Study of interaction in systems of MoCl/sub 5/-MeCl/sub 2/ (Me - Sn, Zn, Cd, Hg) - a solvent

Energy Technology Data Exchange (ETDEWEB)

Golub, A M; Trachevskii, V V; Ul' ko, N V [Kievskij Gosudarstvennyj Univ. (Ukrainian SSR)

1978-04-01

Interaction of Mo(5) with dichlorides of tin, zinc, cadmium and mercury in organic solvents was studied by preparative methods, by electron, epr, infrared spectrometry and by conductometry. A polynuclear diamagnetic compound with Mo(5):Sn(2) ratio of 2:1 formed in acetone. A coordination polynuclear compound of (MoOCl/sub 3/)/sub 2/xSnCl/sub 2/x2CH/sub 3/CN was isolated from acetonitrile. It is shown that formation of solvate-chloride and solvate complexes of Mo(5) in solvents depends both on the solvating capacity of the solvent and on stability of the MeCl/sup -3/ (Me is Sn, Zn, Cd, Hg) chloride complex, which grows in the Zn < Sn < Cd < Hg series.

Unprecedented linking of two polyoxometalate units with a metal-metal multiple bond.

Science.gov (United States)

Sokolov, Maxim N; Korenev, Vladimir S; Izarova, Natalya V; Peresypkina, Eugenia V; Vicent, Cristian; Fedin, Vladimir P

2009-03-02

The reaction of (Bu(4)N)(2)[Re(2)Cl(8)] with lacunary Keggin polyoxometalate K(7)[PW(11)O(39)] in water produces a new dumbbell-shaped heteropolyoxometalate anion, [Re(2)(PW(11)O(39))(2)](8-), whose structure contains a central Re(2) core with a quadruple bond between Re atoms (Re-Re 2.25 A), coordinated to two polyoxometalate units. This complex represents the first example of the direct linking of two polyoxometalate units via a metal-metal multiple bond. The compounds were characterized by X-ray analysis, IR, and electrospray ionization mass spectrometry.

Microsolvation of methylmercury: structures, energies, bonding and NMR constants ((199)Hg, (13)C and (17)O).

Science.gov (United States)

Flórez, Edison; Maldonado, Alejandro F; Aucar, Gustavo A; David, Jorge; Restrepo, Albeiro

2016-01-21

Hartree-Fock (HF) and second order perturbation theory (MP2) calculations within the scalar and full relativistic frames were carried out in order to determine the equilibrium geometries and interaction energies between cationic methylmercury (CH3Hg(+)) and up to three water molecules. A total of nine structures were obtained. Bonding properties were analyzed using the Quantum Theory of Atoms In Molecules (QTAIM). The analyses of the topology of electron densities reveal that all structures exhibit a partially covalent HgO interaction between methylmercury and one water molecule. Consideration of additional water molecules suggests that they solvate the (CH3HgOH2)(+) unit. Nuclear magnetic shielding constants σ((199)Hg), σ((13)C) and σ((17)O), as well as indirect spin-spin coupling constants J((199)Hg-(13)C), J((199)Hg-(17)O) and J((13)C-(17)O), were calculated for each one of the geometries. Thermodynamic stability and the values of NMR constants correlate with the ability of the system to directly coordinate oxygen atoms of water molecules to the mercury atom in methylmercury and with the formation of hydrogen bonds among solvating water molecules. Relativistic effects account for 11% on σ((13)C) and 14% on σ((17)O), which is due to the presence of Hg (heavy atom on light atom, HALA effect), while the relativistic effects on σ((199)Hg) are close to 50% (heavy atom on heavy atom itself, HAHA effect). J-coupling constants are highly influenced by relativity when mercury is involved as in J((199)Hg-(13)C) and J((199)Hg-(17)O). On the other hand, our results show that the values of NMR constants for carbon and oxygen, atoms which are connected through mercury (C-HgO), are highly correlated and are greatly influenced by the presence of water molecules. Water molecules introduce additional electronic effects to the relativistic effects due to the mercury atom.

Bad metal behaviour in the new Hg-rich amalgam KHg{sub 6} with polar metallic bonding

Energy Technology Data Exchange (ETDEWEB)

Tambornino, Frank; Hoch, Constantin, E-mail: constantin.hoch@cup.uni-muenchen.de

2015-01-05

Highlights: • The novel Hg-rich amalgam KHg{sub 6} was synthesised by electrocrystallisation. • The structure was investigated by single crystal and powder diffraction. • Thermal decomposition, electric resistance and magnetic susceptibiliy were examined. • Band structure, total and partial density of states and Bader charges were calculated. • Bad metal behaviour results from ionic, metallic and covalent bonding contributions. - Abstract: The new mercury-rich amalgam KHg{sub 6} crystallises with the BaHg{sub 6} structure type (orthorhombic, space group Pnma (No. 62), a = 13.394(9) Å, b = 5.270(3) Å, c = 10.463 Å). It was prepared by electrolysis of a solution of KI in N,N′-Dimethylformamide at 343 K at a reactive Hg cathode. The structure of KHg{sub 6} shows motifs of ionic packing, covalent Hg cluster formation and metallic properties. KHg{sub 6} decomposes peritectically at 443 K. The combination of alkali metals with a noble metal with moderate electron affinity results in the formation of polar metal–metal bonding with considerable but incomplete electron transfer from the electropositive to the electronegative sublattice, resulting in typical “bad metal behaviour”, illustrated by resistance and susceptibility measurements and quantum theoretical calculations.

Mechanism of Hg(II) Immobilization in Sediments by Sulfate-Cement Amendment.

Science.gov (United States)

Serrano, Susana; Vlassopoulos, Dimitri; O'Day, Peggy A

2016-04-01

Reactive amendments such as Portland and super-sulfate cements offer a promising technology for immobilizing metalloid contaminants such as mercury (Hg) in soils and sediments through sequestration in less bioavailable solid forms. Tidal marsh sediments were reacted with dissolved Hg(II) in synthetic seawater and fresh water solutions, treated with Portland cement and FeSO 4 amendment, and aged for up to 90 days. Reacted solids were analyzed with bulk sequential extraction methods and characterized by powder X-ray diffraction (XRD), electron microscopy, and synchrotron X-ray absorption spectroscopy at the Hg L III - and S K-edge. In amended sediments, XRD, SEM and sulfur K-edge XANES indicated formation of gypsum in seawater experiments or ettringite-type (Ca 6 Al 2 (SO 4 ) 3 (OH) 12 . 26H 2 O) phases in fresh water experiments, depending on the final solution pH (seawater ∼8.5; freshwater ∼10.5). Analysis of Hg EXAFS spectra showed Cl and Hg ligands in the first- and second-coordination shells at distances characteristic of a polynuclear chloromercury(II) salt, perhaps as a nanoparticulate phase, in both seawater and fresh water experiments. In addition to the chloromercury species, a smaller fraction (∼20-25%) of Hg was bonded to O atoms in fresh water sample spectra, suggesting the presence of a minor sorbed Hg fraction. In the absence of amendment treatment, Hg sorption and resistance to extraction can be accounted for by relatively strong binding by reduced S species present in the marsh sediment detected by S XANES. Thermodynamic calculations predict stable aqueous Hg-Cl species at seawater final pH, but higher final pH in fresh water favors aqueous Hg-hydroxide species. The difference in Hg coordination between aqueous and solid phases suggests that the initial Hg-Cl coordination was stabilized in the cement hydration products and did not re-equilibrate with the bulk solution with aging. Collectively, results suggest physical encapsulation of Hg as a

Fully relativistic coupled cluster and DFT study of electric field gradients at Hg in 199Hg compounds

DEFF Research Database (Denmark)

Arcisauskaité, Vaida; Knecht, Stefan; Sauer, Stephan P. A.

2012-01-01

We investigate the magnitude and interplay of relativistic and electron correlation effects on the electric field gradient (EFG) at the position of Hg in linear and bent HgL2 (L=CH3, Cl, Br, I) and trigonal planar [HgCl3]- complexes using four-component relativistic Dirac-Coulomb (DC) and non...

Inflation, Index-Linked Bonds, and Asset Allocation

OpenAIRE

Zvi Bodie

1988-01-01

The recent introduction of CPI-linked bonds by several financial institutions is a milestone in the history of the U.S. financial system. It has potentially far-reaching effects on individual and institutional asset allocation decisions because these securities represent the only true long-run hedge against inflation risk. CPI-linked bonds make possible the creation of additional financial innovations that would use them as the asset base. One such innovation that seems likely is inflation-pr...

The Role of Inflation-Linked Bonds. Increasing, but Still Modest

NARCIS (Netherlands)

Westerhout, Ed; Ciocyte, Ona

2017-01-01

Although the market for inflation-linked bonds has expanded enormously, nominal bonds are still the main instrument to finance public debts. This paper seeks to explain why. It focuses on the Eurozone countries for which the standard argument that inflation-linked bonds may help to reduce inflation

Etude structurale et vibrationnelle d'un nouveau composé complexe de cobalt: [Co(imidazole)4Cl]Cl.

Science.gov (United States)

Derbel, Amira; Mhiri, Tahar; Graia, Mohsen

2015-10-01

In the title complex, chlorido-tetra-kis-(1H-imidazole-κN (3))cobalt(II) chloride, [CoCl(C3H4N2)4]Cl, the Co(II) cation has a distorted square-pyramidal coordination environment. It is coordinated by four N atoms of four imidazole (Im) groups in the basal plane, and by a Cl atom in the apical position. It is isostructural with [Cu(Im)4Cl]Cl [Morzyk-Ociepa et al. (2012 ▸). J. Mol. Struct. 1028, 49-56] and [Cu(Im)4Br]Br [Hossaini Sadr et al. (2004 ▸). Acta Cryst. E60, m1324-m1326]. In the crystal, the [CoCl(C3H4N2)4](+) cations and Cl(-) anions are linked via N-H⋯Cl hydrogen bonds, forming layers parallel to (010). These layers are linked via C-H⋯Cl hydrogen bonds and C-H⋯π and π-π [inter-centroid distance = 3.794 (2) Å] inter-actions, forming a three-dimensional framework. The IR spectrum shows vibrational bands typical for imidazol groups. The monoclinic unit cell of the title compound emulates an ortho-rhom-bic cell as its β angle is close to 90°. The crystal is twinned, with the refined ratio of twin components being 0.569 (1):0.431 (1).

Notes on the dosimetry and toxicity of 197HgCl2

International Nuclear Information System (INIS)

Valeyre, J.

1976-01-01

The interest raised by quantitative kidney scintigraphy lies to a large extent in the fact that the renal cortex fixes mercury very strongly. Under these conditions it is logical to evaluate as accurately as possible the dose absorbed not only by the kidneys but also by the ovaries, situated near-by. The different calculations presented show a total absorbed dose of 32 to 98mrads/μCi in the kidney. The average total dose absorbed by each ovary varies from 0.038 in adults to 0.136mrad/μCi in young children. Recent preparations of 197 HgCl 2 contain 2 to 5μg mercury per 150μCi. The toxicity of mercury should in no case be considered a problem [fr

Transition from metal-ligand bonding to halogen bonding involving a metal as halogen acceptor a study of Cu, Ag, Au, Pt, and Hg complexes

Science.gov (United States)

Oliveira, Vytor; Cremer, Dieter

2017-08-01

Utilizing all-electron Dirac-exact relativistic calculations with the Normalized Elimination of the Small Component (NESC) method and the local vibrational mode approach, the transition from metal-halide to metal halogen bonding is determined for Au-complexes interacting with halogen-donors. The local stretching force constants of the metal-halogen interactions reveal a smooth transition from weak non-covalent halogen bonding to non-classical 3-center-4-electron bonding and finally covalent metal-halide bonding. The strongest halogen bonds are found for dialkylaurates interacting with Cl2 or FCl. Differing trends in the intrinsic halogen-metal bond strength, the binding energy, and the electrostatic potential are explained.

HgCl{sub 2} sorption on lignite activated carbon: Analysis of fixed-bed results

Energy Technology Data Exchange (ETDEWEB)

Mibeck, Blaise A.F.; Olson, Edwin S.; Miller, Stanley J. [University of North Dakota Energy and Environmental Research Center, 15 North 23rd Street, Stop 9018, Grand Forks, ND 58202-9018 (United States)

2009-11-15

Factors that influence kinetic reactivity and equilibrium between elemental mercury, carbon, and flue gas components have been the focus of numerous studies. This study pertains to recent bench-scale fixed-bed tests in which activated carbon was exposed to HgCl{sub 2} in a flue gas composition typical of an unscrubbed eastern bituminous coal. Results are discussed in light of a refined binding site model based on the zigzag carbene structures recently proposed for electronic states at the edges of the carbon graphene layers. (author)

Proteomic approach for identifying gonad differential proteins in the oyster (Crassostrea angulata) following food-chain contamination with HgCl2.

Science.gov (United States)

Zhang, Qing-Hong; Huang, Lin; Zhang, Yong; Ke, Cai-Huan; Huang, He-Qing

2013-12-06

Hg discharged into the environmental waters can generally be bioaccumulated, transformed and transmited by living organisms, thus resulting in the formation of Hg-toxicity food chains. The pathway and toxicology of food chain contaminated with environmental Hg are rarely revealed by proteomics. Here, we showed that differential proteomics had the potential to understand reproduction toxicity mechanism in marine molluscs through the Hg-contaminated food chain. Hg bioaccumulation was found in every link of the HgCl2-Chlorella vulgaris-oyster-mice food chain. Morphological observations identified the lesions in both the oyster gonad and the mice ovary. Differential proteomics was used to study the mechanisms of Hg toxicity in the oyster gonad and to find some biomarkers of Hg contamination in food chain. Using 2-DE and MALDI-TOF/TOF MS, we identified 13 differential protein spots, of which six were up-regulated, six were down-regulated, while one was undecided. A portion of these differential proteins was further confirmed using real-time PCR and western blotting methods. Their major functions involved binding, protein translocation, catalysis, regulation of energy metabolism, reproductive functioning and structural molecular activity. Among these proteins, 14-3-3 protein, GTP binding protein, arginine kinase (AK) and 71kDa heat shock connate protein (HSCP 71) are considered to be suitable biomarkers of environmental Hg contamination. Furthermore, we established the gene correspondence, responding to Hg reproductive toxicity, between mouse and oyster, and then used real-time PCR to analyze mRNA differential expression of the corresponding genes in mice. The results indicated that the mechanism of Hg reproductive toxicity in mouse was similar to that in oyster. We suggest that the proteomics would be further developed in application research of food safety including toxicological mechanism. It is well known that mercury (Hg) is one of the best toxic metal elements in

Bonds with index-linked stochastic coupons in quantum finance

Science.gov (United States)

Baaquie, Belal Ehsan

2018-06-01

An index-linked coupon bond is defined that pays coupons whose values are stochastic, depending on a market defined index. This is an asset class distinct from the existing coupon bonds. The index-linked coupon bond is an example of a sukuk, which is an instrument that implements one of the cornerstones of Islamic finance (Askari et al., 2012): that an investor must share in the risk of the issuer in order to earn profits from the investment. The index-linked coupon bond is defined using the mathematical framework of quantum finance (Baaquie, 2004, 2010). The coupons are stochastic, with the quantum of coupon payments depending on a publicly traded index that is chosen to reflect the primary drivers of the revenues of the issuer of the bond. The index ensures there is information symmetry - regarding the quantum of coupon being paid - between issuer and investor. The dependence of the coupon on the index is designed so that the variation of the index mirrors the changing fortunes of the issuer, with the coupon's quantum increasing for increasing values of the index and conversely, decreasing with a fall of the index.

Parametrization of Combined Quantum Mechanical and Molecular Mechanical Methods: Bond-Tuned Link Atoms

Directory of Open Access Journals (Sweden)

Xin-Ping Wu

2018-05-01

Full Text Available Combined quantum mechanical and molecular mechanical (QM/MM methods are the most powerful available methods for high-level treatments of subsystems of very large systems. The treatment of the QM−MM boundary strongly affects the accuracy of QM/MM calculations. For QM/MM calculations having covalent bonds cut by the QM−MM boundary, it has been proposed previously to use a scheme with system-specific tuned fluorine link atoms. Here, we propose a broadly parametrized scheme where the parameters of the tuned F link atoms depend only on the type of bond being cut. In the proposed new scheme, the F link atom is tuned for systems with a certain type of cut bond at the QM−MM boundary instead of for a specific target system, and the resulting link atoms are call bond-tuned link atoms. In principle, the bond-tuned link atoms can be as convenient as the popular H link atoms, and they are especially well adapted for high-throughput and accurate QM/MM calculations. Here, we present the parameters for several kinds of cut bonds along with a set of validation calculations that confirm that the proposed bond-tuned link-atom scheme can be as accurate as the system-specific tuned F link-atom scheme.

Parametrization of Combined Quantum Mechanical and Molecular Mechanical Methods: Bond-Tuned Link Atoms.

Science.gov (United States)

Wu, Xin-Ping; Gagliardi, Laura; Truhlar, Donald G

2018-05-30

Combined quantum mechanical and molecular mechanical (QM/MM) methods are the most powerful available methods for high-level treatments of subsystems of very large systems. The treatment of the QM-MM boundary strongly affects the accuracy of QM/MM calculations. For QM/MM calculations having covalent bonds cut by the QM-MM boundary, it has been proposed previously to use a scheme with system-specific tuned fluorine link atoms. Here, we propose a broadly parametrized scheme where the parameters of the tuned F link atoms depend only on the type of bond being cut. In the proposed new scheme, the F link atom is tuned for systems with a certain type of cut bond at the QM-MM boundary instead of for a specific target system, and the resulting link atoms are call bond-tuned link atoms. In principle, the bond-tuned link atoms can be as convenient as the popular H link atoms, and they are especially well adapted for high-throughput and accurate QM/MM calculations. Here, we present the parameters for several kinds of cut bonds along with a set of validation calculations that confirm that the proposed bond-tuned link-atom scheme can be as accurate as the system-specific tuned F link-atom scheme.

Analyzing velocity map images to distinguish the primary methyl photofragments from those produced upon C-Cl bond photofission in chloroacetone at 193 nm

Science.gov (United States)

Alligood, Bridget W.; Straus, Daniel B.; Butler, Laurie J.

2011-07-01

We use a combination of crossed laser-molecular beam scattering experiments and velocity map imaging experiments to investigate the three primary photodissociation channels of chloroacetone at 193 nm: C-Cl bond photofission yielding CH3C(O)CH2 radicals, C-C bond photofission yielding CH3CO and CH2Cl products, and C-CH3 bond photofission resulting in CH3 and C(O)CH2Cl products. Improved analysis of data previously reported by our group quantitatively identifies the contribution of this latter photodissociation channel. We introduce a forward convolution procedure to identify the portion of the signal, derived from the methyl image, which results from a two-step process in which C-Cl bond photofission is followed by the dissociation of the vibrationally excited CH3C(O)CH2 radicals to CH3 + COCH2. Subtracting this from the total methyl signal identifies the methyl photofragments that result from the CH3 + C(O)CH2Cl photofission channel. We find that about 89% of the chloroacetone molecules undergo C-Cl bond photofission to yield CH3C(O)CH2 and Cl products; approximately 8% result in C-C bond photofission to yield CH3CO and CH2Cl products, and the remaining 2.6% undergo C-CH3 bond photofission to yield CH3 and C(O)CH2Cl products.

Metal-metal bonded compounds. V. Compounds with Ir (Rh)-Hg bonds containing a bridging and a chelating triazenido group which interconvert intramolecularly

NARCIS (Netherlands)

Koten, G. van; Vliet, P.I. van; Kokkes, M.; Vrieze, K.

1980-01-01

The compounds [(Diene)(RN{3}R'){2}MHgCl]{2} (M = Ir; Diene = COD; R = CH{3}, C{2}H{5}; R' = p-CH{3}C{6}H{4} and M = Rh; Diene = COD, NOR; R = CH{3}, C{2}H{5}, p-CH{3}-C{6}H{4}; R' = p-CH{3}C{6}H{4} have been prepared by reaction of [(Diene)MCl]{2} with [Hg(RN{3}R'){2}] and by reaction of

Two-center three-electron bonding in ClNH{sub 3} revealed via helium droplet infrared laser Stark spectroscopy: Entrance channel complex along the Cl + NH{sub 3} → ClNH{sub 2} + H reaction

Energy Technology Data Exchange (ETDEWEB)

Moradi, Christopher P.; Douberly, Gary E., E-mail: douberly@uga.edu [Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556 (United States); Xie, Changjian; Guo, Hua [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Kaufmann, Matin [Department of Physical Chemistry II, Ruhr-University Bochum, D-44801 Bochum (Germany)

2016-04-28

Pyrolytic dissociation of Cl{sub 2} is employed to dope helium droplets with single Cl atoms. Sequential addition of NH{sub 3} to Cl-doped droplets leads to the formation of a complex residing in the entry valley to the substitution reaction Cl + NH{sub 3} → ClNH{sub 2} + H. Infrared Stark spectroscopy in the NH stretching region reveals symmetric and antisymmetric vibrations of a C{sub 3v} symmetric top. Frequency shifts from NH{sub 3} and dipole moment measurements are consistent with a ClNH{sub 3} complex containing a relatively strong two-center three-electron (2c–3e) bond. The nature of the 2c–3e bonding in ClNH{sub 3} is explored computationally and found to be consistent with the complexation-induced blue shifts observed experimentally. Computations of interconversion pathways reveal nearly barrierless routes to the formation of this complex, consistent with the absence in experimental spectra of two other complexes, NH{sub 3}Cl and Cl–HNH{sub 2}, which are predicted in the entry valley to the hydrogen abstraction reaction Cl + NH{sub 3} → HCl + NH{sub 2}.

Early-transition-metal ketenimine complexes. Synthesis, reactivity, and structural characterization of complexes with. eta. sup 2 (C,N)-ketenimine groups bound to the halogenobis((trimethylsilyl)cyclopentadienyl)niobium unit. X-ray structure of Nb(. eta. sup 5 -C sub 5 H sub 4 SiMe sub 3 ) sub 2 Cl(. eta. sup 2 (C,N)-PhN double bond C double bond CPh sub 2 )

Energy Technology Data Exchange (ETDEWEB)

Antinolo, A.; Fajardo, M.; Lopez Mardomingo, C.; Otero, A. (Univ. de Alcala de Henares (Spain)); Mourad, Y.; Mugnier, Y. (Centre National de la Recherche Scientifique, Dijon (France)); Sanz-Aparicio, J.; Fonseca, I.; Florencio, F. (CSIC, Madrid (Spain))

1990-11-01

The reaction of Nb({eta}{sup 5}-C{sub 5}H{sub 4}SiMe{sub 3}){sub 2}X (X = Cl, Br) with 1 equiv of various ketenimines, R{sup 1}N{double bond}C{double bond}CR{sup 2}R{sup 3}, leads to the niobium derivatives Nb({eta}{sup 5}-C{sub 5}H{sub 4}SiMe{sub 3}){sub 2}X({eta}{sup 2}(C,N)-R{sup 1}N{double bond}C{double bond}CR{sup 2}R{sup 3}) (1, X = Cl, R{sup 1} = R{sup 2} = R{sup 3} = C{sub 6}H{sub 5}; 2, X = Cl, R{sup 1} = p-CH{sub 3}-C{sub 6}H{sub 4}, R{sup 2} = R{sup 3} = C{sub 6}H{sub 5}; 3, X = Br, R{sup 1} = R{sup 2} = R{sup 3} = C{sub 6}H{sub 5}; 4, X = Br, R{sup 1} = p-CH{sub 3}-C{sub 6}H{sub 4}, R{sup 2} = R{sup 3} = C{sub 6}H{sub 5}; 5, X = Cl, R{sup 1} = R{sup 2} = C{sub 6}H{sub 5}, R{sup 3} = CH{sub 3}; 6, X = Br, R{sup 1} = R{sup 2} = C{sub 6}H{sub 5}, R{sup 3} = CH{sub 3}) with the expected ketenimine C{double bond}N bonding mode. Reduction of 1 with 1 equiv of Na/Hg gives the complex Nb({eta}{sup 5}-C{sub 5}H{sub 4}SiMe{sub 3}){sub 2}({eta}{sup 2}(C,N)-PhN{double bond}C{double bond}CPh{sub 2}) (9) as a paramagnetic compound. The reduction of 9 with 1 equiv of Na/Hg and the subsequent addition of a proton source (ethanol) leads to the iminoacyl compound Nb({eta}{sup 5}-C{sub 5}H{sub 4}SiMe{sub 3}){sub 2}(CRNR{sup 1}) (10, R = CH(Ph{sub 2}), R{sup 1} = Ph). The one- and two-electron reductions of 1 have been studied by cyclic voltammetry experiments. The structure of 1 was determined by single-crystal X-ray diffractometry: a = 24.4904 (14) {angstrom}, b = 11.0435 (04) {angstrom}, c = 26.6130 (15) {angstrom}, {beta} = 109.890 (5){degree}, monoclinic, space group C2/c, Z = 8, V = 6,768.4 (5) {angstrom}{sup 3}, {rho}{sub calcd} = 1.3194 g/mL, R = 0.048, R{sub w} = 0.060 based on 4,806 observed reflections. The structure contains a niobium atom bonded to two cyclopentadienyl rings in a {eta}{sup 5} fashion; the coordination of the metal is completed by a Cl atom and a {eta}{sup 2}(C,N)-bonded ketenimine ligand.

Complex cubic metallides AM{sub ∝6} (A=Ca, Sr; M=Zn, Cd, Hg). Synthesis, crystal chemistry and chemical bonding

Energy Technology Data Exchange (ETDEWEB)

Schwarz, Michael; Wendorff, Marco; Roehr, Caroline [Freiburg Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

2017-09-01

In a systematic synthetic, crystallographic and bond theoretical study, the stability ranges as well as the distribution of the isoelectronic late d-block elements Zn, Cd and Hg (M) in the polyanions of the YCd{sub 6}-type phases (Ca/Sr)Cd{sub 6} have been investigated. Starting from Ca(Cd/Hg){sub 6}, 12-30% of the M atoms can be substituted by Zn, which gradually occupies the center of the empty cubes. In all ternary compounds, smaller/less electronegative Zn/Cd atoms occupy the disordered tetrahedra explaining the lack of the YCd{sub 6}-type for pure mercurides. Along the section SrCd{sub 6}-SrHg{sub 6}, the ordered Eu{sub 4}Cd{sub 25}-type is formed (Sr{sub 4}Cd{sub 16.1}Hg{sub 8.9}: cF1392, Fd anti 3, a=3191.93(5) pm, R1=0.0404). Besides, two new complex cubic Ca phases appear at increased Zn proportion: Ca{sub 2}Zn{sub 5.1}Cd{sub 5.8}, which exhibits a nearly complete site preference of Zn and Cd, crystallizes in the rare cubic Mg{sub 2}Zn{sub 11}-type structure (cP39-δ, Pm anti 3, a=918.1(1) pm, R1=0.0349). In the Ca-Hg system, an increased Zn proportion yielded the new compound CaZn{sub 1.31}Hg{sub 3.69} (cF480, F anti 43m, a=2145.43(9) pm, R1=0.0572), with a complex cubic structure closely related to Ba{sub 20}Hg{sub 103}. All structures, which are commonly described using nested polyhedra around high-symmetric sites, are alternatively described in accordance with the calculated electron densities and charge distribution: building blocks are face-sharing [M{sub 4}] tetrahedra (star polyhedra such as TS, IS, OS), each with a cage-critical point in its center, and [M{sub 8}] cubes (deformed TS), which are either empty, distorted or filled. The M element distribution in the anion is determined by size criteria and the difference in electronegativity, which induces a preferred formation of heteroatomic polar bonds.

What is the best bonding model of the (σ-H-BR) species bound to a transition metal? Bonding analysis in complexes [(H)2Cl(PMe3)2M(σ-H-BR)] (M = Fe, Ru, Os).

Science.gov (United States)

Pandey, Krishna K

2012-03-21

Density Functional Theory calculations have been performed for the σ-hydroboryl complexes of iron, ruthenium and osmium [(H)(2)Cl(PMe(3))(2)M(σ-H-BR)] (M = Fe, Ru, Os; R = OMe, NMe(2), Ph) at the BP86/TZ2P/ZORA level of theory in order to understand the interactions between metal and HBR ligands. The calculated geometries of the complexes [(H)(2)Cl(PMe(3))(2)Ru(HBNMe(2))], [(H)(2)Cl(PMe(3))(2)Os(HBR)] (R = OMe, NMe(2)) are in excellent agreement with structurally characterized complexes [(H)(2)Cl(P(i)Pr(3))(2)Os(σ-H-BNMe(2))], [(H)(2)Cl(P(i)Pr(3))(2)Os{σ-H-BOCH(2)CH(2)OB(O(2)CH(2)CH(2))}] and [(H)(2)Cl(P(i)Pr(3))(2)Os(σ-H-BNMe(2))]. The longer calculated M-B bond distance in complex [(H)(2)Cl(PMe(3))(2)M(σ-H-BNMe(2))] are due to greater B-N π bonding and as a result, a weaker M-B π-back-bonding. The B-H2 bond distances reveal that (i) iron complexes contain bis(σ-borane) ligand, (ii) ruthenium complexes contain (σ-H-BR) ligands with a stretched B-H2 bond, and (iii) osmium complexes contain hydride (H2) and (σ-H-BR) ligands. The H-BR ligands in osmium complexes are a better trans-directing ligand than the Cl ligand. Values of interaction energy, electrostatic interaction, orbital interaction, and bond dissociation energy for interactions between ionic fragments are very large and may not be consistent with M-(σ-H-BR) bonding. The EDA as well as NBO and AIM analysis suggest that the best bonding model for the M-σ-H-BR interactions in the complexes [(H)(2)Cl(PMe(3))(2)M(σ-H-BR)] is the interaction between neutral fragments [(H)(2)Cl(PMe(3))(2)M] and [σ-H-BR]. This becomes evident from the calculated values for the orbital interactions. The electron configuration of the fragments which is shown for C in Fig. 1 experiences the smallest change upon the M-σ-H-BR bond formation. Since model C also requires the least amount of electronic excitation and geometry changes of all models given by the ΔE(prep) values, it is clearly the most appropriate choice of

Recognition of a novel type X═N-Hal···Hal (X = C, S, P; Hal = F, Cl, Br, I) halogen bonding.

Science.gov (United States)

Gushchin, Pavel V; Kuznetsov, Maxim L; Haukka, Matti; Kukushkin, Vadim Yu

2013-04-04

The chlorination of the eight-membered platinum(II) chelates [PtCl2{NH═C(NR2)N(Ph)C(═NH)N(Ph)C(NR2)═NH}] (R = Me (1); R2 = (CH2)5 (2)) with uncomplexed imino group with Cl2 gives complexes bearing the ═N-Cl moiety [PtCl4{NH═C(NR2)N(Ph)C(═NCl)N(Ph)C(NR2)═NH}] (R = Me (3); R2 = (CH2)5 (4)). X-ray study for 3 revealed a novel type intermolecular halogen bonding ═N-Cl···Cl(-), formed between the Cl atom of the chlorinated imine and the chloride bound to the platinum(IV) center. The processing relevant structural data retrieved from the Cambridge Structural Database (CSDB) shows that this type of halogen bonding is realized in 18 more molecular species having X═N-Hal moieties (X = C, P, S, V, W; Hal = Cl, Br, I), but this weak ═N-Hal···Hal(-) bonding was totally neglected in the previous works. The presence of the halogen bonding in 3 was confirmed by theoretical calculations at the density functional theory (DFT, M06-2X) level, and its nature was analyzed.

Group 13 ligand supported heavy-metal complexes: first structural evidence for gallium-lead and gallium-mercury bonds.

Science.gov (United States)

Prabusankar, Ganesan; Gemel, Christian; Winter, Manuela; Seidel, Rüdiger W; Fischer, Roland A

2010-05-25

Heavy-metal complexes of lead and mercury stabilized by Group 13 ligands were derived from the oxidative addition of Ga(ddp) (ddp=HC(CMeNC(6)H(3)-2,6-iPr(2))(2), 2-diisopropylphenylamino-4-diisopropyl phenylimino-2-pentene) with corresponding metal precursors. The reaction of Me(3)PbCl and Ga(ddp) afforded compound [{(ddp)Ga(Cl)}PbMe(3)] (1) composed of Ga-Pb(IV) bonds. In addition, the monomeric plumbylene-type compound [{(ddp)Ga(OSO(2)CF(3))}(2)Pb(thf)] (2a) with an unsupported Ga-Pb(II)-Ga linkage was obtained by the reaction of [Pb(OSO(2)CF(3))(3)] with Ga(ddp) (2 equiv). Compound 2a falls under the rare example of a discrete plumbylene-type compound supported by a nonclassical ligand. Interesting structural changes were observed when [Pb(OSO(2)CF(3))(3)]2.H(2)O was treated with Ga(ddp) in a 1:2 ratio to yield [{(ddp)Ga(mu-OSO(2)CF(3))}(2)(OH(2))Pb] (2b) at below -10 degrees C. Compound 2b consists of a bent Ga-Pb-Ga backbone with a bridging triflate group between the Ga-Pb bond and a weakly interacting water molecule at the gallium center. Similarly, the reaction of mercury thiolate Hg(SC(6)F(5)) with Ga(ddp) (2 equiv) produced the bimetallic homoleptic compounds anti-[{(ddp)Ga(SC(6)F(5))}(2)Hg] (3a) and gauche-[{(ddp)Ga(SC(6)F(5))}(2)Hg] (3b), respectively, with a linear Ga-Hg-Ga linkage. Compounds 1-3 were structurally characterized and these are the first examples of compounds comprised of Ga-Pb(II), Ga-Pb(IV), and Ga-Hg bonds.

Inhibition of EBV-mediated membrane fusion by anti-gHgL antibodies

Energy Technology Data Exchange (ETDEWEB)

Sathiyamoorthy, Karthik; Jiang, Jiansen; Möhl, Britta S.; Chen, Jia; Zhou, Z. Hong; Longnecker, Richard; Jardetzky, Theodore S. (UCLA); (Stanford-MED); (NWU)

2017-09-22

Herpesvirus entry into cells requires the coordinated action of multiple virus envelope glycoproteins, including gH, gL, and gB. For EBV, the gp42 protein assembles into complexes with gHgL heterodimers and binds HLA class II to activate gB-mediated membrane fusion with B cells. EBV tropism is dictated by gp42 levels in the virion, as it inhibits entry into epithelial cells while promoting entry into B cells. The gHgL and gB proteins are targets of neutralizing antibodies and potential candidates for subunit vaccine development, but our understanding of their neutralizing epitopes and the mechanisms of inhibition remain relatively unexplored. Here we studied the structures and mechanisms of two anti-gHgL antibodies, CL40 and CL59, that block membrane fusion with both B cells and epithelial cells. We determined the structures of the CL40 and CL59 complexes with gHgL using X-ray crystallography and EM to identify their epitope locations. CL59 binds to the C-terminal domain IV of gH, while CL40 binds to a site occupied by the gp42 receptor binding domain. CL40 binding to gHgL/gp42 complexes is not blocked by gp42 and does not interfere with gp42 binding to HLA class II, indicating that its ability to block membrane fusion with B cells represents a defect in gB activation. These data indicate that anti-gHgL neutralizing antibodies can block gHgL-mediated activation of gB through different surface epitopes and mechanisms.

Injury of Hg2+ and DBS on Lemna minor%Hg2+、DBS对浮萍的伤害研究

Institute of Scientific and Technical Information of China (English)

马剑敏; 王琳; 杜晋立; 吴晶敏

2001-01-01

The injury degree of Lemna minor by the stress of Hg2+ and DBSare reported.The concentrations of chlorophyll and dissolved protein decrease with the increase of Hg2+ and DBS concentrations or as treatment time is continued,dead percentage increase with the increase of Hg2+ and DBS concentrations or as treatment time is continued.When the concentrations of HgCl2 is 6mg/L or DBS is 12mg/L,about 70% of Lemna minor can live for 10 days at least.%研究了在Hg2+、DBS胁迫下，浮萍(LemnaminorL.)植株的枯死率、叶绿素含量和可溶性蛋白质含量的变化。植株的枯死率随Hg2+、DBS浓度升高和处理时间的延长而增加；叶绿素和蛋白质含量随Hg2+和DBS浓度升高和处理时间的延长而逐渐下降。在HgCl2、DBS浓度分别为6mg/L、12mg/L时，约70%的浮萍10d内仍存活。

Enhanced Hg{sup 2+} removal and Hg{sup 0} re-emission control from wet fuel gas desulfurization liquors with additives

Energy Technology Data Exchange (ETDEWEB)

Tingmei Tang; Jiang Xu; Rongjie Lu; Jingjing Wo; Xinhua Xu [Zhejiang University, Hangzhou (China). Department of Environmental Engineering

2010-12-15

Secondary atmospheric pollutions may result from wet flue gas desulfurization (FGD) systems caused by the reduction of Hg{sup 2+} to Hg{sup 0}. The present study employed three agents: Na{sub 2}S, 2,4,6-trimercaptotiazine, trisodium salt nonahydrate (TMT) and sodium dithiocarbamate (DTCR) to precipitate aqueous Hg{sup 2+} in simulated desulfurization solutions. The effects of the precipitator's dosing quantity, the initial pH value, the reaction temperature, the concentrations of Cl{sup -} and other metal ions (e.g. Cu{sup 2+} and Pb{sup 2+}) on Hg{sup 2+} removal were studied. A linear relationship was observed between Hg{sup 2+} removal efficiency and the increasing precipitator's doses along with initial pH. The addition of chloride and metal ions impaired the Hg{sup 2+} removal from solutions due to the complexation of Cl{sup -} and Hg{sup 2+} as well as the chelating competition between Hg{sup 2+} and other metal ions. Based on a comprehensive comparison of the treatment effects, DTCR was found to be the most effective precipitating agent. Moreover, all the precipitating agents were potent enough to inhibit Hg{sup 2+} reduction as well as Hg{sup 0} re-emission from FGD liquors. More than 90% Hg{sup 2+} was captured by precipitating agents while Hg{sup 2+} reduction efficiency decreased from 54% to just less than 3%. The additives could efficiently control the secondary Hg{sup 0} pollution from FGD liquors. 21 refs., 6 figs.

Comparing and interpreting laboratory results of Hg oxidation by a chlorine species

International Nuclear Information System (INIS)

Agarwal, Hans; Romero, Carlos E.; Stenger, Harvey G.

2007-01-01

Several researchers have performed experimental work in attempts to explain the effects of various flue-gas components on the oxidation of elemental mercury (Hg 0 ). Some have concluded that water (H 2 O) inhibits Hg oxidation by chlorine (Cl 2 ). In recently published work, it was found that sulfur dioxide (SO 2 ) and nitric oxide (NO) also have an inhibitory effect on Hg oxidation. This paper aims to serve three purposes. First, to present data obtained in a laboratory scale apparatus, designed to test the effects of Cl 2 on the oxidation of Hg 0 with respect to temperature. The results show that as temperature increases, Cl 2 is less effective as an Hg oxidizing agent. Second, this paper presents a consolidation of data taken from several sources, where the effects of various flue-gas components on the oxidation of Hg 0 is observed and discussed. The summary of these results shows the following general trends: at high temperatures, hydrogen chloride (HCl) is the primary chlorine species responsible for Hg 0 oxidation, while at lower temperatures, Cl 2 is the dominant species. Third, a simple two reaction model is suggested to predict the experimental data shown in this paper. The results show that the predicted percent Hg oxidation values correspond very well with the observed experimental values

Structure cristalline du composé Hg3-xSbx(S+Se2+xI2-x (x ≃ 0.1

Directory of Open Access Journals (Sweden)

Mohammed Kars

2016-03-01

Full Text Available Single crystals of the mercury chalcohalide Hg3-xSbx(S+Se2+xI2-x (x ≃ 0.1 (mercury antimony sulfide selenide iodide, were grown by a chemical transport reaction. The structure contains three independent A (Hg/Sb atoms; each atom is strongly covalently bonded with two X (Se/S atoms to form approximately linear X–A–X units. The X–A–X units link to form A4X4 rings, which are combined into infinite crankshaft-type bands running along the [100] direction. Four equatorial E (I/X = Se,S atoms at relatively long distances complete the distorted octahedral coordination of A (Hg/Sb. The crystal under investigation was twinned by non-merohedry with a refined twin domain fraction of 0.814 (6:0.186 (6. The structure is isotypic with Hg3Se2I2 [Beck & Hedderich (2000. J. Solid State Chem. 151, 73–76], but the current determination reveals a coupled substitution, with partial replacement of Hg+2 by Sb+3, balanced by the equivalent substitution of I−1 by S−2 and Se−2. Bond-valence calculations are consistent with this relative substitution model.

Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) by hydrolyzed acrylamide-grafted PET films.

Science.gov (United States)

Rahman, Nazia; Sato, Nobuhiro; Sugiyama, Masaaki; Hidaka, Yoshiki; Okabe, Hirotaka; Hara, Kazuhiro

2014-01-01

Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) using hydrolyzed acrylamide (AAm)-grafted polyethylene terephthalate (PET) films was examined to explore the potential reuse of waste PET materials. Selective recovery of Hg(II) from a mixture of soft acids with similar structure, such as Hg(II) and Pb(II), is important to allow the reuse of recovered Hg(II). An adsorbent for selective Hg(II) adsorption was prepared by γ-ray-induced grafting of AAm onto PET films followed by partial hydrolysis through KOH treatment. The adsorption capacity of the AAm-grafted PET films for Hg(II) ions increased from 15 to 70 mg/g after partial hydrolysis because of the reduction of hydrogen bonding between -CONH2 groups and the corresponding improved access of metal ions to the amide groups. The prepared adsorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The absorbent film showed high selectivity for the adsorption of Hg(II) over Pb(II) throughout the entire initial metal concentration range (100-500 mg/L) and pH range (2.2-5.6) studied. The high selectivity is attributed to the ability of Hg(II) ions to form covalent bonds with the amide groups. The calculated selectivity coefficient for the adsorbent binding Hg(II) over Pb(II) was 19.2 at pH 4.5 with an initial metal concentration of 100 mg/L. Selective Hg(II) adsorption equilibrium data followed the Langmuir model and kinetic data were well fitted by a pseudo-second-order equation. The adsorbed Hg(II) and Pb(II) ions were effectively desorbed from the adsorbent film by acid treatment, and the regenerated film showed no marked loss of adsorption capacity upon reuse for selective Hg(II) adsorption.

The new barium zinc mercurides Ba3ZnHg10 and BaZn0.6Hg3.4 – Synthesis, crystal and electronic structure

International Nuclear Information System (INIS)

Schwarz, Michael; Wendorff, Marco; Röhr, Caroline

2012-01-01

The title compounds Ba 3 ZnHg 10 and BaZn 0.6 Hg 3.4 were synthesized from stoichiometric ratios of the elements in Ta crucibles. Their crystal structures, which both represent new structure types, have been determined using single crystal X-ray data. The structure of Ba 3 ZnHg 10 (orthorhombic, oP28, space group Pmmn, a=701.2(3), b=1706.9(8), c=627.3(3)pm, Z=2, R1=0.0657) contains folded 4 4 Hg nets, where the meshes form the bases of flat rectangular pyramids resembling the structure of BaAl 4 . The flat pyramids are connected via Hg–Zn/Hg bonds, leaving large channels at the folds, in which Ba(1) and Hg(2) atoms alternate. Whereas the remaining Hg/Zn atoms form a covalent 3D network of three- to five-bonded atoms with short M–M distances (273–301 pm; CN 9–11), the Hg(2) atoms in the channels adopt a comparatively large coordination number of 12 and increased distances (317–348 pm) to their Zn/Hg neighbours. In the structure of BaZn 0.6 Hg 3.4 (cubic, cI320, space group I4 ¯ 3d, a=2025.50(7) pm, Z=64, R1=0.0440), with a chemical composition not much different from that of Ba 3 ZnHg 10 , the Zn/Hg atoms of the mixed positions M(1/2) are arranged in an slightly distorted primitive cubic lattice with a 4×4×4 subcell relation to the unit cell. The 24 of the originating 64 cubes contain planar cis tetramers Hg(5,6) 4 with Hg in a nearly trigonal planar or tetrahedral coordination. In another 24 of the small cubes, two opposing faces are decorated by Hg(3,4) 2 dumbbells, two by Ba(2) atoms respectively. The third type of small cubes are centered by Ba(1) atoms only. The complex 3D polyanionic Hg/Zn network thus formed is compared with the Hg partial structure in Rb 3 Hg 20 applying a group-subgroup relation. Despite their different overall structures, the connectivity of the negatively charged Hg atoms, the rather metallic Zn bonding characteristic (as obtained from FP-LAPW band structure calculations) and the coordination number of 16 for all Ba cations

An enzyme-linked immunosorbent assay (ELISA) for quantification of human collectin 11 (CL-11, CL-K1)

DEFF Research Database (Denmark)

Selman, L; Henriksen, M L; Brandt, J

2012-01-01

-associated serine protease 1 (MASP-1) and/or MASP-3 in circulation. Mutation in the CL-11 gene was recently associated with the developmental syndrome 3MC. In the present study, we established and thoroughly validated a sandwich enzyme-linked immunosorbent assay (ELISA) based on two different monoclonal antibodies....... The assay is highly sensitive, specific and shows excellent quantitative characteristics such as reproducibility, dilution linearity and recovery (97.7-104%). The working range is 0.15-34 ng/ml. The CL-11 concentration in two CL-11-deficient individuals affected by the 3MC syndrome was determined...... and thawing to a certain extent did not influence the ELISA. This ELISA offers a convenient and reliable method for studying CL-11 levels in relation to a variety of human diseases and syndromes....

Influence of Th(NO3)4, KCl and pH on the reduction of HgCl2 under X- and UV-radiations

International Nuclear Information System (INIS)

Prashad, Jagdish; Suri, Ranjana

2000-01-01

The yield of Hg 2 Cl 2 is maximum at relatively high pH, diminished progressively with decrease of pH and is completely inhibited beyond a critical pH. In the presence of Th(NO 3 ) 4 , slight reduction is observed. The results are explicable by assuming the existence of hydrated molecular ion H 2 + (hydr.). (author)

Liquid-vapor equilibrium in LaCl3-LuCl3 and PrCl3-NdCl3 systems

International Nuclear Information System (INIS)

Nisel'son, L.A.; Lyzlov, Yu.N.; Solov'ev, S.I.

1978-01-01

The liquid-vapour equilibrium in the systems LaCl 3 -LuCl 3 and PrCl 3 -NdCl 3 was studied by the boiling-point method. It was established that the system LaCl 3 -LuCl 3 is near-ideal. In the PrCl 3 -NdCl 3 system, a considerable positive deviation from the ideal with the formation of an azeotrope was detected. The azeotrope has a ''smeared-out'' minimum, which falls on a mixture containing approximately 65 mol.% neodymium trichloride. The boiling point of this mixture at a pressure of 1 mm Hg is approximately 975 deg C. The relative volatility coefficients in both systems were studied by the Raleigh distillation method. The presence of the azeotrope in the system PrCl 3 -NdCl 3 is confirmed by the nature of the dependence of the relative volatility coefficient on the composition of the mixture

Immobilization of Hg(II) by Coprecipitation in Sulfate-Cement Systems

Science.gov (United States)

2012-01-01

Uptake and molecular speciation of dissolved Hg during formation of Al- or Fe-ettringite-type and high-pH phases were investigated in coprecipitation and sorption experiments of sulfate-cement treatments used for soil and sediment remediation. Ettringite and minor gypsum were identified by XRD as primary phases in Al systems, whereas gypsum and ferrihydrite were the main products in Hg–Fe precipitates. Characterization of Hg–Al solids by bulk Hg EXAFS, electron microprobe, and microfocused-XRF mapping indicated coordination of Hg by Cl ligands, multiple Hg and Cl backscattering atoms, and concentration of Hg as small particles. Thermodynamic predictions agreed with experimental observations for bulk phases, but Hg speciation indicated lack of equilibration with the final solution. Results suggest physical encapsulation of Hg as a polynuclear chloromercury(II) salt in ettringite as the primary immobilization mechanism. In Hg–Fe solids, structural characterization indicated Hg coordination by O atoms only and Fe backscattering atoms that is consistent with inner-sphere complexation of Hg(OH)20 coprecipitated with ferrihydrite. Precipitation of ferrihydrite removed Hg from solution, but the resulting solid was sufficiently hydrated to allow equilibration of sorbed Hg species with the aqueous solution. Electron microprobe XRF characterization of sorption samples with low Hg concentration reacted with cement and FeSO4 amendment indicated correlation of Hg and Fe, supporting the interpretation of Hg removal by precipitation of an Fe(III) oxide phase. PMID:22594782

Quantum mechanical study on hydrogen bonds between 3-aminophenol and CH{sub x}Cl{sub 4-}x (x=1, 2, 3): Effect of the number of halogen atoms

Energy Technology Data Exchange (ETDEWEB)

Lee, So Young; Kang, Hyuk [Dept. of Chemistry, Ajou University, Suwon (Korea, Republic of)

2015-03-15

Hydrogen bonds between 3-aminophenol and three chlorine-substituted methanes (CHCl{sub 3}, CH{sub 2}Cl{sub 2}, and CH{sub 3}Cl) were quantum mechanically studied at MP2/aug-cc-pVDZ level. Several low-energy structures with a hydrogen bond were identified for all chlorinated methanes, and the properties of their C[BOND]H stretching vibrations were investigated. When it is hydrogen-bonded to 3-aminophenol (3AP), the C[BOND]H stretching frequency of CHCl{sub 3} is blue-shifted by 18–54 cm−1, and its IR absorption intensity is 48–74 times increased, depending on the isomer. The symmetric and antisymmetric C[BOND]H stretches of CH{sub 2}Cl{sub 2} and CH{sub 3}Cl are shifted in either direction by a few cm−1 upon hydrogen-bonding to 3AP, and their IR intensity was increased by a few times. It is concluded that all chlorinated methanes can make a π-hydrogen bond to 3AP but only CHCl{sub 3}, the one with the most chlorine atoms, makes a blue-shifting hydrogen bond, or an “antihydrogen bond”.

Stoichiometry and local bond configuration of In{sub 2}S{sub 3}:Cl thin films by Rutherford backscattering spectrometry

Energy Technology Data Exchange (ETDEWEB)

Juma, Albert O., E-mail: jumaa@biust.ac.bw

2016-10-15

In{sub 2}S{sub 3} thin films deposited using chemical methods always contain residual elements from the precursors, which modify their properties. As buffer layers in solar cells, the residual elements in the In{sub 2}S{sub 3} layer affect the performance of these devices. The stoichiometry of In{sub 2}S{sub 3} thin films deposited by spray ion layer gas reaction (ILGAR) was studied as a function of the residual Cl from InCl{sub 3} precursor by varying the deposition parameters. The chemical formula was deduced from the elemental composition determined using Rutherford backscattering (RBS). Incomplete sulfurization of the precursor implies that residual Cl{sup −} remains bonded to the In{sup 3+} ions while some occupy interstitial and/or antisite positions in the In{sub 2}S{sub 3} matrix. This results in thin films with different stoichiometry, described by the formula In{sub 4}S{sub 6−x}Cl{sub 2x+2y}. This changes the local bond configuration and geometry and underpins the influence of residual Cl on the physical properties of In{sub 2}S{sub 3} thin films.

Characterization of Na+-linked and Na+-independent Cl-/HCO3- exchange systems in Chinese hamster lung fibroblasts

International Nuclear Information System (INIS)

Cassel, D.; Scharf, O.; Rotman, M.; Cragoe, E.J. Jr.; Katz, M.

1988-01-01

The PS120 variant of Chinese hamster lung fibroblasts which lacks Na + /H + exchange activity was used to investigate bicarbonate transport systems and their role in intracellular pH (pH/sub i/) regulation. When pH/sub i/ was decreased by acid load, bicarbonate caused pH/sub i/ increase and stimulated 36 Cl - efflux from the cells, both in a Na + -dependent manner. These results together with previous findings that bicarbonate stimulates 22 Na + uptake in PS120 cells demonstrate the presence of a Na + -linked Cl - /HCO 3 - exchange system. In cells with normal initial pH/sub i/, bicarbonate caused Na + -independent pH/sub i/ increase in Cl - -free solutions and stimulated Na + -independent 36 Cl - efflux, indicating that a Na + -independent Cl - /HCO 3 - exchanger is also present in the cell. Na + -linked and Na + -independent Cl - /HCO 3- exchange is apparently mediated by two distinct systems, since a [(tetrahydrofluorene-7-yl)oxy]acetic acid derivative selectively inhibits the Na + -independent exchanger. An additional distinctive features is a 10-fold lower affinity for chloride of the Na + -linked exchanger. The Na + -linked and Na + -independent Cl - /HCO 3 - exchange systems are likely to protect the cell from acid and alkaline load, respectively

An enzyme-linked immunosorbent assay (ELISA) for quantification of human collectin 11 (CL-11, CL-K1)

Science.gov (United States)

Selman, L.; Henriksen, M.L.; Brandt, J.; Palarasah, Y.; Waters, A.; Beales, P.L.; Holmskov, U.; Jørgensen, T.J.D.; Nielsen, C.; Skjodt, K.; Hansen, S.

2012-01-01

Collectin 11 (CL-11), also referred to as collectin kidney 1 (CL-K1), is a pattern recognition molecule that belongs to the collectin group of proteins involved in innate immunity. It interacts with glycoconjugates on pathogen surfaces and has been found in complex with mannose-binding lectin-associated serine protease 1 (MASP-1) and/or MASP-3 in circulation. Mutation in the CL-11 gene was recently associated with the developmental syndrome 3MC. In the present study, we established and thoroughly validated a sandwich enzyme-linked immunosorbent assay (ELISA) based on two different monoclonal antibodies. The assay is highly sensitive, specific and shows excellent quantitative characteristics such as reproducibility, dilution linearity and recovery (97.7–104%). The working range is 0.15–34 ng/ml. The CL-11 concentration in two CL-11-deficient individuals affected by the 3MC syndrome was determined to be below 2.1 ng/ml. We measured the mean serum CL-11 concentration to 284 ng/ml in 100 Danish blood donors, with a 95% confidence interval of 269–299 ng/ml. There was no significant difference in the CL-11 concentration measured in matched serum and plasma samples. Storage of samples and repeated freezing and thawing to a certain extent did not influence the ELISA. This ELISA offers a convenient and reliable method for studying CL-11 levels in relation to a variety of human diseases and syndromes. PMID:22301270

The new barium mercuride BaHg6 and ternary indium and gallium derivatives

International Nuclear Information System (INIS)

Wendorff, Marco; Röhr, Caroline

2013-01-01

Highlights: ► The new binary Hg-rich mercuride BaHg 6 crystallizes with a singular structure type. ► Ternary In substituted compounds are isotypic, whereas Ga substituted compounds are only structurally related. ► Structure relation to other Hg-rich alkali and alkaline earth mercurides. ► Discussion of covalent and metallic bonding aspects, as found by structure features and band structure calculations. - Abstract: The new binary barium mercuride BaHg 6 and the derived ternary indium and gallium containing compounds BaIn 1.2 Hg 4.8 and BaGa 0.8 Hg 5.2 were synthesized from melts of the elements, which were slowly cooled from 500 to 200 °C. Their crystal structures have been determined by means of single crystal X-ray diffraction. The binary mercuride BaHg 6 (Pnma, a = 1338.9(3), b = 519.39(13), c = 1042.6(4) pm, Z = 4, R1 = 0.0885) and the isotypic indium substituted compound BaIn 1.2 Hg 4.8 as well as the structurally related gallium mercuride BaGa 0.8 Hg 5.2 (Cmcm, a = 729.77(7), b = 1910.1(2), c = 507.48(5) pm, Z = 4, R1 = 0.0606) crystallize with new structure types. Common features of both structures are planar nets of five- and eight-membered Hg rings, stacked perpendicular to the shortest axes. According to their lengths, the Hg–Hg bonds can be classified into three groups: strong, short ones (I, 285–292 pm), which are only found inside the nets, and longer distances (II), still carrying bond critical points, around 300 pm. Further contacts (III) serve to complete the coordination spheres of Hg/M (320–358 pm). The overall coordination numbers of Hg/M range from 10 to 13. The Ba cations are positioned in the centers of the octagons of the Hg/M nets, thus exhibiting a 5:8:5, i.e. 18, coordination by Hg/M atoms. DFT calculations of the electronic band structure of pure BaHg 6 and ordered models of the indium ( ′ BaInHg 5 ′ ) and the gallium ( ′ BaGaHg 5 ′ ) mercurides were performed using the FP-LAPW method. The calculated Bader charges

Transition state kinetics of Hg(II) adsorption at gibbsite-water interface

International Nuclear Information System (INIS)

Weerasooriya, Rohan; Tobschall, Heinz J.; Seneviratne, Wasana; Bandara, Atula

2007-01-01

Kinetics of adsorption plays a pivotal factor in determining the bio-availability and mobility of Hg(II) in the environment. The kinetics of Hg(II) adsorption on gibbsite was examined as a function of pH, temperature and electrolyte type. Adsorption of Hg(II) was highly non-linear where the rate of Hg(II) retention was rapid initially and was followed by gradual or somewhat slow retention behavior with increasing contact time. The respective rate constants designated as k 1 (S-1: fast step) and k 2 (S-2: slow step). Always k 1 follows the order: k 1 ClO 4 >=k 1 (NO 3 ) 4 >>k 1 Cl . Such a relationship was not observed for the S-2 route. A two-step reaction model with pseudo-first order kinetics successfully described the adsorption rates of Hg(II) on gibbsite. Arrhenius and Erying models determined the thermodynamic parameters at activation states, which correspond to S-1 and S-2 routes. In a given system, always the activation energies showed a decrease with the pH. Gibbs free energy (ΔG numbersign ), enthalpy (ΔH numbersign ), and entropy (ΔS numbersign ) values of activation states were almost similar both in NaClO 4 and NaNO 3 which signal a similar Hg(II) adsorptive mechanism on gibbsite. The configurations of different Hg(II)-surface complexes were elucidated by transmission vibration spectroscopy

Solving mercury (Hg) speciation in soil samples by synchrotron X-ray microspectroscopic techniques

International Nuclear Information System (INIS)

Terzano, Roberto; Santoro, Anna; Spagnuolo, Matteo; Vekemans, Bart; Medici, Luca; Janssens, Koen; Goettlicher, Joerg; Denecke, Melissa A.; Mangold, Stefan; Ruggiero, Pacifico

2010-01-01

Direct mercury (Hg) speciation was assessed for soil samples with a Hg concentration ranging from 7 up to 240 mg kg -1 . Hg chemical forms were identified and quantified by sequential extractions and bulk- and micro-analytical techniques exploiting synchrotron generated X-rays. In particular, microspectroscopic techniques such as μ-XRF, μ-XRD and μ-XANES were necessary to solve bulk Hg speciation, in both soil fractions 3 S 2 Cl 2 ), and an amorphous phase containing Hg bound to chlorine and sulfur. The amount of metacinnabar and amorphous phases increased in the fraction <2 μm. No interaction among Hg-species and soil components was observed. All the observed Hg-species originated from the slow weathering of an inert Hg-containing waste material (K106, U.S. EPA) dumped in the area several years ago, which is changing into a relatively more dangerous source of pollution. - Direct mercury (Hg) speciation in chlor-alkali plant contaminated soils enabled the identification of potentially dangerous Hg-S/Cl amorphous species.

Brain, kidney and liver 203Hg-methyl mercury uptake in the rat: Relationship to the neutral amino acid carrier

International Nuclear Information System (INIS)

Aschner, M.

1989-01-01

To investigate the effect of L-neutral amino acids on tissue levels of methyl mercury in the adult animal, rats were infused into the external jugular vein with solutions containing a) 0.05 mM 203 Hg-MeHgCl and saline, b) 0.05 mM 203 Hg-MgHgCl-0.1 mM L-cysteine, c) 0.05 mM 203 Hg-MeHgCl-0.1 mM L-cysteine-0.1 mM L-methionine, d) 0.05 mM 203 Hg-MeHgCl-0.1 mM L-leucine, or e) 0.05 mM 203 Hg-MeHgCl-0.1 mM L-cysteine-0.1 mM L-leucine. Groups of animals were sacrificed at 3 min. 7 hr, and 96 hr. Brain, kidney, and liver 203 Hg radioactivity was measured by means of gamma-scintillation spectrometry. Brain 203 Hg concentrations L-cysteine treated animals were significantly higher compared with saline treated animals (P 203 Hg uptake (P 203 Hg concentrations were not significantly different in any of the treatment groups compared with controls, irrespective of the sacrifice time. Furthermore, the percentage of diffusible 203 Hg (non-protein bound) at each sacrifice time was not statistically different irrespective of the treatment assigned. These results suggest that methyl mercury L-cysteine conjugates in the plasma may share a common transport step with the L-neutral amino acid carrier transport system and indicate the presence in brain capillaries of a transport system capable of selectively mediating methyl mercury uptake across the capillary endothelial cell membrane. (author)

Area-based initiatives – and their work in bonding, bridging and linking social capital

DEFF Research Database (Denmark)

Agger, Annika; Jensen, Jesper Ole

2015-01-01

In this article, we provide a conceptual and argumentative framework for studying how Area-based Initiatives (ABIs) can facilitate contact between networks in deprived neighbourhoods and external forms of power (linking social capital). These relations provide the residents and other members...... of social capital (bridging, bonding and linking). The article concludes that ABIs contribute to creating linking social capital, but the extent of the contribution depends on the level of bonding and bridging social capital in the area. We argue that public planners as well as evaluators of the ABIs should...

How shared preferences in music create bonds between people: values as the missing link.

Science.gov (United States)

Boer, Diana; Fischer, Ronald; Strack, Micha; Bond, Michael H; Lo, Eva; Lam, Jason

2011-09-01

How can shared music preferences create social bonds between people? A process model is developed in which music preferences as value-expressive attitudes create social bonds via conveyed value similarity. The musical bonding model links two research streams: (a) music preferences as indicators of similarity in value orientations and (b) similarity in value orientations leading to social attraction. Two laboratory experiments and one dyadic field study demonstrated that music can create interpersonal bonds between young people because music preferences can be cues for similar or dissimilar value orientations, with similarity in values then contributing to social attraction. One study tested and ruled out an alternative explanation (via personality similarity), illuminating the differential impact of perceived value similarity versus personality similarity on social attraction. Value similarity is the missing link in explaining the musical bonding phenomenon, which seems to hold for Western and non-Western samples and in experimental and natural settings.

Theoretical evaluation on selective adsorption characteristics of alkali metal-based sorbents for gaseous oxidized mercury.

Science.gov (United States)

Tang, Hongjian; Duan, Yufeng; Zhu, Chun; Cai, Tianyi; Li, Chunfeng; Cai, Liang

2017-10-01

Alkali metal-based sorbents are potential for oxidized mercury (Hg 2+ ) selective adsorption but show hardly effect to elemental mercury (Hg 0 ) in flue gas. Density functional theory (DFT) was employed to investigate the Hg 0 and HgCl 2 adsorption mechanism over alkali metal-based sorbents, including calcium oxide (CaO), magnesium oxide (MgO), potassium chloride (KCl) and sodium chloride (NaCl). Hg 0 was found to weakly interact with CaO (001), MgO (001), KCl (001) and NaCl (001) surfaces while HgCl 2 was effectively adsorbed on top-O and top-Cl sites. Charge transfer and bond population were calculated to discuss the covalency and ionicity of HgCl 2 bonding with the adsorption sites. The partial density of states (PDOS) analysis manifests that HgCl 2 strongly interacts with surface sites through the orbital hybridizations between Hg and top O or Cl. Frontier molecular orbital (FMO) energy and Mulliken electronegativity are introduced as the quantitative criteria to evaluate the reactivity of mercury species and alkali metal-based sorbents. HgCl 2 is identified as a Lewis acid and more reactive than Hg 0 . The Lewis basicity of the four alkali metal-based sorbents is predicted as the increasing order: NaCl < MgO < KCl < CaO, in consistence with the trend of HgCl 2 adsorption energies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cytotoxicity of dental composite (co)monomers and the amalgam component Hg{sup 2+} in human gingival fibroblasts

Energy Technology Data Exchange (ETDEWEB)

Reichl, Franz-Xaver; Simon, Sabine; Esters, Magalie; Seiss, Mario [Ludwig-Maximilians-University of Munich, Walther-Straub-Institute of Pharmacology and Toxicology, Munich (Germany); Kehe, Kai [Bundeswehr Institute of Pharmacology and Toxicology, Munich (Germany); Kleinsasser, Norbert [University of Regensburg, Department of Otolaryngology - Head and Neck Surgery, Regensburg (Germany); Hickel, Reinhard [Ludwig-Maximilians-University, Department of Operative Dentistry and Periodontology, Munich (Germany)

2006-08-15

Unpolymerized resin (co)monomers or mercury (Hg) can be released from restorative dental materials (e.g. composites and amalgam). They can diffuse into the tooth pulp or the gingiva. They can also reach the gingiva and organs by the circulating blood after the uptake from swallowed saliva. The cytotoxicity of dental composite components hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and bisglycidylmethacrylate (Bis-GMA) as well as the amalgam component Hg{sup 2+} (as HgCl{sub 2}) and methyl mercury chloride (MeHgCl) was investigated on human gingival fibroblasts (HGFs) at two time intervals. To test the cytotoxicity of substances, the bromodeoxyuridine (BrdU) assay and the lactate dehydrogenase (LDH) assay were used. The test substances were added in various concentrations and cells were incubated for 24 or 48 h. The EC{sub 50} values were obtained as half-maximum-effect concentrations from fitted curves. Following EC{sub 50} values were found [BrdU: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 8.860 (0.440)/6.600(0.630), TEGDMA 1.810(0.130)/1.220(0.130), UDMA 0.120(0.010)/0.140(0.010), BisGMA 0.060(0.004)/0.040(0.002), HgCl{sub 2} 0.015(0.001)/0.050(0.006), and MeHgCl 0.004(0.001)/0.005(0.001). Following EC{sub 50} values were found [LDH: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 9.490(0.300)/7.890(1.230), TEGDMA 2.300(0.470)/1.950(0.310), UDMA 0.200(0.007)/0.100(0.007), BisGMA 0.070(0.005)/0.100(0.002), and MeHgCl 0.014(0.006)/0.010(0.003). In both assays, the following range of increased toxicity was found for composite components (24 and 48 h): HEMA < TEGDMA < UDMA < BisGMA. In both assays, MeHgCl was the most toxic substance. In the BrdU assay, Hg{sup 2+} was about fourfold less toxic than MeHgCl but Hg{sup 2+} was about fourfold more toxic than BisGMA. In the BrdU test, a significantly (P<0.05) decreased toxicity was observed for Hg{sup 2+} at 48 h, compared to the 24 h

Converting Hg-1212 to Tl-2212 via Tl-Hg cation exchange in combination with Tl cation intercalation

International Nuclear Information System (INIS)

Zhao Hua; Wu, Judy Z

2007-01-01

In a cation exchange process developed recently for epitaxy of HgBa 2 CaCu 2 O 6 (Hg-1212) thin films, TlBa 2 CaCu 2 O 7 (Tl-1212) or Tl 2 Ba 2 CaCu 2 O 9 (Tl-2212) precursor films were employed as the precursor matrices and Hg-1212 was obtained by replacing Tl cations on the precursor lattice with Hg cations. The reversibility of the cation exchange dictates directly the underlying mechanism. Following our recent success in demonstrating a complete reversibility within '1212' structure, we show the conversion from Hg-1212 to Tl-2212 can be achieved via two steps: conversion from Hg-1212 to Tl-1212 followed by Tl intercalation to form double Tl-O plans in each unit cell. The demonstrated reversibility of the cation exchange process has confirmed the process is a thermal perturbation of weakly bonded cations on the lattice and the direction of the process is determined by the population ratio between the replacing cations and that to be replaced

New compounds bearing [M(S_2O_7)_3]"2"- anions (M = Si, Ge, Sn): Syntheses and characterization of A_2[Si(S_2O_7)_3] (A = Na, K, Rb), A_2[Ge(S_2O_7)_3] (A = Li, Na, K, Rb, Cs), A_2[Sn(S_2O_7)_3] (A = Na, K), and the unique germanate Hg_2[Ge(S_2O_7)_3]Cl_2 with cationic "1_∞[HgCl_2_/_2]"+ chains

International Nuclear Information System (INIS)

Logemann, Christian; Witt, Julia; Wickleder, Mathias S.; Gunzelmann, Daniel; Senker, Juergen

2012-01-01

The reaction of the group 14 tetrachlorides MCl_4 (M = Si, Ge, Sn) with oleum (65 % SO_3) at elevated temperatures led to the unique anionic complexes [M(S_2O_7)_3]"2"- that show the central M atoms in coordination of three chelating S_2O_7"2"- groups. The mean distances M-O within the complexes increase from 175 pm (M = Si) via 186 pm (M = Ge) up to 200 pm (M = Sn). The charge balance for the [M(S_2O_7)_3]"2"- anions is achieved by alkaline metal ions A"+ (A = Li, Na, K, Rb, Cs) which were implemented in the syntheses in form of their sulfates. The size of the A"+ ions, i.e. their coordination requirement causes the crystallographic differences in the crystal structures, while the structure of the complex [M(S_2O_7)_3]"2"- anions remains essentially unaffected. Furthermore, we were able to characterize the unique germanate Hg_2[Ge(S_2O_7)_3]Cl_2 which forms when HgCl_2 is added as a source for the counter cation. The Hg"2"+ and the Cl"- ions form infinite cationic chains according to "1_∞[HgCl_2_/_2]"+ which take care for the charge compensation. For selected examples of the compounds the thermal behavior has been monitored by means of thermal analyses and X-ray powder diffraction. For A being an alkaline metal the decomposition product is a mixture of the sulfates A_2SO_4 and the dioxides MO_2, whereas Hg_2[Ge(S_2O_7)_3]Cl_2 shows a more complicated decomposition. The tris-(disulfato)-silicate Na_2[Si(S_2O_7)_3] has additionally been examined by solid state "2"9Si and "2"3Na NMR spectroscopic measurements. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Bis(2-methyl-4-nitroanilinium tetrachloridomercurate(II

Directory of Open Access Journals (Sweden)

Andreas Lemmerer

2008-12-01

Full Text Available The title compound, (C7H9N2O22[HgCl4], self-assembles into cationic organic bilayers containing the 2-methyl-4-nitroanilinium cations, sandwiched between anionic inorganic layers built up by the distorted tetrahedral [HgCl4]2− groups. The organic sheets are interlinked through weak C—H...O hydrogen bonds, while they interact with the anionic part via strong charge-assisted N+—H...Cl—Hg hydrogen bonds. The [HgCl4]2− anions are bisected by a mirror plane passing through the metal and two of the chloride ions.

Oxidative addition of diphenyl disulfide across a Ta=Ta bond. Preparation and characterization of [TaCl3(Me2S)]2(μ-SPh)2

International Nuclear Information System (INIS)

Campbell, G.C.; Canich, J.A.M; Cotton, F.A.; Duraj, S.A.; Haw, J.F.

1986-01-01

The tantalum complex (SMe 2 )Cl 2 Ta(μ-Cl) 2 (μ-SMe 2 )TaCl 2 (SMe 2 ), possessing a sigma 2 π 2 Ta=Ta double bond, reacts readily with PhSSPh to give (SMe 2 )Cl 3 Ta(μ-SPh) 2 TaCl 2 (SMe 2 ). In this reaction, the starting material loses the bridging SMe 2 ligand and two chloride bridges are broken while only two new SPh bridges are formed in the final product. This oxidative-addition reaction of the S-S single bond to the Ta=Ta double bond converts the face-sharing bioctahedron structure of the starting compound to an edge-sharing bioctahedron structure in the final dimer, with concomitant change of the oxidation state of tantalum from III to IV. The product is the first example of a d 1 -d 1 ditantalum thiolate-bridged dimer. Important structural data for (SMe 2 )Cl 3 Ta(μ-SPh) 2 TaCl 3 (SMe 2 ), which has an inversion center, are determined. The new compound crystallizes in the monoclinic space group C2/c with a = 17.934 (5) A, b = 12.445 (4) A, c = 11.705 (4) A, β = 92.50 (3) 0 , V = 2610 (2) A 3 , and Z = 4. Solid-state 13 C NMR spectroscopy with cross polarization and magic-angle spinning (CP/MAS) at 28 and -103 0 C provides evidence that this compound is diamagnetic. 12 references, 3 figures, 4 tables

The use of 197HgCl2 in the study of pseudo-tumoral pulmonary afflictions

International Nuclear Information System (INIS)

Biagini, C.; Centi Colella, A.; Pigorini, F.

1975-01-01

The utility of examinations with 197 HgCl 2 has been shown in the study of pseudo-tumoral pulmonary afflictions. The following points seem to be the most important. The real possibility of differential diagnosis between benign and malignant tumors if the uptake of radio-mercury is related to the volume of the lesion. The possibility of differential diagnosis between cancers and the after-effects of more inflammatory TBC and non-TBC processes (inactive tuberculomas, fibroses). In sub-acute and chronic inflammatory lesions, some indication is furnished by the behavior of the uptake ratio at 24 and 72 hours. The topographical definition of the tumoral lesion in the case where there are associated secondary phenomena (atelectasis, a small quantity of pleural effusion). Individualization of extrapulmonary metastases which are situated at the level of the brain and the thoracic skeleton. Evaluation of the modifications of proliferative activities of cancers during radiologic or medical treatment [fr

Study on the covalence of Cu and chemical bonding in an inorganic fullerene-like molecule, [CuCl]20[Cp*FeP5]12[Cu-(CH3CN)2+Cl-]5, by a density functional approach

Institute of Scientific and Technical Information of China (English)

WANG; Bingwu; XU; Guangxian; CHEN; Zhida

2004-01-01

The electronic structure and chemical bonding in a recently synthesized inorganic fullerene-like molecule, {[CuCl]20[Cp*FeP5]12 [Cu(CH3CN)+2Cl-]5}, has been studied by a density functional approach. Geometrical optimization of the three basic structural units of the molecule is performed with Amsterdam Density Functional Program. The results are in agreement with the experiment. Localized MO's obtained by Boys-Foster method give a clear picture of the chemical bonding in this molecule. The reason why CuCl can react with Cp*FeP5 in solvent CH3CN to form the fullerene-like molecule is explained in terms of the soft-hard Lewis acid base theory and a new concept of covalence.

Persistent Hg contamination and occurrence of Hg-methylating transcript (hgcA) downstream of a chlor-alkali plant in the Olt River (Romania).

Science.gov (United States)

Bravo, Andrea G; Loizeau, Jean-Luc; Dranguet, Perrine; Makri, Stamatina; Björn, Erik; Ungureanu, Viorel Gh; Slaveykova, Vera I; Cosio, Claudia

2016-06-01

Chlor-alkali plants using mercury (Hg) cell technology are acute point sources of Hg pollution in the aquatic environment. While there have been recent efforts to reduce the use of Hg cells, some of the emitted Hg can be transformed to neurotoxic methylmercury (MeHg). Here, we aimed (i) to study the dispersion of Hg in four reservoirs located downstream of a chlor-alkali plant along the Olt River (Romania) and (ii) to track the activity of bacterial functional genes involved in Hg methylation. Total Hg (THg) concentrations in water and sediments decreased successively from the initial reservoir to downstream reservoirs. Suspended fine size particles and seston appeared to be responsible for the transport of THg into downstream reservoirs, while macrophytes reflected the local bioavailability of Hg. The concentration and proportion of MeHg were correlated with THg, but were not correlated with bacterial activity in sediments, while the abundance of hgcA transcript correlated with organic matter and Cl(-) concentration, indicating the importance of Hg bioavailability in sediments for Hg methylation. Our data clearly highlights the importance of considering Hg contamination as a legacy pollutant since there is a high risk of continued Hg accumulation in food webs long after Hg-cell phase out.

Intermolecular C-H···O, Cl···Cl and π-π interactions in the 2-dichloromethyl derivative of vitamin K3.

Science.gov (United States)

Soave, Raffaella; Colombo, Pietro

2013-12-15

The title 1,4-naphthoquinone, 2-dichloromethyl-3-methyl-1,4-dihydronaphthalene-1,4-dione, C12H8Cl2O2, is a chlorinated derivative of vitamin K3, which is a synthetic compound also known as menadione. Molecules of (I) are planar and lie on a crystallographic mirror plane (Z' = 0.5) in the space group Pnma. They are connected to each other by C-H···O hydrogen bonds, forming two-dimensional layers parallel to the ac plane. In addition, Cl···Cl and π-π interactions link adjacent molecules in different layers, thus forming zigzag ribbons along the b axis, such that a three-dimensional architecture is generated.

First-principle calculations of the structural, elastic and bonding properties of Cs{sub 2}NaLnCl{sub 6} (Ln=La–Lu) cubic elpasolites

Energy Technology Data Exchange (ETDEWEB)

Ma, C.G.; Liu, D.X.; Feng, B.; Tian, Y.; Li, L. [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Brik, M.G., E-mail: mikhail.brik@ut.ee [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, Ravila 14C, Tartu 50411 (Estonia); Institute of Physics, Jan Dlugosz University, Armii Krajowej 13/15, PL-42200 Czestochowa (Poland)

2016-01-15

For the first time the structural, elastic and bonding properties of 15 elpasolite crystals Cs{sub 2}NaLnCl{sub 6} (Ln denotes all lanthanides from La to Lu) were calculated systematically using the CRYSTAL09 program. Several trends in the variation of these properties in relation to the atomic number Z of the Ln ions were found; in particular, the lattice parameter of these compounds decreases with Z (which can lead to the increased crystal field splittings of the 5d states for the heavier Ln ions), whereas the elastic constants and Debye temperature increase. The degree of covalency of the Ln–Cl chemical bonds is increased toward the end of the lanthanide series. - Highlights: • Structural, elastic and bonding properties of 15 cubic elpasolites Cs{sub 2}NaLnCl{sub 6} (Ln=La,…,Lu) are calculated. • Relations between these quantities and Ln atomic number were found. • Possible correlation between the elastic properties and Stokes shift is proposed.

Do inflation-linked bonds contain information about future inflation?

Directory of Open Access Journals (Sweden)

José Valentim Machado Vicente

2013-06-01

Full Text Available There is a widespread belief that inflation-linked bonds are a direct source of information about inflation expectations. In this paper we address this issue by analyzing the relationship between break-even inflation (the difference between nominal and real yields and future inflation. The dataset is extracted from Brazilian Treasury bonds covering the period from April 2005 to April 2011. We find that break-even inflation is an unbiased forecast only of the 3-month and 6-month ahead inflation. For medium horizons (12 and 18 months, break-even inflation has weak explanatory power of future inflation. Over long horizons (24 and 30 months, we report a significant, but counterintuitive, negative relationship between the break-even and realized inflation rates.

1D and 2D assembly structures by imidazole···chloride hydrogen bonds of iron(II) complexes [Fe(II)(HL(n-Pr))3]Cl·Y (HL(n-Pr) = 2-methylimidazol-4-yl-methylideneamino-n-propyl; Y = AsF6, BF4) and their spin states.

Science.gov (United States)

Fujinami, Takeshi; Nishi, Koshiro; Matsumoto, Naohide; Iijima, Seiichiro; Halcrow, Malcolm A; Sunatsuki, Yukinari; Kojima, Masaaki

2011-12-07

Two Fe(II) complexes fac-[Fe(II)(HL(n-Pr))(3)]Cl·Y (Y = AsF(6) (1) and BF(4) (2)) were synthesized, where HL(n-Pr) is 2-methylimidazole-4-yl-methylideneamino-n-propyl. Each complex-cation has the same octahedral N(6) geometry coordinated by three bidentate ligands and assumes facial-isomerism, fac-[Fe(II)(HL(n-Pr))(3)](2+) with Δ- and Λ-enantiomorphs. Three imidazole groups per Δ- or Λ-fac-[Fe(II)(HL(n-Pr))(3)](2+) are hydrogen-bonded to three Cl(-) ions or, from the viewpoint of the Cl(-) ion, one Cl(-) ion is hydrogen-bonded to three neighbouring fac-[Fe(II)(HL(n-Pr))(3)](2+) cations. The 3 : 3 NH···Cl(-) hydrogen bonds between Δ- or Λ-fac-[Fe(II)(HL(n-Pr))(3)](2+) and Cl(-) generate two kinds of assembly structures. The directions of the 3 : 3 NH···Cl(-) hydrogen bonds and hence the resulting assembly structures are determined by the size of the anion Y, though Y is not involved into the network structure and just accommodated in the cavity. Compound 1 has a 1D ladder structure giving a larger cavity, in which the Δ- and Λ-fac-[Fe(II)(HL(n-Pr))(3)](2+) enantiomorphs are bridged by two NH···Cl(-) hydrogen bonds. Compound 2 has a 2D network structure with a net unit of a cyclic trimer of {fac-[Fe(II)(HL(n-Pr))(3)](2+)···Cl(-)}(3) giving a smaller cavity, in which Δ- or Λ-fac-[Fe(II)(HL(n-Pr))(3)](2+) species with the same chirality are linked by NH···Cl(-) hydrogen bonds to give a homochiral 2D network structure. Magnetic susceptibility and Mössbauer spectral measurements demonstrated that compound 1 showed an abrupt one-step spin crossover with 4.0 K thermal hysteresis of T(c↓) = 125.5 K and T(c↑) = 129.5 K and compound 2 showed no spin transition and stayed in the high-spin state over the 5-300 K temperature range.

Brain, kidney and liver sup 203 Hg-methyl mercury uptake in the rat: Relationship to the neutral amino acid carrier

Energy Technology Data Exchange (ETDEWEB)

Aschner, M [Department of Pharmacology and Toxicology, and the Interdepartmental Neuroscience Training Program, Albany Medical College, Albany, NY (USA)

1989-01-01

To investigate the effect of L-neutral amino acids on tissue levels of methyl mercury in the adult animal, rats were infused into the external jugular vein with solutions containing (a) 0.05 mM {sup 203}Hg-MeHgCl and saline, (b) 0.05 mM {sup 203}Hg-MgHgCl-0.1 mM L-cysteine, (c) 0.05 mM {sup 203}Hg-MeHgCl-0.1 mM L-cysteine-0.1 mM L-methionine, (d) 0.05 mM {sup 203}Hg-MeHgCl-0.1 mM L-leucine, or (e) 0.05 mM {sup 203}Hg-MeHgCl-0.1 mM L-cysteine-0.1 mM L-leucine. Groups of animals were sacrificed at 3 min. 7 hr, and 96 hr. Brain, kidney, and liver {sup 203}Hg radioactivity was measured by means of gamma-scintillation spectrometry. Brain {sup 203}Hg concentrations L-cysteine treated animals were significantly higher compared with saline treated animals (P<0.05) at 3 min., 7 hr and 96 hr. The coinjection or coinfusion of methyl mercury with L-cysteine and L-methionine abolished the L-cysteine-mediated brain {sup 203}Hg uptake (P<0.05), at each sacrifice time. Kidney and liver {sup 203}Hg concentrations were not significantly different in any of the treatment groups compared with controls, irrespective of the sacrifice time. Furthermore, the percentage of diffusible {sup 203}Hg (non-protein bound) at each sacrifice time was not statistically different irrespective of the treatment assigned. These results suggest that methyl mercury L-cysteine conjugates in the plasma may share a common transport step with the L-neutral amino acid carrier transport system and indicate the presence in brain capillaries of a transport system capable of selectively mediating methyl mercury uptake across the capillary endothelial cell membrane. (author).

AIEgens for dark through-bond energy transfer: design, synthesis, theoretical study and application in ratiometric Hg2+ sensing.

Science.gov (United States)

Chen, Yuncong; Zhang, Weijie; Cai, Yuanjing; Kwok, Ryan T K; Hu, Yubing; Lam, Jacky W Y; Gu, Xinggui; He, Zikai; Zhao, Zheng; Zheng, Xiaoyan; Chen, Bin; Gui, Chen; Tang, Ben Zhong

2017-03-01

A novel dark through-bond energy transfer (DTBET) strategy is proposed and applied as the design strategy to develop ratiometric Hg 2+ sensors with high performance. Tetraphenylethene ( TPE ) derivatives with aggregation-induced emission (AIE) characteristics are selected as dark donors to eliminate emission leakage from the donors. The TBET mechanism has been adopted since it experiences less influence from spectral overlapping than Förster resonance energy transfer (FRET), making it more flexible for developing cassettes with large pseudo-Stokes shifts. In this work, energy transfer from the TPE derivatives (dark donor) to a rhodamine moiety (acceptor) was illustrated through photophysical spectroscopic studies and the energy transfer efficiency (ETE) was found to be up to 99%. In the solution state, no emission from the donors was observed and large pseudo-Stokes shifts were achieved (>280 nm), which are beneficial for biological imaging. Theoretical calculations were performed to gain a deeper mechanistic insight into the DTBET process and the structure-property relationship of the DTBET cassettes. Ratiometric Hg 2+ sensors were rationally constructed based on the DTBET mechanism by taking advantage of the intense emission of TPE aggregates. The Hg 2+ sensors exhibited well resolved emission peaks. >6000-fold ratiometric fluorescent enhancement is also achieved and the detection limit was found to be as low as 0.3 ppb. This newly proposed DTBET mechanism could be used to develop novel ratiometric sensors for various analytes and AIEgens with DTBET characteristics will have great potential in various areas including light harvesting materials, environmental science, chemical sensing, biological imaging and diagnostics.

Oxidative addition of the chloromethane C-Cl bond to Pd, an ab initio benchmark and DFT validation study

NARCIS (Netherlands)

de Jong, G.T.; Bickelhaupt, F.M.

2006-01-01

We have computed a state-of-the-art benchmark potential energy surface (PES) for the archetypal oxidative addition of the chloromethane C-Cl bond to the palladium atom and have used this to evaluate the performance of 26 popular density functionals, covering LDA, GGA, meta-GGA, and hybrid density

Ab initio investigation of the structural and electronic properties of amorphous HgTe.

Science.gov (United States)

Zhao, Huxian; Chen, Xiaoshuang; Lu, Jianping; Shu, Haibo; Lu, Wei

2014-01-29

We present the structure and electronic properties of amorphous mercury telluride obtained from first-principle calculations. The initial configuration of amorphous mercury telluride is created by computation alchemy. According to different exchange–correlation functions in our calculations, we establish two 256-atom models. The topology of both models is analyzed in terms of radial and bond angle distributions. It is found that both the Te and the Hg atoms tend to be fourfold, but with a wrong bond rate of about 10%. The fraction of threefold and fivefold atoms also shows that there are a significant number of dangling and floating bonds in our models. The electronic properties are also obtained. It is indicated that there is a bandgap in amorphous HgTe, in contrast to the zero bandgap for crystalline HgTe. The structures of the band tail and defect states are also discussed.

Use of /sup 197/HgCl/sub 2/ in the study of pseudo-tumoral pulmonary afflictions

Energy Technology Data Exchange (ETDEWEB)

Biagini, C; Centi Colella, A; Pigorini, F [Rome Univ. (Italy)

1975-01-01

The utility of examinations with /sup 197/HgCl/sub 2/ has been shown in the study of pseudo-tumoral pulmonary afflictions. The following points seem to be the most important. The real possibility of differential diagnosis between benign and malignant tumors if the uptake of radio-mercury is related to the volume of the lesion. The possibility of differential diagnosis between cancers and the after-effects of more inflammatory TBC and non-TBC processes (inactive tuberculomas, fibroses). In sub-acute and chronic inflammatory lesions, some indication is furnished by the behavior of the uptake ratio at 24 and 72 hours. The topographical definition of the tumoral lesion in the case where there are associated secondary phenomena (atelectasis, a small quantity of pleural effusion). Individualization of extrapulmonary metastases which are situated at the level of the brain and the thoracic skeleton. Evaluation of the modifications of proliferative activities of cancers during radiologic or medical treatment.

Spectral, thermal, electrochemical and analytical studies on Cd(II) and Hg(II) thiosemicarbazone complexes

Science.gov (United States)

El-Asmy, A. A.; El-Gammal, O. A.; Saleh, H. S.

2008-11-01

The coordination characteristic of the investigated thiosemicarbazones towards hazard pollutants, Cd(II) and Hg(II), becomes the first goal. Their complexes have been studied by microanalysis, thermal, electrochemical and spectral (electronic, IR and MS) studies. The substitutent (salicylaldehyde, acetophenone, benzophenone, o-hydroxy- p-methoxybenzophenone or diacetylmonoxime) plays an important role in the complex formation. The coordination sites were the S for thiosemicarbazide (HTS); NN for benzophenone thiosemicarbazone (HBTS); NS for acetophenone thiosemicarbazone (HATS) and salicylaldehyde thiosemicarbazone (H 2STS); NNS or NSO for diacetylmonoxime thiosemicarbazone (H 2DMTS). The stability constants of Hg(II) complexes were higher than Cd(II). The kinetic and thermodynamic parameters for the different thermal decomposition steps in the complexes have been evaluated. The activation energy values of the first step ordered the complexes as: [Cd(H 2STS)Cl 2]H 2O > [Cd(H 2DAMTS)Cl 2] > [Cd(HBTS) 2Cl 2]2H 2O > [Cd(HATS) 2Cl 2]. The CV of [Cd(H 2STS)Cl 2]H 2O and [Hg(HBTS)Cl 2] were recorded. The use of H 2DMTS as a new reagent for the separation and determination of Cd(II) ions from water and some synthetic samples using flotation technique is aimed to be discussed.

Structure and bonding of transition metal-boryl compounds. Theoretical study of [(PH3)2(CO)ClOs-BR2] and [(PH3)2(CO)2ClOs-BR2] (BR2 = BH2, BF2, B(OH)2, B(OCH=CHO), Bcat).

Science.gov (United States)

Giju, K T; Bickelhaupt, F M; Frenking, G

2000-10-16

Quantum chemical DFT calculations using the B3LYP functionals have been carried out for the electronically unsaturated 16 VE five-coordinate osmium boryl-complexes [(PH3)2(CO)ClOs-BR2] and the 18 VE six-coordinate complexes [(PH3)2(CO)2ClOs-BR2] with BR2 = BH2, BF2, B(OH)2, B(OHC=CHO), and Bcat (cat = catecholate O2C6H4). The bonding situation of the Os-BR2 bond was analyzed with the help of the NBO partitioning scheme. The Os-B bond dissociation energies of the 16 VE complexes are very high, and they do not change very much for the different boryl ligands. The 18 VE complexes have only slightly lower bond energies than the 16 VE species. The Os-B bond in both classes of compounds is provided by a covalent sigma-bond which is polarized toward osmium and by strong charge attraction. Os-->B pi-donation is not important for the Os-B binding interactions, except for the Os-BH2 complexes. The stability of the boryl complexes [Os]-BR2 comes mainly from BB pi-donation. The intraligand charge distribution of the BR2 group changes little when the Os-B bond is formed, except for BH2. The CO ligand in [(PH3)2(CO)2ClOs-BR2] which is trans to BR2 has a relatively weak bond to the osmium atom.

Cyclotron resonance and De Haas-Van Alphen effect in (BEDT-TTF) sub 8 Hg sub 4 Cl sub 1 sub 2 (C sub 6 H sub 5 Cl) sub 2 organic conductor

CERN Document Server

Voskobojnikov, I B; Samarin, N A; Cluchanko, N E; Lyubovskaya, R N; Moshchalkov, V V

2002-01-01

Within 0.33-1.44 K temperature range at B <= 50 T magnetic field values one measured the De Haas-Van Alphen effect for (BEDT-TTF) sub 8 Hg sub 4 Cl sub 1 sub 2 (C sub 6 H sub 5 Cl) sub 2 organic quasi-two-dimensional conductor. Analysis of quantum oscillations with regard to data on cyclotron resonance derived for 40-120 GHz frequency interval enabled to determine that a complex spectrum of quantum oscillations was formed by alpha approx 256 T and beta approx 670-610 T fundamental frequencies as well as, by combination and multiple frequencies. It is shown that nature of temperature rearrangement of oscillation spectrum may be interpreted in terms of model taking account of occurrence of magnetic phase transition at T sub c approx 0.9 K and proximity of a fundamental frequency with m* = 1.48m sub 0 efficient mass to the spin dumping condition

Hg tolerance and biouptake of an isolated pigmentation yeast Rhodotorula mucilaginosa.

Science.gov (United States)

Liu, Bing; Wang, Chaogang; Liu, Danxia; He, Ning; Deng, Xu

2017-01-01

A pigmented yeast R1 with strong tolerance to Hg2+ was isolated. Phylogenetic identification based on the analysis of 26S rDNA and ITS revealed R1 is a Rhodotorula mucilaginosa species. R1 was able to grow in the presence of 80 mg/L Hg2+, but the lag phase was much prolonged compared to its growth in the absence of Hg2+. The maximum Hg2+ binding capacity of R1 was 69.9 mg/g, and dead cells could bind 15% more Hg2+ than living cells. Presence of organic substances drastically reduced bioavailability of Hg2+ and subsequently decreased Hg2+ removal ratio from aqueous solution, but this adverse effect could be remarkably alleviated by the simultaneous process of cell propagation and Hg2+ biouptake with actively growing R1. Furthermore, among the functional groups involved in Hg2+ binding, carboxyl group contributed the most, followed by amino & hydroxyl group and phosphate group. XPS analysis disclosed the mercury species bound on yeast cells was HgCl2 rather than HgO or Hg0.

Ab initio investigation of the structural and electronic properties of amorphous HgTe

International Nuclear Information System (INIS)

Zhao, Huxian; Chen, Xiaoshuang; Shu, Haibo; Lu, Wei; Lu, Jianping

2014-01-01

We present the structure and electronic properties of amorphous mercury telluride obtained from first-principle calculations. The initial configuration of amorphous mercury telluride is created by computation alchemy. According to different exchange–correlation functions in our calculations, we establish two 256-atom models. The topology of both models is analyzed in terms of radial and bond angle distributions. It is found that both the Te and the Hg atoms tend to be fourfold, but with a wrong bond rate of about 10%. The fraction of threefold and fivefold atoms also shows that there are a significant number of dangling and floating bonds in our models. The electronic properties are also obtained. It is indicated that there is a bandgap in amorphous HgTe, in contrast to the zero bandgap for crystalline HgTe. The structures of the band tail and defect states are also discussed. (paper)

Development of a Cl-impregnated activated carbon for entrained-flow capture of elemental mercury.

Science.gov (United States)

Ghorishi, S Behrooz; Keeney, Robert M; Serre, Shannon D; Gullett, Brian K; Jozewicz, Wojciech S

2002-10-15

Efforts to discern the role of an activated carbon's surface functional groups on the adsorption of elemental mercury (Hg0) and mercuric chloride demonstrated that chlorine (Cl) impregnation of a virgin activated carbon using dilute solutions of hydrogen chloride leads to increases (by a factor of 2-3) in fixed-bed capture of these mercury species. A commercially available activated carbon (DARCO FGD, NORITAmericas Inc. [FGD])was Cl-impregnated (Cl-FGD) [5 lb (2.3 kg) per batch] and tested for entrained-flow, short-time-scale capture of Hg0. In an entrained flow reactor, the Cl-FGD was introduced in Hg0-laden flue gases (86 ppb of Hg0) of varied compositions with gas/solid contact times of about 3-4 s, resulting in significant Hg0 removal (80-90%), compared to virgin FGD (10-15%). These levels of Hg0 removal were observed across a wide range of very low carbon-to-mercury weight ratios (1000-5000). Variation of the natural gas combustion flue gas composition, by doping with nitrogen oxides and sulfur dioxide, and the flow reactor temperature (100-200 degrees C) had minimal effects on Hg0 removal bythe Cl-FGD in these carbon-to-mercury weight ratios. These results demonstrate significant enhancement of activated carbon reactivity with minimal treatment and are applicable to combustion facilities equipped with downstream particulate matter removal such as an electrostatic precipitator.

Stepwise Ti-Cl, Ti-CH3, and Ti-C6H5 bond dissociation enthalpies in bis(pentamethylcyclopentadienyl)titanium complexes

NARCIS (Netherlands)

Dias, Alberto R.; Salema, Margarida S.; Martinho Simões, Jose A.; Pattiasina, Johannes W.; Teuben, Jan H.

1988-01-01

Reaction-solution calorimetric studies involving the complexes Ti[η5-C5(CH3)5]2(CH3)2, Ti[η5-C5(CH3)5]2(CH3), Ti[η5-C5(CH3)5]2(C6H5), Ti[η5-C5(CH3)5]2Cl2, and Ti[η5-C5(CH3)5]2Cl, have enabled derivation of titanium-carbon and titanium-chlorine stepwise bond dissociation enthalpies in these species.

Biogeochemical analysis of ancient Pacific Cod bone suggests Hg bioaccumulation was linked to paleo sea level rise and climate change

Directory of Open Access Journals (Sweden)

Maribeth S. Murray

2015-02-01

Full Text Available Deglaciation at the end of the Pleistocene initiated major changes in ocean circulation and distribution. Within a brief geological time, large areas of land were inundated by sea-level rise and today global sea level is 120 m above its minimum stand during the last glacial maximum. This was the era of modern sea shelf formation; climate change caused coastal plain flooding and created broad continental shelves with innumerable consequences to marine and terrestrial ecosystems and human populations. In Alaska, the Bering Sea nearly doubled in size and stretches of coastline to the south were flooded, with regional variability in the timing and extent of submergence. Here we suggest how past climate change and coastal flooding are linked to mercury bioaccumulation that could have had profound impacts on past human populations and that, under conditions of continued climate warming, may have future impacts. Biogeochemical analysis of total mercury (tHg and 13C/15N ratios in the bone collagen of archaeologically recovered Pacific Cod (Gadus macrocephalus bone shows high levels of tHg during early/mid-Holocene. This pattern cannot be linked to anthropogenic activity or to food web trophic changes, but may result from natural phenomena such as increases in productivity, carbon supply and coastal flooding driven by glacial melting and sea-level rise. The coastal flooding could have led to increased methylation of Hg in newly submerged terrestrial land and vegetation. Methylmercury is bioaccumulated through aquatic food webs with attendant consequences for the health of fish and their consumers, including people. This is the first study of tHg levels in a marine species from the Gulf of Alaska to provide a time series spanning nearly the entire Holocene and we propose that past coastal flooding resulting from climate change had the potential to input significant quantities of Hg into marine food webs and subsequently to human consumers.

Halogen Bonding Involving CO and CS with Carbon as the Electron Donor

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Janet E. Del Bene

2017-11-01

Full Text Available MP2/aug’-cc-pVTZ calculations have been carried out to investigate the halogen-bonded complexes formed when CO and CS act as electron-pair donors through C to ClF, ClNC, ClCl, ClOH, ClCN, ClCCH, and ClNH2. CO forms only complexes stabilized by traditional halogen bonds, and all ClY molecules form traditional halogen-bonded complexes with SC, except ClF which forms only an ion-pair complex. Ion-pair complexes are also found on the SC:ClNC and SC:ClCl surfaces. SC:ClY complexes stabilized by traditional halogen bonds have greater binding energies than the corresponding OC:ClY complexes. The largest binding energies are found for the ion-pair SC–Cl+:−Y complexes. The transition structures which connect the complex and the ion pair on SC:ClNC and SC:ClCl potential surfaces provide the barriers for inter-converting these structures. Charge-transfer from the lone pair on C to the σ-hole on Cl is the primary charge-transfer interaction stabilizing OC:ClY and SC:ClY complexes with traditional halogen bonds. A secondary charge-transfer occurs from the lone pairs on Cl to the in-plane and out-of-plane π antibonding orbitals of ClY. This secondary interaction assumes increased importance in the SC:ClNH2 complex, and is a factor leading to its unusual structure. C–O and C–S stretching frequencies and 13C chemical shieldings increase upon complex formation with ClY molecules. These two spectroscopic properties clearly differentiate between SC:ClY complexes and SC–Cl+:−Y ion pairs. Spin–spin coupling constants 1xJ(C–Cl for OC:ClY complexes increase with decreasing distance. As a function of the C–Cl distance, 1xJ(C–Cl and 1J(C–Cl provide a fingerprint of the evolution of the halogen bond from a traditional halogen bond in the complexes, to a chlorine-shared halogen bond in the transition structures, to a covalent bond in the ion pairs.

Immobilization of aqueous Hg(II) by mackinawite (FeS)

International Nuclear Information System (INIS)

Liu Jianrong; Valsaraj, Kalliat T.; Devai, Istvan; DeLaune, R.D.

2008-01-01

As one of the major constituents of acid volatile sulfide (AVS) in anoxic sediments, mackinawite (FeS) is known for its ability to scavenge trace metals. The interaction between aqueous Hg(II) (added as HgCl 2 ) and synthetic FeS was studied via batch sorption experiments conducted under anaerobic conditions. Due to the release of H + during formation of hydrolyzed Hg(II) species which is more reactive than Hg 2+ in surface adsorption, the equilibrium pH decreased with the increase in Hg(II)/FeS molar ratio. Counteracting the loss of FeS solids at lower pH, the maximum capacity for FeS to remove aqueous Hg(II) was approximately 0.75 mol Hg(II) (mol FeS) -1 . The comparison of X-ray power diffraction (XRPD) patterns of synthetic FeS sorbent before and after sorption showed that the major products formed from the interaction between FeS and the aqueous Hg(II) were metacinnabar, cinnabar, and mercury iron sulfides. With the addition of FeS at 0.4 g L -1 to a 1 mM Hg(II) solution with an initial pH of 5.6, Fe 2+ release was approximately 0.77 mol Fe 2+ per mol Hg(II) removed, suggesting that 77% of Hg(II) was removed via precipitation reaction under these conditions, with 23% of Hg(II) removed by adsorption. Aeration does not cause significant release of Hg(II) into the water phase

Novel cross-linked alcohol-insoluble solid (CL-AIS) affinity gel from pea pod for pectinesterase purification.

Science.gov (United States)

Wu, Ming-Chang; Lin, Guan-Hui; Wang, Yuh-Tai; Jiang, Chii-Ming; Chang, Hung-Min

2005-10-05

Alcohol-insoluble solids (AIS) from pea pod were cross-linked (CL-AIS) and used as an affinity gel matrix to isolate pectin esterases (PEs) from tendril shoots of chayote (TSC) and jelly fig achenes (JFA), and the results were compared with those isolated by ion-exchange chromatography with a commercial resin. CL-AIS gel matrix in a column displayed poor absorption and purification fold of PE; however, highly methoxylated CL-AIS (HM-CL-AIS), by exposing CL-AIS to methanolic sulfuric acid to increase the degree of esterification (DE) to 92%, facilitated the enzyme purification. The purified TSC PE and JFA PE by the HM-CL-AIS column were proofed as a single band on an SDS-PAGE gel, showing that the HM-CL-AIS column was a good matrix for purification of PE, either with alkaline isoelectric point (pI) (TSC PE) or with acidic pI (JFA PE).

The mercury-richest europium amalgam Eu{sub 10}Hg{sub 55}

Energy Technology Data Exchange (ETDEWEB)

Tambornino, Frank; Hoch, Constantin [Department of Chemistry, Ludwig-Maximilians-Universitaet Muenchen (Germany)

2015-03-15

The mercury-richest europium amalgam Eu{sub 10}Hg{sub 55} was synthesized by isothermal electrocrystallization from a solution of EuI{sub 3}.8DMF in DMF on a reactive mercury cathode. The crystal structure shows remarkable complexity and polar metal-metal bonding. Closely related to the structures of mercury-rich amalgams A{sub 11-x}Hg{sub 55+x} (A = Na, Ca, Sr), it shows underoccupied Hg positions along [00z]. Eu{sub 10}Hg{sub 55} can be described as hettotype structure of the Gd{sub 14}Ag{sub 51} structure type. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

A ratiometric electrochemical biosensor for sensitive detection of Hg2+ based on thymine-Hg2+-thymine structure.

Science.gov (United States)

Xiong, Erhu; Wu, Liang; Zhou, Jiawan; Yu, Peng; Zhang, Xiaohua; Chen, Jinhua

2015-01-01

In this paper, a simple, selective and reusable electrochemical biosensor for the sensitive detection of mercury ions (Hg(2+)) has been developed based on thymine (T)-rich stem-loop (hairpin) DNA probe and a dual-signaling electrochemical ratiometric strategy. The assay strategy includes both "signal-on" and "signal-off" elements. The thiolated methylene blue (MB)-modified T-rich hairpin DNA capture probe (MB-P) firstly self-assembled on the gold electrode surface via Au-S bond. In the presence of Hg(2+), the ferrocene (Fc)-labeled T-rich DNA probe (Fc-P) hybridized with MB-P via the Hg(2+)-mediated coordination of T-Hg(2+)-T base pairs. As a result, the hairpin MB-P was opened, the MB tags were away from the gold electrode surface and the Fc tags closed to the gold electrode surface. These conformation changes led to the decrease of the oxidation peak current of MB (IMB), accompanied with the increase of that of Fc (IFc). The logarithmic value of IFc/IMB is linear with the logarithm of Hg(2+) concentration in the range from 0.5 nM to 5000 nM, and the detection limit of 0.08 nM is much lower than 10nM (the US Environmental Protection Agency (EPA) limit of Hg(2+) in drinking water). What is more, the developed DNA-based electrochemical biosensor could be regenerated by adding cysteine and Mg(2+). This strategy provides a simple and rapid approach for the detection of Hg(2+), and has promising application in the detection of Hg(2+) in real environmental samples. Copyright © 2014 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

Jensen, Kasper P.

2009-08-01

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

Sulfurization of Dissolved Organic Matter Increases Hg-Sulfide-Dissolved Organic Matter Bioavailability to a Hg-Methylating Bacterium.

Science.gov (United States)

Graham, Andrew M; Cameron-Burr, Keaton T; Hajic, Hayley A; Lee, Connie; Msekela, Deborah; Gilmour, Cynthia C

2017-08-15

Reactions of dissolved organic matter (DOM) with aqueous sulfide (termed sulfurization) in anoxic environments can substantially increase DOM's reduced sulfur functional group content. Sulfurization may affect DOM-trace metal interactions, including complexation and metal-containing particle precipitation, aggregation, and dissolution. Using a diverse suite of DOM samples, we found that susceptibility to additional sulfur incorporation via reaction with aqueous sulfide increased with increasing DOM aromatic-, carbonyl-, and carboxyl-C content. The role of DOM sulfurization in enhancing Hg bioavailability for microbial methylation was evaluated under conditions typical of Hg methylation environments (μM sulfide concentrations and low Hg-to-DOM molar ratios). Under the conditions of predicted metacinnabar supersaturation, microbial Hg methylation increased with increasing DOM sulfurization, likely reflecting either effective inhibition of metacinnabar growth and aggregation or the formation of Hg(II)-DOM thiol complexes with high bioavailability. Remarkably, Hg methylation efficiencies with the most sulfurized DOM samples were similar (>85% of total Hg methylated) to that observed in the presence of l-cysteine, a ligand facilitating rapid Hg(II) biouptake and methylation. This suggests that complexes of Hg(II) with DOM thiols have similar bioavailability to Hg(II) complexes with low-molecular-weight thiols. Overall, our results are a demonstration of the importance of DOM sulfurization to trace metal and metalloid (especially mercury) fate in the environment. DOM sulfurization likely represents another link between anthropogenic sulfate enrichment and MeHg production in the environment.

Mass-Dependent and -Independent Fractionation of Mercury Isotope during Gas-Phase Oxidation of Elemental Mercury Vapor by Atomic Cl and Br.

Science.gov (United States)

Sun, Guangyi; Sommar, Jonas; Feng, Xinbin; Lin, Che-Jen; Ge, Maofa; Wang, Weigang; Yin, Runsheng; Fu, Xuewu; Shang, Lihai

2016-09-06

This study presents the first measurement of Hg stable isotope fractionation during gas-phase oxidation of Hg(0) vapor by halogen atoms (Cl(•), Br(•)) in the laboratory at 750 ± 1 Torr and 298 ± 3 K. Using a relative rate technique, the rate coefficients for Hg(0)+Cl(•) and Hg(0)+Br(•) reactions are determined to be (1.8 ± 0.5) × 10(-11) and (1.6 ± 0.8) × 10(-12) cm(3) molecule(-1) s(-1), respectively. Results show that heavier isotopes are preferentially enriched in the remaining Hg(0) during Cl(•) initiated oxidation, whereas being enriched in the product during oxidation by Br(•). The fractionation factors for (202)Hg/(198)Hg during the Cl(•) and Br(•) initiated oxidations are α(202/198) = 0.99941 ± 0.00006 (2σ) and 1.00074 ± 0.00014 (2σ), respectively. A Δ(199)Hg/Δ(201)Hg ratio of 1.64 ± 0.30 (2σ) during oxidation of Hg(0) by Br atoms suggests that Hg-MIF is introduced by the nuclear volume effect (NVE). In contrast, the Hg(0) + Cl(•) reaction produces a Δ(199)Hg/Δ(201)Hg-slope of 1.89 ± 0.18 (2σ), which in addition to a high degree of odd-mass-number isotope MIF suggests impacts from MIF effects other than NVE. This reaction also exhibits significant MIF of (200)Hg (Δ(200)Hg, up to -0.17‰ in the reactant) and is the first physicochemical process identified to trigger (200)Hg anomalies that are frequently detected in atmospheric samples.

The mercury chromates Hg6Cr2O9 and Hg6Cr2O10-Preparation and crystal structures, and thermal behaviour of Hg6Cr2O9

International Nuclear Information System (INIS)

Weil, Matthias; Stoeger, Berthold

2006-01-01

The basic mercury(I) chromate(VI), Hg 6 Cr 2 O 9 (=2Hg 2 CrO 4 .Hg 2 O), has been obtained under hydrothermal conditions (200deg. C, 5 days) in the form of orange needles as a by-product from reacting elemental mercury and K 2 Cr 2 O 7 . Hydrothermal treatment of microcrystalline Hg 6 Cr 2 O 9 in demineralised water at 200deg. C for 3 days led to crystal growth of red crystals of the basic mercury(I, II) chromate(VI), Hg 6 Cr 2 O 10 (=2Hg 2 CrO 4 .2HgO). The crystal structures were solved and refined from single crystal X-ray data sets. Hg 6 Cr 2 O 9 : space group P2 1 2 1 2 1 , Z=4, a=7.3573(12), b=8.0336(13), c=20.281(3)A, 3492 structure factors, 109 parameters, R[F 2 >2σ(F 2 )]=0.0371, wR(F 2 all)=0.0517; Hg 6 Cr 2 O 10 : space group Pca2 1 , Z=4, a=11.4745(15), b=9.4359(12), c=10.3517(14)A, 3249 structure factors, 114 parameters, R[F 2 >2σ(F 2 )]=0.0398, wR(F 2 all)=0.0625. Both crystal structures are made up of an intricate mercury-oxygen network, subdivided into single building blocks [O-Hg-Hg-O] for the mercurous compound, and [O-Hg-Hg-O] and [O-Hg-O] for the mixed-valent compound. Hg 6 Cr 2 O 9 contains three different Hg 2 2+ dumbbells, whereas Hg 6 Cr 2 O 10 contains two different Hg 2 2+ dumbbells and two Hg 2+ cations. The Hg I -Hg I distances are characteristic and range between 2.5031(15) and 2.5286(9)A. All Hg 2 2+ groups exhibit an unsymmetrical oxygen environment. The oxygen coordination of the Hg 2+ cations is nearly linear with two tightly bonded O atoms at distances around 2.07A. For both structures, the chromate(VI) anions reside in the vacancies of the Hg-O network and deviate only slightly from the ideal tetrahedral geometry with average Cr-O distances of ca. 1.66A. Upon heating at temperatures above 385deg. C, Hg 6 Cr 2 O 9 decomposes in a four-step mechanism with Cr 2 O 3 as the end-product at temperatures above 620 deg. C

Assessment of Hg Pollution Released from a WWII Submarine Wreck (U-864) by Hg Isotopic Analysis of Sediments and Cancer pagurus Tissues.

Science.gov (United States)

Rua-Ibarz, Ana; Bolea-Fernandez, Eduardo; Maage, Amund; Frantzen, Sylvia; Valdersnes, Stig; Vanhaecke, Frank

2016-10-04

Hg pollution released from the U-864 submarine sunk during WWII and potential introduction of that Hg into the marine food chain have been studied by a combination of quantitative Hg and MeHg determination and Hg isotopic analysis via cold vapor generation multicollector inductively coupled plasma-mass spectrometry (CVG-MC-ICP-MS) in sediment and Cancer pagurus samples. The sediment pollution could be unequivocally linked with the metallic Hg present in the wreck. Crabs were collected at the wreck location and 4 nmi north and south, and their brown and claw meat were analyzed separately. For brown meat, the δ 202 Hg values of the individuals from the wreck location were shifted toward the isotopic signature of the sediment and, thus, the submarine Hg. Such differences were not found for claw meat. The isotope ratio results suggest direct ingestion of metallic Hg by C. pagurus but do not offer any proof for any other introduction of the submarine Hg into the marine food chain.

Optimization of properties of cement-bonded particleboard manufactured from cotton stalk and sawdust containing calcium chloride CaCl2 as an additive

Directory of Open Access Journals (Sweden)

morteza nazerian

2016-06-01

Full Text Available The aim of this study was investigation of hydration behavior and mechanical properties of cement-bonded particleboard manufactured from different ratio of cotton stalk to poplar wood particle, sawdust content and CaCl2 as additive at different weight ratios. At the first, curing time of cement paste containing different amount of additive (CaCl2 and wood and cotton fines was determined. Besides, the effect of additive (CaCl2 content, weight ratio of cotton to poplar wood particles and percentage of sawdust on modulus of rupture (MOR, modulus of elasticity (MOE and internal bonding (IB of cement-bonded particleboard was evaluated by response surface methodology (RSM. In order to optimize the properties of panels, a mathematical model equation (second order plan was done by a computer simulation program. According to results, there is a good coincidence between predicted values and actual values (R2 for MOR, MOE and IB was 0.93, 0.90 and 0.95, respectively. This study showed that the response surface methodology (RSM can be effectively used for modeling of panel properties. Results showed that using weight ratio of cotton to poplar particle 43:57 the MOR, MOE and IB of panels can be reached to maximum values (12.5, 2545 and 0.35 MPa, respectively. Simultaneously, application of 4.5% additive and 9% sawdust at had a positive effect on the properties of the panels.

Solving mercury (Hg) speciation in soil samples by synchrotron X-ray microspectroscopic techniques.

Science.gov (United States)

Terzano, Roberto; Santoro, Anna; Spagnuolo, Matteo; Vekemans, Bart; Medici, Luca; Janssens, Koen; Göttlicher, Jörg; Denecke, Melissa A; Mangold, Stefan; Ruggiero, Pacifico

2010-08-01

Direct mercury (Hg) speciation was assessed for soil samples with a Hg concentration ranging from 7 up to 240 mg kg(-1). Hg chemical forms were identified and quantified by sequential extractions and bulk- and micro-analytical techniques exploiting synchrotron generated X-rays. In particular, microspectroscopic techniques such as mu-XRF, mu-XRD and mu-XANES were necessary to solve bulk Hg speciation, in both soil fractions soil samples were metacinnabar (beta-HgS), cinnabar (alpha-HgS), corderoite (Hg(3)S(2)Cl(2)), and an amorphous phase containing Hg bound to chlorine and sulfur. The amount of metacinnabar and amorphous phases increased in the fraction soil components was observed. All the observed Hg-species originated from the slow weathering of an inert Hg-containing waste material (K106, U.S. EPA) dumped in the area several years ago, which is changing into a relatively more dangerous source of pollution. Copyright 2010 Elsevier Ltd. All rights reserved.

Importance of Dissolved Neutral Hg-Sulfides, Energy Rich Organic Matter and total Hg Concentrations for Methyl Mercury Production in Sediments

Science.gov (United States)

Drott, A.; Skyllberg, U.

2007-12-01

Methyl mercury (MeHg) is the mercury form that biomagnifies to the greatest extent in aquatic food webs. Therefore information about factors determining MeHg concentrations is critical for accurate risk assessment of contaminated environments. The concentration of MeHg in wetlands and sediments is the net result of: 1) methylation rates, 2) demethylation rates, and 3) input/output processes. In this study, the main controls on Hg methylation rates and total concentrations of MeHg, were investigated at eight sites in Sweden with sediments that had been subjected to local Hg contamination either as Hg(0), or as phenyl-Hg. Sediments were selected to represent a gradient in total Hg concentration, temperature climate, salinity, primary productivity, and organic C content and quality. Most sediments were high in organic matter content due to wood fibre efflux from pulp and paper industry. The pore water was analysed for total Hg, MeHg, DOC, H2S(aq), pH, DOC, Cl and Br. The chemical speciation of Hg(II) and MeHg in pore water was calculated using equilibrium models. Potential methylation and demethylation rates in sediments were determined in incubation experiments at 23° C under N2(g) for 48 h, after addition of isotopically enriched 201Hg(II) and Me204Hg. In all surface (0-20 cm) sediments there was a significant (pdetermined specific potential methylation rate constant (Km, day-1) and % MeHg (concentrations of MeHg normalized to total Hg) in the sediment. This indicates that MeHg production overruled degradation and input/output processes of MeHg in surface sediments, and that % MeHg in surface sediments may be used as a proxy for net production of MeHg. To our knowledge, these are the first data showing significant positive relationships between short term (48 h) MeHg production and longer term accumulation of MeHg, across a range of sites with different properties (1). If MeHg was not normalized to total Hg, the relationship was not significant. For sub-sets of

Notes on the physiology of Hg uptake by the kidney

International Nuclear Information System (INIS)

Raynaud, C.

1976-01-01

The kidney has many functions of which the best known is excretion, and the purpose of most functional exploration methods is to study the excretion capacity. The Hg uptake test explores another function, the uptake of metals and toxic substances. The uptake process involves an active transport through the peritubular membrane and a concentration inside the kidney cell in a bound or insoluble form. Transfer into the tubular lumen, if any, is quantitatively negligible and appears to be due to neither an active nor a passive transfer. This uptake process may be identified in vivo from the shape of the kidney and urine radioactivity curves, even when excretion and uptake are associated, the former curve rising slowly to a plateau while the latter, very low, also appears to reach a plateau. The kidney and urine 197 HgCl 2 radioactivity curves illustrate this process very well. The 197 Hg uptake fraction at the plateau level has been proposed has a kidney function exploration test, this value being related by a highly significant correlation to other quantitative tests such as inuline and PAH clearances, PAH Tm and urine concentration capacity. In rats the 197 HgCl 2 uptake area has been located, by measurements on dissected nephrons, at the pars recta and to a lesser extent the whole of the proximal convolution [fr

Atomic mass determinations for 183W and 199Hg and the mercury problem

International Nuclear Information System (INIS)

Barillari, D.K.; Vaz, J.V.; Barber, R.C.; Sharma, K.S.

2003-01-01

Recent modifications to the 'Manitoba II' high resolution mass spectrometer are described. Mass differences among the members of the triplet 199 Hg - 183 W 16 O- 12 C 2 35 Cl 5 have been measured. These self-consistent mass differences give masses for 183 W and 199 Hg, as well as the mass difference across the W to Hg region of the mass table. These masses and the mass difference provide important constraints for the least squares atomic mass evaluation

Effect of fluorination on the structure and superconducting properties of the Hg-1201 phase

International Nuclear Information System (INIS)

Abakumov, A.M.; Aleshin, V.A.; Antipov, E.V.; Mikhajlova, D.A.; Putilin, S.N.; Rozova, M.G.; Aksenov, V.L.; Balagurov, A.M.

1997-01-01

A fluorination of the reduced Hg-1201 phase with T c =61 K carried out with XeF 2 resulted first in an increase in T c up to 97 K and then in a decrease and even a suppression of superconductivity due to overdoping. Neutron power refinement performed on fluorinated HgBa 2 CuO 4 F δ samples showed twice the amount of extra fluorine (δ≅0.24 and 0.32) in comparison with those for the oxygenated Hg-1201 phases with close T c (δ=0.12 and 0.19). This supports the ionic model of the hole doping in the Hg-1201: 2 holes per extra oxygen and 1 hole per extra fluorine. The exchange of extra oxygen for a double amount of fluorine extends the shortening of the apical Cu-O bond distances, while the in-plane distances, as well as T c , do not vary. These results show that the structural nature of T c variation in Hg-1201 under high pressure can be mainly due to the compression of the in-plane Cu-O bond distances

Terlinguacreekite, Hg32+O2 Cl2, a new mineral species from the Perry pit, Mariposa mine, Terlingua mining district, Brewster County, Texas, U.S.A

Science.gov (United States)

Roberts, Andrew C.; Gault, Robert A.; Paar, W.H.; Cooper, M.A.; Hawthorne, F.C.; Burns, P.C.; Cisneros, S.; Foord, E.E.

2005-01-01

Terlinguacreekite, ideally Hg32+O2 Cl2, has a very pronounced subcell that is orthorhombic, space-group choices Imam, Imcm, Ima2 and 12cm, with unit-cell parameters refined from powder data: a 6.737(3), b 25.528(10), c 5.533(2) A??, V951.6(6) A??3, a:b:c 0.2639:1:0.2167, Z=8. The true symmetry, supercell unit-cell parameters, and details regarding the crystal structure are unknown. The strongest nine lines of the X-ray powder-diffraction pattern [d in A?? (I)(subcell hkl)] are: 5.413(30)(011), 4.063(80)(121), 3.201(50)(080), 3.023(50)(161), 2.983(60)(240), 2.858(30)(211), 2.765(50)(002), 2.518(100b)(091, 251) and 2.026(30)(242). The mineral is found in an isolated area measuring approximately 1 ?? 0.5 m in the lower level of the Perry pit, Mariposa mine, Terlingua mining district, Brewster County, Texas (type locality), as mm-sized anhedral dark orange to reddish orange crusts of variable thickness on calcite, and rarely as 0.5 mm-sized aggregates of crystals of the same color. It has also been identified at the McDermitt mine, Humboldt County, Nevada, U.S.A., where it occurs with kleinite and calomel in silicified volcanic rocks and sediments. Terlinguacreekite is a secondary phase, most probably formed from the alteration of primary cinnabar or native mercury. At Terlingua, most crusts are thin, almost cryptocrystalline, with no discernable forms, and are resinous and translucent to opaque. Crystals are up to 0.2 mm in length, subhedral, acicular to prismatic, elongation [001], with a maximum length-to-width ratio of 4:1. They are vitreous, transparent, and some crystals have brightly reflecting faces, which may be {010} and {110}. The streak is yellow, and the mineral is brittle with an uneven fracture, no observable cleavage, and is soft, nonfluorescent under both long- and short-wave ultraviolet light. D (calc.) is 9.899 g/cm3 (empirical formula). Material from the McDermitt mine is reversibly photosensitive, and turns from vivid orange to black in strong

Silver(I) complexes of the weakly coordinating solvents SO(2) and CH(2)Cl(2): crystal structures, bonding, and energetics of [Ag(OSO)][Al{OC(CF(3))(3)}(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(CH(2)Cl(2))(2)][SbF(6)].

Science.gov (United States)

Decken, Andreas; Knapp, Carsten; Nikiforov, Grigori B; Passmore, Jack; Rautiainen, J Mikko; Wang, Xinping; Zeng, Xiaoqing

2009-06-22

Pushing the limits of coordination chemistry: The most weakly coordinated silver complexes of the very weakly coordinating solvents dichloromethane and liquid sulfur dioxide were prepared. Special techniques at low temperatures and the use of weakly coordinating anions allowed structural characterization of [Ag(OSO)][Al{OC(CF(3))(3)}(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(Cl(2)CH(2))(2)][SbF(6)] (see figure). An investigation of the bonding shows that these complexes are mainly stabilized by electrostatic monopole-dipole interactions.The synthetically useful solvent-free silver(I) salt Ag[Al(pftb)(4)] (pftb=--OC(CF(3))(3)) was prepared by metathesis reaction of Li[Al(pftb)(4)] with Ag[SbF(6)] in liquid SO(2). The solvated complexes [Ag(OSO)][Al(pftb)(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(CH(2)Cl(2))(2)][SbF(6)] were prepared and isolated by special techniques at low temperatures and structurally characterized by single-crystal X-ray diffraction. The SO(2) complexes provide the first examples of coordination of the very weak Lewis base SO(2) to silver(I). The SO(2) molecule in [Ag(OSO)][Al(pftb)(4)] is eta(1)-O coordinated to Ag(+), while the SO(2) ligands in [Ag(OSO)(2/2)][SbF(6)] bridge two Ag(+) ions in an eta(2)-O,O' (trans,trans) manner. [Ag(CH(2)Cl(2))(2)][SbF(6)] contains [Ag(CH(2)Cl(2))(2)](+) ions linked through [SbF(6)](-) ions to give a polymeric structure. The solid-state silver(I) ion affinities (SIA) of SO(2) and CH(2)Cl(2), based on bond lengths and corresponding valence units in the corresponding complexes and tensimetric titrations of Ag[Al(pftb)(4)] and Ag[SbF(6)] with SO(2) vapor, show that SO(2) is a weaker ligand to Ag(+) than the commonly used weakly coordinating solvent CH(2)Cl(2) and indicated that binding strength of SO(2) to silver(I) in the silver(I) salts increases with increasing size of the corresponding counteranion ([Al(pftb)(4)](-)>[SbF(6)](-)). The experimental findings are in good agreement with theoretical gas-phase ligand

Syntheses, crystal structures and fluorescent properties of Cd(II), Hg(II) and Ag(I) coordination polymers constructed from 1H-1,2,4-triazole-1-acetic acid

International Nuclear Information System (INIS)

Ding Degang; Xie Lixia; Fan Yaoting; Hou Hongwei; Xu Yan

2009-01-01

Three new d 10 coordination polymers, namely [Cd(taa)Cl] n 1, [Hg(taa)Cl] n 2, and [Ag 1.5 (taa)(NO 3 ) 0.5 ] n 3 (taa=1H-1,2,4-triazole-1-acatate anion) have been prepared and characterized by elemental analysis, IR, and single crystal X-ray diffraction. Compound 1 consists of two-dimensional layers constructed by carboxyl-linked helical chains, which are further linked through carboxyl group to generate a unique 3D open framework. Topological analysis reveals that the structure of 1 can be classified as an unprecedented (3,8)-connected network with the Schlaefli symbol (4.5 2 ) 2 (4 2 .5 8 .6 14 .7 3 .8). Compound 2 manifests a doubly interpenetrated decorated α-polonium cubic network with the Schlaefli symbol of (4 10 .6 2 .8 3 ). Compound 3 consists of 2D puckered layers made up of Ag centers and taa - bridges. In addition, all of these compounds are photoluminescent in the solid state with spectra that closely resemble those of the ligand precursor. - Graphical abstract: Three new compounds based on 1H-1,2,4-triazole-1-acetic acid and Cd(II), Hg(II) and Ag(I) salts display luminescent properties and may be potential candidates for luminescent materials.

Prediction of the fate of Hg and other contaminants in soil around a former chlor-alkali plant using Fuzzy Hierarchical Cross-Clustering approach.

Science.gov (United States)

Frenţiu, Tiberiu; Ponta, Michaela; Sârbu, Costel

2015-11-01

An associative simultaneous fuzzy divisive hierarchical algorithm was used to predict the fate of Hg and other contaminants in soil around a former chlor-alkali plant. The algorithm was applied on several natural and anthropogenic characteristics of soil including water leachable, mobile, semi-mobile, non-mobile fractions and total Hg, Al, Ba, Ca, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Sr, Zn, water leachable fraction of Cl(-), NO3(-) and SO4(2)(-), pH and total organic carbon. The cross-classification algorithm provided a divisive fuzzy partition of the soil samples and associated characteristics. Soils outside the perimeter of the former chlor-alkali plant were clustered based on the natural characteristics and total Hg. In contaminated zones Hg speciation becomes relevant and the assessment of species distribution is necessary. The descending order of concentration of Hg species in the test site was semi-mobile>mobile>non-mobile>water-leachable. Physico-chemical features responsible for similarities or differences between uncontaminated soil samples or contaminated with Hg, Cu, Zn, Ba and NO3(-) were also highlighted. Other characteristics of the contaminated soil were found to be Ca, sulfate, Na and chloride, some of which with influence on Hg fate. The presence of Ca and sulfate in soil induced a higher water leachability of Hg, while Cu had an opposite effect by forming amalgam. The used algorithm provided an in-deep understanding of processes involving Hg species and allowed to make prediction of the fate of Hg and contaminants linked to chlor-alkali-industry. Copyright © 2015 Elsevier Ltd. All rights reserved.

Origin of the X-Hal (Hal = Cl, Br) bond-length change in the halogen-bonded complexes.

Science.gov (United States)

Wang, Weizhou; Hobza, Pavel

2008-05-01

The origin of the X-Hal bond-length change in the halogen bond of the X-Hal...Y type has been investigated at the MP2(full)/6-311++G(d,p) level of theory using a natural bond orbital analysis, atoms in molecules procedure, and electrostatic potential fitting methods. Our results have clearly shown that various theories explaining the nature of the hydrogen bond cannot be applied to explain the origin of the X-Hal bond-length change in the halogen bond. We provide a new explanation for this change. The elongation of the X-Hal bond length is caused by the electron-density transfer to the X-Hal sigma* antibonding orbital. For the blue-shifting halogen bond, the electron-density transfer to the X-Hal sigma* antibonding orbital is only of minor importance; it is the electrostatic attractive interaction that causes the X-Hal bond contraction.

Graphene Oxide Papers Simultaneously Doped with Mg(2+) and Cl(-) for Exceptional Mechanical, Electrical, and Dielectric Properties.

Science.gov (United States)

Lin, Xiuyi; Shen, Xi; Sun, Xinying; Liu, Xu; Wu, Ying; Wang, Zhenyu; Kim, Jang-Kyo

2016-01-27

This paper reports simultaneous modification of graphene oxide (GO) papers by functionalization with MgCl2. The Mg(2+) ions enhance both the interlayer cross-links and lateral bridging between the edges of adjacent GO sheets by forming Mg-O bonds. The improved load transfer between the GO sheets gives rise to a maximum of 200 and 400% increases in Young's modulus and tensile strength of GO papers. The intercalation of chlorine between the GO layers alters the properties of GO papers in two ways by forming ionic Cl(-) and covalent C-Cl bonds. The p-doping effect arising from Cl contributes to large enhancements in electrical conductivities of GO papers, with a remarkable 2500-fold surge in the through-thickness direction. The layered structure and the anisotropic electrical conductivities of reduced GO papers naturally create numerous nanocapacitors that lead to charge accumulation based on the Maxwell-Wagner (MW) polarization. The combined effect of much promoted dipolar polarizations due to Mg-O, C-Cl, and Cl(-) species results in an exceptionally high dielectric constant greater than 60 000 and a dielectric loss of 3 at 1 kHz by doping with 2 mM MgCl2. The excellent mechanical and electrical properties along with unique dielectric performance shown by the modified GO and rGO papers open new avenues for niche applications, such as electromagnetic interference shielding materials.

Social Capital and Unretirement: Exploring the Bonding, Bridging, and Linking Aspects of Social Relationships.

Science.gov (United States)

Gonzales, Ernest; Nowell, W Benjamin

2017-12-01

Working longer is an important area of research given extended life expectancy, shortfalls of retirement income, desires to remain socially engaged, and solvency concerns of social insurance programs. The purpose of this longitudinal population-based study of older adults is to examine how different types of social resources (social bonding, bridging, and linking) relate to returning to work after retirement. Data were drawn from the Health and Retirement Study of fully retired older adults aged 62+ in 1998 ( N = 8,334) and followed to 2008. After controlling for a comprehensive set of fixed and time-varying covariates, findings suggest that social bridging (informal volunteering) and social linking (formal volunteering, partnered with an employed spouse) were strongly and positively related to returning to work (Hazard Ratio [HR]: 1.49, p Social bonding resources were not significantly associated with returning to work. Implications for social policy are discussed.

College drinking behaviors: mediational links between parenting styles, parental bonds, depression, and alcohol problems.

Science.gov (United States)

Patock-Peckham, Julie A; Morgan-Lopez, Antonio A

2007-09-01

Mediational links between parenting styles (authoritative, authoritarian, permissive), parental bond (positive, negative), depression, alcohol use and abuse were tested. A 2-group, multiple-indicator, multiple-cause structural equation model with 441 (216 female, 225 male) college students was examined. In general, a poor parental bond with one's father was highly predictive of depression, a well-known predictor of alcohol abuse and related problems for both genders. In contrast, a positive parental bond with one's father significantly mediated the positive effects of authoritative fathering on depression, which then decreased alcohol use problems for both genders. For women, a negative parental bond with one's father significantly mediated the effect of having an authoritarian father on depression, which increased alcohol use problems. These findings suggest that parental influences on pathways to alcohol abuse through depression (primarily through fathers for both genders) are distinct from pathways stemming from poor impulse control (with influences primarily from the same-sex parents for both genders).

Synthesis of palm-based polyurethane-LiClO{sub 4} via prepolymerization

Energy Technology Data Exchange (ETDEWEB)

Sien, Jason Wong Chee [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi (Malaysia); School of Biosciences, Taylor’s University, Subang Jaya (Malaysia); Badri, Khairiah Haji [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi (Malaysia); Polymer Research Center, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi (Malaysia); Su’ait, Mohd Sukor [Polymer Research Center, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi (Malaysia); Solar Energy Research Institute Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi (Malaysia); Hassan, Nurul Izzati [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi (Malaysia)

2015-09-25

Palm-based polyurethane (pPU) with varying lithium salt (LiClO{sub 4}) content was synthesized. Higher loading percentage of LiClO{sub 4} in the pPU led to the inhibition of prepolymerization process from taking place. Hydrogen bonded C=O was detected in the FTIR spectrum indicating the hydrogen bonding between the urethane bonds. Ordered complexed C=O was observed in the FTIR spectrum confirming the complex formation between urethane bond and Li{sup +} ion. DSC thermogram showed the increase in the LiClO{sub 4} content could increase the glass transition temperature. SEM micrographs exhibited that more bubbles were formed when the LiClO{sub 4} increased from 10 to 30wt% indicating the reaction between free isocyanate groups with moisture presence in the salt due to the hygroscopic properties of LiClO{sub 4}.

Lasagna-type arrays with halide-nitromethane cluster filling. The first recognition of the Hal(-)···HCH2NO2 (Hal = Cl, Br, I) hydrogen bonding.

Science.gov (United States)

Gushchin, Pavel V; Kuznetsov, Maxim L; Wang, Qian; Karasik, Andrey A; Haukka, Matti; Starova, Galina L; Kukushkin, Vadim Yu

2012-06-21

The previously predicted ability of the methyl group of nitromethane to form hydrogen bonding with halides is now confirmed experimentally based on X-ray data of novel nitromethane solvates followed by theoretical ab initio calculations at the MP2 level of theory. The cationic (1,3,5-triazapentadiene)Pt(II) complexes [Pt{HN=C(NC(5)H(10))N(Ph)C(NH(2))=NPh}(2)](Cl)(2), [1](Hal)(2) (Hal = Cl, Br, I), and [Pt{HN=C(NC(4)H(8)O)N(Ph)C(NH(2))=NPh}(2)](Cl)(2), [2](Cl)(2), were crystallized from MeNO(2)-containing systems providing nitromethane solvates studied by X-ray diffraction. In the crystal structure of [1][(Hal)(2)(MeNO(2))(2)] (Hal = Cl, Br, I) and [2][(Cl)(2)(MeNO(2))(2)], the solvated MeNO(2) molecules occupy vacant spaces between lasagna-type layers and connect to the Hal(-) ion through a weak hydrogen bridge via the H atom of the methyl thus forming, by means of the Hal(-)···HCH(2)NO(2) contact, the halide-nitromethane cluster "filling". The quantum-chemical calculations demonstrated that the short distance between the Hal(-) anion and the hydrogen atom of nitromethane in clusters [1][(Hal)(2)(MeNO(2))(2)] and [2][(Cl)(2)(MeNO(2))(2)] is not just a consequence of the packing effect but a result of the moderately strong hydrogen bonding.

The crystal structure of TeCl3+AuCl4-

International Nuclear Information System (INIS)

Jones, P.G.; Jentsch, D.; Schwarzmann, E.

1986-01-01

TeCl 3 + AuCl 4 - crystallizes in the triclinic space group Panti 1 with a=7.564(2), b=7.720(3), c=8.964(3) A, α=78.26(3), β=88.84(3), γ=89.35(3) 0 , Z=2. The structure was refined to R 0.041 for 1380 reflections. The cation polyhedron, including secondary Te...Cl interactions, is a square pyramid with mean Te-Cl 2.294, Te...Cl 3.028 A. The secondary interactions link the ions to form centrosymmetric (TeCl 3 .AuCl 4 ) 2 dimers. (orig.)

Photoreduction of Hg(II) and photodemethylation of methylmercury: the key role of thiol sites on dissolved organic matter

Science.gov (United States)

Jeremiason, Jeffrey D.; Portner, Joshua C.; Aiken, George R.; Hiranaka, Amber J.; Dvorak, Michelle T.; Tran, Khuyen T.; Latch, Douglas E.

2015-01-01

This study examined the kinetics of photoreduction of Hg(II) and photodemethylation of methylmercury (MeHg+) attached to, or in the presence of, dissolved organic matter (DOM). Both Hg(II) and MeHg+ are principally bound to reduced sulfur groups associated with DOM in many freshwater systems. We propose that a direct photolysis mechanism is plausible for reduction of Hg(II) bound to reduced sulfur groups on DOM while an indirect mechanism is supported for photodemethylation of MeHg+ bound to DOM. UV spectra of Hg(II) and MeHg+ bound to thiol containing molecules demonstrate that the Hg(II)–S bond is capable of absorbing UV-light in the solar spectrum to a much greater extent than MeHg+–S bonds. Experiments with chemically distinct DOM isolates suggest that concentration of DOM matters little in the photochemistry if there are enough reduced S sites present to strongly bind MeHg+ and Hg(II); DOM concentration does not play a prominent role in photodemethylation other than to screen light, which was demonstrated in a field experiment in the highly colored St. Louis River where photodemethylation was not observed at depths ≥10 cm. Experiments with thiol ligands yielded slower photodegradation rates for MeHg+ than in experiments with DOM and thiols; rates in the presence of DOM alone were the fastest supporting an intra-DOM mechanism. Hg(II) photoreduction rates, however, were similar in experiments with only DOM, thiols plus DOM, or only thiols suggesting a direct photolysis mechanism. Quenching experiments also support the existence of an intra-DOM photodemethylation mechanism for MeHg+. Utilizing the difference in photodemethylation rates measured for MeHg+ attached to DOM or thiol ligands, the binding constant for MeHg+ attached to thiol groups on DOM was estimated to be 1016.7.

Surface reactivity of mercury on the oxygen-terminated hematite(0001) surface: a first-principle study

Science.gov (United States)

Jung, J. E.; Wilcox, J.

2016-12-01

Hematite (α-Fe2O3) is a common mineral found in Earth's near-surface environment. Due to its nontoxicity, corrosion-resistance, and high thermal stability, α-Fe2O3 has attracted attentions as materials for various applications such as photocatalysts, gas sensors, as well as for the removal of heavy metals. In this study, α-Fe2O3 is chosen for potential mercury (Hg) sorbent in order to remove Hg from coal-fired power plants. Specifically, theoretical approaches using density functional theory (DFT) is used to understand surface reactivity of Hg on oxygen (O) terminated α-Fe2O3(0001) surface. The most probable adsorption sites of Hg, chlorine (Cl), and mercury chloride (HgCl) on the α-Fe2O3 surface are found based on adsorption energy calculations, and the oxidation states of the adsorbates are determined by Bader charge analysis. Additionally, projected density of states (PDOS) analysis characterizes the surface-adsorbate bonding mechanism. The results of adsorption energy calculation proposes that Hg physisorbs to the α-Fe2O3(0001) surface with adsorption energy of -0.278 eV, and the subsequent Bader charge analysis confirms that Hg is slightly oxidized. In addition, Cl introduced to the Hg-adsorbed surface strengthens Hg stability on the α-Fe2O3(0001) surface as evidenced by a shortened Hg-surface equilibrium distance. The PDOS analysis also suggests that Cl enhances the chemical bonding between the surface and the adsorbate, thereby increasing adsorption strength. In summary, α-Fe2O3 has ability to adsorb and oxidize Hg, and this reactivity is enhanced in the presence of Cl.

Insertion reactions into Pd[bond]O and Pd[bond]N bonds: preparation of alkoxycarbonyl, carbonato, carbamato, thiocarbamate, and thioureide complexes of palladium(II).

Science.gov (United States)

Ruiz, José; Martínez, M Teresa; Florenciano, Félix; Rodríguez, Venancio; López, Gregorio; Pérez, José; Chaloner, Penny A; Hitchcock, Peter B

2003-06-02

Mononuclear palladium hydroxo complexes of the type [Pd(N[bond]N)(C(6)F(5))(OH)] [(N[bond]N = 2,2'-bipyridine (bipy), 4,4'-dimethyl-2,2'-bipyridine (Me(2)bipy), 1,10-phenanthroline (phen), or N,N,N',N'-tetramethylethylenediamine (tmeda)] have been prepared by reaction of [Pd(N[bond]N)(C(6)F(5))(acetone)]ClO(4) with KOH in methanol. These hydroxo complexes react, in methanol, with CO (1 atm, room temperature) to yield the corresponding methoxycarbonyl complexes [Pd(N[bond]N)(C(6)F(5))(CO(2)Me)]. Similar alkoxycarbonyl complexes [Pd(N[bond]N)(C(6)F(5))(CO(2)R)] (N[bond]N = bis(3,5-dimethylpyrazol-1-yl)methane); R = Me, Et, or (i)Pr) are obtained when [Pd(N[bond]N)(C(6)F(5))Cl] is treated with KOH in the corresponding alcohol ROH and CO is bubbled through the solution. The reactions of [Pd(N[bond]N)(C(6)F(5))(OH)] (N[bond]N = bipy or Me(2)bipy) with CO(2), in tetrahydrofuran, lead to the formation of the binuclear carbonate complexes [(N[bond]N)(C(6)F(5))Pd(mu-eta(2)-CO(3))Pd(C(6)F(5))(N[bond]N)]. Complexes [Pd(N[bond]N)(C(6)F(5))(OH)] react in alcohol with PhNCS to yield the corresponding N-phenyl-O-alkylthiocarbamate complexes [Pd(N[bond]N)(C(6)F(5))[SC(OR)NPh

Crystal structure of dichloridobis(N,N′-dimethylthiourea-κSmercury(II

Directory of Open Access Journals (Sweden)

Muhammad Ashraf Shaheen

2015-09-01

Full Text Available The molecular structure of the title compound, [HgCl2(C3H8N2S2], has point group symmetry 2, with the twofold rotation axis passing through the HgII atom. The latter is coordinated by two Cl atoms and two N,N′-dimethylthiourea (Dmtu ligands through their S atoms, defining a distorted tetrahedral coordination sphere with bond angles in the range 102.47 (4–118.32 (4°. Intra- and intermolecular hydrogen bonds of the type N—H...Cl with S(6 and R22(12 ring motifs are present. The intermolecular contacts make up polymeric chains extending parallel to [101].

A fluorescent DNA based probe for Hg(II) based on thymine-Hg(II)-thymine interaction and enrichment via magnetized graphene oxide.

Science.gov (United States)

Li, Meng-Ke; Hu, Liu-Yin; Niu, Cheng-Gang; Huang, Da-Wei; Zeng, Guang-Ming

2018-03-03

The authors describe a fluorometric assay for the determination of Hg(II). A naphthalimide derivative is used as a label for a thymine (T) rich ssDNA, and graphene oxide magnetized with Fe 3 O 4 nanoparticles acts as a quencher and preconcentrators. In the absence of Hg(II), the labeled ssDNA does not separate from the magnetized graphene oxide. As a result, fluorescence is fully quenched. In the presence of Hg(II), a T-Hg(II)-T link is formed dues to the highly affinity between T and Hg(II). Hence, fluorescence is restored. The assay has a linear response in the 1.0 to 10.0 nM Hg(II) concentration range, and a 0.65 nM detection limit. The method is selective and sensitive. It was applied to the analysis of spiked environmental water samples, and data agreed well with those obtained by atomic fluorescence spectrometry. Graphical abstract Strategy of a fluorescent probe for detecting Hg(II). The method has a 0.65 nM detection limit and is selective. MGO: magnetized graphene oxide, AHN: a fluorescent derivative of naphthalimide.

Vapour pressure of components made by the presence of HgS(s,alpha) in an oil/gas reservoir and consequences for the produced gas

Energy Technology Data Exchange (ETDEWEB)

Oestvold, T.; Gustavsen, Oe.; Grande, K.; Aas, N.; Olsvik, Mimmi Kjetsaa

2006-03-15

A thermodynamic analysis is presented on how components made from HgS (s,alpha), existing in a oil/gas reservoir, will distribute themselves between gas, water, liquid and solid components as a function of temperature and pressure. The consequence of the formation of mercury containing components on gas injection and on gas quality is discussed. Since equilibrium is established in the model calculation, other gas components in the gas phase and components in condensed phases present will also influence the composition of the gas. Six cases are considered in the calculation: 1) HgS(s,alpha) - Ar(g), 2) HgS(s,alpha) - Ar (g) - water with 10-4 molal NaCl at pH = 7, 3) HgS(s,alpha) - CH{sub 4}(g), 4) HgS(s,alpha) - CH{sub 4} (g) - water with 10-4 molal NaCl at pH = 7 and 5) HgS(s,alpha) - natural gas - water with 10-4 molal NaCl at pH = 7, 6) HgS(s,alpha) - natural gas - water with 10-4 molal NaCl and 5*10-5 molal NO-3- at pH = 7. When HgS(s,alpha) is present in an oil reservoir at 170 deg C and 200 bar, these calculations show that the major components formed are: H{sub 2}(g), H{sub 2}S(g), Hg(l) and Hg(g) together with carbon. Mercury in the gas phase in the cases 1) is 4*10-7 bar and is determined by the evaporation and decomposition HgS(g) in the reservoir. In case 2) P{sub Hg} = 5.7*10-4 bar mainly determined by the formation of sulphate in the water phase. In the cases 3), 4) and 5) these calculations show that the major components formed are: H{sub 2}(g), H{sub 2}S(g), Hg(l) and Hg(g) together with carbon, and the gas phase is dominated by Hg(g) at approx. *10-3 bar. The water phase may contain Hg(CH{sub 3}NH{sub 2}){sub 2}2+ if NO{sub 3}- for some reasons is introduced into the formation water, and the very carcinogenic dimethyl mercury compound, C{sub 2}HgH{sub 6}, can be formed in the gas phase. Both compounds, however, in insignificant low concentration/partial pressure. (Author)

Bonding, Bridging, and Linking Social Capital and Self-Rated Health among Chinese Adults: Use of the Anchoring Vignettes Technique.

Directory of Open Access Journals (Sweden)

He Chen

Full Text Available Three main opposing camps exist over how social capital relates to population health, namely the social support perspective, the inequality thesis, and the political economy approach. The distinction among bonding, bridging, and linking social capital probably helps close the debates between these three camps, which is rarely investigated in existing literatures. Moreover, although self-rated health is a frequently used health indicator in studies on the relationship between social capital and health, the interpersonal incomparability of this measure has been largely neglected. This study has two main objectives. Firstly, we aim to investigate the relationship between bonding, bridging, and linking social capital and self-rated health among Chinese adults. Secondly, we aim to improve the interpersonal comparability in self-rated health measurement. We use data from a nationally representative survey in China. Self-rated health was adjusted using the anchoring vignettes technique to improve comparability. Two-level ordinal logistic regression was performed to model the association between social capital and self-rated health at both individual and community levels. The interaction between residence and social capital was included to examine urban/rural disparities in the relationship. We found that most social capital indicators had a significant relationship with adjusted self-rated health of Chinese adults, but the relationships were mixed. Individual-level bonding, linking social capital, and community-level bridging social capital were positively related with health. Significant urban/rural disparities appeared in the association between community-level bonding, linking social capital, and adjusted self-rated health. For example, people living in communities with higher bonding social capital tended to report poorer adjusted self-rated health in urban areas, but the opposite tendency held for rural areas. Furthermore, the comparison between

Bonding, Bridging, and Linking Social Capital and Self-Rated Health among Chinese Adults: Use of the Anchoring Vignettes Technique.

Science.gov (United States)

Chen, He; Meng, Tianguang

2015-01-01

Three main opposing camps exist over how social capital relates to population health, namely the social support perspective, the inequality thesis, and the political economy approach. The distinction among bonding, bridging, and linking social capital probably helps close the debates between these three camps, which is rarely investigated in existing literatures. Moreover, although self-rated health is a frequently used health indicator in studies on the relationship between social capital and health, the interpersonal incomparability of this measure has been largely neglected. This study has two main objectives. Firstly, we aim to investigate the relationship between bonding, bridging, and linking social capital and self-rated health among Chinese adults. Secondly, we aim to improve the interpersonal comparability in self-rated health measurement. We use data from a nationally representative survey in China. Self-rated health was adjusted using the anchoring vignettes technique to improve comparability. Two-level ordinal logistic regression was performed to model the association between social capital and self-rated health at both individual and community levels. The interaction between residence and social capital was included to examine urban/rural disparities in the relationship. We found that most social capital indicators had a significant relationship with adjusted self-rated health of Chinese adults, but the relationships were mixed. Individual-level bonding, linking social capital, and community-level bridging social capital were positively related with health. Significant urban/rural disparities appeared in the association between community-level bonding, linking social capital, and adjusted self-rated health. For example, people living in communities with higher bonding social capital tended to report poorer adjusted self-rated health in urban areas, but the opposite tendency held for rural areas. Furthermore, the comparison between multivariate analyses

Study of the odd mass transition nuclei: 185Hg, 187Hg, 189Hg and 183Ir

International Nuclear Information System (INIS)

Zerrouki, A.

1979-01-01

The radioactive decay of 185 Tl, 186 Tl, 187 Tl has been studied on the isotope separator Isocele II working on line with the Orsay synchrocyclotron from Au( 3 He,xn) reactions: the emitted α lines have been measured and the main γ lines belonging to the 187 Tl→ 187 Hg decay have been identified. The 185 Hg, 187 Hg, 189 Hg high spin states have been studied using the following (HI,xn) reactions obtained on the Strasbourg MP Tandem: 168 Er( 24 Mg,xn) 187 Hg, 188 Hg, 166 Er( 24 Mg,xn) 185 Hg, 186 Hg, 157 Gd( 32 S,xn) 184 Hg, 185 Hg, 158 Gd( 32 S,5n) 185 Hg and 175 Lu( 19 F,5n) 189 Hg. The excitation functions are indicated and a high spin level scheme of 189 Hg is proposed: it is compared to the 'quasiparticle + triaxial rotor' model predictions. A level scheme of 183 Ir is proposed from the data collected at Isolde II (CERN) by Dr. SCHUCK: it is analysed within the framework of the same theoretical model used above [fr

Early Hg mobility in cultivated tropical soils one year after slash-and-burn of the primary forest, in the Brazilian Amazon.

Science.gov (United States)

Béliveau, Annie; Lucotte, Marc; Davidson, Robert; Lopes, Luis Otávio do Canto; Paquet, Serge

2009-07-15

In the Brazilian Amazon, forest conversion to agricultural lands (slash-and-burn cultivation) contributes to soil mercury (Hg) release and to aquatic ecosystem contamination. Recent studies have shown that soil Hg loss occurs rapidly after deforestation, suggesting that Hg mobility could be related to the massive cation input resulting from biomass burning. The objective of this research was to determine the effects of the first year of slash-and-burn agriculture on soil Hg levels at the regional scale of the Tapajós River, in the state of Pará, Brazilian Amazon. A total of 429 soil samples were collected in 26 farms of five riparian communities of the Tapajós basin. In September 2004, soil samples were collected from primary forest sites planned for slash-and-burn cultivation. In August 2005, one year after the initial burning, a second campaign was held and the exact same sites were re-sampled. Our results showed that total Hg levels in soils did not change significantly during the first year following slash-and-burn, suggesting no immediate release of soil Hg at that point in time. However, an early Hg mobility was detected near the surface (0-5 cm), reflected by a significant shift in Hg distribution in soil fractions. Indeed, a transfer of Hg from fine to coarser soil particles was observed, indicating that chemical bonds between Hg and fine particles could have been altered. A correspondence analysis (CA) showed that this process could be linked to a chemical competition caused by cation enrichment. The regional dimension of the study highlighted the prevailing importance of soil types in Hg dynamics, as shown by differentiated soil responses following deforestation according to soil texture. Confirming an early Hg mobility and indicating an eventual Hg release out of the soil, our results reinforce the call for the development of more sustainable agricultural practices in the Amazon.

AcEST: CL1889Contig1 [AcEST

Lifescience Database Archive (English)

Full Text Available CL1889Contig1 491 2 Adiantum capillus-veneris contig: CL1889contig1 sequence. Link ...apillus-veneris contig: CL1889contig1 sequence. Link to clone list Link to clone list Clone ID BP919609 BP91

Reprocessing and Recycling of Highly Cross-Linked Ion-Conducting Networks through Transalkylation Exchanges of C-N Bonds.

Science.gov (United States)

Obadia, Mona M; Mudraboyina, Bhanu P; Serghei, Anatoli; Montarnal, Damien; Drockenmuller, Eric

2015-05-13

Exploiting exchangeable covalent bonds as dynamic cross-links recently afforded a new class of polymer materials coined as vitrimers. These permanent networks are insoluble and infusible, but the network topology can be reshuffled at high temperatures, thus enabling glasslike plastic deformation and reprocessing without depolymerization. We disclose herein the development of functional and high-value ion-conducting vitrimers that take inspiration from poly(ionic liquid)s. Tunable networks with high ionic content are obtained by the solvent- and catalyst-free polyaddition of an α-azide-ω-alkyne monomer and simultaneous alkylation of the resulting poly(1,2,3-triazole)s with a series of difunctional cross-linking agents. Temperature-induced transalkylation exchanges of C-N bonds between 1,2,3-triazolium cross-links and halide-functionalized dangling chains enable recycling and reprocessing of these highly cross-linked permanent networks. They can also be recycled by depolymerization with specific solvents able to displace the transalkylation equilibrium, and they display a great potential for applications that require solid electrolytes with excellent mechanical performances and facile processing such as supercapacitors, batteries, fuel cells, and separation membranes.

Comparison of gaseous oxidized Hg measured by KCl-coated denuders, and nylon and cation exchange membranes.

Science.gov (United States)

Huang, Jiaoyan; Miller, Matthieu B; Weiss-Penzias, Peter; Gustin, Mae Sexauer

2013-07-02

The chemical compounds that make up gaseous oxidized mercury (GOM) in the atmosphere, and the reactions responsible for their formation, are not well understood. The limitations and uncertainties associated with the current method applied to measure these compounds, the KCl-coated denuder, are not known due to lack of calibration and testing. This study systematically compared the uptake of specific GOM compounds by KCl-coated denuders with that collected using nylon and cation exchange membranes in the laboratory and field. In addition, a new method for identifying different GOM compounds using thermal desorption is presented. Different GOM compounds (HgCl2, HgBr2, and HgO) were found to have different affinities for the denuder surface and the denuder underestimated each of these compounds. Membranes measured 1.3 to 3.7 times higher GOM than denuders in laboratory and field experiments. Cation exchange membranes had the highest collection efficiency. Thermodesorption profiles for the release of GOM compounds from the nylon membrane were different for HgO versus HgBr2 and HgCl2. Application of the new field method for collection and identification of GOM compounds demonstrated these vary as a function of location and time of year. Understanding the chemistry of GOM across space and time has important implications for those developing policy regarding this environmental contaminant.

Nucleophilicities of Lewis Bases B and Electrophilicities of Lewis Acids A Determined from the Dissociation Energies of Complexes B⋯A Involving Hydrogen Bonds, Tetrel Bonds, Pnictogen Bonds, Chalcogen Bonds and Halogen Bonds

Directory of Open Access Journals (Sweden)

Ibon Alkorta

2017-10-01

Full Text Available It is shown that the dissociation energy D e for the process B⋯A = B + A for 250 complexes B⋯A composed of 11 Lewis bases B (N2, CO, HC≡CH, CH2=CH2, C3H6, PH3, H2S, HCN, H2O, H2CO and NH3 and 23 Lewis acids (HF, HCl, HBr, HC≡CH, HCN, H2O, F2, Cl2, Br2, ClF, BrCl, H3SiF, H3GeF, F2CO, CO2, N2O, NO2F, PH2F, AsH2F, SO2, SeO2, SF2, and SeF2 can be represented to good approximation by means of the equation D e = c ′ N B E A , in which N B is a numerical nucleophilicity assigned to B, E A is a numerical electrophilicity assigned to A, and c ′ is a constant, conveniently chosen to have the value 1.00 kJ mol−1 here. The 250 complexes were chosen to cover a wide range of non-covalent interaction types, namely: (1 the hydrogen bond; (2 the halogen bond; (3 the tetrel bond; (4 the pnictogen bond; and (5 the chalcogen bond. Since there is no evidence that one group of non-covalent interaction was fitted any better than the others, it appears the equation is equally valid for all the interactions considered and that the values of N B and E A so determined define properties of the individual molecules. The values of N B and E A can be used to predict the dissociation energies of a wide range of binary complexes B⋯A with reasonable accuracy.

Antagonistic Growth Effects of Mercury and Selenium in Caenorhabditis elegans Are Chemical-Species-Dependent and Do Not Depend on Internal Hg/Se Ratios.

Science.gov (United States)

Wyatt, Lauren H; Diringer, Sarah E; Rogers, Laura A; Hsu-Kim, Heileen; Pan, William K; Meyer, Joel N

2016-03-15

The relationship between mercury (Hg) and selenium (Se) toxicity is complex, with coexposure reported to reduce, increase, and have no effect on toxicity. Different interactions may be related to chemical compound, but this has not been systematically examined. Our goal was to assess the interactive effects between the two elements on growth in the nematode Caenorhabditis elegans, focusing on inorganic and organic Hg (HgCl2 and MeHgCl) and Se (selenomethionine, sodium selenite, and sodium selenate) compounds. We utilized aqueous Hg/Se dosing molar ratios that were either above, below, or equal to 1 and measured the internal nematode total Hg and Se concentrations for the highest concentrations of each Se compound. Observed interactions were complicated, differed between Se and Hg compounds, and included greater-than-additive, additive, and less-than-additive growth impacts. Biologically significant interactions were only observed when the dosing Se solution concentration was 100-25,000 times greater than the dosing Hg concentration. Mitigation of growth impacts was not predictable on the basis of internal Hg/Se molar ratio; improved growth was observed at some internal Hg/Se molar ratios both above and below 1. These findings suggest that future assessments of the Hg and Se relationship should incorporate chemical compound into the evaluation.

Recycling of rare earths from Hg-containing fluorescent lamp scraps by solid state chlorination

International Nuclear Information System (INIS)

Lorenz, Tom; Froehlich, Peter; Bertau, Martin; Golon, Katja

2015-01-01

Solid state chlorination with NH 4 Cl comprises a method for rare earth recycling apart from pyro- or hydrometallurgical strategies. The examined partially Hg-containing fluorescent lamp scraps are rich in rare earths like La, Ce, Tb and Gd, but especially in Y and Eu. By mixing with NH 4 Cl and heating up to NH 4 Cl decomposition temperature in a sublimation reactor, Y and Eu could be transferred selectively into their respective metal chlorides with high yields. The yield and selectivity depend on temperature and the ratio of NH 4 Cl to fluorescent lamp scraps, which were varied systematically.

Bonding in scandium monosulfide a NaCl crystal type

International Nuclear Information System (INIS)

Merrick, J.A.

1980-08-01

The transition temperature of an order-disorder transition in Sc 0 81 S (R anti 3m to Fm3m) occurs at 700 0 C. A group of ordered sublattices on the NaCl-type lattice (Fm3m) was generated and a Madelung energy and configurational entropy were calculated for each sublattice assuming the ions to be Sc 2 48+ and S 2- . Mean field and pair interaction approximations were used to model long-range and short-range orderings, respectively. The electrostatic model fails to predict the observed short-range and long-range orderings. The high temperature vaporization of ScP was investigated by mass spectrometry and target collection Knudsen effusion at 1767 to 2209K. The composition ScP 1 00 vaporizes congruently to the gaseous species Sc, P, and P 2 . A temperature independent third law enthalpy of atomization (ΔH 0 /sub atom,298/ = 252.2 +- 2.8 kcal mole -1 ) has a value approx. 12 kcal larger than that reported for ScS. Nonrelativistic, nonself-consistent LAPW band structure calculations are reported for ScS. XPS and UPS measurements are reported for Sc 2 S 3 and several compositions Sc/sub 1-x/S (0.0 less than or equal to x less than or equal to 0.2). The Sc and S 2p binding energies (XPS) obtained for the defect scandium monosulfides are very close to those found in the pure elements, suggesting covalent bonding. The Sc 2p energy region has an interesting satellite structure

Dose and time relations in Hg(++)-induced tubular necrosis and regeneration

DEFF Research Database (Denmark)

Nielsen, J B; Andersen, H R; Andersen, O

1994-01-01

relationship is caused by a dose-related induction of kidney damage leading to increasing leakage of mercury through the kidneys. Histopathologic investigation revealed extensive necrosis of the proximal tubules in kidneys from mice exposed to 100 mumole HgCl2/kg or higher doses. Moreover, maximum renal damage...

Phonons and their dispersion in model ferroelastics Hg2Hal2

Science.gov (United States)

Roginskii, E. M.; Kvasov, A. A.; Markov, Yu. F.; Smirnov, M. B.

2012-05-01

Dispersion relations of the acoustic and optical phonon frequencies have been calculated and plotted, and the density of states of the phonon spectrum of Hg2Cl2 and Hg2Br2 crystals has been derived. The effect of hydrostatic pressure on the frequencies of acoustic and optical phonons and their dispersion has been theoretically analyzed. It has been found that an increase in the pressure leads to a strong softening of the slowest acoustic TA branch (the soft mode) at the X point of the Brillouin zone boundary, which is consistent with the phenomenological Landau theory and correlates with experiment.

Synthesis and structures of six closely related N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]arylamides, together with an isolated reaction intermediate: order versus disorder, molecular conformations and hydrogen bonding in zero, one and two dimensions.

Science.gov (United States)

Sagar, Belakavadi K; Yathirajan, Hemmige S; Rathore, Ravindranath S; Glidewell, Christopher

2018-02-01

Six closely related N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]arylamides have been synthesized and structurally characterized, together with a representative reaction intermediate. In each of N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]benzamide, C 20 H 16 ClNO 2 S, (I), N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]-4-phenylbenzamide, C 26 H 20 ClNO 2 S, (II), and 2-bromo-N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]benzamide, C 20 H 15 BrClNO 2 S, (III), the molecules are disordered over two sets of atomic sites, with occupancies of 0.894 (8) and 0.106 (8) in (I), 0.832 (5) and 0.168 (5) in (II), and 0.7006 (12) and 0.2994 (12) in (III). In each of N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]-2-iodobenzamide, C 20 H 15 ClINO 2 S, (IV), and N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]-2-methoxybenzamide, C 21 H 18 ClNO 3 S, (V), the molecules are fully ordered, but in N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]-2,6-difluorobenzamide, C 20 H 14 ClF 2 NO 2 S, (VI), which crystallizes with Z' = 2 in the space group C2/c, one of the two independent molecules is fully ordered, while the other is disordered over two sets of atomic sites having occupancies of 0.916 (3) and 0.084 (3). All of the molecules in compounds (I)-(VI) exhibit an intramolecular N-H...O hydrogen bond. The molecules of (I) and (VI) are linked by C-H...O hydrogen bonds to form finite zero-dimensional dimers, which are cyclic in (I) and acyclic in (VI), those of (III) are linked by C-H...π(arene) hydrogen bonds to form simple chains, and those of (IV) and (V) are linked into different types of chains of rings, built in each case from a combination of C-H...O and C-H...π(arene) hydrogen bonds. Two C-H...O hydrogen bonds link the molecules of (II) into sheets containing three types of ring. In benzotriazol-1-yl 3,4-dimethoxybenzoate, C 15 H 13 N 3 O 4 , (VII), the benzoate component is planar and makes a dihedral angle of 84.51 (6)° with the benzotriazole unit. Comparisons are made

Intense charge transfer surface based on graphene and thymine-Hg(II)-thymine base pairs for detection of Hg(2.).

Science.gov (United States)

Li, Jiao; Lu, Liping; Kang, Tianfang; Cheng, Shuiyuan

2016-03-15

In this article, we developed an electrochemiluminescence (ECL) sensor with a high-intensity charge transfer interface for Hg(2+) detection based on Hg(II)-induced DNA hybridization. The sensor was fabricated by the following simple method. First, graphene oxide (GO) was electrochemically reduced onto a glassy carbon electrode through cyclic voltammetry. Then, amino-labeled double-stranded (ds)DNA was assembled on the electrode surface using 1-pyrenebutyric acid N-hydroxysuccinimide as a linker between GO and DNA. The other terminal of dsDNA, which was labeled with biotin, was linked to CdSe quantum dots via biotin-avidin interactions. Reduced graphene oxide has excellent electrical conductivity. dsDNA with T-Hg(II)-T base pairs exhibited more facile charge transfer. They both accelerate the electron transfer performance and sensitivity of the sensor. The increased ECL signals were logarithmically linear with the concentration of Hg(II) when Hg(2+) was present in the detection solution. The linear range of the sensor was 10(-11) to 10(-8)mol/L (R=0.9819) with a detection limit of 10(-11)mol/L. This biosensor exhibited satisfactory results when it was used to detect Hg(II) in real water samples. The biosensor with high-intense charge transfer performance is a prospect avenue to pursue more and more sensitive detection method. Copyright © 2015 Elsevier B.V. All rights reserved.

New compounds bearing [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} anions (M = Si, Ge, Sn): Syntheses and characterization of A{sub 2}[Si(S{sub 2}O{sub 7}){sub 3}] (A = Na, K, Rb), A{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}] (A = Li, Na, K, Rb, Cs), A{sub 2}[Sn(S{sub 2}O{sub 7}){sub 3}] (A = Na, K), and the unique germanate Hg{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}]Cl{sub 2} with cationic {sup 1}{sub ∞}[HgCl{sub 2/2}]{sup +} chains

Energy Technology Data Exchange (ETDEWEB)

Logemann, Christian; Witt, Julia; Wickleder, Mathias S. [Universitaet Oldenburg, Institut fuer Reine und Angewandte Chemie (Germany); Gunzelmann, Daniel; Senker, Juergen [Universitaet Bayreuth, Lehrstuhl fuer Anorganische Chemie III (Germany)

2012-10-15

The reaction of the group 14 tetrachlorides MCl{sub 4} (M = Si, Ge, Sn) with oleum (65 % SO{sub 3}) at elevated temperatures led to the unique anionic complexes [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} that show the central M atoms in coordination of three chelating S{sub 2}O{sub 7}{sup 2-} groups. The mean distances M-O within the complexes increase from 175 pm (M = Si) via 186 pm (M = Ge) up to 200 pm (M = Sn). The charge balance for the [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} anions is achieved by alkaline metal ions A{sup +} (A = Li, Na, K, Rb, Cs) which were implemented in the syntheses in form of their sulfates. The size of the A{sup +} ions, i.e. their coordination requirement causes the crystallographic differences in the crystal structures, while the structure of the complex [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} anions remains essentially unaffected. Furthermore, we were able to characterize the unique germanate Hg{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}]Cl{sub 2} which forms when HgCl{sub 2} is added as a source for the counter cation. The Hg{sup 2+} and the Cl{sup -} ions form infinite cationic chains according to {sup 1}{sub ∞}[HgCl{sub 2/2}]{sup +} which take care for the charge compensation. For selected examples of the compounds the thermal behavior has been monitored by means of thermal analyses and X-ray powder diffraction. For A being an alkaline metal the decomposition product is a mixture of the sulfates A{sub 2}SO{sub 4} and the dioxides MO{sub 2}, whereas Hg{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}]Cl{sub 2} shows a more complicated decomposition. The tris-(disulfato)-silicate Na{sub 2}[Si(S{sub 2}O{sub 7}){sub 3}] has additionally been examined by solid state {sup 29}Si and {sup 23}Na NMR spectroscopic measurements. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Extended x-ray absorption fine structure study of arsenic in HgCdTe: p-type doping linked to nonsubstitutional As incorporation in an unknown AsHg8 structure

International Nuclear Information System (INIS)

Biquard, X.; Alliot, I.; Ballet, P.

2009-01-01

An extended x-ray absorption fine structure (EXAFS) investigation has been carried out on arsenic-doped Hg 70 Cd 30 Te samples. The incorporation of atomic arsenic has been achieved using a nonconventional radio-frequency plasma source in a molecular beam epitaxy reactor. Two samples from the same epitaxial wafer have been studied. One underwent a 400 deg. C activation annealing under Hg pressure, leading to n to p-type conversion. In the commonly admitted scenario, this conversion is associated with the annealing-induced migration of As from a Hg site to a Te site. This study shows that this is not the case. Before annealing, As is found to be involved in noncrystalline structures: 50% inside an As 2 Te 3 chalcogenide glass and 50% inside a new AsHg 8 compact structure. After annealing, the As 2 Te 3 chalcogenide glass disappears, 31% of As occupies Hg sites and 69% incorporates inside this new AsHg 8 compact structure that occupies Te sites. The EXAFS results are in excellent agreement with 77 K Hall-effect measurements. The new AsHg 8 structure is found to have an acceptor behavior. Overall, this study provides an entirely new vision of extrinsic p-type doping of HgCdTe as well as the first experimental evidence of As site transfer induced by annealing.

Dichloridobis(N,N,N′,N′-tetramethylthiourea-κSmercury(II

Directory of Open Access Journals (Sweden)

Sidra Nawaz

2010-08-01

Full Text Available In the title compound, [HgCl2(C5H12N2S2], the HgII atom is located on a twofold rotation axis and is bonded in a distorted tetrahedral coordination mode to two chloride ions and to two tetramethylthiourea (tmtu molecules through their S atoms. The crystal structure is stabilized by C—H...N and C—H...S hydrogen bonds.

Comparison of effects of ATP-MgCl2 and adenosine-MgCl2 on renal function following ischemia

International Nuclear Information System (INIS)

Sumpio, B.E.; Hull, M.J.; Baue, A.E.; Chaudry, I.H.

1987-01-01

ATO-MgCl 2 administration had been shown to accelerate the recovery of renal function following warm ischemia. However, since the major breakdown product of ATP is adenosine, the relative contribution of ATP vs. adenosine in improving renal function following ischemia remains to be determined. To study this, kidneys were subjected to 45 min of normothermic ischemia and then perfused at 100 mmHg with oxygenated Krebs-HCO 3 buffer containing albumin, [ 3 H]inulin, substrates, and either 0.3 mM ATP-MgCl 2 or adenosine-MgCl 2 for 110 min. Perfusate and timed urine samples were collected and analyzed for radioactivity and [Na + ]. The functional parameters indicated that although adenosine-MgCl 2 treatment provided a transient improvement, it failed to provided a sustained improvement in renal function or attain control valued compared with ATP-MgCl 2 treatment. Thus, the salutary effects of ATP-MgCl 2 following warm ischemia in the kidney are not mediated by adenosine

Interplay between structure and transport properties of molten salt mixtures of ZnCl2-NaCl-KCl: A molecular dynamics study.

Science.gov (United States)

Manga, Venkateswara Rao; Swinteck, Nichlas; Bringuier, Stefan; Lucas, Pierre; Deymier, Pierre; Muralidharan, Krishna

2016-03-07

Molten mixtures of network-forming covalently bonded ZnCl2 and network-modifying ionically bonded NaCl and KCl salts are investigated as high-temperature heat transfer fluids for concentrating solar power plants. Specifically, using molecular dynamics simulations, the interplay between the extent of the network structure, composition, and the transport properties (viscosity, thermal conductivity, and diffusion) of ZnCl2-NaCl-KCl molten salts is characterized. The Stokes-Einstein/Eyring relationship is found to break down in these network-forming liquids at high concentrations of ZnCl2 (>63 mol. %), while the Eyring relationship is seen with increasing KCl concentration. Further, the network modification due to the addition of K ions leads to formation of non-bridging terminal Cl ions, which in turn lead to a positive temperature dependence of thermal conductivity in these melts. This new understanding of transport in these ternary liquids enables the identification of appropriate concentrations of the network formers and network modifiers to design heat transfer fluids with desired transport properties for concentrating solar power plants.

Methylation of Hg downstream from the Bonanza Hg mine, Oregon

Science.gov (United States)

Gray, John E.; Hines, Mark E.; Krabbenhoft, David P.; Thoms, Bryn

2012-01-01

Speciation of Hg and conversion to methyl-Hg were evaluated in stream sediment, stream water, and aquatic snails collected downstream from the Bonanza Hg mine, Oregon. Total production from the Bonanza mine was >1360t of Hg, during mining from the late 1800s to 1960, ranking it as an intermediate sized Hg mine on an international scale. The primary objective of this study was to evaluate the distribution, transport, and methylation of Hg downstream from a Hg mine in a coastal temperate climatic zone. Data shown here for methyl-Hg, a neurotoxin hazardous to humans, are the first reported for sediment and water from this area. Stream sediment collected from Foster Creek flowing downstream from the Bonanza mine contained elevated Hg concentrations that ranged from 590 to 71,000ng/g, all of which (except the most distal sample) exceeded the probable effect concentration (PEC) of 1060ng/g, the Hg concentration above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in stream sediment collected from Foster Creek varied from 11 to 62ng/g and were highly elevated compared to regional baseline concentrations (0.11-0.82ng/g) established in this study. Methyl-Hg concentrations in stream sediment collected in this study showed a significant correlation with total organic C (TOC, R2=0.62), generally indicating increased methyl-Hg formation with increasing TOC in sediment. Isotopic-tracer methods indicated that several samples of Foster Creek sediment exhibited high rates of Hg-methylation. Concentrations of Hg in water collected downstream from the mine varied from 17 to 270ng/L and were also elevated compared to baselines, but all were below the 770ng/L Hg standard recommended by the USEPA to protect against chronic effects to aquatic wildlife. Concentrations of methyl-Hg in the water collected from Foster Creek ranged from 0.17 to 1.8ng/L, which were elevated compared to regional baseline sites upstream and downstream

Strength order and nature of the π-hole bond of cyanuric chloride and 1,3,5-triazine with halide.

Science.gov (United States)

Wang, Hui; Li, Chen; Wang, Weizhou; Jin, Wei Jun

2015-08-28

The (13)C NMR chemical shift moving upfield indicates the main model of π-holeX(-) bond between cyanuric chloride/1,3,5-triazine (3ClN/3N), which possess both the π-hole and σ-hole, and X(-). (13)C NMR and UV absorption titration in acetonitrile confirmed that the bonding abilities of 3ClN/3N with X(-) follow the order I(-) > Br(-) > Cl(-), which is apparently the order of the charge transfer ability of halide to 3ClN/3N. Chemical calculations showed that the bonding abilities in solution were essentially consistent with those obtained by titration experiments. However, the results in the gas phase were the reverse, i.e., π-holeCl(-) > π-holeBr(-) > π-holeI(-) in bonding energy, which obeys the order of electrostatic interaction. In fact, the π-hole bond and σ-hole bond compete with solvation and possible anion-hydrogen bond between a solvent molecule and a halide in solution. An explanation is that the apparent charge transfer order of π-/σ-holeI(-) > π-/σ-holeBr(-) > π-/σ-holeCl(-) occurs for weak π-hole bonds and σ-hole bonds, whereas the order of electrostatic attraction of π-/σ-holeCl(-) > π-/σ-holeBr(-) > π-/σ-holeI(-) is valid for strong bonds. It can be concluded by combining energy decomposition analysis and natural bond orbital analysis that the π-holeX(-) bond and σ-holeX(-) bond are electrostatically attractive in nature regardless of whether the order is I(-) > Br(-) > Cl(-) or the reverse.

Direct detection of the mercury-nitrogen bond in the thymine-Hg-II-thymine base-pair with Hg-199 NMR spectroscopy

Czech Academy of Sciences Publication Activity Database

Dairaku, T.; Furuita, K.; Sato, H.; Šebera, Jakub; Yamanaka, D.; Otaki, H.; Kikkawa, S.; Kondo, Y.; Katahira, R.; Bickelhaupt, F. M.; Guerra, C. F.; Ono, A.; Sychrovský, Vladimír; Kojima, C.; Tanaka, Y.

2015-01-01

Roč. 51, č. 40 (2015), s. 8488-8491 ISSN 1359-7345 R&D Projects: GA ČR GAP205/10/0228 Institutional support: RVO:61388963 Keywords : T-Hg-T * NMR * spin-spin coupling * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.567, year: 2015 http://pubs.rsc.org/en/content/articlepdf/2015/cc/c5cc02423d

196Hg and 202Hg isotopic ratios in chondrites: revisited

International Nuclear Information System (INIS)

Jovanovic, S.; Reed, G.W. Jr.

1976-01-01

Additional evidence for an isotopically anomalous Hg fraction in unequilibrated meteorites has been obtained using neutron activation to produce 196 Hg and 202 Hg followed by stepwise heating to extract the Hg. In the latest experiments Allende matrix samples released the anomalous Hg but various high-temperature inclusions did not. Nucleogenetic processes are suggested as the probable cause of the anomaly. (Auth.)

Laser-assisted fibrinogen bonding of umbilical vein grafts.

Science.gov (United States)

Oz, M C; Williams, M R; Souza, J E; Dardik, H; Treat, M R; Bass, L S; Nowygrod, R

1993-06-01

Despite success with autologous tissue welding, laser welding of synthetic vascular prostheses has not been possible. The graft material appears inert and fails to allow the collagen breakdown and electrostatic bonding that results in tissue welding. To develop a laser welding system for graft material, we repaired glutaraldehyde-tanned human umbilical cord vein graft incisions using laser-assisted fibrinogen bonding (LAFB) technology. Modified umbilical vein graft was incised transversely (1.2 cm). Incisions were repaired using sutures, laser energy alone, or LAFB. For LAFB, indocyanine green dye was mixed with human fibrinogen and the compound applied with forceps onto the weld site prior to exposure to 808 nm diode laser energy (power density 4.8 W/cm 2). Bursting pressures for sutured repairs (126.6 +/- 23.4 mm Hg) were similar to LAFB anastomoses (111.6 +/- 55.0 mm Hg). No evidence of collateral thermal injury to the graft material was noted. In vivo evaluation of umbilical graft bonding with canine arteries demonstrates that LAFB can reliably reinforce sutured anastomoses. The described system for bonding graft material with laser exposed fibrinogen may allow creation or reinforcement of vascular anastomoses in procedures where use of autologous tissue is not feasible.

Nucleophilicities of Lewis Bases B and Electrophilicities of Lewis Acids A Determined from the Dissociation Energies of Complexes B⋯A Involving Hydrogen Bonds, Tetrel Bonds, Pnictogen Bonds, Chalcogen Bonds and Halogen Bonds.

Science.gov (United States)

Alkorta, Ibon; Legon, Anthony C

2017-10-23

It is shown that the dissociation energy D e for the process B⋯A = B + A for 250 complexes B⋯A composed of 11 Lewis bases B (N₂, CO, HC≡CH, CH₂=CH₂, C₃H₆, PH₃, H₂S, HCN, H₂O, H₂CO and NH₃) and 23 Lewis acids (HF, HCl, HBr, HC≡CH, HCN, H₂O, F₂, Cl₂, Br₂, ClF, BrCl, H₃SiF, H₃GeF, F₂CO, CO₂, N₂O, NO₂F, PH₂F, AsH₂F, SO₂, SeO₂, SF₂, and SeF₂) can be represented to good approximation by means of the equation D e = c ' N B E A , in which N B is a numerical nucleophilicity assigned to B, E A is a numerical electrophilicity assigned to A, and c ' is a constant, conveniently chosen to have the value 1.00 kJ mol -1 here. The 250 complexes were chosen to cover a wide range of non-covalent interaction types, namely: (1) the hydrogen bond; (2) the halogen bond; (3) the tetrel bond; (4) the pnictogen bond; and (5) the chalcogen bond. Since there is no evidence that one group of non-covalent interaction was fitted any better than the others, it appears the equation is equally valid for all the interactions considered and that the values of N B and E A so determined define properties of the individual molecules. The values of N B and E A can be used to predict the dissociation energies of a wide range of binary complexes B⋯A with reasonable accuracy.

A thermodynamic stability of bulk and epitaxial CdHgTe, ZnHgTe and MnHgTe solid solutions

International Nuclear Information System (INIS)

Dejbuk, V.G.; Dremlyuzhenko, S.G.; Ostapov, S.Eh.

2005-01-01

A thermodynamics of Cd 1-x Hg x Te, Zn x Hg 1-x Te and Mg x Hg 1-x Te alloys has been investigated for a delta-lattice parameter model. The phase diagrams obtained show the stability of Cd 1-x Hg x Te, Zn x Hg 1-x Te in the whole range of compositions, alongside with a miscibility gap for Mn x Hg 1-x Te being of 0.35 x Hg 1-x Te/CdTe and Mn x Hg 1-x Te/Cd 0.96 Zn 0.04 Te epitaxial films result in lowering critical temperatures and narrowing the miscibility gap [ru

The Effect of CaCl2 as The Cross Linked Agent on Physic and Chemistry Properties of Whey Protein Edible Film

Directory of Open Access Journals (Sweden)

Manik Eirry Sawitri

2012-02-01

Full Text Available The  aim of this research was to know effect percentage CaCl2 addition as the cross linked agent on physic and chemistry properties of whey protein edible film. The design of this research was completely randomized design, consisted of four treatments: C1 (CaCl2 0.15%, C2 (CaCl2 0.20%, C3 (CaCl2 0.25% and C4 (CaCl2 0.30% which each treatment had three repetitions. The variables were water vapor permeability (wvp, protein solubility, microstructure and electroforetic. The result showed that there was highly significant effect (P<0.01 of the addition CaCl2 on the wvp and protein solubility. C2 treatment gave lower wvp value and protein solubility. CaCl2 addition gave structure of edible film look like porous and not flat on its surface. The electroresis look occured at band more thin with molecular weight 14-18 kDa.   Keywords: edible film whey prtein, CaCl2

Crystal structure of bis(4-acetylanilinium tetrachloridomercurate(II

Directory of Open Access Journals (Sweden)

Manickam Thairiyaraja

2015-12-01

Full Text Available The structure of the title salt, (C8H10NO2[HgCl4], is isotypic with that of the cuprate(II and cobaltate(II analogues. The asymmetric unit contains one 4-acetylanilinium cation and one half of a tetrachloridomercurate(II anion (point group symmetry m. The Hg—Cl distances are in the range 2.4308 (7–2.5244 (11 Å and the Cl—Hg—Cl angles in the range of 104.66 (2–122.94 (4°, indicating a considerable distortion of the tetrahedral anion. In the crystal, cations are linked by an intermolecular N—H...O hydrogen-bonding interaction, leading to a C(8 chain motif with the chains extending parallel to the b axis. There is also a π–π stacking interaction with a centroid-to-centroid distance of 3.735 (2 Å between neighbouring benzene rings along this direction. The anions lie between the chains and interact with the cations through intermolecular N—H...Cl hydrogen bonds, leading to the formation of a three-dimensional network structure.

Intermediate-range chemical ordering of cations in molten RbCl-AgCl

Energy Technology Data Exchange (ETDEWEB)

Tahara, S. [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, Okinawa 903-0213 (Japan); Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), Hyogo 679-5198 (Japan); Kawakita, Y. [J-PARC Center, Japan Atomic Energy Agency (JAEA), Ibaraki 319-1195 (Japan); Shimakura, H. [Faculty of Pharmacy, Niigata University of Pharmacy and Applied Life Sciences, Niigata 956-8603 (Japan); Ohara, K. [Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), Hyogo 679-5198 (Japan); Fukami, T. [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, Okinawa 903-0213 (Japan); Takeda, S. [Department of Physics, Faculty of Sciences, Kyushu University, Fukuoka 812-8581 (Japan)

2015-07-28

A first sharp diffraction peak (FSDP) is observed in the X-ray total structure factor of a molten mixture of RbCl-AgCl, while both pure melts of RbCl and AgCl do not exhibit FSDP individually. Molecular dynamics simulations were performed to investigate the origin of the FSDP with the polarizable ion model (PIM). Coexistence of covalent Ag–Cl and ionic Rb–Cl bonds leads the system to evolve intermediate range ordering, which is simulated by introducing the induced polarization in different ways between Ag–Cl with fully polarizable treatment based on Vashishta-Raman potential and Rb–Cl with suppression over-polarization in the nearest neighbor contribution based on Born-Meyer potential. The partial structure factors for both the Ag–Ag and Rb–Rb correlations, S{sub AgAg}(Q) and S{sub RbRb}(Q), show a positive contribution to the FSDP, while S{sub AgRb}(Q) for the Ag–Rb correlation exhibits a negative contribution, indicating that Ag and Rb ions are distributed in an alternating manner within the intermediate-range length scale. The origin of the intermediate-range chemical ordering of cations can be ascribed to the preferred direction of the dipole moments of anions in the PIM.

Intermediate-range chemical ordering of cations in molten RbCl-AgCl

International Nuclear Information System (INIS)

Tahara, S.; Kawakita, Y.; Shimakura, H.; Ohara, K.; Fukami, T.; Takeda, S.

2015-01-01

A first sharp diffraction peak (FSDP) is observed in the X-ray total structure factor of a molten mixture of RbCl-AgCl, while both pure melts of RbCl and AgCl do not exhibit FSDP individually. Molecular dynamics simulations were performed to investigate the origin of the FSDP with the polarizable ion model (PIM). Coexistence of covalent Ag–Cl and ionic Rb–Cl bonds leads the system to evolve intermediate range ordering, which is simulated by introducing the induced polarization in different ways between Ag–Cl with fully polarizable treatment based on Vashishta-Raman potential and Rb–Cl with suppression over-polarization in the nearest neighbor contribution based on Born-Meyer potential. The partial structure factors for both the Ag–Ag and Rb–Rb correlations, S AgAg (Q) and S RbRb (Q), show a positive contribution to the FSDP, while S AgRb (Q) for the Ag–Rb correlation exhibits a negative contribution, indicating that Ag and Rb ions are distributed in an alternating manner within the intermediate-range length scale. The origin of the intermediate-range chemical ordering of cations can be ascribed to the preferred direction of the dipole moments of anions in the PIM

NAA for studying detoxification of Cr and Hg by Arthrobacter globiformis 151B

International Nuclear Information System (INIS)

Tsibakhashvili, N.; Mosulishvili, L.; Kirkesali, E.; Murusidze, I.; Frontasyeva, M.V.; Pavlov, S.S.; Zinicovscaia, I.I.

2010-01-01

Instrumental neutron activation analysis was used to study accumulation of Hg(II) and Cr(VI) ions in Arthrobacter globiformis 151B, a gram-positive, Cr(VI)-reducer aerobic bacterium isolated from basalt sample taken from the most polluted region in the Republic of Georgia (Kazreti). Experiments were focused on (1) accumulation of Hg(II) in bacterial cells; (2) accumulation of Cr(VI) in A. globiformis 151B in the presence of Hg(II) and (3) effects of Hg(II) and mixture of Cr(VI)-Hg(II) on the elemental composition of bacteria. It was shown that this bacterial strain possesses uptake mechanisms by which mercury toxicity can be reduced in environment and that accumulation of Cr(VI) in A. globiformis 151B is much higher in the presence of Hg(II) ions. Accumulation of Hg(II), similar to the Cr(VI) accumulation, follows well the Lengmuir-Freundlich model. NAA measurements showed increased content of Fe in bacteria under Hg and Cr action, suggesting that Fe-containing biomolecules play a decisive role in detoxifying of heavy metals by A. globiformis 151B. A concentration of 5000 μg/L of Hg(II) was found to be critical for A. globiformis 151B. At this concentration of Hg(II) the concentrations of both essential (Na, Mg, Al, Cl, K, Mn, Zn) and some non-essential elements (Rb, Sb, Sc, As) changed drastically along with a decrease of the biomass of bacteria by a factor of two. One may assume that under this high exposure to Hg(II) the structure of the bacterial cell wall was destroyed. (author)

Crystal structure of metallo DNA duplex containing consecutive Watson-Crick-like T-Hg(II)-T base pairs.

Science.gov (United States)

Kondo, Jiro; Yamada, Tom; Hirose, Chika; Okamoto, Itaru; Tanaka, Yoshiyuki; Ono, Akira

2014-02-24

The metallo DNA duplex containing mercury-mediated T-T base pairs is an attractive biomacromolecular nanomaterial which can be applied to nanodevices such as ion sensors. Reported herein is the first crystal structure of a B-form DNA duplex containing two consecutive T-Hg(II)-T base pairs. The Hg(II) ion occupies the center between two T residues. The N3-Hg(II) bond distance is 2.0 Å. The relatively short Hg(II)-Hg(II) distance (3.3 Å) observed in consecutive T-Hg(II)-T base pairs suggests that the metallophilic attraction could exist between them and may stabilize the B-form double helix. To support this, the DNA duplex is largely distorted and adopts an unusual nonhelical conformation in the absence of Hg(II). The structure of the metallo DNA duplex itself and the Hg(II)-induced structural switching from the nonhelical form to the B-form provide the basis for structure-based design of metal-conjugated nucleic acid nanomaterials. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism

OpenAIRE

Boughlala, Z.; Guerra, C.F.; Bickelhaupt, F.M.

2016-01-01

Abstract We have analyzed the structure and bonding of gas?phase Cl?X and [HCl?X]+ complexes for X+=?H+, CH3 +, Li+, and Na+, using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl? and HCl for the various cations. The Cl?X bond becomes longer and weaker along X+?=?H+, CH3 +, Li+, and Na+. Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence ...

199Hg Moessbauer measurements on mercury, alloys and Hg-fluorides

International Nuclear Information System (INIS)

Wurtinger, W.; Kankeleit, E.

1979-01-01

The Moessbauer effect on the 158 keV 5/2 - -1/2 - transition in 199 Hg, of the order of 10 ppm, has been studied using the current integration technique. The isomer shift between the Hg(I)- and Hg(II)-fluorides as well as the quadrupole splitting in Hg 2 Pt and Hg 2 F 2 are interpreted in terms of relativistic Hartree-Fock-Slater and Molecular Orbital calculations. The following nuclear parameters could be derived: Δ[r 2 ] = (3.2+-1.1) 10 -3 fm 2 and Q(5/2 - ) = (-0.8+-0.4)b. Evidence for an oblate triaxially deformed 199 Hg nucleus is derived from particle plus rotor calculations. (orig.)

Detection of anion-linked polymerization of the tetrameric hemoglobin from Scapharca inaequivalvis by 35Cl NMR spectroscopy

International Nuclear Information System (INIS)

Chiancone, E.; Univ. 'La Sapienza', Rome; Drakenberg, T.; Forsen, S.

1988-01-01

Ion binding to the hemoglobin components of Scaphara inaequivalvis has been measured directly in quadrupole relaxation experiments of 23 Na and 35 Cl. The dimeric and tetrameric hemoglobins interact weakly with sodium ions, but differ in their interaction with chloride ions. The dimeric hemoglobin binds chloride ions with low affinity, whereas the tetrameric protein has high affinity chloride binding sites. Binding of chloride ions to these high affinity sites brings about an oxygen-linked polymerization which manifests itself in an unusual dependence of the 35 Cl excess linewidth on the concentration of the anion. Polymerization is more pronounced in the deoxygenated than in the oxygenated derivative: in the former, it has been observed previously in sedimentation velocity experiments. The sensitivity of the 35 Cl excess linewidth on polymer formation indicates that the residence time of the transiently bound chloride on the tetrameric hemoglobin is not shorter than the correlation time of the molecule (2 X 10 -8 s -1 ). 17 refs.; 2 figs

Graphene composites containing chemically bonded metal oxides

Indian Academy of Sciences (India)

the oxide layers are chemically bonded to graphene (Zhang ... sists of three glass chambers, one to contain the metal halide. (TiCl4, SiCl4 ... In this step, the metal halide reacts with the oxygen function- ... 1·0 g of FeCl3 were vigorously stirred in 30 ml of ethylene ... Reaction with water vapour results in hydrolysis of the un-.

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.

Effect of substrate temperature on corrosion performance of nitrogen doped amorphous carbon thin films in NaCl solution

Energy Technology Data Exchange (ETDEWEB)

Khun, N.W. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Liu, E., E-mail: MEJLiu@ntu.edu.s [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2009-07-01

Nitrogen doped amorphous carbon (a-C:N) thin films were deposited on p-Si substrates by DC magnetron sputtering at varying substrate temperature from room temperature (RT) to 300 {sup o}C. The bonding structure, surface morphology and adhesion strength of the a-C:N films were investigated by using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch testing. The corrosion behavior of the a-C:N films was evaluated by potentiodynamic polarization test in a 0.6 M NaCl solution. The results indicated that the corrosion resistance of the films depended on the sp{sup 3}-bonded cross-link structure that was significantly affected by the substrate temperature.

Effect of substrate temperature on corrosion performance of nitrogen doped amorphous carbon thin films in NaCl solution

International Nuclear Information System (INIS)

Khun, N.W.; Liu, E.

2009-01-01

Nitrogen doped amorphous carbon (a-C:N) thin films were deposited on p-Si substrates by DC magnetron sputtering at varying substrate temperature from room temperature (RT) to 300 o C. The bonding structure, surface morphology and adhesion strength of the a-C:N films were investigated by using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch testing. The corrosion behavior of the a-C:N films was evaluated by potentiodynamic polarization test in a 0.6 M NaCl solution. The results indicated that the corrosion resistance of the films depended on the sp 3 -bonded cross-link structure that was significantly affected by the substrate temperature.

Trimeric Hydrogen Bond in Geometrically Frustrated Hydroxyl Cobalt Halogenides

International Nuclear Information System (INIS)

Xiao-Dong, Liu; Masato, Hagihala; Xu-Guang, Zheng; Dong-Dong, Meng; Wan-Jun, Tao; Sen-Lin, Zhang; Qi-Xin, Guo

2011-01-01

The mid-infrared absorption spectra of geometrically frustrated hydroxyl cobalt halogenides Co 2 (OH) 3 Cl and Co 2 (OH) 3 Br are measured by FTIR spectrometers, and the stretching vibrational modes of hydroxyl groups are found to be 3549cm −1 and 3524cm −1 respectively. Through finding their true terminal O-H group stretching vibration frequencies, we obtain 107cm −1 and 99cm −1 red shift caused by the corresponding O-H···Cl and O-H···Br hydrogen bonds. Rarely reported trimeric hydrogen bonds (Co 3 ≡O-H) 3 ···Cl/Br are pointed out to demonstrate the relative weakness of this kind of hydrogen bond which may have a critical effect on the lattice symmetry and magnetic structures. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Possible link between Hg and Cd accumulation in the brain of long-finned pilot whales (Globicephala melas)

Energy Technology Data Exchange (ETDEWEB)

Gajdosechova, Zuzana [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Brownlow, Andrew [SAC Wildlife Unit, Inverness (United Kingdom); Cottin, Nicolas T.; Fernandes, Mariana [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Read, Fiona L. [Oceanlab, University of Aberdeen, Main Street, Newburgh AB41 6AA (United Kingdom); Urgast, Dagmar S.; Raab, Andrea; Feldmann, Jörg; Krupp, Eva M. [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom)

2016-03-01

The bioaccumulation of metals was investigated by analysis of liver, kidney, muscle and brain tissue of a pod of 21 long-finned pilot whales (Globicephala melas) of all ages stranded in Scotland, UK. The results are the first to report cadmium (Cd) passage through the blood–brain barrier of pilot whales and provide a comprehensive study of the long-term (up to 35 years) mammalian exposure to the environmental pollutants. Additionally, linear accumulation of mercury (Hg) was observed in all studied tissues, whereas for Cd this was only observed in the liver. Total Hg concentration above the upper neurochemical threshold was found in the sub-adult and adult brains and methylmercury (MeHg) of 2.2 mg/kg was found in the brain of one individual. Inter-elemental analysis showed significant positive correlations of Hg with selenium (Se) and Cd with Se in all studied tissues. Furthermore, differences in the elemental concentrations in the liver and brain tissues were found between juvenile, sub-adult and adult groups. The highest concentrations of manganese, iron, zinc, Se, Hg and MeHg were noted in the livers, whereas Cd predominantly accumulated in the kidneys. High concentrations of Hg and Cd in the tissues of pilot whales presented in this study reflect ever increasing toxic stress on marine mammals. - Highlights: • Trace elements were measured in a pod of 21 pilot whales stranded in Scotland. • Bioaccumulation of mercury and methyl mercury was found in all studied tissues. • Cadmium age related accumulation was observed in the liver and brain tissues. • Cadmium-selenium correlations suggest formation of cadmium-selenium complexes.

Possible link between Hg and Cd accumulation in the brain of long-finned pilot whales (Globicephala melas)

International Nuclear Information System (INIS)

Gajdosechova, Zuzana; Brownlow, Andrew; Cottin, Nicolas T.; Fernandes, Mariana; Read, Fiona L.; Urgast, Dagmar S.; Raab, Andrea; Feldmann, Jörg; Krupp, Eva M.

2016-01-01

The bioaccumulation of metals was investigated by analysis of liver, kidney, muscle and brain tissue of a pod of 21 long-finned pilot whales (Globicephala melas) of all ages stranded in Scotland, UK. The results are the first to report cadmium (Cd) passage through the blood–brain barrier of pilot whales and provide a comprehensive study of the long-term (up to 35 years) mammalian exposure to the environmental pollutants. Additionally, linear accumulation of mercury (Hg) was observed in all studied tissues, whereas for Cd this was only observed in the liver. Total Hg concentration above the upper neurochemical threshold was found in the sub-adult and adult brains and methylmercury (MeHg) of 2.2 mg/kg was found in the brain of one individual. Inter-elemental analysis showed significant positive correlations of Hg with selenium (Se) and Cd with Se in all studied tissues. Furthermore, differences in the elemental concentrations in the liver and brain tissues were found between juvenile, sub-adult and adult groups. The highest concentrations of manganese, iron, zinc, Se, Hg and MeHg were noted in the livers, whereas Cd predominantly accumulated in the kidneys. High concentrations of Hg and Cd in the tissues of pilot whales presented in this study reflect ever increasing toxic stress on marine mammals. - Highlights: • Trace elements were measured in a pod of 21 pilot whales stranded in Scotland. • Bioaccumulation of mercury and methyl mercury was found in all studied tissues. • Cadmium age related accumulation was observed in the liver and brain tissues. • Cadmium-selenium correlations suggest formation of cadmium-selenium complexes.

Arene-mercury complexes stabilized by gallium chloride: relative rates of H/D and arene exchange.

Science.gov (United States)

Branch, Catherine S; Barron, Andrew R

2002-11-27

We have previously proposed that the Hg(arene)(2)(GaCl(4))(2) catalyzed H/D exchange reaction of C(6)D(6) with arenes occurs via an electrophilic aromatic substitution reaction in which the coordinated arene protonates the C(6)D(6). To investigate this mechanism, the kinetics of the Hg(C(6)H(5)Me)(2)(GaCl(4))(2) catalyzed H/D exchange reaction of C(6)D(6) with naphthalene has been studied. Separate second-order rate constants were determined for the 1- and 2-positions on naphthalene; that is, the initial rate of H/D exchange = k(1i)[Hg][C-H(1)] + k(2i)[Hg][C-H(2)]. The ratio of k(1i)/k(2i) ranges from 11 to 2.5 over the temperature range studied, commensurate with the proposed electrophilic aromatic substitution reaction. Observation of the reactions over an extended time period shows that the rates change with time, until they again reach a new and constant second-order kinetics regime. The overall form of the rate equation is unchanged: final rate = k(1f)[Hg][C-H(1)] + k(2f)[Hg][C-H(2)]. This change in the H/D exchange is accompanied by ligand exchange between Hg(C(6)D(6))(2)(GaCl(4))(2) and naphthalene to give Hg(C(10)H(8))(2)(GaCl(4))(2,) that has been characterized by (13)C CPMAS NMR and UV-visible spectroscopy. The activation parameters for the ligand exchange may be determined and are indicative of a dissociative reaction and are consistent with our previously calculated bond dissociation for Hg(C(6)H(6))(2)(AlCl(4))(2). The initial Hg(arene)(2)(GaCl(4))(2) catalyzed reaction of naphthalene with C(6)D(6) involves the deuteration of naphthalene by coordinated C(6)D(6); however, as ligand exchange progresses, the pathway for H/D exchange changes to where the protonation of C(6)D(6) by coordinated naphthalene dominates. The site selectivity for the H/D exchange is initially due to the electrophilic aromatic substitution of naphthalene. As ligand exchange occurs, this selectivity is controlled by the activation of the naphthalene C-H bonds by mercury.

Dissociation of deep-core-excited CH{sub 3}Cl

Energy Technology Data Exchange (ETDEWEB)

Hansen, D.L.; Martin, R.; Vanderford, B. [Univ. of Nevada, Las Vegas, NV (United States)] [and others

1997-04-01

Using x-rays from B.L. 9.3.1, a space-focused time-of-flight (TOF) was used to study photofragmentation of CH{sub 3}Cl following excitation in the neighborhood of the Cl K-shell threshold ({approximately} 2.8 keV). Multi-ion coincidence measurements were used to search for selective dissociation of specific bonds in the molecule. Such selectivity has been observed for excitation near outer-core-level thresholds (e.g., Cl 2p), but this is the first study in deep core levels, where very-short core-hole lifetimes and Auger cascade effects may influence fragmentation. Both high-resolution time-of-flight spectroscopy and multi-coincidence photoelectron-photoion-photoion (PE-PIPICO), as well as photoelectron-photoion-photoion-photoion (PE3PICO) measurements were performed. Dramatic changes in the line shapes for different fragment ions are observed as a function of the excitation energy, and are attributed to selective dissociation of the CH{sub 3}Cl molecule along the C-Cl bond. In addition, pronounced angular distributions of the ejected ions are observed on resonance.

Structure of the mercury(II mixed-halide (Br/Cl complex of 2,2′-(5-tert-butyl-1,3-phenylenebis(1-pentyl-1H-benzo[d]imidazole

Directory of Open Access Journals (Sweden)

Varsha Rani

2017-03-01

Full Text Available The mercury(II complex of 2,2′-(5-tert-butyl-1,3-phenylenebis(1-pentyl-1H-benzimidazole, namely catena-poly[[dihalogenidomercury(II]-μ-2,2′-(5-tert-butyl-1,3-phenylenebis(1-pentyl-1H-benzimidazole-κ2N3:N3′], [HgBr1.52Cl0.48(C34H42N4], 2, has a polymeric structure bridging via the N atoms from the benzimidazole moieties of the ligand. The compound crystallizes in the orthorhombic space group Pca21 and is a racemic twin [BASF = 0.402 (9]. The geometry around the HgII atom is distorted tetrahedral, with the HgII atom coordinated to two N atoms, one Br atom, and a fourth coordination site is occupied by a mixed halide (Br/Cl. For the two ligands in the asymmetric unit, there is disorder with one of the two tert-butyl groups and benzimidazole moieties showing twofold disorder, with occupancy factors of 0.57 (2:0.43 (2 for the tert-butyl group and 0.73 (3:0.27 (3 for the benzimidazole group. In addition, there is threefold disorder for two of the four n-pentyl groups, with occupancy factors of 0.669 (4:0.177 (4:0.154 (4 and 0.662 (4:0.224 (4:0.154 (4, respectively. The molecules form a one-dimensional helical polymer propagating in the b-axis direction. The helices are held together by intra-strand C—H...Br and C—H...Cl interactions. Each strand is further linked by inter-strand C—H...Br and C—H...Cl interactions. In addition, there are weak C—H...N inter-strand interactions which further stabilize the structural arrangement.

Recovery of total Hg from geological matrices: a methodological intercomparison study (W6)

International Nuclear Information System (INIS)

Bloom, N.S.; Vondergeest, E.J.; Preus, E.M.; Horvat, M.; Prosenc, N.; Kingston, S.; Apte, S.; Pobbs, C.

2002-01-01

Full text: Aqua regia is commonly used for the extraction of Hg from soils prior to cold vapor spectrometry, but mass balance studies suggested it is not sufficiently robust to recover all Hg from more recalcitrant materials such as crystalline ores. As a result, an intercomparison exercise was undertaken between the following methods: (a) aqua regia digestion (EPA 7471) followed by SnCl 2 reduction, gold trapping and CVAFS detection, (b) Teflon bomb digestion at 110 o C with a 10:5:2 HNO 3 + HF + HCl mixture followed by SnCl 2 reduction, gold trapping and CVAFS, (c) 800 o C pyrolysis with gold trapping and CVAAS detection (EPA 7473), and (d) NAA followed by radiochemical separations using oxidative combustion and gold trapping. All methods gave quantitative recoveries from soil and sediment CRMs, but only the HF/HCI/HNO 3 digestion gave quantitative recoveries in all media. Pyrolysis resulted in approximately 88 ± 10 % recovery, while aqua regia digestion resulted in only about 61 ± 24 % recovery in bauxite ores and residues. RNAA generally gave the best agreement with the HF based digestion, although in a significant number of samples, particularly bauxite ores, recoveries were as low as 50 %. Based on these findings, we recommend that bomb digestions which include the use HF be applied to the analysis of Hg in geological solids, unless the matrix is documented to be fully extractable by a less rigorous procedure. We suggest a reference value for Hg in bauxite reference material (NIST-600) of 79.0 ± 2.0 ng/g, based on the pooled results of three laboratories. (author)

Studies of the 198Hg(d,d') and 198Hg(d,p) reactions

Science.gov (United States)

Diaz Varela, Alejandra; Garrett, P. E.; Rand, E. T.; Ball, G. C.; Bilstein, V.; Laffoley, A. T.; Maclean, A. D.; Svensson, C. E.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.

2017-09-01

Limits on the electric dipole moment (EDM) continue to decrease for 199Hg, the most stringent upper limit for a nuclear EDM to date. The experimental limit on the observed atomic EDM for 199Hg is converted to a limit on the nuclear EDM via a calculation of the Schiff moment, requiring knowledge of the nuclear structure of 199Hg. The E 3 and E 1 strength distributions to the ground state of 199Hg, and E 2 transitions amongst excited states, would be ideal information to further constrain 199Hg Schiff moment theoretical models. The high level density of 199Hg makes those determinations challenging, however the similar information can be obtained from exploring surrounding even-even Hg isotopes. As part of a campaign to study the Hg isotopes near 199Hg, two experiments, 198Hg(d,d') 198Hg and 198Hg(d,p)199Hg reaction were performed using the Q3D spectrograph at the Maier-Leibnitz Laboratory (MLL) at Garching, Germany. A 22 MeV deuterium beam was used to impinge a 198Hg32S target. The (d,d') reaction allows us to probe the desired E 2 and E 3 matrix elements, while the (d,p) reaction provides information on the neutron single-particle states of 199Hg.

Origin of the X-Hal (Hal ) Cl, Br) Bond-Length Change in the Halogen-Bonded Complexes

Czech Academy of Sciences Publication Activity Database

Wang, Weizhou; Hobza, Pavel

2008-01-01

Roč. 112, č. 17 (2008), s. 4114-4119 ISSN 1089-5639 R&D Projects: GA MŠk LC512; GA AV ČR IAA400550510 Institutional research plan: CEZ:AV0Z40550506 Keywords : hal ogen bonded complexes * MP2(full)/6-311++G(d,p) method * natural bond orbital analysis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.871, year: 2008

Innate stimulatory capacity of high molecular weight transition metals Au (gold) and Hg (mercury).

Science.gov (United States)

Rachmawati, Dessy; Alsalem, Inás W A; Bontkes, Hetty J; Verstege, Marleen I; Gibbs, Sue; von Blomberg, B M E; Scheper, Rik J; van Hoogstraten, Ingrid M W

2015-03-01

Nickel, cobalt and palladium ions can induce an innate immune response by triggering Toll-like receptor (TLR)-4 which is present on dendritic cells (DC). Here we studied mechanisms of action for DC immunotoxicity to gold and mercury. Next to gold (Na3Au (S2O3)2⋅2H2O) and mercury (HgCl2), nickel (NiCl2) was included as a positive control. MoDC activation was assessed by release of the pro-inflammatory mediator IL-8. Also PBMC were studied, and THP-1 cells were used as a substitution for DC for evaluation of cytokines and chemokines, as well as phenotypic, alterations in response to gold and mercury. Our results showed that both Na3Au (S2O3)2⋅2H2O and HgCl2 induce substantial release of IL-8, but not IL-6, CCL2 or IL-10, from MoDc, PBMC, or THP-1 cells. Also gold and, to a lesser extent mercury, caused modest dendritic cell maturation as detected by increased membrane expression of CD40 and CD80. Both metals thus show innate immune response capacities, although to a lower extent than reported earlier for NiCl2, CoCl2 and Na2 [PdCl4]. Importantly, the gold-induced response could be ascribed to TLR3 rather than TLR4 triggering, whereas the nature of the innate mercury response remains to be clarified. In conclusion both gold and mercury can induce innate immune responses, which for gold could be ascribed to TLR3 dependent signalling. These responses are likely to contribute to adaptive immune responses to these metals, as reflected by skin and mucosal allergies. Copyright © 2014 Elsevier Ltd. All rights reserved.

46 CFR 53.12-1 - General (modifies HG-600 through HG-640).

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false General (modifies HG-600 through HG-640). 53.12-1... HEATING BOILERS Instruments, Fittings, and Controls (Article 6) § 53.12-1 General (modifies HG-600 through HG-640). (a) The instruments, fittings and controls for heating boilers shall be as indicated in HG...

Structure of Chloro bis(1,10-phenanthroline)Cobalt(II) Complex, [Co(phen)2(Cl)(H2O)]Cl · 2H2O

International Nuclear Information System (INIS)

Zhao, Pu Su; Lu, Lu De; Jian, Fang Fang

2003-01-01

The crystal structure of [Co(phen) 2 (Cl)(H 2 O)] Cl · 2H 2 O(phen=1,10-phenanthroline) has been determined by X-ray crystallography. It crystallizes in the triclinic system, space group P 1 , with lattice parameters a=9.662(2), b=11.445(1), c=13.037(2)A, α=64.02(1), β=86.364(9), γ=78.58(2) .deg., and Z=2. The coordinated cations contain a six-coordinated cobalt atom chelated by two phen ligands and one chloride anion and one water ligand in cis arrangement. In addition to the chloride coordinated to the cobalt, there are one chloride ion and four water molecules which complete the crystal structure. In the solid state, the title compound forms three dimensional network structure through hydrogen bonds, within which exists the strongest hydrogen bond (O(3)-O(4)=2.33A). The intermolecular hydrogen bonds connect the [Co(phen) 2 (Cl)(H 2 O)] 1+ , H 2 O moieties and chloride ion

Quadrupole moments of the 12+ isomers in 188Hg and 190Hg

International Nuclear Information System (INIS)

Dracoulis, G.D.; Lonnroth, T.; Vajda, S.; Dafni, E.; Schatz, G.

1984-01-01

The electric quadrupole interaction of the 12 + isomers in 188 Hg and 190 Hg has been measured in solid Hg. The quadrupole moments deduced, vertical strokeQ[ 188 Hg(12 + )]vertical stroke = 91(11) e fm 2 and vertical strokeQ[ 190 Hg(12 + )]vertical stroke = 117(14) e fm 2 suggest a possible change in γ-deformation due to the rotation alignment of the isub(13/2) quasi-neutrons. The temperature dependence of the electric field gradient tensor in Hg was also determined. (orig.)

Tracing aquatic bioavailable Hg in three different regions of China using fish Hg isotopes.

Science.gov (United States)

Liu, Cheng-Bin; Hua, Xiu-Bing; Liu, Hong-Wei; Yu, Ben; Mao, Yu-Xiang; Wang, Ding-Yong; Yin, Yong-Guang; Hu, Li-Gang; Shi, Jian-Bo; Jiang, Gui-Bin

2018-04-15

To trace the most concerned bioavailable mercury (Hg) in aquatic environment, fish samples were collected from three typical regions in China, including 3 rivers and 1 lake in the Tibetan Plateau (TP, a high altitude background region with strong solar radiation), the Three Gorges Reservoir (TGR, the largest artificial freshwater reservoir in China), and the Chinese Bohai Sea (CBS, a heavily human-impacted semi-enclosed sea). The Hg isotopic compositions in fish muscles were analyzed. The results showed that anthropogenic emissions were the main sources of Hg in fish from TGR and CBS because of the observed negative δ 202 Hg and positive Δ 199 Hg in these two regions (TGR, δ 202 Hg: - 0.72 to - 0.29‰, Δ 199 Hg: 0.15 - 0.52‰; CBS, δ 202 Hg: - 2.09 to - 0.86‰, Δ 199 Hg: 0.07 - 0.52‰). The relatively higher δ 202 Hg and Δ 199 Hg (δ 202 Hg: - 0.37 - 0.08‰, Δ 199 Hg: 0.50 - 1.89‰) in fish from TP suggested the insignificant disturbance from local anthropogenic activities. The larger slopes of Δ 199 Hg/Δ 201 Hg in fish from TGR (1.29 ± 0.14, 1SD) and TP (1.25 ± 0.06, 1SD) indicated methylmercury (MeHg) was produced and photo-reduced in the water column before incorporation into the fish. In contrast, the photoreduction of Hg 2+ was the main process in CBS (slope of Δ 199 Hg/Δ 201 Hg: 1.06 ± 0.06, 1SD). According to the fingerprint data of Hg isotopes, the most important source for aquatic bioavailable Hg in TP should be the long-range transported Hg, contrasting to the anthropogenic originated MeHg from surface sediments and runoffs in TGR and inorganic Hg from continental inputs in CBS. Therefore, the isotopic signatures of Hg in fish can provide novel clues in tracing sources and behaviors of bioavailable Hg in aquatic systems, which are critical for further understanding the biogeochemical cycling of Hg. Copyright © 2017 Elsevier Inc. All rights reserved.

Comparative study of fixation of Co57 labelled bleomycin, labelled gallium citrate and Hg197 labelled mercury chloride, benign or malignant pulmonary lesions

International Nuclear Information System (INIS)

Bertrand, A.; Vaillant, G.; Robert, J.; Vaillant, D.; Nouel, J.P.; Delorme, J.; Lamy, P.

1975-01-01

Over the last ten years, numerous labelled molecules have been used in lung diseases, in order to attempt definite localisation of primary or secondary carcinoma. Three of these substances are now used: cobalt 57-labelled bleomycin, Hg 197 Cl 2 and Ga 67 citrate. A study of 34 patient with malignant or tuberculous lung disease with definite diagnosis, permitted demonstration of the fact that the highest uptake, or the best images, were obtained with labelled bleomycin. However, the long period of Co 57 limits its indications in young subjects and, in these cases, HgCl 2 is indicated [fr

Photochemical reactions between mercury (Hg) and dissolved organic matter decrease Hg bioavailability and methylation.

Science.gov (United States)

Luo, Hong-Wei; Yin, Xiangping; Jubb, Aaron M; Chen, Hongmei; Lu, Xia; Zhang, Weihua; Lin, Hui; Yu, Han-Qing; Liang, Liyuan; Sheng, Guo-Ping; Gu, Baohua

2017-01-01

Atmospheric deposition of mercury (Hg) to surface water is one of the dominant sources of Hg in aquatic environments and ultimately drives methylmercury (MeHg) toxin accumulation in fish. It is known that freshly deposited Hg is more readily methylated by microorganisms than aged or preexisting Hg; however the underlying mechanism of this process is unclear. We report that Hg bioavailability is decreased by photochemical reactions between Hg and dissolved organic matter (DOM) in water. Photo-irradiation of Hg-DOM complexes results in loss of Sn(II)-reducible (i.e. reactive) Hg and up to an 80% decrease in MeHg production by the methylating bacterium Geobacter sulfurreducens PCA. Loss of reactive Hg proceeded at a faster rate with a decrease in the Hg to DOM ratio and is attributed to the possible formation of mercury sulfide (HgS). These results suggest a new pathway of abiotic photochemical formation of HgS in surface water and provide a mechanism whereby freshly deposited Hg is readily methylated but, over time, progressively becomes less available for microbial uptake and methylation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Equilibrium mercury isotope fractionation between dissolved Hg(II) species and thiol-bound Hg

NARCIS (Netherlands)

Wiederhold, Jan G.; Cramer, Christopher J.; Daniel, Kelly; Infante, Ivan; Bourdon, Bernard; Kretzschmar, Ruben

2010-01-01

Stable Hg isotope ratios provide a new tool to trace environmental Hg cycling. Thiols (-SH) are the dominant Hg-binding groups in natural organic matter. Here, we report experimental and computational results on equilibrium Hg isotope fractionation between dissolved Hg(II) species and thiol-bound

46 CFR 53.10-3 - Inspection and tests (modifies HG-500 through HG-540).

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Inspection and tests (modifies HG-500 through HG-540... tests (modifies HG-500 through HG-540). (a) The inspections required by HG-500 through HG-540 must be performed by the “Authorized Inspector” as defined in HG-515 of section IV of the ASME Boiler and Pressure...

Synthesis and crystal structure of Fe[(Te1.5Se0.5)O5]Cl, the first iron compound with selenate(IV) and tellurate(IV) groups

Science.gov (United States)

Akhrorov, Akhmad Yu; Kuznetsova, Elena S.; Aksenov, Sergey M.; Berdonosov, Peter S.; Kuznetsov, Alexey N.; Dolgikh, Valery A.

2017-12-01

During the search for selenium analogues of FeTe2O5Cl, the new iron (III) tellurate(IV) selenate(IV) chloride with the composition Fe[(Te1.5Se0.5)O5]Cl was synthesized by chemical vapor transport (CVT) reaction and characterized by TGA-, EDX-,SCXRD-analysis, as well as IR and Raman spectroscopy. It was found that Fe[(Te1.5Se0.5)O5]Cl crystallizes in the monoclinic space group P21/c with unitcell parameters a = 5.183(3) Å, b = 15.521(9) Å, c = 7.128(5) Å and β = 107.16(1)°. The crystal structure of Fe[(Te1.5Se0.5)O5]Cl represents a new structure type and contains electroneutral heteropolyhedral layers formed by dimers of the [FeO5Cl]8- octahedra, linked via common O-O edges, and mixed [Te3SeO10]4- tetramers. Adjacent layers are stacked along the b axis and linked by weak residual bonds. The new compound is stable up to 420 °C. DFT calculations predict Fe[(Te1.5Se0.5)O5]Cl to be a wide-gap semiconductor with the band gap of ca. 2.7 eV.

Zn2+, Cd2+, Hg2+ thiolates - derivatives of 2, 3, 5-trifluoro-4,6-bis(trifluoromethyl)thiophenol and heptafluoro-2-thionaphthol

International Nuclear Information System (INIS)

Larionov, S.V.; Kirichenko, V.N.; Platonov, V.E.; Maksimov, A.M.; Rodionov, P.P.; Fadeeva, V.P.; Oglezneva, I.M.; Lisojvan, V.I.; AN SSSR, Novosibirsk

1992-01-01

Zn 2+ , Cd 2+ , Hg 2+ coordination compounds with 2, 3, 5 -trifluoro- 4,6 bis(trifluoromethyl)trhiophenol (MHal) and heptafluoro-2-thionophthal (HT) of ZnHal 2 (CH 3 OH), CdHal 2 , HgHal 2 and MT 2 (M=Zn, Cd, Hg) composition, are obtained. Complexes are studied using thermal and X-ray phase analysis, vapour phase osmometry and IR spectroscopy, ZnHal 2 (CH 3 OH), CdHal 2 , ZnT 2 , HgHfl 2 , HgT 2 compounds in acetone solutions are in monomeric state, while in CdT 2 commeric particles. Frequencies of mostly valent vibrations of Cd-S bond are observed at 241 (CdHal 2 ), 225 (CdT 2 )

Manila clams from Hg polluted sediments of Marano and Grado lagoons (Italy) harbor detoxifying Hg resistant bacteria in soft tissues

International Nuclear Information System (INIS)

Baldi, Franco; Gallo, Michele; Marchetto, Davide; Faleri, Claudia; Maida, Isabel; Fani, Renato

2013-01-01

A mechanism of mercury detoxification has been suggested by a previous study on Hg bioaccumulation in Manila clams (Ruditapes philippinarum) in the polluted Marano and Grado lagoons and in this study we demonstrate that this event could be partly related to the detoxifying activities of Hg-resistant bacteria (MRB) harbored in clam soft tissues. Therefore, natural clams were collected in six stations during two different periods (winter and spring) from Marano and Grado Lagoons. Siphons, gills and hepatopancreas from acclimatized clams were sterile dissected to isolate MRB. These anatomical parts were glass homogenized or used for whole, and they were lying on a solid medium containing 5 mg l −1 HgCl 2 and incubated at 30 °C. A total of fourteen bacterial strains were isolated and were identified by 16S rDNA sequencing and analysis, revealing that strains were representative of eight bacterial genera, four of which were Gram-positive (Enterococcus, Bacillus, Jeotgalicoccus and Staphylococcus) and other four were Gram-negative (Stenotrophomonas, Vibrio, Raoultella and Enterobacter). Plasmids and merA genes were found and their sequences determined. Fluorescence in situ hybridization (FISH) technique shows the presence of Firmicutes, Actinobacteria and Gammaproteobacteria by using different molecular probes in siphon and gills. Bacterial clumps inside clam flesh were observed and even a Gram-negative endosymbiont was disclosed by transmission electronic microscope inside clam cells. Bacteria harbored in cavities of soft tissue have mercury detoxifying activity. This feature was confirmed by the determination of mercuric reductase in glass-homogenized siphons and gills. -- Highlights: ► We isolated Gram-positive and Gram-negative Hg resistant strains from soft tissues of Ruditapes philippinarum. ► We identify 14 mercury resistant strains by 16S rRNA gene sequences. ► Bacteria in siphon and gill tissues of clams were observed by TEM and identified with

Manila clams from Hg polluted sediments of Marano and Grado lagoons (Italy) harbor detoxifying Hg resistant bacteria in soft tissues

Energy Technology Data Exchange (ETDEWEB)

Baldi, Franco [Dipartimento di Scienze Molecolari e Nanosistemi, Cà Foscari University of Venice, Dorsoduro 2137, 30123 Venice (Italy); Gallo, Michele; Marchetto, Davide [Dipartimento di Scienze Molecolari e Nanosistemi, Cà Foscari University of Venice, Dorsoduro 2137, 30123 Venice (Italy); Faleri, Claudia [Department of Environmental Science ‘G. Sarfatti’, University of Siena, 53100 Siena (Italy); Maida, Isabel; Fani, Renato [Dipartimento di Biologia Evoluzionistica, Via Romana, 17, University of Florence, 50125 Florence (Italy)

2013-08-15

A mechanism of mercury detoxification has been suggested by a previous study on Hg bioaccumulation in Manila clams (Ruditapes philippinarum) in the polluted Marano and Grado lagoons and in this study we demonstrate that this event could be partly related to the detoxifying activities of Hg-resistant bacteria (MRB) harbored in clam soft tissues. Therefore, natural clams were collected in six stations during two different periods (winter and spring) from Marano and Grado Lagoons. Siphons, gills and hepatopancreas from acclimatized clams were sterile dissected to isolate MRB. These anatomical parts were glass homogenized or used for whole, and they were lying on a solid medium containing 5 mg l{sup −1} HgCl{sub 2} and incubated at 30 °C. A total of fourteen bacterial strains were isolated and were identified by 16S rDNA sequencing and analysis, revealing that strains were representative of eight bacterial genera, four of which were Gram-positive (Enterococcus, Bacillus, Jeotgalicoccus and Staphylococcus) and other four were Gram-negative (Stenotrophomonas, Vibrio, Raoultella and Enterobacter). Plasmids and merA genes were found and their sequences determined. Fluorescence in situ hybridization (FISH) technique shows the presence of Firmicutes, Actinobacteria and Gammaproteobacteria by using different molecular probes in siphon and gills. Bacterial clumps inside clam flesh were observed and even a Gram-negative endosymbiont was disclosed by transmission electronic microscope inside clam cells. Bacteria harbored in cavities of soft tissue have mercury detoxifying activity. This feature was confirmed by the determination of mercuric reductase in glass-homogenized siphons and gills. -- Highlights: ► We isolated Gram-positive and Gram-negative Hg resistant strains from soft tissues of Ruditapes philippinarum. ► We identify 14 mercury resistant strains by 16S rRNA gene sequences. ► Bacteria in siphon and gill tissues of clams were observed by TEM and identified

Theoretical estimation of pnicogen bonds and hydrogen bonds in small heterocyclic complexes: Red-shifts and blue-shifts ruled by polarization effects

International Nuclear Information System (INIS)

Oliveira, Boaz G.

2014-01-01

Graphical abstract: - Highlights: • This paper definitively discusses the interaction strength. • Analyses of the red-shifts and blue-shift. • Stretch frequencies of the hydrogen bonds and pnicogen bonds in heterocyclic compounds. • Theoretical calculations derived from topological parameters of the Quantum Theory of Atoms in Molecules (QTAIM). • The analysis of the Natural Bond Orbital (NBO) in line with the Bent’s rule of the chemical bonding. - Abstract: The occurrence of pnicogen bonds (N⋯P) and hydrogen bonds (F⋯H or Cl⋯H) in heterocyclic complexes formed by C 2 H 5 N⋯PH 3 , C 2 H 5 N⋯PH 2 F and C 2 H 5 N⋯PH 2 Cl was investigated at the B3LYP/6-311++G(d,p) level of theory. Analysis of the infrared spectra revealed the appearance of both red and blue shifts for the P–H bonds. However, in the case of the P–F and P–Cl bonds only red shifts were observed. The phenomenology of these vibration modes was interpreted on the basis of the QTAIM atomic radii as well as the contributions of the s and p orbitals determined via NBO calculations. The results of this latter investigation are consistent with the rehybridization theory and the Bent rule for chemical bonding. The charge transfer between N and P was determined in order to verify whether these atoms present an acid or base profile upon the formation of the pnicogen bonds

B-H Bond Activation by an Amidinate-Stabilized Amidosilylene: Non-Innocent Amidinate Ligand.

Science.gov (United States)

Khoo, Sabrina; Shan, Yu-Liang; Yang, Ming-Chung; Li, Yongxin; Su, Ming-Der; So, Cheuk-Wai

2018-05-21

The activation of B-H and B-Cl bonds in boranes by base-stabilized low-valent silicon compounds is described. The reaction of the amidinato amidosilylene-borane adduct [L{Ar(Me 3 Si)N}SiBH 3 ] [1; L = PhC(N tBu) 2 , and Ar = 2,6- iPr 2 C 6 H 3 ] with MeOTf in toluene at room temperature formed [L{Ar(Me 3 Si)N}SiBH 2 OTf] (2). [LSiN(SiMe 3 )Ar] in compound 2 then underwent a B-H bond activation with BH 2 OTf in refluxing toluene to afford the B-H bond activation product [LB(H)Si(H)(OTf){N(SiMe 3 )Ar}] (3). On the other hand, when compound 2 was reacted with 4-dimethylaminopyridine in refluxing toluene, another B-H bond activation product [(μ-κ1:κ1-L)B(H)(DMAP)Si(H){N(Ar)SiMe 3 }]OTf (4) was afforded. Mechanistic studies show that "(μ-κ1:κ1-L)B(H)(OTf)Si(H){N(Ar)SiMe 3 }" (2A) is the key intermediate in the reactions mentioned above. The formation of 2A is further evidenced by the activation of the B-Cl bond in PhBCl 2 by the amidinato silicon(I) dimer [LSi:] 2 to form the B-Cl bond activation product [(μ-κ1:κ1-L)B(Cl)(Ph)Si(Cl)] 2 (6). Compounds 2-4 and 6 were characterized by nuclear magnetic resonance spectroscopy and X-ray crystallography.

Mercury Stable Isotopes Discriminate Different Populations of European Seabass and Trace Potential Hg Sources around Europe.

Science.gov (United States)

Cransveld, Alice; Amouroux, David; Tessier, Emmanuel; Koutrakis, Emmanuil; Ozturk, Ayaka A; Bettoso, Nicola; Mieiro, Cláudia L; Bérail, Sylvain; Barre, Julien P G; Sturaro, Nicolas; Schnitzler, Joseph; Das, Krishna

2017-11-07

Our study reports the first data on mercury (Hg) isotope composition in marine European fish, for seven distinct populations of the European seabass, Dicentrarchus labrax. The use of δ 202 Hg and Δ 199 Hg values in SIBER enabled us to estimate Hg isotopic niches, successfully discriminating several populations. Recursive-partitioning analyses demonstrated the relevance of Hg stable isotopes as discriminating tools. Hg isotopic values also provided insight on Hg contamination sources for biota in coastal environment. The overall narrow range of δ 202 Hg around Europe was suggested to be related to a global atmospheric contamination while δ 202 Hg at some sites was linked either to background contamination, or with local contamination sources. Δ 199 Hg was related to Hg levels of fish but we also suggest a relation with ecological conditions. Throughout this study, results from the Black Sea population stood out, displaying a Hg cycling similar to fresh water lakes. Our findings bring out the possibility to use Hg isotopes in order to discriminate distinct populations, to explore the Hg cycle on a large scale (Europe) and to distinguish sites contaminated by global versus local Hg source. The interest of using Hg sable isotopes to investigate the whole European Hg cycle is clearly highlighted.

Effect of Sr substitution on superconductivity in Hg2(Ba1-ySry)2YCu2O8-d (part2): bond valence sum approach of the hole distribution

OpenAIRE

Toulemonde, P.; Odier, P.; Bordet, P.; Floch, S. Le; Suard, E.

2004-01-01

The effects of Sr substitution on superconductivity, and more particulary the changes induced in the hole doping mechanism, were investigated in Hg2(Ba1-ySry)2YCu2O8-d by a "bond valence sum" analysis with Sr content from y = 0.0 to y = 1.0. A comparison with CuBa2YCu2O7-d and Cu2Ba2YCu2O8 systems suggests a possible explanation of the Tc enhancement from 0 K for y = 0.0 to 42 K for y = 1.0. The charge distribution among atoms of the unit cell was determined from the refined structure, for y ...

The Hydrogen Bonded Structures of Two 5-Bromobarbituric Acids and Analysis of Unequal C5–X and C5–X′ Bond Lengths (X = X′ = F, Cl, Br or Me in 5,5-Disubstituted Barbituric Acids

Directory of Open Access Journals (Sweden)

Thomas Gelbrich

2016-04-01

Full Text Available The crystal structure of the methanol hemisolvate of 5,5-dibromobarbituric acid (1MH displays an H-bonded layer structure which is based on N–H∙∙∙O=C, N–H∙∙∙O(MeOH and (MeOHO–H∙∙∙O interactions. The barbiturate molecules form an H-bonded substructure which has the fes topology. 5,5′-Methanediylbis(5-bromobarbituric acid 2, obtained from a solution of 5,5-dibromobarbituric acid in nitromethane, displays a N–H···O=C bonded framework of the sxd type. The conformation of the pyridmidine ring and the lengths of the ring substituent bonds C5–X and C5–X′ in crystal forms of 5,5-dibromobarbituric acid and three closely related analogues (X = X′ = Br, Cl, F, Me have been investigated. In each case, a conformation close to a C5-endo envelope is correlated with a significant lengthening of the axial C5–X′ in comparison to the equatorial C5–X bond. Isolated molecule geometry optimizations at different levels of theory confirm that the C5-endo envelope is the global conformational energy minimum of 5,5-dihalogenbarbituric acids. The relative lengthening of the axial bond is therefore interpreted as an inherent feature of the preferred envelope conformation of the pyrimidine ring, which minimizes repulsive interactions between the axial substituent and pyrimidine ring atoms.

Effect of the value of bond energy on the defect formation in the samples of CdTe - HqTe system under the influence of irradiation

International Nuclear Information System (INIS)

Kramchenko, O.A.; Pashkovskij, N.V.

1984-01-01

The bonds break energy in solid solutions of the CdTe-HgTe system is calculated. The correctness of the statement that bonds strength in a chemical compound, particularly for the CdTe-HgTe system with decreases with the increase of atomic number. It is shown that in the process of transition from CdTe binary compound to solid solutions of the CdTe-HgTe system a part of Cd atoms is substituted by Hg atoms, which causes relative decrease of the number Cd-Te bonds. At the same time increased is the number of Cd-Te bonds which during irradiation break more probably than the Cd-Te bonds forming however only Frenkel close vapours annihilating during irradiation. During the experiment these defects lead to temperature region washout in which properties reconstruction at isochronous annealing begins. The beginning of annealing is shifted towards higher temperatures which has been observed in the course of investigation. X decrease for the Cdsub(x)Hgsub(1-x)Te solid solution increases the annealing temperature of radiation defects The results of theoretical calculations coincide with the experimental data and permit to confirm that the properties changes arising during irradiation of matters with weak chemical bonds can be conserved only at very low temperatures

Long-distance transport of Hg, Sb, and As from a mined area, conversion of Hg to methyl-Hg, and uptake of Hg by fish on the Tiber River basin, west-central Italy

Science.gov (United States)

Gray, John E.; Rimondi, Valentina; Costagliola, Pilario; Vaselli, Orlando; Lattanzi, Pierfranco

2014-01-01

Stream sediment, stream water, and fish were collected from a broad region to evaluate downstream transport and dispersion of mercury (Hg) from inactive mines in the Monte Amiata Hg District (MAMD), Tuscany, Italy. Stream sediment samples ranged in Hg concentration from 20 to 1,900 ng/g, and only 5 of the 17 collected samples exceeded the probable effect concentration for Hg of 1,060 ng/g, above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in Tiber River sediment varied from 0.12 to 0.52 ng/g, and although there is no established guideline for sediment methyl-Hg, these concentrations exceeded methyl-Hg in a regional baseline site (water varied from 1.2 to 320 ng/L, all of which were below the 1,000 ng/L Italian drinking water Hg guideline and the 770 ng/L U.S. Environmental Protection Agency (USEPA) guideline recommended to protect against chronic effects to aquatic wildlife. Methyl-Hg concentrations in stream water varied from water samples contained concentrations of As (drinking water guidelines to protect human health (10 μg/L for As and 20 μg/L for Sb) and for protection against chronic effects to aquatic wildlife (150 μg/L for As and 5.6 μg/L for Sb). Concentrations of Hg in freshwater fish muscle ranged from 0.052–0.56 μg/g (wet weight), mean of 0.17 μg/g, but only 17 % (9 of 54) exceeded the 0.30 μg/g (wet weight) USEPA fish muscle guideline recommended to protect human health. Concentrations of Hg in freshwater fish in this region generally decreased with increasing distance from the MAMD, where fish with the highest Hg concentrations were collected more proximal to the MAMD, whereas all fish collected most distal from Hg mines contained Hg below the 0.30 μg/g fish muscle guideline. Data in this study indicate some conversion of inorganic Hg to methyl-Hg and uptake of Hg in fish on the Paglia River, but less methylation of Hg and Hg uptake by freshwater fish in the larger Tiber River.

Binding of Hg by bacterial extracellular polysaccharide: a possible role in Hg tolerance.

Science.gov (United States)

Cruz, Kimberly; Guézennec, Jean; Barkay, Tamar

2017-07-01

Bacteria employ adaptive mechanisms of mercury (Hg) tolerance to survive in environments containing elevated Hg concentrations. The potential of extracellular polysaccharides (EPS) production by bacteria as a mechanism of Hg tolerance has not been previously investigated. The objectives of this study were to determine if bacterial EPS sorb Hg, and if so does sorption provide protection against Hg toxicity. Purified EPS with different chemical compositions produced by bacterial isolates from microbial mats in French Polynesian atolls and deep-sea hydrothermal vents were assessed for Hg sorption. The data showed that EPS sorbed up to 82% of Hg from solution, that this sorption was dependent on EPS composition, and that sorption was a saturable mechanism. Hg uptake capacities ranged from 0.005 to 0.454 mmol Hg/g for the different EPS. To determine if EPS production could alter bacterial Hg tolerance, Escherichia coli K-12 strains and their EPS defective mutants were tested by the disc inhibition assay. Mercury inhibited growth in a dose-dependent manner with wild-type strains having smaller (~1 mm), but statistically significant, zones of inhibition than various mutants and this difference was related to a 2-fold decline in the amount of EPS produced by the mutants relative to cell biomass. These experiments identified colanic acid and hexosamine as Hg-binding moieties in EPS. Together these data indicate that binding of Hg to EPS affords a low level of resistance to the producing bacteria.

3,9-Dithia-6-azaundecane-appended Iridium (III) Complex for the Selective Detection of Hg2+ in Aqueous Acetonitrile

International Nuclear Information System (INIS)

Ann, Jee Hye; Li, Yinan; Hyun, Myung Ho

2012-01-01

Detection of mercuric ion (Hg 2+ ) originated from natural or industrial sources is very important because it is extremely toxic even at low levels and causes serious environmental and health problems. Consequently, many efforts have been devoted to the development of sensitive chemosensors for the detection of Hg 2+ . For example, various fluorescent chemosensors based on rhodamine, nitrobenzoxadiazole, fluorescein, boradiazaindacene (BODIPY), dansyl, pyrene, or other fluorophores have been developed for the selective detection of Hg 2+ . While various fluorescent chemosensors for the selective detection of Hg 2+ have been developed, phosphorescent chemosensors for the selective detection of Hg 2+ are relatively rare. Among various phosphors, iridium (III) complexes with sulfur containing cyclometalated ligands have been used as phosphorescent chemosensors for the selective detection of Hg 2+ . Azacrown ether-appended iridium (III) complex developed in our laboratory has also been utilized as a phosphorescent chemosensor for the selective detection of Hg 2+ . As an another iridium (III) complex-based phosphorescent chemosensors for the selective detection of Hg 2+ , in this study, we wish to prepare iridium (III) complex containing two 3,9-dithia-6-azaundecane units as chelating ligands for metal ions. Some fluorophores containing 3,9-dithia-6-azaundecane unit have been successfully applied for the selective detection of Hg 2+ . In this instance, iridium (III) complex containing two 3,9-dithia-6-azaundecane units is expected to be useful as a phosphorescent chemosensor for the selective detection of Hg 2+ . Iridium (III) complex containing two 3,9-dithia-6-azaundecane units was prepared starting from 2-phenylpyridine according to the procedure shown in Scheme 1. 2-Phenylpyridine was transformed into chloride bridged dimeric iridium complex, [(ppy) 2 IrCl] 2 , via the reported procedure. By treating [(ppy) 2 IrCl] 2 with 4,4'-bis(bromomethyl)-2,2'-bipyridine, which

Three closely related 4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridines: synthesis, molecular conformations and hydrogen bonding in zero, one and two dimensions.

Science.gov (United States)

Sagar, Belakavadi K; Harsha, Kachigere B; Yathirajan, Hemmige S; Rangappa, Kanchugarakoppal S; Rathore, Ravindranath S; Glidewell, Christopher

2017-03-01

In each of 1-(4-fluorophenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C 21 H 19 F 4 N 3 O 2 S, (I), 1-(4-chlorophenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C 21 H 19 ClF 3 N 3 O 2 S, (II), and 1-(3-methylphenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C 22 H 22 F 3 N 3 O 2 S, (III), the reduced pyridine ring adopts a half-chair conformation with the methylsulfonyl substituent occupying an equatorial site. Although compounds (I) and (II) are not isostructural, having the space groups Pbca and P2 1 2 1 2 1 , respectively, their molecular conformations are very similar, but the conformation of compound (III) differs from those of (I) and (II) in the relative orientation of the N-benzyl and methylsulfonyl substituents. In compounds (II) and (III), but not in (I), the trifluoromethyl groups are disordered over two sets of atomic sites. Molecules of (I) are linked into centrosymmetric dimers by C-H...π(arene) hydrogen bonds, molecules of (II) are linked by two C-H...O hydrogen bonds to form ribbons of R 3 3 (18) rings, which are themselves further linked by a C-Cl...π(arene) interaction, and a combination of C-H...O and C-H...π(arene) hydrogen bonds links the molecules of (III) into sheets. Comparisons are made with the structures of some related compounds.

Chlor-alkali plant contamination of Aussa River sediments induced a large Hg-resistant bacterial community

Science.gov (United States)

Baldi, Franco; Marchetto, Davide; Gallo, Michele; Fani, Renato; Maida, Isabel; Covelli, Stefano; Fajon, Vesna; Zizek, Suzana; Hines, Mark; Horvat, Milena

2012-11-01

A closed chlor-alkali plant (CAP) discharged Hg for decades into the Aussa River, which flows into Marano Lagoon, resulting in the large-scale pollution of the lagoon. In order to get information on the role of bacteria as mercury detoxifying agents, analyses of anions in the superficial part (0-1 cm) of sediments were conducted at four stations in the Aussa River. In addition, measurements of biopolymeric carbon (BPC) as a sum of the carbon equivalent of proteins (PRT), lipids (LIP), and carbohydrates (CHO) were performed to correlate with bacterial biomass such as the number of aerobic heterotrophic cultivable bacteria and their percentage of Hg-resistant bacteria. All these parameters were used to assess the bioavailable Hg fraction in sediments and the potential detoxification activity of bacteria. In addition, fifteen isolates were characterized by a combination of molecular techniques, which permitted their assignment into six different genera. Four out of fifteen were Gram negative with two strains of Stenotrophomonas maltophilia, one Enterobacter sp., and one strain of Brevibacterium frigoritolerans. The remaining strains (11) were Gram positive belonging to the genera Bacillus and Staphylococcus. We found merA genes in only a few isolates. Mercury volatilization from added HgCl2 and the presence of plasmids with the merA gene were also used to confirm Hg reductase activity. We found the highest number of aerobic heterotrophic Hg-resistant bacteria (one order magnitude higher) and the highest number of Hg-resistant species (11 species out of 15) at the confluence of the River Aussa and Banduzzi's channel, which transport Hg from the CAP, suggesting that Hg is strongly detoxified [reduced to Hg(0)] at this location.

Bonding in Mercury-Alkali Molecules: Orbital-driven van der Waals Complexes

Directory of Open Access Journals (Sweden)

Dieter Cremer

2008-06-01

Full Text Available The bonding situation in mercury-alkali diatomics HgA (2Σ+ (A = Li, Na, K, Rb has been investigated employing the relativistic all-electron method Normalized Elimination of the Small Component (NESC, CCSD(T, and augmented VTZ basis sets. Although Hg,A interactions are typical of van der Waals complexes, trends in calculated De values can be explained on the basis of a 3-electron 2-orbital model utilizing calculated ionization potentials and the De values of HgA+(1Σ+ diatomics. HgA molecules are identified as orbital-driven van der Waals complexes. The relevance of results for the understanding of the properties of liquid alkali metal amalgams is discussed.

Synthesis and characterization of substituted Schiff-base ligands and their d(10) metal complexes: structure-induced luminescence tuning behaviors and applications in co-sensitized solar cells.

Science.gov (United States)

Dong, Yu-Wei; Fan, Rui-Qing; Wang, Ping; Wei, Li-Guo; Wang, Xin-Ming; Zhang, Hui-Jie; Gao, Song; Yang, Yu-Lin; Wang, Yu-Lei

2015-03-28

Nine IIB group complexes, [ZnL1Cl2] (Zn1), [CdL1Cl2]2 (Cd1), [HgL1Cl2] (Hg1), [ZnL2Cl2] (Zn2), [CdL2Cl2] (Cd2), [HgL2Cl2] (Hg2), [ZnL3Cl2] (Zn3), [CdL3Cl2] (Cd3) and [HgL3Cl2] (Hg3), have been synthesized from the corresponding ortho-(6-methoxy-pyridyl)(CH[double bond, length as m-dash]NAr) (where Ar = 2,6-iPr2C6H3, L1; 4-MeC6H4, L2; 2-OMeC6H4, L3) Schiff base and structurally characterized by elemental analysis, FT-IR, (1)H NMR and X-ray single-crystal analysis. Crystallographic studies reveal that the center metal of the complexes adopts a distorted tetrahedron geometry (except for Cd1 and Cd3, which display square pyramidal geometry) and C-HCl hydrogen bonds and ππ stacking interactions contribute to three-dimensional supramolecular structures. The series of complexes exhibit tunable luminescence from blue, through green, to light yellow by varying the temperature (298 K and 77 K), both in solution and in the solid state. Moreover, the quantum yields range from 0.027 to 0.422, and decrease according to the order of the periodic table (Zn > Cd > Hg). These results indicate that the center atom of the complexes leads to the geometry differences and hence to the tunable luminescence properties. Because Zn1-Zn3 exhibited higher molar extinction coefficients and a distinct absorption region, they were employed as co-sensitizers in ruthenium dye N719-sensitized photoanodes to deliver light-electricity efficiency enhancement, being assembled with counter-electrodes and electrolyte to prepare ZnX/N719 (where ZnX = Zn1, Zn2, and Zn3) co-sensitized dye sensitized solar cell (DSSC) devices. The prepared co-absorbent could overcome the deficiency of N719 absorption in the low-wavelength region of the visible spectrum, and offset competitive visible-light absorption of I3(-). Application of these prepared complexes in N719-sensitized solar cells enhanced their performance by 10-36%, which indicated a potential application of these types of complexes in DSSCs.

Overcoming phytoremediation limitations. A case study of Hg contaminated soil

Science.gov (United States)

Barbafieri, Meri

2013-04-01

Phytoremediation is a broad term that comprises several technologies to clean up water and soil. Despite the numerous articles appearing in scientific journals, very few field applications of phytoextraction have been successfully realized. The research here reported on Phytoextraction, the use the plant to "extract" metals from contaminated soil, is focused on implementations to overcome two main drawbacks: the survival of plants in unfavorable environmental conditions (contaminant toxicity, low fertility, etc.) and the often lengthy time it takes to reduce contaminants to the requested level. Moreover, to overcome the imbalance between the technology's potential and its drawbacks, there is growing interest in the use of plants to reduce only the fraction that is the most hazardous to the environment and human health, that is to target the bioavailable fractions of metals in soil. Bioavailable Contaminant Stripping (BCS) would be a remediation approach focused to remove the bioavailable metal fractions. BCS have been used in a mercury contaminated soil from Italian industrial site. Bioavailable fractions were determined by sequential extraction with H2O and NH4Cl.Combined treatments of plant hormone and thioligand to strength Hg uptake by crop plants (Brassica juncea and Helianthus annuus) were tested. Plant biomass, evapotranspiration, Hg uptake and distribution following treatments were compared. Results indicate the plant hormone, cytokinine (CK) foliar treatment, increased evapotranspiration rate in both tested plants. The Hg uptake and translocation in both tested plants increased with simultaneous addition of CK and TS treatments. B. juncea was the most effective in Hg uptake. Application of CK to plants grown in TS-treated soil lead to an increase in Hg concentration of 232% in shoots and 39% in roots with respect to control. While H. annuus gave a better response in plant biomass production, the application of CK to plants grown in TS-treated soil lead to

Decay from the superdeformed bands in 194Hg

International Nuclear Information System (INIS)

Henry, R.G.; Khoo, T.L.; Carpenter, M.P.

1995-01-01

Superdeformed bands in 194 H g were studied using the early implementation of Gammasphere. The response functions for the Ge detectors were measured for the first time as part of this experiment. Experiments were performed with both a backed target (where the residue stopped in the Au backing) and a thin target (where the residue recoiled into vacuum). This will permit measurements of the decay times of the quasicontinuum γrays. The spectrum in coincidence with the yrast SD band in 194 Hg reveals the same features as found in the quasicontinuum structure in 192 Hg. These features include: statistical γrays feeding the SD band, a pronounced E2 peak from transitions feeding the SD band, a Ml/E2 bump at low energies that is associated with the last stages of feeding of the superdeformed band, and a quasicontinuous distribution from γrays linking SD and normal states, including a sizable clustering of strength around 1.7 MeV. The remarkable similarity of the spectra coincident with SD bands in 192,194 Hg provides additional support for a statistical process for decay out of the SD states. This similarity contrasts with differences observed in the spectrum coincident with the SD band in the odd-even 191 Hg, confirming the predictions about the role of pairing (in normal states) in influencing the shape of the decay-out spectrum

Using Simple Science to Influence Corporate Responsibility—A Lesson from Mercury (Hg)

Science.gov (United States)

Filippelli, G. M.

2016-12-01

Mercury (Hg) is a powerful neurotoxin with wide environmental distribution. Typical population exposure to Hg comes from fish consumption, with fish being the final ecological endpoint of Hg magnification after a series of biogeochemical processes. The emission of Hg from coal-fired power plants has been strongly implicated as a key source of environmental Hg, and thus the target for various public policy initiatives in the US and abroad. We conducted a study of Hg distribution in surface soils over a broad area of central Indiana (US) to understand the major sources of Hg to local fish, and to assess the potential role of policy compliance in reducing Hg. We found a plume-like distribution pattern for soil Hg, with values exceeding 400 ppb Hg in the heart of the plume, and reducing to background concentration of about 30 ppb outside of the plume. The plume covered hundreds of square kilometers, was centered directly over the downtown area of Indianapolis (a city of roughly 1 million inhabitants), and could be roughly backtracked to a source in the southwest corner of the city, coincident with a large coal-fired utility plant that has the highest reported emissions of Hg in the area. Evidence of this link between a local source of Hg and net Hg deposition, with related implications for Hg runoff to local stream, biomagnification to fish, and fish consumption advisories was reported in regional newspapers and eventually published in scientific journals. But importantly, these findings were used by an NGO (the Beyond Coal campaign by Indiana branch of the Sierra Club) at a critical time to influence a decision by the owner of the power plant of whether to comply with the Hg policy rule by either adding higher technology scrubbing technologies to the plant or simply to convert the plant over to natural gas as the fuel source (a costlier choice upfront). The utility chose the latter option, and with the permanent elimination of Hg emissions, the net measurable effects

Heavy metal (Hg, Cd) effects on the ultrastructure of the chemoreceptor organs of the fish Alburnus alburnus

Energy Technology Data Exchange (ETDEWEB)

Hernadi, L.; Pevzner, R.; Salanki, J.

1986-01-01

The ultrastructural alterations of the olfactory organs and taste buds of the bleak were studied with scanning electron microscopy following treatment with different concentrations of mercury and cadmium. The metals were administered to the lake-water in the forms of HgCl/sub 2/ and CdCl/sub 2/. The concentrations (100 ug/1 Hg/sup + +/ and Cd/sup + +/, as well as 300 ug/1 Hg/sup + +/ and Cd/sup + +/) were kept constant. Samples were taken after exposures of 1 day, 2 days, 1 week, 2 weeks. The olfactory organs proved to be more sensitive than the taste buds to both metals upon any applied concentration and exposure times. The receptor cells of the olfactory organ showed different alterations to the different metals. The mercury treatment evoked dramatic decreases in the number of receptor cells and ciliated epithelial cells, while cadmium only brought forth unusual deformation and destruction of the receptor cells, without affecting the ciliated epithelial cells. On the taste buds mercury treatment affected the microridge system on the epithelial cells as well as the microvilliar system of the supporting and receptor cells. The effects showed duration and concentration dependency. Cadmium effects on the taste buds showed no structural alteration, only the mucous secretion increased over the surface of the taste buds.

A Neutron Scattering Study of Lattice Dynamics of HgTe and HgSe

DEFF Research Database (Denmark)

Kepa, H.; Giebultowicz, T.; Buras, B.

1982-01-01

The dispersion relations for the acoustic and optic phonons in HgTe and for the acoustic phonons in HgSe were determined by neutron inelastic scattering in three high symmetry directions. The effect of the free-carrier screening of the long-range electric field of LO phonons in HgTe was observed....... The formalism of the rigid ion model is used for numerical calculations of the phonon dispersion relations and the phonon densities of states in HgTe and HgSe....

Microbial Oxidation of Hg(0) - Its Effect on Hg Stable Isotope Fractionation and Methylmercury Production

Energy Technology Data Exchange (ETDEWEB)

Yee, Nathan [Rutgers Univ., New Brunswick, NJ (United States); Barkay, Tamar [Rutgers Univ., New Brunswick, NJ (United States); Reinfelder, John [Rutgers Univ., New Brunswick, NJ (United States)

2016-06-28

Mercury (Hg) associated with mixed waste generated by nuclear weapons manufacturing has contaminated vast areas of the Oak Ridge Reservation (ORR). Neurotoxic methylmercury (MeHg) has been formed from the inorganic Hg wastes discharged into headwaters of East Fork Poplar Creek (EFPC). Thus, understanding the processes and mechanisms that lead to Hg methylation along the flow path of EFPC is critical to predicting the impacts of the contamination and the design of remedial action at the ORR. In part I of our project, we investigated Hg(0) oxidation and methylation by anaerobic bacteria. We discovered that the anaerobic bacterium Desulfovibrio desulfuricans ND132 can oxidize elemental mercury [Hg(0)]. When provided with dissolved elemental mercury, D. desulfuricans ND132 converts Hg(0) to Hg(II) and neurotoxic methylmercury [MeHg]. We also demonstrated that diverse species of subsurface bacteria oxidizes dissolved elemental mercury under anoxic conditions. The obligate anaerobic bacterium Geothrix fermentans H5, and the facultative anaerobic bacteria Shewanella oneidensis MR-1 and Cupriavidus metallidurans AE104 can oxidize Hg(0) to Hg(II) under anaerobic conditions. In part II of our project, we established anaerobic enrichment cultures and obtained new bacterial strains from the DOE Oak Ridge site. We isolated three new bacterial strains from subsurface sediments collected from Oak Ridge. These isolates are Bradyrhizobium sp. strain FRC01, Clostridium sp. strain FGH, and a novel Negativicutes strain RU4. Strain RU4 is a completely new genus and species of bacteria. We also demonstrated that syntrophic interactions between fermentative bacteria and sulfate-reducing bacteria in Oak Ridge saprolite mediate iron reduction via multiple mechanisms. Finally, we tested the impact of Hg on denitrification in nitrate reducing enrichment cultures derived from subsurface sediments from the Oak Ridge site, where nitrate is a major contaminant. We showed that there is an inverse

Competition of hydrogen bonds and halogen bonds in complexes of hypohalous acids with nitrogenated bases.

Science.gov (United States)

Alkorta, Ibon; Blanco, Fernando; Solimannejad, Mohammad; Elguero, Jose

2008-10-30

A theoretical study of the complexes formed by hypohalous acids (HOX, X = F, Cl, Br, I, and At) with three nitrogenated bases (NH 3, N 2, and NCH) has been carried out by means of ab initio methods, up to MP2/aug-cc-pVTZ computational method. In general, two minima complexes are found, one with an OH...N hydrogen bond and the other one with a X...N halogen bond. While the first one is more stable for the smallest halogen derivatives, the two complexes present similar stabilities for the iodine case and the halogen-bonded structure is the most stable one for the hypoastatous acid complexes.

H2XP:OH2 Complexes: Hydrogen vs. Pnicogen Bonds

Directory of Open Access Journals (Sweden)

Ibon Alkorta

2016-02-01

Full Text Available A search of the Cambridge Structural Database (CSD was carried out for phosphine-water and arsine-water complexes in which water is either the proton donor in hydrogen-bonded complexes, or the electron-pair donor in pnicogen-bonded complexes. The range of experimental P-O distances in the phosphine complexes is consistent with the results of ab initio MP2/aug’-cc-pVTZ calculations carried out on complexes H2XP:OH2, for X = NC, F, Cl, CN, OH, CCH, H, and CH3. Only hydrogen-bonded complexes are found on the H2(CH3P:HOH and H3P:HOH potential surfaces, while only pnicogen-bonded complexes exist on H2(NCP:OH2, H2FP:OH2, H2(CNP:OH2, and H2(OHP:OH2 surfaces. Both hydrogen-bonded and pnicogen-bonded complexes are found on the H2ClP:OH2 and H2(CCHP:OH2 surfaces, with the pnicogen-bonded complexes more stable than the corresponding hydrogen-bonded complexes. The more electronegative substituents prefer to form pnicogen-bonded complexes, while the more electropositive substituents form hydrogen-bonded complexes. The H2XP:OH2 complexes are characterized in terms of their structures, binding energies, charge-transfer energies, and spin-spin coupling constants 2hJ(O-P, 1hJ(H-P, and 1J(O-H across hydrogen bonds, and 1pJ(P-O across pnicogen bonds.

Tracing historical trends of Hg in the Mississippi River using Hg concentrations and Hg isotopic compositions in a lake sediment core, Lake Whittington, Mississippi, USA

Science.gov (United States)

Gray, John E.; Van Metre, Peter C.; Pribil, Michael J.; Horowitz, Arthur J.

2015-01-01

Concentrations and isotopic compositions of mercury (Hg) in a sediment core collected from Lake Whittington, an oxbow lake on the Lower Mississippi River, were used to evaluate historical sources of Hg in the Mississippi River basin. Sediment Hg concentrations in the Lake Whittington core have a large 10-15 y peak centered on the 1960s, with a maximum enrichment factor relative to Hg in the core of 4.8 in 1966. The Hg concentration profile indicates a different Hg source history than seen in most historical reconstructions of Hg loading. The timing of the peak is consistent with large releases of Hg from Oak Ridge National Laboratory (ORNL), primarily in the late 1950s and 1960s. Mercury was used in a lithiumisotope separation process by ORNL and an estimated 128Mg (megagrams) of Hgwas discharged to a local stream that flows into the Tennessee River and, eventually, the Mississippi River. Mass balance analyses of Hg concentrations and isotopic compositions in the Lake Whittington core fit a binary mixing model with a Hg-rich upstream source contributing about 70% of the Hg to Lake Whittington at the height of the Hg peak in 1966. This upstream Hg source is isotopically similar to Hg isotope compositions of stream sediment collected downstream near ORNL. It is estimated that about one-half of the Hg released from the ORNL potentially reached the LowerMississippi River basin in the 1960s, suggesting considerable downstream transport of Hg. It is also possible that upstream urban and industrial sources contributed some proportion of Hg to Lake Whittington in the 1960s and 1970s.

A study of the local atomic structure in Hg0.80Cd0.20Te using x-ray diffuse scattering

International Nuclear Information System (INIS)

Quintana, J.P.; Cohen, J.B.

1993-01-01

The local atomic arrangements in a commercial n-type wafer of Hg 0.8 Cd 0.2 Te were investigated by measuring the diffuse x-ray scattering in two volumes in reciprocal space. A change in contrast between the two measurements was achieved by making one volume measurement at 12037 eV and a second volume measurement at 12270 eV, i.e., near the Hg L III edge. The difference between these two measurements yielded intensity only due to Hg--Hg, Hg--Te, and Hg--Cd pair interactions. In all three patterns, peak-like features were apparent at the forbidden Bragg peak positions on thermal diffuse scattering ridges that joined major Bragg reflections; these are primarily attributed to second order displacement effects on the mixed cation sublattice. The first two Warren-Cowley short-range order parameters were determined to be α 1/2 1/2 0 =-0.050(26) and α 110 =0.118(35). Simulations of the structure revealed small ordered regions with a preference for 3:1 Hg--Cd near neighbor configurations. The near-neighbor Hg--Te bonds contract from that calculated from the average crystal's lattice parameter, and this Hg--Te distance is less than the distance in HgTe

Solvothermal preparation of nano-β-HgS from a precursor, bis(dibenzyldithiocarbamato)mercury(II)

International Nuclear Information System (INIS)

Marimuthu, G.; Ramalingam, K.; Rizzoli, C.; Arivanandhan, M.

2012-01-01

A simple solvothermal method for the selective synthesis of β-HgS (meta cinnabar) nanoparticles in aqueous solutions is reported with bis(dibenzyldithiocarbamato)mercury(II) as the precursor. Crystal structure, size, morphology and composition of the products are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, high-resolution transmission electron microscopy (HRTEM), SAED and X-ray photoelectron spectroscopy (XPS). PXRD shows (111), (220), (200), (311), (222), (400), (331), (420) reflections characteristic of β-HgS. SEM micrographs display the spherical nature of the nano-β-HgS. EDX analysis showed the presence of Hg and S. HRTEM images indicate the spherical nature of the nanoparticles with their size in the range of 10–15 nm and the FFT pattern shows the crystalline nature of the spherical particles. The results are in agreement with those estimated from the XRD pattern. XPS signals observed at 162.6 and 162.8 eV are due to S2p 3/2 and S2p 1/2 electrons and the S2s was observed at 222.3 eV. The band gap of nano-β-HgS has been found to be 3.6 eV from the UV–visible spectral measurement. The blue-shifted band gap compared to the bulk HgS is a consequence of “size quantization” effect. A comprehensive characterization of the precursor by IR and single crystal X-ray crystallography shows the presence of HgS 4 coordination environment, with a distinct Hg–S bond asymmetry.

Anomalous H/D isotope effect on 35Cl NQR frequencies in piperidinium p-chlorobenzoate

International Nuclear Information System (INIS)

Nakano, Ryo; Honda, Hisashi; Kimura, Taiki; Nakata, Eiichi; Takamizawa, Satoshi; Noro, Sumiko; Ishimaru, Shin'ichi

2008-01-01

Anomalous isotope effects were detected in the 35 Cl nuclear quadrupole resonance (NQR) frequency of piperidinium p-chlrobenzoate (C 5 H 10 NH. ClC 6 H 4 COOH) by deuteration of hydrogen atoms. The atoms were determined to form two kinds of N-H...O type H-bonds in the crystal structure. Large frequency shifts of the 35 Cl resonance lines reaching 288 kHz at 77 K and 278 kHz at room temperature were caused upon deuteration, in spite of the fact that the Cl atoms in the molecule do not form hydrogen bonds in the crystal. Results of single crystal X-ray diffraction measurements and density-functional-theorem calculations suggest that a dihedral-angle change of 1.8 o between benzene and the piperidine ring contributes to 35 Cl NQR anomalous frequency shifts.

Electron beam induced Hg desorption and the electronic structure of the Hg depleted surface of Hg1/sub -//sub x/Cd/sub x/Te

International Nuclear Information System (INIS)

Shih, C.K.; Friedman, D.J.; Bertness, K.A.; Lindau, I.; Spicer, W.E.; Wilson, J.A.

1986-01-01

Auger electron spectroscopy (AES), x-ray photoemission spectroscopy (XPS), low energy electron diffraction (LEED), and angle-resolved ultraviolet photoemission spectroscopy (ARPES) were used to study the electron beam induced Hg desorption from a cleaved (110)Hg/sub 1-//sub x/Cd/sub x/Te surface and the electronic structure of the Hg depleted surface. Solid state recrystallized Hg/sub 1-//sub x/Cd/sub x/Te single crystals were used. It was found that the electron beam heating dominated the electron beam induced Hg desorption on Hg/sub 1-//sub x/Cd/sub x/Te. At the electron beam energy used, the electron beam heating extended several thousand angstroms deep. However, the Hg depletion saturated after a few monolayers were depleted of Hg atoms. At the initial stage of Hg loss (only 3%), the surface band bends upward (more p type). The ARPES spectrum showed the loss of some E vs k dispersion after 22% Hg atoms were removed from the surface region, and no dispersion was observed after 43% Hg atoms were removed. These results have important implications on the electronic structure of the surfaces and interfaces of which the stoichiometry is altered

Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism.

Science.gov (United States)

Boughlala, Zakaria; Fonseca Guerra, Célia; Bickelhaupt, F Matthias

2016-06-01

We have analyzed the structure and bonding of gas-phase Cl-X and [HCl-X](+) complexes for X(+)= H(+), CH3 (+), Li(+), and Na(+), using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl(-) and HCl for the various cations. The Cl-X bond becomes longer and weaker along X(+) = H(+), CH3 (+), Li(+), and Na(+). Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn-Sham molecular orbital (KS-MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities.

Superconductivity of Hg3NbF6 and Hg3TaF6

International Nuclear Information System (INIS)

Datars, W.R.; Morgan, K.R.; Gillespie, R.J.

1983-01-01

Low-temperature ac susceptibility measurements show that two new metallic compounds, Hg 3 TaF 6 and Hg 3 NbF 6 , are superconductors with a critical temperature of 7.0 K. Critical fields are 20% higher in Hg 3 TaF 6 but the temperature dependence of the critical field of the compounds is very similar down to 1.35 K. The critical field extrapolated to T = 0 K is 0.17 T for Hg 3 TaF 6 and 0.13 T for Hg 3 NbF 6

The NiCl2-Li-arene(cat.) combination: a versatile reducing mixture.

Science.gov (United States)

Alonso, Francisco; Yus, Miguel

2004-06-20

The NiCl2.2H2O-Li-arene(cat.) combination described in this tutorial review has shown to be a useful and versatile mixture able to reduce a broad range of functionalities bearing carbon-carbon multiple bonds, as well as carbon-heteroatom and heteroatom-heteroatom single and multiple bonds. The analogous deuterated combination, NiCl2.2D2O-Li-arene(cat.), allows the easy incorporation of deuterium in the reaction products. Alternatively, the anhydrous NiCl2-Li-arene (or polymer-supported arene)(cat.) system generates a highly reactive metallic nickel, which in the presence of molecular hydrogen at atmospheric pressure is able to catalyze the hydrogenation of almost the same type of functionalities mentioned above.

40 CFR 60.4112 - Changing Hg designated representative and alternate Hg designated representative; changes in...

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Changing Hg designated representative and alternate Hg designated representative; changes in owners and operators. 60.4112 Section 60.4112... Generating Units Hg Designated Representative for Hg Budget Sources § 60.4112 Changing Hg designated...

Native lignin for bonding fiber boards - evaluation of bonding mechanisms in boards made from laccase-treated fibers of beech (Fagus sylvatica)

DEFF Research Database (Denmark)

Felby, Claus; Thygesen, Lisbeth Garbrecht; Sanadi, Anand

2004-01-01

indicate that lignin extractives are precipitated on the fiber surfaces. The improved bonding may be related to several factors, linked to a more lignin rich fiber surface, such as surface molecular entanglements and covalent bonding between fibers through cross-linking of radicals. (C) 2004 Published......The auto-adhesion of beech wood (Fagus sylvatica) fibers can be enhanced by a pretreatment of the fibers with a phenol oxidase enzyme. The mechanism of enzymatic catalyzed bonding is linked to the generation of stable radicals in lignin by oxidation. Fiberboards made from laccase-treated fibers...

Pathways of CH3Hg and Hg ingestion in benthic organisms: an enriched isotope approach.

Science.gov (United States)

Taylor, Vivien F; Bugge, Deenie; Jackson, Brian P; Chen, Celia Y

2014-05-06

Mercury is a widespread contaminant in marine food webs, and identifying uptake pathways of mercury species, CH3Hg(+) and Hg(2+), into low trophic level organisms is important to understanding its entry into marine food webs. Enriched stable isotope tracers were used to study benthic vs. pelagic pathways of CH3Hg(+) and Hg(2+) uptake via food to the infaunal estuarine amphipod, Leptocheirus plumulosus. Algal cells differentially labeled with isotopically enriched CH3Hg(+) or Hg(2+) were added simultaneously to the sediment and water column of microcosms, and Hg species were monitored in amphipods and in sediment and water compartments. Methylation of Hg(2+) occurred during the course of the experiment, enhancing the uptake of Hg(2+) spikes. Trophic transfer of Hg from algae added to the water column was determined to be the major uptake route for amphipods, suggesting inputs of contaminated organic matter from the pelagic zone are important to mercury bioaccumulation even in organisms living in sediments.

Elastic, dynamical, and electronic properties of LiHg and Li3Hg: First-principles study

Science.gov (United States)

Wang, Yan; Hao, Chun-Mei; Huang, Hong-Mei; Li, Yan-Ling

2018-04-01

The elastic, dynamical, and electronic properties of cubic LiHg and Li3Hg were investigated based on first-principles methods. The elastic constants and phonon spectral calculations confirmed the mechanical and dynamical stability of the materials at ambient conditions. The obtained elastic moduli of LiHg are slightly larger than those of Li3Hg. Both LiHg and Li3Hg are ductile materials with strong shear anisotropy as metals with mixed ionic, covalent, and metallic interactions. The calculated Debye temperatures are 223.5 K and 230.6 K for LiHg and Li3Hg, respectively. The calculated phonon frequency of the T2 g mode in Li3Hg is 326.8 cm-1. The p states from the Hg and Li atoms dominate the electronic structure near the Fermi level. These findings may inspire further experimental and theoretical study on the potential technical and engineering applications of similar alkali metal-based intermetallic compounds.

ON THE DURABILITY OF RESIN-DENTIN BONDS: IDENTIFYING THE WEAKEST LINKS

Science.gov (United States)

Zhang, Zihou; Beitzel, Dylan; Mutluay, Mustafa; Tay, Franklin R.; Pashley, David H.; Arola, Dwayne

2015-01-01

Fatigue of resin-dentin adhesive bonds is critical to the longevity of resin composite restorations. Objectives The objectives were to characterize the fatigue and fatigue crack growth resistance of resin-dentin bonds achieved using two different commercial adhesives and to identify apparent “weak-links”. Methods Bonded interface specimens were prepared using Adper Single Bond Plus (SB) or Adper Scotchbond Multi-Purpose (SBMP) adhesives and 3M Z100 resin composite according to the manufacturers instructions. The stress-life fatigue behavior was evaluated using the twin bonded interface approach and the fatigue crack growth resistance was examined using bonded interface Compact Tension (CT) specimens. Fatigue properties of the interfaces were compared to those of the resin-adhesive, resin composite and coronal dentin. Results The fatigue strength of the SBMP interface was significantly greater than that achieved by SB (p≤0.01). Both bonded interfaces exhibited significantly lower fatigue strength than that of the Z100 and dentin. Regarding the fatigue crack growth resistance, the stress intensity threshold (ΔKth) of the SB interface was significantly greater (p≤0.01) than that of the SBMP, whereas the ΔKth of the interfaces was more than twice that of the parent adhesives. Significance Collagen fibril reinforcement of the resin adhesive is essential to the fatigue crack growth resistance of resin-dentin bonds. Resin tags that are not well hybridized into the surrounding intertubular dentin and/or poor collagen integrity are detrimental to the bonded interface durability. PMID:26169318

Ionothermal Synthesis, Structure, and Bonding of the Catena -Heteropolycation 1 ∞ [Sb 2 Se 2 ] +

KAUST Repository

Groh, Matthias F.

2015-01-26

The reaction of antimony and selenium in the Lewis-acidic ionic liquid 1-butyl-3-methyl-imidazolium tetrachloridoaluminate, [BMIm]Cl•4.7AlCl3, yielded dark-red crystals of [Sb2Se2]AlCl4. The formation starts above 160 ° C; at about 190 ° C, irreversible decomposition takes place. The compound crystallizes in the triclinic space group P 1¯ with a = 919.39(2) pm, b = 1137.92(3) pm, c = 1152.30(3) pm, α = 68.047(1)° , β = 78.115(1)° , γ = 72.530(1)° , and Z = 4. The structure is similar to that of [Sb2Te2]AlCl4 but has only half the number of crystallographically independent atoms. Polycationic chains 1∞ [Sb2Se2]+ form a pseudo-hexagonal arrangement along [011¯] ], which is interlaced by tetrahedral AlCl4 - groups. The catena-heteropolycation 1∞ [Sb2Se2]+ is a sequence of three different four-membered [Sb2Se2 ] rings. The chemical bonding scheme, established from the topological analysis of the real-space bonding indicator ELI-D, includes significantly polar covalent bonding in four-member rings withinthepolycation.Theringsareconnectedintoaninfinitechainbyhomonuclear non-polar Sb-Sb bonds and highly polar Sb-Se bonds. Half of the selenium atoms are three-bonded.

Triaxiality in the even-mass Hg isotopes: A discontinuity at 200Hg

International Nuclear Information System (INIS)

Morrison, I.; Spear, R.H.

1981-01-01

The mass dependence of excitation energies of the 2 + 1 , 2 + 2 , and 4 + 1 states of the even-mass Hg isotopes, and of some related B(E2) values, shows a marked discontinuity at 200 Hg. Analysis of B(E2;0 + 1 →2 + 1 ) values in terms of an extended interacting boson approximation model suggests that this discontinuity is due to a change in the proton and neutron distributions at 200 Hg. Apart from 200 Hg, the data favor γ-soft models rather than the rigid triaxial-rotor model

On the mean square displacements (MSD) of Hg and Te in HgTe

International Nuclear Information System (INIS)

Madhavan, Y.; Ramachandran, K.

1989-01-01

The mean square displacements (MSD) of Hg and Te in the perfect system of HgTe are worked out in the modified rigid ion model of Plumelle and Vandevyver. Also the MSD of Hg and Te neighbours around anion and cation vacancies in HgTe are worked out giving an active role for the vacancy following the theory of Maradudin et al. The results are compared with experimental values. (author)

Bonding in Mercury Molecules Described by the Normalized Elimination of the Small Component and Coupled Cluster Theory

NARCIS (Netherlands)

Cremer, Dieter; Kraka, Elfi; Filatov, Michael

2008-01-01

Bond dissociation energies (BDEs) of neutral HgX and cationic HgX(+) molecules range from less than a kcal mol(-1) to as much as 60 kcal mol(-1). Using NESCICCCSD(T) [normalized elimination of the small component and coupled-cluster theory with all single and double excitations and a perturbative

Hg(2+) detection using a phosphorothioate RNA probe adsorbed on graphene oxide and a comparison with thymine-rich DNA.

Science.gov (United States)

Huang, Po-Jung Jimmy; van Ballegooie, Courtney; Liu, Juewen

2016-06-07

Mercury is a highly toxic heavy metal and many DNA-based biosensors have been recently developed for Hg(2+) detection in water. Among them, thymine-rich DNA is the most commonly used for designing Hg(2+) sensors. However, the thymine-Hg(2+) interaction is strongly affected by the buffer conditions. We recently reported a molecular beacon containing phosphorothioate (PS)-modified RNA linkages that can be cleaved by Hg(2+). In this work, the fluorescence quenching and DNA adsorption properties of nano-sized graphene oxide (NGO) were used to develop a new sensor using the PS-RNA chemistry. Three DNA probes, containing one, three and five PS-RNA linkages, respectively, were tested. Finally, a fluorophore-labeled poly-A DNA with five PS-RNA linkages was selected and adsorbed by NGO. In the presence of Hg(2+), the fluorophore was released from NGO due to the cleavage reaction, resulting in a fluorescence enhancement. This sensor is highly selective for Hg(2+) with a detection limit of 8.5 nM Hg(2+). For comparison, a fluorophore-labeled poly-T DNA was also tested, which responded to Hg(2+) more slowly and was inhibited by high NaCl concentrations, while the PS-RNA probe was more tolerant to different buffer conditions. This work indicates a new method for interfacing DNA with NGO for Hg(2+) detection.

Quantum chemical study of the interaction of elemental Hg with small neutral, anionic and cationic Aun (n = 1–6) clusters

International Nuclear Information System (INIS)

Siddiqui, Shamoon Ahmad; Bouarissa, Nadir; Rasheed, Tabish; Al-Assiri, M.S.

2013-01-01

Graphical abstract: Binding energies as a function of cluster size for Au n Hg, Au n Hg + and Au n Hg − complexes. Highlights: ► Hg adsorption of neutral and charged Au n (n = 1–6) clusters has been discussed. ► Size and charged state of cluster significantly affect the Hg adsorption. ► Transfer of electron mainly found from s orbital of Hg to s orbital of Au. - Abstract: Adsorption of elemental mercury (Hg) on small neutral, cationic and anionic gold clusters (Au n , n = 1–6) has been studied by using the density functional theory (DFT). Results of this investigation show that frontier molecular orbital theory is a useful tool to predict the selectivity of Hg adsorption. It is found that adsorption of Hg on neutral, cationic and anionic Au n (n = 1–6) clusters are thermodynamically favorable. The binding energies of Hg on the cationic Au n clusters are greater than those on the neutral and anionic clusters. Natural bond orbital (NBO) analysis indicates that the flow of electrons in the neutral and charged clusters is mainly due to the s orbitals of Hg and Au. Results of NBO analysis also indicate that the binding energy of Hg with Au n clusters is directly proportional to the charge transfer, i.e. greater is the charge transfer, higher is the binding energy

Absence of Hg transpiration by shoot after Hg uptake by roots of six terrestrial plant species

International Nuclear Information System (INIS)

Greger, Maria; Wang Yaodong; Neuschuetz, Clara

2005-01-01

In this paper we investigated if, and to what extent, six different plant species accumulate, translocate and emit mercury (Hg) into the air. The Hg uptake by roots, distribution of Hg to the shoot and release of Hg via shoots of garden pea, spring wheat, sugar beet, oil-seed rape, white clover and willow were investigated in a transpiration chamber. The airborne Hg was trapped in a Hopcalite trap or a gold trap. Traps and plant materials were analysed for content of Hg by CVAAS. The results show that all plant species were able to take up Hg to a large extent from a nutrient solution containing 200 μg L -1 Hg. However, the Hg translocation to the shoot was low (0.17-2.5%) and the Hg that reached the leaves was trapped and no release of the absorbed Hg to the air was detected. - Mercury translocation to shoots was low

Theoretical study of X⁻ · 1 · YF (1 = triazine, X = Cl, Br and I, Y = H, Cl, Br, I, PH₂ and AsH₂): noncovalently electron-withdrawing effects on anion-arene interactions.

Science.gov (United States)

Chen, Yishan; Yao, Lifeng

2014-01-01

The ternary complexes X(-) · 1 · YF (1 = triazine, X = Cl, Br and I, Y = H, Cl, Br, I, PH2 and AsH2) have been investigated by MP2 calculations to understand the noncovalently electron-withdrawing effects on anion-arene interactions. The results indicate that in binary complexes (1 · X(-)), both weak σ-type and anion-π complexes can be formed for Cl(-) and Br(-), but only anion-π complex can be formed for I(-). Moreover, the hydrogen-bonding complex is the global minimum for all three halides in binary complexes. However, in ternary complexes, anion-π complex become unstable and only σ complex can retain in many cases for Cl(-) and Br(-). Anion-π complex keeps stable only when YF = HF. In contrast with binary complexes, σ complex become the global minimum for Cl(-) and Br(-) in ternary complexes. These changes in binding mode and strength are consistent with the results of covalently electron-withdrawing effects. However, in contrast with the covalently electron-withdrawing substituents, Cl(-) and Br(-) can attack the aromatic carbon atom to form a strong σ complex when the noncovalently electron-withdrawing effect is induced by halogen bonding. The binding behavior for I(-) is different from that for Cl(-) and Br(-) in two aspects. First, the anion-π complex for I(-) can also keep stable when the noncovalent interaction is halogen bonding. Second, the anion-π complex for I(-) is the global minimum when it can retain as a stable structure.

Hyperemesis Gravidarum (HG)

Science.gov (United States)

... Treatments Risks Complications Impact Take a Poll If HG continued past mid-pregnancy , did you experience complications ... Understanding Hyperemesis | Overview About Hyperemesis Gravidarum Hyperemesis gravidarum (HG) is a severe form of nausea and vomiting ...

Photoionization study of HgAr

International Nuclear Information System (INIS)

Linn, S.H.; Brom, J.M. Jr.; Tzeng, W.; Ng, C.Y.

1985-01-01

Photoionization efficiency data for HgAr + have been obtained in the region of 680--1240 A. The ionization energy of HgAr was determined to be 10.217 +- 0.012 eV. This value allows the calculation of the dissociation energy of HgAr + to be 0.228 +- 0.017 eV. The relative probabilities for the formation of HgAr + via the reactions Ar* x Hg or Hg* x Ar→ HgAr + +e - with Ar* and Hg* prepared in high Rydberg states in the energy range of 10.22--15.79 eV were estimated. Although the radii for the 3d and 5s Rydberg ortitals of Ar have similar values, the probabilities for the formation of HgAr + from Hg x Ar* with Ar* in the 5s[3/2] 0 1 and 5s'[1/2] 0 1 Rydberg states are substantially greater than those when the Ar* excited atoms are in the 3d[1/2] 0 1 , 3s[3/2] 0 1 , and 3d'[3/2] 0 1 Rydberg levels. The ratio for the cross sections for the formation of HgAr + from Hg x Ar* with Ar* formed in the 3d[1/2] 0 1 and 4d[1/2] 0 1 states, as well as that with Ar* prepared in the 5d[1/2] 0 1 and 6d[1/2] 0 1 states, were found to be consistent with the predictions of the previous impact parameter calculations

Halogen bonding: A new retention mechanism for the solid phase extraction of perfluorinated iodoalkanes

International Nuclear Information System (INIS)

Yan Xiaoqing; Shen Qianjin; Zhao Xiaoran; Gao Haiyue; Pang Xue; Jin Weijun

2012-01-01

Highlights: ► Halogen bonding (XB) is firstly utilised in solid phase extraction. ► The perfluorinated iodine alkanes can be extracted by C-I⋯Cl − halogen bonding. ► The C-I⋯Cl − halogen bond is well characterised by spectroscopy methods. ► The analytes with strong halogen-bonding abilities can be selectively extracted. - Abstract: For the first time, halogen-bonding interaction is utilised in the solid phase extraction of perfluorinated iodoalkane (PFI). Nine PFIs, as model analytes, were tested, and analyses by UV, 19 F NMR and Raman spectroscopies demonstrate that the PFIs are extracted by a strong anion exchange (SAX) sorbent from n-hexane due to the C-I⋯Cl − halogen-bonding interactions. The results also show that the adsorptivities of SAX for the diiodoperfluoro-alkanes (diiodo-PFIs) were much stronger than those for the perfluoroalkyl iodides (monoiodo-PFIs). Specifically, the recoveries for 1,6-diiodoperfluorohexane and 1,8-diiodoperfluorooctane were higher than 80% when 100 mL of sample spiked with a 5 ng mL −1 analyte mixture was extracted. Interestingly, SAX had no adsorption for hexafluorobenzene at all, which is known to be unable to form a halogen bond with Cl − . The analytical performance of the halogen bond-based SPE-GC–MS method for the diiodo-PFIs was also examined in soil samples. The sorbent SAX enabled the selective extraction of four diiodo-PFIs successfully from soil samples. The recoveries of the diiodo-PFIs extracted from 5 g soil sample at the 100 ng g −1 spike level were in the range of 73.2–93.8% except 26.8% for 1,2-diiodoperfluoroethane. The limit of detection varied from 0.02 to 0.04 ng g −1 in soil samples. Overall, this work reveals the great application potential of halogen bonding in the field of solid phase extraction to selectively extract compounds with strong halogen-bonding abilities.

Toxicity of selenium (Na sub 2 SeO sub 3 ) and mercury (HgCl sub 2 ) on the planarian Dugesia gonocephala

Energy Technology Data Exchange (ETDEWEB)

Congiu, A.M.; Casu, S.; Ugazio, G. (Istituto di Genetica (Italy))

1989-10-01

The toxicity of selenium (Na{sub 2}SeO{sub 3}) and mercury (HgCl{sub 2}) was determined by using a freshwater planarian which is particularly sensitive to pollution, and belongs to a fissiparous breed of Dugesia gonocephala. The mortality and fissiparity frequency of the subjects were studied. They were exposed to intense treatments (48 hours) or for medium to long periods of time (21 days) to either the single compounds or a combination of both, and were fed or fasting. The lethal effect of sodium selenite is correlated to the food intake, whereas the toxicity of mercurous chloride is probably the result of a fixative effect which does not depend on feeding. The 21-day treatment with the first compound has a non-negligible lethal effect which is probably due to an accumulation phenomenon. At doses where an antioxidant effect prevails, fissiparity is stimulated. On the other hand, the second compound reduces reproduction frequency to half the base values. Compared to the Paracentrotus lividus, the Dugesia gonocephala offers various advantages concerning toxicological experiments; besides being easier to handle in the laboratory, it is available all year round and is not subject to seasonal cycles. It is also more susceptible to the toxic effect of mercury, which is a common and highly toxic pollutant, than the sea urchin.

Forging Unsupported Metal-Boryl Bonds with Icosahedral Carboranes.

Science.gov (United States)

Saleh, Liban M A; Dziedzic, Rafal M; Khan, Saeed I; Spokoyny, Alexander M

2016-06-13

In contrast to the plethora of metal-catalyzed cross-coupling methods available for the installation of functional groups on aromatic hydrocarbons, a comparable variety of methods are currently not available for icosahedral carboranes, which are boron-rich three-dimensional aromatic analogues of aryl groups. Part of this is due to the limited understanding of the elementary steps for cross-coupling involving carboranes. Here, we report our efforts in isolating metal-boryl complexes to further our understanding of one of these elementary steps, oxidative addition. Structurally characterized examples of group 10 M-B bonds featuring icosahedral carboranes are completely unknown. Use of mercurocarboranes as a reagent to deliver M-B bonds saw divergent reactivity for platinum and palladium, with a Pt-B bond being isolated for the former, and a rare Pd-Hg bond being formed for the latter. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

3,9-Dithia-6-azaundecane-appended Iridium (III) Complex for the Selective Detection of Hg{sup 2+} in Aqueous Acetonitrile

Energy Technology Data Exchange (ETDEWEB)

Ann, Jee Hye; Li, Yinan; Hyun, Myung Ho [Pusan National Univ., Busan (Korea, Republic of)

2012-10-15

Detection of mercuric ion (Hg{sup 2+}) originated from natural or industrial sources is very important because it is extremely toxic even at low levels and causes serious environmental and health problems. Consequently, many efforts have been devoted to the development of sensitive chemosensors for the detection of Hg{sup 2+}. For example, various fluorescent chemosensors based on rhodamine, nitrobenzoxadiazole, fluorescein, boradiazaindacene (BODIPY), dansyl, pyrene, or other fluorophores have been developed for the selective detection of Hg{sup 2+}. While various fluorescent chemosensors for the selective detection of Hg{sup 2+} have been developed, phosphorescent chemosensors for the selective detection of Hg{sup 2+} are relatively rare. Among various phosphors, iridium (III) complexes with sulfur containing cyclometalated ligands have been used as phosphorescent chemosensors for the selective detection of Hg{sup 2+}. Azacrown ether-appended iridium (III) complex developed in our laboratory has also been utilized as a phosphorescent chemosensor for the selective detection of Hg{sup 2+}. As an another iridium (III) complex-based phosphorescent chemosensors for the selective detection of Hg{sup 2+}, in this study, we wish to prepare iridium (III) complex containing two 3,9-dithia-6-azaundecane units as chelating ligands for metal ions. Some fluorophores containing 3,9-dithia-6-azaundecane unit have been successfully applied for the selective detection of Hg{sup 2+}. In this instance, iridium (III) complex containing two 3,9-dithia-6-azaundecane units is expected to be useful as a phosphorescent chemosensor for the selective detection of Hg{sup 2+}. Iridium (III) complex containing two 3,9-dithia-6-azaundecane units was prepared starting from 2-phenylpyridine according to the procedure shown in Scheme 1. 2-Phenylpyridine was transformed into chloride bridged dimeric iridium complex, [(ppy){sub 2}IrCl]{sub 2}, via the reported procedure. By treating [(ppy){sub 2}IrCl

Crystal structures of N-(4-chlorophenyl-2-[(4,6-diaminopyrimidin-2-ylsulfanyl]acetamide and N-(3-chlorophenyl-2-[(4,6-diaminopyrimidin-2-ylsulfanyl]acetamide

Directory of Open Access Journals (Sweden)

S. Subasri

2017-04-01

Full Text Available The title compounds, C12H12ClN5OS, (I, and C12H12ClN5OS, (II, are 2-[(diaminopyrimidin-2-ylsulfanyl]acetamides. Compound (II, crystallizes with two independent molecules (A and B in the asymmetric unit. In each of the molecules, in both (I and (II, an intramolecular N—H...N hydrogen bond forms an S(7 ring motif. The pyrimidine ring is inclined to the benzene ring by 42.25 (14° in (I, and by 59.70 (16 and 62.18 (15° in molecules A and B, respectively, of compound (II. In the crystal of (I, molecules are linked by pairs of N—H...N hydrogen bonds, forming inversion dimers with an R22(8 ring motif. The dimers are linked via bifurcated N—H...O and C—H...O hydrogen bonds, forming corrugated layers parallel to the ac plane. In the crystal of (II, the A molecules are linked through N—H...O and N—H...Cl hydrogen bonds, forming layers parallel to (100. The B molecules are also linked by N—H...O and N—H...Cl hydrogen bonds, also forming layers parallel to (100. The parallel layers of A and B molecules are linked via N—H...N hydrogen bonds, forming a three-dimensional structure.

Anomalous H/D isotope effect on {sup 35}Cl NQR frequencies in piperidinium p-chlorobenzoate

Energy Technology Data Exchange (ETDEWEB)

Nakano, Ryo; Honda, Hisashi, E-mail: hhonda@yokohama-cu.ac.jp [Yokohama City University, Graduate School of Integrated Science (Japan); Kimura, Taiki [Yokohama City University, Faculty of Science (Japan); Nakata, Eiichi; Takamizawa, Satoshi; Noro, Sumiko [Yokohama City University, Graduate School of Integrated Science (Japan); Ishimaru, Shin' ichi [Tokyo Denki University, Department of Green and Sustainable Chemistry (Japan)

2008-01-15

Anomalous isotope effects were detected in the {sup 35}Cl nuclear quadrupole resonance (NQR) frequency of piperidinium p-chlrobenzoate (C{sub 5}H{sub 10}NH. ClC{sub 6}H{sub 4}COOH) by deuteration of hydrogen atoms. The atoms were determined to form two kinds of N-H...O type H-bonds in the crystal structure. Large frequency shifts of the {sup 35}Cl resonance lines reaching 288 kHz at 77 K and 278 kHz at room temperature were caused upon deuteration, in spite of the fact that the Cl atoms in the molecule do not form hydrogen bonds in the crystal. Results of single crystal X-ray diffraction measurements and density-functional-theorem calculations suggest that a dihedral-angle change of 1.8{sup o} between benzene and the piperidine ring contributes to {sup 35}Cl NQR anomalous frequency shifts.

Chronologically matched toenail-Hg to hair-Hg ratio: temporal analysis within the Japanese community (U.S.

Directory of Open Access Journals (Sweden)

Hinners Thomas

2012-10-01

Full Text Available Abstract Background Toenail-Hg levels are being used as a marker of methylmercury (MeHg exposure in efforts to associate exposure with effects such as cardiovascular disease. There is a need to correlate this marker with more established biomarkers that presently underlie existing dose–response relationships in order to compare these relationships across studies. Methods As part of the Arsenic Mercury Intake Biometric Study, toenail clippings were collected at three time points over a period of one year amongst females from within the population of Japanese living near Puget Sound in Washington State (US. Variability in temporal intra-individual toenail-Hg levels was examined and chronologically matched hair and toenail samples were compared to more accurately define the toxicokinetic variability of Hg levels observed between the two compartments. Results Mean toenail-Hg values (n=43 for the 1st, 2nd and 3rd visits were 0.60, 0.60 and 0.56 ng/mg. Correlations were as follows: r=0.92 between 1st and 2nd clinic visits, r=0.75 between 1st and 3rd visits and r=0.87 between 2nd and 3rd visits. With few exceptions, toenail-Hg values from any visit were within 50-150% of the individual’s mean toenail-Hg level. Nearly all participants had less than a two-fold change in toenail-Hg levels across the study period. A regression model of the relationship between toenail-Hg and hair-Hg (n = 41 levels representing the same time period of exposure, gave a slope (Hg ng/mg of 2.79 for hair relative to toenail (r=0.954. Conclusions A chronologically matched hair-Hg to toenail-Hg ratio has been identified within a population that consumes fish regularly and in quantity. Intra-individual variation in toenail-Hg levels was less than two-fold and may represent dietary-based fluctuations in body burden for individuals consuming various fish species with different contaminant levels. The chronologically matched ratio will be useful for relating MeHg exposure and

Recycling of rare earths from Hg-containing fluorescent lamp scraps by solid state chlorination; Rueckgewinnung Seltener Erden aus quecksilberbelasteten Leuchtstoffen mittels Feststoffchlorierung

Energy Technology Data Exchange (ETDEWEB)

Lorenz, Tom; Froehlich, Peter; Bertau, Martin [TU Bergakademie Freiberg (Germany); Golon, Katja [FNE Entsorgungsdienste GmbH, Freiberg (Germany)

2015-10-15

Solid state chlorination with NH{sub 4}Cl comprises a method for rare earth recycling apart from pyro- or hydrometallurgical strategies. The examined partially Hg-containing fluorescent lamp scraps are rich in rare earths like La, Ce, Tb and Gd, but especially in Y and Eu. By mixing with NH{sub 4}Cl and heating up to NH{sub 4}Cl decomposition temperature in a sublimation reactor, Y and Eu could be transferred selectively into their respective metal chlorides with high yields. The yield and selectivity depend on temperature and the ratio of NH{sub 4}Cl to fluorescent lamp scraps, which were varied systematically.

HCN Producing Bacteria Enable Sensing Of Non-Bioavailable Hg Species by the Whole Cell Biosensor

Science.gov (United States)

Horvat, M.; Rijavec, T.; Koron, N.; Lapanje, A.

2015-12-01

Bacteria play an important role in Hg transformation reactions. The production of cyanide (HCN) and other secondary metabolites seems to be key elements involved in these transformations. Current hypotheses link the role of HCN production to growth inhibition of nonHCN producing competitor organisms (role of an antimicrobial agent). Our past investigations showed that HCN production did not correlate with antimicrobial activity and since pK value of HCN is very high (pK = 9,21), it can be expected that most of the produced HCN is removed from the microenvironment. This way, the expected inhibitory concentrations can hardly be reached. Accordingly, we proposed a new concept, where the ability of complexation of transient metals by HCN served as a regulation process for the accessibility of micro-elements. In our study, we focused on the presence of HCN producing bacteria and carried it out in the Hg contaminated environment connected to the Idrija Mercury Mine, Slovenia. We characterised the isolates according to the presence of Hg resistance (HgR), level of HCN production and genetic similarities. In laboratory setups, using our merR whole cell based biosensor, we determined the transformation of low bioavailable Hg0 and HgS forms into bioavailable Hg by these HCN producing bacteria. We observed that HgR strains producing HCN had the highest impact on increased Hg bioavailability. In the proposed ecological strategy HgR HCN producing bacteria increase their competitive edge over non-HgR competitors through the increase of Hg toxicity. Due to their activity, Hg is made available to other organisms as well and thus enters into the ecosystem. Finally, using some of the characteristics of bacteria (e.g. Hg resistance genetic elements), we developed a fully automated sensing approach, combining biosensorics and mechatronics, to measure the bioavailability of Hg in situ.

Reactions of sigma-bonded organochromium(III)complexes

International Nuclear Information System (INIS)

Leslie, J.P. II.

1975-12-01

Three projects were carried out, each dealing with the kinetics and mechanism of reactions of sigma-bonded organochromium(III) complexes of the form (H 2 O) 5 CrR 2+ . Part I describes the kinetics of the reaction of dichloromethylchromium(III) ion with chromium(II) ion in aqueous acid. Part II deals with the radioexchange of 4-pyridinomethylchromium(III) ion with 51 Cr 2+ and the kinetics of formation of the organochromium species at 55 0 in 1 M H + . Part III deals with the reactions of Hg 2+ and CH 3 Hg + with a series of (H 2 O) 5 CrR 2+ complexes, in which R is an aliphatic alkyl group, a haloalkyl group, or an aralkyl group

Hg-coordination studies of oligopeptides containing cysteine, histidine and tyrosine by $^{199m}$Hg-TDPAC

CERN Document Server

Ctortecka, B; Mallion, S; Butz, T; Hoffmann, R

1999-01-01

In order to study the interaction of histidine- and tyrosine- containing peptide chains with Hg(II), the nuclear quadrupole interaction (NQI) of /sup 199m/Hg in the Hg complexes of the oligopeptides alanyl-alanyl-histidyl-alanyl-alanine-amid (AAHAA-NH /sub 2/) and alanyl-alanyl-tyrosyl-alanyl-alanine-amid (AAYAA-NH/sub 2/) was determined by time differential perturbed angular correlation and is compared with previous data on alanyl-alanyl-cysteyl-alanyl- alanyl (AACAA-OH). The /sup 199m/Hg-NQIs depend on the oligopeptide to Hg(II) stoichiometry and indicate that two-fold and four-fold coordinations occur for the bound Hg(II). (12 refs).

Probing the conformation of a conserved glutamic acid within the Cl- pathway of a CLC H+/Cl- exchanger.

Science.gov (United States)

Vien, Malvin; Basilio, Daniel; Leisle, Lilia; Accardi, Alessio

2017-04-03

The CLC proteins form a broad family of anion-selective transport proteins that includes both channels and exchangers. Despite extensive structural, functional, and computational studies, the transport mechanism of the CLC exchangers remains poorly understood. Several transport models have been proposed but have failed to capture all the key features of these transporters. Multiple CLC crystal structures have suggested that a conserved glutamic acid, Glu ex , can adopt three conformations and that the interconversion of its side chain between these states underlies H + /Cl - exchange. One of these states, in which Glu ex occupies the central binding site (S cen ) while Cl - ions fill the internal and external sites (S int and S ext ), has only been observed in one homologue, the eukaryotic cmCLC. The existence of such a state in other CLCs has not been demonstrated. In this study, we find that during transport, the prototypical prokaryotic CLC exchanger, CLC-ec1, adopts a conformation with functional characteristics that match those predicted for a cmCLC-like state, with Glu ex trapped in S cen between two Cl - ions. Transport by CLC-ec1 is reduced when [Cl - ] is symmetrically increased on both sides of the membrane and mutations that disrupt the hydrogen bonds stabilizing Glu ex in S cen destabilize this trapped state. Furthermore, inhibition of transport by high [Cl - ] is abolished in the E148A mutant, in which the Glu ex side chain is removed. Collectively, our results suggest that, during the CLC transport cycle, Glu ex can occupy S cen as well as the S ext position in which it has been captured crystallographically and that hydrogen bonds with the side chains of residues that coordinate ion binding to S cen play a role in determining the equilibrium between these two conformations. © 2017 Vien et al.

Detailed Assessment of the Kinetics of Hg-Cell Association, Hg Methylation, and Methylmercury Degradation in Several Desulfovibrio Species

Science.gov (United States)

Graham, Andrew M.; Bullock, Allyson L.; Maizel, Andrew C.; Elias, Dwayne A.

2012-01-01

The kinetics of inorganic Hg [Hg(II)i] association, methylation, and methylmercury (MeHg) demethylation were examined for a group of Desulfovibrio species with and without MeHg production capability. We employed a detailed method for assessing MeHg production in cultures, including careful control of medium chemistry, cell density, and growth phase, plus mass balance of Hg(II)i and MeHg during the assays. We tested the hypothesis that differences in Hg(II)i sorption and/or uptake rates drive observed differences in methylation rates among Desulfovibrio species. Hg(II)i associated rapidly and with high affinity to both methylating and nonmethylating species. MeHg production by Hg-methylating strains was rapid, plateauing after ∼3 h. All MeHg produced was rapidly exported. We also tested the idea that all Desulfovibrio species are capable of Hg(II)i methylation but that rapid demethylation masks its production, but we found this was not the case. Therefore, the underlying reason why MeHg production capability is not universal in the Desulfovibrio is not differences in Hg affinity for cells nor differences in the ability of strains to degrade MeHg. However, Hg methylation rates varied substantially between Hg-methylating Desulfovibrio species even in these controlled experiments and after normalization to cell density. Thus, biological differences may drive cross-species differences in Hg methylation rates. As part of this study, we identified four new Hg methylators (Desulfovibrio aespoeensis, D. alkalitolerans, D. psychrotolerans, and D. sulfodismutans) and four nonmethylating species (Desulfovibrio alcoholivorans, D. tunisiensis, D. carbinoliphilus, and D. piger) in our ongoing effort to generate a library of strains for Hg methylation genomics. PMID:22885751

Evidence of Hg-chain formation in HgxTiS2: a 199mHg-TDPAC study

International Nuclear Information System (INIS)

Troeger, W.; Butz, T.; Ouvrard, G.

1993-01-01

We determined the 199m Hg nuclear quadrupole interaction in the ''misfit'' or ''superstoichiometric'' compound Hg x TiS 2 by time differential perturbed angular correlation. A unique Hg-site with ν Q = 511(1) MHz and η = 0.410(4) was observed, irrespective of the Hg-uptake (2/3 ≤ x ≤ 4/3). We propose a model of Hg-Hg zig-zag chains which accounts for these observations as well as for the X-ray diffraction data. (orig.)

A Theoretical Study of the Oxidation of Hg0 to HgBr2 in the Troposphere

DEFF Research Database (Denmark)

Goodsite, M. E.; Plane, J. M C; Skov, H.

2004-01-01

The oxidation of elemental mercury (Hg0) to the divalent gaseous mercury dibromide (HgBr2) has been proposed to account for the removal of Hg0 during depletion events in the springtime Arctic. The mechanism of this process is explored in this paper by theoretical calculations of the relevant rate...... coefficients. Rice-Ramsberger-Kassel-Marcus (RRKM) theory, together with ab initio quantum calculations where required, are used to estimate the following: recombination rate coefficients of Hg with Br, I, and O; the thermal dissociation rate coefficient of HgBr; and the recombination rate coefficients of Hg......Br with Br, I, OH, and O2. A mechanism based on the initial recombination of Hg with Br, followed by the addition of a second radical (Br, I, or OH) in competition with thermal dissociation of HgBr, is able to account for the observed rate of Hg 0 removal, both in Arctic depletion events and at lower...

Distinct toxicological characteristics and mechanisms of Hg2+ and MeHg in Tetrahymena under low concentration exposure.

Science.gov (United States)

Liu, Cheng-Bin; Qu, Guang-Bo; Cao, Meng-Xi; Liang, Yong; Hu, Li-Gang; Shi, Jian-Bo; Cai, Yong; Jiang, Gui-Bin

2017-12-01

Inorganic divalent mercury complexes (Hg 2+ ) and monomethylmercury complexes (MeHg) are the main mercury species in aquatic systems and their toxicity to aquatic organisms is of great concern. Tetrahymena is a type of unicellular eukaryotic protozoa located at the bottom of food chain that plays a fundamental role in the biomagnification of mercury. In this work, the dynamic accumulation properties, toxicological characteristics and mechanisms of Hg 2+ and MeHg in five Tetrahymena species were evaluated in detail. The results showed that both Hg 2+ and MeHg were ingested and exhibited inhibitory effects on the proliferation or survival of Tetrahymena species. However, the ingestion rate of MeHg was significantly higher than that of Hg 2+ . The mechanisms responsible for the toxicity of MeHg and Hg 2+ were different, although both chemicals altered mitochondrial membrane potential (MMP). MeHg disrupted the integrity of membranes while Hg 2+ had detrimental effects on Tetrahymena as a result of the increased generation of reactive oxygen species (ROS). In addition, the five Tetrahymena species showed different capacities in accumulating Hg 2+ and MeHg, with T. corlissi exhibiting the highest accumulations. The study also found significant growth-promoting effect on T. corlissi under low concentration exposure (0.003 and 0.01μg Hg/mL (15 and 50nM)), suggesting different effect and mechanism that should be more closely examined when assessing the bioaccumulation and toxicity of mercury in aquatic ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

The Valency Theory: The Human Bond From A New Psychoanalytic Perspective

OpenAIRE

Med Hafsi

2008-01-01

The present paper discusses some psychoanalytical conceptions concerning what links people to each other, or the human bond. Psychoanalysis, can be regarded as a science dealing basically with, although not directly, the human bond or link linking the person with his external and internal objects. The fact that this bond is in perpetualtransformation, and therefore can be apprehended from different angles has led to various psychoanalytical conceptions or theories which are more complementary...

3-[(R-3,3-Dichloro-2-hydroxypropyl]-8-hydroxy-6-methoxy-1H-isochromen-1-one

Directory of Open Access Journals (Sweden)

Yong-Cheng Lin

2008-09-01

Full Text Available The title compound, C13H12Cl2O5, is an isocoumarin compound which has been isolated from the ethyl acetate extract of the fermentation broth of actinomycete Streptomyces sp. (V4 from the South China Sea. There are intra- and intermolecular hydrogen bonds and halogen bonds [Cl...Cl = 3.434 (2 Å; C—Cl...Cl = 121.6°]. The intermolecular O—H...O hydrogen bonds link molecules into chains along the b axis.

Synthesis and Catalytic Properties of Non-Cross-Linked and Cross-Linked Poly(alkylmethyldiallylammonium bromides) Having Decyl, Octyl, and Hexyl Side Chains

NARCIS (Netherlands)

Wang, G.J; Engberts, J.B.F.N.

1995-01-01

A family of non-cross-linked and cross-linked copolymers containing decyl, octyl, and hexyl groups as side chains ((CL)-CopolC1-10, (CL)-CopolC1-8, and (CL)-CopolC1-6, respectively) were synthesized by radical-initiated cyclocopolymerization of alkylmethyldiallylammonium bromide monomers without and

Hg and Pt-metals in meteorite carbon-rich residues - Suggestions for possible host phase for Hg

Science.gov (United States)

Jovanovic, S.; Reed, G. W., Jr.

1980-01-01

Carbon-rich and oxide residual phases have been isolated from Allende and Murchison by acid demineralization for the determination of their Hg, Pt-metal, Cr, Sc, Co, and Fe contents. Experimental procedures used eliminated the possibility of exogenous and endogenous contaminant trace elements from coprecipitating with the residues. Large enrichments of Hg and Pt-metals were found in Allende but not in Murchison residues. Hg-release profiles from stepwise heating experiments suggest a sulfide as the host for Hg. Diffusion calculations for Hg based on these experiments indicate an activation energy of 7-8 kcal/mol, the same as that for Hg in troilite from an iron meteorite. This is further support for a sulfide host phase for Hg. Equilibration of Hg with this phase at approximately 900 K is indicated. Reasons for the presence of Pt-metals in noncosmic relative abundances are explored.

Decay from the superdeformed bands in {sup 194}Hg

Energy Technology Data Exchange (ETDEWEB)

Henry, R.G.; Khoo, T.L.; Carpenter, M.P. [and others

1995-08-01

Superdeformed bands in {sup 194}H g were studied using the early implementation of Gammasphere. The response functions for the Ge detectors were measured for the first time as part of this experiment. Experiments were performed with both a backed target (where the residue stopped in the Au backing) and a thin target (where the residue recoiled into vacuum). This will permit measurements of the decay times of the quasicontinuum {gamma}rays. The spectrum in coincidence with the yrast SD band in {sup 194}Hg reveals the same features as found in the quasicontinuum structure in {sup 192}Hg. These features include: statistical {gamma}rays feeding the SD band, a pronounced E2 peak from transitions feeding the SD band, a Ml/E2 bump at low energies that is associated with the last stages of feeding of the superdeformed band, and a quasicontinuous distribution from {gamma}rays linking SD and normal states, including a sizable clustering of strength around 1.7 MeV. The remarkable similarity of the spectra coincident with SD bands in {sup 192,194}Hg provides additional support for a statistical process for decay out of the SD states. This similarity contrasts with differences observed in the spectrum coincident with the SD band in the odd-even {sup 191}Hg, confirming the predictions about the role of pairing (in normal states) in influencing the shape of the decay-out spectrum.

Spectroscopic study of the charge-transfer complexes TiCl4/styrene and TiCl4/polystyrene

Science.gov (United States)

Gonçalves, Norberto S.; Noda, Lúcia. K.

2017-10-01

In this work, solutions of TiCl4/styrene and TiCl4/polystyrene charge-transfer complexes in CHCl3 or CDCl3 were investigated by UV-vis, resonance Raman and 1H NMR spectroscopies in order to study their molecular and electronic structures. Both show a yellow colour due to absorption in the 400 nm region, related to a charge-transfer transition. In Raman spectra, as the excitation approaches the resonance region, the primary enhancement of aromatic ring modes was mainly observed, rather than intensification of the vinylic double-bond stretch. Under the experimental conditions it was observed that formation of polystyrene takes place, as showed by 1H NMR spectra, and the most significant interaction occurs at the aromatic ring, as supported by the results from interaction of TiCl4 with polystyrene, as indicated by the charge-transfer band and resonant intensification of the aromatic ring modes.

Hg/HgO electrode and hydrogen evolution potentials in aqueous sodium hydroxide

Energy Technology Data Exchange (ETDEWEB)

Nickell, Ryan A.; Zhu, Wenhua H.; Payne, Robert U.; Cahela, Donald R.; Tatarchuk, Bruce J. [Center for Microfibrous Materials Manufacturing, Department of Chemical Engineering, 230 Ross Hall, Auburn University, Auburn, AL 36849 (United States)

2006-10-27

The Hg/HgO electrode is usually utilized as a reference electrode in alkaline solution such as for development of an alkaline hydrogen electrode. The reference electrode provides a suitable reference point but is available from few commercial vendors and suffers from inadequate documentation on potential in varying electrolytes. A new numerical method uses activity, activity coefficients, and a few correlated empirical equations to determine the potential values in both dilute and concentrated sodium hydroxide solutions at temperatures of 0-90{sup o}C and at concentrations of 0.100-12.8mol kg{sub H{sub 2}O}{sup -1}. The computed potentials of the Hg/HgO electrodes versus a normal hydrogen electrode (NHE) at 25{sup o}C and 1atm are 0.1634V for 0.100m, 0.1077V for 1.00m, and 0.0976V for 1.45m NaOH solutions. The Hg/HgO reduction potential further changes to -0.0751V versus NHE and hydrogen evolution potential changes to -0.9916V versus NHE in a solution of 30.0wt.% NaOH at 80{sup o}C. The calculated values are compared with the measured data at 25 and 75{sup o}C. The experimental data agree well with the numerical values computed from the theoretical and empirical equations. (author)

Novel Hg2+-Induced Nephropathy in Rats and Mice Lacking Mrp2: Evidence of Axial Heterogeneity in the Handling of Hg2+ Along the Proximal Tubule

Science.gov (United States)

Zalups, Rudolfs K.; Joshee, Lucy; Bridges, Christy C.

2014-01-01

The role of the multi-resistance protein 2 (Mrp2) in the nephropathy induced by inorganic mercuric mercury (Hg2+) was studied in rats (TR−) and mice (Mrp2−/−), which lack functional Mrp2, and control animals. Animals were exposed to nephrotoxic doses of HgCl2. Forty-eight or 24 hours after exposure, tissues were harvested and analyzed for Hg content and markers of injury. Histological analyses revealed that the proximal tubular segments affected pathologically by Hg2+ were significantly different between Mrp2-deficient animals and controls. In the absence of Mrp2, cellular injury localized almost exclusively in proximal tubular segments in the subcapsular (S1) to midcortical regions (early S2) of the kidney. In control animals, cellular death occurred mainly in the proximal tubular segments in the inner cortex (late S2) and outer stripe of the outer medulla (S3). These differences in renal pathology indicate that axial heterogeneity exists along the proximal tubule with respect to how mercuric ions are handled. Total renal and hepatic accumulation of mercury was also greater in animals lacking Mrp2 than in controls, indicating that Mrp2 normally plays a significant role in eliminating mercuric ions from within proximal tubular cells and hepatocytes. Analyses of plasma creatinine, BUN, and renal expression of Kim-1 and Ngal tend to support the severity of the nephropathies detected histologically. Collectively, our findings indicate that a fraction of mercuric ions is normally secreted by Mrp2 in early portions of proximal tubules into the lumen and then is absorbed downstream in straight portions, where mercuric species typically induce toxic effects. PMID:25145654

Removal of Zn(II) and Hg(II) from aqueous solution on a carbonaceous sorbent chemically prepared from rice husk

International Nuclear Information System (INIS)

El-Shafey, E.I.

2010-01-01

A carbonaceous sorbent was prepared from rice husk via sulfuric acid treatment. Sorption of Zn(II) and Hg(II) from aqueous solution was studied varying time, pH, metal concentration, temperature and sorbent status (wet and dry). Zn(II) sorption was found fast reaching equilibrium within ∼2 h while Hg(II) sorption was slow reaching equilibrium within ∼120 h with better performance for the wet sorbent than for the dry. Kinetics data for both metals were found to follow pseudo-second order model. Sorption rate of both metals was enhanced with temperature rise. Activation energy, E a , for Zn(II) sorption, was ∼13.0 kJ/mol indicating a diffusion-controlled process ion exchange process, however, for Hg(II) sorption, E a was ∼54 kJ/mol indicating a chemically controlled process. Sorption of both metals was low at low pH and increased with pH increase. Sorption was much higher for Hg(II) than for Zn(II) with higher uptake for both metals by rising the temperature. Hg(II) was reduced to Hg(I) on the sorbent surface. This was confirmed from the identification of Hg 2 Cl 2 deposits on the sorbent surface by scanning electron microscopy and X-ray diffraction. However, no redox processes were observed in Zn(II) sorption. Sorption mechanism is discussed.

Hg concentrations and related risk assessment in coral reef crustaceans, molluscs and fish from New Caledonia

International Nuclear Information System (INIS)

Chouvelon, Tiphaine; Warnau, Michel; Churlaud, Carine; Bustamante, Paco

2009-01-01

There is a dramatic lack of data on Hg levels in marine organisms from tropical areas, and in particular from New Caledonia. For the first time, this study reports the total Hg concentrations in the tissues of several marine taxa from the New Caledonian lagoon. Seafood from both wild and farmed populations was considered. Hg concentrations varied over three orders of magnitudes according to factors including species, age (size/weight), trophic level, lifestyle and geographical origin. Taking into account the edible tissues, estimations of the amount of flesh that should be consumed by a 60-kg person to reach the Hg Provisional Tolerable Weekly Intake (PTWI) reveal acceptable risk for Human health in general. However, a risk was clearly identified in one site of the lagoon (i.e. Grande Rade) where high Hg concentrations were measured. These concentrations were higher than values reported in the current literature. - This work reports the first assessment of Hg levels in edible organisms from the New Caledonian lagoon and the associated risk linked to their consumption by Human

Hg concentrations and related risk assessment in coral reef crustaceans, molluscs and fish from New Caledonia

Energy Technology Data Exchange (ETDEWEB)

Chouvelon, Tiphaine [Littoral Environnement et Societes (LIENSs), UMR 6250, CNRS-Universite La Rochelle, 2 Rue Olympe de Gouges, F-17042 La Rochelle Cedex 01 (France); Warnau, Michel [International Atomic Energy Agency-Marine Environment Laboratories (IAEA-MEL), 4 Quai Antoine Ier, MC-98000 (Monaco); Churlaud, Carine [Federation de Recherche en Environnement pour le Developpement Durable (FR-EDD), FR CNRS 3097, Centre Commun d' Analyses, 5 Perspectives de l' Ocean, F-17071 La Rochelle Cedex 9 (France); Bustamante, Paco [Littoral Environnement et Societes (LIENSs), UMR 6250, CNRS-Universite La Rochelle, 2 Rue Olympe de Gouges, F-17042 La Rochelle Cedex 01 (France)], E-mail: pbustama@univ-lr.fr

2009-01-15

There is a dramatic lack of data on Hg levels in marine organisms from tropical areas, and in particular from New Caledonia. For the first time, this study reports the total Hg concentrations in the tissues of several marine taxa from the New Caledonian lagoon. Seafood from both wild and farmed populations was considered. Hg concentrations varied over three orders of magnitudes according to factors including species, age (size/weight), trophic level, lifestyle and geographical origin. Taking into account the edible tissues, estimations of the amount of flesh that should be consumed by a 60-kg person to reach the Hg Provisional Tolerable Weekly Intake (PTWI) reveal acceptable risk for Human health in general. However, a risk was clearly identified in one site of the lagoon (i.e. Grande Rade) where high Hg concentrations were measured. These concentrations were higher than values reported in the current literature. - This work reports the first assessment of Hg levels in edible organisms from the New Caledonian lagoon and the associated risk linked to their consumption by Human.

Determination of equilibrium phase composition in the Hg-HgTe-CdTe system by ''dew point'' method

International Nuclear Information System (INIS)

Vanyukov, A.V.; Krotov, I.I.; Ermakov, A.I.

1978-01-01

Using the ''dew point'' method a study has been made of the equilibrium composition of the solid and liquid phases in the Hg-HgTe-CdTe system at 404, 435 and 454 deg C. It has been pointed out that crystallization of cadmium-rich solid solutions of Cdsub(x)Hgsub(1-x) Te takes place from a liquid phase with a much higher concentration of Hg. The activity of Hg in the liquid phase increases along the liquidus isotherm in the direction from section Hg-HgTe to section HgCdTe in accordance with the increase of its concentration. An increase in activity of Hg in the solid phase of Cdsub(x)Hgsub(1-x)Te has been noted with the reduction of its concentration

Crystal structure, vibrational spectra, optical and DFT studies of bis (3-azaniumylpropyl) azanium pentachloroantimonate (III) chloride monohydrate (C6H20N3)SbCl5·Cl·H2O

Science.gov (United States)

Ahmed, Houssem Eddine; Kamoun, Slaheddine

2017-09-01

The crystal structure of (C6H20N3)SbCl5·Cl·H2O is built up of [NH3(CH2)3NH2(CH2)3NH3]3 + cations, [SbCl5]2 - anions, free Cl- anions and neutral water molecules connected together by Nsbnd H ⋯ Cl, Nsbnd H ⋯ O and Osbnd H ⋯ Cl hydrogen bonds. The optical band gap determined by diffuse reflection spectroscopy (DRS) is 3.78 eV for a direct allowed transition. Optimized molecular geometry, atomic Mulliken charges, harmonic vibrational frequencies, HOMO-LUMO and related molecular properties of the (C6H20N3)SbCl5·Cl·H2O compound were calculated by Density functional theory (DFT) using B3LYP method with GenECP sets. The calculated structural parameters (bond lengths and angles) are in good agreement with the experimental XRD data. The vibrational unscaled wavenumbers were calculated and scaled by a proper scaling factor of 0.984. Acceptable consistency was observed between calculated and experimental results. The assignments of wavenumbers were made on the basis of potential energy distribution (PED) using Vibrational Energy Distribution Analysis (VEDA) software. The HOMO-LUMO study was extended to calculate various molecular parameters like ionization potential, electron affinity, global hardness, electro-chemical potential, electronegativity and global electrophilicity of the given molecule.

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

Energy Technology Data Exchange (ETDEWEB)

Rajeshwari, A.; Karthiga, D.; Chandrasekaran, Natarajan; Mukherjee, Amitava, E-mail: amit.mookerjea@gmail.com

2016-10-01

An efficient detection method for Hg (II) ions at physiological pH (pH 7.4) was developed using tween 20-modified gold nanorods (NRs) in the presence of dithiothreitol (DTT). Thiol groups (-SH) at the end of DTT have a higher affinity towards gold atoms, and they can covalently interact with gold NRs and leads to their aggregation. The addition of Hg(II) ions prevents the aggregation of gold NRs due to the covalent bond formation between the -SH group of DTT and Hg(II) ions in the buffer system. The changes in the longitudinal surface plasmon resonance peak of gold NRs were characterized using a UV–visible spectrophotometer. The absorption intensity peak of gold NRs at 679 nm was observed to reduce after interaction with DTT, and the absorption intensity was noted to increase by increasing the concentration of Hg(II) ions. The TEM analysis confirms the morphological changes of gold NRs before and after addition of Hg(II) ions in the presence of DTT. Further, the aggregation and disaggregation of gold NRs were confirmed by particle size and zeta potential analysis. The developed method shows an excellent linearity (y = 0.001 x + 0.794) for the graph plotted between the absorption ratio and Hg(II) concentration (1 to 100 pM) under the optimized conditions. The limit of detection was noted to be 0.42 pM in the buffer system. The developed method was tested in simulated body fluid, and it was found to have a good recovery rate. - Highlights: • Tween-20 modified gold NRs used as a probe for Hg(II) at physiological pH. • TEM, particle size and surface charge analysis confirm the aggregation and • disaggregation of NRs • The sensitivity of the probe for Hg(II) ions detection was 0.42 pM. • Hg(II) estimation in simulated body fluids with good recovery.

Effects of dilute aqueous NaCl solution on caffeine aggregation

Energy Technology Data Exchange (ETDEWEB)

Sharma, Bhanita; Paul, Sandip, E-mail: sandipp@iitg.ernet.in [Department of Chemistry, Indian Institute of Technology, Guwahati 781039, Assam (India)

2013-11-21

The effect of salt concentration on association properties of caffeine molecule was investigated by employing molecular dynamics simulations in isothermal-isobaric ensemble of eight caffeine molecules in pure water and three different salt (NaCl) concentrations, at 300 K temperature and 1 atm pressure. The concentration of caffeine was taken almost at the solubility limit. With increasing salt concentration, we observe enhancement of first peak height and appearance of a second peak in the caffeine-caffeine distribution function. Furthermore, our calculated solvent accessible area values and cluster structure analyses suggest formation of higher order caffeine cluster on addition of salt. The calculated hydrogen bond properties reveal that there is a modest decrease in the average number of water-caffeine hydrogen bonds on addition of NaCl salt. Also observed are: (i) decrease in probability of salt contact ion pair as well as decrease in the solvent separated ion pair formation with increasing salt concentration, (ii) a modest second shell collapse in the water structure, and (iii) dehydration of hydrophobic atomic sites of caffeine on addition of NaCl.

Effects of dilute aqueous NaCl solution on caffeine aggregation

International Nuclear Information System (INIS)

Sharma, Bhanita; Paul, Sandip

2013-01-01

The effect of salt concentration on association properties of caffeine molecule was investigated by employing molecular dynamics simulations in isothermal-isobaric ensemble of eight caffeine molecules in pure water and three different salt (NaCl) concentrations, at 300 K temperature and 1 atm pressure. The concentration of caffeine was taken almost at the solubility limit. With increasing salt concentration, we observe enhancement of first peak height and appearance of a second peak in the caffeine-caffeine distribution function. Furthermore, our calculated solvent accessible area values and cluster structure analyses suggest formation of higher order caffeine cluster on addition of salt. The calculated hydrogen bond properties reveal that there is a modest decrease in the average number of water-caffeine hydrogen bonds on addition of NaCl salt. Also observed are: (i) decrease in probability of salt contact ion pair as well as decrease in the solvent separated ion pair formation with increasing salt concentration, (ii) a modest second shell collapse in the water structure, and (iii) dehydration of hydrophobic atomic sites of caffeine on addition of NaCl

Amidolysis of Oxirane: Effect of Protein Type, Oils, and ZnCl2 on the Rheological Properties of Cross-Linked Protein and Oxirane

Directory of Open Access Journals (Sweden)

A. A. Mohamed

2018-01-01

Full Text Available Amidolysis of oxirane group of epoxidized sesame, sunflower, and cottonseed oils was achieved by reaction with primary amide of millet and gluten proteins. Gluten is a coproduct of wheat starch industry and available commercially. Millet is a major part of the staple food of the semiarid region of the tropics. Gluten is a mixture of glutenins and gliadins rich in glutamine residues; however, millet is rich in glutamine and leucine. We have taken advantage of the available primary amide of glutamine for cross-linking with the oxirane of sunflower, sesame, and cottonseed oils under controlled conditions to give a resin of amidohydroxy of gluten and millet proteins. Cross-linking gave a resin with a wide range of textural properties. The texture of the resin was dependent on the source of the oxirane, the amide group, and the amount of the catalyst (ZnCl2. The thermal properties, textural, solubility, and rheological properties were determined as well as the reaction time. The data showed direct relationships between the ZnCl2, nature of oil, and protein type and the properties of the final resin. Consistently, the results pointed to similarity among the outcome of the reactions between sesame and sunflower oils. Depending on the amount of ZnCl2, the texture of the resin can range from viscose to rubbery. The reaction time was influenced by oxirane source, protein type, and catalyst and ranged from 30 min to 4 hr.

Adsorption of small NaCl clusters on surfaces of silicon nanostructures

International Nuclear Information System (INIS)

Amsler, Maximilian; Alireza Ghasemi, S; Goedecker, Stefan; Neelov, Alexey; Genovese, Luigi

2009-01-01

We have studied possible adsorption geometries of neutral NaCl clusters on the disordered surface of a large silicon model tip used in non-contact atomic force microscopy. The minima hopping method was used to determine low energy model tip configurations as well as ground state geometries of isolated NaCl clusters. The combined system was treated with density functional theory. Alkali halides have proven to be strong structure seekers and tend to form highly stable ground state configurations whenever possible. The favored adsorption geometry for four Na and four Cl atoms was found to be an adsorption of four NaCl dimers due to the formation of Cl-Si bonds. However, for larger NaCl clusters, the increasing energy required to dissociate the cluster into NaCl dimers suggests that adsorption of whole clusters in their isolated ground state configuration is preferred.

Mercury stabilization in chemically bonded phosphate ceramics

International Nuclear Information System (INIS)

Wagh, A. S.; Singh, D.; Jeong, S. Y.

2000-01-01

Mercury stabilization and solidification is a significant challenge for conventional stabilization technologies. This is because of the stringent regulatory limits on leaching of its stabilized products. In a conventional cement stabilization process, Hg is converted at high pH to its hydroxide, which is not a very insoluble compound; hence the preferred route for Hg sulfidation to convert it into insoluble cinnabar (HgS). Unfortunately, efficient formation of this compound is pH-dependent. At a high pH, one obtains a more soluble Hg sulfate, in a very low pH range, insufficient immobilization occurs because of the escape of hydrogen sulfide, while efficient formation of HgS occurs only in a moderately acidic region. Thus, the pH range of 4 to 8 is where stabilization with Chemically Bonded Phosphate Ceramics (CBPC) is carried out. This paper discusses the authors experience on bench-scale stabilization of various US Department of Energy (DOE) waste streams containing Hg in the CBPC process. This process was developed to treat DOE's mixed waste streams. It is a room-temperature-setting process based on an acid-base reaction between magnesium oxide and monopotassium phosphate solution that forms a dense ceramic within hours. For Hg stabilization, addition of a small amount ( 2 S or K 2 S is sufficient in the binder composition. Here the Toxicity Characteristic Leaching Procedure (TCLP) results on CBPC waste forms of surrogate waste streams representing secondary Hg containing wastes such as combustion residues and Delphi DETOXtrademark residues are presented. The results show that although the current limit on leaching of Hg is 0.2 mg/L, the results from the CBPC waste forms are at least one order lower than this stringent limit. Encouraged by these results on surrogate wastes, they treated actual low-level Hg-containing mixed waste from their facility at Idaho. TCLP results on this waste are presented here. The efficient stabilization in all these cases is

In vitro Assessment of Hg Toxicity in Hepatocytes from Heat-Stressed Atlantic Salmon.

Science.gov (United States)

Olsvik, Pål A; Waagbø, Rune; Hevrøy, Ernst M; Remø, Sofie C; Søfteland, Liv

2016-11-01

Global warming may alter the bioavailability of contaminants in aquatic environments. In this work, mercury (Hg 2+ ) toxicity was studied in cells obtained from Atlantic salmon smolt kept at 15 °C (optimal growth temperature) for 3 months or at a stepwise increase to 20 °C (temperature-stress) during 3 months prior to cell harvest to evaluate whether acclimation temperature affects Hg toxicity. To examine possible altered dietary requirements in warmer seas, one group of fish following the stepwise temperature regimes was fed a diet spiked with antioxidants. Atlantic salmon hepatocytes were exposed in vitro to 0, 1.0, or 100 μM Hg 2+ for 48 h. Cytotoxicity, determined as electrical impedance changes with the xCELLigence system, and transcriptional responses, determined with RT-qPCR, were assessed as measures of toxicity. The results showed that inorganic Hg at a concentration up to 100 μM is not cytotoxic to Atlantic salmon hepatocytes. Significance and directional responses of the 18 evaluated target genes suggest that both Hg and temperature stress affected the transcription of genes encoding proteins involved in the protection against ROS-generated oxidative stress. Both stressors also affected the transcription of genes linked to lipid metabolism. Spiking the diet with antioxidants resulted in higher concentrations of Se and vitamin C and reduced concentration of Hg in the liver in vivo, but no interactions were seen between the dietary supplementation of antioxidants and Hg toxicity in vitro. In conclusion, no evidence was found suggesting that inorganic Hg is more toxic in cells harvested from temperature-stressed fish.

Relativistic effects in bonding and dipole moments for the diatomic hydrides of the sixth-row heavy elements

International Nuclear Information System (INIS)

Ramos, A.F.; Pyper, N.C.; Malli, G.L.

1988-01-01

Ab initio Dirac-Fock (DF) and nonrelativistic-limit (NRL) wave functions and dipole moments are calculated to investigate the bonding characteristics and the relativistic effects in the systems HgH + , TlH, PbH + , and BiH. The dipole moment of AuH is evaluated using the DF self-consistent field and relativistic configuration-interaction wave functions obtained by G. L. Malli and N. C. Pyper [Proc. R. Soc. London, Ser. A 407, 377 (1986)]. Contour plots of relativistic molecular orbital densities and difference density maps are presented to illustrate the arrangement of electronic charge in these systems. It is found that the 5d orbitals are involved in the bonding of HgH + , whereas they do not play a significant role in TlH and PbH + . The relativistic calculations predict HgH + , TlH, and PbH + to be bound. The nonrelativistic-limit wave functions predict HgH + and BiH to be unbound but TlH and PbH + to be bound. It is also found that the calculated dipole moments using the DF and the NRL wave functions for these heavy systems differ significantly in magnitude, and in some cases even in the sign

The interaction of mercury with halogenated graphene

Science.gov (United States)

Kirchofer, Abigail; Sasmaz, Erdem; Wilcox, Jennifer

2011-03-01

The interaction of mercury with halogenated graphene was studied using plane-wave density functional theory. Various configurations of H, Hg, O and Br or Cl on the zigzag edge sites of graphene were investigated. Although Hg-Br (or -Cl) complexes were found to be stable on the surface, the most stable configurations found were those with Hg adjacent to O. The surface atoms Hg, O, and Br tend to repel each other during geometric optimization, moving towards an H atom nearest-neighbor where possible. The strength of the Hg-graphene interaction is very sensitive to the local environment. The Hg-graphene binding energy is strongest when the Hg is located next to a surface O but not immediately next to a bound Br. DOS analysis revealed that Hg adsorption involves a gain in Hg 6 p-states and a loss in Hg 5 s electron density, resulting in an oxidized surface-bound Hg complex. DOS analysis suggests that Br strengthens the Hg-graphene interaction by modifying the surface carbon electron density; however, when Br is adjacent to Hg, a direct Hg-Br interaction weakens the Hg-C bond. These investigations provide insight into the mechanism associated with enhanced Hg adsorption on Br-functionalized carbon materials for Hg emissions reductions from coal-fired power plant applications. The authors acknowledge the financial support by Electric Power Research Institute (EPRI).

Crystal structure of the Hg4SiS6 and Hg4SiSe6 compounds

International Nuclear Information System (INIS)

Gulay, L.D.; Olekseyuk, I.D.; Parasyuk, O.V.

2002-01-01

The crystal structures of Hg 4 SiS 6 and Hg 4 SiSe 6 compounds were investigated using X-ray powder diffraction. These compounds crystallize in the monoclinic Cc space group with the lattice parameters a=1.23020(5), b=0.71031(4), c=1.22791(4) nm, β=109.721(3) deg. for Hg 4 SiS 6 and a=1.28110(4), b=0.74034(4), c=1.27471(1) nm, β=109.605(3) deg. for Hg 4 SiSe 6 . Atomic parameters were refined in the isotropic approximation (R I =0.0571 and R I =0.0555 for the Hg 4 SiS 6 and Hg 4 SiSe 6 , respectively)

UV photolysis of 4-iodo-, 4-bromo-, and 4-chlorophenol: Competition between C–Y (Y = halogen) and O–H bond fission

International Nuclear Information System (INIS)

Sage, Alan G.; Oliver, Thomas A. A.; King, Graeme A.; Murdock, Daniel; Harvey, Jeremy N.; Ashfold, Michael N. R.

2013-01-01

The wavelength dependences of C–Y and O–H bond fission following ultraviolet photoexcitation of 4-halophenols (4-YPhOH) have been investigated using a combination of velocity map imaging, H Rydberg atom photofragment translational spectroscopy, and high level spin-orbit resolved electronic structure calculations, revealing a systematic evolution in fragmentation behaviour across the series Y = I, Br, Cl (and F). All undergo O–H bond fission following excitation at wavelengths λ≲ 240 nm, on repulsive ((n/π)σ*) potential energy surfaces (PESs), yielding fast H atoms with mean kinetic energies ∼11 000 cm −1 . For Y = I and Br, this process occurs in competition with prompt C–I and C–Br bond cleavage on another (n/π)σ* PES, but no Cl/Cl* products unambiguously attributable to one photon induced C–Cl bond fission are observed from 4-ClPhOH. Differences in fragmentation behaviour at longer excitation wavelengths are more marked. Prompt C–I bond fission is observed following excitation of 4-IPhOH at all λ≤ 330 nm; the wavelength dependent trends in I/I* product branching ratio, kinetic energy release, and recoil anisotropy suggest that (with regard to C–I bond fission) 4-IPhOH behaves like a mildly perturbed iodobenzene. Br atoms are observed when exciting 4-BrPhOH at long wavelengths also, but their velocity distributions suggest that dissociation occurs after internal conversion to the ground state. O–H bond fission, by tunnelling (as in phenol), is observed only in the cases of 4-FPhOH and, more weakly, 4-ClPhOH. These observed differences in behaviour can be understood given due recognition of (i) the differences in the vertical excitation energies of the C–Y centred (n/π)σ* potentials across the series Y = I < Br < Cl and the concomitant reduction in C–Y bond strength, cf. that of the rival O–H bond, and (ii) the much increased spin-orbit coupling in, particularly, 4-IPhOH. The present results provide (another) reminder of the

Manifestations of Kitaev physics in thermodynamic properties of hexagonal iridates and α-RuCl3

Science.gov (United States)

Tsirlin, Alexander

Kitaev model is hard to achieve in real materials. Best candidates available so far are hexagonal iridates M2IrO3 (M = Li and Na) and the recently discovered α-RuCl3 featuring hexagonal layers coupled by weak van der Waals bonding. I will review recent progress in crystal growth of these materials and compare their thermodynamic properties. Both hexagonal iridates and α-RuCl3 feature highly anisotropic Curie-Weiss temperatures that not only differ in magnitude but also change sign depending on the direction of the applied magnetic field. Néel temperatures are largely suppressed compared to the energy scale of the Curie-Weiss temperatures. These experimental observations will be linked to features of the electronic structure and to structural peculiarities associated with deviations from the ideal hexagonal symmetry. I will also discuss how the different nature of ligand atoms affects electronic structure and magnetic superexchange. This work has been done in collaboration with M. Majumder, M. Schmidt, M. Baenitz, F. Freund, and P. Gegenwart.

Biosynthesis, purification and characterization of commercial enzyme by penicillium expansum link

International Nuclear Information System (INIS)

Ahmed, K.; Valeem, E.E.

2015-01-01

Ever growing biotechnological industry has motivated the research towards the comprehensive survey of microorganisms, which could be used in extreme conditions of industry. In the present work optimization parameters in submerged fermentation, purification and characterization of invertase from Penicillium expansum Link using agricultural wastes (sunflower waste, cotton stalk and rice husk) as well as agro-industrial wastes (date syrup and molasses) as sources of carbon. Maximum production of invertase (7.03 U/mL) was observed when the strain was grown on culture medium (CM1) containing yeast extract as a source of nitrogen, date syrup as a source of carbon after 48 h of incubation at initial pH 5.0, temperature 35 degree C, inoculum size of 6x106 conidia in 50 mL of culture medium and agitation rate of 150 rev/min. After optimization the enzyme was also purified partially and then characterized. Kinetic constants (Km 2.57 mM and Vmax 178.6 U/mL/min) were determined by Lineweaver-Burk Plot and molecular mass (110 kDa) by 10% SDS-PAGE. Invertase showed maximum activity at pH 5.5 (128.7 U/mL) and at the temperature of 60 degree C (114.6 U/mL). BaCl/sub 2/ (21.9%), MgSO/sub 4/ (42.6%), MnCl/sub 2/ (46.8%) and EDTA (8.3%) enhanced the relative activity of enzyme while HgCl2 (-90.9%), CuSO/sub 4/ (-82.3%) and CuCl/sub 2/ (-78.7%) were proved inhibitors. (author)

Mercury nonstoichiometry of the Hg1-xBa2CuO4+δ superconductor and the P(Hg)-P(O2)-T phase diagram of the Hg-Ba-Cu-O system

International Nuclear Information System (INIS)

Alyoshin, V.A.; Mikhailova, D.A.; Rudnyi, E.B.; Antipov, E.V.

2002-01-01

The P(Hg)-P(O 2 )-T phase diagram of the Hg-Ba-Cu-O system for the Ba:Cu=2:1 ratio was experimentally studied and followed by means of the thermodynamic modeling. It was shown that the Hg 1-x Ba 2 CuO 4+δ (Hg-1201) superconductor possesses a significant range of Hg-nonstoichiometry and exists in a certain P(Hg), P(O 2 ) and T range. Mercury nonstoichiometry of Hg-1201 was investigated in the 923≤T≤1095 K; 2.0≤P(Hg)≤8.4 atm; 0.09≤P(O 2 )≤0.86 atm ranges. It was found that the mercury content varies in the range of 0.80-0.94 under these conditions. The Gibbs energy of the Hg-1201 phase was estimated as a function of temperature and mercury concentration. The obtained results allow optimizing the synthesis conditions of Hg-1201 with a given Hg-content including preparation of the Hg-stoichiometric phase

The theory and art of corneal cross-linking.

Science.gov (United States)

McQuaid, Rebecca; Cummings, Arthur B; Mrochen, Michael

2013-08-01

Before the discovery of corneal cross-linking (CXL), patients with keratoconus would have had to undergo corneal transplantation, or wear rigid gas permeable lenses (RGPs) that would temporarily flatten the cone, thereby improving the vision. The RGP contact lens (CL) would not however alter the corneal stability and if the keratoconus was progressive, the continued steepening of the cone would occur under the RGP CL. To date, the Siena Eye has been the largest study to investigate long term effects of standard CXL. Three hundred and sixty-three eyes were treated and monitored over 4 years, producing reliable long-term results proving long-term stability of the cornea by halting the progression of keratoconus, and proving the safety of the procedure. Traditionally, CXL requires epithelial removal prior to corneal soakage of a dextran-based 0.1% riboflavin solution, followed by exposure of ultraviolet-A (UV-A) light for 30 min with an intensity of 3 mW/cm2. A series of in vitro investigations on human and porcine corneas examined the best treatment parameters for standard CXL, such as riboflavin concentration, intensity, wavelength of UV-A light, and duration of treatment. Photochemically, CXL is achieved by the generation of chemical bonds within the corneal stroma through localized photopolymerization, strengthening the cornea whilst minimizing exposure to the surrounding structures of the eye. In vitro studies have shown that CXL has an effect on the biomechanical properties of the cornea, with an increased corneal rigidity of approximately 70%. This is a result of the creation of new chemical bonds within the stroma.

Investigation of Hg uptake and transport between paddy soil and rice seeds combining Hg isotopic composition and speciation

OpenAIRE

C. Feng; Z. Pedrero; P. Li; B. Du; X. Feng; M. Monperrus; E. Tessier; S. Berail; D. Amouroux

2016-01-01

Abstract Human consumption of rice constitutes a potential toxicological risk in mercury (Hg) polluted areas such as Hg mining regions in China. It is recognized to be an important source of Hg for the local human diet considering the efficient bioaccumulation of methylmercury (MeHg) in rice seed. To assess Hg sources and uptake pathways to the rice plants, Hg speciation and isotopic composition were investigated in rice seeds and their corresponding paddy soils from different locations withi...

Collective structures in 185Hg

International Nuclear Information System (INIS)

Bourgeois, C.; Hildingsson, L.; Perrin, N.; Sergolle, H.; Hannachi, F.; Bastin, G.; Porquet, M.G.; Thibaud, J.P.; Beck, F.A.; Merdinger, J.C.

1988-01-01

Excited states of 185 Hg have been investigated via the 161 Dy ( 28 Si, 4n) reaction at 145 MeV. In-beam gamma-ray spectroscopy studies have been performed with the ''Chateau de Cristal'' 4π-multidetector array. Level scheme of 185 Hg has been established. Shape coexistence, still present in 185 Hg like in the neighbouring Hg isotopes, manifests itself through a weakly populated decoupled band built on the 13/2+ isomer and three strongly-coupled bands built on the prolate 1/2-[521], 7/2-[514], and 9/2+[624] Nilsson states

The subtle balance of weak supramolecular interactions: The hierarchy of halogen and hydrogen bonds in haloanilinium and halopyridinium salts

Directory of Open Access Journals (Sweden)

Kari Raatikainen

2010-01-01

Full Text Available The series of haloanilinium and halopyridinium salts: 4-IPhNH3Cl (1, 4-IPhNH3Br (5, 4-IPhNH3H2PO4 (6, 4-ClPhNH3H2PO4 (8, 3-IPyBnCl (9, 3-IPyHCl (10 and 3-IPyH-5NIPA (3-iodopyridinium 5-nitroisophthalate, 13, where hydrogen or/and halogen bonding represents the most relevant non-covalent interactions, has been prepared and characterized by single crystal X-ray diffraction. This series was further complemented by extracting some relevant crystal structures: 4-BrPhNH3Cl (2, CCDC ref. code TAWRAL, 4-ClPhNH3Cl (3, CURGOL, 4-FPhNH3Cl (4, ANLCLA, 4-BrPhNH3H2PO4, (7, UGISEI, 3-BrPyHCl, (11, CIHBAX and 3-ClPyHCl, (12, VOQMUJ from Cambridge Structural Database for sake of comparison. Based on the X-ray data it was possible to highlight the balance between non-covalent forces acting in these systems, where the relative strength of the halogen bonding C–X···A− (X = I, Br or Cl and the ratio between the halogen and hydrogen bonds [C–X···A− : D–H···A−] varied across the series.

Immobilization of LiCl-Li 2 O pyroprocessing salt wastes in chlorosodalite using glass-bonded hydrothermal and salt-occlusion methods

Energy Technology Data Exchange (ETDEWEB)

Riley, Brian J.; Peterson, Jacob A.; Kroll, Jared O.; Frank, Steven M.

2018-04-01

In this study, salt occlusion and hydrothermal processes were used to make chlorosodalite through reaction with a high-LiCl salt simulating a waste stream following pyrochemical treatment of oxide-based used nuclear fuel. Some products were reacted with glass binders to increase chlorosodalite yield through alkali ion exchange and aide in densification. Hydrothermal processes included reaction of the salt simulant in an acid digestion vessel with either zeolite 4A or sodium aluminate and colloidal silica. Chlorosodalite yields in the crystalline products were nearly complete in the glass-bonded materials at values of 100 mass% for the salt-occlusion method, up to 99.0 mass% for the hydrothermal synthesis with zeolite 4A, and up to 96 mass% for the hydrothermal synthesis with sodium aluminate and colloidal silica. These results show promise for using chemically stable chlorosodalite to immobilize oxide reduction salt wastes.

Immobilization of LiCl-Li2O pyroprocessing salt wastes in chlorosodalite using glass-bonded hydrothermal and salt-occlusion methods

Science.gov (United States)

Riley, Brian J.; Peterson, Jacob A.; Kroll, Jared O.; Frank, Steven M.

2018-04-01

In this study, hydrothermal and salt-occlusion processes were used to make chlorosodalite through reactions with a high-LiCl salt simulating a waste stream generated from pyrochemical treatment of oxide-based used nuclear fuel. Some products were reacted with glass binders to increase chlorosodalite yield through alkali ion exchange and to aid in densification. Hydrothermal processes included reaction of the salt simulant in an autoclave with either zeolite 4A or sodium aluminate and colloidal silica. Chlorosodalite yields in the crystalline products were nearly complete in the glass-bonded materials at values of 100 mass% for the salt-occlusion method, up to 99.0 mass% for the hydrothermal synthesis with zeolite 4A, and up to 96 mass% for the hydrothermal synthesis with sodium aluminate and colloidal silica. These results show promise for using chemically stable chlorosodalite to immobilize oxide reduction salt wastes.

Nature of the bonding in the AuNgX (Ng = Ar, Kr, Xe; X = F, Cl, Br, I) molecules. Topological study on electron density and the electron localization function (ELF).

Science.gov (United States)

Makarewicz, Emilia; Gordon, Agnieszka J; Berski, Slawomir

2015-03-19

Topological analysis of the electron localization function (ELF) has been carried out for the AuNgX (Ng = Ar, Kr, Xe; X = F, Cl, Br, I) molecules using the wave function approximated by the CCSD, MP2, and DFT(B3LYP, M062X) methods including zero-order regular approximation (ZORA). In the Ng-F bond, the bonding disynaptic attractor V(Ng,F) is missing; therefore, there are no signs of the covalent binding. The nature of the Au-Ng bond depends on the computational method used. Analysis of the ELF carried out for the AuArF and AuXeF molecules, with the wave function approximated by the CCSD and MP2 methods, shows the V(Au,Ng) attractor possibly corresponding to a partially covalent binding between the gold and noble gas atom. However, its very small basin population (<1e) and a very large value of the variance of the basin population suggest that the Au-Ng bond has a very delocalized character. Such bond nature may be related to the charge shift concept with a resonance of the Au(-+)NgX, Au(+-)NgX hybrids. The weakest Au-Ng bond, in terms of the smallest amount of electron density for the V(Au,Ng) basin, is found for the AuKrF molecule with the CCSD method (0.13e). The MP2 method, however, does not yield any V(Au, Ng) population; hence, the covalent Au-Kr bond is not confirmed. Because the V(Au,Ng) attractor is also not observed with the DFT method, the proper characterization of the Au-Ng bond requires proper description of correlation effects. Additional studies on the Au2 and [AuXe](+) molecules, performed at the CCSD and B3LYP levels, exhibit no V(Au,Au) and V(Au,Xe) bonding basins either.

2,2,2-Trichloro-N-(3,4-dimethylphenylacetamide

Directory of Open Access Journals (Sweden)

Hartmut Fuess

2009-05-01

Full Text Available The conformation of the N—H bond in the title compound, C10H10Cl3NO, is anti to the C=O bond. The amide H atom exhibits both intramolecular N—H...Cl and intermolecular N—H...O hydrogen bonding. The latter interactions link the molecules into infinite chains.

Determination of subnanomolar levels of mercury (II) by using a graphite paste electrode modified with MWCNTs and Hg(II)-imprinted polymer nanoparticles.

Science.gov (United States)

Alizadeh, Taher; Hamidi, Negin; Ganjali, Mohamad Reza; Rafiei, Faride

2017-12-05

Mercury ion-imprinted polymer nanoparticles (Hg-IP-NPs) were synthesized via precipitation polymerization by using itaconic acid as a functional monomer. A carbon paste electrode was impregnated with the synthesized Hg-IP-NPs and MWCNTs to obtain a highly sensitive and selective electrode for determination of Hg(II). Mercury ion is first accumulated on the electrode surface via an open circuit procedure. After reduction of Hg(II) ions to its metallic form at a negative pre-potential, square wave anodic stripping voltammetry was applied to generate the electrochemical signal. The high affinity of the Hg-IP-NPs for Hg(II) was substantiated by comparing of the signals of electrodes with imprinted and non-imprinted polymer. The beneficial effect of MWCNTs on the voltammetric signal is also demonstrated. Under the optimized conditions and at a typical working potential of +0.05 V (vs. Ag/AgCl), the electrode has a linear response in the 0.1-20 nmol L -1 Hg(II) concentration range and a 29 pM detection limit. The electrochemical sensitivity is as high as 1441 A·M -1 ·cm -2 which is among the best values known. The electrode was applied to the determination of Hg(II) in water samples. Graphical abstract Schematic representation of the sensor electrode modified with mercury-imprinted polymer nanoparticles, and the recognition and voltammetric determination steps.

Supercooling of aqueous NaCl and KCl solutions under acoustic levitation.

Science.gov (United States)

Lü, Y J; Wei, B

2006-10-14

The supercooling capability of aqueous NaCl and KCl solutions is investigated at containerless state by using acoustic levitation method. The supercooling of water is obviously enhanced by the alkali metal ions and increases linearly with the augmentation of concentrations. Furthermore, the supercooling depends on the nature of ions and is 2-3 K larger for NaCl solution than that for KCl solution in the present concentration range: Molecular dynamics simulations are performed to reveal the intrinsic correlation between supercoolability and microstructure. The translational and orientational order parameters are applied to quantitatively demonstrate the effect of ionic concentration on the hydrogen-bond network and ice melting point. The disrupted hydrogen-bond structure determines essentially the concentration dependence of supercooling. On the other hand, the introduced acoustic pressure suppresses the increase of supercooling by promoting the growth and coalescence of microbubbles, the effective nucleation catalysts, in water. However, the dissolved ions can weaken this effect, and moreover the degree varies with the ion type. This results in the different supercoolability for NaCl and KCl solutions under the acoustic levitation conditions.

Effect of cation nature of Cl2- yields in pulse radiolysis of alkali metal chloride aqueous solutions

International Nuclear Information System (INIS)

Kabakchi, S.A.; Zansokhova, A.A.; Pikaev, A.K.

1975-01-01

A study is made of the amount of Cl 2 - formed during a pulsating radiolysis of potassium, rubidium and cesium chlorides in aqueous solutions saturated with air. An equation is presented relating the yield of Cl 2 - and the concentration of the starting materials. Various mechanisms describing the radiolysis of neutral aqueous solutions of the chlorides are proposed. The observed effect of the cation on the efficiency of Cl 2 - formations favours the mechanism according to which Cl 2 - forms through the reaction of Cl - ion with a ''hole''. Due to charge migration in the conductivity zone the electron transfer reaction either goes steadily by jumps. As a result of the interaction between the ''hole'' and water [H 3 O + ...OH] a complex is formed from a hydrogen ion and OH radical, which are united trhough the hydrogen bond. Disturbance of the hydrogen bond structure should increase the probability of disintegration of the complex

EVALUATION OF CEMENT-BONDED PARTICLE BOARD PRODUCED FROM AFZELIA AFRICANA WOOD RESIDUES

Directory of Open Access Journals (Sweden)

OLUFEMI A. SOTANNDE

2012-12-01

Full Text Available The study was design to evaluate the physical and mechanical properties of cement-bonded particleboards produced from Afzelia africana wood residues. The production variables investigated were three wood particle types (flakes, flake-sawdust mix and sawdust, three chemical accelerators (CaCl2, MgCl2 and AlCl3 and four wood-cement ratios (1:2.0, 1:2.5, 1:3.0 and 1:3.5. The accelerators were based on 2% by weight of cement used. The boards produced were subjected to physical tests such as density, percentage water absorption and thickness swelling. Mechanical properties evaluated were modulus of rupture, internal bonding strength and compressive strength. The results revealed that the type of particle used, wood-cement ratio and chemical additives had a marked influence on the physical and mechanical properties of the boards (p < 0.05. From quality view point, flake-sawdust composite ranked best while flake boards ranked least. Similarly, CaCl2 had the best influence on the setting of the boards followed by MgCl2 and AlCl3. Finally, it has been shown that particle boards that satisfied the BISON type HZ requirement and ISO 8335 can be produced from Afzelia africana particularly at wood-cement of 1:2.5 and above.

46 CFR 53.05-1 - Safety valve requirements for steam boilers (modifies HG-400 and HG-401).

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Safety valve requirements for steam boilers (modifies HG-400 and HG-401). 53.05-1 Section 53.05-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... requirements for steam boilers (modifies HG-400 and HG-401). (a) The pressure relief valve requirements and the...

Use of new threshold detector 199Hg(n,n')/sup 199m/Hg for neutron spectrum unfolding

International Nuclear Information System (INIS)

Sakurai, K.

1982-01-01

The nuclear data for the 199 Hg(n,n')/sup 199m/Hg reaction are reviewed and the data are used for neutron spectrum unfolding. The neutron spectrum of the YAYOI glory-hole is unfolded by SAND II with 10 nuclear reactions including the 199 Hg(n,n')/sup 199m/Hg reaction. The ratio of the measured reaction rate to the calculated reaction rate is about 1:1.1 for the guess spectrum. The 199 Hg(n,n')/sup 199m/Hg, 115 In(n,n')/sup 115m/In, 103 Rh(n,n')/sup 103m/Rh reactions should be useful threshold detectors for the neutron dosimetry with low level fast neutron flux

The application of ¹⁹⁹Hg NMR and ^199mHg perturbed angular correlation (PAC) spectroscopy to define the biological chemistry of Hg^II

DEFF Research Database (Denmark)

Iranzo, Olga; Thulstrup, Peter Waaben; Ryu, Seung-baek

2007-01-01

The use of de novo designed peptides is a powerful strategy to elucidate HgII-protein interactions and to gain insight into the chemistry of HgII in biological systems. Cysteine derivatives of the designed -helical peptides of the TRI family [Ac-G-(LaKbAcLdEeEfKg)4-G-NH2] bind HgII at high p...... to characterize the distinct species that are generated under different pH conditions and peptide TRI L9C/HgII ratios. These studies prove for the first time the formation of [Hg{(TRI L9C)2-(TRI L9C H)}], a dithiolate-HgII complex in the hydrophobic interior of the three-stranded coiled coil (TRI L9C)3. 199Hg NMR...

Long-term Hg pollution induced Hg tolerance in the terrestrial isopod Porcellio scaber (Isopoda, Crustacea)

International Nuclear Information System (INIS)

Lapanje, A.; Drobne, D.; Nolde, N.; Valant, J.; Muscet, B.; Leser, V.; Rupnik, M.

2008-01-01

The aim of our work was to assess the pollution-induced community tolerance (PICT) of isopod gut microbiota and pollution-induced isopod population tolerance (PIPT). Animals collected from a chronically Hg polluted and an unpolluted location were exposed for 14 days to 10 μg Hg/g dry food under laboratory conditions. The lysosomal membrane stability, hepatopancreas epithelium thickness, feeding activity and animal bacterial gut microbiota composition were determined. The results confirm the hypothesis that the response to short-term Hg exposure differs for animals from the Hg polluted and the unpolluted field locations. The animals and their gut microbiota from the Hg polluted location were less affected by Hg in a short-term feeding experiment than those from the unpolluted environment. We discuss the pollution-induced population tolerance of isopods and their gut microbiota as a measure of effects of long-term environmental pollution. The ecological consequences of such phenomena are also discussed. - Isopods (Porcellio scaber) as well as their bacterial gut community from a mercury-polluted site are mercury tolerant

Long-term Hg pollution induced Hg tolerance in the terrestrial isopod Porcellio scaber (Isopoda, Crustacea)

Energy Technology Data Exchange (ETDEWEB)

Lapanje, A. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Institute of Physical Biology, Veliko Mlacevo 59, 1290 Grosuplje (Slovenia)], E-mail: ales.lapanje@bf.uni-lj.si; Drobne, D. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Nolde, N. [Institute Jozef Stefan, Department of Environmental Sciences, Jamova 39, 1000 Ljubljana (Slovenia); Valant, J. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Muscet, B. [Institute of Physical Biology, Veliko Mlacevo 59, 1290 Grosuplje (Slovenia); Leser, V. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Rupnik, M. [Institute of Public Health, Prvomajska 1, 2000 Maribor (Slovenia); Faculty of Medicine, University of Maribor, Slomskov trg 15, 2000 Maribor (Slovenia)

2008-06-15

The aim of our work was to assess the pollution-induced community tolerance (PICT) of isopod gut microbiota and pollution-induced isopod population tolerance (PIPT). Animals collected from a chronically Hg polluted and an unpolluted location were exposed for 14 days to 10 {mu}g Hg/g dry food under laboratory conditions. The lysosomal membrane stability, hepatopancreas epithelium thickness, feeding activity and animal bacterial gut microbiota composition were determined. The results confirm the hypothesis that the response to short-term Hg exposure differs for animals from the Hg polluted and the unpolluted field locations. The animals and their gut microbiota from the Hg polluted location were less affected by Hg in a short-term feeding experiment than those from the unpolluted environment. We discuss the pollution-induced population tolerance of isopods and their gut microbiota as a measure of effects of long-term environmental pollution. The ecological consequences of such phenomena are also discussed. - Isopods (Porcellio scaber) as well as their bacterial gut community from a mercury-polluted site are mercury tolerant.

Two Zn and Hg bromide salts based on 1-ethyl-3-methyl imidazolium ionic liquid: Ionothermal synthesis, structures and supramolecular organization

Directory of Open Access Journals (Sweden)

Xiu-Cheng Zhang

2012-12-01

Full Text Available Two Zn(II and Hg(II bromide salts, [EMI]2[ZnBr4] (1 and [EMI][HgBr3] (2, have been synthesized under ionothermal conditions using 1-ethyl-3-methyl imidazolium bromide ([EMI]Br as solvents. 1 consists of tetrahedral anion [ZnBr4]2− and 2 consists of 1D double chain locating in the cavities surrounded by [EMI]+ cations. Both compounds exhibit 3D supramolecular architectures organized by the C-H•••Br hydrogen bondings and alkyl-alkyl interactions.DOI: http://dx.doi.org/10.4314/bcse.v26i3.9

Proton transfer in a short hydrogen bond caused by solvation shell fluctuations: an ab initio MD and NMR/UV study of an (OHO)(-) bonded system.

Science.gov (United States)

Pylaeva, Svetlana; Allolio, Christoph; Koeppe, Benjamin; Denisov, Gleb S; Limbach, Hans-Heinrich; Sebastiani, Daniel; Tolstoy, Peter M

2015-02-14

We present a joint experimental and quantum chemical study on the influence of solvent dynamics on the protonation equilibrium in a strongly hydrogen bonded phenol-acetate complex in CD2Cl2. Particular attention is given to the correlation of the proton position distribution with the internal conformation of the complex itself and with fluctuations of the aprotic solvent. Specifically, we have focused on a complex formed by 4-nitrophenol and tetraalkylammonium-acetate in CD2Cl2. Experimentally we have used combined low-temperature (1)H and (13)C NMR and UV-vis spectroscopy and showed that a very strong OHO hydrogen bond is formed with proton tautomerism (PhOH···(-)OAc and PhO(-)···HOAc forms, both strongly hydrogen bonded). Computationally, we have employed ab initio molecular dynamics (70 and 71 solvent molecules, with and without the presence of a counter-cation, respectively). We demonstrate that the relative motion of the counter-cation and the "free" carbonyl group of the acid plays the major role in the OHO bond geometry and causes proton "jumps", i.e. interconversion of PhOH···(-)OAc and PhO(-)···HOAc tautomers. Weak H-bonds between CH(CD) groups of the solvent and the oxygen atom of carbonyl stabilize the PhOH···(-)OAc type of structures. Breaking of CH···O bonds shifts the equilibrium towards PhO(-)···HOAc form.

HgTe based topological insulators

International Nuclear Information System (INIS)

Bruene, Christoph

2014-01-01

This PhD thesis summarizes the discovery of topological insulators and highlights the developments on their experimental observations. The work focuses on HgTe. The thesis is structured as follows: - The first chapter of this thesis will give a brief overview on discoveries in the field of topological insulators. It focuses on works relevant to experimental results presented in the following chapters. This includes a short outline of the early predictions and a summary of important results concerning 2-dimensional topological insulators while the final section discusses observations concerning 3-dimensional topological insulators. - The discovery of the quantum spin Hall effect in HgTe marked the first experimental observation of a topological insulator. Chapter 2 focuses on HgTe quantum wells and the quantum spin Hall effect. The growth of high quality HgTe quantum wells was one of the major goals for this work. In a final set of experiments the spin polarization of the edge channels was investigated. Here, we could make use of the advantage that HgTe quantum well structures exhibit a large Rashba spin orbit splitting. - HgTe as a 3-dimensional topological insulator is presented in chapter 3. - Chapters 4-6 serve as in depth overviews of selected works: Chapter 4 presents a detailed overview on the all electrical detection of the spin Hall effect in HgTe quantum wells. The detection of the spin polarization of the quantum spin Hall effect is shown in chapter 5 and chapter 6 gives a detailed overview on the quantum Hall effect originating from the topological surface state in strained bulk HgTe.

Metal-ligand delocalization and spin density in the CuCl2 and [CuCl4](2-) molecules: Some insights from wave function theory.

Science.gov (United States)

Giner, Emmanuel; Angeli, Celestino

2015-09-28

The aim of this paper is to unravel the physical phenomena involved in the calculation of the spin density of the CuCl2 and [CuCl4](2-) systems using wave function methods. Various types of wave functions are used here, both variational and perturbative, to analyse the effects impacting the spin density. It is found that the spin density on the chlorine ligands strongly depends on the mixing between two types of valence bond structures. It is demonstrated that the main difficulties found in most of the previous studies based on wave function methods come from the fact that each valence bond structure requires a different set of molecular orbitals and that using a unique set of molecular orbitals in a variational procedure leads to the removal of one of them from the wave function. Starting from these results, a method to compute the spin density at a reasonable computational cost is proposed.

[μ-1,1′-(Butane-1,4-diyldi-1H-benzimidazole-κ2N3:N3′]bis{[N,N′-bis(carboxymethylethylenediamine-N,N′-diacetato-κ5O,O′,O′′,N,N′]mercury(II} methanol disolvate

Directory of Open Access Journals (Sweden)

Gang-Sen Li

2009-08-01

Full Text Available The binuclear title complex, [Hg2(C10H14N2O82(C18H18N4]·2CH3OH, lies on an inversion center with the unique HgII ion coordinated in a disorted octahedral environment with one Hg—N bond significantly shorter than the other two. In the crystal structure, intermolecular O—H...O hydrogen bonds link complex and solvent molecules into a three-dimensional network.

Crystal structure of difluorochloronium hexafluoroniobate and hexafluorotantalate, ClF2NbF6 and ClF2TaF6

International Nuclear Information System (INIS)

Ehllern, A.M.; Antipin, M.Yu.; Sharabarin, A.V.; Struchkov, Yu.T.

1991-01-01

Crystal structure of ClF 2 NbF 6 (1) and ClF 2 TaF 6 (2) were investigated by the method of X-ray diffraction analysis. Salts 1 and 2 are isostructural, crystals are rhombic: a = 9.981(2) and 10.049(2), b = 5.781(1) and 5.775(1), c = 10.552(2) and 10.670(2) A, V = 608.9(3) and 619.2(3) A 3 , Z = 4, d calcd 3.058 and 3.952 g/cm 3 , sp. gr. Pcca. Both salts are characterized by ionic structure. Bond lengths and valent angles, general view of 1 crystal structure are presented

Sudden change of quadrupole moment between the first 5/2- states of 197Hg and 199Hg

International Nuclear Information System (INIS)

Herzog, P.; Krien, K.; Freitag, M.; Reuschenbach, M.; Walitzki, H.

1980-01-01

Low-temperature time differential perturbed angular correlation experiments with the 164 KeV-134 keV cascade of sup(197m)Hg in a zinc matrix give evidence that the hitherto accepted value of the quadrupole moment of the first 5/2 - state of 197 Hg is erroneous. A new value is derived from a time differential perturbed angular correlation experiment with the 374 keV-158 keV cascade of sup(199m)Hg implanted into a Be single crystal and comparison with an analogous experiment for sup(197m)Hg. Taking Q(5/2 - , 199 Hg) = +0.95(7) b we derive Q(5/2 - , 197 Hg) = 0.081(6) b. This change of quadrupole moment is discussed in the framework of the shell model. (orig.)

Phase equilibria and thermodynamic functions for Ag–Hg and Cu–Hg binary systems

International Nuclear Information System (INIS)

Liu, Yajun; Wang, Guan; Wang, Jiang; Chen, Yang; Long, Zhaohui

2012-01-01

Highlights: ► The thermodynamic properties of Ag–Hg and Cu–Hg are explored in order to facilitate dental materials design. ► A self-consistent set of thermodynamic parameters is obtained. ► The experimental information can be well reproduced by the optimized thermodynamic data. - Abstract: In order to facilitate the computational design of new amalgams for novel dental alloys, the phase equilibria, phase diagrams and thermodynamic functions for Ag–Hg and Cu–Hg binary systems are explored in this work, based on the CALPHAD framework and experimental characterizations. The Gibbs free energies of the solution phases as well as the stoichiometric phases are calculated, with the aid of enthalpies of mixing, activities, enthalpies of formation, and phase equilibrium data. The thermodynamic descriptions provided in this work enable the stabilities of each phase at various temperatures and compositions to be well described, which contribute to the establishment of a general database to design novel metallic dental materials.

Phase equilibria and thermodynamic functions for Ag-Hg and Cu-Hg binary systems

Energy Technology Data Exchange (ETDEWEB)

Liu, Yajun, E-mail: yajunliu@gatech.edu [School of Materials and Energy, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wang, Guan [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wang, Jiang [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Chen, Yang [Mining, Metallurgy and Materials Research Department, General Research Institute for Nonferrous Metals, Beijing 100088 (China); Long, Zhaohui [School of Mechanical Engineering, Xiangtan University, Xiangtan, Hunan 411105 (China)

2012-11-10

Highlights: Black-Right-Pointing-Pointer The thermodynamic properties of Ag-Hg and Cu-Hg are explored in order to facilitate dental materials design. Black-Right-Pointing-Pointer A self-consistent set of thermodynamic parameters is obtained. Black-Right-Pointing-Pointer The experimental information can be well reproduced by the optimized thermodynamic data. - Abstract: In order to facilitate the computational design of new amalgams for novel dental alloys, the phase equilibria, phase diagrams and thermodynamic functions for Ag-Hg and Cu-Hg binary systems are explored in this work, based on the CALPHAD framework and experimental characterizations. The Gibbs free energies of the solution phases as well as the stoichiometric phases are calculated, with the aid of enthalpies of mixing, activities, enthalpies of formation, and phase equilibrium data. The thermodynamic descriptions provided in this work enable the stabilities of each phase at various temperatures and compositions to be well described, which contribute to the establishment of a general database to design novel metallic dental materials.

A study of capillary discharge lamps in Ar-Hg and Xe-Hg mixtures

International Nuclear Information System (INIS)

Denisova, N; Gavare, Z; Revalde, G; Skudra, Ja; Veilande, R

2011-01-01

Low-pressure capillary discharge lamps in Ar-Hg and Xe-Hg mixtures are studied. The discharge size is 0.5 mm (500 μm) in radius. According to the literature, such types of plasma sources are classified as microplasmas. The studies include spectrally resolved optical measurements, tomographic reconstructions and numerical simulations using the collisional-radiative model for an Ar-Hg plasma. We discuss the problems of theoretical modelling and experimental diagnostics of microplasma sources. It is shown that the conventional collisional-radiative model, based on the assumption that transportation of atoms in the highly excited states can be neglected, has limitations in modelling a capillary discharge in an Ar-Hg mixture. It is found that diffusion of highly excited mercury atoms to the wall influences the emission properties of the capillary discharge. We have concluded that applications of the emission tomography method to microplasmas require a special analysis in each particular case.

Evidence for phosphorus bonding in phosphorus trichloride-methanol adduct: a matrix isolation infrared and ab initio computational study.

Science.gov (United States)

Joshi, Prasad Ramesh; Ramanathan, N; Sundararajan, K; Sankaran, K

2015-04-09

The weak interaction between PCl3 and CH3OH was investigated using matrix isolation infrared spectroscopy and ab initio computations. In a nitrogen matrix at low temperature, the noncovalent adduct was generated and characterized using Fourier transform infrared spectroscopy. Computations were performed at B3LYP/6-311++G(d,p), B3LYP/aug-cc-pVDZ, and MP2/6-311++G(d,p) levels of theory to optimize the possible geometries of PCl3-CH3OH adducts. Computations revealed two minima on the potential energy surface, of which, the global minimum is stabilized by a noncovalent P···O interaction, known as a pnictogen bonding (phosphorus bonding or P-bonding). The local minimum corresponded to a cyclic adduct, stabilized by the conventional hydrogen bonding (Cl···H-O and Cl···H-C interactions). Experimentally, 1:1 P-bonded PCl3-CH3OH adduct in nitrogen matrix was identified, where shifts in the P-Cl modes of PCl3, O-C, and O-H modes of CH3OH submolecules were observed. The observed vibrational frequencies of the P-bonded adduct in a nitrogen matrix agreed well with the computed frequencies. Furthermore, computations also predicted that the P-bonded adduct is stronger than H-bonded adduct by ∼1.56 kcal/mol. Atoms in molecules and natural bond orbital analyses were performed to understand the nature of interactions and effect of charge transfer interaction on the stability of the adducts.

Evidence for Interfacial Halogen Bonding.

Science.gov (United States)

Swords, Wesley B; Simon, Sarah J C; Parlane, Fraser G L; Dean, Rebecca K; Kellett, Cameron W; Hu, Ke; Meyer, Gerald J; Berlinguette, Curtis P

2016-05-10

A homologous series of donor-π-acceptor dyes was synthesized, differing only in the identity of the halogen substituents about the triphenylamine (TPA; donor) portion of each molecule. Each Dye-X (X=F, Cl, Br, and I) was immobilized on a TiO2 surface to investigate how the halogen substituents affect the reaction between the light-induced charge-separated state, TiO2 (e(-) )/Dye-X(+) , with iodide in solution. Transient absorption spectroscopy showed progressively faster reactivity towards nucleophilic iodide with more polarizable halogen substituents: Dye-F < Dye-Cl < Dye-Br < Dye-I. Given that all other structural and electronic properties for the series are held at parity, with the exception of an increasingly larger electropositive σ-hole on the heavier halogens, the differences in dye regeneration kinetics for Dye-Cl, Dye-Br, and Dye-I are ascribed to the extent of halogen bonding with the nucleophilic solution species. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crystal structure of 4,6-diamino-2,2-dimethyl-3-[3-(2,4,5-trichlorophenoxypropoxy]-2,3-dihydro-1,3,5-triazin-1-ium chloride methanol monosolvate

Directory of Open Access Journals (Sweden)

Pattarapol Khongsuk

2015-08-01

Full Text Available In the title methanol-solvated salt, C14H19Cl3N5O2+·Cl−·CH3OH, the triazine molecule is protonated at one of the triazine N atoms. In the crystal, the triazine cations are linked through a pair of N—H...N hydrogen bonds, with graph-set R22(8, forming an inversion dimer. The protonated N atom and the 2- and 4-amino groups of the triazine cation interact with the chloride anion through N—H...Cl hydrogen bonds, leading to the formation of a tape structure running along the b-axis direction. A short Cl...Cl contact [3.2937 (9 Å] is observed in the tape. The methanol molecule is linked to the chloride anion and the triazine cation, respectively, by an O—H...Cl hydrogen bond and a C—H...O interaction.

Tetraammineplatinum(II) aquapentachloroiridate(III) dihydrate, [Pt(NH3)4][IrCl5(H2O)

International Nuclear Information System (INIS)

Garnier, E.; Bele, M.

1994-01-01

The crystal is built up from planar Pt(NH 3 ) 4 2+ cations, octahedral IrCl 5 (H 2 O) 2- anions and two H 2 O molecules. The coordination of these ions is 6/6, thus leading to a NaCl crystal structure. Electrostatic interactions and N..Cl, N..O and N..N short contacts (possible hydrogen bonds) take part in the packing of the structure and form a three-dimensional network. (orig.)

Isotopic Hg in an Allende carbon-rich residue

Science.gov (United States)

Reed, G. W., Jr.; Jovanovic, S.

1990-01-01

A carbon-rich residue from Allende subjected to stepwise heating yielded two isotopically resolvable types of Hg: one with an (Hg-196)/(Hg-202) concentration ratio the same as terrestrial (monitor) Hg; the other enriched in Hg-196 relative to Hg-202 by about 60 percent. Hg with the 202 isotope enriched relative to 196, as is found in bulk Allende, was not observed. Whether the result of mass fractionation or nucleosynthesis, the distinct types of Hg entered different carrier phases and were not thermally mobilized since the accretion of the Allende parent body.

UV photolysis of 4-iodo-, 4-bromo-, and 4-chlorophenol: Competition between C-Y (Y = halogen) and O-H bond fission

Science.gov (United States)

Sage, Alan G.; Oliver, Thomas A. A.; King, Graeme A.; Murdock, Daniel; Harvey, Jeremy N.; Ashfold, Michael N. R.

2013-04-01

The wavelength dependences of C-Y and O-H bond fission following ultraviolet photoexcitation of 4-halophenols (4-YPhOH) have been investigated using a combination of velocity map imaging, H Rydberg atom photofragment translational spectroscopy, and high level spin-orbit resolved electronic structure calculations, revealing a systematic evolution in fragmentation behaviour across the series Y = I, Br, Cl (and F). All undergo O-H bond fission following excitation at wavelengths λ ≲ 240 nm, on repulsive ((n/π)σ*) potential energy surfaces (PESs), yielding fast H atoms with mean kinetic energies ˜11 000 cm-1. For Y = I and Br, this process occurs in competition with prompt C-I and C-Br bond cleavage on another (n/π)σ* PES, but no Cl/Cl* products unambiguously attributable to one photon induced C-Cl bond fission are observed from 4-ClPhOH. Differences in fragmentation behaviour at longer excitation wavelengths are more marked. Prompt C-I bond fission is observed following excitation of 4-IPhOH at all λ ≤ 330 nm; the wavelength dependent trends in I/I* product branching ratio, kinetic energy release, and recoil anisotropy suggest that (with regard to C-I bond fission) 4-IPhOH behaves like a mildly perturbed iodobenzene. Br atoms are observed when exciting 4-BrPhOH at long wavelengths also, but their velocity distributions suggest that dissociation occurs after internal conversion to the ground state. O-H bond fission, by tunnelling (as in phenol), is observed only in the cases of 4-FPhOH and, more weakly, 4-ClPhOH. These observed differences in behaviour can be understood given due recognition of (i) the differences in the vertical excitation energies of the C-Y centred (n/π)σ* potentials across the series Y = I increased spin-orbit coupling in, particularly, 4-IPhOH. The present results provide (another) reminder of the risks inherent in extrapolating photochemical behaviour measured for one molecule at one wavelength to other (related) molecules and to

Gasometría arterial en adultos clínicamente sanos a 3350 metros de altitud

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César J Pereira-Victorio

Full Text Available Objetivo. Determinar los valores gasométricos arteriales de normalidad, en adultos clínicamente sanos que viven a 3350 metros de altitud. Materiales y métodos. Estudio realizado en Cusco, distrito de Santiago a 3350 m de altitud, se determinó una muestra de 118 sujetos mediante un estudio piloto previo, seleccionados por muestreo por conveniencia; las personas tenían entre 20-59 años de edad, sin antecedentes patológicos pulmonares, cardiovasculares o hematológicos, con práctica deportiva menor a 60 min/día, sin hábito tabáquico, residentes los 5 años previos al estudio en Cusco y catalogados como "clínicamente sanos" por dos médicos internistas y un neumólogo. La recolección gasométrica fue estandarizada, para el análisis estadístico se empleó medidas de tendencia central y dispersión, t de Student y análisis de varianza, correlación lineal y regresión lineal múltiple. Resultados. Las mujeres conformaron el 57,6% de la muestra; la frecuencia respiratoria fue 16,2 por minuto, y el IMC 24,8. Los resultados gasométricos fueron: pH=7,42mEq/L; pO =61,08mmHg; pCO =30,62mmHg; pAO =62,52mmHg; SO =91,13%; AaDO =0,0mmHg; Hto 44,22%; Hb 14,74mg/ dL; CaO2 18,18 vols/%; HCO3 19,74mmol/L; pO2/FiO2 290,79 y Anion Gap 20,99. Mediante regresión lineal, a partir de los 20 años de edad, por cada año cumplido, "disminuyen" pO2 (0,122mmHg, pAO2 (0,08mmHg, SO2 (0,05%, índice pO2/FiO2 (0,571mmHg; e "incrementa" la pCO2 (0,056mmHg. Conclusiones. Los resultados hallados respecto a los parámetros gasométricos son diferentes a los del nivel de mar y pueden ser empleados en poblaciones que habitan a altitud semejante a la del estudio

An investigation of mercury sources in the Puyango-Tumbes River: Using stable Hg isotopes to characterize transboundary Hg pollution.

Science.gov (United States)

Schudel, Gary; Miserendino, Rebecca Adler; Veiga, Marcello M; Velasquez-López, P Colon; Lees, Peter S J; Winland-Gaetz, Sean; Davée Guimarães, Jean Remy; Bergquist, Bridget A

2018-07-01

Mercury (Hg) concentrations and stable isotopes along with other trace metals were examined in environmental samples from Ecuador and Peru's shared Puyango-Tumbes River in order to determine the extent to which artisanal- and small-scale gold mining (ASGM) in Portovelo-Zaruma, Ecuador contributes to Hg pollution in the downstream aquatic ecosystem. Prior studies investigated the relationship between ASGM activities and downstream Hg pollution relying primarily on Hg concentration data. In this study, Hg isotopes revealed an isotopically heavy Hg signature with negligible mass independent fractionation (MIF) in downstream sediments, which was consistent with the signature observed in the ASGM source endmember. This signature was traced as far as ∼120 km downstream of Portovelo-Zaruma, demonstrating that Hg stable isotopes can be used as a tool to fingerprint and trace sources of Hg over vast distances in freshwater environments. The success of Hg isotopes as a source tracer in fresh waters is largely due to the particle-reactive nature of Hg. Furthermore, the magnitude and extent of downstream Hg, lead, copper and zinc contamination coupled with the Hg isotopes suggest that it is unlikely that the smaller artisanal-scale activities, which do not use cyanidation, are responsible for the pollution. More likely it is the scale of ores processed and the cyanide leaching, which can release other metals and enhance Hg transport, used during small-scale gold mining that is responsible. Thus, although artisanal- and small-scale gold mining occur in tandem in Portovelo-Zaruma, a distinction should be made between these two activities. Copyright © 2018 Elsevier Ltd. All rights reserved.

The theory and art of corneal cross-linking

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Rebecca McQuaid

2013-01-01

Full Text Available Before the discovery of corneal cross-linking (CXL, patients with keratoconus would have had to undergo corneal transplantation, or wear rigid gas permeable lenses (RGPs that would temporarily flatten the cone, thereby improving the vision. The RGP contact lens (CL would not however alter the corneal stability and if the keratoconus was progressive, the continued steepening of the cone would occur under the RGP CL. To date, the Siena Eye has been the largest study to investigate long term effects of standard CXL. Three hundred and sixty-three eyes were treated and monitored over 4 years, producing reliable long-term results proving long-term stability of the cornea by halting the progression of keratoconus, and proving the safety of the procedure. Traditionally, CXL requires epithelial removal prior to corneal soakage of a dextran-based 0.1% riboflavin solution, followed by exposure of ultraviolet-A (UV-A light for 30 min with an intensity of 3 mW/cm2. A series of in vitro investigations on human and porcine corneas examined the best treatment parameters for standard CXL, such as riboflavin concentration, intensity, wavelength of UV-A light, and duration of treatment. Photochemically, CXL is achieved by the generation of chemical bonds within the corneal stroma through localized photopolymerization, strengthening the cornea whilst minimizing exposure to the surrounding structures of the eye. In vitro studies have shown that CXL has an effect on the biomechanical properties of the cornea, with an increased corneal rigidity of approximately 70%. This is a result of the creation of new chemical bonds within the stroma.

Bond markets in Africa

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Yibin Mu

2013-07-01

Full Text Available African bond markets have been steadily growing in recent years, but nonetheless remain undeveloped. African countries would benefit from greater access to financing and deeper financial markets. This paper compiles a unique set of data on government securities and corporate bond markets in Africa. It then applies an econometric model to analyze the key determinants of African government securities market and corporate bond market capitalization. Government securities market capitalization is directly related to better institutions and interest rate volatility, and inversely related to smaller fiscal deficits, higher interest rate spreads, exchange rate volatility, and current and capital account openness. Corporate bond market capitalization is directly linked to economic size, the level of development of the economy and financial markets, better institutions, and interest rate volatility, and inversely related to higher interest rate spreads and current account openness. Policy implications follow.

Natural Hg isotopic composition of different Hg compounds in mammal tissues as a proxy for in vivo breakdown of toxic methylmercury.

Science.gov (United States)

Perrot, Vincent; Masbou, Jeremy; Pastukhov, Mikhail V; Epov, Vladimir N; Point, David; Bérail, Sylvain; Becker, Paul R; Sonke, Jeroen E; Amouroux, David

2016-02-01

In the last decade, specific attention has been paid to total mercury (HgT) stable isotopic composition, especially in natural samples such as aquatic organisms, due to its potential to track the cycle of this toxic element in the environment. Here, we investigated Hg Compound Specific stable Isotopic Composition (CSIC) of natural inorganic Hg (iHg) and methylmercury (MMHg) in various tissues of aquatic mammals (Beluga whale from the Arctic marine environment and seals from the freshwater lake Baikal, Russia). In seals' organs the variation in mass dependent fractionation (MDF, δ(202)Hg) for total Hg was significantly correlated to the respective fraction of iHg and MMHg compounds, with MMHg being enriched by ∼ 3‰ in heavier isotopes relative to iHg. On the other hand, we observe insignificant variation in Hg mass independent isotope fractionation (MIF, Δ(199)Hg) among iHg and MMHg in all organs for the same mammal species and MMHg in prey items. MIF signatures suggest that both MMHg and iHg in aquatic mammals have the same origin (i.e., MMHg from food), and are representative of Hg photochemistry in the water column of the mammal ecosystem. MDF signatures of Hg compounds indicate that MMHg is demethylated in vivo before being stored in the muscle, and the iHg formed is stored in the liver, and to a lesser extent in the kidney, before excretion. Thus, Hg CSIC analysis in mammals can be a powerful tool for tracing the metabolic response to Hg exposure.

Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism

NARCIS (Netherlands)

Boughlala, Z.; Guerra, C.F.; Bickelhaupt, F.M.

2016-01-01

We have analyzed the structure and bonding of gas-phase Cl X and [HCl X](+) complexes for X+ = H+, CH3+, Li+, and Na+, using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl- and HCl for the various

SO2 absorption in EmimCl-TEG deep eutectic solvents.

Science.gov (United States)

Yang, Dezhong; Zhang, Shaoze; Jiang, De-En; Dai, Sheng

2018-05-23

Deep eutectic solvents (DESs) based on 1-ethyl-3-methylimidazolium chloride (EmimCl) and triethylene glycol (TEG) with different molar ratios (from 6 : 1 to 1 : 1) were prepared. FTIR and theoretical calculation indicated that the C2-H on the imidazolium ring form hydrogen bonds with the hydroxyl group rather than the ether O atom of the TEG. The EmimCl-TEG DESs can efficiently capture SO2; in particular, EmimCl-TEG (6 : 1) can capture 0.54 g SO2 per gram of solvent at 0.10 atm and 20 °C, the highest absorption amount for DESs under the same conditions. Theoretical calculation showed that the high SO2 absorption capacity was mainly due to the strong charge-transfer interaction between SO2 and the anion Cl-. Moreover, SO2 desorption in the DESs can be controlled by tuning the interaction between EmimCl and TEG, and the DESs can be cycled many times.

Isotopic Hg in an Allende carbon-rich residue

International Nuclear Information System (INIS)

Reed, G.W. Jr.; Jovanovic, S.

1990-01-01

A carbon-rich residue from Allende subjected to stepwise heating yielded two isotopically resolvable types of Hg: one with an (Hg-196)/(Hg-202) concentration ratio the same as terrestrial (monitor) Hg; the other enriched in Hg-196 relative to Hg-202 by about 60 percent. Hg with the 202 isotope enriched relative to 196, as is found in bulk Allende, was not observed. Whether the result of mass fractionation or nucleosynthesis, the distinct types of Hg entered different carrier phases and were not thermally mobilized since the accretion of the Allende parent body. 9 refs

40 CFR 60.4142 - Hg allowance allocations.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Hg allowance allocations. 60.4142... Coal-Fired Electric Steam Generating Units Hg Allowance Allocations § 60.4142 Hg allowance allocations. (a)(1) The baseline heat input (in MMBtu) used with respect to Hg allowance allocations under...

Shear bond strength of composite to deep dentin after treatment with two different collagen cross-linking agents at varying time intervals.

Science.gov (United States)

Srinivasulu, S; Vidhya, S; Sujatha, M; Mahalaxmi, S

2012-01-01

This in vitro study evaluated the shear bond strength of composite resin to deep dentin using a total etch adhesive after treatment with two collagen cross-linking agents at varying time intervals. Thirty freshly extracted human maxillary central incisors were sectioned longitudinally into equal mesial and distal halves (n=60). The proximal deep dentin was exposed, maintaining a remaining dentin thickness (RDT) of approximately 1 mm. The specimens were randomly divided into three groups based on the surface treatment of dentin prior to bonding as follows: group I (n=12, control): no prior dentin surface treatment; group II (n=24): dentin surface pretreated with 10% sodium ascorbate; and group III (n=24): dentin surface pretreated with 6.5% proanthocyanidin. Groups II and III were further subdivided into two subgroups of 12 specimens each, based on the pretreatment time of five minutes (subgroup A) and 10 minutes (subgroup B). Shear bond strength of the specimens was tested with a universal testing machine, and the data were statistically analyzed. Significantly higher shear bond strength to deep dentin was observed in teeth treated with 10% sodium ascorbate (group II) and 6.5% proanthocyanidin (group III) compared to the control group (group I). Among the collagen cross-linkers used, specimens treated with proanthocyanidin showed significantly higher shear bond strength values than those treated with sodium ascorbate. No significant difference was observed between the five-minute and 10-minute pretreatment times in groups II and III. It can be concluded that dentin surface pretreatment with both 10% sodium ascorbate and 6.5% proanthocyanidin resulted in significant improvement in bond strength of resin composite to deep dentin.

Parental bonding and depression: personality as a mediating factor.

Science.gov (United States)

Avagianou, Penelope-Alexia; Zafiropoulou, Maria

2008-01-01

According to Bowlby's theory of attachment, the role of early experience and parenting is of crucial importance to child development and mental health. In addition, several research findings suggest that parental bonding and different types of attachment play a crucial role in personality development. The present study examines the association between parental bonding experiences (lack of parental care, overprotection or both) and depression during adulthood. The objective of the present study was to evaluate different personality dimensions as possible mediators of the relation between perceptions of parental bonding and depressive symptoms in adult life. 181 participants (15- 49-years-old) completed the Parental Bonding Instrument (PBI), the Beck Depression Inventory (BDI) and the 16 Personality Factor Questionnaire (16PF). The results show that lack of parental care and overprotection is linked with depressive symptoms and a number of personality characteristics, such as low self-esteem, introversion, distress and emotional instability. In contrast, high care and low protection (optimal bonding) is linked with increased self-confidence, less distress and less depressive symptoms. The results presented here are in line with Bowlby's theory of attachment and show that parental bonding is linked with problematic personality development and psychopathology. The present study provided evidence that personality factors may mediate the observed relationship between parental rearing style and depression. The potential causal mechanisms warrant longitudinal evaluation.

Catalytic Hydrodechlorination of Trichlorobenzenes with Pd(PhenCl2 as Catalyst Precursor

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Guanlin Zhang

2015-01-01

Full Text Available We reported the catalytic hydrodechlorination (HDC of trichlorobenzenes by an organometallic compound Pd(PhenCl2 as a catalyst precursor. The catalyst precursor was prepared by chemical coordination reaction and characterized by FTIR and 1H NMR techniques. The HDC performance of Pd(PhenCl2 as catalyst precursor was evaluated on 1,2,3-, 1,2,4-, and 1,3,5-trichlorobenzenes (TCBs. All TCBs could be converted to dechlorination products with high conversion. Products distribution was closely related with the substrate structures and C-Cl bond energies. A reasonable reaction mechanism was also proposed.

Biosynthesis of micro- and nanocrystals of Pb (II), Hg (II) and Cd (II) sulfides in four Candida species: a comparative study of in vivo and in vitro approaches.

Science.gov (United States)

Cuéllar-Cruz, Mayra; Lucio-Hernández, Daniela; Martínez-Ángeles, Isabel; Demitri, Nicola; Polentarutti, Maurizio; Rosales-Hoz, María J; Moreno, Abel

2017-03-01

Nature produces biominerals (biogenic minerals) that are synthesized as complex structures, in terms of their physicochemical properties. These biominerals are composed of minerals and biological macromolecules. They are produced by living organisms and are usually formed through a combination of chemical, biochemical and biophysical processes. Microorganisms like Candida in the presence of heavy metals can biomineralize those metals to form microcrystals (MCs) and nanocrystals (NCs). In this work, MCs and NCs of PbS, HgS or HgCl 2 as well as CdS are synthesized both in vitro (gels) and in vivo by four Candida species. Our in vivo results show that, in the presence of Pb 2+ , Candida cells are able to replicate and form extracellular PbS MCs, whereas in the presence of Hg 2+ and Cd 2+ , they did synthesize intercellular MCs from HgS or HgCl 2 and CdS NCs respectively. The MCs and NCs biologically obtained in Candida were compared with those PbS, HgS and CdS crystals synthetically obtained in vitro through the gel method (grown either in agarose or in sodium metasilicate hydrogels). This is, to our knowledge, the first time that the biosynthesis of the various MCs and NCs (presented in several species of Candida) has been reported. This biosynthesis is differentially regulated in each of these pathogens, which allows them to adapt and survive in different physiological and environmental habitats. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Fluorescence spectroscopic study of the aggregation behavior of non-cross-linked and cross-linked poly(alkylmethyldiallylammonium bromides) having decyl, octyl, and hexyl side chains in aqueous solution

NARCIS (Netherlands)

Wang, G.J; Engberts, J.B.F.N.

1996-01-01

The conformational state of a series of non-cross-linked and cross-linked poly(alkylmethyldiallylammonium bromides) bearing decyl, octyl, and hexyl side chains ((CL)-CopolC1-10, (CL)-CopolC1-8, and (CL)-CopolC1-6, respectively) in aqueous solutions were investigated by fluorescence spectroscopy

Simultaneous Removal of Hg(II and Phenol Using Functionalized Activated Carbon Derived from Areca Nut Waste

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Lalhmunsiama

2017-07-01

Full Text Available Areca nut waste was utilized to obtain high surface area activated carbon (AC, and it was further functionalized with succinic anhydride under microwave irradiation. The surface morphology and surface functional groups of the materials were discussed with the help of scanning electron microscope(SEM images and fourier transform infra-red (FT-IR analysis. The specific surface area of the AC and functionalized-AC was obtained by the Brunauer-Emmett-Teller (BET method, and found to be 367.303 and 308.032 m2/g, respectively. Batch experiments showed that higher pH favoured the removal of Hg(II, whereas the phenol removal was slightly affected by the changes in the solution pH. The kinetic data followed pseudo-first order kinetic model, and intra-particle diffusion played a significant role in the removal of both pollutants. The maximum sorption capacity of Hg(II and phenol were evaluated using Langmuir adsorption isotherms, and found to be 11.23 and 5.37 mg/g, respectively. The removal of Hg(II was significantly suppressed in the presence of chloride ions due to the formation of a HgCl2 species. The phenol was specifically adsorbed, forming the donor–acceptor complexes or π–π electron interactions at the surface of the solid. Further, a fixed-bed column study was conducted for both Hg(II and phenol. The loading capacity of the column was estimated using the nonlinear Thomas equation, and found to be 2.49 and 2.70 mg/g, respectively. Therefore, the study showed that functionalized AC obtained from areca nut waste could be employed as a sustainable adsorbent for the simultaneous removal of Hg(II and phenol from polluted water.

Oxidative stress in MeHg-induced neurotoxicity

Energy Technology Data Exchange (ETDEWEB)

Farina, Marcelo, E-mail: farina@ccb.ufsc.br [Departamento de Bioquimica, Centro de Ciencias Biologicas, Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil); Aschner, Michael [Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN (United States); Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN (United States); Rocha, Joao B.T., E-mail: jbtrocha@yahoo.com.br [Departamento de Quimica, Centro de Ciencias Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS (Brazil)

2011-11-15

Methylmercury (MeHg) is an environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. Although the molecular mechanisms mediating MeHg-induced neurotoxicity are not completely understood, several lines of evidence indicate that oxidative stress represents a critical event related to the neurotoxic effects elicited by this toxicant. The objective of this review is to summarize and discuss data from experimental and epidemiological studies that have been important in clarifying the molecular events which mediate MeHg-induced oxidative damage and, consequently, toxicity. Although unanswered questions remain, the electrophilic properties of MeHg and its ability to oxidize thiols have been reported to play decisive roles to the oxidative consequences observed after MeHg exposure. However, a close examination of the relationship between low levels of MeHg necessary to induce oxidative stress and the high amounts of sulfhydryl-containing antioxidants in mammalian cells (e.g., glutathione) have led to the hypothesis that nucleophilic groups with extremely high affinities for MeHg (e.g., selenols) might represent primary targets in MeHg-induced oxidative stress. Indeed, the inhibition of antioxidant selenoproteins during MeHg poisoning in experimental animals has corroborated this hypothesis. The levels of different reactive species (superoxide anion, hydrogen peroxide and nitric oxide) have been reported to be increased in MeHg-exposed systems, and the mechanisms concerning these increments seem to involve a complex sequence of cascading molecular events, such as mitochondrial dysfunction, excitotoxicity, intracellular calcium dyshomeostasis and decreased antioxidant capacity. This review also discusses potential therapeutic strategies to counteract MeHg-induced toxicity and oxidative stress, emphasizing the use of organic selenocompounds, which generally present higher affinity for MeHg when compared to the classically

Crystal structures of ZnCl2·2.5H2O, ZnCl2·3H2O and ZnCl2·4.5H2O

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Erik Hennings

2014-12-01

Full Text Available The formation of different complexes in aqueous solutions is an important step in understanding the behavior of zinc chloride in water. The structure of concentrated ZnCl2 solutions is governed by coordination competition of Cl− and H2O around Zn2+. According to the solid–liquid phase diagram, the title compounds were crystallized below room temperature. The structure of ZnCl2·2.5H2O contains Zn2+ both in a tetrahedral coordination with Cl− and in an octahedral environment defined by five water molecules and one Cl− shared with the [ZnCl4]2− unit. Thus, these two different types of Zn2+ cations form isolated units with composition [Zn2Cl4(H2O5] (pentaaqua-μ-chlorido-trichloridodizinc. The trihydrate {hexaaquazinc tetrachloridozinc, [Zn(H2O6][ZnCl4]}, consists of three different Zn2+ cations, one of which is tetrahedrally coordinated by four Cl− anions. The two other Zn2+ cations are each located on an inversion centre and are octahedrally surrounded by water molecules. The [ZnCl4] tetrahedra and [Zn(H2O6] octahedra are arranged in alternating rows parallel to [001]. The structure of the 4.5-hydrate {hexaaquazinc tetrachloridozinc trihydrate, [Zn(H2O6][ZnCl4]·3H2O}, consists of isolated octahedral [Zn(H2O6] and tetrahedral [ZnCl4] units, as well as additional lattice water molecules. O—H...O hydrogen bonds between the water molecules as donor and ZnCl4 tetrahedra and water molecules as acceptor groups leads to the formation of a three-dimensional network in each of the three structures.

High density liquid structure enhancement in glass forming aqueous solution of LiCl

Science.gov (United States)

Camisasca, G.; De Marzio, M.; Rovere, M.; Gallo, P.

2018-06-01

We investigate using molecular dynamics simulations the dynamical and structural properties of LiCl:6H2O aqueous solution upon supercooling. This ionic solution is a glass forming liquid of relevant interest in connection with the study of the anomalies of supercooled water. The LiCl:6H2O solution is easily supercooled and the liquid state can be maintained over a large decreasing temperature range. We performed simulations from ambient to 200 K in order to investigate how the presence of the salt modifies the behavior of supercooled water. The study of the relaxation time of the self-density correlation function shows that the system follows the prediction of the mode coupling theory and behaves like a fragile liquid in all the range explored. The analysis of the changes in the water structure induced by the salt shows that while the salt preserves the water hydrogen bonds in the system, it strongly affects the tetrahedral hydrogen bond network. Following the interpretation of the anomalies of water in terms of a two-state model, the modifications of the oxygen radial distribution function and the angular distribution function of the hydrogen bonds in water indicate that LiCl has the role of enhancing the high density liquid component of water with respect to the low density component. This is in agreement with recent experiments on aqueous ionic solutions.

Silylene-Nickel Promoted Cleavage of B-O Bonds: From Catechol Borane to the Hydroborylene Ligand.

Science.gov (United States)

Hadlington, Terrance J; Szilvási, Tibor; Driess, Matthias

2017-06-19

The first 16 valence electron [bis(NHC)](silylene)Ni 0 complex 1, [( TMS L)ClSi:→Ni(NHC) 2 ], bearing the acyclic amido-chlorosilylene ( TMS L)ClSi: ( TMS L=N(SiMe 3 )Dipp; Dipp=2,6-Pr i 2 C 6 H 4 ) and two NHC ligands (N-heterocyclic carbene=:C[(Pr i )NC(Me)] 2 ) was synthesized in high yield and structurally characterized. Compound 1 is capable of facile dihydrogen activation under ambient conditions to give the corresponding HSi-NiH complex 2. Most notably, 1 reacts with catechol borane to afford the unprecedented hydroborylene-coordinated (chloro)(silyl)nickel(II) complex 3, {[cat( TMS L)Si](Cl)Ni←:BH(NHC) 2 }, via the cleavage of two B-O bonds and simultaneous formation of two Si-O bonds. The mechanism for the formation of 3 was rationalized by means of DFT calculations, which highlight the powerful synergistic effects of the Si:→Ni moiety in the breaking of incredibly strong B-O bonds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Treasury bond volatility and uncertainty about monetary policy

NARCIS (Netherlands)

Arnold, I.J.M.; Vrugt, E.B.

2010-01-01

We show that dispersion-based uncertainty about the future course of monetary policy is the single most important determinant of Treasury bond volatility across all maturities. The link between Treasury bond volatility and uncertainty about macroeconomic variables is much stronger than for the more

(E-2-(5-Chloro-2-hydroxybenzylidene-N-cyclohexylhydrazine-1-carbothioamide

Directory of Open Access Journals (Sweden)

Md. Azharul Arafath

2017-01-01

Full Text Available In the title compound, C14H18ClN3OS, the phenol ring is almost coplanar with the hydrazinecarbothioamide moiety, making a dihedral angle of 6.92 (8°. The cyclohexane ring has a chair conformation and the conformation about the C=N bond is E. In the crystal, molecules are linked by N—H...O and O—H...S hydrogen bonds, forming inversion dimers with an R22(14 ring motif flanked by two R22(6 ring motifs. The dimers are linked by short Cl...Cl interactions, forming layers parallel to the ab plane.

Effect of nanoscale surface roughness on the bonding energy of direct-bonded silicon wafers

Science.gov (United States)

Miki, N.; Spearing, S. M.

2003-11-01

Direct wafer bonding of silicon wafers is a promising technology for manufacturing three-dimensional complex microelectromechanical systems as well as silicon-on-insulator substrates. Previous work has reported that the bond quality declines with increasing surface roughness, however, this relationship has not been quantified. This article explicitly correlates the bond quality, which is quantified by the apparent bonding energy, and the surface morphology via the bearing ratio, which describes the area of surface lying above a given depth. The apparent bonding energy is considered to be proportional to the real area of contact. The effective area of contact is defined as the area sufficiently close to contribute to the attractive force between the two bonding wafers. Experiments were conducted with silicon wafers whose surfaces were roughened by a buffered oxide etch solution (BOE, HF:NH4F=1:7) and/or a potassium hydroxide solution. The surface roughness was measured by atomic force microscopy. The wafers were direct bonded to polished "monitor" wafers following a standard RCA cleaning and the resulting bonding energy was measured by the crack-opening method. The experimental results revealed a clear correlation between the bonding energy and the bearing ratio. A bearing depth of ˜1.4 nm was found to be appropriate for the characterization of direct-bonded silicon at room temperature, which is consistent with the thickness of the water layer at the interface responsible for the hydrogen bonds that link the mating wafers.

Covalency in lanthanides. An X-ray absorption spectroscopy and density functional theory study of LnCl6(x-) (x = 3, 2).

Science.gov (United States)

Löble, Matthias W; Keith, Jason M; Altman, Alison B; Stieber, S Chantal E; Batista, Enrique R; Boland, Kevin S; Conradson, Steven D; Clark, David L; Lezama Pacheco, Juan; Kozimor, Stosh A; Martin, Richard L; Minasian, Stefan G; Olson, Angela C; Scott, Brian L; Shuh, David K; Tyliszczak, Tolek; Wilkerson, Marianne P; Zehnder, Ralph A

2015-02-25

Covalency in Ln-Cl bonds of Oh-LnCl6(x-) (x = 3 for Ln = Ce(III), Nd(III), Sm(III), Eu(III), Gd(III); x = 2 for Ln = Ce(IV)) anions has been investigated, primarily using Cl K-edge X-ray absorption spectroscopy (XAS) and time-dependent density functional theory (TDDFT); however, Ce L3,2-edge and M5,4-edge XAS were also used to characterize CeCl6(x-) (x = 2, 3). The M5,4-edge XAS spectra were modeled using configuration interaction calculations. The results were evaluated as a function of (1) the lanthanide (Ln) metal identity, which was varied across the series from Ce to Gd, and (2) the Ln oxidation state (when practical, i.e., formally Ce(III) and Ce(IV)). Pronounced mixing between the Cl 3p- and Ln 5d-orbitals (t2g* and eg*) was observed. Experimental results indicated that Ln 5d-orbital mixing decreased when moving across the lanthanide series. In contrast, oxidizing Ce(III) to Ce(IV) had little effect on Cl 3p and Ce 5d-orbital mixing. For LnCl6(3-) (formally Ln(III)), the 4f-orbitals participated only marginally in covalent bonding, which was consistent with historical descriptions. Surprisingly, there was a marked increase in Cl 3p- and Ce(IV) 4f-orbital mixing (t1u* + t2u*) in CeCl6(2-). This unexpected 4f- and 5d-orbital participation in covalent bonding is presented in the context of recent studies on both tetravalent transition metal and actinide hexahalides, MCl6(2-) (M = Ti, Zr, Hf, U).

No solid solution compounds in between the binaries. Syntheses and crystal structures of Nb(Br{sub 0.62(4)}Cl{sub 0.38(4)}){sub 2}Cl{sub 2} and NbI{sub 2}Cl{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Reckeweg, Olaf; Schleid, Thomas [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie

2018-04-01

The anion-mixed niobium tetrahalides Nb(Br{sub 0.62(4)}Cl{sub 0.38(4)}){sub 2}Cl{sub 2} and NbI{sub 2}Cl{sub 2} were obtained by heating NbBr{sub 5} with NbCl{sub 5} and NbI{sub 5} with NbCl{sub 5}, respectively, in equimolar ratios with niobium metal in evacuated, torch-sealed silica ampoules at 720 K for 3 days. The orthorhombic title compounds form as very brittle black needles and were characterized by single-crystal X-ray diffraction [space group: Immm, Z=4; a=704.27(6), b=824.13(7), c=929.64(8) pm for Nb(Br{sub 0.62(4)}Cl{sub 0.38(4)}){sub 2}Cl{sub 2} and a=753.76(6), b=829.38(7) and c=983.41(8) pm for NbI{sub 2}Cl{sub 2}]. Surprisingly enough, these mixed-anionic halides are not isostructural with either NbCl{sub 4}, NbBr{sub 4} or NbI{sub 4}, but crystallize isotypically with TaI{sub 2}Cl{sub 2}, thus being examples for differential site occupancy stabilized materials. Structural features of other niobium(IV) halides are compiled and compared to those of Nb(Br{sub 0.62(4)}Cl{sub 0.38(4)}){sub 2}Cl{sub 2} and NbI{sub 2}Cl{sub 2}. Except for NbF{sub 4}, they all exhibit chains of trans-edge connected [NbX{sub 6}]{sup 2-} octahedra, which allow Peierls distortions to form Nb-Nb single bonds. The packing of these chains differ, however, depending on the actual halide or mixed-halide combination.

Comparing the influence of selenite (Se4+) and selenate (Se6+) on the inhibition of the mercury (Hg) phytotoxicity to pak choi.

Science.gov (United States)

Tran, Thi Anh Thu; Dinh, Quang Toan; Cui, Zeiwei; Huang, Jie; Wang, Dan; Wei, Tianjiao; Liang, Dongli; Sun, Xin; Ning, Ping

2018-01-01

Selenite (Se (IV)) and selenate (Se (IV)) have recently been demonstrated to be equally effective in inhibiting mercury (Hg) phytotoxicity to plants. This assertion is still unclear. In this study, we aimed to explore the potential effects of Se species (Se 4+ and Se 6+ ) on the inhibition of the mercury (Hg) bioavailability to pak choi in dry land. Pot experiments with exposure to different dosages of mercuric chloride (HgCl 2 ) and selenite (Na 2 SeO 3 ) or selenate (Na 2 SeO 4 ) were treated. To compare the influence of Se (IV) and Se (VI) on the bioaccumulation and bioavailability of Hg, the levels of total Hg in different pak choi (Brassica chinensis L.) tissues (roots and shoots) and the distribution changes of Hg fractions in soil before planting and after harvest were determined as well as the Hg I R values in soils (relative binding intensity) were analyzed. Results showed that application Se (IV) reduced the concentrations of Hg in pak choi roots more than Se (VI). Hg concentrations were also decreased in pak choi shoots in Se (IV) treatments, while which notably increased in Se (VI) treatments. Thus, Se (IV) plays a more important role than Se (VI) in limiting the absorption and bioaccumulation of Hg in pak choi. Moreover, this inhibition may only significantly occur when Se (IV) is at an appropriate level (2.5mg/kg). In addition, the good correlations between the proportions of mobile Hg fractions (soluble and exchangeable fractions), I R values with the Hg concentrations in plants were observed. This affirmed the importance of the Hg fractions transformation and the I R indicator of Hg in the assessment of their bioavailability. Our findings regarding the importance of Se (IV) influence in reducing Hg bioaccumulation not only provided the correct appraisal about the effect of Se species on the inhibition of the Hg phytotoxicity to pak choi in dry land, but also be a good reference for selecting Se fertilizer forms (Se 4+ or Se 6+ ). Copyright © 2017

Ab initio study of structural, electronic and optical properties of MnHg(SCN)4 and FeHg(SCN)4

International Nuclear Information System (INIS)

He, K.H.; Zheng, G.; Chen, G.; Lue, T.; Wan, M.; Ji, G.F.

2007-01-01

The structural, electronic and optical properties of MnHg(SCN) 4 and FeHg(SCN) 4 were studied by means of quantum-mechanical calculations based on the density-functional theory and pseudopotential method. The lattice constants can be compared with the experimental values when the effects of temperature are considered. The peaks of partial density of states of S, C, N and Hg of FeHg(SCN) 4 have a tendency of shifting to the higher energy levels relative to those of MnHg(SCN) 4 . The distributions of the 3d electronic states in the transition metal atoms show quite large difference and decide different optical properties. We found that absorptional peaks of FeHg(SCN) 4 lag behind those of MnHg(SCN) 4 and the peak in the infrared range has a higher absorptional intensity, which are in accord with the experimental results. By analyzing the distributions and transitions of the 3d electronic states, we explained the different absorption phenomena

Compton profiles and electronic structure of HgBr{sub 2} and HgI{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Ahmed, G.; Dashora, Alpa [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur, 313001 Rajasthan (India); Sharma, M. [Physics Division, State Forensic Science Laboratory, Jaipur, 302016 Rajasthan (India); Ahuja, B.L. [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur, 313001 Rajasthan (India)], E-mail: blahuja@yahoo.com

2010-02-15

In this paper, we present the first-ever experimental Compton line shapes of HgBr{sub 2} and HgI{sub 2} using {sup 137}Cs Compton spectrometer. To compare our experimental momentum densities, we have computed the Compton profiles using Hartree-Fock and density functional theory within linear combination of atomic orbitals. We have also computed the energy bands and density of states using the linear combination of atomic orbitals and full potential linearized augmented plane wave method. On the basis of equal-valence-electron-density profiles, it is seen that HgI{sub 2} is more covalent than HgBr{sub 2} which is in agreement with the valence charge densities. The experimental isotropic profiles are found to be relatively in better agreement with the Hartree-Fock data. We have also discussed the photoluminescence and detection properties of both the halides.

Hg(+) Frequency Standards

Science.gov (United States)

Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

2000-01-01

In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

Hg transfer from contaminated soils to plants and animals

NARCIS (Netherlands)

Rodrigues, S.M.; Henriques, B.; Reis, A.T.; Duarte, A.C.; Pereira, E.; Romkens, P.F.A.M.

2012-01-01

Understanding the transfer of mercury (Hg) from soil to crops is crucial due to Hg toxicity and Hg occurrence in terrestrial systems. Previous research has shown that available Hg in soils contributes to plant Hg levels. Plant Hg concentrations are related to soil conditions and plant

Fluorescent probes for "off-on" highly sensitive detection of Hg²⁺ and L-cysteine based on nitrogen-doped carbon dots.

Science.gov (United States)

Zhang, Yi; Cui, Peipei; Zhang, Feng; Feng, Xiaoting; Wang, Yaling; Yang, Yongzhen; Liu, Xuguang

2016-05-15

Fluorescent nitrogen-doped carbon dots (NCDs) were synthesized by a facile, and low-cost one-step hydrothermal strategy using citric acid as carbon source and ammonia solution as nitrogen source for the first time. The obtained NCDs show stable blue fluorescence with a high quantum yield of 35.4%, along with the fluorescence lifetime of ca. 6.75 ns. Most importantly, Hg(2+) can completely quench the fluorescence of NCDs as a result of the formation of a non-fluorescent stable NCDs-Hg(2+) complex. Static fluorescence quenching towards Hg(2+) is proved by the Stern-Volmer equation, ultraviolet-visible absorption spectra, temperature dependent quenching and fluorescence lifetime measurements. Subsequently, the fluorescence of the NCDs-Hg(2+) system is completely recovered with the addition L-cysteine (L-Cys) owing to the dissociation of NCDs-Hg(2+) complex to form a more stable Hg(2+)-L-Cys complex by Hg(2+)-S bonding. Therefore, such NCDs can be used as an effective fluorescent "turn-off" probe for rapid, rather highly selective and sensitive detection of Hg(2+), with a limit of detection (LOD) as low as 1.48 nM and a linear detection range of 0-10 μM. Interestingly, NCDs-Hg(2+) system can be conveniently employed as a fluorescent "turn-on" sensor for highly selective and sensitive detection of L-Cys with a low LOD of 0.79 nM and a wide linear detection range of 0-50 μM. Further, the sensitivity of NCDs to Hg(2+) is preserved in tap water with a LOD of 1.65 nM and a linear detection range of 0-10 μM. Copyright © 2016 Elsevier B.V. All rights reserved.

Bioaccumulation of As, Cd, Cr, Hg(II), and MeHg in killifish (Fundulus heteroclitus) from amphipod and worm prey

Energy Technology Data Exchange (ETDEWEB)

Dutton, Jessica, E-mail: dutton.jess@gmail.com; Fisher, Nicholas S., E-mail: nfisher@notes.cc.sunysb.edu

2011-08-15

Elevated metal levels in fish are a concern for the fish themselves, their predators, and possibly humans who consume contaminated seafood. Metal bioaccumulation models often rely on assimilation efficiencies (AEs) of ingested metals and loss rate constants after dietary exposure (k{sub ef}s). These models can be used to better understand processes regulating metal accumulation and can be used to make site-specific predictions of metal concentrations in animal tissues. Fish often consume a varied diet, and prey choice can influence these two parameters. We investigated the trophic transfer of As, Cd, Cr, Hg(II), and methylmercury (MeHg) from a benthic amphipod (Leptocheirus plumulosus) and an oligochaete (Lumbriculus variegatus) to killifish (Fundulus heteroclitus) using gamma-emitting radioisotopes. Except for MeHg, AEs varied between prey type. AEs were highest for MeHg (92%) and lowest for Cd (2.9-4.5%) and Cr (0.2-4%). Hg(II) showed the largest AE difference between prey type (14% amphipods, 24% worms). For Cd and Hg(II) k{sub ef}s were higher after consuming amphipods than consuming worms. Tissue distribution data shows that Cd and Hg(II) were mainly associated with the intestine, whereas As and MeHg were transported throughout the body. Calculated trophic transfer factors (TTFs) suggest that MeHg is likely to biomagnify at this trophic step at all ingestion rates, whereas As, Cd, Cr, and Hg(II) will not. Data collected in this study and others indicate that using one prey item to calculate AE and k{sub ef} could lead to an over- or underestimation of these parameters. - Highlights: {yields} We investigated the trophic transfer of metals to killifish from amphipod and worm prey. {yields} Prey choice influences metal accumulation from the diet. {yields} Only MeHg is likely to biomagnify at this trophic step.

A theoretical investigation of the feasibility of Tannor-Rice type control: Application to selective bond breakage in gas-phase dihalomethanes

DEFF Research Database (Denmark)

Shu, Chuan-Cun; Rozgonyi, Tamas; Gonzalez, Leticia

2012-01-01

Within the math absorption band of CH2BrCl, we theoretically analyze the laser-induced control of the Br/Cl branching ratio, Br + CH2Cl ← CH2BrCl → CH2Br + Cl, with CH2BrCl initially in its vibrational ground state. For weak-field excitation, the Br/Cl branching ratio increases as a function of w......-Rice type laser control mechanism for selective bond breakage in CH2BrCl cannot take place without accompanying photoionization....

Co-existence of long-range order and spin fluctuation in a new geometric frustration series M2(OH)3Cl

International Nuclear Information System (INIS)

Zheng, X.G.; Hagihala, Masato; Toriyi, Takato

2007-01-01

Recently, we observed the co-existence of a long-range magnetic order and spin fluctuation in a clean compound of clinoatacamite, Cu 2 (OH) 3 Cl (PRL95 (2005) 057201). The present work reports magnetic studies on other compounds of this transition metal series M 2 (OH) 3 Cl, where M represents three-dimensional (3D)-electron magnetic ions of Co 2+ , Fe 2+ , etc., respectively. The present study shows that this co-existence is a common feature of the M 2 Cl(OH) 3 series, no matter whether it is anti-ferromagnetic, as in the case of Fe 2 (OH) 3 Cl (T N =15 K), or ferromagnetic, as in the case of Co 2 (OH) 3 Cl (T C =10.5 K). These compounds show a 3D network of corner-sharing tetrahedrons for the magnetic ions. The tetrahedron is slightly tilted with roughly 10% longer distance between the M-M bonded by Cl than those bonded by O and this distortion is suspected to be responsible for the partial order. This research suggests that the transition metal hydroxyhalide M 2 Cl(OH) 3 series are new geometric frustration system on tetrahedral lattice for d-electron spins

A study of roll-bonding MS90 alloy to steel utilizing chromized interlayer

International Nuclear Information System (INIS)

Tolaminejad, B.; Arabi, H.

2008-01-01

This article describes a study of the application of a roll bonding technique to MS90(CuZn10) alloy strips and steel sheets using a chromized interlayer. It was found that the overall bond between these two metals resulted from two different types of bonds: a block bond, linking the MS90 alloy strips and chromium topcoat layer, and a blank bond, linking the MS90 alloy strips and bare steel surface in the area where the chromium coating has been fragmented. This study investigated the effects of plating time on the thickness of the coating layers and of the area fraction of the blank bond on the bond strength. The overall bond strength depends mainly on the strength and the area fraction of the blank bond. A linear relationship model exists between the overall bond strength and the area fraction of the blank bond. The bond strength of the blank bond was eight times greater than that of the block bond. The area fraction of the blank bond increased with increasing the coating thickness up to 55 μm, but thereafter decreased due to the rotation of the chromium blocks

Determination of Cl, K, Rb, Zn, Se and Hg in paprika by neutron activation analysis

Energy Technology Data Exchange (ETDEWEB)

Karimian-Teherani, D; Tehrani, N [Oesterreichische Studiengesellschaft fuer Atomenergie G.m.b.H., Seibersdorf. Forschungszentrum; Kiss, I [Kozponti Elelmiszeripari Kutato Intezet, Budapest (Hungary)

1979-10-30

Various samples of Hungarian spice paprika (powdered) were analysed for their Cl, K, Rb and Zn content. Samples of paprika both with and without seeds were studied. The values are reported in ppm (dry weight). Statistical analyses showed significant differences in the trace element contents of most cultivars. In the majority of the cases the increase in the seed content of the samples tended to reduce their trace element content except for Zn.

Preparation of new diatomite-chitosan composite materials and their adsorption properties and mechanism of Hg(II).

Science.gov (United States)

Fu, Yong; Xu, Xiaoxu; Huang, Yue; Hu, Jianshe; Chen, Qifan; Wu, Yaoqing

2017-12-01

A new composite absorbent with multifunctional and environmental-friendly structures was prepared using chitosan, diatomite and polyvinyl alcohol as the raw materials, and glutaraldehyde as a cross-linking agent. The structure and morphology of the composite absorbent, and its adsorption properties of Hg(II) in water were characterized with Fourier transform infrared (FT-IR) spectra, scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET) measurements and ultraviolet-visible (UV-Vis) spectra. The effect of the pH value and contact time on the removal rate and absorbance of Hg(II) was discussed. The adsorption kinetic model and static adsorption isotherm and regeneration of the obtained composite absorbent were investigated. The results indicated that the removal of Hg(II) on the composite absorbent followed a rapid adsorption for 50 min, and was close to the adsorption saturation after 1 h, which is in accord with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. When the pH value, contact time and the mass of the composite absorbent was 3, 1 h and 100 mg, respectively, the removal rate of Hg(II) on the composite absorbent reached 77%, and the maximum adsorption capacity of Hg(II) reached 195.7 mg g -1 .

Preparation of new diatomite–chitosan composite materials and their adsorption properties and mechanism of Hg(II)

Science.gov (United States)

Fu, Yong; Xu, Xiaoxu; Huang, Yue; Hu, Jianshe; Chen, Qifan; Wu, Yaoqing

2017-01-01

A new composite absorbent with multifunctional and environmental-friendly structures was prepared using chitosan, diatomite and polyvinyl alcohol as the raw materials, and glutaraldehyde as a cross-linking agent. The structure and morphology of the composite absorbent, and its adsorption properties of Hg(II) in water were characterized with Fourier transform infrared (FT-IR) spectra, scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET) measurements and ultraviolet–visible (UV–Vis) spectra. The effect of the pH value and contact time on the removal rate and absorbance of Hg(II) was discussed. The adsorption kinetic model and static adsorption isotherm and regeneration of the obtained composite absorbent were investigated. The results indicated that the removal of Hg(II) on the composite absorbent followed a rapid adsorption for 50 min, and was close to the adsorption saturation after 1 h, which is in accord with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. When the pH value, contact time and the mass of the composite absorbent was 3, 1 h and 100 mg, respectively, the removal rate of Hg(II) on the composite absorbent reached 77%, and the maximum adsorption capacity of Hg(II) reached 195.7 mg g−1. PMID:29308226

Corrosion Study and Intermetallics Formation in Gold and Copper Wire Bonding in Microelectronics Packaging

Directory of Open Access Journals (Sweden)

Christopher Breach

2013-07-01

Full Text Available A comparison study on the reliability of gold (Au and copper (Cu wire bonding is conducted to determine their corrosion and oxidation behavior in different environmental conditions. The corrosion and oxidation behaviors of Au and Cu wire bonding are determined through soaking in sodium chloride (NaCl solution and high temperature storage (HTS at 175 °C, 200 °C and 225 °C. Galvanic corrosion is more intense in Cu wire bonding as compared to Au wire bonding in NaCl solution due to the minimal formation of intermetallics in the former. At all three HTS annealing temperatures, the rate of Cu-Al intermetallic formation is found to be three to five times slower than Au-Al intermetallics. The faster intermetallic growth rate and lower activation energy found in this work for both Au/Al and Cu/Al as compared to literature could be due to the thicker Al pad metallization which removed the rate-determining step in previous studies due to deficit in Al material.

Oblate shapes of 200,202,204Hg

International Nuclear Information System (INIS)

Bockisch, A.; Bharuth-Ram, K.; Kleinfeld, A.M.; Lieb, K.P.

1979-01-01

Measurements of the reorientation effect for the first excited 2 + states in 200 , 202 , 204 Hg were performed by exploiting the dependence of the γ-ray yield on Q 2 + for different projectiles. For 200 Hg, a positive quadrupole moment of Q 2 = 0.96 +- 0.11 eb (for negative interference) or Q 2 = 1.11 +- 0.11 eb (for positive interference) was determined indicating an oblate shape. Small positive Q 2 values were also found for 202 Hg and 204 Hg. Nine B(E2) values for excitation of the 2 + , 2 + ' and 4 + states in 196-204 Hg were measured. (orig.) [de

Theoretical study on the alkylation of o-xylene with styrene in AlCl3-ionic liquid catalytic system.

Science.gov (United States)

Cao, Bobo; Du, Jiuyao; Cao, Ziping; Sun, Haitao; Sun, Xuejun; Fu, Hui

2017-06-01

To explore sustainable catalysts with innovative mechanisms, the alkylation mechanism of o-xylene with styrene was studied using DFT method in AlCl 3 -ionic liquid catalytic system. The reaction pathway was consisted of CC coupling and a hydrogen shift, in which two transition states were found and further discussed. The reactive energy catalyzed by superelectrophilic AlCl 2 + (12.6kcal/mol) was distinctly lower than AlCl 3 (43.0kcal/mol), which was determined as the rate-determining step. Mulliken charge along IRC gave a comprehensive understanding of charge distribution and electron transfer in dynamic progress. Bond orders and AIM theory were used to study the nature of chemical bonds and the driving forces in different reaction stages. Copyright © 2017 Elsevier Inc. All rights reserved.

Hg stable isotope analysis by the double-spike method.

Science.gov (United States)

Mead, Chris; Johnson, Thomas M

2010-06-01

Recent publications suggest great potential for analysis of Hg stable isotope abundances to elucidate sources and/or chemical processes that control the environmental impact of mercury. We have developed a new MC-ICP-MS method for analysis of mercury isotope ratios using the double-spike approach, in which a solution containing enriched (196)Hg and (204)Hg is mixed with samples and provides a means to correct for instrumental mass bias and most isotopic fractionation that may occur during sample preparation and introduction into the instrument. Large amounts of isotopic fractionation induced by sample preparation and introduction into the instrument (e.g., by batch reactors) are corrected for. This may greatly enhance various Hg pre-concentration methods by correcting for minor fractionation that may occur during preparation and removing the need to demonstrate 100% recovery. Current precision, when ratios are normalized to the daily average, is 0.06 per thousand, 0.06 per thousand, 0.05 per thousand, and 0.05 per thousand (2sigma) for (202)Hg/(198)Hg, (201)Hg/(198)Hg, (200)Hg/(198)Hg, and (199)Hg/(198)Hg, respectively. This is slightly better than previously published methods. Additionally, this precision was attained despite the presence of large amounts of other Hg isotopes (e.g., 5.0% atom percent (198)Hg) in the spike solution; substantially better precision could be achieved if purer (196)Hg were used.

Interactions of Hg(ii) with oligonucleotides having thymine-thymine mispairs. Optimization of an impedimetric Hg(ii) sensor.

Science.gov (United States)

Kamal, Ajar; She, Zhe; Sharma, Renu; Kraatz, Heinz-Bernhard

2017-05-21

The present work describes the effect of the number of thymine-thymine mispairs in single strand DNA probes on Hg(ii) interactions and further to develop a highly sensitive DNA based impedimetric sensor for Hg(ii) detection. To achieve this goal, the influence of the number of T-T mispairs on the signal response prompted by DNA-Hg(ii) binding interactions was examined on three designed DNA probes: 5'-OH-(CH 2 ) 6 -S-S-(CH 2 ) 6 -AGTCCACACGTTCCTTACGC-3', 5'-OH-(CH 2 ) 6 -S-S-(CH 2 ) 6 -AGTCCACATTTTCCTTTTGC-3', 5'-OH-(CH 2 ) 6 -S-S-(CH 2 ) 6 -AGTCCATTTTTTCCTTTTTT-3' having 2T-T, 4T-T and 6T-T mispairs with identical length, respectively. This study revealed that the number of T-T mispairs plays a critical role in maximizing the signal intensity of DNA-Hg(ii) binding interactions. Based on these results, DNA comprising maximum number of T-T mispairs was further utilized for construction of the Hg(ii) sensor, which exhibited a linear correlation between the change in charge transfer resistance (ΔR CT ) and the concentration of Hg(ii) over the range of 1.0 × 10 -5 M to 1.0 × 10 -10 M with a lower detection limit of 3.2 × 10 -11 M. The selectivity was tested against 12 different metal ions including Hg(ii). The ΔR CT response from Hg(ii) is 3 times higher than the nearest competitor Pb(ii) and approximately 10 times than other ions. The potential application of such a robust and label-free DNA sensor was demonstrated by analyzing environmental samples collected from Lake Ontario.

The link between bond forfeiture and pretrial release mechanism: The case of Dallas County, Texas.

Science.gov (United States)

Clipper, Stephen J; Morris, Robert G; Russell-Kaplan, Amanda

2017-01-01

The goal of this study was to evaluate the efficacy of four pretrial jail release mechanisms (i.e., bond types) commonly used during the pretrial phase of the criminal justice process in terms of their ability to discriminate between defendants failing to appear in court (i.e., bond forfeiture). These include attorney bonds, cash bonds, commercial bail bonds, and release via a pretrial services agency. A multi-treatment propensity score matching protocol was employed to assess between-release-mechanism differences in the conditional probability of failure to appear/bond forfeiture. Data were culled from archival state justice records comprising all defendants booked into the Dallas County, Texas jail during 2008 (n = 29,416). The results suggest that defendants released via commercial bail bonds were less likely to experience failure to appear leading to the bond forfeiture process compared to equivalent defendants released via cash, attorney, and pretrial services bonds. This finding held across different offense categories. The study frames these differences within a discussion encompassing procedural variation within and between each release mechanism, thereby setting the stage for further research and dialog regarding potential justice reform.

The link between bond forfeiture and pretrial release mechanism: The case of Dallas County, Texas.

Directory of Open Access Journals (Sweden)

Stephen J Clipper

Full Text Available The goal of this study was to evaluate the efficacy of four pretrial jail release mechanisms (i.e., bond types commonly used during the pretrial phase of the criminal justice process in terms of their ability to discriminate between defendants failing to appear in court (i.e., bond forfeiture. These include attorney bonds, cash bonds, commercial bail bonds, and release via a pretrial services agency.A multi-treatment propensity score matching protocol was employed to assess between-release-mechanism differences in the conditional probability of failure to appear/bond forfeiture. Data were culled from archival state justice records comprising all defendants booked into the Dallas County, Texas jail during 2008 (n = 29,416.The results suggest that defendants released via commercial bail bonds were less likely to experience failure to appear leading to the bond forfeiture process compared to equivalent defendants released via cash, attorney, and pretrial services bonds. This finding held across different offense categories. The study frames these differences within a discussion encompassing procedural variation within and between each release mechanism, thereby setting the stage for further research and dialog regarding potential justice reform.

Experimental Charge Density Study of Trichromium Linear Metal String Complex – Cr3(dpa)4Cl2

DEFF Research Database (Denmark)

Wu, Lai-Chin; Cheng, Ming-Chuan; Thomsen, Maja Krüger

An experimental and theoretical charge density study, based on Bader’s Quantum Theory: Atoms in Molecule (QTAIM), on a trichromium metal string complex, Cr3(dpa)4Cl2(C2H5OC2H5)x(CH2Cl2)1-x (1, dpa- = bis(2-pyridyl)amido)) is performed. The structure and multipole model of 1 are performed by using...... experimental X-ray diffraction data which are collected at both 100 K using conventional X-ray source (DS1) and 15 K using synchrotron source (DS2). The three chromium metal string is bridged by four dpa- ligands. These tri-chromium metal ions are bonded to each other and terminated by two Cl- ions on the both...... ends, forming a [Cl(1)Cr(1)Cr(2)Cr(3)Cl(2)] linear string. Each Cr atoms are coordinated by four N atoms of each dpa- ligand. This metal string is slightly unsymmetrical at both data sets. The bond distance, from DS1 (DS2), of Cr(1)Cr(2), 2.3480(2) (2.3669(1)) Å, is 0.03 (0.003) Å shorter than Cr...

Bis(hydroxyammonium hexachloridoplatinate(IV–18-crown-6 (1/2

Directory of Open Access Journals (Sweden)

Evgeny Bulatov

2014-01-01

Full Text Available In the title complex, (NH3OH2[PtCl6]·2C12H24O6, the PtIV atom is coordinated by six chloride anions in a slightly distorted octahedral geometry. The Pt—Cl bond lengths are comparable to those reported for other hexachloridoplatinate(IV species. The hydroxyammonium groups act as linkers between the [PtCl6]2− anion and the crown ether molecules. The anion is linked to two hydroxyammonium cations via O—H...Cl hydrogen bonds and each hydroxyammonium moiety is linked to a crown ether molecule by hydrogen bonds between ammonium H atoms and 18-crown-6 O atoms. The crown ether molecules have the classic crown shape in which all O atoms are located in the inner part of the crown ether ring and all –CH2– groups are turned to the outside.

Dislocation-free etching figures in crystals of CdxHg1-xTe solid solutions

International Nuclear Information System (INIS)

Kholina, E.N.; Khazieva, R.A.; Bursak, S.S.; Nevskij, O.B.; Filatov, A.V.; Popovyan, G.Eh.; Suslov, E.V.; Prijmak, A.N.

1988-01-01

Using the method of chemical etching, etching figures formed in areas distributed over Cd x Hg 1-x Te crystal with increased content of impurities consisting of Si,Al,Na,K,Cl,Fe,Ti,Mg and S mainly are revealed. The size of impurity inclusions is >1μm, that is why they cannot be detected either by optical microscopy or local microroentgenospectral analysis. Formation and distribution of impurity inclusions are obviously defined by only the concentration of impurity atoms in the melt. The shape of etching figures does not depend on crystallographical orientation of the crystal-matrix

Electron and electron-phonon effects in quasi-two-dimensional molecular conductor theta-(BETS) sub 4 HgBr sub 4 (C sub 6 H sub 5 Cl): optical investigations at 300-15 K

CERN Document Server

Vlasova, R M; Petrov, B V; Semkin, N D; Zhilyaeva, E I; Bogdanova, O A; Lyubovskaya, R N; Graja, A

2002-01-01

One studied the polarized spectra of reflection and spectra of optical transmission of theta-(BETS) sub 4 HgBr sub 4 (C sub 6 H sub 5 Cl) quasi-two-dimensional molecular conductor within 700-6500 cm sup - sup 1 range under 300-15 K temperatures and within 9000-40000 cm sup - sup 1 under 300 K for two principal directions within crystal plane parallel to conducting layers of BETS molecules. Under 300 K within IR region the spectra are characterized by the intensive essential peculiarities (1200-1400 cm sup - sup 1) caused by electron-oscillation coupling (EOC). At temperature drop within 180-80 K range one observes in the spectra a Lorentz term with omega sub t = 2900 cm sup - sup 1 and three extra bands within 800-1180 cm sup - sup 1 region caused by EOC. The derived results are indicative of unstable structural distortions along two principal directions in a crystal followed by formation of a charge density comparable wave

Superior catalytic effect of TiF3 over TiCl3 in improving the hydrogen sorption kinetics of MgH2: Catalytic role of fluorine anion

International Nuclear Information System (INIS)

Ma, L.-P.; Kang, X.-D.; Dai, H.-B.; Liang, Y.; Fang, Z.-Z.; Wang, P.-J.; Wang, P.; Cheng, H.-M.

2009-01-01

TiF 3 shows a superior catalytic effect over TiCl 3 in improving the hydrogen sorption kinetics of MgH 2 . Combined phase analysis and microstructure characterization suggest that both titanium halide additives react with host MgH 2 in a similar way. However, systematic X-ray photoelectron spectroscopy studies reveal that the incorporated fluorine (F) differs significantly from its analog chlorine (Cl) in terms of bonding state. The asymmetry of F 1s spectra and the sputtering-induced peak shift suggest that, in addition to the Mg-F bond, a new Ti-F-Mg bonding is formed in the TiF 3 -doped MgH 2 . In contrast, only one stable binding state of Cl is identified in the form of MgCl 2 for the TiCl 3 -doped MgH 2 . In combination with the designed experiments, these findings suggest that the generation of active F-containing species may be responsible for the advantage of TiF 3 over TiCl 3 in improving both the absorption and desorption kinetics of MgH 2 . Fundamentally, it emphasizes the functionality of F anion in tuning the activity of compound catalyst

Metal-ligand delocalization and spin density in the CuCl{sub 2} and [CuCl{sub 4}]{sup 2−} molecules: Some insights from wave function theory

Energy Technology Data Exchange (ETDEWEB)

Giner, Emmanuel, E-mail: gnrmnl@unife.it; Angeli, Celestino, E-mail: anc@unife.it [Dipartimento di Scienze Chimiche e Famaceutiche, Universita di Ferrara, Via Fossato di Mortara 17, I-44121 Ferrara (Italy)

2015-09-28

The aim of this paper is to unravel the physical phenomena involved in the calculation of the spin density of the CuCl{sub 2} and [CuCl{sub 4}]{sup 2−} systems using wave function methods. Various types of wave functions are used here, both variational and perturbative, to analyse the effects impacting the spin density. It is found that the spin density on the chlorine ligands strongly depends on the mixing between two types of valence bond structures. It is demonstrated that the main difficulties found in most of the previous studies based on wave function methods come from the fact that each valence bond structure requires a different set of molecular orbitals and that using a unique set of molecular orbitals in a variational procedure leads to the removal of one of them from the wave function. Starting from these results, a method to compute the spin density at a reasonable computational cost is proposed.

Bonding in d9 complexes derived from EPR: Application to CuCl2-4, CuBr2-4, and CdCl2:Cu2+

Science.gov (United States)

Aramburu, J. A.; Moreno, M.

1985-12-01

In this work are reported the theoretical expressions for the [g], hyperfine, and superhyperfine (shf) tensors of a d9 square-planar complex within a molecular orbital (MO) scheme. These expressions include contributions arising from crystal field and charge transfer excitations calculated up to third and second order perturbations, respectively. This makes the present framework more general than those previously used. Through those expressions we have derived from the experimental EPR and optical data the MO coefficients corresponding to the valence b1g(x2-y2), b2g(xy), and eg(xz,yz) levels and also the core polarization contribution K to the hyperfine tensor for the systems CuCl2-4, CuBr2-4, and CdCl2:Cu2+. The 3d charge obtained for CuCl2-4 is equal to 0.61, 0.83, and 0.85 for the antibonding 3b1g, 2b2g, and 2eg levels, respectively. These figures are much closer to the Xα results by Bencini and Gatteschi [J. Am. Chem. Soc. 105, 5535 (1983)] than to those by Desjardins et al. [J. Am. Chem. Soc. 105, 4590 (1983)]. The σ and π covalency for CuBr2-4 are both higher than for CuCl2-4 in accord to the lower electronegativity for bromine. However, only for the antibonding 3b1g level of CuBr2-4 have we obtained an electronic charge lying mainly on ligands. The covalency of CdCl2:Cu2+ is smaller than that found for CuCl2-4, a fact associated to a higher metal-ligand distance for the former. Evidence of this statement are also given from the analysis of crystal-field spectra and isotropic shf constant. The values of K derived for CuCl2-4 (128.1×10-4 cm-1), CuBr2-4 (103.6×10-4 cm-1), and CdCl2:Cu2+ (123.9×10-4 cm-1) point out the dependence of K on the equatorial covalency but also on the existence of axial ligands. The [g] tensor of CuBr2-4 is dominated by the charge transfer contribution while the crystal field one is negative. Finally an analysis of the importance of each one of the involved contributions to the spin-Hamiltonian parameters is reported for the

EPR-spin probe studies of model polymers: separation of covalent cross-linking effects from hydrogen bonding effects in swelled Argonne Premium Coal samples

Energy Technology Data Exchange (ETDEWEB)

Spears, D.R.; Sady, W.; Tucker, D.; Kispert, L.D. (University of Alabama, Tuscaloosa, AL (United States). Chemistry Dept.)

The swelling behaviour of 2-12% cross-linked polystyrene-divinylbenzene (PSDVB) copolymers was examined by an EPR-spin probe technique. It was observed that the mechanism of spin probe inclusion was the intercalation into the matrix rather than diffusion into the pores. The disruption of van der Waals forces between adjacent aromatic rings appeared to be the primary mechanism for pyridine swelling of PSDVB. By comparing the data to results from coal swelling studies it was also inferred that the extent of hydrogen bonding in coal will have a much greater impact on its swelling properties than its covalently cross-linked character. 24 refs., 6 figs.

40 CFR 60.4111 - Alternate Hg designated representative.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Alternate Hg designated representative... Times for Coal-Fired Electric Steam Generating Units Hg Designated Representative for Hg Budget Sources § 60.4111 Alternate Hg designated representative. (a) A certificate of representation under § 60.4113...

Real-Space Bonding Indicator Analysis of the Donor-Acceptor Complexes X3BNY3, X3AlNY3, X3BPY3, and X3AlPY3 (X, Y = H, Me, Cl).

Science.gov (United States)

Mebs, Stefan; Beckmann, Jens

2017-10-12

Calculations of real-space bonding indicators (RSBI) derived from Atoms-In-Molecules (AIM), Electron Localizability Indicator (ELI-D), Non-Covalent Interactions index (NCI), and Density Overlap Regions Indicator (DORI) toolkits for a set of 36 donor-acceptor complexes X 3 BNY 3 (1, 1a-1h), X 3 AlNY 3 (2, 2a-2h), X 3 BPY 3 (3, 3a-3h), and X 3 AlPY 3 (4, 4a-4h) reveal that the donor-acceptor bonds comprise covalent and ionic interactions in varying extents (X = Y = H for 1-4; X = H, Y = Me for 1a-4a; X = H, Y = Cl for 1b-4b; X = Me, Y = H for 1c-4c; X, Y = Me for 1d-4d; X = Me, Y = Cl for 1e-4e; X = Cl, Y = H for 1f-4f; X = Cl, Y = Me for 1g-4g; X, Y = Cl for 1h-4h). The phosphinoboranes X 3 BPY 3 (3, 3a-3h) in general and Cl 3 BPMe 3 (3f) in particular show the largest covalent contributions and the least ionic contributions. The aminoalanes X 3 AlNY 3 (2, 2a-2h) in general and Me 3 AlNCl 3 (2e) in particular show the least covalent contributions and the largest ionic contributions. The aminoboranes X 3 BNY 3 (1, 1a-1h) and the phosphinoalanes X 3 AlPY 3 (4, 4a-4h) are midway between phosphinoboranes and aminoalanes. The degree of covalency and ionicity correlates with the electronegativity difference BP (ΔEN = 0.15) < AlP (ΔEN = 0.58) < BN (ΔEN = 1.00) < AlN (ΔEN = 1.43) and a previously published energy decomposition analysis (EDA). To illustrate the importance of both contributions in Lewis formula representations, two resonance formulas should be given for all compounds, namely, the canonical form with formal charges denoting covalency and the arrow notation pointing from the donor to the acceptor atom to emphasis ionicity. If the Lewis formula mainly serves to show the atomic connectivity, the most significant should be shown. Thus, it is legitimate to present aminoalanes using arrows; however, for phosphinoboranes the canonical form with formal charges is more appropriate.

Ultrafast dynamics of hydrogen bond exchange in aqueous ionic solutions.

Science.gov (United States)

Park, Sungnam; Odelius, Michael; Gaffney, Kelly J

2009-06-04

The structural and dynamical properties of aqueous ionic solutions influence a wide range of natural and biological processes. In these solutions, water has the opportunity to form hydrogen bonds with other water molecules and anions. Knowing the time scale with which these configurations interconvert represents a key factor to understanding the influence of molecular scale heterogeneity on chemical events in aqueous ionic solutions. We have used ultrafast IR spectroscopy and Car-Parrinello molecular dynamics (CPMD) simulations to investigate the hydrogen bond (H-bond) structural dynamics in aqueous 6 M sodium perchlorate (NaClO4) solution. We have measured the H-bond exchange dynamics between spectrally distinct water-water and water-anion H-bond configurations with 2DIR spectroscopy and the orientational relaxation dynamics of water molecules in different H-bond configurations with polarization-selective IR pump-probe experiments. The experimental H-bond exchange time correlates strongly with the experimental orientational relaxation time of water molecules. This agrees with prior observations in water and aqueous halide solutions, and has been interpreted within the context of an orientational jump model for the H-bond exchange. The CPMD simulations performed on aqueous 6 M NaClO4 solution clearly demonstrate that water molecules organize into two radially and angularly distinct structural subshells within the first solvation shell of the perchlorate anion, with one subshell possessing the majority of the water molecules that donate H-bonds to perchlorate anions and the other subshell possessing predominantly water molecules that donate two H-bonds to other water molecules. Due to the high ionic concentration used in the simulations, essentially all water molecules reside in the first ionic solvation shells. The CPMD simulations also demonstrate that the molecular exchange between these two structurally distinct subshells proceeds more slowly than the H-bond

Halogen-bonded network of trinuclear copper(II 4-iodopyrazolate complexes formed by mutual breakdown of chloroform and nanojars

Directory of Open Access Journals (Sweden)

Stuart A. Surmann

2016-11-01

Full Text Available Crystals of bis(tetrabutylammonium di-μ3-chlorido-tris(μ2-4-iodopyrazolato-κ2N:N′tris[chloridocuprate(II] 1,4-dioxane hemisolvate, (C16H36N2[Cu3(C3H2IN23Cl5]·0.5C4H8O or (Bu4N2[CuII3(μ3-Cl2(μ-4-I-pz3Cl3]·0.5C4H8O, were obtained by evaporating a solution of (Bu4N2[{CuII(μ-OH(μ-4-I-pz}nCO3] (n = 27–31 nanojars in chloroform/1,4-dioxane. The decomposition of chloroform in the presence of oxygen and moisture provides HCl, which leads to the breakdown of nanojars to the title trinuclear copper(II pyrazolate complex, and possibly CuII ions and free 4-iodopyrazole. CuII ions, in turn, act as catalyst for the accelerated decomposition of chloroform, ultimately leading to the complete breakdown of nanojars. The crystal structure presented here provides the first structural description of a trinuclear copper(II pyrazolate complex with iodine-substituted pyrazoles. In contrast to related trinuclear complexes based on differently substituted 4-R-pyrazoles (R = H, Cl, Br, Me, the [Cu3(μ-4-I-pz3Cl3] core in the title complex is nearly planar. This difference is likely a result of the presence of the iodine substituent, which provides a unique, novel feature in copper pyrazolate chemistry. Thus, the iodine atoms form halogen bonds with the terminal chlorido ligands of the surrounding complexes [mean length of I...Cl contacts = 3.48 (1 Å], leading to an extended two-dimensional, halogen-bonded network along (-110. The cavities within this framework are filled by centrosymmetric 1,4-dioxane solvent molecules, which create further bridges via C—H...Cl hydrogen bonds with terminal chlorido ligands of the trinuclear complex not involved in halogen bonding.

Simple and green synthesis of piperazine-grafted reduced graphene oxide and its application for the detection of Hg(II)

Science.gov (United States)

Zuo, Yinxiu; Xu, Jingkun; Xing, Huakun; Duan, Xuemin; Lu, Limin; Ye, Guo; Jia, Haiyan; Yu, Yongfang

2018-04-01

In this paper, piperazine-grafted reduced graphene oxide (NH-rGO) was synthesized via a simple and green two-step procedure: (i) opening of the resulting epoxides of graphene oxide (GO) with piperazine (NH) through nucleophilic substitution; (ii) reduction of GO with ascorbic acid. Its structure and morphology were characterized by scanning electron microscopy and x-ray photoelectron spectroscopy. The NH-rGO modified glassy carbon electrode was explored as an electrochemical sensor for the determination of Hg(II) using a differential pulse anodic stripping voltammetry technique. Hg(II) can be efficiently accumulated and deposited on the surface of a modified electrode by strong coordination chemical bonds formed between Hg(II) and NH. And then the anodic stripping current can be significantly enhanced by rGO with the merits of large specific surface area and high conductivity, which served as a signal amplifier, finally realizing the highly sensitive determination of Hg(II). The experimental parameters including the pH value of the acetate buffer, deposition potential and deposition time were optimized. Under optimal conditions, the developed sensor exhibited a wide linear range from 0.4-12 000 nM with a low limit of detection of 0.2 nM, which is well below the guideline value in drinking water set by the WHO. Moreover, the practical application of this method was confirmed by an assay of Hg(II) in tap water samples with acceptable results.

Evaluation of harmful heavy metal (Hg, Pb and Cd reduction using Halomonas elongata and Tetragenococcus halophilusfor protein hydrolysate product

Directory of Open Access Journals (Sweden)

Ruttiya Asksonthon

2016-04-01

Full Text Available Background: Many health claims surrounding antioxidative, antihypertensive and anti-inflammatory properties have been addressed in natural protein hydrolysates, including fermented fish. Besides being sold as animal feed, tuna viscera is used for the production of fermented products like fish sauce and Tai pla, fermented viscera. However, toxic heavy metals including Hg, Pb and Cd have been found in various food items, particularly within the internal organs of tuna. Therefore, the consumption of fermented tuna viscera containing heavy metal involves health risks. Consequently, the detoxification and reduction of these toxic elements are relevant and important issues, particularly with the use of their bacterial cells and metabolic products. Halomonas elongatais a moderately halophilic bacterium which has the ability to remove heavy metal, and is normally found in hypersaline environments. Tetragenococcus halophilusis a moderately halophilic lactic acid bacterium and probiotic which is found in fermented food products, such as fish sauce, shrimp paste, and fermented fish. Some scientific studies have reported using T. halophilus improves amino acid profiles and desirable volatile compounds, in addition to reducing biogenic amine content in fish sauce product. Therefore, it was hypothesized that using H.elongata and T. halophilus could reduce heavy metal content and improve the organoleptic quality of fermented fish viscera product (Tai pla. Objective: This present work attempted to determine the growth characteristic of H. elongataand T. halophilus reared at various NaCl concentrations:10, 15, 20 and 25%. Consequently, heavy metal reduction using these microorganisms reared at optimum NaCl concentration was evaluated. Methods: H. elongate and T. halophilus were reared in saline nutrient broth (SNB and de Man, Rogosa and Sharpe (MRS-broth added with NaCl at concentration 10, 15, 20 and 25%, respectively. Cultures at each NaCl content were added

Graphical linking of MO multicenter bond index and VB structures. II-5-c rings and 6-c heterocyclic rings

International Nuclear Information System (INIS)

Bollini, Carlos Guido; Giambiagi, Mario; Giambiagi, Myriam Segre de; Figueiredo, Aloysio Paiva de

2001-02-01

Through the graphical method proposed it is possible to set a link between an MO multicenter bond index and VB structures. The value of the index depends on the order of the atoms involved if they are more than three. For 5-c rings three basic structures are required; the eventually different values are 12. Unlike the 6-c case it may happen that different pairs of basic structures are used to build the same polygon. For the 6-c rings including heteroatoms the original degeneracy of benzene splits leading eventually to 60 different I ring values. (author)

Preparation and use of chemically modified MCM-41 and silica gel as selective adsorbents for Hg(II) ions

International Nuclear Information System (INIS)

Puanngam, Mahitti; Unob, Fuangfa

2008-01-01

Adsorbents for Hg(II) ion extraction were prepared using amorphous silica gel and ordered MCM-41. Grafting with 2-(3-(2-aminoethylthio)propylthio)ethanamine was used to functionalize the silica. The functionalized adsorbents were characterized by nitrogen adsorption, X-ray diffraction, 13 C MAS NMR spectroscopy and thermogravimetric analysis. The adsorption properties of the modified silica gel and MCM-41 were compared using batch method. The effect of pH, stirring time, ionic strength and foreign ions were studied. The extraction of Hg(II) ions occurred rapidly with the modified MCM-41 and the optimal pH range for the extraction by the modified materials was pH 4-7. Foreign ions, especially Cl - had some effect on the extraction efficiency of the modified silica gel and the modified MCM-41. The adsorption behavior of both adsorbents could be described by a Langmuir model at 298 K, and the maximum adsorption capacity of the modified silica gel and MCM-41 at pH 3 was 0.79 and 0.70 mmol g -1 , respectively. The modified MCM-41 showed a larger Langmuir constant than that of the modified silica gel, indicating a better ability for Hg(II) ion adsorption. The results indicate that the structure of the materials affects the adsorption behavior. These materials show a potential for the application as effective and selective adsorbents for Hg(II) removal from water

Electric field gradient and electronic structure of linear-bonded halide compounds

International Nuclear Information System (INIS)

Ellis, D.E.; Guenzburger, D.J.R.; Jansen, H.B.

1983-01-01

The importance of covalent metal-ligand interactions in determining hyperfine fields and energy-level structure of MX 2 linear-bonded halide compounds has been studied, using the self-consistent local density molecular orbital approach. Results for FeCl 2 , FeBr 2 and EuCl 2 obtained using the Discrete Variational Method with numerical basis sets are presented. The high spin configuration for the iron compounds, first predicted by Berkowitz, et al., is verified; a successful comparison with gas phase photoelectron spectra is made. Variation of the predicted electric field gradient with bond length R is found to be rapid; the need for an EXAFS measurement of R for the matrix isolated species and experimental determination of the spin of the EFG is seen to be crucial for more accurate determinations of the sub(57) Fe quadrupole moment. (Author) [pt

Formation of an Ion-Pair Molecule with a Single NH+...Cl- Hydrogen Bond: Raman spectra of 1,1,3,3-Tetramethylguanidinium chloride in the solid state, in solution and in the vapor phase

DEFF Research Database (Denmark)

Berg, Rolf W.; Riisager, Anders; Fehrmann, Rasmus

2008-01-01

Some ionic compounds (salts) form liquids when heated to temperatures in the range of 200-300 °C. They may be referred to as moderate temperature ionic liquids. An example of such a compound is the 1,1,3,3- tetramethylguanidinium chloride, [TMGH]Cl, melting at ∼212 °C. The chemistry of this compo......Some ionic compounds (salts) form liquids when heated to temperatures in the range of 200-300 °C. They may be referred to as moderate temperature ionic liquids. An example of such a compound is the 1,1,3,3- tetramethylguanidinium chloride, [TMGH]Cl, melting at ∼212 °C. The chemistry...... and the dimeric chloride ion-pair salt converged to give geometries near the established crystal structure of [TMGH]Cl. The structures and their binding energies are given as well as calculated vibrational harmonic normal modes (IR and Raman band wavenumbers and intensities). Experimentally obtained Raman...... scattering spectra are presented and assigned, by comparing to the quantum mechanical calculations. It is concluded that dimeric molecular ion pairs with four N-H+ · · · Cl- hydrogen bonds probably exist in the solutions and are responsible for the relatively high solubility of the “salt” in ethanol...

Intracellular Hg(0) Oxidation in Desulfovibrio desulfuricans ND132.

Science.gov (United States)

Wang, Yuwei; Schaefer, Jeffra K; Mishra, Bhoopesh; Yee, Nathan

2016-10-03

The disposal of elemental mercury (Hg(0)) wastes in mining and manufacturing areas has caused serious soil and groundwater contamination issues. Under anoxic conditions, certain anaerobic bacteria can oxidize dissolved elemental mercury and convert the oxidized Hg to neurotoxic methylmercury. In this study, we conducted experiments with the Hg-methylating bacterium Desulfovibrio desulfuricans ND132 to elucidate the role of cellular thiols in anaerobic Hg(0) oxidation. The concentrations of cell-surface and intracellular thiols were measured, and specific fractions of D. desulfuricans ND132 were examined for Hg(0) oxidation activity and analyzed with extended X-ray absorption fine structure (EXAFS) spectroscopy. The experimental data indicate that intracellular thiol concentrations are approximately six times higher than those of the cell wall. Cells reacted with a thiol-blocking reagent were severely impaired in Hg(0) oxidation activity. Spheroplasts lacking cell walls rapidly oxidized Hg(0) to Hg(II), while cell wall fragments exhibited low reactivity toward Hg(0). EXAFS analysis of spheroplast samples revealed that multiple different forms of Hg-thiols are produced by the Hg(0) oxidation reaction and that the local coordination environment of the oxidized Hg changes with reaction time. The results of this study indicate that Hg(0) oxidation in D. desulfuricans ND132 is an intracellular process that occurs by reaction with thiol-containing molecules.

Luminescent turn-on detection of Hg(II) via the quenching of an iridium(III) complex by Hg(II)-mediated silver nanoparticles.

Science.gov (United States)

Liu, Jinshui; Vellaisamy, Kasipandi; Yang, Guanjun; Leung, Chung-Hang; Ma, Dik-Lung

2017-06-15

A novel luminescent turn-on detection method for Hg(II) was developed. The method was based on the silver nanoparticle (AgNP)-mediated quenching of Ir(III) complex 1. The addition of Hg(II) ions causes the luminescence of complex 1 to be recovered due to the oxidation of AgNPs by Hg(II) ions to form Ag(I) and Ag/Hg amalgam. The luminescence intensity of 1 increased in accord with an increased Hg(II) concentration ranging from 0 nM to 180 nM, with the detection limit of 5 nM. This approach offers an innovative method for the quantification of Hg(II).

Determining Bond Sodium Remaining in Plenum Region of Spent Nuclear Driver Fuel

International Nuclear Information System (INIS)

Vaden, D.; Li, S.X.

2008-01-01

The Fuel Conditioning Facility (FCF) at the Idaho National Laboratory (INL) treats spent nuclear fuel using an electro-chemical process that separates the uranium from the fission products, sodium thermal bond, and cladding materials (REF 1). Upon immersion into the ER electrolyte, the sodium used to thermally bond the fuel to the clad jacket chemically reacts with the UCl3 in the electrolyte producing NaCl and uranium metal. The uranium in the spent fuel is separated from the cladding and fission products by taking advantage of the electro-chemical potential differences between uranium and the other fuel components. Assuming all the sodium in the thermal bond is converted to NaCl in the ER, the difference between the cumulative bond sodium mass in the fuel elements and the cumulative sodium mass found in the driver ER electrolyte inventory provides an upper mass limit for the sodium that migrated to the upper gas region, or plenum section, of the fuel element during irradiation in the reactor. The plenums are to be processed as metal waste via melting and metal consolidation operations. However, depending on the amount of sodium in the plenums, additional processing may be required to remove the sodium before metal waste processing

40 CFR 60.4160 - Submission of Hg allowance transfers.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Submission of Hg allowance transfers... Times for Coal-Fired Electric Steam Generating Units Hg Allowance Transfers § 60.4160 Submission of Hg allowance transfers. An Hg authorized account representative seeking recordation of a Hg allowance transfer...

Multiple-scattering and DV-Xα analyses of a Cl-passivated Ge(111) surface

International Nuclear Information System (INIS)

Cao, S; Tang, J-C; Shen, S-L

2003-01-01

The multiple-scattering cluster and DV-Xα methods have been employed to analyse the chlorine 1s near edge x-ray absorption fine structure (NEXAFS) of a Cl-passivated Ge(111) surface. Our detailed analysis demonstrates how the chlorine atoms form a perfect monochloride structure with Cl bonding to the topmost Ge atom. Our calculation reveals the interaction in the chlorine layer is multipolar electrostatic forces. Furthermore, the DV-Xα cluster calculation shows that the orbital contour of the sharp Cl-Ge resonance exhibits a global symmetry, which confirms it to be σ * -like. The above studies are found to enrich previous experimental NEXAFS investigations

Structural and Biochemical Characterization of a Copper-Binding Mutant of the Organomercurial Lyase MerB: Insight into the Key Role of the Active Site Aspartic Acid in Hg-Carbon Bond Cleavage and Metal Binding Specificity.

Science.gov (United States)

Wahba, Haytham M; Lecoq, Lauriane; Stevenson, Michael; Mansour, Ahmed; Cappadocia, Laurent; Lafrance-Vanasse, Julien; Wilkinson, Kevin J; Sygusch, Jurgen; Wilcox, Dean E; Omichinski, James G

2016-02-23

In bacterial resistance to mercury, the organomercurial lyase (MerB) plays a key role in the detoxification pathway through its ability to cleave Hg-carbon bonds. Two cysteines (C96 and C159; Escherichia coli MerB numbering) and an aspartic acid (D99) have been identified as the key catalytic residues, and these three residues are conserved in all but four known MerB variants, where the aspartic acid is replaced with a serine. To understand the role of the active site serine, we characterized the structure and metal binding properties of an E. coli MerB mutant with a serine substituted for D99 (MerB D99S) as well as one of the native MerB variants containing a serine residue in the active site (Bacillus megaterium MerB2). Surprisingly, the MerB D99S protein copurified with a bound metal that was determined to be Cu(II) from UV-vis absorption, inductively coupled plasma mass spectrometry, nuclear magnetic resonance, and electron paramagnetic resonance studies. X-ray structural studies revealed that the Cu(II) is bound to the active site cysteine residues of MerB D99S, but that it is displaced following the addition of either an organomercurial substrate or an ionic mercury product. In contrast, the B. megaterium MerB2 protein does not copurify with copper, but the structure of the B. megaterium MerB2-Hg complex is highly similar to the structure of the MerB D99S-Hg complexes. These results demonstrate that the active site aspartic acid is crucial for both the enzymatic activity and metal binding specificity of MerB proteins and suggest a possible functional relationship between MerB and its only known structural homologue, the copper-binding protein NosL.

Hg uptake in ureteral obstructions

International Nuclear Information System (INIS)

Desgrez, J.P.; Bourguignon, M.; Raynaud, C.; CEA, 91 - Orsay

1976-01-01

In the presence of a total obstruction the results obtained with the Hg uptake test, as indeed with other functional tests, inform on the value of the kidney function at the time but have no prognostic value where repair possibilities are concerned. Some preliminary results seem to show however that very soon after the obstacle is removed, by the 10th or 15th day perhaps, quantitative functional tests may once more be used to evaluate the functional prognosis. This would mean that by waiting about two weeks after the disappearance of a total obstruction the Hg uptake test may again be used in all confidence. In order to check this deduction, which is based on slender evidence but which nevertheless has important practical implications, the measurement of the Hg uptake rate during the days following removal of the obstacle appears essential. In long-standing partial obstructions the Hg uptake rate gives an accurate assessment of the functional balance and helps considerably in the choice of therapy [fr

Formation of stable and metastable phases in reciprocal systems PbSe + MI2 = MSe + PbI2 (M = Hg, Mn, Sn)

International Nuclear Information System (INIS)

Odin, I.N.; Grin'ko, V.V.; Kozlovskij, V.F.; Safronov, E.V.; Gapanovich, M.V.

2004-01-01

Using data of differential thermal, X-ray phase and microstructural analyses, phase diagrams of reciprocal systems PbSe + MI 2 = MSe + PbI 2 (M=Hg (1), Mn (2), Sn (3)) were constructed. It was ascertained that the HgSe-PbI 2 diagonal in system 1 is stable. Transformations leading to crystallization of metastable ternary compound formed in the system PbSe-PbI 2 and metastable polytypes of lead iodide in systems 1 and 2 in the range of temperatures from 620 to 685 K were studied. New intermediate metastable phases in systems 1, 2 and 3 were prepared by melt quenching. Crystal lattice parameters of the phases crystallizing in the CdCl 2 structural type were defined [ru

Sedimentary mercury (Hg) in the marginal seas adjacent to Chinese high-Hg emissions: Source-to-sink, mass inventory, and accumulation history.

Science.gov (United States)

Kim, Jihun; Lim, Dhongil; Jung, Dohyun; Kang, Jeongwon; Jung, Hoisoo; Woo, Hanjun; Jeong, Kapsik; Xu, Zhaokai

2018-03-01

We comprehensively investigated sedimentary Hg in Yellow and East China Seas (YECSs), which constitute potentially important depocenters for large anthropogenic Hg emissions from mainland China. A large dataset of Al-TOC-Hg concentrations led to an in-depth understanding of sedimentary Hg in the entire YECSs, including distribution and its determinants, source-to-sink, background levels, inventory in flux and budget, and accumulation history. Especially, the net atmospheric Hg flux to the sediments was estimated to be 1.3 × 10 -5  g/m 2 /yr, which corresponded reasonably well to that calculated using a box model. About 21.2 tons of atmospheric Hg (approximately 4% of the total anthropogenic atmospheric Hg emissions from China) were buried annually in the YECS basin. This result implies that most of atmospheric Hg from China is transferred to the surface of the Pacific (including the East/Japan Sea and South China Sea) by the westerlies and, consequently, can play a critical role in open-sea aquatic ecosystems. Copyright © 2018 Elsevier Ltd. All rights reserved.

Experimental and theoretical studies of solvent effects on the hydrogen bonds in homoconjugated cations of substituted 4-halo (Cl, Br) pyridine N-oxide derivatives

International Nuclear Information System (INIS)

Gurzynski, Lukasz; Puszko, Aniela; Makowski, Mariusz; Chmurzynski, Lech

2007-01-01

Hydrogen bond OHO-type bridges formed between six substituted 4-halo (Cl, Br) pyridine N-oxide systems and their simple cations have been investigated by using the potentiometric titration method. The formation constants of these complexes (expressed as lgK BHB + ) have been determined in two non-aqueous aprotic solvents with different polarity, i.e., acetone (AC) and acetonitrile (AN). It has been observed that tri- and tetra-substituted pyridine N-oxides [B] and their cationic acids [BH + ] form stable homocomplexed cations [BHB + ] stabilized by O...H...O bridges in both solvents used. It has been found that the most stable homocomplexed system is formed by 3,5-dimethyl-4-chloropyridine N-oxide (3,5Me 2 4ClPyO). The lgK BHB + values for this compound in acetone and acetonitrile are 3.15 and 2.82, respectively. Furthermore, by using ab initio methods at the RHF and MP2 levels utilizing the Gaussian 6-31++G ** basis set, the energies of formation of the homocomplexed cations and Gibbs free energies have been determined in vacuo. The calculated energy parameters in vacuo have been compared with the cationic homoconjugation constants determined potentiometrically in acetone and acetonitrile to establish a correlation between these magnitudes. Additionally, the results of potentiometric measurements have been used to determine the acidity constants of the conjugate acids of N-oxides

Thiol-functionalization of metal-organic framework by a facile coordination-based postsynthetic strategy and enhanced removal of Hg2+ from water

International Nuclear Information System (INIS)

Ke, Fei; Qiu, Ling-Guang; Yuan, Yu-Peng; Peng, Fu-Min; Jiang, Xia; Xie, An-Jian; Shen, Yu-Hua; Zhu, Jun-Fa

2011-01-01

Highlights: ► A novel type of functionalized MOF for heavy metal removal. ► Functionalization of MOF by a facile coordination-based postsynthetic strategy. ► Thiol-functionalization of MOF has been realized for the first time. ► Enhanced removal of Hg 2+ by thiol-functionalized MOFs. - Abstract: The presence of coordinatively unsaturated metal centers in metal-organic frameworks (MOFs) provides an accessible way to selectively functionalize MOFs through coordination bonds. In this work, we describe thiol-functionalization of MOFs by choosing a well known three-dimensional (3D) Cu-based MOF, i.e. [Cu 3 (BTC) 2 (H 2 O) 3 ] n (HKUST-1, BTC = benzene-1,3,5-tricarboxylate), by a facile coordination-based postsynthetic strategy, and demonstrate their application for removal of heavy metal ion from water. A series of [Cu 3 (BTC) 2 ] n samples stoichiometrically decorated with thiol groups has been prepared through coordination bonding of coordinatively unsaturated metal centers in HKUST-1 with –SH group in dithioglycol. The obtained thiol-functionalized samples were characterized by powder X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscopy, infrared spectroscopy, and N 2 sorption–desorption isothermal. Significantly, the thiol-functionalized [Cu 3 (BTC) 2 ] n exhibited remarkably high adsorption affinity (K d = 4.73 × 10 5 mL g −1 ) and high adsorption capacity (714.29 mg g −1 ) for Hg 2+ adsorption from water, while the unfunctionalized HKUST-1 showed no adsorption of Hg 2+ under the same condition.

The Ru-NO bonding in nitrosyl-[poly(1-pyrazolyl)borate]ruthenium complexes: a theoretical insight based on EDA