occurrence of a magnetic dipole, which takes, at each node, the maximum positive value of the corresponding correlation coefficient function of the three gradients. We finally test the approach both on synthetic data and real data from a metallic deposit area in the middle-lower reaches of the Yangtze River, China. (paper)

  20. Wetting of flat gradient surfaces.

    Science.gov (United States)

    Bormashenko, Edward

    2018-04-01

    Gradient, chemically modified, flat surfaces enable directed transport of droplets. Calculation of apparent contact angles inherent for gradient surfaces is challenging even for atomically flat ones. Wetting of gradient, flat solid surfaces is treated within the variational approach, under which the contact line is free to move along the substrate. Transversality conditions of the variational problem give rise to the generalized Young equation valid for gradient solid surfaces. The apparent (equilibrium) contact angle of a droplet, placed on a gradient surface depends on the radius of the contact line and the values of derivatives of interfacial tensions. The linear approximation of the problem is considered. It is demonstrated that the contact angle hysteresis is inevitable on gradient surfaces. Electrowetting of gradient surfaces is discussed. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. The Impact of Post-Procedural Asymmetry, Expansion, and Eccentricity of Bioresorbable Everolimus-Eluting Scaffold and Metallic Everolimus-Eluting Stent on Clinical Outcomes in the ABSORB II Trial.

    Science.gov (United States)

    Suwannasom, Pannipa; Sotomi, Yohei; Ishibashi, Yuki; Cavalcante, Rafael; Albuquerque, Felipe N; Macaya, Carlos; Ormiston, John A; Hill, Jonathan; Lang, Irene M; Egred, Mohaned; Fajadet, Jean; Lesiak, Maciej; Tijssen, Jan G; Wykrzykowska, Joanna J; de Winter, Robbert J; Chevalier, Bernard; Serruys, Patrick W; Onuma, Yoshinobu

    2016-06-27

    The study sought to investigate the relationship between post-procedural asymmetry, expansion, and eccentricity indices of metallic everolimus-eluting stent (EES) and bioresorbable vascular scaffold (BVS) and their respective impact on clinical events at 1-year follow-up. Mechanical properties of a fully BVS are inherently different from those of permanent metallic stent. The ABSORB II (A bioresorbable everolimus-eluting scaffold versus a metallic everolimus-eluting stent for ischaemic heart disease caused by de-novo native coronary artery lesions) trial compared the BVS and metallic EES in the treatment of a de novo coronary artery stenosis. Protocol-mandated intravascular ultrasound imaging was performed pre- and post-procedure in 470 patients (162 metallic EES and 308 BVS). Asymmetry index (AI) was calculated per lesion as: (1 - minimum scaffold/stent diameter/maximum scaffold/stent diameter). Expansion index and optimal scaffold/stent expansion followed the definition of the MUSIC (Multicenter Ultrasound Stenting in Coronaries) study. Eccentricity index (EI) was calculated as the ratio of minimum and maximum scaffold/stent diameter per cross section. The incidence of device-oriented composite endpoint (DoCE) was collected. Post-procedure, the metallic EES group was more symmetric and concentric than the BVS group. Only 8.0% of the BVS arm and 20.0% of the metallic EES arm achieved optimal scaffold/stent expansion (p 0.30 is an independent predictor of DoCE (hazard ratio: 3.43; 95% confidence interval: 1.08 to 10.92; p = 0.037). BVS implantation is more frequently associated with post-procedural asymmetric and eccentric morphology compared to metallic EES. Post-procedural devices asymmetry were independently associated with DoCE following percutaneous coronary intervention. However, this approach should be viewed as hypothesis generating due to low event rates. (ABSORB II Randomized Controlled Trial [ABSORB II]; NCT01425281). Copyright © 2016 American

  2. Gradient Boosting Machines, A Tutorial

    Directory of Open Access Journals (Sweden)

    Alexey eNatekin

    2013-12-01

    Full Text Available Gradient boosting machines are a family of powerful machine-learning techniques that have shown considerable success in a wide range of practical applications. They are highly customizable to the particular needs of the application, like being learned with respect to different loss functions. This article gives a tutorial introduction into the methodology of gradient boosting methods. A theoretical information is complemented with many descriptive examples and illustrations which cover all the stages of the gradient boosting model design. Considerations on handling the model complexity are discussed. A set of practical examples of gradient boosting applications are presented and comprehensively analyzed.

  3. The impact of auxins used in assisted phytoextraction of metals from the contaminated environment on the alterations caused by lead(II) ions in the organization of model lipid membranes.

    Science.gov (United States)

    Hąc-Wydro, Katarzyna; Sroka, Aleksandra; Jabłońska, Klaudia

    2016-07-01

    Auxins are successfully used to improve phytoextraction efficiency of metal ions from the contaminated environment, however, the mechanism of their activity in this field is not explained. Auxins are known to exert various biochemical alterations in the plant membranes and cells, but their activity involves also direct interactions with lipids leading to changes in membrane organization. Following the suggestion that the auxins-induced modifications in membrane properties alleviate toxic effect of metal ions in this paper we have undertaken the comparative studies on the effect of metal ions and metal ions/auxins mixtures on model membrane systems. The experiments were done on lipid monolayers differing in their composition spread on water subphase and on Pb(2+), Indole-3-acetic acid (IAA), 1-Naphthaleneacetic acid (NAA) and Pb(2+)/IAA and Pb(2+)/NAA water solutions. The analysis of the collected data suggests that metal ions and auxins can change fluidity of the lipid systems and weaken the interactions between monolayer components. This manifested in the increase of the mean area per molecule and the excess area per molecule values for the films on Pb(2+), auxins as well as Pb(2+)/auxin solutions as compared to the values on pure water subphase. However, the presence of auxin in the mixture with lead(II) ions makes the alterations induced by sole metal ions weaker. This effect was more pronounced for the membranes of a higher packing. Thus it was proposed that auxins may enhance phytoextraction of metal ions by weakening their destabilizing effect on membrane. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Gradient waveform synthesis for magnetic propulsion using MRI gradient coils

    International Nuclear Information System (INIS)

    Han, B H; Lee, S Y; Park, S

    2008-01-01

    Navigating an untethered micro device in a living subject is of great interest for both diagnostic and therapeutic applications. Magnetic propulsion of an untethered device carrying a magnetic core in it is one of the promising methods to navigate the device. MRI gradients coils are thought to be suitable for navigating the device since they are capable of magnetic propulsion in any direction while providing magnetic resonance images. For precise navigation of the device, especially in the peripheral region of the gradient coils, the concomitant gradient fields, as well as the linear gradient fields in the main magnetic field direction, should be considered in driving the gradient coils. For simple gradient coil configurations, the Maxwell coil in the z-direction and the Golay coil in the x- and y-directions, we have calculated the magnetic force fields, which are not necessarily the same as the conventional linear gradient fields of MRI. Using the calculated magnetic force fields, we have synthesized gradient waveforms to navigate the device along a desired path

  5. Denaturing gradient gel electrophoresis

    International Nuclear Information System (INIS)

    Kocherginskaya, S.A.; Cann, I.K.O.; Mackie, R.I.

    2005-01-01

    It is worthwhile considering that only some 30 species make up the bulk of the bacterial population in human faeces at any one time based on the classical cultivation-based approach. The situation in the rumen is similar. Thus, it is practical to focus on specific groups of interest within the complex community. These may be the predominant or the most active species, specific physiological groups or readily identifiable (genetic) clusters of phylogenetically related organisms. Several 16S rDNA fingerprinting techniques can be invaluable for selecting and monitoring sequences or phylogenetic groups of interest and are described below. Over the past few decades, considerable attention was focussed on the identification of pure cultures of microbes on the basis of genetic polymorphisms of DNA encoding rRNA such as ribotyping, amplified fragment length polymorphism and randomly amplified polymorphic DNA. However, many of these methods require prior cultivation and are less suitable for use in analysis of complex mixed populations although important in describing cultivated microbial diversity in molecular terms. Much less attention was given to molecular characterization of complex communities. In particular, research into diversity and community structure over time has been revolutionized by the advent of molecular fingerprinting techniques for complex communities. Denaturing or temperature gradient gel electrophoresis (DGGE/TGGE) methods have been successfully applied to the analysis of human, pig, cattle, dog and rodent intestinal populations

  6. Ion temperature gradient instability

    International Nuclear Information System (INIS)

    1989-01-01

    Anomalous ion thermal conductivity remains an open physics issue for the present generation of high temperature Tokamaks. It is generally believed to be due to Ion Temperature Gradient Instability (η i mode). However, it has been difficult, if not impossible to identify this instability and study the anomalous transport due to it, directly. Therefore the production and identification of the mode is pursued in the simpler and experimentally convenient configuration of the Columbia Linear Machine (CLM). CLM is a steady state machine which already has all the appropriate parameters, except η i . This parameter is being increased to the appropriate value of the order of 1 by 'feathering' a tungsten screen located between the plasma source and the experimental cell to flatten the density profile and appropriate redesign of heating antennas to steepen the ion temperature profile. Once the instability is produced and identified, a thorough study of the characteristics of the mode can be done via a wide range of variation of all the critical parameters: η i , parallel wavelength, etc

  7. Formation of a Thymine-Hg-II-Thymine Metal-Mediated DNA Base Pair: Proposal and Theoretical Calculation of the Reaction Pathway

    Czech Academy of Sciences Publication Activity Database

    Šebera, Jakub; Burda, J.; Straka, Michal; Ono, A.; Kojima, C.; Tanaka, Y.; Sychrovský, Vladimír

    2013-01-01

    Roč. 19, č. 30 (2013), s. 9884-9894 ISSN 0947-6539 R&D Projects: GA ČR GAP205/10/0228; GA MŠk(CZ) LH11033 Institutional support: RVO:61388963 Keywords : DNA structures * mercury * metalation * metal-DNA binding * nucleobases Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.696, year: 2013

  8. On the anomalous skin effect in metals. II. Some aspects of superconductors, sum-rule applications and limits of this technique

    Energy Technology Data Exchange (ETDEWEB)

    Drangeid, K E; Sommerhalder, R [IBM Research Lab., Zurich (Switzerland)

    1976-03-02

    Based on previous work applying to normal conducting metals, an analog network model for superconducting metals is developed. The reciprocal surface impendance associated with this model is used as a response function in connection with the Kramers-Kronig relations and the sum rule to compute electrodynamic properties of superconductors.

  9. Compartmentation of metals in foliage of Populus tremula grown on soils with mixed contamination. II. Zinc binding inside leaf cell organelles.

    Science.gov (United States)

    Vollenweider, Pierre; Bernasconi, Petra; Gautschi, Hans-Peter; Menard, Terry; Frey, Beat; Günthardt-Goerg, Madeleine S

    2011-01-01

    The phytoextraction potential of plants for removing heavy metals from polluted soils is determined by their capacity to store contaminants in aboveground organs and complex them safely. In this study, the metal compartmentation, elemental composition of zinc deposits and zinc complexation within leaves from poplars grown on soil with mixed metal contamination was analysed combining several histochemical and microanalytical approaches. Zinc was the only heavy metal detected and was stored in several organelles in the form of globoid deposits showing β-metachromasy. It was associated to oxygen anions and different cations, noteworthy phosphorous. The deposit structure, elemental composition and element ratios indicated that zinc was chelated by phytic acid ligands. Maturation processes in vacuolar vs. cytoplasmic deposits were suggested by differences in size and amounts of complexed zinc. Hence, zinc complexation by phytate contributed to metal detoxification and accumulation in foliage but could not prevent toxicity reactions therein. Copyright © 2010 Elsevier Ltd. All rights reserved.

  10. Compartmentation of metals in foliage of Populus tremula grown on soils with mixed contamination. II. Zinc binding inside leaf cell organelles

    Energy Technology Data Exchange (ETDEWEB)

    Vollenweider, Pierre, E-mail: pierre.vollenweider@wsl.c [Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zuercherstrasse 111, 8903 Birmensdorf (Switzerland); Bernasconi, Petra [Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zuercherstrasse 111, 8903 Birmensdorf (Switzerland); Environmental Protection Office (AfU), Aabachstrasse 5, 6300 Zug (Switzerland); Gautschi, Hans-Peter [Centre for Microscopy and Image Analysis (CMI), University of Zurich, Gloriastrasse 30, 8006 Zuerich (Switzerland); Menard, Terry; Frey, Beat; Guenthardt-Goerg, Madeleine S. [Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zuercherstrasse 111, 8903 Birmensdorf (Switzerland)

    2011-01-15

    The phytoextraction potential of plants for removing heavy metals from polluted soils is determined by their capacity to store contaminants in aboveground organs and complex them safely. In this study, the metal compartmentation, elemental composition of zinc deposits and zinc complexation within leaves from poplars grown on soil with mixed metal contamination was analysed combining several histochemical and microanalytical approaches. Zinc was the only heavy metal detected and was stored in several organelles in the form of globoid deposits showing {beta}-metachromasy. It was associated to oxygen anions and different cations, noteworthy phosphorous. The deposit structure, elemental composition and element ratios indicated that zinc was chelated by phytic acid ligands. Maturation processes in vacuolar vs. cytoplasmic deposits were suggested by differences in size and amounts of complexed zinc. Hence, zinc complexation by phytate contributed to metal detoxification and accumulation in foliage but could not prevent toxicity reactions therein. - Zinc contaminants translocated to symplast of aged leaves were detoxified by phytic acid ligands.

  11. Compartmentation of metals in foliage of Populus tremula grown on soils with mixed contamination. II. Zinc binding inside leaf cell organelles

    International Nuclear Information System (INIS)

    Vollenweider, Pierre; Bernasconi, Petra; Gautschi, Hans-Peter; Menard, Terry; Frey, Beat; Guenthardt-Goerg, Madeleine S.

    2011-01-01

    The phytoextraction potential of plants for removing heavy metals from polluted soils is determined by their capacity to store contaminants in aboveground organs and complex them safely. In this study, the metal compartmentation, elemental composition of zinc deposits and zinc complexation within leaves from poplars grown on soil with mixed metal contamination was analysed combining several histochemical and microanalytical approaches. Zinc was the only heavy metal detected and was stored in several organelles in the form of globoid deposits showing β-metachromasy. It was associated to oxygen anions and different cations, noteworthy phosphorous. The deposit structure, elemental composition and element ratios indicated that zinc was chelated by phytic acid ligands. Maturation processes in vacuolar vs. cytoplasmic deposits were suggested by differences in size and amounts of complexed zinc. Hence, zinc complexation by phytate contributed to metal detoxification and accumulation in foliage but could not prevent toxicity reactions therein. - Zinc contaminants translocated to symplast of aged leaves were detoxified by phytic acid ligands.

  12. Dissolution of metallic uranium and its alloys. Part II. Screening study results: Identification of an effective non-thermal uranium dissolution method

    International Nuclear Information System (INIS)

    Laue, C.A.; Gates-Anderson, D.; Fitch, T.E.

    2004-01-01

    Screening experiments were performed to evaluate reagent systems that deactivate pyrophoric, metallic depleted uranium waste streams at ambient temperature. The results presented led to the selection of two systems, which would be investigated further, for the design of the LLNL onsite treatment process of metallic depleted uranium wastes. The two feasible systems are: (a) 7.5 mol/l H 2 SO 4 - 1 mol/l HNO 3 and (b) 3 mol/l HCl - 1 mol/l H 3 PO 4 . The sulfuric acid system dissolves uranium metal completely, while the hydrochloric-phosphoric acid system converts the metal completely into a solid, which might be suitable for direct disposal. Both systems combine oxidation of metallic uranium with complexation of the uranium ions formed to effectively deactivate uranium.s pyrophoricity at ambient temperature. (author)

  13. Ni (II) and Cu(II) complexes of

    African Journals Online (AJOL)

    ADOWIE PERE

    ABSTRACT: The objective of this study is to investigate the antimicrobial activity of novel. Schiff base metal complexes. The resistance of micro-organisms to classical antimicrobial compounds poses a challenge to effective management and treatment of some diseases. In line with this, copper (II), nickel (II) and cobalt (II) ...

  14. Characterization of gradient control systems

    NARCIS (Netherlands)

    Cortés, Jorge; van der Schaft, Arjan; Crouch, Peter E.

    2005-01-01

    Given a general nonlinear affine control system with outputs and a torsion-free affine connection defined on its state space, we investigate the gradient realization problem: we give necessary and sufficient conditions under which the control system can be written as a gradient control system

  15. Characterization of Gradient Control Systems

    NARCIS (Netherlands)

    Cortés, Jorge; Schaft, Arjan van der; Crouch, Peter E.

    2005-01-01

    Given a general nonlinear affine control system with outputs and a torsion-free affine connection defined on its state space, we investigate the gradient realization problem: we give necessary and sufficient conditions under which the control system can be written as a gradient control system

  16. Sobolev gradients and differential equations

    CERN Document Server

    Neuberger, J W

    2010-01-01

    A Sobolev gradient of a real-valued functional on a Hilbert space is a gradient of that functional taken relative to an underlying Sobolev norm. This book shows how descent methods using such gradients allow a unified treatment of a wide variety of problems in differential equations. For discrete versions of partial differential equations, corresponding Sobolev gradients are seen to be vastly more efficient than ordinary gradients. In fact, descent methods with these gradients generally scale linearly with the number of grid points, in sharp contrast with the use of ordinary gradients. Aside from the first edition of this work, this is the only known account of Sobolev gradients in book form. Most of the applications in this book have emerged since the first edition was published some twelve years ago. What remains of the first edition has been extensively revised. There are a number of plots of results from calculations and a sample MatLab code is included for a simple problem. Those working through a fair p...

  17. Local anticorrelation between star formation rate and gas-phase metallicity in disc galaxies

    Science.gov (United States)

    Sánchez Almeida, J.; Caon, N.; Muñoz-Tuñón, C.; Filho, M.; Cerviño, M.

    2018-06-01

    Using a representative sample of 14 star-forming dwarf galaxies in the local Universe, we show the existence of a spaxel-to-spaxel anticorrelation between the index N2 ≡ log ([N II]λ 6583/H α ) and the H α flux. These two quantities are commonly employed as proxies for gas-phase metallicity and star formation rate (SFR), respectively. Thus, the observed N2 to H α relation may reflect the existence of an anticorrelation between the metallicity of the gas forming stars and the SFR it induces. Such an anticorrelation is to be expected if variable external metal-poor gas fuels the star-formation process. Alternatively, it can result from the contamination of the star-forming gas by stellar winds and SNe, provided that intense outflows drive most of the metals out of the star-forming regions. We also explore the possibility that the observed anticorrelation is due to variations in the physical conditions of the emitting gas, other than metallicity. Using alternative methods to compute metallicity, as well as previous observations of H II regions and photoionization models, we conclude that this possibility is unlikely. The radial gradient of metallicity characterizing disc galaxies does not produce the correlation either.

  18. cobalt (ii), nickel (ii)

    African Journals Online (AJOL)

    DR. AMINU

    Department of Chemistry Bayero University, P. M. B. 3011, Kano, Nigeria. E-mail: hnuhu2000@yahoo.com. ABSTRACT. The manganese (II), cobalt (II), nickel (II) and .... water and common organic solvents, but are readily soluble in acetone. The molar conductance measurement [Table 3] of the complex compounds in.

  19. The geomagnetic field gradient tensor

    DEFF Research Database (Denmark)

    Kotsiaros, Stavros; Olsen, Nils

    2012-01-01

    We develop the general mathematical basis for space magnetic gradiometry in spherical coordinates. The magnetic gradient tensor is a second rank tensor consisting of 3 × 3 = 9 spatial derivatives. Since the geomagnetic field vector B is always solenoidal (∇ · B = 0) there are only eight independent...... tensor elements. Furthermore, in current free regions the magnetic gradient tensor becomes symmetric, further reducing the number of independent elements to five. In that case B is a Laplacian potential field and the gradient tensor can be expressed in series of spherical harmonics. We present properties...... of the magnetic gradient tensor and provide explicit expressions of its elements in terms of spherical harmonics. Finally we discuss the benefit of using gradient measurements for exploring the Earth’s magnetic field from space, in particular the advantage of the various tensor elements for a better determination...

  20. Ag(I), Pb(II) and Hg(II) binding to biomolecules studied by Perturbed Angular Correlation of $\\gamma$-rays (PAC) spectroscopy: Function and toxicity of metal ions in biological systems

    CERN Multimedia

    Metal ions display diverse functions in biological systems and are essential components in both protein structure and function, and in control of biochemical reaction paths and signaling. Similarly, metal ions may be used to control structure and function of synthetic biomolecules, and thus be a tool in the design of molecules with a desired function. In this project we address a variety of questions concerning both the function of metal ions in natural systems, in synthetic biomolecules, and the toxic effect of some metal ions. All projects involve other experimental techniques such as NMR, EXAFS, UV-Vis, fluorescence, and CD spectroscopies providing complementary data, as well as interpretation of the experimental data by quantum mechanical calculations of spectroscopic properties.

  1. The removal of hydrogen sulfide from gas streams using an aqueous metal sulfate absorbent : Part II. the regeneration of copper sulfide to copper oxide - An experimental study

    NARCIS (Netherlands)

    Ter Maat, H.; Hogendoorn, J. A.; Versteeg, G. F.

    2005-01-01

    Aim of this study was to investigate the possibilities for a selective and efficient method to convert copper(II) sulfide (CuS) into copper(II) oxide (CuO). The oxidation of copper sulfide has been studied experimentally using a thermogravimetric analyzer (TGA) at temperatures ranging from 450 to

  2. Non-destructive pollution exposure assessment in the European hedgehog (Erinaceus europaeus): II. Hair and spines as indicators of endogenous metal and As concentrations

    International Nuclear Information System (INIS)

    D'Have, Helga; Scheirs, Jan; Mubiana, Valentine Kayawe; Verhagen, Ron; Blust, Ronny; Coen, Wim de

    2006-01-01

    The role of hair and spines of the European hedgehog as non-destructive monitoring tools of metal (Ag, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb, Zn) and As pollution in terrestrial ecosystems was investigated. Our results showed that mean pollution levels of a random sample of hedgehogs in Flanders are low to moderate. Yet, individual hedgehogs may be at risk for metal toxicity. Tissue distribution analyses (hair, spines, liver, kidney, muscle and fat tissue) indicated that metals and As may reach considerable concentrations in external tissues, such as hair and spines. Positive relationships were observed between concentrations in hair and those in liver, kidney and muscle for Al, Co, Cr, Cu, and Pb (0.43 < r < 0.85). Spine concentrations were positively related to liver, kidney and muscle concentrations for Cd, Co, Cr, Cu and Pb (0.37 < r < 0.62). Hair Ag, As, Fe and Zn and spine Ag, Al, As and Fe were related to metal concentrations in one or two of the investigated internal tissues (0.31 < r < 0.45). The regression models presented here may be used to predict metal and As concentrations in internal tissues of hedgehogs when concentrations in hair or spines are available. The present study demonstrated the possibility of using hair and spines for non-destructive monitoring of metal and As pollution in hedgehogs. - Hedgehog hair and spines are promising non-destructive biomonitoring tools of terrestrial metal pollution

  3. Non-destructive pollution exposure assessment in the European hedgehog (Erinaceus europaeus): II. Hair and spines as indicators of endogenous metal and As concentrations

    Energy Technology Data Exchange (ETDEWEB)

    D' Have, Helga [Ecophysiology, Biochemistry and Toxicology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)]. E-mail: helga.dhave@ua.ac.be; Scheirs, Jan [Evolutionary Biology Group, Department of Biology, University of Antwerp, B-2020 Antwerp (Belgium); Mubiana, Valentine Kayawe [Ecophysiology, Biochemistry and Toxicology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Verhagen, Ron [Evolutionary Biology Group, Department of Biology, University of Antwerp, B-2020 Antwerp (Belgium); Blust, Ronny [Ecophysiology, Biochemistry and Toxicology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Coen, Wim de [Ecophysiology, Biochemistry and Toxicology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2006-08-15

    The role of hair and spines of the European hedgehog as non-destructive monitoring tools of metal (Ag, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb, Zn) and As pollution in terrestrial ecosystems was investigated. Our results showed that mean pollution levels of a random sample of hedgehogs in Flanders are low to moderate. Yet, individual hedgehogs may be at risk for metal toxicity. Tissue distribution analyses (hair, spines, liver, kidney, muscle and fat tissue) indicated that metals and As may reach considerable concentrations in external tissues, such as hair and spines. Positive relationships were observed between concentrations in hair and those in liver, kidney and muscle for Al, Co, Cr, Cu, and Pb (0.43 < r < 0.85). Spine concentrations were positively related to liver, kidney and muscle concentrations for Cd, Co, Cr, Cu and Pb (0.37 < r < 0.62). Hair Ag, As, Fe and Zn and spine Ag, Al, As and Fe were related to metal concentrations in one or two of the investigated internal tissues (0.31 < r < 0.45). The regression models presented here may be used to predict metal and As concentrations in internal tissues of hedgehogs when concentrations in hair or spines are available. The present study demonstrated the possibility of using hair and spines for non-destructive monitoring of metal and As pollution in hedgehogs. - Hedgehog hair and spines are promising non-destructive biomonitoring tools of terrestrial metal pollution.

  4. A 2D finite element implementation of the Fleck–Willis strain-gradient flow theory

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau; Niordson, Christian Frithiof

    2013-01-01

    The lay-out of a numerical solution procedure for the strain gradient flow (rate-independent) theory by Fleck and Willis [A mathematical basis for strain-gradient theory – Part II: Tensorial plastic multiplier, 57:1045–1057; 2009, JMPS] has been an open issue, and its finite element implementation...

  5. Beta and Gamma Gradients

    DEFF Research Database (Denmark)

    Løvborg, Leif; Gaffney, C. F.; Clark, P. A.

    1985-01-01

    Experimental and/or theoretical estimates are presented concerning, (i) attenuation within the sample of beta and gamma radiation from the soil, (ii) the gamma dose within the sample due to its own radioactivity, and (iii) the soil gamma dose in the proximity of boundaries between regions...... of differing radioactivity. It is confirmed that removal of the outer 2 mm of sample is adequate to remove influence from soil beta dose and estimates are made of the error introduced by non-removal. Other evaluations include variation of the soil gamma dose near the ground surface and it appears...... that the present practice of avoiding samples above a depth of 0.3 m may be over-cautious...

  6. Kinetic studies on the reaction of cob(II)alamin with hypochlorous acid: Evidence for one electron oxidation of the metal center and corrin ring destruction.

    Science.gov (United States)

    Dassanayake, Rohan S; Farhath, Mohamed M; Shelley, Jacob T; Basu, Soumitra; Brasch, Nicola E

    2016-10-01

    Kinetic and mechanistic studies on the reaction of a major intracellular vitamin B 12 form, cob(II)alamin (Cbl(II)), with hypochlorous acid/hypochlorite (HOCl/OCl - ) have been carried out. Cbl(II) (Co(II)) is rapidly oxidized by HOCl to predominately aquacobalamin/hydroxycobalamin (Cbl(III), Co(III)) with a second-order rate constant of 2.4×10 7 M -1 s -1 (25.0°C). The stoichiometry of the reaction is 1:1. UHPLC/HRMS analysis of the product mixture of the reaction of Cbl(II) with 0.9mol equiv. HOCl provides support for HOCl being initially reduced to Cl and subsequent H atom abstraction from the corrin macrocycle occurring, resulting in small amounts of corrinoid species with two or four H atoms fewer than the parent cobalamin. Upon the addition of excess (H)OCl further slower reactions are observed. Finally, SDS-PAGE experiments show that HOCl-induced damage to bovine serum albumin does not occur in the presence of Cbl(II), providing support for Cbl(II) being an efficient HOCl trapping agent. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. MODIFIED ARMIJO RULE ON GRADIENT DESCENT AND CONJUGATE GRADIENT

    Directory of Open Access Journals (Sweden)

    ZURAIDAH FITRIAH

    2017-10-01

    Full Text Available Armijo rule is an inexact line search method to determine step size in some descent method to solve unconstrained local optimization. Modified Armijo was introduced to increase the numerical performance of several descent algorithms that applying this method. The basic difference of Armijo and its modified are in existence of a parameter and estimating the parameter that is updated in every iteration. This article is comparing numerical solution and time of computation of gradient descent and conjugate gradient hybrid Gilbert-Nocedal (CGHGN that applying modified Armijo rule. From program implementation in Matlab 6, it's known that gradient descent was applying modified Armijo more effectively than CGHGN from one side: iteration needed to reach some norm of the gradient  (input by the user. The amount of iteration was representing how long the step size of each algorithm in each iteration. In another side, time of computation has the same conclusion.

  8. Heavy Metal Contamination in Urban Soils II Comparison of Urban Park Soils Between Two Cities with Different City and Industrial Activities

    OpenAIRE

    KOMAI, Yutaka

    1981-01-01

    A comparative investigation on the state of heavy metal contamination in park soils of two cities with different city and industrial activities was carried out. Sakai and Kishiwada, both situated in southern Osaka Prefecture, were chosen as the investigated cities which had similar natural conditions but different human activities. Park soils were regarded as suitable sites for the investigation of heavy metal problem in urban environments. Samples were taken at 34 parks distributed widely in...

  9. Combining Step Gradients and Linear Gradients in Density.

    Science.gov (United States)

    Kumar, Ashok A; Walz, Jenna A; Gonidec, Mathieu; Mace, Charles R; Whitesides, George M

    2015-06-16

    Combining aqueous multiphase systems (AMPS) and magnetic levitation (MagLev) provides a method to produce hybrid gradients in apparent density. AMPS—solutions of different polymers, salts, or surfactants that spontaneously separate into immiscible but predominantly aqueous phases—offer thermodynamically stable steps in density that can be tuned by the concentration of solutes. MagLev—the levitation of diamagnetic objects in a paramagnetic fluid within a magnetic field gradient—can be arranged to provide a near-linear gradient in effective density where the height of a levitating object above the surface of the magnet corresponds to its density; the strength of the gradient in effective density can be tuned by the choice of paramagnetic salt and its concentrations and by the strength and gradient in the magnetic field. Including paramagnetic salts (e.g., MnSO4 or MnCl2) in AMPS, and placing them in a magnetic field gradient, enables their use as media for MagLev. The potential to create large steps in density with AMPS allows separations of objects across a range of densities. The gradients produced by MagLev provide resolution over a continuous range of densities. By combining these approaches, mixtures of objects with large differences in density can be separated and analyzed simultaneously. Using MagLev to add an effective gradient in density also enables tuning the range of densities captured at an interface of an AMPS by simply changing the position of the container in the magnetic field. Further, by creating AMPS in which phases have different concentrations of paramagnetic ions, the phases can provide different resolutions in density. These results suggest that combining steps in density with gradients in density can enable new classes of separations based on density.

  10. Phytoremediation of soils polluted by heavy metals and metalloids using crops: (ii early results from the in situ experiment of torviscosa (udine

    Directory of Open Access Journals (Sweden)

    Luca Marchiol

    Full Text Available Two annual high biomass yield crops – Sorghum bicolor and Helianthus annuus – were grown in a soil polluted by pyrite cinders. Specific aims of this work were: to observe the concentration of metals in plants during the crop cycle and to establish the amount of metal removal by the crops. The field trial was arranged in a randomized block design. The concentrations of heavy metals in the soil were: As 309, Cd 4.90, Co 50.9, Cu 1527, Pb 233 and Zn 980 mg kg-1. The crops received respectively mineral fertilization and organic amendment while plants in control soil did not receive any input. The phytoextraction potential of crops was estimated during the whole growth cycle; the concentration of the metals in the plant roots and in the harvestable biomass and two bioconcentration factors are reported. The amelioration of the nutritive status of soil resulted highly effective for the biomass yield but not in the concentration of metals in plant fractions. The evaluation of the potential of phytoremediation of our plants compared to other crops in terms of metal removal, was positive. Sorghum performed better than sunflower removing from the soil 220 g ha-1 of As, 5.6 g ha-1 of Cd, 30.2 g ha-1 of Co, 820 g ha-1 of Cu, 107 g ha-1 of Pb and 1944 g ha-1 of Zn.

  11. Phytoremediation of soils polluted by heavy metals and metalloids using crops: (ii early results from the in situ experiment of torviscosa (udine

    Directory of Open Access Journals (Sweden)

    Giuseppe Zerbi

    2011-02-01

    Full Text Available Two annual high biomass yield crops – Sorghum bicolor and Helianthus annuus – were grown in a soil polluted by pyrite cinders. Specific aims of this work were: to observe the concentration of metals in plants during the crop cycle and to establish the amount of metal removal by the crops. The field trial was arranged in a randomized block design. The concentrations of heavy metals in the soil were: As 309, Cd 4.90, Co 50.9, Cu 1527, Pb 233 and Zn 980 mg kg-1. The crops received respectively mineral fertilization and organic amendment while plants in control soil did not receive any input. The phytoextraction potential of crops was estimated during the whole growth cycle; the concentration of the metals in the plant roots and in the harvestable biomass and two bioconcentration factors are reported. The amelioration of the nutritive status of soil resulted highly effective for the biomass yield but not in the concentration of metals in plant fractions. The evaluation of the potential of phytoremediation of our plants compared to other crops in terms of metal removal, was positive. Sorghum performed better than sunflower removing from the soil 220 g ha-1 of As, 5.6 g ha-1 of Cd, 30.2 g ha-1 of Co, 820 g ha-1 of Cu, 107 g ha-1 of Pb and 1944 g ha-1 of Zn.

  12. Block-conjugate-gradient method

    International Nuclear Information System (INIS)

    McCarthy, J.F.

    1989-01-01

    It is shown that by using the block-conjugate-gradient method several, say s, columns of the inverse Kogut-Susskind fermion matrix can be found simultaneously, in less time than it would take to run the standard conjugate-gradient algorithm s times. The method improves in efficiency relative to the standard conjugate-gradient algorithm as the fermion mass is decreased and as the value of the coupling is pushed to its limit before the finite-size effects become important. Thus it is potentially useful for measuring propagators in large lattice-gauge-theory calculations of the particle spectrum

  13. Strain gradient crystal plasticity effects on flow localization

    DEFF Research Database (Denmark)

    Borg, Ulrik

    2007-01-01

    for metals described by the reformulated Fleck-Hutchinson strain gradient plasticity theory. The theory is implemented numerically within a finite element framework using slip rate increments and displacement increments as state variables. The formulation reduces to the classical crystal plasticity theory...... in the absence of strain gradients. The model is used to study the effect of an internal material length scale on the localization of plastic flow in shear bands in a single crystal under plane strain tension. It is shown that the mesh sensitivity is removed when using the nonlocal material model considered...

  14. Kinetics and equilibria for the formation of a new DNA metal-intercalator: the cyclic polyamine Neotrien/copper(II) complex.

    Science.gov (United States)

    Biver, Tarita; Secco, Fernando; Tinè, Maria Rosaria; Venturini, Marcella

    2004-01-01

    A study has been performed of the kinetics and equilibria involved in complex formation between the macrocyclic polyamine 2,5,8,11-tetraaza[12]-[12](2,9)[1,10]-phenanthrolinophane (Neotrien) and Cu(II) in acidic aqueous solution and ionic strength 0.5 M (NaCl), by means of the stopped-flow method and UV spectrophotometry. Spectrophotometric titrations and kinetic experiments revealed that the binding of Cu(II) to Neotrien gives rise to several 1:1 complexes differing in their degree of protonation. Under the experimental hydrogen ion concentration range investigated, complexation occurs by two parallel paths: (a) M2+ + (H4L)4+ (MH4L)6+ and (b) M2+ + (H3L)3+ (MH3L)5+. The rate constants values found for complex formation, by paths (a) and (b), are much lower than the values expected from water exchange at copper(II) and other amine/Cu(II) complexation kinetic constants. Kinetic experiments at different NaCl concentrations indicated that this finding was not due to chloride ion competition in complex formation with Neotrien, but it was related to a ring rigidity effect. As the phenanthroline moiety could, in principle, interact with nucleic acids by intercalation or external binding, some preliminary measurements concerned with the possible interactions occurring between the Cu(II)/Neotrien complex and calf thymus DNA (CT-DNA) have also been carried out. The absorption spectra of the Cu(II)/Neotrien complex change upon addition of CT-DNA at pH 7.0, revealing the occurrence of complex-nucleic acid interactions. Moreover, fluorescence titrations, carried out by adding the Cu(II)/Neotrien complex to CT-DNA, previously saturated with ethidium bromide (EB), show that the Cu(II)/Neotrien complex is able to displace EB from DNA, suggesting the complex is able to intercalate into the polynucleotide and then to cleave the phosphodiester bond of DNA.

  15. Local microstructure and flow stress in deformed metals

    DEFF Research Database (Denmark)

    Zhang, Xiaodan; Hansen, Niels; Nielsen, Chris Valentin

    2017-01-01

    The microstructure and flow stress of metals are related through many well-known strength-structure relationships based on structural parameters, where grain size and dislocation density are examples. In heterogeneous structures, the local stress and strain are important as they will affect...... the bulk properties. A microstructural method is presented which allows the local stress in a deformed metal to be estimated based on microstructural parameters determined by an EBSD analysis. These parameters are the average spacing of deformation introduced boundaries and the fraction of high angle...... boundaries. The method is demonstrated for two heterogeneous structures: (i) a gradient (sub)surface structure in steel deformed by shot peening; (ii) a heterogeneous structure introduced by friction between a tool and a workpiece of aluminum. Flow stress data are calculated based on the microstructural...

  16. Some problems in the magnetohydrodynamics of liquid metals

    International Nuclear Information System (INIS)

    Moffatt, H.K.

    1978-01-01

    When electric currents are caused to flow in an electrically conducting fluid, either by the external application of time-periodic magnetic fields or by the application of large electric potential gradients at the boundary, the associated Lorentz force is in general rotational and a fluid motion, which may be laminar or turbulent, is in general established. Three prototype problems, on which some progress has been made over the last decade, are reviewed: (i) the problem of the generation of rotation in a liquid metal by the application of a rotating magnetic field; (ii) the generation of cellular motion by the application of an alternating field of fixed direction; and (iii) the problem of the generation of fluid motion by the injection of steady current at a point electrode on the fluid boundary. All three problems are of importance in molten metal technology. (author)

  17. The causal relation between turbulent particle flux and density gradient

    Energy Technology Data Exchange (ETDEWEB)

    Milligen, B. Ph. van; Martín de Aguilera, A.; Hidalgo, C. [CIEMAT - Laboratorio Nacional de Fusión, Avda. Complutense 40, 28040 Madrid (Spain); Carreras, B. A. [BACV Solutions, 110 Mohawk Road, Oak Ridge, Tennessee 37830 (United States); García, L.; Nicolau, J. H. [Universidad Carlos III, 28911 Leganés, Madrid (Spain)

    2016-07-15

    A technique for detecting the causal relationship between fluctuating signals is used to investigate the relation between flux and gradient in fusion plasmas. Both a resistive pressure gradient driven turbulence model and experimental Langmuir probe data from the TJ-II stellarator are studied. It is found that the maximum influence occurs at a finite time lag (non-instantaneous response) and that quasi-periodicities exist. Furthermore, the model results show very long range radial influences, extending over most of the investigated regions, possibly related to coupling effects associated with plasma self-organization. These results clearly show that transport in fusion plasmas is not local and instantaneous, as is sometimes assumed.

  18. Morphogengineering roots: comparing mechanisms of morphogen gradient formation

    Science.gov (United States)

    2012-01-01

    Background In developmental biology, there has been a recent focus on the robustness of morphogen gradients as possible providers of positional information. It was shown that functional morphogen gradients present strong biophysical constraints and lack of robustness to noise. Here we explore how the details of the mechanism which underlies the generation of a morphogen gradient can influence those properties. Results We contrast three gradient-generating mechanisms, (i) a source-decay mechanism; and (ii) a unidirectional transport mechanism; and (iii) a so-called reflux-loop mechanism. Focusing on the dynamics of the phytohormone auxin in the root, we show that only the reflux-loop mechanism can generate a gradient that would be adequate to supply functional positional information for the Arabidopsis root, for biophysically reasonable kinetic parameters. Conclusions We argue that traits that differ in spatial and temporal time-scales can impose complex selective pressures on the mechanism of morphogen gradient formation used for the development of the particular organism. PMID:22583698

  19. Spatial gradient tuning in metamaterials

    Science.gov (United States)

    Driscoll, Tom; Goldflam, Michael; Jokerst, Nan; Basov, Dimitri; Smith, David

    2011-03-01

    Gradient Index (GRIN) metamaterials have been used to create devices inspired by, but often surpassing the potential of, conventional GRIN optics. The unit-cell nature of metamaterials presents the opportunity to exert much greater control over spatial gradients than is possible in natural materials. This is true not only during the design phase but also offers the potential for real-time reconfiguration of the metamaterial gradient. This ability fits nicely into the picture of transformation-optics, in which spatial gradients can enable an impressive suite of innovative devices. We discuss methods to exert control over metamaterial response, focusing on our recent demonstrations using Vanadium Dioxide. We give special attention to role of memristance and mem-capacitance observed in Vanadium Dioxide, which simplify the demands of stimuli and addressing, as well as intersecting metamaterials with the field of memory-materials.

  20. Low-gradient aortic stenosis.

    Science.gov (United States)

    Clavel, Marie-Annick; Magne, Julien; Pibarot, Philippe

    2016-09-07

    An important proportion of patients with aortic stenosis (AS) have a 'low-gradient' AS, i.e. a small aortic valve area (AVA gradient (gradient discrepancy raises uncertainty about the actual stenosis severity and thus about the indication for aortic valve replacement (AVR) if the patient has symptoms and/or left ventricular (LV) systolic dysfunction. The most frequent cause of low-gradient (LG) AS is the presence of a low LV outflow state, which may occur with reduced left ventricular ejection fraction (LVEF), i.e. classical low-flow, low-gradient (LF-LG), or preserved LVEF, i.e. paradoxical LF-LG. Furthermore, a substantial proportion of patients with AS may have a normal-flow, low-gradient (NF-LG) AS: i.e. a small AVA-low-gradient combination but with a normal flow. One of the most important clinical challenges in these three categories of patients with LG AS (classical LF-LG, paradoxical LF-LG, and NF-LG) is to differentiate a true-severe AS that generally benefits from AVR vs. a pseudo-severe AS that should be managed conservatively. A low-dose dobutamine stress echocardiography may be used for this purpose in patients with classical LF-LG AS, whereas aortic valve calcium scoring by multi-detector computed tomography is the preferred modality in those with paradoxical LF-LG or NF-LG AS. Although patients with LF-LG severe AS have worse outcomes than those with high-gradient AS following AVR, they nonetheless display an important survival benefit with this intervention. Some studies suggest that transcatheter AVR may be superior to surgical AVR in patients with LF-LG AS. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

  1. Non-destructive pollution exposure assessment in the European hedgehog (Erinaceus europaeus): II. Hair and spines as indicators of endogenous metal and As concentrations.

    Science.gov (United States)

    D'Havé, Helga; Scheirs, Jan; Mubiana, Valentine Kayawe; Verhagen, Ron; Blust, Ronny; De Coen, Wim

    2006-08-01

    The role of hair and spines of the European hedgehog as non-destructive monitoring tools of metal (Ag, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb, Zn) and As pollution in terrestrial ecosystems was investigated. Our results showed that mean pollution levels of a random sample of hedgehogs in Flanders are low to moderate. Yet, individual hedgehogs may be at risk for metal toxicity. Tissue distribution analyses (hair, spines, liver, kidney, muscle and fat tissue) indicated that metals and As may reach considerable concentrations in external tissues, such as hair and spines. Positive relationships were observed between concentrations in hair and those in liver, kidney and muscle for Al, Co, Cr, Cu, and Pb (0.43 Spine concentrations were positively related to liver, kidney and muscle concentrations for Cd, Co, Cr, Cu and Pb (0.37 spine Ag, Al, As and Fe were related to metal concentrations in one or two of the investigated internal tissues (0.31 hedgehogs when concentrations in hair or spines are available. The present study demonstrated the possibility of using hair and spines for non-destructive monitoring of metal and As pollution in hedgehogs.

  2. Humic acids and their interactions with metallic elements: Cu II, Eu III, Th IV, U VI: contribution of size exclusion chromatography method and research of complexation models

    International Nuclear Information System (INIS)

    Lesourd-Moulin, V.

    1986-04-01

    The interest given to natural organic matter (humic and fulvic acids) as complexing agents of metallic ions in soils and natural waters becomes more and more important in environmental area. Cation - humic matter interactions have a great importance, a better understanding of the contribution of these substances in natural media specially towards radioactive elements with long life time. Interactions are studied by a chromatographic technique of gel filtration: the dynamic equilibrium method is based on the separation of the formed complex humic macromolecule - metallic ion and the free metallic ion, which due to its size penetrates totally in the pores of the gel. Separation mechanisms of the chromatographic support and the contribution of each parameter, are studied as a function of the buffer nature, its concentration, the PH, the gel porosity and the valence of the metallic cation. This study led to the determination of the appropriate experimental conditions for each cation. A study of metallic binding with humic acid has been undertaken with Cu 2+ , Eu 3+ , Th 4+ , Uo 2 2+ . These elements, except copper, have been chosen for their properties similar to the transuranic elements. Different samples of humic acids (commercial, podzolic soil, rendzine soil) are also studied. A deeper research of europium - humic acid interactions by means of different treatment models (discrete or gaussian models) has been undertaken in order to determine the number, the binding site strength and the global interaction constants [fr

  3. Graded/Gradient Porous Biomaterials

    Directory of Open Access Journals (Sweden)

    Xigeng Miao

    2009-12-01

    Full Text Available Biomaterials include bioceramics, biometals, biopolymers and biocomposites and they play important roles in the replacement and regeneration of human tissues. However, dense bioceramics and dense biometals pose the problem of stress shielding due to their high Young’s moduli compared to those of bones. On the other hand, porous biomaterials exhibit the potential of bone ingrowth, which will depend on porous parameters such as pore size, pore interconnectivity, and porosity. Unfortunately, a highly porous biomaterial results in poor mechanical properties. To optimise the mechanical and the biological properties, porous biomaterials with graded/gradient porosity, pores size, and/or composition have been developed. Graded/gradient porous biomaterials have many advantages over graded/gradient dense biomaterials and uniform or homogenous porous biomaterials. The internal pore surfaces of graded/gradient porous biomaterials can be modified with organic, inorganic, or biological coatings and the internal pores themselves can also be filled with biocompatible and biodegradable materials or living cells. However, graded/gradient porous biomaterials are generally more difficult to fabricate than uniform or homogenous porous biomaterials. With the development of cost-effective processing techniques, graded/gradient porous biomaterials can find wide applications in bone defect filling, implant fixation, bone replacement, drug delivery, and tissue engineering.

  4. Dose gradient curve: A new tool for evaluating dose gradient.

    Science.gov (United States)

    Sung, KiHoon; Choi, Young Eun

    2018-01-01

    Stereotactic radiotherapy, which delivers an ablative high radiation dose to a target volume for maximum local tumor control, requires a rapid dose fall-off outside the target volume to prevent extensive damage to nearby normal tissue. Currently, there is no tool to comprehensively evaluate the dose gradient near the target volume. We propose the dose gradient curve (DGC) as a new tool to evaluate the quality of a treatment plan with respect to the dose fall-off characteristics. The average distance between two isodose surfaces was represented by the dose gradient index (DGI) estimated by a simple equation using the volume and surface area of isodose levels. The surface area was calculated by mesh generation and surface triangulation. The DGC was defined as a plot of the DGI of each dose interval as a function of the dose. Two types of DGCs, differential and cumulative, were generated. The performance of the DGC was evaluated using stereotactic radiosurgery plans for virtual targets. Over the range of dose distributions, the dose gradient of each dose interval was well-characterized by the DGC in an easily understandable graph format. Significant changes in the DGC were observed reflecting the differences in planning situations and various prescription doses. The DGC is a rational method for visualizing the dose gradient as the average distance between two isodose surfaces; the shorter the distance, the steeper the dose gradient. By combining the DGC with the dose-volume histogram (DVH) in a single plot, the DGC can be utilized to evaluate not only the dose gradient but also the target coverage in routine clinical practice.

  5. Determination of heavy metal deposition in the county of Obrenovac (Serbia using mosses as bioindicators II: Cadmium (CD, cobalt (CO, and chromium (CR

    Directory of Open Access Journals (Sweden)

    Vukojević V.

    2006-01-01

    Full Text Available In the present study, the deposition of three heavy metals (Cd, Co and Cr in the county of Obrenovac (Serbia is determined using four moss taxa (Bryum argenteum, Bryum capillare, Brachythecium sp. and Hypnum cupressiforme as bioindicators. Distribution of average heavy metal content in all mosses in the county of Obrenovac is presented in maps, while long term atmospheric deposition (in the mosses Bryum argenteum and B. capillare and short term atmospheric deposition (in the mosses Brachythecium sp. and Hypnum cupressiforme are discussed and in tables. Areas of the highest contaminations are highlighted.

  6. Fano resonances from gradient-index metamaterials.

    Science.gov (United States)

    Xu, Yadong; Li, Sucheng; Hou, Bo; Chen, Huanyang

    2016-01-27

    Fano resonances - resonant scattering features with a characteristic asymmetric profile - have generated much interest, due to their extensive and valuable applications in chemical or biological sensors, new types of optical switches, lasers and nonlinear optics. They have been observed in a wide variety of resonant optical systems, including photonic crystals, metamaterials, metallic gratings and nanostructures. In this work, a waveguide structure is designed by employing gradient-index metamaterials, supporting strong Fano resonances with extremely sharp spectra. As the changes in the transmission spectrum originate from the interaction of guided modes from different channels, instead of resonance structures or metamolecules, the Fano resonances can be observed for both transverse electric and transverse magnetic polarizations. These findings are verified by fine agreement with analytical calculations and experimental results at microwave, as well as simulated results at near infrared frequencies.

  7. Design and synthesis of a tetradentate '3-amine-1-carboxylate' ligand to mimic the metal binding environment at the non-heme iron(II) oxidase active site.

    Science.gov (United States)

    Dungan, Victoria J; Ortin, Yannick; Mueller-Bunz, Helge; Rutledge, Peter J

    2010-04-07

    Non-heme iron(II) oxidases (NHIOs) catalyse a diverse array of oxidative chemistry in Nature. As part of ongoing efforts to realize biomimetic, iron-mediated C-H activation, we report the synthesis of a new 'three-amine-one-carboxylate' ligand designed to complex with iron(II) and mimic the NHIO active site. The tetradentate ligand has been prepared as a single enantiomer in nine synthetic steps from N-Cbz-L-alanine, pyridine-2,6-dimethanol and diphenylamine, using Seebach oxazolidinone chemistry to control the stereochemistry. X-Ray crystal structures are reported for two important intermediates, along with variable temperature NMR experiments to probe the hindered interconversion of conformational isomers of several key intermediates, 2,6-disubstituted pyridine derivatives. The target ligand and an N-Cbz-protected precursor were each then complexed with iron(II) and tested for their ability to promote alkene dihydroxylation, using hydrogen peroxide as the oxidant.

  8. Improving the performance of IPMCs with a gradient in thickness

    International Nuclear Information System (INIS)

    Zhao, Yang; Xu, Bing; Zheng, Gaofeng; Zheng, Jianyi; Qiu, Xiaochun; Zhuang, Mingfeng; Sun, Daoheng

    2013-01-01

    An ionic polymer metal composite (IPMC) is a kind of electro-active polymer. Due to the properties of low driving voltage, large deformation, flexibility and lightness, it is becoming one of the more popular from a diversity of smart materials. In this study, a novel structure of Nafion ® film is proposed to improve the performance of an IPMC. IPMC samples with a gradient structure in thickness are fabricated and their performance is investigated to confirm the validity of the gradient structure. The deformation displacement and the blocking force are compared under AC and DC voltage by experiments. The results indicate that the structure of gradient in thickness would improve the performance both in deformation displacement and blocking force. (paper)

  9. A Bis-Triazacyclononane Tris-Pyridyl N9 -Azacryptand "Beer Can" Receptor for Complexation of Alkali Metal and Lead(II) Cations.

    Science.gov (United States)

    Brown, Asha; Bunchuay, Thanthapatra; Crane, Christopher G; White, Nicholas G; Thompson, Amber L; Beer, Paul D

    2018-04-18

    A new bis-triazacyclononane tris-pyridyl N 9 -azacryptand ligand is prepared via a convenient one-pot [2+3] condensation reaction between triazacyclononane and 2,6-bis(bromomethyl) pyridine in the presence of M 2 CO 3 (M=Li, Na, K). The proton, lithium, sodium, potassium and lead(II) complexes of the ligand are characterised in the solid state. Preliminary solution-phase competition experiments indicate that the cryptand ligand preferentially binds lead(II) in the presence of sodium, calcium, potassium and zinc cations in methanol solution. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Light-Induced Copper(II) Coordination by a Bicyclic Tetraaza Chelator through a Ligand-to-Metal Charge-Transfer Reaction

    DEFF Research Database (Denmark)

    Holm-Jørgensen, Jacob Rørdam; Jensen, Mikael; Bjerrum, Morten J.

    2011-01-01

    coordinated amine groups) at pH above 6. These findings are supported by pH titrations of mixtures of Cu2+ and [24.31]adz in water. Irradiation of this complex in the ligand-to-metal charge-transfer (LMCT) band by a diode-array spectrophotometer leads to photodeprotonation and subsequently to formation...

  11. Comparison of an everolimus-eluting bioresorbable scaffold with an everolimus-eluting metallic stent for the treatment of coronary artery stenosis (ABSORB II)

    DEFF Research Database (Denmark)

    Serruys, Patrick W; Chevalier, Bernard; Sotomi, Yohei

    2016-01-01

    BACKGROUND: No medium-term data are available on the random comparison between everolimus-eluting bioresorbable vascular scaffolds and everolimus-eluting metallic stents. The study aims to demonstrate two mechanistic properties of the bioresorbable scaffold: increase in luminal dimensions as a re...

  12. Cytoskeletal alterations in interphase cells of the green alga Spirogyra decimina in response to heavy metals exposure: II. The effect of aluminium, nickel and copper

    Czech Academy of Sciences Publication Activity Database

    Přibyl, Pavel; Cepák, Vladislav; Zachleder, Vilém

    2008-01-01

    Roč. 22, č. 5 (2008), s. 1160-1168 ISSN 0887-2333 R&D Projects: GA MŠk 1M0571 Institutional research plan: CEZ:AV0Z60050516; CEZ:AV0Z50200510 Keywords : cytoskeleton * heavy metals * Spirogyra Subject RIV: EF - Botanics Impact factor: 2.473, year: 2008

  13. Synthesis and physical and chemical properties of poly-hydro-aluminates and poly-halogen-aluminates metals of II A group

    International Nuclear Information System (INIS)

    Khudoydodov, B.O.

    1990-01-01

    The purpose of the present work is investigation of conditions and mechanism of passing of formation reactions of aluminum hydrides, poly-hydride-aluminates and poly-halogen-aluminates of alkaline-earth metals and magnesium and studying of their physical and chemical properties

  14. Influence of urban runoff, inappropriate waste disposal practices and World War II on the heavy metal status of sediments in the southern half of Saipan Lagoon, Saipan, CNMI

    International Nuclear Information System (INIS)

    Denton, Gary R.W.; Emborski, Carmen A.; Habana, Nathan C.; Starmer, John A.

    2014-01-01

    Highlights: • Heavy metals were examined in sediments from the southern half of Saipan Lagoon. • This area is chronically impacted by stormwater discharges all along the coast. • Generally, the study identified moderate metal enrichment that attenuated seawards. • Mercury distributions within the lagoon also seemed to reflect past WWII activities. • Additional Pb, Cu and Zn inputs at the S end of the lagoon came from an old dumpsite. - Abstract: Heavy metals were examined in sediments from the southern half of Saipan Lagoon. These waters provided tactical access for US troops during WWII and were heavily shelled at the time. Mercury profiles in sediments were, to some extent, reflective of this event. Samples from the southern end of the lagoon, where an old post-war du