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.

Formation and Characterization of Silver Nanoparticle Composite with Poly(p-Br/F-phenylsilane).

Science.gov (United States)

Roh, Sung-Hee; Noh, Ji Eun; Woo, Hee-Gweon; Cho, Myong-Shik; Sohn, Honglae

2015-02-01

The one-pot production and structural characterization of composites of silver nanoparticles with poly(p-Br/F-phenylsilane), Br/F-PPS, have been performed. The conversion of Ag+ ions to stable Ag0 nanoparticles is mediated by the copolymer Br/F-PPS having both possibly reactive Si-H bonds in the polymer backbone and C-Br bonds in the substituents along with relatively inert C-F bonds. Transmission electron microscopy and field emission scanning electron microscopy analyses show the formation of the composites where silver nanoparticles (less than 30 nm of size) are well dispersed over the Br/F-PPS matrix. X-ray diffraction patterns are consistent with that for face-centered-cubic typed silver. The polymer solubility in toluene implys that the cleavage of C-Br bond and the Si-F dative bonding may not be occurred appreciably at ambient temperature. Nonetheless, thermogravimetric analysis data suggest that some sort of cross-linking could take place at high temperature. Most of the silver particles undergo macroscopic aggregation without Br/F-PPS, which indicates that the polysilane is necessary for stabilizing the silver nanoparticles.

Synthesis and characterization of silver nanoparticle composite with poly(p-Br-phenylsilane).

Science.gov (United States)

Kim, Myoung-Hee; Lee, Jun; Mo, Soo-Yong; Woo, Hee-Gweon; Yang, Kap Seung; Kim, Bo-Hye; Lee, Byeong-Gweon; Sohn, Honglae

2012-05-01

The one-pot synthesis and characterization of silver nanoparticle-poly(p-Br-phenylsilane) composites have been carried out. The conversion of silver(+1) salt to stable silver(0) nanoparticles is promoted by poly(p-Br-phenylsilane), Br-PPS possessing both possible reactive Si-H bonds in the polymer backbone and C-Br bonds in the substituents. The composites were characterized using XRD, TEM, FE-SEM, and solid-state UV-vis analytical techniques. TEM and FE-SEM data show the formation of the composites where large number of silver nanoparticles (less than 30 nm of size) are well dispersed throughout the Br-PPS matrix. XRD patterns are consistent with that for fcc-typed silver. The elemental analysis for Br atom and the polymer solubility confirm that the cleavage of C-Br bond and the Si-Br dative bonding were not occurred appreciably at ambient temperature. Nonetheless, TGA data suggest that some sort of cross-linking was occurred at high temperature. The size and processability of such nanoparticles depend on the ratio of metal to Br-PPS. In the absence of Br-PPS, most of the silver particles undergo macroscopic aggregation, which indicates that the polysilane is necessary for stabilizing the silver nanoparticles.

INAA study of Hg, Se, As, and Br irradiation losses from l-cysteine treated and untreated reference materials

International Nuclear Information System (INIS)

Anderson, D.L.

2013-01-01

U. S. Food and Drug Administration in-house reference material (RM) Cocoa Powder and National Institute of Standards and Technology Standard RMs (SRMs) 1515 apple leaves, 1547 peach leaves, 1571 orchard leaves, 1566a oyster tissue, and 1568a rice flour were co-irradiated together with polyethylene blanks and analyzed for Hg and Se by anticoincidence instrumental neutron activation analysis. The three botanical SRM portions showed a combined Hg recovery of 70 % while the other portions showed a combined Hg recovery of 169 %, indicating that volatile Hg was lost from botanical SRMs and absorbed by the other irradiated portions. Total Hg recovery for all portions was 82 %. Se results showed no evidence of cross-contamination and all results agreed with certified and known values. National Research Council of Canada Certified RMs DOLT-3 dogfish liver, TORT-2 lobster hepatopancreas, and DORM-3 fish protein were separately analyzed either with no treatment or after treatment with l-cysteine solutions followed by drying over magnesium perchlorate. Each set of portions was co-irradiated with polyethylene and treated filter blanks. Analysis of all components of each treated portion irradiation package showed that essentially all Hg was retained within the package. Treated DOLT-3 portions (inorganic Hg content 53 %) showed a tenfold improvement with 99 % Hg retention. Hg retention for DORM-3 (7 % inorganic Hg) was 85 % (a twofold improvement) while retention for TORT-2 (44 % inorganic Hg), was 94 %, similar to that for untreated portions (96 %). Small irradiation losses (≤0.5 %) of volatile species of Se, As, and Br were observed. (author)

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.

Crystal structure, hydrogen bonding, and sup 8 sup 1 Br NQR of low-temperature phase of 4-aminopyridinium tetrabromoantimonate (3)

CERN Document Server

Hashimoto, M; Fuess, H; Svoboda, I; Ehrenberg, H

2003-01-01

The crystal structure of the low-temperature phase (LTP) of the title compound was determined at 220 K (monoclinic, P2 sub 1 sub / sub c). The 4-aminopyridinium cations (4-NH sub 2 C sub 5 H sub 4 NH sup +) were found to be ordered in LTP, while being severely disordered in the room-temperature phase (monoclinic, C2/c). The tetrabromoantimonate anions (SbBr sub 4 sup -) were incorporated into the infinite polyanion chains of irregular SbBr sub 6 octahedra with two-edges sharing. The trans-Br-Sb-Br moiety in the SbBr sub 4 sup - anion was approximately symmetric differing from the asymmetric Br-Sb centre dot centre dot centre dot Br moiety found in LTP of pyridinium tetrabromoantimonate (3). The N-H moieties in both of the pyridine ring and the amino (-NH sub 2) group participate in the formation of N-H centre dot centre dot centre dot Br hydrogen bonds. It was shown that the sup 8 sup 1 Br NQR spectrum of LTP is closely related to the anion structure and the hydrogen bonds. The distinctive anion structures, a...

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.

Carbon monoxide protonation in condensed phases and bonding to surface superacidic Brønsted centers.

Science.gov (United States)

Stoyanov, Evgenii S; Malykhin, Sergei E

2016-02-14

Using infrared (IR) spectroscopy and density functional theory (DFT) calculations, interaction of CO with the strongest known pure Brønsted carborane superacids, H(CHB11Hal11) (Hal = F, Cl), was studied. CO readily interacted at room temperature with H(CHB11F11) acid, forming a mixture of bulk salts of formyl and isoformyl cations, which were in equilibrium An(-)H(+)CO COH(+)An(-). The bonding of CO to the surface Brønsted centers of the weaker acid, H(CHB11Cl11), resulted in breaking of the bridged H-bonds of the acid polymers without proton transfer (PT) to CO. The binding occurred via the C atom (blue shift ΔνCO up to +155-167 cm(-1), without PT) or via O atom (red shift ΔνCO up to -110 cm(-1), without PT) always simultaneously, regardless of whether H(+) is transferred to CO. IR spectra of all species were interpreted by B3LYP/cc-pVQZ calculations of the simple models, which adequately mimic the ability of carborane acids to form LH(+)CO, LH(+)CO, COH(+)L, and COH(+)L compounds (L = bases). The CO bond in all compounds was triple. Acidic strength of the Brønsted centers of commonly used acid catalysts, even so-called superacidic catalysts, is not sufficient for the formation of the compounds studied.

Evidence for concerted ring opening and C-Br bond breaking in UV-excited bromocyclopropane.

Science.gov (United States)

Pandit, Shubhrangshu; Preston, Thomas J; King, Simon J; Vallance, Claire; Orr-Ewing, Andrew J

2016-06-28

Photodissociation of gaseous bromocyclopropane via its A-band continuum has been studied at excitation wavelengths ranging from 230 nm to 267 nm. Velocity-map images of ground-state bromine atoms (Br), spin-orbit excited bromine atoms (Br(∗)), and C3H5 hydrocarbon radicals reveal the kinetic energies of these various photofragments. Both Br and Br(∗) atoms are predominantly generated via repulsive excited electronic states in a prompt photodissociation process in which the hydrocarbon co-fragment is a cyclopropyl radical. However, the images obtained at the mass of the hydrocarbon radical fragment identify a channel with total kinetic energy greater than that deduced from the Br and Br(∗) images, and with a kinetic energy distribution that exceeds the energetic limit for Br + cyclopropyl radical products. The velocity-map images of these C3H5 fragments have lower angular anisotropies than measured for Br and Br(∗), indicating molecular restructuring during dissociation. The high kinetic energy C3H5 signals are assigned to allyl radicals generated by a minor photochemical pathway which involves concerted C-Br bond dissociation and cyclopropyl ring-opening following single ultraviolet (UV)-photon absorption. Slow photofragments also contribute to the velocity map images obtained at the C3H5 radical mass, but the corresponding slow Br atoms are not observed. These features in the images are attributed to C3H5 (+) from the photodissociation of the C3H5Br(+) molecular cation following two-photon ionization of the parent compound. This assignment is confirmed by 118-nm vacuum ultraviolet ionization studies that prepare the molecular cation in its ground electronic state prior to UV photodissociation.

Nonadiabatic effects in C-Br bond scission in the photodissociation of bromoacetyl chloride

International Nuclear Information System (INIS)

Valero, Rosendo; Truhlar, Donald G.

2006-01-01

Bromoacetyl chloride photodissociation has been interpreted as a paradigmatic example of a process in which nonadiabatic effects play a major role. In molecular beam experiments by Butler and co-workers [J. Chem. Phys. 95, 3848 (1991); J. Chem. Phys. 97, 355 (1992)], BrCH 2 C(O)Cl was prepared in its ground electronic state (S 0 ) and excited with a laser at 248 nm to its first excited singlet state (S 1 ). The two main ensuing photoreactions are the ruptures of the C-Cl bond and of the C-Br bond. A nonadiabatic model was proposed in which the C-Br scission is strongly suppressed due to nonadiabatic recrossing at the barrier formed by the avoided crossing between the S 1 and S 2 states. Recent reduced-dimensional dynamical studies lend support to this model. However, another interpretation that has been given for the experimental results is that the reduced probability of C-Br scission is a consequence of incomplete intramolecular energy redistribution. To provide further insight into this problem, we have studied the energetically lowest six singlet electronic states of bromoacetyl chloride by using an ab initio multiconfigurational perturbative electronic structure method. Stationary points (minima and saddle points) and minimum energy paths have been characterized on the S 0 and S 1 potential energy surfaces. The fourfold way diabatization method has been applied to transform five adiabatic excited electronic states to a diabatic representation. The diabatic potential energy matrix of the first five excited singlet states has been constructed along several cuts of the potential energy hypersurfaces. The thermochemistry of the photodissociation reactions and a comparison with experimental translational energy distributions strongly suggest that nonadiabatic effects dominate the C-Br scission, but that the reaction proceeds along the energetically allowed diabatic pathway to excited-state products instead of being nonadiabatically suppressed. This conclusion is

UiO-66 and its Br-modified derivates for elemental mercury removal.

Science.gov (United States)

Zhang, Xiao; Shen, Boxiong; Zhu, Sheaowen; Xu, Huan; Tian, Linghui

2016-12-15

Phenyl bromine-appended metal-organic frameworks (Br-MOFs) were synthesized and applied in elemental mercury (Hg 0 ) removal from simulated flue gas, considering the stability of bromine on the materials at the same time. The techniques of PXRD, nitrogen adsorption, TGA and XPS were used to characterize the materials. Phenyl bromide on the MOFs was the main active site for Hg 0 capture. The optimal Br-MOF showed high Hg 0 removal efficiency of more than 99% for 48h at 200°C, whereas the efficiency of un-functionalized MOF and conventional bromine impregnated active carbon dropped to 59.8% and 91.2% within 5h, respectively. The crystalline integrity of the Br-MOF was maintained after Hg 0 adsorption. Br-MOF exhibited enhanced Hg 0 removal efficiency when SO 2 was introduced to the flue gas. However, exposure Br-MOF to flue gas with steam resulted in low Hg 0 removal efficiency. Bromine leaching experiments proved that Br-MOFs have high bromine stability over the Hg 0 adsorption process, avoiding the possible bromine pollution caused by the conventional bromine impregnated adsorbents. All of these results demonstrated the phenyl bromine-appended MOFs to be potential Hg 0 adsorbent regarding its high Hg 0 capture efficiency and low environmental risk. Copyright © 2016. Published by Elsevier B.V.

Evidence for concerted ring opening and C–Br bond breaking in UV-excited bromocyclopropane

Energy Technology Data Exchange (ETDEWEB)

Pandit, Shubhrangshu; Preston, Thomas J.; Orr-Ewing, Andrew J., E-mail: a.orr-ewing@bristol.ac.uk [School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS (United Kingdom); King, Simon J.; Vallance, Claire [Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA (United Kingdom)

2016-06-28

Photodissociation of gaseous bromocyclopropane via its A-band continuum has been studied at excitation wavelengths ranging from 230 nm to 267 nm. Velocity-map images of ground-state bromine atoms (Br), spin-orbit excited bromine atoms (Br{sup ∗}), and C{sub 3}H{sub 5} hydrocarbon radicals reveal the kinetic energies of these various photofragments. Both Br and Br{sup ∗} atoms are predominantly generated via repulsive excited electronic states in a prompt photodissociation process in which the hydrocarbon co-fragment is a cyclopropyl radical. However, the images obtained at the mass of the hydrocarbon radical fragment identify a channel with total kinetic energy greater than that deduced from the Br and Br{sup ∗} images, and with a kinetic energy distribution that exceeds the energetic limit for Br + cyclopropyl radical products. The velocity-map images of these C{sub 3}H{sub 5} fragments have lower angular anisotropies than measured for Br and Br{sup ∗}, indicating molecular restructuring during dissociation. The high kinetic energy C{sub 3}H{sub 5} signals are assigned to allyl radicals generated by a minor photochemical pathway which involves concerted C–Br bond dissociation and cyclopropyl ring-opening following single ultraviolet (UV)-photon absorption. Slow photofragments also contribute to the velocity map images obtained at the C{sub 3}H{sub 5} radical mass, but the corresponding slow Br atoms are not observed. These features in the images are attributed to C{sub 3}H{sub 5}{sup +} from the photodissociation of the C{sub 3}H{sub 5}Br{sup +} molecular cation following two-photon ionization of the parent compound. This assignment is confirmed by 118-nm vacuum ultraviolet ionization studies that prepare the molecular cation in its ground electronic state prior to UV photodissociation.

Synthesis and structure of [(NH2)2CSSC(NH2)2]2[OsBr6]Br2 . 3H2O

International Nuclear Information System (INIS)

Rudnitskaya, O. V.; Kultyshkina, E. K.; Stash, A. I.; Glukhova, A. A.; Venskovskii, N. U.

2008-01-01

The complex [(NH 2 ) 2 CSSC(NH 2 ) 2 ] 2 [OsBr 6 ]Br 2 . 3H 2 O is synthesized by the reaction of K 2 OsBr 6 with thiocarbamide in concentrated HBr and characterized using electronic absorption and IR absorption spectroscopy. Its crystal structure is determined by X-ray diffraction. The crystals are orthorhombic, a = 11.730(2) A, b = 14.052(3) A, c = 16.994(3) A, space group Cmcm, and Z = 4. The [OsBr 6 ] 2- anionic complex has an octahedral structure. The Os-Br distances fall in the range 2.483-2.490 A. The α,α'-dithiobisformamidinium cation is a product of the oxidation of thiocarbamide. The S-S and C-S distances are 2.016 and 1.784 A, respectively. The H 2 O molecules, Br - ions, and NH 2 groups of the cation are linked by hydrogen bonds.

New results for the formation of a muoniated radical in the Mu + Br2 system: a van der Waals complex or evidence for vibrational bonding in Br-Mu-Br?

Science.gov (United States)

Fleming, Donald G; Cottrell, Stephen P; McKenzie, Iain; Macrae, Roderick M

2012-08-21

New evidence is presented for the observation of a muoniated radical in the Mu + Br(2) system, from μSR longitudinal field (LF) repolarisation studies in the gas phase, at Br(2) concentrations of 0.1 bar in a Br(2)/N(2) mixture at 300 K and at 10 bar total pressure. The LF repolarisation curve, up to a field of 4.5 kG, reveals two paramagnetic components, one for the Mu atom, formed promptly during the slowing-down process of the positive muon, with a known Mu hyperfine coupling constant (hfcc) of 4463 MHz, and one for a muoniated radical formed by fast Mu addition. From model fits to the Br(2)/N(2) data, the radical component is found to have an unusually high muon hfcc, assessed to be ∼3300 MHz with an overall error due to systematics expected to exceed 10%. This high muon hfcc is taken as evidence for the observation of either the Br-Mu-Br radical, and hence of vibrational bonding in this H[combining low line]-L[combining low line]-H[combining low line] system, or of a MuBr(2) van der Waals complex formed in the entrance channel. Preliminary ab initio electronic structure calculations suggest the latter is more likely but fully rigorous calculations of the effect of dynamics on the hfcc for either system have yet to be carried out.

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

Satellite Observations of Tropospheric BrO over Salt Lakes and Northern High Latitudes from EOS/OMI and SNPP/OMPS

Science.gov (United States)

Kurosu, T. P.; Stutz, J.; Brockway, N.; Saiz-Lopez, A.; Suleiman, R. M.; Natraj, V.; Jaross, G.; Seftor, C. J.

2017-12-01

We present observations of tropospheric bromine monoxide (BrO) derived from two satellite instruments: the Ozone Monitoring Instrument (OMI) on EOS-Aura, and the Nadir Mapper component of the Ozone Mapping and Profiler Suite (OMPS) on Suomi/NPP. BrO observations from OMPS constitute a new and experimental measurement that we first report on here and compare with the standard BrO data product from OMI. BrO is a halogen oxide present mostly in the lower stratosphere, where it catalytically destroys ozone with about 25 times the efficiency of ClO. BrO also has a tropospheric component, where it is released from sea surfaces, at the interface of ocean water and sea ice in the polar spring, in volcanic plumes, and in the vicinity of salt lakes. Tropospheric BrO has been linked to mercury (Hg) deposition through BrO-induced conversion of gaseous Hg to reactive Hg, which is then deposited on the surface and enters the food chain, ultimately affecting human health. As part of NASA's Aura Science Team, we are developing an OMI Tropospheric BrO data product that provides a unique global data set on BrO spatial and vertical distribution in the troposphere and stratosphere. Information of this kind is currently unavailable from any of the past and present bromine-monitoring instruments. In this presentation, we focus on multi-year time series of BrO released from a range of salt lakes - the Rann of Kutch, Salar de Uyuni, the Aral Sea, and others. We quantify the amount of bromine released from the lakes and investigate the possibility of lake desiccation monitoring based on independent BrO observations. The quality and limits of OMI and OMPS tropospheric BrO observations is investigated by comparison with ground-based MAX-DOAS observations over central Greenland.

New Type of Halogen Bond: Multivalent Halogen Interacting with π- and σ-Electrons

Directory of Open Access Journals (Sweden)

Sławomir J. Grabowski

2017-12-01

Full Text Available MP2/aug-cc-pVTZ calculations were performed for complexes of BrF3 and BrF5 acting as Lewis acids through the bromine centre, with species playing a role of Lewis base: dihydrogen, acetylene, ethylene, and benzene. The molecular hydrogen donates electrons by its σ-bond, while in remaining moieties—in complexes of hydrocarbons; such an electron transfer follows from π-electrons. The complexes are linked by a kind of the halogen bond that is analyzed for the first time in this study, i.e., it is the link between the multivalent halogen and π or σ-electrons. The nature of such a halogen bond is discussed, as well as various dependencies and correlations are presented. Different approaches are applied here, the Quantum Theory of Atoms in Molecules, Natural Bond Orbital method, the decomposition of the energy of interaction, the analysis of electrostatic potentials, etc.

Br2 elimination in 248-nm photolysis of CF2Br2 probed by using cavity ring-down absorption spectroscopy.

Science.gov (United States)

Hsu, Ching-Yi; Huang, Hong-Yi; Lin, King-Chuen

2005-10-01

By using cavity ring-down absorption spectroscopy technique, we have observed the channel of Br2 molecular elimination following photodissociation of CF2Br2 at 248 nm. A tunable laser beam, which is crossed perpendicular to the photolyzing laser beam in a ring-down cell, is used to probe the Br2 fragment in the B 3Piou+-X1Sigmag+ transition. The vibrational population is obtained in a nascent state, despite ring-down time as long as 500-1000 ns. The population ratio of Br2(v=1)/Br2(v=0) is determined to be 0.4+/-0.2, slightly larger than the value of 0.22 evaluated by Boltzmann distribution at room temperature. The quantum yield of the Br2 elimination reaction is also measured to be 0.04+/-0.01. This work provides direct evidence to support molecular elimination occurring in the CF2Br2 photodissociation and proposes a plausible pathway with the aid of ab initio potential-energy calculations. CF2Br2 is excited probably to the 1B1 and 3B2 states at 248 nm. As the C-Br bond is elongated upon excitation, the coupling of the 1A'(1B1) state to the high vibrational levels of the ground state X 1A'(1A1) may be enhanced to facilitate the process of internal conversion. After transition, the highly vibrationally excited CF2Br2 feasibly surpasses a transition barrier prior to decomposition. According to the ab initio calculations, the transition state structure tends to correlate with the intermediate state CF2Br+Br(CF2Br...Br) and the products CF2+Br2. A sequential photodissociation pathway is thus favored. That is, a single C-Br bond breaks, and then the free-Br atom moves to form a Br-Br bond, followed by the Br2 elimination. The formed Br-Br bond distance in the transition state tends to approach equilibrium such that the Br2 fragment may be populated in cold vibrational distribution. Observation of a small vibrational population ratio of Br2(v=1)Br2(v=0) agrees with the proposed mechanism.

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.

Dicty_cDB: FC-BR21 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available FC (Link to library) FC-BR21 (Link to dictyBase) - - - Contig-U15384-1 | Contig-U16443-1 FC-BR2...1P (Link to Original site) FC-BR21F 551 FC-BR21Z 122 FC-BR21P 673 - - Show FC-BR21 Library FC (L...ink to library) Clone ID FC-BR21 (Link to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Cont...ig-U15384-1 | Contig-U16443-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-BR/FC-BR2...1Q.Seq.d/ Representative seq. ID FC-BR21P (Link to Original site) Representative DNA sequence >FC-BR21 (FC-BR2

Density Functional Study of Structures and Electron Affinities of BrO4F/BrO4F-

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Wei Li

2009-07-01

Full Text Available The structures, electron affinities and bond dissociation energies of BrO4F/BrO4F− species have been investigated with five density functional theory (DFT methods with DZP++ basis sets. The planar F-Br…O2…O2 complexes possess 3A' electronic state for neutral molecule and 4A' state for the corresponding anion. Three types of the neutral-anion energy separations are the adiabatic electron affinity (EAad, the vertical electron affinity (EAvert, and the vertical detachment energy (VDE. The EAad value predicted by B3LYP method is 4.52 eV. The bond dissociation energies De (BrO4F → BrO4-mF + Om (m = 1-4 and De- (BrO4F- → BrO4-mF- + Om and BrO4F- → BrO4-mF + Om- are predicted. The adiabatic electron affinities (EAad were predicted to be 4.52 eV for F-Br…O2…O2 (3A'← 4A' (B3LYP method.

Dicty_cDB: FC-BR23 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available FC (Link to library) FC-BR23 (Link to dictyBase) - - - Contig-U15008-1 FC-BR23Z (Li...nk to Original site) - - FC-BR23Z 641 - - - - Show FC-BR23 Library FC (Link to library) Clone ID FC-BR23 (Li.../dictycdb.biol.tsukuba.ac.jp/CSM/FC/FC-BR/FC-BR23Q.Seq.d/ Representative seq. ID FC-BR2...3Z (Link to Original site) Representative DNA sequence >FC-BR23 (FC-BR23Q) /CSM/FC/FC-BR/FC-BR23Q.Seq....9 0.0 SLA211 (SLA211Q) /CSM/SL/SLA2-A/SLA211Q.Seq.d/ 1029 0.0 FC-BR23 (FC-BR23Q) /CSM/FC/FC-BR/FC-BR2

1-(Bromomercurioferrocene

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Jens M. Breunig

2014-01-01

Full Text Available The asymmetric unit of the title compound, [Fe(C5H5(C5H4BrHg], contains two independent molecules, A and B, in which the Hg—C bond lengths are 2.045 (6 and 2.046 (6 Å, the Hg—Br bond lengths are 2.4511 (9 and 2.4562 (7 Å, and the C—Hg—Br angles are 176.42 (17 and 177.32 (17°. The two cyclopentadienyl rings of molecule A are eclipsed, while those of molecule B are almost staggered. The HgBr groups are connected by intermolecular Hg...Br contacts of 3.3142 (9–3.4895 (11 Å, forming layers parallel to (001. These layers contain both four-membered (HgBr2 and eight-membered (HgBr4 rings. Ferrocene–ferrocene C—H...π contacts connect the molecular layers along the c-axis direction.

A novel hydrogen-bonded cyclic dibromide in an organic ...

Indian Academy of Sciences (India)

Unknown

2Institut für Anorganische Chemie, Christian-Albrechts-Universität Kiel, Olshausenstraße 40, D-24098 ... H2O molecules are linked to bromide anions via O–H⋅⋅⋅Br hydrogen bonding ..... Weiss R, Reichel S, Handlke M and Hampel F 1998.

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.

"Vibrational bonding": a new type of chemical bond is discovered.

Science.gov (United States)

Rhodes, Christopher J; Macrae, Roderick M

2015-01-01

A long-sought but elusive new type of chemical bond, occurring on a minimum-free, purely repulsive potential energy surface, has recently been convincingly shown to be possible on the basis of high-level quantum-chemical calculations. This type of bond, termed a vibrational bond, forms because the total energy, including the dynamical energy of the nuclei, is lower than the total energy of the dissociated products, including their vibrational zero-point energy. For this to be the case, the ZPE of the product molecule must be very high, which is ensured by replacing a conventional hydrogen atom with its light isotope muonium (Mu, mass = 1/9 u) in the system Br-H-Br, a natural transition state in the reaction between Br and HBr. A paramagnetic species observed in the reaction Mu +Br2 has been proposed as a first experimental sighting of this species, but definitive identification remains challenging.

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.

Interfering elements in activation analysis. Study of instrumental analysis possibilities for the groups: Sc-Zn, Hg-Se and As-Sb-Br

International Nuclear Information System (INIS)

Figueiredo, A.M.G.; Atalla, L.T.

1979-01-01

The determination of the elements present in the groups Sc-Zn, Hg-Se and As-Sb-Br represents a classical problem in thermal neutron activation analysis, since the energy values of the gamma-ray photopeaks of the radioisotopes of these elements formed by thermal neutron activation are very closely located in the spectrum. A study is presented of the possibility of simultaneous instrumental determination of these elements by means of the spectrum stripping technique. For this purpose, artificial mixtures of the interfering elements, in varying proportions, were prepared. Radiochemical separations procedures for the above mentioned elements were also studied by means of tracers. (Author) [pt

Cd4As2Br3

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Mohammed Kars

2014-03-01

Full Text Available Single crystals of Cd4As2Br3 (tetracadmium biarsenide tribromide were grown by a chemical transport reaction. The structure is isotypic with the members of the cadmium and mercury pnictidohalides family with general formula M4A2X3 (M = Cd, Hg; A = P, As, Sb; X = Cl, Br, I and contains two independent As atoms on special positions with site symmetry -3 and two independent Cd atoms, of which one is on a special position with site symmetry -3. The Cd4As2Br3 structure consists of AsCd4 tetrahedra sharing vertices with isolated As2Cd6 octahedra that contain As–As dumbbells in the centre of the octahedron. The Br atoms are located in the voids of this three-dimensional arrangement and bridge the different polyhedra through Cd...Br contacts.

Dye adsorbates BrPDI, BrGly, and BrAsp on anatase TiO2(001) for dye-sensitized solar cell applications

Science.gov (United States)

Çakır, D.; Gülseren, O.; Mete, E.; Ellialtıoǧlu, Ş.

2009-07-01

Using the first-principles plane-wave pseudopotential method within density functional theory, we systematically investigated the interaction of perylenediimide (PDI)-based dye compounds (BrPDI, BrGly, and BrAsp) with both unreconstructed (UR) and reconstructed (RC) anatase TiO2(001) surfaces. All dye molecules form strong chemical bonds with surface in the most favorable adsorption structures. In UR-BrGly, RC-BrGly, and RC-BrAsp cases, we have observed that highest occupied molecular orbital and lowest unoccupied molecular orbital levels of molecules appear within band gap and conduction-band region, respectively. Moreover, we have obtained a gap narrowing upon adsorption of BrPDI on the RC surface. Because of the reduction in effective band gap of surface-dye system and possibly achieving the visible-light activity, these results are valuable for photovoltaic and photocatalytic applications. We have also considered the effects of hydration of surface to the binding of BrPDI. It has been found that the binding energy drops significantly for the completely hydrated surfaces.

Adsorption of Hg on lunar samples

International Nuclear Information System (INIS)

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

1985-01-01

Understanding the presence, migration mechanisms and trapping of indigneous gases and volatiles on the moon is the objective of this study. The rare gases Ar and Xe and highly volatile Hg 0 and Br 0 (and/or their compounds) have been determined to be present in the lunar regolith. Evidence for these elements in the moon was recently reviewed. Studies of the sorption behavior of Xe on lunar material have been carried out. We report here preliminary results of a study designed to rationalize the behavior of Hg in lunar material

Enhanced interfacial radiation-induced reaction for improving the interfacial adhesion of incompatible polymer blend PP/BR

International Nuclear Information System (INIS)

Liu Changhai; Yang Huili; Xu Jun

1995-01-01

γ-radiation induced interfacial changes of incompatible polymer isotactic polypropylene (PP) and cis1,4-polybutadiene (BR) blends containing polyfunctional monomer (PFM) triallyl isocyanurate (TAIC) were investigated. The results of the study are as following: PP is incompatible with BR; TAIC is hardly dissolved in both PP and BR; when blended with PP/BR, the concentration of TAIC in the interfacial region is higher than that in dispersion phase of BR or matrix of PP. The crosslinking and/or grafting of which TAIC occurred under radiation in the interfacial region anchored the dispersed BR phase to PP matrix. The interaction between adjacent phases is changed from sole van der Waals force to co-action of both chemical bond and molecular forces. Crosslinking between adjacent phases links the dispersed phase with PP matrix, and grafting in the boundary regions increases the thickness of interface. These result in a good interfacial adhesion between dispersed phase and matrix. (author)

Partial structures in molten AgBr

Energy Technology Data Exchange (ETDEWEB)

Ueno, Hiroki [Department of Condensed Matter Chemistry and Physics, Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Chuo-ku, Fukuoka 810-8560 (Japan)], E-mail: ueno@gemini.rc.kyushu-u.ac.jp; Tahara, Shuta [Faculty of Pharmacy, Niigata University of Pharmacy and Applied Life Science, Higashijima, Akiha-ku, Niigata 956-8603 (Japan); Kawakita, Yukinobu [Department of Physics, Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Chuo-ku, Fukuoka 810-8560 (Japan); Kohara, Shinji [Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Takeda, Shin' ichi [Department of Physics, Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Chuo-ku, Fukuoka 810-8560 (Japan)

2009-02-21

The structure of molten AgBr has been studied by means of neutron and X-ray diffractions with the aid of structural modeling. It is confirmed that the Ag-Ag correlation has a small but well-defined first peak in the partial pair distribution function whose tail penetrates into the Ag-Br nearest neighbor distribution. This feature on the Ag-Ag correlation is intermediate between that of molten AgCl (non-superionic melt) and that of molten AgI (superionic melt). The analysis of Br-Ag-Br bond angle reveals that molten AgBr preserves a rocksalt type local ordering in the solid phase, suggesting that molten AgBr is clarified as non-superionic melt like molten AgCl.

Mechanisms for the reactions of group 10 transition metal complexes with metal-group 14 element bonds, Bbt(Br)E═M(PCy3)2 (E = C, Si, Ge, Sn, Pb; M = Pd and Pt).

Science.gov (United States)

Liao, Wei-Hung; Ho, Pei-Yun; Su, Ming-Der

2013-02-04

The electronic structures of the Bbt(Br)E═M(PCy(3))(2) (E = C, Si, Ge, Sn, Pb and M = Pt, Pd) complexes and their potential energy surfaces for the formation and water addition reactions were studied using density functional theory (B3LYP/LANL2DZ). The theoretical evidence suggests that the bonding character of the E═M double bond between the six valence-electron Bbt(Br)E: species and the 14 valence-electron (PCy(3))(2)M complexes has a predominantly high s-character. That is, on the basis of the NBO, this theoretical study indicates that the σ-donation from the E element to the M atom prevails. Also, theoretical computations suggest that the relative reactivity decreases in the order: Bbt(Br)C═M(PCy(3))(2) > Bbt(Br)Si═M(PCy(3))(2) > Bbt(Br)Ge═M(PCy(3))(2) > Bbt(Br)Sn═M(PCy(3))(2) > Bbt(Br)Pb═M(PCy(3))(2), irrespective of whether M = Pt or M = Pd is chosen. Namely, the greater the atomic weight of the group 14 atom (E), the larger is the atomic radius of E and the more stable is its Bbt(Br)E═M(PCy(3))(2) doubly bonded species toward chemical reactions. The computational results show good agreement with the available experimental observations. The theoretical results obtained in this work allow a number of predictions to be made.

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

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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.

Electric field gradients in Hg compounds

DEFF Research Database (Denmark)

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

2012-01-01

&H functional performs best at both 4-component and ZORA levels. We furthermore observe that changes in the largest component of the diagonalised EFG tensor, Vzz, of linear HgCl2 show a slightly stronger dependence than the r-3 scaling upon bond length r(Hg-Cl) alterations. The 4-component/BH&H Vzz value of -9.......26 a.u. for a bent HgCl2 (¿ Cl-Hg-Cl = 120¿) is close to -9.60 a.u. obtained for the linear HgCl2 structure. Thus a point charge model for EFG calculations completely fails in this case. By means of a projection analysis of molecular orbital (MO) contributions to Vzz in terms of the atomic constituents...

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

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).

A comparative ab initio study of Br2*- and Br2 water clusters.

Science.gov (United States)

Pathak, A K; Mukherjee, T; Maity, D K

2006-01-14

The work presents ab initio results on structure and electronic properties of Br2*-.nH2O(n=1-10) and Br2.nH2O(n=1-8) hydrated clusters to study the effects of an excess electron on the microhydration of the halide dimer. A nonlocal density functional, namely, Becke's half-and-half hybrid exchange-correlation functional is found to perform well on the present systems with a split valence 6-31++G(d,p) basis function. Geometry optimizations for all the clusters are carried out with several initial guess structures and without imposing any symmetry restriction. Br2*-.nH2O clusters prefer to have symmetrical double hydrogen-bonding structures. Results on Br2.nH2O(n>or=2) cluster show that the O atom of one H2O is oriented towards one Br atom and the H atom of another H2O is directed to other Br atom making Br2 to exist as Br+-Br- entity in the cluster. The binding and solvation energies are calculated for the Br2*-.nH2O and Br2.nH2O clusters. Calculations of the vibrational frequencies show that the formation of Br2*- and Br2 water clusters induces significant shifts from the normal modes of isolated water. Excited-state calculations are carried out on Br2*-.nH2O clusters following configuration interaction with single electron excitation procedure and UV-VIS absorption profiles are simulated. There is an excellent agreement between the present theoretical UV-VIS spectra of Br2*-.10H2O cluster and the reported transient optical spectra for Br2*- in aqueous solution.

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

Spectroscopic fingerprints for charge localization in the organic semiconductor (DOEO)4[HgBr4]·TCE

Science.gov (United States)

Koplak, Oksana V.; Chernenkaya, Alisa; Medjanik, Katerina; Brambilla, Alberto; Gloskovskii, Andrei; Calloni, Alberto; Elmers, Hans-Joachim; Schönhense, Gerd; Ciccacci, Franco; Morgunov, Roman B.

2015-05-01

Changes of the electronic structure accompanied by charge localization and a transition to an antiferromagnetic ground state were observed in the organic semiconductor (DOEO)4[HgBr4]·TCE. Localization starts in the temperature region of about 150 K and the antiferromagnetic state occurs below 60 K. The magnetic moment of the crystal contains contributions of inclusions (droplets), and individual paramagnetic centers formed by localized holes and free charge carriers at 2 K. Two types of inclusions of 100-400 nm and 2-5 nm sizes were revealed by transmission electron microscopy. Studying the temperature- and angular dependence of electron spin resonance (ESR) spectra revealed fingerprints of antiferromagnetic contributions as well as paramagnetic resonance spectra of individual localized charge carriers. The results point on coexistence of antiferromagnetic long and short range order as evident from a second ESR line. Photoelectron spectroscopy in the VUV, soft and hard X-ray range shows temperature-dependent effects upon crossing the critical temperatures around 60 K and 150 K. The substantially different probing depths of soft and hard X-ray photoelectron spectroscopy yield information on the surface termination. The combined investigation using complementary methods at the same sample reveals the close relation of changes in the transport properties and in the energy distribution of electronic states.

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.

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.

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

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.

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.

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.

Computations on the primary photoreaction of Br2 with CO2: stepwise vs concerted addition of Br atoms.

Science.gov (United States)

Xu, Kewei; Korter, Timothy M; Braiman, Mark S

2015-04-09

It was proposed previously that Br2-sensitized photolysis of liquid CO2 proceeds through a metastable primary photoproduct, CO2Br2. Possible mechanisms for such a photoreaction are explored here computationally. First, it is shown that the CO2Br radical is not stable in any geometry. This rules out a free-radical mechanism, for example, photochemical splitting of Br2 followed by stepwise addition of Br atoms to CO2-which in turn accounts for the lack of previously observed Br2+CO2 photochemistry in gas phases. A possible alternative mechanism in liquid phase is formation of a weakly bound CO2:Br2 complex, followed by concerted photoaddition of Br2. This hypothesis is suggested by the previously published spectroscopic detection of a binary CO2:Br2 complex in the supersonically cooled gas phase. We compute a global binding-energy minimum of -6.2 kJ mol(-1) for such complexes, in a linear geometry. Two additional local minima were computed for perpendicular (C2v) and nearly parallel asymmetric planar geometries, both with binding energies near -5.4 kJ mol(-1). In these two latter geometries, C-Br and O-Br bond distances are simultaneously in the range of 3.5-3.8 Å, that is, perhaps suitable for a concerted photoaddition under the temperature and pressure conditions where Br2 + CO2 photochemistry has been observed.

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.

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.

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

X-ray and NQR studies of bromoindate(III) complexes. [C2H5NH3]4InBr7, [C(NH2)3]3InBr6, and [H3NCH2C(CH3)2CH2NH3]InBr5

International Nuclear Information System (INIS)

Iwakiri, Takeharu; Ishihara, Hideta; Terao, Hiromitsu; Lork, Enno; Gesing, Thorsten M.

2017-01-01

The crystal structures of [C 2 H 5 NH 3 ] 4 InBr 7 (1), [C(NH 2 ) 3 ] 3 InBr 6 (2), and [H 3 NCH 2 C(CH 3 ) 2 CH 2 NH 3 ]InBr 5 (3) were determined at 100(2) K: monoclinic, P2 1 /n, a=1061.94(3), b=1186.40(4), c=2007.88(7) pm, β= 104.575(1) , Z=4 for 1; monoclinic, C2/c, a=3128.81(12), b=878.42(3), c=2816.50(10) pm, β=92.1320(10) , Z=16 for 2; orthorhombic, P2 1 2 1 2 1 , a=1250.33(5), b=1391.46(6), c=2503.22(9) pm, Z=4 for 3. The structure of 1 contains an isolated octahedral [InBr 6 ] 3- ion and a Br - ion. The structure of 2 contains three different isolated octahedral [InBr 6 ] 3- ions. The structure of 3 has a corner-shared double-octahedral [In 2 Br 11 ] 5- ion and an isolated tetrahedral [InBr 4 ] - ion. The 81 Br nuclear quadrupole resonance (NQR) lines of the terminal Br atoms of the compounds are widely spread in frequency, and some of them show unusual positive temperature dependence. These observations manifest the N-H..Br-In hydrogen bond networks developed between the cations and anions to stabilize the crystal structures. The 81 Br NQR and differential thermal analysis (DTA) measurements have revealed the occurrence of unique phase transitions in 1 and 3. When the bond angles were estimated from the electric field gradient (EFG) directions calculated by the molecular orbital (MO) methods, accurate values were obtained for [InBr 6 ] 3- of 1 and for [In 2 Br 11 ] 5- and [InBr 4 ] - of 3, except for several exceptions in those for the latter two ions. On the other hand, the calculations of 81 Br NQR frequencies have produced up to 1.4 times higher values than the observed ones.

CH3Br adsorption on MgO/Mo ultrathin films: A DFT study

Science.gov (United States)

Cipriano, Luis A.; Tosoni, Sergio; Pacchioni, Gianfranco

2018-06-01

The adsorption of methyl bromide on MgO ultrathin films supported on Mo(100) was studied by means of density functional theory calculations, in comparison to the MgO(100) and Mo(100) surfaces. The adsorption energy and geometry were shown to depend on the thickness of the supported oxide film. MgO films as thick as 2ML (or more) display adsorptive properties similar to MgO(100), i.e. the adsorption of CH3Br is mostly due to dispersion and the molecule lies in a tilted geometry almost parallel to the surface. The CH3Br HOMO-LUMO gap is almost unaltered with respect to the gas phase. On metallic Mo(100) surfaces the bonding is completely different with the CH3Br molecule strongly bound and the C-Br bond axis almost vertical with respect to the metal surface. The MgO monolayer supported on Mo exhibits somehow intermediate properties: the tilt angle is larger and the bonding is stronger than on MgO(100), due to the effect of the supporting metal. In this case, a small reduction of the HOMO-LUMO gap of the adsorbed molecule is reported. The results help to rationalize the observed behavior in photodissociation of CH3Br supported on different substrates.

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.

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.

Elimination mechanisms of Br2+ and Br+ in photodissociation of 1,1- and 1,2-dibromoethylenes using velocity imaging technique

International Nuclear Information System (INIS)

Hua Linqiang; Zhang Bing; Lee, Wei-Bin; Chao, Meng-Hsuan; Lin, King-Chuen

2011-01-01

Elimination pathways of the Br 2 + and Br + ionic fragments in photodissociation of 1,2- and 1,1-dibromoethylenes (C 2 H 2 Br 2 ) at 233 nm are investigated using time-of-flight mass spectrometer equipped with velocity ion imaging. The Br 2 + fragments are verified not to stem from ionization of neutral Br 2 , that is a dissociation channel of dibromoethylenes reported previously. Instead, they are produced from dissociative ionization of dibromoethylene isomers. That is, C 2 H 2 Br 2 is first ionized by absorbing two photons, followed by the dissociation scheme, C 2 H 2 Br 2 + + hv→Br 2 + + C 2 H 2 . 1,2-C 2 H 2 Br 2 gives rise to a bright Br 2 + image with anisotropy parameter of -0.5 ± 0.1; the fragment may recoil at an angle of ∼66 deg. with respect to the C = C bond axis. However, this channel is relatively slow in 1,1-C 2 H 2 Br 2 such that a weak Br 2 + image is acquired with anisotropy parameter equal to zero, indicative of an isotropic recoil fragment distribution. It is more complicated to understand the formation mechanisms of Br + . Three routes are proposed for dissociation of 1,2-C 2 H 2 Br 2 , including (a) ionization of Br that is eliminated from C 2 H 2 Br 2 by absorbing one photon, (b) dissociation from C 2 H 2 Br 2 + by absorbing two more photons, and (c) dissociation of Br 2 + . Each pathway requires four photons to release one Br + , in contrast to the Br 2 + formation that involves a three-photon process. As for 1,1-C 2 H 2 Br 2 , the first two pathways are the same, but the third one is too weak to be detected.

Single crystal growth and surface chemical stability of KPb2Br5

Science.gov (United States)

Atuchin, V. V.; Isaenko, L. I.; Kesler, V. G.; Tarasova, A. Yu.

2011-03-01

Single crystal of KPb2Br5 has been grown using the Bridgman technique. Initially the synthesis of stoichiometric KPb2Br5 compound was performed from high purity bromide salts. Electronic structure of KPb2Br5 has been determined with X-ray photoelectron spectroscopy for powdered sample fabricated by grinding in air. Drastic chemical interaction of KPb2Br5 with atmosphere has not been detected. Chemical bonding in potassium- and lead-containing bromides is considered using binding energy differences ΔK=(BE K 2p3/2-BE Br 3d) and ΔPb=(BE Pb 4f7/2-BE Br 3d), respectively, as representative parameters.

Strong room-temperature ultraviolet to red excitons from inorganic organic-layered perovskites, (MX4 (M=Pb, Sn, Hg; X=I-, Br-)

Science.gov (United States)

Ahmad, Shahab; Prakash, G. Vijaya

2014-01-01

Many varieties of layered inorganic-organic (IO) perovskite of type (MX4 (where R: organic moiety, M: divalent metal, and X: halogen) were successfully fabricated and characterized. X-ray diffraction data suggest that these inorganic and organic structures are alternatively stacked up along c-axis, where inorganic mono layers are of extended corner-shared MX6 octahedra and organic spacers are the bi-layers of organic entities. These layered perovskites show unusual room-temperature exciton absorption and photoluminescence due to the quantum and dielectric confinement-induced enhancement in the exciton binding energies. A wide spectral range of optical exciton tunability (350 to 600 nm) was observed experimentally from systematic compositional variation in (i) divalent metal ions (M=Pb, Sn, Hg), (ii) halides (X=I and Br-), and (iii) organic moieties (R). Specific photoluminescence features are due to the structure of the extended MX42- network and the eventual electronic band structure. The compositionally dependent photoluminescence of these IO hybrids could be useful in various photonic and optoelectronic devices.

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.

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)

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.

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.

Stable Chloro- and Bromoxenate Cage Anions; [X3(XeO3)3]3- and [X4(XeO3)4]4- (X = Cl or Br).

Science.gov (United States)

Goettel, James T; Haensch, Veit G; Schrobilgen, Gary J

2017-06-28

The number of isolable compounds which contain different noble-gas-element bonds is limited for xenon and even more so for krypton. Examples of Xe-Cl bonds are rare, and prior to this work, no Xe-Br bonded compound had been isolated in macroscopic quantities. The syntheses, isolation, and characterization of the first compounds to contain Xe-Br bonds and their chlorine analogues are described in the present work. The reactions of XeO 3 with [N(CH 3 ) 4 ]Br and [N(C 2 H 5 ) 4 ]Br have provided two bromoxenate salts, [N(C 2 H 5 ) 4 ] 3 [Br 3 (XeO 3 ) 3 ] and [N(CH 3 ) 4 ] 4 [Br 4 (XeO 3 ) 4 ], in which the cage anions have Xe-Br bond lengths that range from 3.0838(3) to 3.3181(8) Å. The isostructural chloroxenate anions (Xe-Cl bond lengths, 2.9316(2) to 3.101(4) Å) were synthesized by analogy with their bromine analogues. The bromo- and chloroxenate salts are stable in the atmosphere at room temperature and were characterized in the solid state by Raman spectroscopy and low-temperature single-crystal X-ray diffraction, and in the gas phase by quantum-chemical calculations. They are the only known examples of cage anions that contain a noble-gas element. The Xe-Br and Xe-Cl bonds are very weakly covalent and can be viewed as σ-hole interactions, similar to those encountered in halogen bonding. However, the halogen atoms in these cases are valence electron lone pair donors, and the σ* Xe-O orbitals are lone pair acceptors.

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.

248 nm photolysis of CH2Br2 by using cavity ring-down absorption spectroscopy: Br2 molecular elimination at room temperature.

Science.gov (United States)

Wei, Pei-Ying; Chang, Yuan-Ping; Lee, Wei-Bin; Hu, Zhengfa; Huang, Hong-Yi; Lin, King-Chuen; Chen, K T; Chang, A H H

2006-10-07

Following photodissociation of CH2Br2 at 248 nm, Br2 molecular elimination is detected by using a tunable laser beam, as crossed perpendicular to the photolyzing laser beam in a ring-down cell, probing the Br2 fragment in the B 3Piou+ -X 1Sigmag+ transition. The nascent vibrational population is obtained, yielding a population ratio of Br2(v = 1)Br2(v = 0) to be 0.7 +/- 0.2. The quantum yield for the Br2 elimination reaction is determined to be 0.2 +/- 0.1. Nevertheless, when CH2Br2 is prepared in a supersonic molecular beam under cold temperature, photofragmentation gives no Br2 detectable in a time-of-flight mass spectrometer. With the aid of ab initio potential energy calculations, a plausible pathway is proposed. Upon excitation to the 1B1 or 3B1 state, C-Br bond elongation may change the molecular symmetry of Cs and enhance the resultant 1 1,3A'-X 1A' (or 1 1,3B1-X 1A1 as C2v is used) coupling to facilitate the process of internal conversion, followed by asynchronous concerted photodissociation. Temperature dependence measurements lend support to the proposed pathway.

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.

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)

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.

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

Multiple Hydrogen-Bond Activation in Asymmetric Brønsted Acid Catalysis

KAUST Repository

Liao, Hsuan-Hung

2018-05-03

An efficient protocol for the asymmetric synthesis of chiral tetrahydroquinolines bearing multiple stereogenic centers by means of asymmetric Brønsted acid catalysis was developed. A chiral 1,1′‐spirobiindane‐7,7′‐diol (SPINOL)‐based N‐triflylphosphoramide (NTPA) proved to be an effective Brønsted acid catalyst for the in situ generation of aza‐ortho‐quinone methides (aza‐o‐QMs) and their subsequent cycloaddition reaction with unactivated alkenes to provide the products with excellent diastereo‐ and enantioselectivities. In addition, DFT calculations provided insight into the activation mode and nature of the interactions between the N‐triflylphosphoramide catalyst and the generated aza‐o‐QMs.

Multiple Hydrogen-Bond Activation in Asymmetric Brønsted Acid Catalysis

KAUST Repository

Liao, Hsuan-Hung; Hsiao, Chien-Chi; Atodiresei, Iuliana; Rueping, Magnus

2018-01-01

An efficient protocol for the asymmetric synthesis of chiral tetrahydroquinolines bearing multiple stereogenic centers by means of asymmetric Brønsted acid catalysis was developed. A chiral 1,1′‐spirobiindane‐7,7′‐diol (SPINOL)‐based N‐triflylphosphoramide (NTPA) proved to be an effective Brønsted acid catalyst for the in situ generation of aza‐ortho‐quinone methides (aza‐o‐QMs) and their subsequent cycloaddition reaction with unactivated alkenes to provide the products with excellent diastereo‐ and enantioselectivities. In addition, DFT calculations provided insight into the activation mode and nature of the interactions between the N‐triflylphosphoramide catalyst and the generated aza‐o‐QMs.

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.

High Defect Tolerance in Lead Halide Perovskite CsPbBr3.

Science.gov (United States)

Kang, Jun; Wang, Lin-Wang

2017-01-19

The formation energies and charge-transition levels of intrinsic point defects in lead halide perovskite CsPbBr 3 are studied from first-principles calculations. It is shown that the formation energy of dominant defect under Br-rich growth condition is much lower than that under moderate or Br-poor conditions. Thus avoiding the Br-rich condition can help to reduce the defect concentration. Interestingly, CsPbBr 3 is found to be highly defect-tolerant in terms of its electronic structure. Most of the intrinsic defects induce shallow transition levels. Only a few defects with high formation energies can create deep transition levels. Therefore, CsPbBr 3 can maintain its good electronic quality despite the presence of defects. Such defect tolerance feature can be attributed to the lacking of bonding-antibonding interaction between the conduction bands and valence bands.

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.

Thermodynamic assessment of EuBr2 unary and LiBr-EuBr2 and NaBr-EuBr2 binary systems

International Nuclear Information System (INIS)

Gong, Weiping; Gaune-Escard, Marcelle

2009-01-01

As a basis for the design and development of molten salt mixtures, thermodynamic calculations of the phase diagrams and thermodynamic properties were carried out on the EuBr 2 unary and LiBr-EuBr 2 and NaBr-EuBr 2 binary systems over a wide temperature and composition range, respectively. The Gibbs energy of EuBr 2 was evaluated using an independent polynomial to fit the experimental heat capacity, the thermodynamic parameters for each phase in the LiBr-EuBr 2 and NaBr-EuBr 2 systems were optimized by using available experimental information on phase diagrams. A regular substitutional solution model for the liquid phase and Neumann-Kopp rule for the stoichiometric compound LiEu 2 Br 5 were adopted to reproduce the experimental data with reasonable excess Gibbs energy. Comparisons between the calculated phase diagrams and thermodynamic quantities show that all reliable experimental information is satisfactorily accounted for by the present thermodynamic description. Some thermodynamic properties were predicted to check the suitability of the present calculation.

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

Ge14 Br8 (PEt3 )4 : A Subhalide Cluster of Germanium.

Science.gov (United States)

Kunz, Tanja; Schrenk, Claudio; Schnepf, Andreas

2018-04-03

Heating a metastable solution of Ge I Br to room temperature led to the first structurally characterized metalloid subhalide cluster Ge 14 Br 8 (PEt 3 ) 4 (1). Furthermore 1 can be seen as the first isolated binary halide cluster on the way from Ge I Br to elemental germanium, giving insight into the complex reaction mechanism of its disproportionation reaction. Quantum chemical calculations further indicate that a classical bonding situation is realized within 1 and that the last step of the formation of 1 might include the trapping of GeBr 2 units. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Pathways for the OH + Br2 → HOBr + Br and HOBr + Br → HBr + BrO Reactions.

Science.gov (United States)

Wang, Hongyan; Qiu, Yudong; Schaefer, Henry F

2016-02-11

The OH radical reaction with Br2 and the subsequent reaction HOBr + Br are of exceptional importance to atmospheric chemistry and environmental chemistry. The entrance complex, transition state, and exit complex for both reactions have been determined using the coupled-cluster method with single, double, and perturbative triple excitations CCSD(T) with correlation consistent basis sets up to size cc-pV5Z and cc-pV5Z-PP. Coupled cluster effects with full triples (CCSDT) and full quadruples (CCSDTQ) are explicitly investigated. Scalar relativistic effects, spin-orbit coupling, and zero-point vibrational energy corrections are evaluated. The results from the all-electron basis sets are compared with those from the effective core potential (ECP) pseudopotential (PP) basis sets. The results are consistent. The OH + Br2 reaction is predicted to be exothermic 4.1 ± 0.5 kcal/mol, compared to experiment, 3.9 ± 0.2 kcal/mol. The entrance complex HO···BrBr is bound by 2.2 ± 0.2 kcal/mol. The transition state lies similarly well below the reactants OH + Br2. The exit complex HOBr···Br is bound by 2.7 ± 0.6 kcal/mol relative to separated HOBr + Br. The endothermicity of the reaction HOBr + Br → HBr + BrO is 9.6 ± 0.7 kcal/mol, compared with experiment 8.7 ± 0.3 kcal/mol. For the more important reverse (exothermic) HBr + BrO reaction, the entrance complex BrO···HBr is bound by 1.8 ± 0.6 kcal/mol. The barrier for the HBr + BrO reaction is 6.8 ± 0.9 kcal/mol. The exit complex (Br···HOBr) for the HBr + BrO reaction is bound by 1.9 ± 0.2 kcal/mol with respect to the products HOBr + Br.

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.

Orthodontic bracket bonding to glazed full-contour zirconia

Directory of Open Access Journals (Sweden)

Ji-Young Kwak

2016-05-01

Full Text Available Objectives This study evaluated the effects of different surface conditioning methods on the bond strength of orthodontic brackets to glazed full-zirconia surfaces. Materials and Methods Glazed zirconia (except for the control, Zirkonzahn Prettau disc surfaces were pre-treated: PO (control, polishing; BR, bur roughening; PP, cleaning with a prophy cup and pumice; HF, hydrofluoric acid etching; AA, air abrasion with aluminum oxide; CJ, CoJet-Sand. The surfaces were examined using profilometry, scanning electron microscopy, and electron dispersive spectroscopy. A zirconia primer (Z-Prime Plus, Z or a silane primer (Monobond-S, S was then applied to the surfaces, yielding 7 groups (PO-Z, BR-Z, PP-S, HF-S, AA-S, AA-Z, and CJ-S. Metal bracket-bonded specimens were stored in water for 24 hr at 37℃, and thermocycled for 1,000 cycles. Their bond strengths were measured using the wire loop method (n = 10. Results Except for BR, the surface pre-treatments failed to expose the zirconia substructure. A significant difference in bond strengths was found between AA-Z (4.60 ± 1.08 MPa and all other groups (13.38 ± 2.57 - 15.78 ± 2.39 MPa, p < 0.05. For AA-Z, most of the adhesive remained on the bracket. Conclusions For bracket bonding to glazed zirconia, a simple application of silane to the cleaned surface is recommended. A zirconia primer should be used only when the zirconia substructure is definitely exposed.

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.

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).

Exploring the C-X…π Halogen Bonding Motif: An Infrared and Raman Study of the Complexes of CF3X (X = Cl, Br and I with the Aromatic Model Compounds Benzene and Toluene

Directory of Open Access Journals (Sweden)

Wouter A. Herrebout

2013-06-01

Full Text Available The formation of halogen bonded complexes formed between the trifluorohalomethanes CF3Cl, CF3Br and CF3I and the Lewis bases benzene and toluene at temperatures below 150K was investigated using FTIR and Raman spectroscopy. Experiments using liquid krypton as solvent show that for both CF3Br and CF3I substantial fractions of the monomers can be involved in 1:1 complexes. In addition, weak absorptions illustrating the formation of 2:1 complexes between CF3I and benzene are observed. Using spectra recorded at temperatures between 120 and 140 K, observed information on the relative stability was obtained for all complexes by determining the complexation enthalpies in solution. The resulting values for CF3Br.benzene, CF3I.benzene and (CF3I2.benzene are −6.5(3, −7.6(2 and −14.5(9 kJ mol−1. The values for CF3Br.toluene and CF3I.toluene are −6.2(5 and −7.4(5 kJ mol−1. The experimental complexation enthalpies are compared with theoretical data obtained by combining results from MP2/aug-cc-pVDZ(-PP and MP2/aug-cc-pVTZ(-PP ab initio calculations, from statistical thermodynamical calculations and from Monte Carlo Free Energy Perturbation simulations. The data are also compared with results derived for other C-X···π halogen bonded complexes involving unsaturated Lewis bases such as ethene and ethyne.

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.

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.

New insight on the local structure of Cu2+ ion in the solution of CuBr2 by EXAFS studies

International Nuclear Information System (INIS)

Yu Meijuan; Chu Wangsheng; Chen Xing; Wu Ziyu

2009-01-01

CuBr 2 solutions at different concentrations were studied by extended X-ray absorption fine structure (EXAFS) at the Cu K edge. In the saturated solution Cu 2+ ions have chemical bonds with 3.0 oxygen atoms and 0.9 Br ion at about 1.96 A and 2.42 A, respectively. It indicates that the CuBr 4 -2 configuration exists with a ratio of 25% under this condition. In the dilute solutions no evidence of Br ions contributions in the first shell around Cu 2+ ions occurs. The almost identical X-ray absorption near edge structure (XANES) and EXAFS characters address similar local environments around Cu 2+ in agreement with results of the EXAFS fit taking into account only the contributions of Cu-O bonds.

Novel Co(III)/Co(II) mixed valence compound [Co(bapen)Br2]2[CoBr4] (bapen = N,N‧-bis(3-aminopropyl)ethane-1,2-diamine): Synthesis, crystal structure and magnetic properties

Science.gov (United States)

Smolko, Lukáš; Černák, Juraj; Kuchár, Juraj; Miklovič, Jozef; Boča, Roman

2016-09-01

Green crystals of Co(III)/Co(II) mixed valence compound [Co(bapen)Br2]2[CoBr4] (bapen = N,N‧-bis(3-aminopropyl)ethane-1,2-diamine) were isolated from the aqueous system CoBr2 - bapen - HBr, crystallographically studied and characterized by elemental analysis and IR spectroscopy. Its ionic crystal structure is built up of [Co(bapen)Br2]+ cations and [CoBr4]2- anions. The Co(III) central atoms within the complex cations are hexacoordinated (donor set trans-N4Br2) with bromido ligands placed in the axial positions. The Co(II) atoms exhibit distorted tetrahedral coordination. Beside ionic forces weak Nsbnd H⋯Br intermolecular hydrogen bonding interactions contribute to the stability of the structure. Temperature variable magnetic measurements confirm the S = 3/2 behavior with the zero-field splitting of an intermediate strength: D/hc = 8.7 cm-1.

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.

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.

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.

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

X-ray and NQR studies of bromoindate(III) complexes. [C{sub 2}H{sub 5}NH{sub 3}]{sub 4}InBr{sub 7}, [C(NH{sub 2}){sub 3}]{sub 3}InBr{sub 6}, and [H{sub 3}NCH{sub 2}C(CH{sub 3}){sub 2}CH{sub 2}NH{sub 3}]InBr{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Iwakiri, Takeharu; Ishihara, Hideta [Saga Univ. (Japan). Faculty of Culture and Education; Terao, Hiromitsu [Tokushima Univ. (Japan). Faculty of Integrated Arts and Sciences; Lork, Enno; Gesing, Thorsten M. [Bremen Univ. (Germany). Inst. of Inorganic Chemistry and Crystallography

2017-03-01

The crystal structures of [C{sub 2}H{sub 5}NH{sub 3}]{sub 4}InBr{sub 7}(1), [C(NH{sub 2}){sub 3}]{sub 3}InBr{sub 6}(2), and [H{sub 3}NCH{sub 2}C(CH{sub 3}){sub 2}CH{sub 2}NH{sub 3}]InBr{sub 5}(3) were determined at 100(2) K: monoclinic, P2{sub 1}/n, a=1061.94(3), b=1186.40(4), c=2007.88(7) pm, β= 104.575(1) , Z=4 for 1; monoclinic, C2/c, a=3128.81(12), b=878.42(3), c=2816.50(10) pm, β=92.1320(10) , Z=16 for 2; orthorhombic, P2{sub 1}2{sub 1}2{sub 1}, a=1250.33(5), b=1391.46(6), c=2503.22(9) pm, Z=4 for 3. The structure of 1 contains an isolated octahedral [InBr{sub 6}]{sup 3-} ion and a Br{sup -} ion. The structure of 2 contains three different isolated octahedral [InBr{sub 6}]{sup 3-} ions. The structure of 3 has a corner-shared double-octahedral [In{sub 2}Br{sub 11}]{sup 5-} ion and an isolated tetrahedral [InBr{sub 4}]{sup -} ion. The {sup 81}Br nuclear quadrupole resonance (NQR) lines of the terminal Br atoms of the compounds are widely spread in frequency, and some of them show unusual positive temperature dependence. These observations manifest the N-H..Br-In hydrogen bond networks developed between the cations and anions to stabilize the crystal structures. The {sup 81}Br NQR and differential thermal analysis (DTA) measurements have revealed the occurrence of unique phase transitions in 1 and 3. When the bond angles were estimated from the electric field gradient (EFG) directions calculated by the molecular orbital (MO) methods, accurate values were obtained for [InBr{sub 6}]{sup 3-} of 1 and for [In{sub 2}Br{sub 11}]{sup 5-} and [InBr{sub 4}]{sup -} of 3, except for several exceptions in those for the latter two ions. On the other hand, the calculations of {sup 81}Br NQR frequencies have produced up to 1.4 times higher values than the observed ones.

Thermodynamic assessment of NdBr3 unary and LiBr-NdBr3 binary system

International Nuclear Information System (INIS)

Gong Weiping; Gaune-Escard, Marcelle

2006-01-01

Phase diagram and thermodynamic properties calculations were carried out on the NdBr 3 unary and the LiBr-NdBr 3 binary systems over the entire temperature and composition range, respectively. The Gibbs energy of NdBr 3 was evaluated using an independent polynomial to fit the experimental thermodynamic properties. The liquid phase in the LiBr-NdBr 3 system was described by the two sub-lattice ionic solution model (Li + ) P : (Br - , NdBr 6 -3 , NdBr 3 ) Q . Comparisons between the calculated phase diagram and thermodynamic quantities show that all reliable experimental information was satisfactorily accounted for by the present thermodynamic description

3+ and [Sb13Se16Br2] 5+ - Double and quadruple spiro cubanes from ionic liquids

KAUST Repository

Ahmed, Ejaz

2014-01-08

The reaction of antimony and selenium in the bromine-rich Lewis acidic ionic liquid [BMIm]Br·4.7AlBr3 (BMIm: 1-butyl-3- methylimidazolium) in the presence of a small amount of NbCl5 at 160 °C yielded dark-red crystals of [Sb7Se8Br 2][AlX4]3. For X = Cl0.15(1)Br 0.85(1), the compound is isostructural to [Sb7S 8Br2][AlCl4]3 [P212 121, a = 12.5132(5) Å, b = 17.7394(6) Å, c = 18.3013(6) Å]. For a higher chlorine content, X = Cl 0.58(1)Br0.42(1), a slightly disordered variant with a bisected unit cell is found [P21212, a = 12.3757(3) Å, b = 17.4116(5) Å, c = 9.0420(2) Å]. The [Sb 7Se8Br2]3+ heteropolycation (C 2 symmetry) is a spiro double-cubane with an antimony atom on the shared corner. From this distorted octahedrally coordinated central atom, tricoordinate selenium and antimony atoms alternate in the bonding sequence. The terminal antimony atoms each bind to a bromine atom. Quantum chemical calculations confirm polar covalent Sb-Se bonding within the cubes and indicate three-center, four-electron bonds for the six-coordinate spiro atoms. The calculated charge distribution reflects the electron-donor role of the antimony atoms. The use of a chlorine-rich ionic liquid resulted in the formation of triclinic [Sb13Se16Br2][AlX4] 5 with X = Cl0.80(1)Br0.20(1) [P$\\\\bar {1}$, a = 9.0842(5) Å, b = 19.607(1) Å, c = 21.511(1) Å, α = 64.116(6), β = 79.768(7), γ = 88.499(7)]. The cationic cluster [Sb13Se16Br2]5+ is a bromine-terminated spiro quadruple-cubane. This 31 atom concatenation of four cubes is assumed to be the largest known discrete main group polycation. A similar reaction in a chloride-free system yielded [Sb7Se 8Br2][Sb13Se16Br2] [AlBr4]8. In its monoclinic structure [P2/c, a = 27.214(5) Å, b = 9.383(2) Å, c = 22.917(4) Å, β = 101.68(1)], the two types of polycations alternate in layers along the a axis. In the series [Sb4+3nSe4+4nBr2](2+n)+, these cations are the members with n = 1 and 3. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGa

A theoretical investigation of Brønsted acids chemisorption on ZnO(0001)

Science.gov (United States)

Casarin, Maurizio; Maccato, Chiara; Tondello, Eugenio; Vittadini, Andrea

1995-12-01

Density functional theory coupled to the molecular cluster approach has been used to investigate the chemisorption of simple Brønsted acids (H 2O, H 2S and HCN) on the ZnO(0001) polar surface. Geometrical parameters and vibrational frequencies for species molecularly and dissociatively chemisorbed have been computed. The agreement with experimental measurements, when available, has been found to be very good. The nature of the bonding between the conjugate base of each examined Brønsted acid and the Lewis acid site on the investigated surface has been thoroughly discussed. In particular, it has been elucidated the role played by the interaction between completely occupied levels in determining the actual chemisorption geometry. Enthalpy variations associated to titration displacement reactions have been evaluated, confirming the leading role played by the bonding between the Brønsted conjugate base anions and the Lewis acid site available on the surface in determining the actual relative acidity scale. The strength of this interaction follows the order OH - ≈ CN ->SH -.

Two new 3-D cadmium bromoplumbates: the only example of heterometallic bromoplumbate based on crown [Cd(Pb4O4)Br2] clusters.

Science.gov (United States)

Xiao, Hong; Zhou, Jian; Liu, Xing

2018-04-03

Two new cadmium bromoplumbates [CdPb2Br2L2]n (1, L = ethylene glycol) and [CdPb6Br6L4]n (2) have been solvothermally synthesized and structurally characterized. 1 contains 1-D neutral heterometallic chains [CdPb2Br2L2]n, which are further connected via weak Pb-Br bonds, resulting in a 3-D network structure. The 3-D framework of 2 is constructed by the interconnection of a 2-D neutral layer [CdPb6Br6L4]nvia weak Pb-Br bonds. The [CdPb6Br6L4]n layer is based on the linkages of dimeric [Pb2Br4] units and heterometallic crown [Cd(Pb4O4)Br2] clusters containing a rare eight-membered [Pb4O4] ring. Although a few heterometallic bromoplumbate clusters have been reported, they usually exhibit molecular moieties. 2 represents the only example of 3-D heterometallic bromoplumbate based on the combination of heterometallic crown [Cd(Pb4O4)Br2] clusters and dimeric [Pb2Br4] units. Their optical properties are studied and density functional theory calculations for 1 and 2 have also been performed.

Behavior of Halogen Bonds of the Y-X⋅⋅⋅π Type (X, Y=F, Cl, Br, I) in the Benzene π System, Elucidated by Using a Quantum Theory of Atoms in Molecules Dual-Functional Analysis.

Science.gov (United States)

Sugibayashi, Yuji; Hayashi, Satoko; Nakanishi, Waro

2016-08-18

The nature of halogen bonds of the Y-X-✶-π(C6 H6 ) type (X, Y=F, Cl, Br, and I) have been elucidated by using the quantum theory of atoms in molecules (QTAIM) dual-functional analysis (QTAIM-DFA), which we proposed recently. Asterisks (✶) emphasize the presence of bond-critical points (BCPs) in the interactions in question. Total electron energy densities, Hb (rc ), are plotted versus Hb (rc )-Vb (rc )/2 [=(ħ(2) /8m)∇(2) ρb (rc )] for the interactions in QTAIM-DFA, in which Vb (rc ) are potential energy densities at the BCPs. Data for perturbed structures around fully optimized structures were used for the plots, in addition to those of the fully optimized ones. The plots were analyzed by using the polar (R, θ) coordinate for the data of fully optimized structures with (θp , κp ) for those that contained the perturbed structures; θp corresponds to the tangent line of the plot and κp is the curvature. Whereas (R, θ) corresponds to the static nature, (θp , κp ) represents the dynamic nature of the interactions. All interactions in Y-X-✶-π(C6 H6 ) are classified by pure closed-shell interactions and characterized to have vdW nature, except for Y-I-✶-π(C6 H6 ) (Y=F, Cl, Br) and F-Br-✶-π(C6 H6 ), which have typical hydrogen-bond nature without covalency. I-I-✶-π(C6 H6 ) has a borderline nature between the two. Y-F-✶-π(C6 H6 ) (Y=Br, I) were optimized as bent forms, in which Y-✶-π interactions were detected. The Y-✶-π interactions in the bent forms are predicted to be substantially weaker than those in the linear F-Y-✶-π(C6 H6 ) forms. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

2-{2,4,6-Tris(bromomethyl-3,5-bis[(1,3-dioxoisoindolin-2-ylmethyl]benzyl}isoindoline-1,3-dione toluene monosolvate

Directory of Open Access Journals (Sweden)

Niklas Koch

2014-04-01

Full Text Available In the title compound, C36H24Br3N3O6·C7H8, the toluene solvent molecule is associated with the receptor molecule via C—H...π bonding. The planes of the phthalimido groups are inclined at 77.0 (1, 63.0 (1 and 77.8 (1° with respect to the benzene ring. The molecular conformation is stabilized by C—H...O and C—H...Br hydrogen bonds. The crystal structure features non-classical hydrogen bonds of the C—H...N, C—H...O and C—H...Br type, leading to a three-dimensional cross-linking of molecules. The pattern of non-covalent intermolecular bonding is completed by O...Br halogen bonds [3.306 (3 Å], which link the receptor molecules into infinite strands extending along the a-axis direction.

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.

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.

Theoretical studies on photoelectron and IR spectral properties of Br2.-(H2O)n clusters.

Science.gov (United States)

Pathak, A K; Mukherjee, T; Maity, D K

2007-07-28

We report vertical detachment energy (VDE) and IR spectra of Br2.-.(H2O)n clusters (n=1-8) based on first principles electronic structure calculations. Cluster structures and IR spectra are calculated at Becke's half-and-half hybrid exchange-correlation functional (BHHLYP) with a triple split valence basis function, 6-311++G(d,p). VDE for the hydrated clusters is calculated based on second order Moller-Plesset perturbation (MP2) theory with the same set of basis function. On full geometry optimization, it is observed that conformers having interwater hydrogen bonding among solvent water molecules are more stable than the structures having double or single hydrogen bonded structures between the anionic solute, Br2.-, and solvent water molecules. Moreover, a conformer having cyclic interwater hydrogen bonded network is predicted to be more stable for each size hydrated cluster. It is also noticed that up to four solvent H2O units can reside around the solute in a cyclic interwater hydrogen bonded network. The excess electron in these hydrated clusters is localized over the solute atoms. Weighted average VDE is calculated for each size (n) cluster based on statistical population of the conformers at 150 K. A linear relationship is obtained for VDE versus (n+3)(-1/3) and bulk VDE of Br2.- aqueous solution is calculated as 10.01 eV at MP2 level of theory. BHHLYP density functional is seen to make a systematic overestimation in VDE values by approximately 0.5 eV compared to MP2 data in all the hydrated clusters. It is observed that hydration increases VDE of bromine dimer anion system by approximately 6.4 eV. Calculated IR spectra show that the formation of Br2.--water clusters induces large shifts from the normal O-H stretching bands of isolated water keeping bending modes rather insensitive. Hydrated clusters, Br2.-.(H2O)n, show characteristic sharp features of O-H stretching bands of water in the small size clusters.

Theoretical studies on photoelectron and IR spectral properties of Br2.-(H2O)n clusters

Science.gov (United States)

Pathak, A. K.; Mukherjee, T.; Maity, D. K.

2007-07-01

We report vertical detachment energy (VDE) and IR spectra of Br2•-•(H2O)n clusters (n=1-8) based on first principles electronic structure calculations. Cluster structures and IR spectra are calculated at Becke's half-and-half hybrid exchange-correlation functional (BHHLYP) with a triple split valence basis function, 6-311++G(d,p). VDE for the hydrated clusters is calculated based on second order Moller-Plesset perturbation (MP2) theory with the same set of basis function. On full geometry optimization, it is observed that conformers having interwater hydrogen bonding among solvent water molecules are more stable than the structures having double or single hydrogen bonded structures between the anionic solute, Br2•-, and solvent water molecules. Moreover, a conformer having cyclic interwater hydrogen bonded network is predicted to be more stable for each size hydrated cluster. It is also noticed that up to four solvent H2O units can reside around the solute in a cyclic interwater hydrogen bonded network. The excess electron in these hydrated clusters is localized over the solute atoms. Weighted average VDE is calculated for each size (n) cluster based on statistical population of the conformers at 150K. A linear relationship is obtained for VDE versus (n+3)-1/3 and bulk VDE of Br2•- aqueous solution is calculated as 10.01eV at MP2 level of theory. BHHLYP density functional is seen to make a systematic overestimation in VDE values by ˜0.5eV compared to MP2 data in all the hydrated clusters. It is observed that hydration increases VDE of bromine dimer anion system by ˜6.4eV. Calculated IR spectra show that the formation of Br2•--water clusters induces large shifts from the normal O-H stretching bands of isolated water keeping bending modes rather insensitive. Hydrated clusters, Br2•-•(H2O)n, show characteristic sharp features of O-H stretching bands of water in the small size clusters.

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.

Electronic parameters and top surface chemical stability of RbPb{sub 2}Br{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.ru [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Isaenko, L.I. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Kesler, V.G. [Laboratory of Physical Principles for Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Pokrovsky, L.D. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Tarasova, A.Yu. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

2012-01-16

Highlights: Black-Right-Pointing-Pointer Bridgman growth of RbPb{sub 2}Br{sub 5} crystal. Black-Right-Pointing-Pointer Electronic structure measurements with XPS. Black-Right-Pointing-Pointer Optical crystalline surface fabrication. - Abstract: The RbPb{sub 2}Br{sub 5} crystal has been grown by Bridgman method. The electronic structure of RbPb{sub 2}Br{sub 5} has been measured with XPS for a powder sample. High chemical stability of RbPb{sub 2}Br{sub 5} surface is verified by weak intensity of O 1s core level recorded by XPS and structural RHEED measurements. Chemical bonding effects have been observed by the comparative analysis of element core levels and crystal structure of RbPb{sub 2}Br{sub 5} and several rubidium- and lead-containing bromides using binding energy difference parameters {Delta}{sub Rb} = (BE Rb 3d - BE Br 3d) and {Delta}{sub Pb} = (BE Pb 4f{sub 7/2} - BE Br 3d).

New insight on the local structure of Cu{sup 2+} ion in the solution of CuBr{sub 2} by EXAFS studies

Energy Technology Data Exchange (ETDEWEB)

Yu Meijuan; Chu Wangsheng; Chen Xing; Wu Ziyu, E-mail: wuzy@ustc.edu.c [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049 (China)

2009-11-15

CuBr{sub 2} solutions at different concentrations were studied by extended X-ray absorption fine structure (EXAFS) at the Cu K edge. In the saturated solution Cu{sup 2+} ions have chemical bonds with 3.0 oxygen atoms and 0.9 Br ion at about 1.96 A and 2.42 A, respectively. It indicates that the CuBr{sub 4}{sup -2} configuration exists with a ratio of 25% under this condition. In the dilute solutions no evidence of Br ions contributions in the first shell around Cu{sup 2+} ions occurs. The almost identical X-ray absorption near edge structure (XANES) and EXAFS characters address similar local environments around Cu{sup 2+} in agreement with results of the EXAFS fit taking into account only the contributions of Cu-O bonds.

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.

Redetermination of the Crystal Structure of Al2Br6

DEFF Research Database (Denmark)

Berg, Rolf W.; Poulsen, Finn W.; Nielsen, Kurt

1997-01-01

. In accordance with previous results, the structure belongs to the monoclinic space group P2(1)/a, no. 14, C-2h(5), with a = 10.301(4), b = 7.095(2), c = 7.525(3) Angstrom, and beta = 96.44(3)degrees, and with two Al2Br6 molecules per unit cell. The single crystal was refined to R = 0.0746. Rather similar......The structure of aluminium bromide has been reinvestigated by X-ray diffraction in three different ways: (a) on a single crystal grown in a glass capillary, (b) on powder in a Debye-Scherrer glass capillary and (c) on an area of powder placed in a protective container for Bragg-Brentano geometry...... structural results were obtained from full-profile Rietveld refinements of powder data [goodness of fit = 1.38 and 2.54 for (b) and (c), respectively]. The Al2Br6 molecule consists of two edge-sharing, almost regular AlBr4 tetrahedra. The Al-Br bond distances are in the range 2.21-2.42 Angstrom...

Bromine-rich Zinc Bromides: Zn6Br12(18-crown-6)2×(Br2)5, Zn4Br8(18-crown-6)2×(Br2)3, and Zn6Br12(18-crown-6)2×(Br2)2.

Science.gov (United States)

Hausmann, David; Feldmann, Claus

2016-06-20

The bromine-rich zinc bromides Zn6Br12(18-crown-6)2×(Br2)5 (1), Zn4Br8(18-crown-6)2×(Br2)3 (2), and Zn6Br12(18-crown-6)2×(Br2)2 (3) are prepared by reaction of ZnBr2, 18-crown-6, and elemental bromine in the ionic liquid [MeBu3N][N(Tf)2] (N(Tf)2 = bis(trifluoromethylsulfonyl)amide). Zn6Br12(18-crown-6)2×(Br2)5 (1) is formed instantaneously by the reaction. Even at room temperature, compound 1 releases bromine, which was confirmed by thermogravimetry (TG) and mass spectrometry (MS). The release of Br2 can also be directly followed by the color and density of the title compounds. With controlled conditions (2 weeks, 25 °C, absence of excess Br2) Zn6Br12(18-crown-6)2×(Br2)5 (1) slowly releases bromine with conconcurrent generation of Zn4Br8(18-crown-6)2×(Br2)3 (2) (in ionic liquid) and Zn6Br12(18-crown-6)2×(Br2)2 (3) (in inert oil). All bromine-rich zinc bromides contain voluminous uncharged (e.g., Zn3Br6(18-crown-6), Zn2Br4(18-crown-6)) or ionic (e.g., [Zn2Br3(18-crown-6)](+), [(Zn2Br6)×(Br2)2](2-)) building units with dibromine molecules between the Zn oligomers and partially interconnecting the Zn-containing building units. Due to the structural similarity, the bromine release is possible via crystal-to-crystal transformation with retention of the crystal shape.

Hg0 and HgCl2 Reference Gas Standards: ?NIST Traceability ...

Science.gov (United States)

EPA and NIST have collaborated to establish the necessary procedures for establishing the required NIST traceability of commercially-provided Hg0 and HgCl2 reference generators. This presentation will discuss the approach of a joint EPA/NIST study to accurately quantify the true concentrations of Hg0 and HgCl2 reference gases produced from high quality, NIST-traceable, commercial Hg0 and HgCl2 generators. This presentation will also discuss the availability of HCl and Hg0 compressed reference gas standards as a result of EPA's recently approved Alternative Methods 114 and 118. Gaseous elemental mercury (Hg0) and oxidized mercury (HgCl2) reference standards are integral to the use of mercury continuous emissions monitoring systems (Hg CEMS) for regulatory compliance emissions monitoring. However, a quantitative disparity of approximately 7-10% has been observed between commercial Hg0 and HgCl2 reference gases which currently limits the use of (HgCl2) reference gas standards. Resolving this disparity would enable the expanded use of (HgCl2) reference gas standards for regulatory compliance purposes.

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

BR2 reactor: medical and industrial applications

International Nuclear Information System (INIS)

Ponsard, B.

2005-01-01

The radioisotopes are produced for various applications in the nuclear medicine (diagnostic, therapy, palliation of metastatic bone pain), industry (radiography of welds, ...), agriculture (radiotracers, ...) and basic research. Due to the availability of high neutron fluxes (thermal neutron flux up to 10 15 n/cm 2 .s), the BR2 reactor is considered as a major facility through its contribution for a continuous supply of products such 99 Mo ( 99 mTc), 131 I, 133 Xe, 192 Ir, 186 Re, 153 Sm, 90 Y, 32 P, 188 W ( 188 Re), 203 Hg, 82 Br, 41 Ar, 125 I, 177 Lu, 89 Sr, 60 Co, 169 Yb, 147 Nd, and others. Neutron Transmutation Doped (NTD) silicon is produced for the semiconductor industry in the SIDONIE (Silicon Doping by Neutron Irradiation Experiment) facility, which is designed to continuously rotate and traverse the silicon through the neutron flux. These combined movements produce exceptional dopant homogeneity in batches of silicon measuring 4 and 5-inches in diameter by up to 750 mm in length. The main objectives of work performed were to provide a reliable and qualitative supply of radioisotopes and NTD-silicon to the customers in accordance with a quality system that has been certified to the requirements of the EN ISO 9001: 2000. This new Quality System Certificate has been obtained in November 2003 for the Production of radioisotopes for medical and industrial applications and the Production of Neutron Transmutation Doped (NTD) Silicon in the BR2 reactor

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

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

Spontaneous stacking of purple membranes during immobilization with physical cross-linked poly(vinyl alcohol) hydrogel with retaining native-like functionality of bacteriorhodopsin

Science.gov (United States)

Yokoyama, Yasunori; Tanaka, Hikaru; Yano, Shunsuke; Takahashi, Hiroshi; Kikukawa, Takashi; Sonoyama, Masashi; Takenaka, Koshi

2017-05-01

We previously discovered the correlation between light-induced chromophore color change of a photo-receptor membrane protein bacteriorhodopsin (bR) and its two-dimensional crystalline state in the membrane. To apply this phenomenon to a novel optical memory device, it is necessary that bR molecules are immobilized as maintaining their structure and functional properties. In this work, a poly(vinyl alcohol) (PVA) hydrogel with physical cross-linkages (hydrogen bonds between PVA chains) that resulted from repeated freezing-and-thawing (FT) cycles was used as an immobilization medium. To investigate the effects of physically cross-linked PVA gelation on the structure and function of bR in purple membranes (PMs), spectroscopic techniques were employed against PM/PVA immobilized samples prepared with different FT cycle numbers. Visible circular dichroism spectroscopy strongly suggested PM stacking during gelation. X-ray diffraction data also indicated the PM stacking as well as its native-like crystalline lattice even after gelation. Time-resolved absorption spectroscopy showed that bR photocycle behaviors in PM/PVA immobilized samples were almost identical to that in suspension. These results suggested that a physically cross-linked PVA hydrogel is appropriate for immobilizing membrane proteins in terms of maintaining their structure and functionality.

Fluorescence Blinking and Photoactivation of All-Inorganic Perovskite Nanocrystals CsPbBr3 and CsPbBr2I.

Science.gov (United States)

Seth, Sudipta; Mondal, Navendu; Patra, Satyajit; Samanta, Anunay

2016-01-21

Study of the emission behavior of all-inorganic perovskite nanocrystals CsPbBr3 and CsPbBr2I as a function of the excitation power employing fluorescence correlation spectroscopy and conventional techniques reveals fluorescence blinking in the microsecond time scale and photoinduced emission enhancement. The observation provides insight into the radiative and nonradiative deactivation pathways of these promising substances. Because both blinking and photoactivation processes are intimately linked to the charge separation efficiency and dynamics of the nanocrystals, these key findings are likely to be helpful in realizing the true potential of these substances in photovoltaic and optoelectronic applications.

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.

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

Contributions of BrCl, Br2, BrOCl, Br2O, and HOBr to regiospecific bromination rates of anisole and bromoanisoles in aqueous solution.

Science.gov (United States)

Sivey, John D; Bickley, Mark A; Victor, Daniel A

2015-04-21

When bromide-containing waters are chlorinated, conventional wisdom typically assumes HOBr is the only active brominating agent. Several additional and often-overlooked brominating agents (including BrCl, Br2, BrOCl, Br2O) can form in chlorinated waters, albeit at generally lower concentrations than HOBr. The extent to which these additional brominating agents influence bromination rates of disinfection byproduct precursors is, however, poorly understood. Herein, the influence of BrCl, Br2, BrOCl, Br2O, and HOBr toward rates of sequential bromination of anisole was quantified. Conditions affecting bromine speciation (e.g., pH, concentrations of chloride, bromide, and chlorine) were varied, and regiospecific second-order rate constants were calculated for reactions of each brominating agent with anisole, 2-bromoanisole, and 4-bromoanisole. The regioselectivity of anisole bromination changed with pH, consistent with the participation of more than one brominating agent. Under conditions representative of chlorinated drinking water, contributions to bromination rates decreased as BrCl > BrOCl > HOBr > Br2O (Br2 negligible). The second-order rate constant determined for net bromination of anisole by HOBr is up to 3000-times less than reported in previous studies (which assumed HOBr was the only active brominating agent). Accordingly, models that assume HOBr is the only kinetically relevant brominating agent in solutions of free bromine may be insufficient for reactions involving modestly nucleophilic organic compounds.

Photodissociation of dibromoethanes at 248 nm: an ignored channel of Br2 elimination.

Science.gov (United States)

Lee, Hsin-Lung; Lee, Ping-Chen; Tsai, Po-Yu; Lin, King-Chuen; Kuo, H H; Chen, P H; Chang, A H H

2009-05-14

Br(2) molecular elimination is probed in the photodissociation of 1,1- and 1,2-C(2)H(4)Br(2) isomeric forms at 248 nm by using cavity ring-down absorption spectroscopy. Their photodissociation processes differ markedly from each other. The quantum yield of the Br(2) fragment in 1,2-dibromoethane is 0.36+/-0.18, in contrast to a value of 0.05+/-0.03 in 1,1-dibromoethane. The vibrational population ratios of Br(2)(v=1)/Br(2)(v=0) are 0.8+/-0.1 and 0.5+/-0.2 for 1,2- and 1,1-dibromoethanes, respectively. The Br(2) yield densities are found to increase by a factor of 35% and 190% for 1,2- and 1,1-dibromoethanes within the same temperature increment. In the ab initio potential energy calculations, the transition state (TS) along the adiabatic ground state surface may correlate to the Br(2) products. The TS energy for 1,2-dibromoethane is well below the excitation energy at 483 kJ/mol, whereas that for 1,1-dibromoethane is slightly above. Such a small TS energy barrier impedes the photodissociation of the ground state 1,1-dibromoethane such that the production yield of Br(2) may become relatively low, but rise rapidly with the temperature. The TS structure shows a larger bond distance of Br-Br in 1,2-dibromoethane than that in 1,1-dibromoethane. That explains why the former isomer may result in hotter vibrational population of the Br(2) fragments.

Zuotai and HgS differ from HgCl2 and methyl mercury in Hg accumulation and toxicity in weanling and aged rats.

Science.gov (United States)

Zhang, Bin-Bin; Li, Wen-Kai; Hou, Wei-Yu; Luo, Ya; Shi, Jing-Zhen; Li, Cen; Wei, Li-Xin; Liu, Jie

2017-09-15

Mercury sulfides are used in Ayurvedic medicines, Tibetan medicines, and Chinese medicines for thousands of years and are still used today. Cinnabar (α-HgS) and metacinnabar (β-HgS) are different from mercury chloride (HgCl 2 ) and methylmercury (MeHg) in their disposition and toxicity. Whether such scenario applies to weanling and aged animals is not known. To address this question, weanling (21d) and aged (450d) rats were orally given Zuotai (54% β-HgS, 30mg/kg), HgS (α-HgS, 30mg/kg), HgCl 2 (34.6mg/kg), or MeHg (MeHgCl, 3.2mg/kg) for 7days. Accumulation of Hg in kidney and liver, and the toxicity-sensitive gene expressions were examined. Animal body weight gain was decreased by HgCl 2 and to a lesser extent by MeHg, but unaltered after Zuotai and HgS. HgCl 2 and MeHg produced dramatic tissue Hg accumulation, increased kidney (kim-1 and Ngal) and liver (Ho-1) injury-sensitive gene expressions, but such changes are absent or mild after Zuotai and HgS. Aged rats were more susceptible than weanling rats to Hg toxicity. To examine roles of transporters in Hg accumulation, transporter gene expressions were examined. The expression of renal uptake transporters Oat1, Oct2, and Oatp4c1 and hepatic Oatp2 was decreased, while the expression of renal efflux transporter Mrp2, Mrp4 and Mdr1b was increased following HgCl 2 and MeHg, but unaffected by Zuotai and HgS. Thus, Zuotai and HgS differ from HgCl 2 and MeHg in producing tissue Hg accumulation and toxicity, and aged rats are more susceptible than weanling rats. Transporter expression could be adaptive means to reduce tissue Hg burden. Copyright © 2017 Elsevier Inc. All rights reserved.

Preparation, infrared, raman and nmr spectra of N,N'-diethylthiourea complexes with zinc(II), cadmium(II) and mercury(II) halides

Energy Technology Data Exchange (ETDEWEB)

Marcotrigiano, G [Bari Univ. (Italy). Cattedra di Chimica, Facolta di Medicina-Veterinaria

1976-05-01

Several complexes of N,N'-diethylthiourea (Dietu) with zinc(II), cadmium(II) and mercury(II) halides were prepared and characterized by i.r. (4000-60 cm/sup -1/), raman (400-60 cm/sup -1/), in the solid state and n.m.r. and conductometric methods in solution. The complexes Zn(Dietu)/sub 2/X/sub 2/, Cd(Dietu)/sub 2/X/sub 2/ (X=Cl, Br, I) and Hg(Dietu)/sub 2/X/sub 2/ (X=Br, I) are tetrahedral species in which intramolecular -NH...X interactions have been observed. The 1:1 mercury(II) complexes, Hg(Dietu)X/sub 2/ (X=Cl, Br), appear to have a dimeric tetrahedral halide-bridged structure in the solid state. In all these complexes N,N'-diethylthiourea is sulphur-bonded to the metal.

Temperature dependent absorption spectra of Br(-), Br2(•-), and Br3(-) in aqueous solutions.

Science.gov (United States)

Lin, Mingzhang; Archirel, Pierre; Van-Oanh, Nguyen Thi; Muroya, Yusa; Fu, Haiying; Yan, Yu; Nagaishi, Ryuji; Kumagai, Yuta; Katsumura, Yosuke; Mostafavi, Mehran

2011-05-05

The absorption spectra of Br(2)(•-) and Br(3)(-) in aqueous solutions are investigated by pulse radiolysis techniques from room temperature to 380 and 350 °C, respectively. Br(2)(•-) can be observed even in supercritical conditions, showing that this species could be used as a probe in pulse radiolysis at high temperature and even under supercritical conditions. The weak temperature effect on the absorption spectra of Br(2)(•-) and Br(3)(-) is because, in these two systems, the transition occurs between two valence states; for example, for Br(2)(-) we have (2)Σ(u) → (2)Σ(g) transition. These valence transitions involve no diffuse final state. However, the absorption band of Br(-) undergoes an important red shift to longer wavelengths. We performed classical dynamics of hydrated Br(-) system at 20 and 300 °C under pressure of 25 MPa. The radial distribution functions (rdf's) show that the strong temperature increase (from 20 to 300 °C) does not change the radius of the solvent first shell. On the other hand, it shifts dramatically (by 1 Å) the second maximum of the Br-O rdf and introduces much disorder. This shows that the first water shell is strongly bound to the anion whatever the temperature. The first two water shells form a cavity of a roughly spherical shape around the anion. By TDDFT method, we calculated the absorption spectra of hydrated Br(-) at two temperatures and we compared the results with the experimental data.

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.

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

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....

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.)

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.

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.

Void distributions in liquid BiBr{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Maruyama, K [Faculty of Science, Niigata University, Niigata 950-2181 (Japan); Endo, H [Faculty of Science, Kyoto University, Kyoto 606-8224 (Japan); Hoshino, H [Faculty of Education, Hirosaki University, Hirosaki 036-8560 (Japan); Kawakita, Y [Faculty of Sciences, Kyushu University, Fukuoka 810-8560 (Japan); Kohara, S; Itou, M [Japan Synchrotron Radiation Research Institute(JASRI), Sayo-cho 679-5198 (Japan)

2008-02-15

The X-ray diffraction experiments and the reverse Monte Carlo analysis for liquid BiBr{sub 3} have been performed to clarify the distribution of Bi and Br ions around voids, comparing with previous results derived in the neutron diffraction experiments. The hexagonal cages involving voids are formed by the corner-sharing of the trigonal pyramidal BiBr{sub 3} blocks. The neighboring cages are linked together in highly correlated fashion. The observed pre-peak in S(Q) at 1.3A{sup -1} is related to the pre-peak of the void-based S'{sub CC} (Q) due to an intermediate chemical order in the structure. The pre-peak intensity increases with increasing temperature. This characteristic change for the pre-peak intensity is discussed by considering the modifications of the topology and stacking in the hexagonal cages.

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.

Interaction mechanisms of ionic liquids [Cnmim]Br (n=4, 6, 8, 10) with bovine serum albumin

International Nuclear Information System (INIS)

Yan Hua; Wu Junyong; Dai Guoliang; Zhong Aiguo; Chen Hao; Yang Jianguo; Han Deman

2012-01-01

It is important to study the interaction of ionic liquids (ILs) with protein for the applications of ILs in biochemical process, and help the researchers to choose and design the better ILs to serve as a solvent. In this work, the interaction between 1-alkyl-3-methylimidazolium bromide [C n mim]Br (n=4, 6, 8, 10) and bovine serum albumin (BSA) was systematically investigated for the first time by multi-spectroscopic approach (fluorescence, UV–vis and FT-IR spectroscopy) and density functional theory (DFT). [C n mim]Br (n=4, 6, 8, 10) can bind to BSA by H-bond interaction between their cationic headgroups and Asp/Glu amino acid residue at the surface of BSA, and hydrophobic interaction between their hydrocarbon chains and the hydrophobic amino acid residues in the interior of BSA. On the basis of thermodynamic parameters and the similar structure of [C n mim]Br (n=4, 6, 8, 10), it can be inferred that the hydrophobic interaction plays a major role in the interaction of [C 10 mim]Br with BSA, while the hydrogen bond and van der Waals force play a major role in the interaction of [C n mim]Br (n=4, 6, 8) with BSA. Synchronous fluorescence and FT-IR spectra indicate that [C 10 mim]Br could markedly change the secondary structure of BSA, while [C n mim]Br (n=4, 6, 8) could slightly change the secondary structure of BSA. The results allowed us to understand (i) the effect of the alkyl chain length of the cation on the mechanism of ILs–protein interaction and (ii) the effect of the alkyl chain length of the cation on the protein secondary structure. - Highlights: ► Interaction of [C n mim]Br with BSA was investigated by spectroscopy and DFT. ► Interaction mechanisms and BSA secondary structure were discussed. ► Effects of the alkyl chain length of cation were presented.

Syntheses of halogenated polyhedral phosphaboranes: crystal structure of conjuncto-3,3{sup '}-(closo-1,2-P{sub 2}B{sub 4}Br{sub 3}){sub 2}

Energy Technology Data Exchange (ETDEWEB)

Keller, Willi [Institut fuer Chemie, Universitaet Hohenheim, Garbenstrasse 30, 70599, Stuttgart (Germany)

2017-04-18

Co-pyrolysis of B{sub 2}Br{sub 4} with PBr{sub 3} at 480 C gave, in addition to the main product closo-1,2-P{sub 2}B{sub 4}Br{sub 4}, conjuncto-3,3{sup '}-(1,2-P{sub 2}B{sub 4}Br{sub 3}){sub 2} (1) and the twelve-vertex closo-1,7-P{sub 2}B{sub 10}Br{sub 10} (2), both in low yields. X-ray structure determination for 1 [triclinic, space-group P1 with a = 7.220(2) Aa, b = 7.232(2) Aa, c = 8.5839(15) Aa, α = 97.213(15) , β = 96.81(2) , γ = 94.07(2) and Z = 1] confirmed that 1 adopts a structure consisting of two symmetrically boron-boron linked distorted octahedra with the bridging boron atoms in the 3,3{sup '}-positions and the phosphorus atoms in the 1,2-positions. The intercluster 2e/2c B-B bond length is 1.61(3) Aa. The shortest boron-boron bond within the cluster framework is 1.68(2) Aa located between the boron atoms antipodal to the phosphorus atoms. The icosahedral phosphaborane 2 was characterized by {sup 11}B-{sup 11}B COSY NMR spectroscopy showing cross peaks indicative for the isomer with the phosphorus atoms in 1,7-positions. Both the X-ray data of 1 and the NMR spectroscopic data of 1 and 2 give further evidence for the influence of an antipodal effect of heteroatoms to cross-cage boron atoms and, vice versa, of an additional shielding of the phosphorus atoms caused by B-Hal substitution at the boron positions trans to phosphorus. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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.

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.

Mercury coordination polymers with flexible ethane-1,2-diyl-bis-(pyridyl-3-carboxylate): Synthesis, structures, thermal and luminescent properties

Energy Technology Data Exchange (ETDEWEB)

Vallejos, Javier [Departamento de Química, Universidad Católica del Norte, Av. Angamos 0610, Antofagasta (Chile); Brito, Iván, E-mail: ivanbritob@yahoo.com [Departamento de Quimica, Universidad de Antofagasta, Av. Angamos 601, Antofagasta (Chile); Cárdenas, Alejandro [Departamento de Física, Universidad de Antofagasta, Av. Angamos 601, Antofagasta (Chile); Llanos, Jaime [Departamento de Química, Universidad Católica del Norte, Av. Angamos 0610, Antofagasta (Chile); Bolte, Michael [Institut für Anorganische Chemie der Goethe—Universität Frankfurt, Max-von-Laue-Strasse 7, D-60438 Frankfurt am Main (Germany); López-Rodríguez, Matías [Instituto de Bio-Orgánica “Antonio González”, Universidad de La Laguna, Astrofísico Francisco Sánchez N° 2, La Laguna, Tenerife (Spain)

2015-03-15

The reaction of the flexible ligand, ethane-1,2-diyl-bis-(pyridyl-3-carboxylate), (L) with HgI{sub 2} and HgBr{sub 2} salts under the same experimental conditions leads to the formation of two coordination polymers with different motifs: ([Hg(L)(Br{sub 2})]){sub n}(1) and ([Hg(L)(I{sub 2})]){sub n}(2). In both compounds, the ligand, (L) acts in a μ2-N:N′-bidentate fashion to link HgBr{sub 2} and HgI{sub 2} units to form a linear and helical chain motif, along [1 0 0] for (1) and [0 0 1] for (2). The ethylene moiety of (L) has gauche and trans conformation in compounds (1) and (2), respectively. The flexible conformation of L produces differences in the optical and crystal properties of the two compounds. - Graphical abstract: This work demonstrates how the HgX{sub 2} units are coordinates by bi-dentate ligand forming polymeric coordination complexes by self-assembly of both chemical units.- Highlights: • News 1-D d{sup 10} transition metal coordination polymers. • The photoluminescent properties have been measured. • The thermal properties have been measured.

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...

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.

Studies on the phase diagram of LiBr-SrBr2 system

International Nuclear Information System (INIS)

Mahendran, K.H.; Sujatha, K.; Sridharan, R.; Gnanasekaran, T.

2003-01-01

Binary LiBr-SrBr 2 system was investigated using differential scanning calorimetry (DSC) and the equilibrium phases at different compositions were identified using X-ray diffraction (XRD). This system has a compound LiSr 2 Br 5 , and exhibits a eutectic reaction between this compound and LiBr at 434 deg. C and the eutectic has a composition of 35 mol% SrBr 2 . The compound LiSr 2 Br 5 undergoes peritectic decomposition at 484 deg. C. From the DSC and XRD results, phase diagram of the LiBr-SrBr 2 system is constructed

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.

High Energy Performance Tests of Large Volume LaBr{sub 3}:Ce Detector

Energy Technology Data Exchange (ETDEWEB)

Naqvi, A.A.; Gondal, M.A.; Khiari, F.Z.; Dastageer, M.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Maslehuddin, M.M. [Center for Engineering Research, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Amoudi, O.S.B. [Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

2015-07-01

High energy prompt gamma ray tests of a large volume cylindrical 100 mm x 100 mm (height x diameter) LaBr{sub 3}:Ce detector were carried out using a portable neutron generator-based Prompt Gamma Neutron Activation Analysis (PGNAA) setup. In this study prompt gamma-rays yield were measured from water samples contaminated with toxic elements such nickel, chromium and mercury compounds with gamma ray energies up to 10 MeV. The experimental yield of prompt gamma-rays from toxic elements were compared with the results of Monte Carlo calculations. In spite of its higher intrinsic background due to its larger volume, an excellent agreement between the experimental and calculated yields of high energy gamma-rays from Ni, Cr and Hg samples has been achieved for the large volume LaBr{sub 3}:Ce detector. (authors)

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...

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

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 )

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

2013-04-28

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 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 risks inherent in extrapolating photochemical

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 ...

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

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.

Surfactant-promoted reactions of Cl2 and Br2 with Br- in glycerol.

Science.gov (United States)

Faust, Jennifer A; Dempsey, Logan P; Nathanson, Gilbert M

2013-10-17

Gas-liquid scattering experiments are used to explore reactions of gaseous Cl2 and Br2 with a 0.03 M solution of the surfactant tetrahexylammonium bromide (THABr) dissolved in glycerol. At thermal collision energies, 79 ± 2% of incident Cl2 molecules react with Br(-) to form Cl2Br(-) in the interfacial region. This reaction probability is three times greater than the reactivity of Cl2 with 3 M NaBr-glycerol, even though the interfacial Br(-) concentrations are similar in each solution. We attribute the high 79% uptake to the presence of surface THA(+) ions that stabilize the Cl2Br(-) intermediate as it is formed in the charged, hydrophobic pocket created by the hexyl chains. Cl2Br(-) generates the single exchange product BrCl in a 1% yield close to the surface, while the remaining 99% desorbs as the double exchange product Br2 over >0.1 s after diffusing deeply into the bulk. When NaCl is added to the surfactant solution in a 20:1 Cl(-)/Br(-) ratio, the Cl2 reaction probability drops from 79% to 46 ± 1%, indicating that Cl(-) in the interfacial region only partially blocks reaction with Br(-). In parallel, we observe that gaseous Br2 molecules dissolve in 0.03 M THABr for 10(4) times longer than in 3 M NaBr. We attribute this change to formation of stabilizing interfacial and bulk-phase THA(+)Br3(-) ion pairs, in analogy with the capture of Cl2 and formation of THA(+)Cl2Br(-) pairs. The THA(+) ion appears to be a powerful interfacial catalyst for promoting reaction of Cl2 and Br2 with Br(-) and for ferrying the resultant ions into solution.

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.

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.

Isomorphous Crystals from Diynes and Bromodiynes Involved in Hydrogen and Halogen Bonds

Directory of Open Access Journals (Sweden)

Pierre Baillargeon

2016-04-01

Full Text Available Isomorphous crystals of two diacetylene derivatives with carbamate functionality (BocNH-CH2-diyne-X, where X = H or Br have been obtained. The main feature of these structures is the original 2D arrangement (as supramolecular sheets or walls in which the H bond and halogen bond have a prominent effect on the whole architecture. The two diacetylene compounds harbor neighboring carbamate (Boc protected amine and conjugated alkyne functionalities. They differ only by the nature of the atom located at the penultimate position of the diyne moiety, either a hydrogen atom or a bromine atom. Both of them adopt very similar 2D wall organizations with antiparallel carbamates (as in antiparallel beta pleated sheets. Additional weak interactions inside the same walls between molecular bricks are H bond interactions (diyne-H···O=C or halogen bond interactions (diyne-Br···O=C, respectively. Based on crystallographic atom coordinates, DFT (B3LYP/6-31++G(d,p and DFT (M06-2X/6-31++G(d,p calculations were performed on these isostructural crystals to gain insight into the intermolecular interactions.

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.

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

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.

Die Interhalogenkationen [Br2F5]+ und [Br3F8].

Science.gov (United States)

Ivlev, Sergei; Karttunen, Antti; Buchner, Magnus; Conrad, Matthias; Kraus, Florian

2018-05-02

Wir berichten über die Synthese und Charakterisierung der bislang einzigen Polyhalogenkationen, in denen verbrückende Fluoratome vorliegen. Das [Br2F5]+-Kation enthält eine symmetrische [F2Br-µ-F-BrF2]-Brücke, das [Br3F8]+-Kation enthält unsymmetrische µ-F-Brücken. Die Fluoronium-Ionen wurden in Form ihrer [SbF6]--Salze erhalten und Raman-, und 19F-NMR-spektroskopisch, sowie durch Röntgenbeugung am Einkristall untersucht. Quantenchemische Rechnungen, sowohl für die isolierten Kationen in der Gasphase, als auch für die Festkörper selbst, wurden durchgeführt. Populationsanalysen zeigen, dass die µ-F-Atome die am stärksten negativ partialgeladenen Atome der Kationen sind. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Making a robust carbon-cobalt(III) bond

DEFF Research Database (Denmark)

Larsen, Erik; Madsen, Anders Østergaard; Kofod, Pauli

2009-01-01

The coordination ion with a well-characterized carbon-cobalt(III) bond, the (1,4,7-triazacyclononane)(1,6-diamino-3-thia-4-hexanido)cobalt(III) dication, [Co(tacn)(C-aeaps)](2+) (aeaps, for aminoethylaminopropylsulfide), has been reacted with iodomethane, and the S-methyl thionium derivative has...... been isolated. The crystal structure of the resulting [Co(tacn)(C-aeaps-SCH(3))]Br(3) x 3 H(2)O at 122 K has been determined by X-ray diffraction techniques to verify the structure. The crystal structure determination shows that the carbon-cobalt bond length is even shorter (2.001(4) A) than in [Co......(tacn)(C-aeaps)](2+) participates in bonding to cobalt(III), having implications for the transformation between the carbon- and sulfur-bound forms of the aeaps ligand....

Matrix isolation and computational study of isodifluorodibromomethane (F2CBr-Br): a route to Br2 formation in CF2Br2 photolysis.

Science.gov (United States)

George, Lisa; Kalume, Aimable; El-Khoury, Patrick Z; Tarnovsky, Alexander; Reid, Scott A

2010-02-28

The photolysis products of dibromodifluoromethane (CF(2)Br(2)) were characterized by matrix isolation infrared and UV/Visible spectroscopy, supported by ab initio calculations. Photolysis at wavelengths of 240 and 266 nm of CF(2)Br(2):Ar samples (approximately 1:5000) held at approximately 5 K yielded iso-CF(2)Br(2) (F(2)CBrBr), a weakly bound isomer of CF(2)Br(2), which is characterized here for the first time. The observed infrared and UV/Visible absorptions of iso-CF(2)Br(2) are in excellent agreement with computational predictions at the B3LYP/aug-cc-pVTZ level. Single point energy calculations at the CCSD(T)/aug-cc-pVDZ level on the B3LYP optimized geometries suggest that the isoform is a minimum on the CF(2)Br(2) potential energy surface, lying some 55 kcal/mol above the CF(2)Br(2) ground state. The energies of various stationary points on the CF(2)Br(2) potential energy surface were characterized computationally; taken with our experimental results, these show that iso-CF(2)Br(2) is an intermediate in the Br+CF(2)Br-->CF(2)+Br(2) reaction. The photochemistry of the isoform was also investigated; excitation into the intense 359 nm absorption band resulted in isomerization to CF(2)Br(2). Our results are discussed in view of the rich literature on the gas-phase photochemistry of CF(2)Br(2), particularly with respect to the existence of a roaming atom pathway leading to molecular products.

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.

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

Core electron binding energy shifts of AlBr3 and Al2Br6 vapor

International Nuclear Information System (INIS)

Mueller, Astrid M.; Plenge, Juergen; Leone, Stephen R.; Canton, Sophie E.; Rude, Bruce S.; Bozek, John D.

2006-01-01

The Al 2p and Br 3d inner-shell photoelectron spectra of aluminum tribromide monomer and dimer vapor were measured at 90 and 95 eV photon energy, respectively, to determine the core electron binding energies of the atoms in the two molecular species. While AlBr 3 has three identical Br atoms, Al 2 Br 6 exhibits four terminal and two bridging Br atoms. The species are identified by their distinct valence photoelectron spectra. Comparison of the observed Al 2p 1/2 and Al 2p 3/2 electron binding energies of AlBr 3 with those of Al 2 Br 6 shows that there is a chemical shift of (0.15 ± 0.03) eV to lower energy in the dimer. In Al 2 Br 6 , an assignment is proposed in which the Br 3d 3/2 and Br 3d 5/2 binding energies of terminal Br atoms are (1.18 ± 0.03) eV lower than those of bridging Br atoms. This assignment assumes that both types of Br atoms have similar cross-sections for ionization. With this result, the Br 3d 3/2 and Br 3d 5/2 binding energies of Br atoms in AlBr 3 are (0.81 ± 0.03) eV lower than those of bridging Br atoms of the dimer but (0.37 ± 0.03) eV higher than those of terminal Br atoms of the dimer. The obtained chemical shifts are considered in terms of the binding relations and electron density distributions in both molecules. Chemical shifts that are larger than a few hundred millielectron volts, as observed in the Al 2 Br 6 /AlBr 3 system, offer potential to study the dissociation dynamics of the dimer in a femtosecond visible or ultraviolet-pump/XUV-probe experiment

Electronic dipole moment and tunneling state of hydrogen atom in hydrogen-bond materials revealed by neutron and X-ray structure analyses

International Nuclear Information System (INIS)

Kiyanagi, Ryoji; Noda, Yukio; Mochida, Tomoyuki; Sugawara, Tadashi

2007-01-01

The isolated hydrogen-bonded materials, 5-methyl-9-hydroxyphenalenone (MeHPLN) and 5-bromo-9-hydroxyphenalenone (Br-HPLN), were studied by means of X-ray and neutron diffraction methods. It was found that the position of the nucleus of the hydrogen atom in the hydrogen-bond region does not agree with the center of mass of the electron cloud of the hydrogen atom. This leads to a local electronic dipole moment in the hydrogen-bond region. Using the experimentally obtained dipole moment, phase transition temperatures for MeHPLN and BrHPLN were calculated based on a tunneling model. Result shows good agreement with the ones obtained by a dielectric measurement. (author)

The first report of a muoniated free radical formed from reaction of Mu with Br2

International Nuclear Information System (INIS)

Ghandi, Khashayar; Cottrell, Stephen P.; Fleming, Donald; Johnson, Clive

2006-01-01

In this paper, we report preliminary data for the first direct evidence of a free radical formed from Mu reactivity with Br 2 in the gas phase, in N 2 moderator at a total pressure of 3 bar. A new experimental setup and target vessel for μSR studies of reactive compounds, such as the halogens and hydrogen halides, suitable as well for RF measurements, is described. The experimental data, obtained from a longitudinal field repolarization curve, yields a hfc of 1770 MHz. We tentatively identify this as the [BrMuBr] radical, a non-conventional bond system, arising from the combination of a van der Waals interaction and dynamics on a repulsive surface. Studies of the dynamics and hfcs of possible radicals, which in principal could form, are also outlined here

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

Matrix isolation and computational study of isodifluorodibromomethane (F2CBr-Br): A route to Br2 formation in CF2Br2 photolysis

International Nuclear Information System (INIS)

George, Lisa; Kalume, Aimable; Reid, Scott A.; El-Khoury, Patrick Z.; Tarnovsky, Alexander

2010-01-01

The photolysis products of dibromodifluoromethane (CF 2 Br 2 ) were characterized by matrix isolation infrared and UV/Visible spectroscopy, supported by ab initio calculations. Photolysis at wavelengths of 240 and 266 nm of CF 2 Br 2 :Ar samples (∼1:5000) held at ∼5 K yielded iso-CF 2 Br 2 (F 2 CBrBr), a weakly bound isomer of CF 2 Br 2 , which is characterized here for the first time. The observed infrared and UV/Visible absorptions of iso-CF 2 Br 2 are in excellent agreement with computational predictions at the B3LYP/aug-cc-pVTZ level. Single point energy calculations at the CCSD(T)/aug-cc-pVDZ level on the B3LYP optimized geometries suggest that the isoform is a minimum on the CF 2 Br 2 potential energy surface, lying some 55 kcal/mol above the CF 2 Br 2 ground state. The energies of various stationary points on the CF 2 Br 2 potential energy surface were characterized computationally; taken with our experimental results, these show that iso-CF 2 Br 2 is an intermediate in the Br+CF 2 Br→CF 2 +Br 2 reaction. The photochemistry of the isoform was also investigated; excitation into the intense 359 nm absorption band resulted in isomerization to CF 2 Br 2 . Our results are discussed in view of the rich literature on the gas-phase photochemistry of CF 2 Br 2 , particularly with respect to the existence of a roaming atom pathway leading to molecular products.

Computer simulation of the structure of liquid metal halides RbBr, CuCl, CuBr, CuI, and AgBr

International Nuclear Information System (INIS)

Belashchenko, D.K.; Ostrovskij, O.I.

2003-01-01

The computerized models of the RbBr, AgBr, CuCl, CuBr and CuI liquid ion systems of 498 ions dimension are simulated at the temperatures of 753-960 K on the basis of the known diffraction data through the BELION algorithm. Good agreement of diffraction and model partial pair correlation functions (PPCF), excluding the PPCF first peaks heights, is obtained in all the cases. The simulation is carried out by the varied ion charges (the atomization energy values, close to the real ones, are obtained by ion charges ±1.00 for the RbBr, ±1.15 for AgBr, ±1.20 for CuCl, ±1.48 for CuBr and ±1.367 for CuI). The noncoulomb contributions in the interparticle potentials are calculated [ru

Syntheses, structures and redox properties of some complexes containing the Os(dppe)Cp* fragment, including [{Os(dppe)Cp*}2(mu-C triple bondCC triple bond C)].

Science.gov (United States)

Bruce, Michael I; Costuas, Karine; Davin, Thomas; Halet, Jean-François; Kramarczuk, Kathy A; Low, Paul J; Nicholson, Brian K; Perkins, Gary J; Roberts, Rachel L; Skelton, Brian W; Smith, Mark E; White, Allan H

2007-12-14

The sequential conversion of [OsBr(cod)Cp*] (9) to [OsBr(dppe)Cp*] (10), [Os([=C=CH2)(dppe)Cp*]PF6 ([11]PF6), [Os(C triple bond CH)(dppe)Cp*] (12), [{Os(dppe)Cp*}2{mu-(=C=CH-CH=C=)}][PF6]2 ([13](PF6)2) and finally [{Os(dppe)Cp*}(2)(mu-C triple bond CC triple bond C)] (14) has been used to make the third member of the triad [{M(dppe)Cp*}2(mu-C triple bond CC triple bond C)] (M = Fe, Ru, Os). The molecular structures of []PF6, 12 and 14, together with those of the related osmium complexes [Os(NCMe)(dppe)Cp*]PF6 ([15]PF6) and [Os(C triple bond CPh)(dppe)Cp*] (16), have been determined by single-crystal X-ray diffraction studies. Comparison of the redox properties of 14 with those of its iron and ruthenium congeners shows that the first oxidation potential E1 varies as: Fe approximately Os < Ru. Whereas the Fe complex has been shown to undergo three sequential 1-electron oxidation processes within conventional electrochemical solvent windows, the Ru and Os compounds undergo no fewer than four sequential oxidation events giving rise to a five-membered series of redox related complexes [{M(dppe)Cp*}2(mu-C4)]n+ (n = 0, 1, 2, 3 and 4), the osmium derivatives being obtained at considerably lower potentials than the ruthenium analogues. These results are complimented by DFT and DT DFT calculations.

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.

Rate constant for the reaction SO + BrO yields SO2 + Br

Science.gov (United States)

Brunning, J.; Stief, L.

1986-01-01

The rate of the radical-radical reaction SO + BrO yields SO2 + Br has been determined at 298 K in a discharge flow system near 1 torr pressure with detection of SO and BrO via collision-free sampling mass spectrometry. The rate constant was determined using two different methods: measuring the decay of SO radicals in the presence of an excess of BrO and measuring the decay of BrO radicals in excess SO. The results from the two methods are in reasonable agreement and the simple mean of the two values gives the recommended rate constant at 298 K, k = (5.7 + or - 2.0) x 10 to the -11th cu cm/s. This represents the first determination of this rate constant and it is consistent with a previously derived lower limit based on SO2 formation. Comparison is made with other radical-radical reactions involving SO or BrO. The reaction SO + BrO yields SO2 + Br is of interest for models of the upper atmosphere of the earth and provides a potential coupling between atmospheric sulfur and bromine chemistry.

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

Use of paired, bonded NdFeB magnets in redox magnetohydrodynamics.

Science.gov (United States)

Arumugam, Prabhu U; Clark, Emily A; Fritsch, Ingrid

2005-02-15

Bonded neodymium-iron-boron (NdFeB) permanent magnets in a paired configuration were successfully used to control mass transport in redox-based, magnetohydrodynamics (MHD). Control of fluid flow based on magnetic fields has potential for use in portable lab-on-a-chip (LOAC) and analytical devices. Bonded magnets, composed of magnetic powder and organic binder materials, are less expensive and easier to fabricate and pattern than electromagnets and sintered permanent magnets, which have been previously used in MHD studies on electrochemical systems. The ability to pattern bonded magnets near and around the electrodes is expected to allow for better control over the magnetic field distribution and solution flow. Current was generated at an 800-microm-radius platinum disk electrode in a solution of 0.06 M nitrobenzene and 0.5 M tetra-n-butylammonium hexafluorophosphate in acetonitrile. Increases in limiting current in the presence of the magnetic field, which indicate enhancement in mass transport, for sintered (210+/-14%, N = 4, where B(r) = 1.23 T and magnetic field strength is 0.55 T) and bonded (94+/-8%, N = 4, where B(r) = 0.41 T and magnetic field strength is 0.20 T) magnets, were similar to those obtained using an electromagnet with the same magnetic flux densities. The magnetic field strength and not the magnet type is important in controlling fluid flow, which is encouraging for integration of bonded permanent magnets into LOAC devices.

Photodissociation of C3H5Br and C4H7Br at 234 nm

International Nuclear Information System (INIS)

Kim, Hyun Kook; Paul, Dababrata; Hong, Ki Ryong; Cho, Ha Na; Kim, Tae Kyu; Lee, Kyoung Seok

2012-01-01

The photodissociation dynamics of cyclopropyl bromide (C-3H 5 Br) and cyclobutyl bromide (C 4 H 7 Br) at 234 nm was investigated. A two-dimensional photofragment ion-imaging technique coupled with a [2+1] resonance enhanced multiphoton ionization scheme was utilized to obtain speed and angular distributions of the nascent Br( 2 P 3/2 ) and Br*( 2 P 1/2 ) atoms. The recoil anisotropies for the Br and Br* channels were measured to be βBr = 0.92 ± 0.03 and βBr* = 1.52 ± 0.04 for C 3 H 5 Br and βBr = 1.10 ± 0.03 and βBr* = 1.49 ± 0.05 for C 4 H 7 Br. The relative quantum yield for Br was found to be ΦBr = 0.13 ± 0.03 and for C 3 H 5 Br and C 4 H 7 Br, respectively. The soft radical limit of the impulsive model adequately modeled the related energy partitioning. The nonadiabatic transition probability from the 3A' and 4A' potential energy surfaces was estimated and discussed

Nonadiabatic quantum dynamics and laser control of Br2 in solid argon.

Science.gov (United States)

Accardi, A; Borowski, A; Kühn, O

2009-07-02

A five-dimensional reaction surface-vibronic coupling model is introduced to describe the B- to C-state predissociation dynamics of Br(2) occupying a double substitutional lattice site in a face-centered cubic argon crystal at low temperatures. The quantum dynamics driven by a Franck-Condon vertical excitation is investigated, revealing the role of matrix cage compression for efficient nonadiabatic transitions. Vibrational preexcitation of the Br(2) bond in the electronic ground state can be used to access a different regime of predissociation which does not require substantial matrix compression because the Franck-Condon window shifts into the energetic range of the B-C level crossing. Using optimal control theory, it is shown how vibrational preexcitation can be achieved via a pump-dump-type mechanism involving the repulsive C state.

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

Tetrabromido[4-(triphenylphosphanyloxybutyl]tellurium acetonitrile monosolvate

Directory of Open Access Journals (Sweden)

Sari M. Närhi

2013-02-01

Full Text Available In the title compound, [TeBr4(C22H23OP]·CH3CN, the Te atom exhibits a square-pyramidal coordination with an apical Te—C bond and four basal Te—Br bonds. The conformation of the aliphatic C—C—C—C chain is gauche [torsion angle = −67.7 (8°]. A weak C—H...Br interaction helps to establish the conformation. In the crystal, there is a weak secondary bonding interaction [Te...N = 3.456 (11 Å] between the Te atom and the N atom of the solvent molecule, which completes a distorted TeNCBr4 octahedron. Inversion dimers linked by pairs of C—H...Br interactions are also observed.

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

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

Imaging the Dynamics of CH2BrI Photodissociation in the Near Ultraviolet Region.

Science.gov (United States)

Pan, Changen; Zhang, Yi; Lee, Joseph D; Kidwell, Nathanael M

2018-04-19

The photodissociation dynamics of jet-cooled CH 2 BrI were investigated in the near-ultraviolet (UV) region from 280-310 nm using velocity map imaging. We report the translational and internal energy distributions of the CH 2 Br radical and ground state I ( 2 P 3/2 ) or spin-orbit excited I ( 2 P 1/2 ) fragments determined by velocity map imaging of the ionized iodine fragments following 2 + 1 resonance-enhanced multiphoton ionization of the nascent neutral iodine products. The velocity distributions indicate that most of the available energy is partitioned into the internal energy of the CH 2 Br radical with only modest translational excitation imparted to the cofragments, which is consistent with a simple impulsive model. Furthermore, from extrapolation of the velocity distribution results, the first determination of the C-I bond dissociation energy of CH 2 BrI is presented in this work to be D 0 = 16 790 ± 590 cm -1 . The ion images appear anisotropic, indicative of a prompt dissociation, and the derived anisotropy parameters are consistently positive. Additionally, the angular distributions report on the electronic excited state dynamics, which validate recent works characterizing the electronic states responsible for the first absorption band of CH 2 BrI. In the current work, photolysis of CH 2 BrI on the red edge of the absorption spectrum reveals an additional channel producing I ( 2 P 3/2 ) fragments.

Energetic Diagrams and Structural Properties of Monohaloacetylenes HC≡CX (X = F, Cl, Br).

Science.gov (United States)

Khiri, D; Hochlaf, M; Chambaud, G

2016-08-04

Highly correlated electronic wave functions within the Multi Reference Configuration Interaction (MRCI) approach are used to study the stability and the formation processes of the monohaloacetylenes HCCX and monohalovinylidenes C2HX (X = F, Cl, Br) in their electronic ground state. These tetra-atomics can be formed through the reaction of triatomic fragments C2F, C2Cl, and C2Br with a hydrogen atom or of C2H with halogen atoms via barrierless reactions, whereas the reactions between the diatomics [C2 + HX] need to overcome barriers of 1.70, 0.89, and 0.58 eV for X = F, Cl, and Br. It is found that the linear HCCX isomers, in singlet symmetry, are more stable than the singlet C2HX iso-forms by 1.995, 2.083, and 1.958 eV for X = F, Cl, and Br. The very small isomerization barriers from iso to linear forms are calculated 0.067, 0.044, and 0.100 eV for F, Cl, and Br systems. The dissociation energies of the HCCX systems (without ZPE corrections), resulting from the breaking of the CX bond, are calculated to be 5.647, 4.691, and 4.129 eV for X = F, Cl, Br, respectively. At the equilibrium geometry of the X(1)Σ(+) state of HCCX, the vertical excitation energies in singlet and triplet symmetries are all larger than the respective dissociation energies. Stable excited states are found only as (3)A', (3)A″, and (1)A″ monohalovinylidene structures.

Pressure-Induced Structural and Optical Properties of Inorganic Halide Perovskite CsPbBr3.

Science.gov (United States)

Zhang, Long; Zeng, Qingxin; Wang, Kai

2017-08-17

Perovskite photovoltaic materials are gaining sustained attention because of their excellent photovoltaic properties and extensive practical applicability. In this Letter, we discuss the changes in the structure and optical properties of CsPbBr 3 under high pressure. As the pressure increased, the band gap initially began to red shift before 1.0 GPa followed by a continuous blue shift until the crystal was completely amorphized. An isostructural phase transition at 1.2 GPa was determined by high-pressure synchrotron X-ray and Raman spectroscopy. The result could be attributed to bond length shrinkage and PbBr 6 octahedral distortion under high pressure. The amorphization of the crystal was due to the severe distortion and tilt of the PbBr 6 octahedron, leading to broken long-range order. Changes in optical properties are closely related to the evolution of the crystal structure. Our discussion shows that high-pressure study can be used as an effective means to tune the structure and properties of all-inorganic halide perovskites.

Brazilian Validation of the Attachment to God Inventory (IAD-Br

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Hartmut August

2018-03-01

Full Text Available Bowlby’s Attachment Theory proposes that the person seeks protection and security with his or her caregiver, establishing a significant bond, which Bowlby characterizes as “attachment relationship”. The relationship with God can also be understood as an attachment relationship. Until now, there are no instruments in Brazil to measure one’s attachment to God. The purpose of this article is to present the adaptation and validation process of the Attachment to God Inventory for the Brazilian context, resulting in a Brazilian version of the Attachment to God Inventory (IAD-Br. The validation methodology for the IAD-Br consisted of Portuguese translation, reverse translation to English, pre-test, data collection, and validation through confirmatory factorial analysis (CFA. A total of 470 people participated in the study: 179 men and 291 women. Confirmatory factorial analysis presented unsatisfactory statistical parameters. Of the 28 items of the instrument, 11 items did not present adequate Item-Total Correlation. After excluding these 11 items, the instrument presented adequate adjustment indices. The IAD-Br, composed of 17 items, is able to be used to measure attachment to God in Brazil and constitutes a relevant instrument to identify the attachment to God style, being useful for application in the psychotherapeutic clinic and in contexts of spiritual care.

Synthesis and Crystal Structure of a Three—dimensionla Manganese（Ⅱ）Complex COnstructed via Covalent and Hydrogen Bonds

Institute of Scientific and Technical Information of China (English)

WANGRui－Hu; ChenLi－Hua; 等

2003-01-01

The assembly of 1,4-benzenedicarboxylic acid (H2bdc),4,4′-bipyridine (4,4′-bipy),trimethyltin chloride and MnBr2.4H2O in hydrothermal conditions gave rise to a hydrogen-bonded three-dimensional complex {Mn(4,4′-bipy).4H2O](bdc}nwhich has been characterized by single-crystal X-ray diffraction.The complex crystallizes in the monoclinic system,space group,P2/n with a=7.0001(2),b=11.5540(3),c=11.4192(1)°↑A,β=101.754(2)°,V=904.21(4)°↑A3,Z=2,C18H20MnN2O8,Mr=447.30,Dc=1.643 g/cm3,F(000)=462 and μ（Mokα)=0.783mm1,The final R and wR are 0.0499 and 0.1301,respectively for 1335 observed reflctions with I≥2σ（I）.The Mn（Ⅱ）is six-coordinated in a distorted octahedral geometry,4,4′-Bipyridine in a μ-bridge mode links [Mn(H2O)4]2+ into a linear cation chain.bdc acts as a counter anion and links the linear chains into a three-dimensional structure through hydrogen bonds.

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

Angular correlation for gamma-gamma transitions in 81Br and 83Br nuclei

International Nuclear Information System (INIS)

Matheus, R.

1984-01-01

The directional angular correlation of coincident gamma transitions in 81 Br and 83 Br have been measured following the β - decay of 81 Se(T sub(1/2) = 18.6 min) and 83 Se(T sub(1/2) = 22.6 min) respectively, using Ge(Li) - high purity Ge and Ge(Li)-NaI(Tl) spectrometers. The radioactive sources were prepared by irradiating with neutrons in the IEA-R1 reactor, metallic selenium (natural) to produce 81 Se and samples of metallic selenium enriched (to approx. 90% in 82 Se) to produce 83 Se. Measurements have been carried out for the gamma cascades 260-276 KeV, 290-276 KeV and 552-276 KeV in 81 Br and the gamma cascades 225(510)-356 KeV, 510-356 KeV, 572-(510)-356 KeV, 718-(225)-(510)-356 KeV, 1064-356 KeV, 718-225 KeV, 718-(225)-510 KeV, 836-718 KeV, 718-(225)-866 KeV, 883-718 KeV and 1895-799 KeV in 83 Br. The multipole mixing ratios, σ(E2/M1), were determined for 3 gamma transitions in 81 Br and 11 gamma transitions in 83 Br. In the case of 81 Br present results confirmed some of the earlier results. The spin and parity assignment were made to the majority of levels in 81 Br and 83 Br involved in the present study, some of them confirming the earlier results. A comparison of some of the nuclear properties of the 79 Br, 81 Br and 83 Br is made based on the available experimental data. The experimental results are also discussed qualitatively in terms of some nuclear models applicable for the description of the properties of odd-A bromine isotopes. (Author) [pt

The first report of a muoniated free radical formed from reaction of Mu with Br{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Ghandi, Khashayar [Department of Chemistry, Mount Allison University, 63C York Street, Sackville (Canada)]. E-mail: kghandi@mta.ca; Cottrell, Stephen P. [ISIS, CCLRC Rutherford Appleton Laboratory, Chilton (United Kingdom); Fleming, Donald [Department of Chemistry, University of British Columbia and TRIUMF, Vancouver, NB E4L 1G8 (Canada); Johnson, Clive [ISIS, CCLRC Rutherford Appleton Laboratory, Chilton (United Kingdom)

2006-03-31

In this paper, we report preliminary data for the first direct evidence of a free radical formed from Mu reactivity with Br{sub 2} in the gas phase, in N{sub 2} moderator at a total pressure of 3 bar. A new experimental setup and target vessel for {mu}SR studies of reactive compounds, such as the halogens and hydrogen halides, suitable as well for RF measurements, is described. The experimental data, obtained from a longitudinal field repolarization curve, yields a hfc of 1770 MHz. We tentatively identify this as the [BrMuBr] radical, a non-conventional bond system, arising from the combination of a van der Waals interaction and dynamics on a repulsive surface. Studies of the dynamics and hfcs of possible radicals, which in principal could form, are also outlined here.

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 ...

$^{80}$Br $^{80}$Br-a new electron-gamma PAC probe

CERN Document Server

Correia, J G; Araújo, J P; Marques, J G; Soares, J C; Melo, A A

2001-01-01

Conversion electron-gamma PAC measurements of the 49-37 keV cascade in /sup 80/Br through the intermediate 2/sup -/ state with T/sub 1/2 /=7.4 ns were performed with a system of two magnetic lens spectrometers and two BaF/sub 2/ scintillation detectors. The parent /sup 80m/Br activity with a halflife of 4.4 hrs was implanted into Ni, Zn and graphite at the ISOLDE separator at CERN. The observed interaction frequency in the nickel matrix is in good agreement with the known value of the hyperfine field for Br in Ni and the magnetic moment of the 2/sup -/ state. From the measured quadrupole interaction in Zn and graphite the electric field gradients at Br were obtained. (7 refs).

Preparation of 80Br or 82Br-biomolecules via excitation labelling methods

International Nuclear Information System (INIS)

Wong, S.; Ache, H.J.

1975-01-01

The direct decay-induced 82 Br (or 80 Br) labelling by exposing the solid substrate molecules, such as deoxyuridine, L-tyrosine, guanosine, deoxycytidine, phenylalanine, and acetic acid, to gaseous CF 3 82 /sup m/Br (or CF 3 80 /sup m/Br) was studied. The radiochemical yields of the brominated products are relatively small and range from 1 percent in the case of bromo deoxyuridine to 11 percent for bromoacetic acid. The modification of this technique by adding Cl 2 gas to the reaction mixture improves the yields in several cases drastically (up to 80 percent for bromo-guanosine and bromo-L-tyrosine). Similar improvement can be achieved by exposing crystalline KBrO 3 for some time to CF 3 82 /sup m/Br (or CF 3 80 /sup m/Br) and dissolving subsequently the KBrO 3 in an acidic solution of the substrate. (auth)

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

Metathesis Polymerization Reactions Induced by the Bimetallic Complex (Ph4P2[W2(μ-Br3Br6

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Despoina Chriti

2015-12-01

Full Text Available The reactivity of the bimetallic complex (Ph4P2[W2(μ-Br3Br6] ({W 2.5 W}7+, a′2e3 towards ring opening metathesis polymerization (ROMP of norbornene (NBE and some of its derivatives, as well as the mechanistically related metathesis polymerization of phenylacetylene (PA, is presented. Our results show that addition of a silver salt (AgBF4 is necessary for the activation of the ditungsten complex. Polymerization of PA proceeds smoothly in tetrahydrofuran (THF producing polyphenylacetylene (PPA in high yields. On the other hand, the ROMP of NBE and its derivatives is more efficient in CH2Cl2, providing high yields of polymers. 13C Cross Polarization Magic Angle Spinning (CPMAS spectra of insoluble polynorbornadiene (PNBD and polydicyclopentadiene (PDCPD revealed the operation of two mechanisms (metathetic and radical for cross-linking, with the metathesis pathway prevailing.

Et2NH2C6H3(CO23SnBr2.4H2O: SYNTHESIS AND INFRARED STUDY

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DAOUDA NDOYE

2014-01-01

Full Text Available The title compound has been obtained on allowing [C6H3(CO23(Et2NH23] to react with SnBr4. The molecular structure of Et2NH2C6H3(CO23SnBr2.4H2O has been determined on the basis of the infrared data. The suggested structure is a dimer in which each tin atom is hexacoordinated by two chelating C6H3(CO233- anions and two Br atoms. Cy2NH2+cations are involved through hydrogen bonds with non-coordinating CO2 groups. The suggested structure is a cage.

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.

Novel technique for spatially resolved imaging of molecular bond orientations using x-ray birefringence

Energy Technology Data Exchange (ETDEWEB)

Sutter, John P., E-mail: john.sutter@diamond.ac.uk; Dolbnya, Igor P.; Collins, Stephen P. [Diamond Light Source Ltd, Harwell Science and Innovation Campus, Chilton, Didcot, Oxfordshire OX11 0DE (United Kingdom); Harris, Kenneth D. M., E-mail: HarrisKDM@cardiff.ac.uk; Edwards-Gau, Gregory R.; Kariuki, Benson M. [School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT (United Kingdom); Palmer, Benjamin A. [Department of Structural Biology, Weizmann Institute of Science, 234 Herzl St., Rehovot 7610001 (Israel)

2016-07-27

Birefringence has been observed in anisotropic materials transmitting linearly polarized X-ray beams tuned close to an absorption edge of a specific element in the material. Synchrotron bending magnets provide X-ray beams of sufficiently high brightness and cross section for spatially resolved measurements of birefringence. The recently developed X-ray Birefringence Imaging (XBI) technique has been successfully applied for the first time using the versatile test beamline B16 at Diamond Light Source. Orientational distributions of the C–Br bonds of brominated “guest” molecules within crystalline “host” tunnel structures (in thiourea or urea inclusion compounds) have been studied using linearly polarized incident X-rays near the Br K-edge. Imaging of domain structures, changes in C–Br bond orientations associated with order-disorder phase transitions, and the effects of dynamic averaging of C–Br bond orientations have been demonstrated. The XBI setup uses a vertically deflecting high-resolution double-crystal monochromator upstream from the sample and a horizontally deflecting single-crystal polarization analyzer downstream, with a Bragg angle as close as possible to 45°. In this way, the ellipticity and rotation angle of the polarization of the beam transmitted through the sample is measured as in polarizing optical microscopy. The theoretical instrumental background calculated from the elliptical polarization of the bending-magnet X-rays, the imperfect polarization discrimination of the analyzer, and the correlation between vertical position and photon energy introduced by the monochromator agrees well with experimental observations. The background is calculated analytically because the region of X-ray phase space selected by this setup is sampled inefficiently by standard methods.

Crystal structures of dibromido{N-[(pyridin-2-yl-κNmethylidene]picolinohydrazide-κ2N′,O}cadmium methanol monosolvate and diiodido{N-[(pyridin-2-yl-κNmethylidene]picolinohydrazide-κ2N′,O}cadmium

Directory of Open Access Journals (Sweden)

Ali Akbar Khandar

2017-05-01

Full Text Available The title compounds, [CdBr2(C12H10N4O]·CH3OH, (I, and [CdI2(C12H10N4O], (II, are cadmium bromide and cadmium iodide complexes of the ligand (E-N′-(pyridin-2-ylmethylenepicolinohydrazide. Complex (I crystallizes as the methanol monosolvate. In both compounds, the Cd2+ cation is ligated by one O atom and two N atoms of the tridentate ligand, and by two bromide anions forming a Br2N2O pentacoordination sphere for (I, and by two iodide anions forming an I2N2O pentacoordination sphere for (II, both with a distorted square-pyramidal geometry. In the crystal of complex (I, molecules are linked by pairs of N—H...O and O—H...Br hydrogen bonds, involving the solvent molecule, forming dimeric units, which are linked by C—H...Br hydrogen bonds forming layers parallel to (101. In the crystal of complex (II, molecules are linked by N—H...I hydrogen bonds, forming chains propagating along [010]. In complex (II, measured at room temperature, the two iodide anions are each disordered over two sites; the refined occupancy ratio is 0.75 (2:0.25 (2.

RESONANCE CARS IN BR2 MOLECULES AND BR-ATOMS

NARCIS (Netherlands)

Aben, I.; Levelt, P.; Ubachs, W.M.G.; Hogervorst, W.

1991-01-01

Resonance-enhanced CARS processes were studied in molecular bromine. On the basis of the known spectroscopic constants of the two electronic states involved, the features in the spectra could be identified. CARS signals from Br-atoms produced from dissociation of Br2 were obtained by tuning (omega-1

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

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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

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).

Haloacyl complexes of boron, [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I).

Science.gov (United States)

Finze, Maik; Bernhardt, Eduard; Willner, Helge; Lehmann, Christian W

2005-11-04

The haloacyltris(trifluoromethyl)borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been synthesized by reacting (CF3)3BCO with either MHal (M=K, Cs; Hal=F) in SO2 or MHal (M=[nBu4N]+, [Et4N]+, [Ph4P]+; Hal=Cl, Br, I) in dichloromethane. Metathesis reactions of the fluoroacyl complex with Me3SiHal (Hal=Cl, Br, I) led to the formation of its higher homologues. The thermal stabilities of the haloacyltris(trifluoromethyl)borates decrease from the fluorine to the iodine derivative. The chemical reactivities decrease in the same order as demonstrated by a series of selected reactions. The new [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br) salts are used as starting materials in the syntheses of novel compounds that contain the (CF3)3B-C fragment. All borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been characterized by multinuclear NMR spectroscopy (11B, 13C, 17O, 19F) and vibrational spectroscopy. [PPh4][(CF3)3BC(O)Br] crystallizes in the monoclinic space group P2/c (no. 13) and the bond parameters are compared with those of (CF3)3BCO and K[(CF3)3BC(O)F]. The interpretation of the spectroscopic and structural data are supported by DFT calculations [B3LYP/6-311+G(d)].

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.)

Molecular elimination of Br2 in photodissociation of CH2BrC(O)Br at 248 nm using cavity ring-down absorption spectroscopy.

Science.gov (United States)

Fan, He; Tsai, Po-Yu; Lin, King-Chuen; Lin, Cheng-Wei; Yan, Chi-Yu; Yang, Shu-Wei; Chang, A H H

2012-12-07

The primary elimination channel of bromine molecule in one-photon dissociation of CH(2)BrC(O)Br at 248 nm is investigated using cavity ring-down absorption spectroscopy. By means of spectral simulation, the ratio of nascent vibrational population in v = 0, 1, and 2 levels is evaluated to be 1:(0.5 ± 0.1):(0.2 ± 0.1), corresponding to a Boltzmann vibrational temperature of 581 ± 45 K. The quantum yield of the ground state Br(2) elimination reaction is determined to be 0.24 ± 0.08. With the aid of ab initio potential energy calculations, the obtained Br(2) fragments are anticipated to dissociate on the electronic ground state, yielding vibrationally hot Br(2) products. The temperature-dependence measurements support the proposed pathway via internal conversion. For comparison, the Br(2) yields are obtained analogously from CH(3)CHBrC(O)Br and (CH(3))(2)CBrC(O)Br to be 0.03 and 0.06, respectively. The trend of Br(2) yields among the three compounds is consistent with the branching ratio evaluation by Rice-Ramsperger-Kassel-Marcus method. However, the latter result for each molecule is smaller by an order of magnitude than the yield findings. A non-statistical pathway so-called roaming process might be an alternative to the Br(2) production, and its contribution might account for the underestimate of the branching ratio calculations.

Reactor BR2

Energy Technology Data Exchange (ETDEWEB)

Gubel, P

2000-07-01

The BR2 reactor is still SCK-CEN's most important nuclear facility. After an extensive refurbishment to compensate for the ageing of the installation, the reactor was restarted in April 1997. Various aspects concerning the operation of the BR2 Reactor, the utilisation of the CALLISTO loop and the irradiation programme, the BR2 R and D programme and the production of isotopes and of NTD-silicon are discussed. Progress and achievements in 1999 are reported.

Reactor BR2

International Nuclear Information System (INIS)

Gubel, P.

2000-01-01

The BR2 reactor is still SCK-CEN's most important nuclear facility. After an extensive refurbishment to compensate for the ageing of the installation, the reactor was restarted in April 1997. Various aspects concerning the operation of the BR2 Reactor, the utilisation of the CALLISTO loop and the irradiation programme, the BR2 R and D programme and the production of isotopes and of NTD-silicon are discussed. Progress and achievements in 1999 are reported

Hybridization of Single Nanocrystals of Cs4PbBr6 and CsPbBr3.

Science.gov (United States)

Weerd, Chris de; Lin, Junhao; Gomez, Leyre; Fujiwara, Yasufumi; Suenaga, Kazutomo; Gregorkiewicz, Tom

2017-09-07

Nanocrystals of all-inorganic cesium lead halide perovskites (CsPbX 3 , X = Cl, Br, I) feature high absorption and efficient narrow-band emission which renders them promising for future generation of photovoltaic and optoelectronic devices. Colloidal ensembles of these nanocrystals can be conveniently prepared by chemical synthesis. However, in the case of CsPbBr 3 , its synthesis can also yield nanocrystals of Cs 4 PbBr 6 and the properties of the two are easily confused. Here, we investigate in detail the optical characteristics of simultaneously synthesized green-emitting CsPbBr 3 and insulating Cs 4 PbBr 6 nanocrystals. We demonstrate that, in this case, the two materials inevitably hybridize, forming nanoparticles with a spherical shape. The actual amount of these Cs 4 PbBr 6 nanocrystals and nanohybrids increases for synthesis at lower temperatures, i.e., the condition typically used for the development of perovskite CsPbBr 3 nanocrystals with smaller sizes. We use state-of-the-art electron energy loss spectroscopy to characterize nanoparticles at the single object level. This method allows distinguishing between optical characteristics of a pure Cs 4 PbBr 6 and CsPbBr 3 nanocrystal and their nanohybrid. In this way, we resolve some of the recent misconceptions concerning possible visible absorption and emission of Cs 4 PbBr 6 . Our method provides detailed structural characterization, and combined with modeling, we conclusively identify the nanospheres as CsPbBr 3 /Cs 4 PbBr 6 hybrids. We show that the two phases are independent of each other's presence and merge symbiotically. Herein, the optical characteristics of the parent materials are preserved, allowing for an increased absorption in the UV due to Cs 4 PbBr 6 , accompanied by the distinctive efficient green emission resulting from CsPbBr 3 .

The anomalous halogen bonding interactions between chlorine and bromine with water in clathrate hydrates.

Science.gov (United States)

Dureckova, Hana; Woo, Tom K; Udachin, Konstantin A; Ripmeester, John A; Alavi, Saman

2017-10-13

Clathrate hydrate phases of Cl 2 and Br 2 guest molecules have been known for about 200 years. The crystal structure of these phases was recently re-determined with high accuracy by single crystal X-ray diffraction. In these structures, the water oxygen-halogen atom distances are determined to be shorter than the sum of the van der Waals radii, which indicates the action of some type of non-covalent interaction between the dihalogens and water molecules. Given that in the hydrate phases both lone pairs of each water oxygen atom are engaged in hydrogen bonding with other water molecules of the lattice, the nature of the oxygen-halogen interactions may not be the standard halogen bonds characterized recently in the solid state materials and enzyme-substrate compounds. The nature of the halogen-water interactions for the Cl 2 and Br 2 molecules in two isolated clathrate hydrate cages has recently been studied with ab initio calculations and Natural Bond Order analysis (Ochoa-Resendiz et al. J. Chem. Phys. 2016, 145, 161104). Here we present the results of ab initio calculations and natural localized molecular orbital analysis for Cl 2 and Br 2 guests in all cage types observed in the cubic structure I and tetragonal structure I clathrate hydrates to characterize the orbital interactions between the dihalogen guests and water. Calculations with isolated cages and cages with one shell of coordinating molecules are considered. The computational analysis is used to understand the nature of the halogen bonding in these materials and to interpret the guest positions in the hydrate cages obtained from the X-ray crystal structures.

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...

Hydrogen bond nature of ferroelectric material studied by X-ray and neutron diffraction. Electric dipole moment and proton tunneling

International Nuclear Information System (INIS)

Noda, Yukio; Kiyanagi, Ryoji; Mochida, Tomoyuki; Sugawara, Tadashi

2006-01-01

Hydrogen bond nature of MeHPLN and BrHPLN is studied using x-ray and neutron diffraction technique. We found that electric dipole moment of hydrogen atom plays an important role for the phase transition, and proton tunneling model is confirmed on this isolated hydrogen bond system. (author)

The TbBr3–LiBr binary system: Experimental thermodynamic investigation and assessment of phase diagram

International Nuclear Information System (INIS)

Rycerz, L.; Gong, W.; Gaune-Escard, M.

2013-01-01

Highlights: ► DSC measurements for the (LiBr + TbBr 3 ) system. ► congruently Li3TbBr 6 and incongruently melting Li5TbBr 8 compounds. ► Thermodynamic description of the liquid phase in the (LiBr + TbBr 3 ) system. ► Assessment with a two-sublattice ionic solution model. - Abstract: DSC was used to study the phase equilibrium in the TbBr 3 –LiBr binary system. The results obtained provided a basis for constructing the phase diagram of this system. It exhibits two compounds: Li 5 TbBr 8 , which decomposes in the solid state at 611 K, and Li 3 TbBr 6 , which melts congruently at 785 K with the related enthalpy 59.1 kJ·mol −1 . The binary LiBr–TbBr 3 system was then optimized using the available experimental information on phase diagram and thermodynamic properties. A two-sub-lattice ionic solution model (Li + ) P :(Br − , TbBr 6 −3 , TbBr 3 ) Q was adopted to describe the liquid phase. The present assessment of the binary LiBr–TbBr 3 system was in good agreement with the corresponding experimental data and confirmed their consistency.

$^{80m}$Br/$^{80}$Br a new electron-$\\gamma$ - PAC Probe

CERN Document Server

Correia, J G; Araújo, J P; Marques, J G; Soares, J C; Melo, A A

2001-01-01

Conversion electron-$\\gamma$ PAC measurements of the 49 keV - 37 keV cascade in $^{80}$Br through the intermediate 2$^{-}$ state with T$_{1/2}$=7.4 ns were performed with a system of two magnetic lens spectrometers and two BaF$_{2}$ scintillation detectors. The parent $^{80m}$Br activity with half-life of 4.4 hrs was implanted into Ni, Zn and graphite at the ISOLDE separator at CERN. The observed interaction frequency in the nickel matrix is in good agreement with the known value of the hyperfine field for Br in Ni and the magnetic moment of the 2$^{-}$ state. From the measured quadrupole interaction in Zn and graphite the electric field gradients at Br were obtained.

Elimination of nonspecific radioactivity from [76Br]bromide in PET study with [76Br]bromodeoxyuridine

International Nuclear Information System (INIS)

Li Lu; Bergstroem, Mats; Fasth, Karl-Johan; Wu Feng; Eriksson, Barbro; Laangstroem, Bengt

1999-01-01

[ 76 Br]Bromodeoxyuridine ([ 76 Br]BrdU) might allow a determination of proliferation in vivo using positron emission tomography (PET), but only with consideration of organ nonspecific radioactivity constituted by [ 76 Br]bromide. A first study assessed the potential of diuretics to eliminate [ 76 Br]bromide. [ 76 Br]Bromide was injected in the vein of rats and different diuretic combinations were given. Urine was collected and radioactivity measured. Torasemide plus sodium chloride gave better 76 Br elimination than the other diuretics. In a second experiment, rats were given [ 76 Br]BrdU. After the radioactivity injection, the rats of the treatment group were given torasemide plus NaCl. At 44 h after the radioactivity injection, the radioactivity concentration and the fraction incorporated into DNA were measured in different organs. Using diuretics, the elimination of [ 76 Br]bromide was increased. The radioactivity decreased 30-50% in most of the organs but the highest radioactivity uptake was found in the organs with more active DNA synthesis. This method may facilitate the use of [ 76 Br]BrdU as a tracer for DNA synthesis using PET

Global atmospheric model for mercury including oxidation by bromine atoms

Directory of Open Access Journals (Sweden)

C. D. Holmes

2010-12-01

Full Text Available Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg⁰ to Hg^II and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br as an alternative Hg⁰ oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming gas-phase Br to be the sole Hg⁰ oxidant (Hg + Br model and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O₃ model. We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O₃ models, we add an aqueous photochemical reduction of Hg^II in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O₃ models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of Hg^II deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux to the Arctic of 60 Mg a⁻¹. Summertime events of depleted Hg⁰ at Antarctic sites due to subsidence are much better simulated by

Phytoremediation of Hg and Cd from industrial effluents using an aquatic free floating macrophyte Azolla pinnata.

Science.gov (United States)

Rai, Prabhat Kumar

2008-01-01

The level of heavy metal pollution in Singrauli, an industrial region in India, was assessed and the phytoremediation capacity of a small water fern, Azolla pinnata R.BR (Azollaceae), was observed to purify waters polluted by two heavy metals, i.e., mercury (Hg) and cadmium (Cd) under a microcosm condition. Azolla pinnata is endemic to India and is an abundant and easy-growing free-floating water fern usually found in the rice fields, polluted ponds, and reservoirs of India. The fern was grown in 24 40-L aquariums containing Hg2+ and Cd2+ ions each in concentrations of 0.5, 1.0, and 3.0 mgL(-1) during the course of this study. The study revealed an inhibition of Azolla pinnata growth by 27.0-33.9% with the highest in the presence of Hg (II) ions at 0.5 mgL(-1) in comparison to the control After 13 days of the experiment, metal contents in the solution were decreased up to 70-94%. In the tissues of Azolla pinnata, the concentration of selected heavy metals during investigation was recorded between 310 and 740 mgKg(-1) dry mass, with the highest levelfoundfor Cd (II) treatment at 3.0 mgL(-1) containing a metal solution.

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.

Determination of bond energies by mass spectrometry. Some transition metal carbonyls

International Nuclear Information System (INIS)

Michels, G.D.

1979-01-01

Two groups of transition metal carbonyls have been studied, M(CO) 6 and M(CO) 5 CS complexes of the Group VIB metals and M 2 (CO) 10 complexes of the Group VIIB metals. Results for the hexacarbonyl complexes indicate that the measured fragmentation energies are in error by 0.25 +- 0.02 eV per CO produced. This is attributed to excitation of CO to the first vibrational state. Least-squares dissociation energies calculated from corrected data for M(CO) 5 CS complexes indicate that the M--CS bond is 3 to 4 times stronger than the M--CO bonds. Substitution of CS for CO in going from M(CO) 6 to M(CO) 5 CS weakens the remaining M--CO bonds by an average of 0.2 eV. Previously unreported MnTc(CO) 10 and TcRe(CO) 10 are prepared by halide substitution of Tc(CO) 5 Br and Re(CO) 5 Br with Mn(CO) 5 - and Tc(CO) 5 - , respectively. In the positive ion, metal and mixed-metal decacarbonyls are considered as (CO) 5 M + --M(CO) 5 complexes possessing five strong and five weak M--CO bonds. For Mn 2 (CO) 10 and Re 2 (CO) 10 , M + --M dissociation energies are 3.0 +- 0.1 and 4.0 +- 0.3 eV, respectively. These energies are 2.5 times greater than those reported for homolytic cleavage to M(CO) 5 + and M(CO) 5

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)

Improved production of Br atoms near zero speed by photodissociating laser aligned Br2 molecules.

Science.gov (United States)

Deng, L Z; Yin, J P

2014-10-28

We theoretically investigated the improvement on the production rate of the decelerated bromine (Br) atoms near zero speed by photodissociating laser aligned Br2 precursors. Adiabatic alignment of Br2 precursors exposed to long laser pulses with duration on the order of nanoseconds was investigated by solving the time-dependent Schrödinger equation. The dynamical fragmentation of adiabatically aligned Br2 precursors was simulated and velocity distribution of the Br atoms produced was analyzed. Our study shows that the larger the degree of the precursor alignment, ⟨cos(2) θ⟩, the higher the production rate of the decelerated Br atoms near zero speed. For Br2 molecules with an initial rotational temperature of ~1 K, a ⟨cos(2) θ⟩ value of ~0.88 can result in an improvement factor of over ~20 on the production rate of the decelerated Br atoms near zero speed, requiring a laser intensity of only ~1 × 10(12) W/cm(2) for alignment.

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

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.

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

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

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.

All-Ambient Processed Binary CsPbBr3-CsPb2Br5 Perovskites with Synergistic Enhancement for High-Efficiency Cs-Pb-Br-Based Solar Cells.

Science.gov (United States)

Zhang, Xisheng; Jin, Zhiwen; Zhang, Jingru; Bai, Dongliang; Bian, Hui; Wang, Kang; Sun, Jie; Wang, Qian; Liu, Shengzhong Frank

2018-02-28

All-inorganic CsPbBr 3 perovskite solar cells display outstanding stability toward moisture, light soaking, and thermal stressing, demonstrating great potential in tandem solar cells and toward commercialization. Unfortunately, it is still challenging to prepare high-performance CsPbBr 3 films at moderate temperatures. Herein, a uniform, compact CsPbBr 3 film was fabricated using its quantum dot (QD)-based ink precursor. The film was then treated using thiocyanate ethyl acetate (EA) solution in all-ambient conditions to produce a superior CsPbBr 3 -CsPb 2 Br 5 composite film with a larger grain size and minimal defects. The achievement was attributed to the surface dissolution and recrystallization of the existing SCN - and EA. More specifically, the SCN - ions were first absorbed on the Pb atoms, leading to the dissolution and stripping of Cs + and Br - ions from the CsPbBr 3 QDs. On the other hand, the EA solution enhances the diffusion dynamics of surface atoms and the surfactant species. It is found that a small amount of CsPb 2 Br 5 in the composite film gives the best surface passivation, while the Br-rich surface decreases Br vacancies (V Br ) for a prolonged carrier lifetime. As a result, the fabricated device gives a higher solar cell efficiency of 6.81% with an outstanding long-term stability.

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

New measurement of BR(D→ρμν)BR(D→Kμν) branching ratio

Science.gov (United States)

FOCUS Collaboration; Link, J. M.; Yager, P. M.; Anjos, J. C.; Bediaga, I.; Castromonte, C.; Machado, A. A.; Magnin, J.; Massafferri, A.; de Miranda, J. M.; Pepe, I. M.; Polycarpo, E.; Dos Reis, A. C.; Carrillo, S.; Casimiro, E.; Cuautle, E.; Sánchez-Hernández, A.; Uribe, C.; Vá, F.; Agostino, L.; Cinquini, L.; Cumalat, J. P.; O'Reilly, B.; Segoni, I.; Stenson, K.; Butler, J. N.; Cheung, H. W. K.; Chiodini, G.; Gaines, I.; Garbincius, P. H.; Garren, L. A.; Gottschalk, E.; Kasper, P. H.; Kreymer, A. E.; Kutschke, R.; Wang, M.; Benussi, L.; Bertani, M.; Bianco, S.; Fabbri, F. L.; Pacetti, S.; Zallo, A.; Reyes, M.; Cawlfield, C.; Kim, D. Y.; Rahimi, A.; Wiss, J.; Gardner, R.; Kryemadhi, A.; Chung, Y. S.; Kang, J. S.; Ko, B. R.; Kwak, J. W.; Lee, K. B.; Cho, K.; Park, H.; Alimonti, G.; Barberis, S.; Boschini, M.; Cerutti, A.; D'Angelo, P.; Dicorato, M.; Dini, P.; Edera, L.; Erba, S.; Inzani, P.; Leveraro, F.; Malvezzi, S.; Menasce, D.; Mezzadri, M.; Moroni, L.; Pedrini, D.; Pontoglio, C.; Prelz, F.; Rovere, M.; Sala, S.; Davenport, T. F.; Arena, V.; Boca, G.; Bonomi, G.; Gianini, G.; Liguori, G.; Lopes Pegna, D.; Merlo, M. M.; Pantea, D.; Ratti, S. P.; Riccardi, C.; Vitulo, P.; Gö, C.; Otalora, J.; Hernandez, H.; Lopez, A. M.; Mendez, H.; Paris, A.; Quinones, J.; Ramirez, J. E.; Zhang, Y.; Wilson, J. R.; Handler, T.; Mitchell, R.; Engh, D.; Hosack, M.; Johns, W. E.; Luiggi, E.; Moore, J. E.; Nehring, M.; Sheldon, P. D.; Vaandering, E. W.; Webster, M.; Sheaff, M.

2006-06-01

Using data collected by the FOCUS experiment at Fermilab, we present a new measurement of the charm semileptonic branching ratio BR(D→ρμν)BR(D→Kμν). From a sample of 320±44 and 11372±161D→ρμν and D→Kπμν events respectively, we find BR(D→ρμν)BR(D→Kμν)=0.041±0.006 (stat)±0.004 (syst).

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)

1,5-Diamino-2,6-dibromo-9,10-anthraquinone

Directory of Open Access Journals (Sweden)

Wilhelm Seichter

2012-03-01

Full Text Available In the title compound, C14H8Br2N2O2, the molecular structure features intramolecular N—H...O [2.639 (2 Å and 130°] and N—H...Br [3.053 (2 Å and 114°] hydrogen bonding. Due to inversion symmetry, the asymmetric part of the unit cell consits of one half-molecule. In the crystal, inversion dimers linked by pairs of N—H...O [2.955 (2 Å and 135°] hydrogen bonds occur. The structure also features C=O...π [3.228 (2 Å] and Br...Br [3.569 (1 Å] contacts.

Exploring Polaronic, Excitonic Structures and Luminescence in Cs4PbBr6/CsPbBr3.

Science.gov (United States)

Kang, Byungkyun; Biswas, Koushik

2018-02-15

Among the important family of halide perovskites, one particular case of all-inorganic, 0-D Cs 4 PbBr 6 and 3-D CsPbBr 3 -based nanostructures and thin films is witnessing intense activity due to ultrafast luminescence with high quantum yield. To understand their emissive behavior, we use hybrid density functional calculations to first compare the ground-state electronic structure of the two prospective compounds. The dispersive band edges of CsPbBr 3 do not support self-trapped carriers, which agrees with reports of weak exciton binding energy and high photocurrent. The larger gap 0-D material Cs 4 PbBr 6 , however, reveals polaronic and excitonic features. We show that those lattice-coupled carriers are likely responsible for observed ultraviolet emission around ∼375 nm, reported in bulk Cs 4 PbBr 6 and Cs 4 PbBr 6 /CsPbBr 3 composites. Ionization potential calculations and estimates of type-I band alignment support the notion of quantum confinement leading to fast, green emission from CsPbBr 3 nanostructures embedded in Cs 4 PbBr 6 .

Crystal structure of 4,4′-(ethane-1,2-diylbis(2,6-dibromoaniline

Directory of Open Access Journals (Sweden)

Ines Hauptvogel

2015-01-01

Full Text Available In the title compound, C14H12Br4N2, the molecule lies across an inversion center and hence the benzene rings are strictly coplanar. In the crystal, molecules are linked by N—H...N and weak N—H...Br hydrogen bonds, forming a two-dimensional network parallel to (101. In addition, type II Br...Br interactions [3.625 (4 Å] complete a three-dimensional supramolecular network.

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.

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

Yrityksen brändin uudistaminen

OpenAIRE

Saarimaa, Petri

2015-01-01

Brändin rakentaminen on tänä päivänä tärkeä osa yrityksen näkyvyyden ja kilpailukyvyn edistämisessä. Huolellisesti rakennetulla brändillä ja hyvällä markkinoinnilla yritys voi erottua kilpailijoistaan positiivisesti. Tie menestyvään brändiin on kuitenkin pitkä prosessi. Toimeksiantajana opinnäytetyössä toimi rakennusyritys Rakennus Vuoriot Oy. Opinnäytetyön tavoitteena oli toteuttaa yritykselle brändin uudistaminen luomalla kokonaan uusi perusta ja rakennusosat olemassa olevalle brändille...

cis-Bromido(methylaminebis(propane-1,3-diaminecobalt(III dibromide

Directory of Open Access Journals (Sweden)

P. S. Kannan

2013-07-01

Full Text Available In the title compound, [CoBr(CH5N(C3H10N22]Br2, the cobaltIII ion has a distorted octahedral coordination environment and is surrounded by four N atoms in the equatorial plane, with an additional N atom and the Br atom occupying the axial positions. In the crystal, the complex cation and the two counter anions are linked via N—H...Br and C—H...Br hydrogen bonds, forming a three-dimensional network.

The triel bond: a potential force for tuning anion-π interactions

Science.gov (United States)

Esrafili, Mehdi D.; Mousavian, Parisasadat

2018-02-01

Using ab-initio calculations, the mutual influence between anion-π and B···N or B···C triel bond interactions is investigated in some model complexes. The properties of these complexes are studied by molecular electrostatic potential, noncovalent interaction index, quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. According to the results, the formation of B···N or B···C triel bond interactions in the multi-component systems makes a significant shortening of anion-π distance. Such remarkable variation in the anion-π distances has not been reported previously. The strengthening of the anion-π bonding in the multi-component systems depend significantly on the nature of the anion, and it becomes larger in the order Br- > Cl- > F-. The parameters derived from the QTAIM and NBO methodologies are used to study the mechanism of the cooperativity between the anion-π and triel bond interactions in the multi-component complexes.

BR-319: Brazil's Manaus-Porto Velho highway and the potential impact of linking the arc of deforestation to central amazonia.

Science.gov (United States)

Fearnside, Philip M; de Alencastro Graça, Paulo Maurício Lima

2006-11-01

Brazil's BR-319 Highway linked Manaus, in the state of Amazonas, to Porto Velho, Rondônia, until it became impassable in 1988. Now it is proposed for reconstruction and paving, which would facilitate migration from the "Arc of Deforestation" in the southern part of the Amazon region to new frontiers farther north. The purpose of the highway, which is to facilitate transport to São Paulo of products from factories in the Manaus Free Trade Zone, would be better served by sending the containers by ship to the port of Santos. The lack of a land connection to Manaus currently represents a significant barrier to migration to central and northern Amazonia. Discourse regarding the highway systematically overestimates the highway's benefits and underestimates its impacts. A variety of changes would be needed prior to paving the highway if these potential impacts are to be attenuated. These include zoning, reserve creation, and increased governance in various forms, including deforestation licensing and control programs. More fundamental changes are also needed, especially the abandonment of the long-standing tradition in Brazil of granting squatters' rights to those who invade public land. Organizing Amazonian occupation in such a way that road construction and improvement cease to lead to explosive and uncontrolled deforestation should be a prerequisite for approval of the BR-319 and other road projects for which major impacts are expected. These projects could provide the impetus that is needed to achieve the transition away from appropriation of public land by both small squatters and by grileiros (large-scale illegal claimants). A delay in reconstructing the highway is advisable until appropriate changes can be effected.

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

Chanel-brändin nuorentaminen Suomessa

OpenAIRE

Auvinen, Elina

2017-01-01

Tämän opinnäytetyön tavoitteena oli kartoittaa Chanel-kosmetiikkabrändin imagoa ja asiakaskuntaa Suomessa sekä luoda saatujen tulosten pohjalta kehitysehdotuksia Chanel-brändin markkinointiin Suomessa brändin nuorentamisen näkökulmasta. Työn toimeksiantaja oli Chanel-brändin jakelija Oy Transmeri Ab. Teoriataustassa käsiteltiin laajasti erilaisia brändin nuorentamiseen liittyviä aihepiirejä; bränditeoriaa, brändien uudistamista, luksusbrändien erityispiirteitä sekä niiden asiakkaita, digitaal...

Nuclear Magnetic Resonance Reveals Disordered Level-Crossing Physics in the Bose-Glass Regime of the Br-Doped Ni(Cl_{1-x}Br_{x})_{2}-4SC(NH_{2})_{2} Compound at a High Magnetic Field.

Science.gov (United States)

Orlova, Anna; Blinder, Rémi; Kermarrec, Edwin; Dupont, Maxime; Laflorencie, Nicolas; Capponi, Sylvain; Mayaffre, Hadrien; Berthier, Claude; Paduan-Filho, Armando; Horvatić, Mladen

2017-02-10

By measuring the nuclear magnetic resonance (NMR) T_{1}^{-1} relaxation rate in the Br (bond) doped DTN compound, Ni(Cl_{1-x}Br_{x})_{2}-4SC(NH_{2})_{2}(DTNX), we show that the low-energy spin dynamics of its high magnetic field "Bose-glass" regime is dominated by a strong peak of spin fluctuations found at the nearly doping-independent position H^{*}≅13.6  T. From its temperature and field dependence, we conclude that this corresponds to a level crossing of the energy levels related to the doping-induced impurity states. Observation of the local NMR signal from the spin adjacent to the doped Br allowed us to fully characterize this impurity state. We have thus quantified a microscopic theoretical model that paves the way to better understanding of the Bose-glass physics in DTNX, as revealed in the related theoretical study [M. Dupont, S. Capponi, and N. Laflorencie, Phys. Rev. Lett. 118, 067204 (2017).PRLTAO0031-900710.1103/PhysRevLett.118.067204].

5-Bromo-3-(4-chlorophenylsulfinyl-2-methyl-1-benzofuran

Directory of Open Access Journals (Sweden)

Hong Dae Choi

2010-11-01

Full Text Available In the title compound, C15H10BrClO2S, the 4-chlorophenyl ring is oriented approximately perpendicular to the mean plane of the benzofuran ring [dihedral angle = 89.55 (9°]. In the crystal, molecules are linked through weak intermolecular C—H...O hydrogen bonds and and a Br...Br contact [3.783 (3 Å].

Effect of antioxidant agents on bond strength of composite to bleached enamel with 38% hydrogen peroxide

Directory of Open Access Journals (Sweden)

Juliane Marcela Guimaraes da Silva

2011-01-01

Full Text Available This study evaluated the effect of antioxidant agents on microtensile bond strengths (mTBS of composite to bleached enamel. Fifteen freshly extracted human third molars were selected and randomly assigned to 6 groups (n = 5: (NB enamel not bleached, (B bleached enamel, (BR7 bleached enamel and restored 7 days later, (BSA bleached enamel+sodium ascorbate, (BMC bleached enamel+malvidin chloride, (BPC bleached enamel+pelargonidin chloride. The groups were bleached with 38% hydrogen peroxide (HP - Opalescence Xtra Boost and restored with Single Bond+Filtek Z350. The specimens were thermocycled and submitted to a microtensile load at 1 mm/min crosshead speed. The data were evaluated by ANOVA and Tukey test at 5% of significance. The mean and standard-deviation for all groups were: NB: 30.95(±11.97a; BSA: 30.34(±8.73a, BPC: 22.81(6.00b, BR7: 21.41(±6.12b, B: 14.10(±4.45c, BMC: 13.25(±6.02c. Sodium ascorbate reversed the bond strengths to enamel immediately after bleaching.

Product state resolved excitation spectroscopy of He-, Ne-, and Ar-Br2 linear isomers: experiment and theory.

Science.gov (United States)

Pio, Jordan M; van der Veer, Wytze E; Bieler, Craig R; Janda, Kenneth C

2008-04-07

Valence excitation spectra for the linear isomers of He-, Ne-, and Ar-Br2 are reported and compared to a two-dimensional simulation using the currently available potential energy surfaces. Excitation spectra from the ground electronic state to the region of the inner turning point of the Rg-Br2 (B,nu') stretching coordinate are recorded while probing the asymptotic Br2 (B,nu') state. Each spectrum is a broad continuum extending over hundreds of wavenumbers, becoming broader and more blueshifted as the rare gas atom is changed from He to Ne to Ar. In the case of Ne-Br2, the threshold for producing the asymptotic product state reveals the X-state linear isomer bond energy to be 71+/-3 cm(-1). The qualitative agreement between experiment and theory shows that the spectra can be correctly regarded as revealing the one-atom solvent shifts and also provides new insight into the one-atom cage effect on the halogen vibrational relaxation. The measured spectra provide data to test future ab initio potential energy surfaces in the interaction of rare gas atoms with the halogen valence excited state.

Photoresponse of CsPbBr3 and Cs4PbBr6 Perovskite Single Crystals.

Science.gov (United States)

Cha, Ji-Hyun; Han, Jae Hoon; Yin, Wenping; Park, Cheolwoo; Park, Yongmin; Ahn, Tae Kyu; Cho, Jeong Ho; Jung, Duk-Young

2017-02-02

High-quality and millimeter-sized perovskite single crystals of CsPbBr 3 and Cs 4 PbBr 6 were prepared in organic solvents and studied for correlation between photocurrent generation and photoluminescence (PL) emission. The CsPbBr 3 crystals, which have a 3D perovskite structure, showed a highly sensitive photoresponse and poor PL signal. In contrast, Cs 4 PbBr 6 crystals, which have a 0D perovskite structure, exhibited more than 1 order of magnitude higher PL intensity than CsPbBr 3 , which generated an ultralow photoresponse under illumination. Their contrasting optoelectrical characteristics were attributed to different exciton binding energies, induced by coordination geometry of the [PbBr 6 ] 4- octahedron sublattices. This work correlated the local structures of lead in the primitive perovskite and its derivatives to PL spectra as well as photoconductivity.

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...

Hg0 and HgCl2 Reference Gas Standards: NIST Traceability and Comparability (And EPA ALT Methods for Hg and HCl )

Science.gov (United States)

EPA and NIST have collaborated to establish the necessary procedures for establishing the required NIST traceability of commercially-provided Hg0 and HgCl2 reference generators. This presentation will discuss the approach of a joint EPA/NIST study to accurately quantify the tru...

In situ Spectroscopy of Solid-State Chemical Reaction in PbBr2-Deposited CsBr Crystals

Science.gov (United States)

Kondo, Shin-ichi; Matsunaga, Toshihiro; Saito, Tadaaki; Asada, Hiroshi

2003-09-01

It is possible to measure the fundamental optical absorption spectra of CsPbBr3 and Cs4PbBr6, whose stability is predicted by the study of phase diagram in the binary system CsBr-PbBr2, by means of in situ optical absorption and reflection spectroscopy of thermally induced solid-state chemical reaction in PbBr2-deposited CsBr crystals. On heavy annealing of the crystals, the Pb2+ ions are uniformly dispersed in the crystal matrix. The present experiment provides a novel method for measuring intrinsic optical absorption of ternary metal halides and also for in situ monitoring of doping metal halide crystal with impurities (metal ions or halogen ions).

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

Revisiting the Brønsted acid catalysed hydrolysis kinetics of polymeric carbohydrates in ionic liquids by in situ ATR-FTIR spectroscopy

DEFF Research Database (Denmark)

Kunov-Kruse, Andreas Jonas; Riisager, Anders; Shunmugavel, Saravanamurugan

2013-01-01

A new versatile method to measure rates and determine activation energies for the Brønsted acid catalysed hydrolysis of cellulose and cellobiose (and other polymeric carbohydrates) in ionic liquids is demonstrated by following the C–O stretching band of the glycoside bond with in situ ATR...

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.

Tunable CsPbBr3/Cs4PbBr6 phase transformation and their optical spectroscopic properties.

Science.gov (United States)

Chen, Xiao; Chen, Daqin; Li, Junni; Fang, Gaoliang; Sheng, Hongchao; Zhong, Jiasong

2018-04-24

As a novel type of promising materials, metal halide perovskites are a rising star in the field of optoelectronics. On this basis, a new frontier of zero-dimensional perovskite-related Cs4PbBr6 with bright green emission and high stability has attracted an enormous amount of attention, even though its photoluminescence still requires to clarification. Herein, the controllable phase transformation between three-dimensional CsPbBr3 and zero-dimensional Cs4PbBr6 is easily achieved in a facile ligand-assisted supersaturated recrystallization synthesis procedure via tuning the amount of surfactants, and their unique optical properties are investigated and compared in detail. Both Cs4PbBr6 and CsPbBr3 produce remarkably intense green luminescence with quantum yields up to 45% and 80%, respectively; however, significantly different emitting behaviors are observed. The fluorescence lifetime of Cs4PbBr6 is much longer than that of CsPbBr3, and photo-blinking is easily detected in the Cs4PbBr6 product, proving that the zero-dimensional Cs4PbBr6 is indeed a highly luminescent perovskite-related material. Additionally, for the first time, tunable emissions over the visible-light spectral region are demonstrated to be achievable via halogen composition modulations in the Cs4PbX6 (X = Cl, Br, I) samples. Our study brings a simple method for the phase control of CsPbBr3/Cs4PbBr6 and demonstrates the intrinsic luminescence nature of the zero-dimensional perovskite-related Cs4PbX6 products.

Estimating BrAC from transdermal alcohol concentration data using the BrAC estimator software program.

Science.gov (United States)

Luczak, Susan E; Rosen, I Gary

2014-08-01

Transdermal alcohol sensor (TAS) devices have the potential to allow researchers and clinicians to unobtrusively collect naturalistic drinking data for weeks at a time, but the transdermal alcohol concentration (TAC) data these devices produce do not consistently correspond with breath alcohol concentration (BrAC) data. We present and test the BrAC Estimator software, a program designed to produce individualized estimates of BrAC from TAC data by fitting mathematical models to a specific person wearing a specific TAS device. Two TAS devices were worn simultaneously by 1 participant for 18 days. The trial began with a laboratory alcohol session to calibrate the model and was followed by a field trial with 10 drinking episodes. Model parameter estimates and fit indices were compared across drinking episodes to examine the calibration phase of the software. Software-generated estimates of peak BrAC, time of peak BrAC, and area under the BrAC curve were compared with breath analyzer data to examine the estimation phase of the software. In this single-subject design with breath analyzer peak BrAC scores ranging from 0.013 to 0.057, the software created consistent models for the 2 TAS devices, despite differences in raw TAC data, and was able to compensate for the attenuation of peak BrAC and latency of the time of peak BrAC that are typically observed in TAC data. This software program represents an important initial step for making it possible for non mathematician researchers and clinicians to obtain estimates of BrAC from TAC data in naturalistic drinking environments. Future research with more participants and greater variation in alcohol consumption levels and patterns, as well as examination of gain scheduling calibration procedures and nonlinear models of diffusion, will help to determine how precise these software models can become. Copyright © 2014 by the Research Society on Alcoholism.

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.

[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.

catena-Poly[[bromidocopper(I)]-?-?2,?1-3-(2-allyl-2H-tetra?zol-5-yl)pyridine

OpenAIRE

Wang, Wei

2008-01-01

The title compound, [CuBr(C9H9N5)] n , has been prepared by the solvothermal treatment of CuBr with 3-(2-allyl-2H-tetra?zol-5-yl)pyridine. It is a new homometallic CuI olefin coord?ination polymer in which the CuI atoms are linked by the 3-(2-allyl-2H-tetra?zol-5-yl)pyridine ligands and bonded to one terminal Br atom each. The organic ligand acts as a bidentate ligand connecting two neighboring Cu centers through the N atom of the pyridine ring and the double bond of the allyl group. A three-...

Photodissociation of C{sub 3}H{sub 5}Br and C{sub 4}H{sub 7}Br at 234 nm

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyun Kook; Paul, Dababrata; Hong, Ki Ryong; Cho, Ha Na; Kim, Tae Kyu [Pusan National University, Busan (Korea, Republic of); Lee, Kyoung Seok [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

2012-01-15

The photodissociation dynamics of cyclopropyl bromide (C-3H{sub 5}Br) and cyclobutyl bromide (C{sub 4}H{sub 7}Br) at 234 nm was investigated. A two-dimensional photofragment ion-imaging technique coupled with a [2+1] resonance enhanced multiphoton ionization scheme was utilized to obtain speed and angular distributions of the nascent Br({sup 2}P{sub 3/2}) and Br*({sup 2}P{sub 1/2}) atoms. The recoil anisotropies for the Br and Br* channels were measured to be βBr = 0.92 ± 0.03 and βBr* = 1.52 ± 0.04 for C{sub 3}H{sub 5}Br and βBr = 1.10 ± 0.03 and βBr* = 1.49 ± 0.05 for C{sub 4}H{sub 7}Br. The relative quantum yield for Br was found to be ΦBr = 0.13 ± 0.03 and for C{sub 3}H{sub 5}Br and C{sub 4}H{sub 7}Br, respectively. The soft radical limit of the impulsive model adequately modeled the related energy partitioning. The nonadiabatic transition probability from the 3A' and 4A' potential energy surfaces was estimated and discussed.

XeBr exciplex laser

International Nuclear Information System (INIS)

Searles, S.K.

1976-01-01

Laser emission from the recently discovered XeBr exciplex laser was investigated as a function of the partial pressures of Xe and Br 2 . An optical loss process appears to limit high-pressure operation

Elimination of nonspecific radioactivity from [{sup 76}Br]bromide in PET study with [{sup 76}Br]bromodeoxyuridine

Energy Technology Data Exchange (ETDEWEB)

Li Lu; Bergstroem, Mats E-mail: Mats.Bergstroem@pet.uu.se; Fasth, Karl-Johan; Wu Feng; Eriksson, Barbro; Laangstroem, Bengt

1999-10-01

[{sup 76}Br]Bromodeoxyuridine ([{sup 76}Br]BrdU) might allow a determination of proliferation in vivo using positron emission tomography (PET), but only with consideration of organ nonspecific radioactivity constituted by [{sup 76}Br]bromide. A first study assessed the potential of diuretics to eliminate [{sup 76}Br]bromide. [{sup 76}Br]Bromide was injected in the vein of rats and different diuretic combinations were given. Urine was collected and radioactivity measured. Torasemide plus sodium chloride gave better {sup 76}Br elimination than the other diuretics. In a second experiment, rats were given [{sup 76}Br]BrdU. After the radioactivity injection, the rats of the treatment group were given torasemide plus NaCl. At 44 h after the radioactivity injection, the radioactivity concentration and the fraction incorporated into DNA were measured in different organs. Using diuretics, the elimination of [{sup 76}Br]bromide was increased. The radioactivity decreased 30-50% in most of the organs but the highest radioactivity uptake was found in the organs with more active DNA synthesis. This method may facilitate the use of [{sup 76}Br]BrdU as a tracer for DNA synthesis using PET.

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.)

Investigations on the system Te/O/Br

International Nuclear Information System (INIS)

Oppermann, H.; Kunze, G.; Wolf, E.; Titov, V.A.; Kokovin, G.A.

1978-01-01

The melting point diagram of the system TeBr 4 -TeO 2 was obtained by total pressure measurements and DTA measurements. A congruent melting composition Te 6 O 11 Br 2 exists, the melting point is 570 0 C. The enthalpy of formation and the standard entropy of the species TeOBr 2 ,g was derived from measurements of the total pressure over Te 6 O 11 Br 2 /TeBr 4 and from the transport behaviour of the TeO 2 with Br 2 . From the decomposition-pressure measurements over Te 6 O 11 Br 2 /TeO 2 follow the partial pressures. The enthalpy of formation ΔH 0 (Te 6 O 11 Br 2 ,f,298) -453.5 kcal/Mol was obtained from the enthalpy of solution. The transport-behaviour of TeO 2 with HBr, TeBr 4 and Br 2 and that of Te 6 O 11 Br 2 is clear with the thermodynamic data of TeOBr 2 . (author)

Theoretical investigation of potential energy surface and bound states for the van der Waals complex Ar–BrCl dimer

Energy Technology Data Exchange (ETDEWEB)

Zheng, Rui [School of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou (China); Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan (China); Li, Song, E-mail: lsong@yangtzeu.edu.cn [School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou (China); Chen, Shan-Jun; Chen, Yan [School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou (China); Zheng, Li-Min [Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan (China)

2015-09-08

Highlights: • A two-dimensional potential for Ar–BrCl is constructed at the CCSD(T) level. • The PES is characterized by three minima and two saddle points between them. • Bound state calculations were carried out for the complex. - Abstract: The intermolecular potential energy surface (PES) of the ground electronic state for the Ar–BrCl dimer is constructed at the CCSD(T) level with the aug-cc-pVQZ basis set and mid-bond functions. The PES is characterized by three minima and two saddle points. The global minimum corresponding to a collinear Ar–BrCl configuration, which has been observed experimentally, is located at R = 4.10 Å and θ = 2.5° with a well depth of −285.207 cm{sup −1}. A nearly T-shaped structure and an anti-linear Ar–ClBr geometry is also predicted. The bound state calculations are preformed to study intermolecular vibrational modes, rotational levels and average structures for the complex. Our transition frequencies, spectroscopic constants and average structures for all isotopomers of the collinear isomer agree well with experimental data. We have also provided pure rotational transitional frequencies for both nearly T-shaped and anti-linear isomers. These results are significant for further experimental investigations of the Ar–BrCl dimer.

Polymeric anionic networks using dibromine as a crosslinker; the preparation and crystal structure of [(C4H9)4N]2[Pt2Br10].(Br2)7 and [(C4H9)4N]2[PtBr4Cl2].(Br2)6.

Science.gov (United States)

Berkei, Michael; Bickley, Jamie F; Heaton, Brian T; Steiner, Alexander

2002-09-21

The reaction of M[PtX3(CO)] (M+ = [(C4H9)4N]+, X = Br, Cl) with an excess of Br2 gives the new platinum(IV) salts, [(C4H9)4N]2[Pt2Br10].(Br2)7, 1, and [(C4H9)4N]2[PtBr4Cl2].(Br2)6, 2, which, in the solid state, contain strong Br Br interactions resulting in the formation of polymeric networks; they could provide useful solid storage reservoirs for elemental bromine.

Addition reaction of adamantylideneadamantane with Br2 and 2Br2: a computational study.

Science.gov (United States)

Islam, Shahidul M; Poirier, Raymond A

2008-01-10

Ab initio calculations were carried out for the reaction of adamantylideneadamantane (Ad=Ad) with Br2 and 2Br2. Geometries of the reactants, transition states, intermediates, and products were optimized at HF and B3LYP levels of theory using the 6-31G(d) basis set. Energies were also obtained using single point calculations at the MP2/6-31G(d)//HF/6-31G(d), MP2/6-31G(d)//B3LYP/6-31G(d), and B3LYP/6-31+G(d)//B3LYP/6-31G(d) levels of theory. Intrinsic reaction coordinate (IRC) calculations were performed to characterize the transition states on the potential energy surface. Only one pathway was found for the reaction of Ad=Ad with one Br2 producing a bromonium/bromide ion pair. Three mechanisms for the reaction of Ad=Ad with 2Br2 were found, leading to three different structural forms of the bromonium/Br3- ion pair. Activation energies, free energies, and enthalpies of activation along with the relative stability of products for each reaction pathway were calculated. The reaction of Ad=Ad with 2Br2 was strongly favored over the reaction with only one Br2. According to B3LYP/6-31G(d) and single point calculations at MP2, the most stable bromonium/Br3- ion pair would form spontaneously. The most stable of the three bromonium/Br3- ion pairs has a structure very similar to the observed X-ray structure. Free energies of activation and relative stabilities of reactants and products in CCl4 and CH2ClCH2Cl were also calculated with PCM using the united atom (UA0) cavity model and, in general, results similar to the gas phase were obtained. An optimized structure for the trans-1,2-dibromo product was also found at all levels of theory both in gas phase and in solution, but no transition state leading to the trans-1,2-dibromo product was obtained.

3-Benzyl-6-bromo-2-(2-furyl-3H-imidazo[4,5-b]pyridine

Directory of Open Access Journals (Sweden)

Younès Ouzidan

2010-07-01

Full Text Available In the title molecule, C17H12BrN3O, the imidazopyridine ring system is almost coplanar with the furan ring [dihedral angle = 2.0 (3°]. The benzyl phenyl ring is oriented at dihedral angles of 85.2 (2 and 85.5 (1°, respectively, with respect to the furan ring and the imidazopyridine ring system. In the crystal, molecules are linked into chains propagating along the b axis by C—H...N hydrogen bonds. Adjacent chains are linked via short Br...Br contacts [3.493 (1 Å].

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.

Application of bonded NdFeB magnet for C-Band circulator component

Science.gov (United States)

Kristiantoro, T.; Idayanti, N.; Sudrajat, N.; Septiani, A.; Dedi

2016-11-01

In this paper bonded NdFeB permanent magnets of the crashed-ribbon type were made as an alternative for circulator magnet to improve their magnetic performance. The fabrication process is also easier than the sintered NdFeB because there had no shrinkage of product (such as sintered barium ferrite magnet), with the others advantages as follows; large freeness of product shapes, high precision of dimension and good corrosion resistance. The dimension of the samples was measured to calculate its bulk densities and the magnetic properties were characterized by Permagraph to obtain values such as; Remanence induction (Br) in kG, Coercivity value (Hcj) in kOe, the Maximum energy product (BH max) in MGOe. Whereas the surface magnetic field strength (B) was observed by the Gauss-meter. The bonded NdFeB permanent magnets revealed 6.39 kG of Br, 6.974 kOe of Hcj and 7.13 MGOe of BHmax. The circulator performance was measured using Vector Network Analyzer (VNA). The optimum values of the circulator measurement at a frequency of 5 GHz show a VSWR value of 1.062 and insertion loss of -0.463 dB. The bonded magnet could be used as component of permanent magnets on the circulator that working on C-Band at a frequency range of 4 GHz - 8 GHz.

Large shift and small broadening of Br2 valence band upon dimer formation with H2O: an ab initio study.

Science.gov (United States)

Franklin-Mergarejo, Ricardo; Rubayo-Soneira, Jesus; Halberstadt, Nadine; Ayed, Tahra; Bernal-Uruchurtu, Margarita I; Hernández-Lamoneda, Ramón; Janda, Kenneth C

2011-06-16

Valence electronic excitation spectra are calculated for the H(2)O···Br(2) complex using highly correlated ab initio potentials for both the ground and the valence electronic excited states and a 2-D approximation for vibrational motion. Due to the strong interaction between the O-Br and the Br-Br stretching motions, inclusion of these vibrations is the minimum necessary for the spectrum calculation. A basis set calculation is performed to determine the vibrational wave functions for the ground electronic state and a wave packet simulation is conducted for the nuclear dynamics on the excited state surfaces. The effects of both the spin-orbit interaction and temperature on the spectra are explored. The interaction of Br(2) with a single water molecule induces nearly as large a shift in the spectrum as is observed for an aqueous solution. In contrast, complex formation has a remarkably small effect on the T = 0 K width of the valence bands due to the fast dissociation of the dihalogen bond upon excitation. We therefore conclude that the widths of the spectra in aqueous solution are mostly due to inhomogeneous broadening. © 2011 American Chemical Society

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.

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.

2-Amino-5-bromopyridinium hydrogen succinate

Directory of Open Access Journals (Sweden)

Hoong-Kun Fun

2010-03-01

Full Text Available In the title compound, C5H6BrN2+·C4H5O4−, the pyridine N atom of the 2-amino-5-bromopyridine molecule is protonated. The protonated N atom and the amino group are linked via N—H...O hydrogen bonds to the carboxylate O atoms of the singly deprotonated succinate anion. The hydrogen succinate anions are linked via O—H...O hydrogen bonds. A weak intermolecular C—H...O hydrogen bond is also observed.

Bond markets in Africa

Directory of Open Access Journals (Sweden)

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.

Enhanced surface modification engineering (H, F, Cl, Br, and NO{sub 2}) of CdS nanowires with and without surface dangling bonds

Energy Technology Data Exchange (ETDEWEB)

Zeng, Yijie; Xing, Huaizhong, E-mail: xinghz@dhu.edu.cn; Lu, Aijiang; Wang, Chunrui; Xu, Xiaofeng [Department of Applied Physics and State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Ren Min Road 2999, Songjiang District, Shanghai 201620 (China); Huang, Yan; Chen, Xiaoshuang, E-mail: jqwang@ee.ecnu.edu.cn, E-mail: xschen@mail.sitp.ac.cn [National Lab. of Infrared Physics, Shanghai Institute for Technical Physics, Chinese Academy of Science, 500 Yu Tian Road, Shanghai 200083 (China); Wang, Jiqing, E-mail: jqwang@ee.ecnu.edu.cn, E-mail: xschen@mail.sitp.ac.cn [Key Laboratory of Polarized Materials and Devices, East China Normal University, Shanghai 200062 (China)

2015-08-07

Semiconductor nanowires (NWs) can be applied in gas sensing and cell detection, but the sensing mechanism is not clearly understood. In this study, surface modification effect on the electronic properties of CdS NWs for different diameters with several species (H, F, Cl, Br, and NO{sub 2}) is investigated by first principles calculations. The surface dangling bonds and halogen elements are chosen to represent the environment of the surface. Halogen passivation drastically changes the band gaps due to the strong electronegativity and the energy level of halogen atoms. Density of states analysis indicates that valence band maximum (VBM) of halogen-passivated NWs is formed by the p states of halogen atoms, while VBM of H-passivated NWs is originated from Cd 4d and S 3p orbitals. To illustrate that surface modification can be applied in gas sensing, NO{sub 2}-absorbed NWs with different coverage are calculated. Low coverage of NO{sub 2} introduces a deep p-type dopant-like level, while high coverage introduces a shallow n-type dopant-like level into the band structure. The transformation is due to that at low coverage the adsorption is chemical while at high coverage is physical. These findings might promote the understanding of surface modification effect and the sensing mechanism of NWs as gas sensors.

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.

Postsynthesis Transformation of Insulating Cs4PbBr6 Nanocrystals into Bright Perovskite CsPbBr3 through Physical and Chemical Extraction of CsBr.

Science.gov (United States)

Palazon, Francisco; Urso, Carmine; De Trizio, Luca; Akkerman, Quinten; Marras, Sergio; Locardi, Federico; Nelli, Ilaria; Ferretti, Maurizio; Prato, Mirko; Manna, Liberato

2017-10-13

Perovskite-related Cs 4 PbBr 6 nanocrystals present a "zero-dimensional" crystalline structure where adjacent [PbBr 6 ] 4- octahedra do not share any corners. We show in this work that these nanocrystals can be converted into "three-dimensional" CsPbBr 3 perovskites by extraction of CsBr. This conversion drastically changes the optoelectronic properties of the nanocrystals that become highly photoluminescent. The extraction of CsBr can be achieved either by thermal annealing (physical approach) or by chemical reaction with Prussian Blue (chemical approach). The former approach can be simply carried out on a dried film without addition of any chemicals but does not yield a full transformation. Instead, reaction with Prussian Blue in solution achieves a full transformation into the perovskite phase. This transformation was also verified on the iodide counterpart (Cs 4 PbI 6 ).

Supramolecular structures in N-isonicotinoyl arylaldehydehydrazones: multiple hydrogen-bonding modes in series of geometric isomers.

Science.gov (United States)

Wardell, Solange M S V; de Souza, Marcus V N; Wardell, James L; Low, John N; Glidewell, Christopher

2007-12-01

Sixteen N-isonicotinoyl arylaldehydehydrazones, NC(5)H(4)CONHN=CHC(6)H(4)R, have been studied and the structures of 14 of them have been determined, including the unsubstituted parent compound with R = H, and the complete sets of 2-, 3- and 4-substituted geometric isomers for R = F, Br and OMe, and two of the three isomers for R = Cl and OEt. The 2-chloro and 3-chloro derivatives are isostructural with the corresponding bromo isomers, and all compounds contain trans amide groups apart from the isostructural pair where R = 2-Cl and 2-Br, which contain cis amide groups. The structures exhibit a wide range of direction-specific intermolecular interactions, including eight types of hydrogen bonds, N-H...N, N-H...O, O-H...O, O-H...N, C-H...N, C-H...O, C-H...pi(arene) and C-H...pi(pyridyl), as well as pi...pi stacking interactions. The structures exhibit a very broad range of combinations of these interactions: the resulting hydrogen-bonded supramolecular structures range from one-dimensional when R = 2-F, 2-OMe or 2-OEt, via two-dimensional when R = 4-F, 3-Cl, 3-Br, 4-OMe or 3-OEt, to three-dimensional when R = H, 3-F, 2-Cl, 2-Br, 4-Br or 3-OMe. Minor changes in either the identity of the substituent or its location can lead to substantial changes in the pattern of supramolecular aggregation, posing significant problems of predictability. The new structures are compared with the recently published structures of the isomeric series having R = NO(2), with several monosubstituted analogues containing 2-pyridyl or 3-pyridyl units rather than 4-pyridyl, and with a number of examples having two or three substituents in the aryl ring: some 30 structures in all are discussed.

An example of operation for a partly manned Antarctic geomagnetic observatory and the development of a radio link for data transmission

Directory of Open Access Journals (Sweden)

Joan L. Pijoan

2009-06-01

Full Text Available The experience acquired from more than ten years of operation of an Antarctic geomagnetic observatory is described<br />along with the development of data transmission facilities. The observatory was deployed at the Spanish Antarctic<br />Station in 1996. The main instrument was an Overhauser magnetometer deployed in dual axis Helmholtz coils, a<br />δD/δI configuration. The site is only manned during the summer, with the magnetometer left recording throughout<br />the rest of the year. During the 2007-2008 survey the observatory instrumentation has been upgraded with a DMI<br />suspended triaxial fluxgate magnetometer, new sampling hardware and data logging software. Both sampling and<br />timing are carried out under the control of a PIC based microcontroller and GPS receiver. Data presentation, transmission<br />and archiving are performed under the control of a low power embedded PC. For real time access to the data<br />two options have been provided and rigorously tested during the last 10 years: METEOSAT and GOES Data Collection<br />Systems, and recently, a high frequency (HF digital radio-link, using ionospheric propagation between<br />Antarctica and Spain, has been developed. This latest transmission system is being continuously upgraded, and it<br />would be possible to extend its application to other remote stations. Measurements have been made during the last<br />four years in order to determine the channel characteristics and its variability, mainly the multipath and Doppler<br />spread and the link availability for a given SNR in the receiver. These measurements are being used to design the<br />physical layer of a radiomodem intended to maximize the link capacity keeping the emitted power low.

Balloon-borne stratospheric BrO measurements: comparison with Envisat/SCIAMACHY BrO limb profiles

Directory of Open Access Journals (Sweden)

M. Dorf

2006-01-01

Full Text Available For the first time, results of four stratospheric BrO profiling instruments, are presented and compared with reference to the SLIMCAT 3-dimensional chemical transport model (3-D CTM. Model calculations are used to infer a BrO profile validation set, measured by 3 different balloon sensors, for the new Envisat/SCIAMACHY (ENVIronment SATellite/SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY satellite instrument. The balloon observations include (a balloon-borne in situ resonance fluorescence detection of BrO (Triple, (b balloon-borne solar occultation DOAS measurements (Differential Optical Absorption Spectroscopy of BrO in the UV, and (c BrO profiling from the solar occultation SAOZ (Systeme d'Analyse par Observation Zenithale balloon instrument. Since stratospheric BrO is subject to considerable diurnal variation and none of the measurements are performed close enough in time and space for a direct comparison, all balloon observations are considered with reference to outputs from the 3-D CTM. The referencing is performed by forward and backward air mass trajectory calculations to match the balloon with the satellite observations. The diurnal variation of BrO is considered by 1-D photochemical model calculation along the trajectories. The 1-D photochemical model is initialised with output data of the 3-D model with additional constraints on the vertical transport, the total amount and photochemistry of stratospheric bromine as given by the various balloon observations. Total [Bry]=(20.1±2.5 pptv obtained from DOAS BrO observations at mid-latitudes in 2003, serves as an upper limit of the comparison. Most of the balloon observations agree with the photochemical model predictions within their given error estimates. First retrieval exercises of BrO limb profiling from the SCIAMACHY satellite instrument on average agree to around 20% with the photochemically-corrected balloon observations of the remote sensing instruments (SAOZ

Energikravene i BR15

DEFF Research Database (Denmark)

Kragh, Jesper; Aggerholm, Søren

2015-01-01

Bygningsreglement 2015 – BR15 – gælder fra 1. januar 2016 med en overgangsfase frem til 1. juli 2016. Det bygger videre på BR10 og de tidligere udmeldte krav til nybyggeriet frem mod 2020. I denne kvikguide får du hurtigt overblik over, hvordan du sikrer, at de bygninger, du er med til at opføre...... eller renovere, lever op til BR15’s energikrav. Disse krav findes primært i reglementets kapitel 7 om energiforbrug og i kapitel 8 om installationer samt i kapitel 6 om indeklima....

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

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.

Crystal structure of bromidobis(naphthalen-1-ylantimony(III

Directory of Open Access Journals (Sweden)

Omar bin Shawkataly

2014-10-01

Full Text Available In the title compound, [SbBr(C10H72], the SbIII atom has a distorted trigonal–pyramidal coordination geometry and the planes of the two naphthalene ring systems make a dihedral angle of 80.26 (18°. An intramolecular C—H...Br hydrogen bond forms an S(5 ring motif. In the crystal, weak C—H...Br interactions link the molecules into helical chains along the b-axis direction.

rac-1-(2-Aminocarbonyl-2-bromoethylpyridinium bromide

Directory of Open Access Journals (Sweden)

Robert Köppen

2012-06-01

Full Text Available In the crystal structure of the title compound, C8H10BrN2O+·Br−, intermolecular N—H...Br hydrogen bonds link the molecules into infinite chains along [001]. The inclined angle between the pyridine ring plane and the plane defined by the acid amide group is 63.97 (4°.

Solvation dynamics through Raman spectroscopy: hydration of Br2 and Br3(-), and solvation of Br2 in liquid bromine.

Science.gov (United States)

Branigan, Edward T; Halberstadt, N; Apkarian, V A

2011-05-07

Raman spectroscopy of bromine in the liquid phase and in water illustrates uncommon principles and yields insights regarding hydration. In liquid Br(2), resonant excitation over the B((3)Π(0u)(+)) ← X((1)Σ(g)(+)) valence transition at 532 nm produces a weak resonant Raman (RR) progression accompanied by a five-fold stronger non-resonant (NR) scattering. The latter is assigned to pre-resonance with the C-state, which in turn must be strongly mixed with inter-molecular charge transfer states. Despite the electronic resonance, RR of Br(2) in water is quenched. At 532 nm, the homogeneously broadened fundamental is observed, as in the NR case at 785 nm. The implications of the quenching of RR scattering are analyzed in a simple, semi-quantitative model, to conclude that the inertial evolution of the Raman packet in aqueous Br(2) occurs along multiple equivalent water-Br(2) coordinates. In distinct contrast with hydrophilic hydration in small clusters and hydrophobic hydration in clathrates, it is concluded that the hydration shell of bromine in water consists of dynamically equivalent fluxional water molecules. At 405 nm, the RR progression of Br(3)(-) is observed, accompanied by difference transitions between the breathing of the hydration shell and the symmetric stretch of the ion. The RR scattering process in this case can be regarded as the coherent photo-induced electron transfer to the solvent and its radiative back-transfer.

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.

Measurement of the ratio of branching ratios BR(B+ → J/ψK+)/BR(B0 → J/φK0) and BR(B+ → J/ψK+)/BR(B+ → J/ψK*+)

International Nuclear Information System (INIS)

Atavales, J. B. G.

1995-01-01

A preliminary measurement of the ratio of branching ratios BR(B + → J/ψK + )/BR(B 0 → J/ψK 0 ) and BR(B + → J/ψK + )/BR(B + → J/ψK *+ ) is made by fully reconstructing each mode, where J/ψ → μ + μ - , K *+ → K 0 s π + and K 0 s → π + π - . The data were taken with the CDF detector during the 1993 run. The total integrated luminosity is ∼ 20pb -1 resulting in a sample of about 170 J/ψK ± , 50 J/ψK 0 S and 25 J/ψK *± candidate events. The results will be reported

Vibrational spectroscopic and theoretical study of 3,5-dimethyl-1-thiocarboxamide pyrazole (L) and the complexes Co2L2Cl4, Cu2L2Cl4 and Cu2L2Br2

International Nuclear Information System (INIS)

Nemcsok, Denes; Kovacs, Attila; Szecsenyi, Katalin Meszaros; Leovac, Vukadin M.

2006-01-01

In the present paper we report a joint experimental and theoretical study of 3,5-dimethyl-1-thiocarboxamide pyrazole (L) and its complexes Co 2 L 2 Cl 4 , Cu 2 L 2 Cl 4 and Cu 2 L 2 Br 2 . DFT computations were used to model the structural and bonding properties of the title compounds as well as to derive a reliable force field for the normal coordinate analysis of L. The computations indicated the importance of hydrogen bonding interactions in stabilising the global minimum structures on the potential energy surfaces. In contrast to the S-bridged binuclear Cu 2 L 2 Br 2 complex found in the crystal, our computations predicted the formation of (CuLBr) 2 dimers in the isolated state stabilized by very strong (53 kJ/mol) N-H...Br hydrogen bonding interactions. On the basis of FT-IR and FT-Raman experiments and the DFT-derived scaled quantum mechanical force field we carried out a complete normal coordinate analysis of L. The FT-IR spectra of the three complexes were interpreted using the present assignment of L, literature data and computed results

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

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.

Reactivity of BrCl, Br₂, BrOCl, Br₂O, and HOBr toward dimethenamid in solutions of bromide + aqueous free chlorine.

Science.gov (United States)

Sivey, John D; Arey, J Samuel; Tentscher, Peter R; Roberts, A Lynn

2013-02-05

HOBr, formed via oxidation of bromide by free available chlorine (FAC), is frequently assumed to be the sole species responsible for generating brominated disinfection byproducts (DBPs). Our studies reveal that BrCl, Br(2), BrOCl, and Br(2)O can also serve as brominating agents of the herbicide dimethenamid in solutions of bromide to which FAC was added. Conditions affecting bromine speciation (pH, total free bromine concentration ([HOBr](T)), [Cl(-)], and [FAC](o)) were systematically varied, and rates of dimethenamid bromination were measured. Reaction orders in [HOBr](T) ranged from 1.09 (±0.17) to 1.67 (±0.16), reaching a maximum near the pK(a) of HOBr. This complex dependence on [HOBr](T) implicates Br(2)O as an active brominating agent. That bromination rates increased with increasing [Cl(-)], [FAC](o) (at constant [HOBr](T)), and excess bromide (where [Br(-)](o)>[FAC](o)) implicate BrCl, BrOCl, and Br(2), respectively, as brominating agents. As equilibrium constants for the formation of Br(2)O and BrOCl (aq) have not been previously reported, we have calculated these values (and their gas-phase analogues) using benchmark-quality quantum chemical methods [CCSD(T) up to CCSDTQ calculations plus solvation effects]. The results allow us to compute bromine speciation and hence second-order rate constants. Intrinsic brominating reactivity increased in the order: HOBr ≪ Br(2)O Br(2) < BrCl. Our results indicate that species other than HOBr can influence bromination rates under conditions typical of drinking water and wastewater chlorination.

??????????? ????????? ???????????? ???????????? NH4X (?=??,?1) ??? ??????????? CdxHgi-xTe ??????? ???????? ???????????? ???????

OpenAIRE

??????, ?. ?.; ?????????, ?. ?.; ???????, ?. ?.; ?????????, ?. ?.; ?????????, ?. ?.

2004-01-01

?? ?????? ??????????? ?????????? ???????????? ?????? ??????? ???? ??????? CdxHgi_xTe-Hg-NH4Br ??? ??????? ?????? Hg ? ????????? ?????????? 560-860? ? ??????????? ?????? ?? = 103-=-105 ?? ????????? ????????, ??? ??????? ???????? ????? ? ??????????????? ??????, ????? ? ?????? - CdBr2, Hg, ??2. ??? ????????? ??????? ??????? ???????????? CdxHgi_xTe ??????? ? = 0.2; 0.3; 0.4 ?? ????????? ??? ??? ? ??? ?????????? ??????? ???????? ??????? (??? ?????? ?????? ????? ? ???????) ????????? ??????????? ???...

The BR eigenvalue algorithm

Energy Technology Data Exchange (ETDEWEB)

Geist, G.A. [Oak Ridge National Lab., TN (United States). Computer Science and Mathematics Div.; Howell, G.W. [Florida Inst. of Tech., Melbourne, FL (United States). Dept. of Applied Mathematics; Watkins, D.S. [Washington State Univ., Pullman, WA (United States). Dept. of Pure and Applied Mathematics

1997-11-01

The BR algorithm, a new method for calculating the eigenvalues of an upper Hessenberg matrix, is introduced. It is a bulge-chasing algorithm like the QR algorithm, but, unlike the QR algorithm, it is well adapted to computing the eigenvalues of the narrowband, nearly tridiagonal matrices generated by the look-ahead Lanczos process. This paper describes the BR algorithm and gives numerical evidence that it works well in conjunction with the Lanczos process. On the biggest problems run so far, the BR algorithm beats the QR algorithm by a factor of 30--60 in computing time and a factor of over 100 in matrix storage space.

Hydrogen bonding between hydrides of the upper-right part of the periodic table

Science.gov (United States)

Simončič, Matjaž; Urbic, Tomaz

2018-05-01

One of the most important electrostatic interactions between molecules is most definitely the hydrogen bond. Understanding the basis of this interaction may offer us the insight needed to understand its effect on the macroscopic scale. Hydrogen bonding is for example the reason for anomalous properties in compounds like water and naturally life as we know it. The strength of the bond depends on numerous factors, among them the electronegativity of participating atoms. In this work we calculated the strength of hydrogen bonds between hydrides of the upper-right part of the periodic table (C, N, O, F, P, S, Cl, As, Se, Br) using quantum-chemical methods. The aim was to determine what influences the strength of strong and weak hydrogen bonds in simple hydrides. Various relationships were checked. A relation between the strength of the bond and the electronegativity of the participating atoms was found. We also observed a correlation between the strength of hydrogen bonds and the inter-atomic distances, along with the dependence on the charge transfer on the atom of the donor. We also report characteristic geometries of different dimers.

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

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.

Coordination variation of hydrated Cu2+/Br1− ions traversing the interfacial water in mesopores

Directory of Open Access Journals (Sweden)

Q. Wang

2012-06-01

Full Text Available Resolution of the atomistic and electronic details about the coordination structure variation of hydrated ions in the interfacial water is still a tough challenge, which is, however, essentially important for the understanding of ion adsorption, permeation and other similar processes in aqueous solutions. Here we report the tracing of coordination structure variation for hydrated Cu2+/Br1- ions traversing the interfacial water in Vycor mesopores (ϕ = 7.6 nm by employing both X-ray absorption near edge structure and extended X-ray absorption fine structure spectroscopies. By controlled desorption/adsorption of water, the filling fraction of the mesopores, thus the water layer thickness, can be adjusted, which in turn effects the variation of coordination structure of the ions therein. It is found that both Cu2+ and Br1- ions prefer staying exclusively in the core water, and in this circumstance no ion pairs have been detected in the solution of concentrations up to 1.0 M. Following capillary decondensation occurring at a filling fraction of ∼35% which corresponds to a water layer of about three monolayers, Br1- ions begin immediately to reconstruct their first coordination shell, characterized by ionic dehydration, shrinkage of ion-water bond length, and formation of ion pairs. In contrast, Cu2+ ions can retain a bulk-like coordination structure till being driven to bond directly to the pore surface when the filling fraction is below 20%. At the final stage of dehydration via thermal vacuum treatment at 110°C, Cu2+ ions can be completely reduced to the Cu1+ state, and recover at room temperature only when the filling fraction is above 14%. These results may be inspirable for the investigation of similar problems concerning hydrated ions in water solution under different confining conditions.

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.

Importance of halogen···halogen contacts for the structural and magnetic properties of CuX2(pyrazine-N,N′-dioxide)(H2O)2 (X = Cl and Br).

Science.gov (United States)

Schlueter, John A; Park, Hyunsoo; Halder, Gregory J; Armand, William R; Dunmars, Cortney; Chapman, Karena W; Manson, Jamie L; Singleton, John; McDonald, Ross; Plonczak, Alex; Kang, Jinhee; Lee, Chaghoon; Whangbo, Myung-Hwan; Lancaster, Tom; Steele, Andrew J; Franke, Isabel; Wright, Jack D; Blundell, Stephen J; Pratt, Francis L; deGeorge, Joseph; Turnbull, Mark M; Landee, Christopher P

2012-02-20

The structural and magnetic properties of the newly crystallized CuX(2)(pyzO)(H(2)O)(2) (X = Cl, Br; pyzO = pyrazine-N,N'-dioxide) coordination polymers are reported. These isostructural compounds crystallize in the monoclinic space group C2/c with, at 150 K, a = 17.0515(7) Å, b = 5.5560(2) Å, c = 10.4254(5) Å, β = 115.400(2)°, and V = 892.21(7) Å(3) for X = Cl and a = 17.3457(8) Å, b = 5.6766(3) Å, c = 10.6979(5) Å, β = 115.593(2)°, and V = 950.01(8) Å(3) for X = Br. Their crystal structure is characterized by one-dimensional chains of Cu(2+) ions linked through bidentate pyzO ligands. These chains are joined together through OH···O hydrogen bonds between the water ligands and pyzO oxygen atoms and Cu-X···X-Cu contacts. Bulk magnetic susceptibility measurements at ambient pressure show a broad maximum at 7 (Cl) and 28 K (Br) that is indicative of short-range magnetic correlations. The dominant spin exchange is the Cu-X···X-Cu supersuperexchange because the magnetic orbital of the Cu(2+) ion is contained in the CuX(2)(H(2)O)(2) plane and the X···X contact distances are short. The magnetic data were fitted to a Heisenberg 1D uniform antiferromagnetic chain model with J(1D)/k(B) = -11.1(1) (Cl) and -45.9(1) K (Br). Magnetization saturates at fields of 16.1(3) (Cl) and 66.7(5) T (Br), from which J(1D) is determined to be -11.5(2) (Cl) and -46.4(5) K (Br). For the Br analog the pressure dependence of the magnetic susceptibility indicates a gradual increase in the magnitude of J(1D)/k(B) up to -51.2 K at 0.84 GPa, suggesting a shortening of the Br···Br contact distance under pressure. At higher pressure X-ray powder diffraction data indicates a structural phase transition at ∼3.5 GPa. Muon-spin relaxation measurements indicate that CuCl(2)(pyzO)(H(2)O)(2) is magnetically ordered with T(N) = 1.06(1) K, while the signature for long-range magnetic order in CuBr(2)(pyzO)(H(2)O)(2) was much less definitive down to 0.26 K. The results for the Cu

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

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

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

Bromidotetra?kis?(1H-2-ethyl-5-methyl?imidazole-?N 3)copper(II) bromide

OpenAIRE

Godlewska, Sylwia; Baranowska, Katarzyna; Socha, Joanna; Do??ga, Anna

2011-01-01

The CuII ion in the title compound, [CuBr(C6H10N2)4]Br, is coordinated in a square-based-pyramidal geometry by the N atoms of four imidazole ligands and a bromide anion in the apical site. Both the CuII and Br− atoms lie on a crystallographic fourfold axis. In the crystal, the [CuBr(C6H10N2)4]+ complex cations are linked to the uncoordinated Br− anions (site symmetry overline{4}) by N—H...Br hydrogen bonds, generating a three-dimensional network. The ethyl group ...

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.

Oxidation mechanisms of CF2Br2 and CH2Br2 induced by air nonthermal plasma.

Science.gov (United States)

Schiorlin, Milko; Marotta, Ester; Dal Molin, Marta; Paradisi, Cristina

2013-01-02

Oxidation mechanisms in air nonthermal plasma (NTP) at room temperature and atmospheric pressure were investigated in a corona reactor energized by +dc, -dc, or +pulsed high voltage.. The two bromomethanes CF(2)Br(2) and CH(2)Br(2) were chosen as model organic pollutants because of their very different reactivities with OH radicals. Thus, they served as useful mechanistic probes: they respond differently to the presence of humidity in the air and give different products. By FT-IR analysis of the postdischarge gas the following products were detected and quantified: CO(2) and CO in the case of CH(2)Br(2), CO(2) and F(2)C ═ O in the case of CF(2)Br(2). F(2)C ═ O is a long-lived oxidation intermediate due to its low reactivity with atmospheric radicals. It is however removed from the NTP processed gas by passage through a water scrubber resulting in hydrolysis to CO(2) and HF. Other noncarbon containing products of the discharge were also monitored by FT-IR analysis, including HNO(3) and N(2)O. Ozone, an important product of air NTP, was never detected in experiments with CF(2)Br(2) and CH(2)Br(2) because of the highly efficient ozone depleting cycles catalyzed by BrOx species formed from the bromomethanes. It is concluded that, regardless of the type of corona applied, CF(2)Br(2) reacts in air NTP via a common intermediate, the CF(2)Br radical. The possible reactions leading to this radical are discussed, including, for -dc activation, charge exchange with O(2)(-), a species detected by APCI mass spectrometry.

The obesity-induced transcriptional regulator TRIP-Br2 mediates visceral fat endoplasmic reticulum stress-induced inflammation.

Science.gov (United States)

Qiang, Guifen; Kong, Hyerim Whang; Fang, Difeng; McCann, Maximilian; Yang, Xiuying; Du, Guanhua; Blüher, Matthias; Zhu, Jinfang; Liew, Chong Wee

2016-04-25

The intimate link between location of fat accumulation and metabolic disease risk and depot-specific differences is well established, but how these differences between depots are regulated at the molecular level remains largely unclear. Here we show that TRIP-Br2 mediates endoplasmic reticulum (ER) stress-induced inflammatory responses in visceral fat. Using in vitro, ex vivo and in vivo approaches, we demonstrate that obesity-induced circulating factors upregulate TRIP-Br2 specifically in visceral fat via the ER stress pathway. We find that ablation of TRIP-Br2 ameliorates both chemical and physiological ER stress-induced inflammatory and acute phase response in adipocytes, leading to lower circulating levels of inflammatory cytokines. Using promoter assays, as well as molecular and pharmacological experiments, we show that the transcription factor GATA3 is responsible for the ER stress-induced TRIP-Br2 expression in visceral fat. Taken together, our study identifies molecular regulators of inflammatory response in visceral fat that-given that these pathways are conserved in humans-might serve as potential therapeutic targets in obesity.

Genética de coffea VI: independência dos fatores xc xc (xanthocarpa e br br (bronze em coffea arabica L.

Directory of Open Access Journals (Sweden)

C. A. Krug

1942-01-01

Full Text Available Em artigos anteriores (1, 2 os autores demonstraram que a cor amarela dos frutos e a coloração bronzeada das folhas novas são, em Coffea arabica L, controladas, cada uma, por um único par de fatores genéticos (respectivamente xc xc e Br Br. Os híbridos F1 no primeiro caso com plantas de frutos vermelhos, e no segundo com plantas de folhas novas verdes, demonstraram tratar-se de casos em que há dominância incompleta nesta geração, os frutos híbridos possuindo uma coloração vermelho clara e as folhas novas se apresentando com uma tonalidade bronze clara. Como algumas das hibridações realizadas envolviam, ao mesmo tempo, os dois caracteres em questão, apresentou-se a oportunidade para constatar se havia ou não independência entre os dois pares de fatores que controlam estes caracteres. Neste artigo apresentam-se os resultados das observações realizadas, tanto em diversas populações de F2 como também em dois back-crosses. Os dados confirmam plenamente a hipótese estabelecida, isto é, da independência entre os dois pares de fatores em questão (xc xc e Br Br. Este fato era esperado à vista do número relativamente elevado de cromosômios nas variedades cruzadas (2n = 44.In two previous publications (1,2 the authors demonstrated that in Coffea arabica L. yellow fruit color and bronze color of young leaves are each controled by one pair of genes (respectively xc xc and Br Br. The F1 hybrids, in the first instance between plants with yellow and red fruits and in the second instance between plants with bronze and green colored young leaves, showed incomplete dominance of both characters, the F1 fruits being of a light red color and the F1 young leaves of a light bronze one. As some of the crosses involved both pairs of genes, it was possible to find out wether they are linked or independent. In the present article the authors are publishing the results obtained with several F2 populations and also with 2 types of back crosses

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...

Hybridization of Single Nanocrystals of Cs4PbBr6 and CsPbBr3

OpenAIRE

Weerd, Chris de; Lin, Junhao; Gomez, Leyre; Fujiwara, Yasufumi; Suenaga, Kazutomo; Gregorkiewicz, Tom

2017-01-01

Nanocrystals of all-inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, I) feature high absorption and efficient narrow-band emission which renders them promising for future generation of photovoltaic and optoelectronic devices. Colloidal ensembles of these nanocrystals can be conveniently prepared by chemical synthesis. However, in the case of CsPbBr3, its synthesis can also yield nanocrystals of Cs4PbBr6 and the properties of the two are easily confused. Here, we investigate in de...

Novo método espectrofotométrico para determinação de Hg (II em amostras de peixe New spectrophotometric method for the determination of Hg (II in fish samples

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Lorena Carvalho Martiniano

2008-06-01

Full Text Available Um novo método espectrofotométrico simples, sensível e com boa seletividade é apresentado para a determinação rápida de mercúrio (II em nível de traços com 2-mercapto-5-metilbenzilimidazol (MMBI como um novo reagente espectrofotométrico (lambda max = 320 nm, em um meio aquoso ligeiramente alcalino (tampão Britton-Robinson (BR 0,04 M, pH 8,0. A reação é instantânea e a absorbância permanece estável por mais de 24 horas. O coeficiente de absorção molar encontrado foi de 2,71 x 10(4 L mol-1 cm-1. A composição estequiométrica do complexo é de 1:1 (Hg:MMBI. Considerável excesso dos íons cobre, zinco, chumbo e cádmio não interfere na determinação. O método desenvolvido permitiu a determinação de mercúrio na faixa de 2 x 10-6 a 4 x 10-5 mol.L-1 com boa precisão e exatidão, e o limite de detecção para Hg foi de 9,9 x 10-7 mol.L-1. O método foi aplicado com sucesso a amostras de peixe e os resultados foram avaliados com o clássico método de espectrometria de absorção atômica (EAA. Os desvios padrão relativos para as amostras analisadas foram de 7,2 e 33% (n = 5, enquanto os erros foram de 1,63 e 11,6. O método mostrou-se sensível, seletivo e foi aplicado para a determinação de mercúrio em amostras de peixe com resultados satisfatórios.A simple, sensitive and selective spectrophotmetric method is presented for the rapid determination of mercury (II at trace levels using 2-mercapto-5-methylbenzimidazole (MMBI as a new spectrophotometric reagent (lambdamax = 320 nm in a slightly basic (0.04 M Britton-Robinson (BR buffer, pH 8.0 aqueous solution. The reaction is instantaneous and the absorbance remains stable for over 24 hours. The average molar absorption coefficient was found to be 2.71 x 10(4 L mol-1 cm-1. The stoichiometric composition of the chelate is 1:1 (Hg:MMBI. Considerable excesses of copper, zinc, lead and cadmium do not interfere in the determination. The method developed allowed the

Simple and green synthesis of piperazine-grafted reduced graphene oxide and its application for the detection of Hg(II)

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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.

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)

Origin of the Substitution Mechanism for the Binding of Organic Ligands on the Surface of CsPbBr3 Perovskite Nanocubes.

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Ravi, Vikash Kumar; Santra, Pralay K; Joshi, Niharika; Chugh, Jeetender; Singh, Sachin Kumar; Rensmo, Håkan; Ghosh, Prasenjit; Nag, Angshuman

2017-10-19

Optoelectronic properties of CsPbBr 3 perovskite nanocubes (NCs) depend strongly on the interaction of the organic passivating molecules with the inorganic crystal. To understand this interaction, we employed a combination of synchrotron-based X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR) spectroscopy, and first-principles density functional theory (DFT)-based calculations. Variable energy XPS elucidated the internal structure of the inorganic part in a layer-by-layer fashion, whereas NMR characterized the organic ligands. Our experimental results confirm that oleylammonium ions act as capping ligands by substituting Cs + ions from the surface of CsPbBr 3 NCs. DFT calculations shows that the substitution mechanism does not require much energy for surface reconstruction and, in contrast, stabilizes the nanocrystal by the formation of three hydrogen bonds between the -NH 3 + moiety of oleylammonium and surrounding Br - on the surface of NCs. This substitution mechanism and its origin are in stark contrast to the usual adsorption of organic ligands on the surface of typical NCs.

Intracellular Hg(0) Oxidation in Desulfovibrio desulfuricans ND132.

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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.

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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).

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...

Hexakis(1-methyl-1H-imidazole-κN3cobalt(II dibromide dihydrate

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Rufu Yao

2009-02-01

Full Text Available The asymmetric unit of the title compound, [Co(C4H6N26]Br2·2H2O, contains one-half of the centrosymmetric cation, one Br atom and one water molecule. The CoII atom, lying on an inversion center, has a distorted octahedral geometry, defined by six N atoms from six 1-methylimidazole ligands. In the crystal structure, intra- and intermolecular O—H...Br hydrogen bonds link pairs of uncoordinated water molecules and bromide anions.