Is halogen content the most important factor in the removal of halogenated trace organics by MBR treatment?

Science.gov (United States)

Hai, Faisal I; Tadkaew, Nichanan; McDonald, James A; Khan, Stuart J; Nghiem, Long D

2011-05-01

This study investigated the relationship between physicochemical properties (namely halogen content and hydrophobicity) of halogenated trace organics and their removal efficiencies by a laboratory scale membrane bioreactor (MBR) under stable operating conditions. The reported results demonstrated a combined effect of halogen content and hydrophobicity on the removal. Compounds with high halogen content (>0.3) were well removed (>85%) when they possessed high hydrophobicity (Log D>3.2), while those with lower Log D values were also well removed if they had low halogen content (BIOWIN index (which is based on only biodegradation) or a more specific index such as the halogen content (which captures a chemical aspect) appeared insufficient to predict the removal efficiency of halogenated compounds in MBR. Experimental data confirmed that the ratio of halogen content and Log D, which incorporates two important physico-chemical properties, is comparatively more suitable. Copyright © 2011 Elsevier Ltd. All rights reserved.

Organohalide respiration in pristine environments: implications for the natural halogen cycle.

Science.gov (United States)

Atashgahi, Siavash; Häggblom, Max M; Smidt, Hauke

2018-03-01

Halogenated organic compounds, also termed organohalogens, were initially considered to be of almost exclusively anthropogenic origin. However, over 5000 naturally synthesized organohalogens are known today. This has also fuelled the hypothesis that the natural and ancient origin of organohalogens could have primed development of metabolic machineries for their degradation, especially in microorganisms. Among these, a special group of anaerobic microorganisms was discovered that could conserve energy by reducing organohalogens as terminal electron acceptor in a process termed organohalide respiration. Originally discovered in a quest for biodegradation of anthropogenic organohalogens, these organohalide-respiring bacteria (OHRB) were soon found to reside in pristine environments, such as the deep subseafloor and Arctic tundra soil with limited/no connections to anthropogenic activities. As such, accumulating evidence suggests an important role of OHRB in local natural halogen cycles, presumably taking advantage of natural organohalogens. In this minireview, we integrate current knowledge regarding the natural origin and occurrence of industrially important organohalogens and the evolution and spread of OHRB, and describe potential implications for natural halogen and carbon cycles. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Iron Coordination and Halogen-Bonding Assisted Iodosylbenzene Activation

DEFF Research Database (Denmark)

Wegeberg, Christina; Poulsen de Sousa, David; McKenzie, Christine

catalytic mixtures using soluble terminal oxygen transfer agents. Isolation of a reactive iron-terminal oxidant adduct, an unique Fe(III)-OIPh complex, is facilitated by strong stabilizing supramolecular halogen-bonding. L3-edge XANES suggests +1.6 for the average oxidation state for the iodine atom3......The iron complex of the hexadentate ligand N,N,N'-tris(2-pyridylmethyl)ethylendiamine-N'-acetate (tpena) efficiently catalyzes selective oxidations of electron-rich olefins and sulfides by insoluble iodosylbenzene (PhIO). Surprisingly, these reactions are faster and more selective than homogenous...... in the iron(III)-coordinated PhIO. This represents a reduction of iodine relative to the original “hypervalent” (+3) PhIO. The equivalent of electron density must be removed from the {(tpena)Fe(III)O} moiety, however Mössbauer spectroscopy shows that the iron atom is not high valent....

Halogenated arsenenes as Dirac materials

International Nuclear Information System (INIS)

Tang, Wencheng; Sun, Minglei; Ren, Qingqiang; Wang, Sake; Yu, Jin

2016-01-01

Highlights: • We have revealed the presence of Dirac cone in fully-halogenated arsenene compounds. • All fully-halogenated arsenene except As_2I_2 would spontaneously form and stable in defending the thermal fluctuation in room temperature. - Abstract: Arsenene is the graphene-like arsenic nanosheet, which has been predicted very recently [S. Zhang, Z. Yan, Y. Li, Z. Chen, and H. Zeng, Angewandte Chemie, 127 (2015) 3155–3158]. Using first-principles calculations, we systematically investigate the structures and electronic properties of fully-halogenated arsenenes. Formation energy analysis reveals that all the fully-halogenated arsenenes except iodinated arsenene are energetically favorable and could be synthesized. We have revealed the presence of Dirac cone in fully-halogenated arsenene compounds. They may have great potential applications in next generation of high-performance devices.

Dissociative Photoionization of 1-Halogenated Silacyclohexanes: Silicon Traps the Halogen.

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Bodi, Andras; Sigurdardottir, Katrin Lilja; Kvaran, Ágúst; Bjornsson, Ragnar; Arnason, Ingvar

2016-11-23

The threshold photoelectron spectra and threshold photoionization mass spectra of 1-halogenated-1-silacyclohexanes, for the halogens X = F, Cl, Br, and I, have been obtained using synchrotron vacuum ultraviolet radiation and photoelectron photoion coincidence spectroscopy. As confirmed by a similar ionization onset and density functional theory molecular orbitals, the ionization to the ground state is dominated by electron removal from the silacyclohexane ring for X = F, Cl, and Br, and from the halogen lone pair for X = I. The breakdown diagrams show that the dissociative photoionization mechanism is also different for X = I. Whereas the parent ions decay by ethylene loss for X = F to Br in the low-energy regime, the iodine atom is lost for X = I. The first step is followed by a sequential ethylene loss at higher internal energies in each of the compounds. It is argued that the tendency of silicon to lower bond angles stabilizes the complex cation in which C 2 H 4 is η 2 -coordinated to it, and which precedes ethylene loss. Together with the relatively strong silicon-halogen bonds and the increased inductive effect of the silacyclohexane ring in stabilizing the cation, this explains the main differences observed in the fragmentation of the halogenated silacyclohexane and halogenated cyclohexane ions. The breakdown diagrams have been modeled taking into account slow dissociations at threshold and the resulting kinetic shift. The 0 K appearance energies have been obtained to within 0.08 eV for the ethylene loss for X = F to Br (10.56, 10.51, and 10.51 eV, respectively), the iodine atom loss for X = I (10.11 eV), the sequential ethylene loss for X = F to I (12.29, 12.01, 11.94, and 11.86 eV, respectively), and the minor channels of H loss for X = F (10.56 eV) and propylene loss in X = Cl (also at 10.56 eV). The appearance energies for the major channels likely correspond to the dissociative photoionization reaction energy.

Boiling points of halogenated ethanes: an explanatory model implicating weak intermolecular hydrogen-halogen bonding.

Science.gov (United States)

Beauchamp, Guy

2008-10-23

This study explores via structural clues the influence of weak intermolecular hydrogen-halogen bonds on the boiling point of halogenated ethanes. The plot of boiling points of 86 halogenated ethanes versus the molar refraction (linked to polarizability) reveals a series of straight lines, each corresponding to one of nine possible arrangements of hydrogen and halogen atoms on the two-carbon skeleton. A multiple linear regression model of the boiling points could be designed based on molar refraction and subgroup structure as independent variables (R(2) = 0.995, standard error of boiling point 4.2 degrees C). The model is discussed in view of the fact that molar refraction can account for approximately 83.0% of the observed variation in boiling point, while 16.5% could be ascribed to weak C-X...H-C intermolecular interactions. The difference in the observed boiling point of molecules having similar molar refraction values but differing in hydrogen-halogen intermolecular bonds can reach as much as 90 degrees C.

Evidence for Interfacial Halogen Bonding.

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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.

Halogen bond: a long overlooked interaction.

Science.gov (United States)

Cavallo, Gabriella; Metrangolo, Pierangelo; Pilati, Tullio; Resnati, Giuseppe; Terraneo, Giancarlo

2015-01-01

Because of their high electronegativity, halogen atoms are typically considered, in most of their derivatives, as sites of high electron density and it is commonly accepted that they can form attractive interactions by functioning as the electron donor site (nucleophilic site). This is the case when they work as hydrogen bond acceptor sites. However, the electron density in covalently bound halogens is anisotropically distributed. There is a region of higher electron density, accounting for the ability of halogens to function as electron donor sites in attractive interactions, and a region of lower electron density where the electrostatic potential is frequently positive (mainly in the heavier halogens). This latter region is responsible for the ability of halogen atoms to function as the electron-acceptor site (electrophilic site) in attractive interactions formed with a variety of lone pair-possessing atoms, anions, and π-systems. This ability is quite general and is shown by a wide diversity of halogenated compounds (e.g., organohalogen derivatives and dihalogens). According to the definition proposed by the International Union of Pure and Applied Chemistry, any attractive interactions wherein the halogen atom is the electrophile is named halogen bond (XB). In this chapter, it is discussed how the practice and the concept of XB developed and a brief history of the interaction is presented. Papers (either from the primary or secondary literature) which have reported major experimental findings in the field or which have given important theoretical contributions for the development of the concept are recollected in order to trace how a unifying and comprehensive categorization emerged encompassing all interactions wherein halogen atoms function as the electrophilic site.

Halogen bonding in solution: thermodynamics and applications.

Science.gov (United States)

Beale, Thomas M; Chudzinski, Michael G; Sarwar, Mohammed G; Taylor, Mark S

2013-02-21

Halogen bonds are noncovalent interactions in which covalently bound halogens act as electrophilic species. The utility of halogen bonding for controlling self-assembly in the solid state is evident from a broad spectrum of applications in crystal engineering and materials science. Until recently, it has been less clear whether, and to what extent, halogen bonding could be employed to influence conformation, binding or reactivity in the solution phase. This tutorial review summarizes and interprets solution-phase thermodynamic data for halogen bonding interactions obtained over the past six decades and highlights emerging applications in molecular recognition, medicinal chemistry and catalysis.

Long-term Studies of Marine Halogen Release

Science.gov (United States)

Tschritter, J.; Holla, R.; Frieß, U.; Platt, U.

2009-04-01

Institute of Enviromental Physics, Heidelberg, Germany. Long term measurements of atmospheric trace gases using multi-axis DOAS instruments are pursued at the new SOLAS observatory on the island of Sao Vicente, (Cape Verde). This research is part of the SOPRAN (Surface Ocean Processes in the ANthropocene) project (Fördernummer:03F0462F). Reactive halogen species (RHS) such as bromine- and iodine- containing species play major roles in the chemistry of ozone in both the troposphere and lower stratosphere and thus possibly influence the ozone budget on a global scale. In addition iodine-species emitted from the ocean surface have been shown to be responsible for the production of new atmospheric particles in the marine boundary layer. This may have an effect on cloud formation and radiation transfer on local and global scales. Long term measurements of RHS abundances will help to identify their key regions and processes for formation. A new long term Multi-MAX-DOAS instrument has been installed at the SOLAS observatory on the island of Sao Vicente, (Cape Verde). The main focus of these unique measurements is the investigation of reactive halogen chemistry in the subtropical marine boundary layer based on measurements of BrO, IO, and possibly OIO. Because of its wide spectral range also the use for O4-retrievals to gain aerosol profiles is possible. IO has been detected with mixing ratios up to 1.3 ppt. For BrO an upper limit of 2 ppt could be determined.

Organic halogens in landfill leachates

DEFF Research Database (Denmark)

Grøn, C.; Christensen, J. B.; Jensen, Dorthe Lærke

2000-01-01

Using a group parameter, total organic halogens (TOX), high TOX concentrations were found in leachates and leachate contaminated groundwaters at two Danish mixed sanitary and hazardous waste sites. With commonly used screening procedures for organic contaminants, the individual halogenated organi...

Attosecond Time Delay in Photoionization of Noble-Gas and Halogen Atoms

Directory of Open Access Journals (Sweden)

Liang-Wen Pi

2018-02-01

Full Text Available Ultrafast processes are now accessible on the attosecond time scale due to the availability of ultrashort XUV laser pulses. Noble-gas and halogen atoms remain important targets due to their giant dipole resonance and Cooper minimum. Here, we calculate photoionization cross section, asymmetry parameter and Wigner time delay using the time-dependent local-density approximation (TDLDA, which includes the electron correlation effects. Our results are consistent with experimental data and other theoretical calculations. The asymmetry parameter provides an extra layer of access to the phase information of the photoionization processes. We find that halogen atoms bear a strong resemblance on cross section, asymmetry parameter and time delay to their noble-gas neighbors. Our predicted time delay should provide a guidance for future experiments on those atoms and related molecules.

Biogeochemistry of Halogenated Hydrocarbons

Science.gov (United States)

Adriaens, P.; Gruden, C.; McCormick, M. L.

2003-12-01

Halogenated hydrocarbons originate from both natural and industrial sources. Whereas direct anthropogenic emissions to the atmosphere and biosphere are often easy to assess, particularly when they are tied to major industrial activities, the attribution of emissions to other human activities (e.g., biomass burning), diffuse sources (e.g., atmospheric discharge, run off), and natural production (e.g., soils, fungi, algae, microorganisms) are difficult to quantify. The widespread occurrence of both alkyl and aryl halides in groundwater, surface water, soils, and various trophic food chains, even those not affected by known point sources, suggests a substantial biogeochemical cycling of these compounds (Wania and Mackay, 1996; Adriaens et al., 1999; Gruden et al., 2003). The transport and reactive fate mechanisms controlling their reactivity are compounded by the differences in sources of alkyl-, aryl-, and complex organic halides, and the largely unknown impact of biogenic processes, such as enzymatically mediated halogenation of organic matter, fungal production of halogenated hydrocarbons, and microbial or abiotic transformation reactions (e.g., Asplund and Grimvall, 1991; Gribble, 1996; Watling and Harper, 1998; Oberg, 2002). The largest source may be the natural halogenation processes in the terrestrial environment, as the quantities detected often exceed the amount that can be explained by human activities in the surrounding areas ( Oberg, 1998). Since biogeochemical processes result in the distribution of a wide range of halogenated hydrocarbon profiles, altered chemical structures, and isomer distributions in natural systems, source apportionment (or environmental forensics) can often only be resolved using multivariate statistical methods (e.g., Goovaerts, 1998; Barabas et al., 2003; Murphy and Morrison, 2002).This chapter will describe the widespread occurrence of halogenated hydrocarbons, interpret their distribution and biogeochemical cycling in light of

Studies on halogen quenching through the Stern-Volmer plot

International Nuclear Information System (INIS)

Takiue, Makoto; Ishikawa, Hiroaki.

1978-01-01

The quenching effect for halogenated benzenes, methanes and ethanes have been investigated. The halogen quenching was accurately measured using the internal conversion electrons emitted from 113 Sn-sup(113m)In. From the quenching constants determined by the Stern-Volmer plots with respect to various halogen quenchers, the following results have been obtained. (1) The quenching constants increase with the number of halogen substituents, so as linearly in halogenated benzenes and exponentially in halogenated methanes and ethanes. Even the isomers of halogenides have different quenching constants. (2) There is a linearity between logarithm of the quenching constant and a polarographic half-wave reduction potential. (3) Electron excitation provides larger quenching constants than UV excitation for halogenated methanes. Based on these results, the mechanism of halogen quenching have been discussed in connection with the exciplex formation. (auth.)

Independent Evolution of Six Families of Halogenating Enzymes.

Science.gov (United States)

Xu, Gangming; Wang, Bin-Gui

2016-01-01

Halogenated natural products are widespread in the environment, and the halogen atoms are typically vital to their bioactivities. Thus far, six families of halogenating enzymes have been identified: cofactor-free haloperoxidases (HPO), vanadium-dependent haloperoxidases (V-HPO), heme iron-dependent haloperoxidases (HI-HPO), non-heme iron-dependent halogenases (NI-HG), flavin-dependent halogenases (F-HG), and S-adenosyl-L-methionine (SAM)-dependent halogenases (S-HG). However, these halogenating enzymes with similar biological functions but distinct structures might have evolved independently. Phylogenetic and structural analyses suggest that the HPO, V-HPO, HI-HPO, NI-HG, F-HG, and S-HG enzyme families may have evolutionary relationships to the α/β hydrolases, acid phosphatases, peroxidases, chemotaxis phosphatases, oxidoreductases, and SAM hydroxide adenosyltransferases, respectively. These halogenating enzymes have established sequence homology, structural conservation, and mechanistic features within each family. Understanding the distinct evolutionary history of these halogenating enzymes will provide further insights into the study of their catalytic mechanisms and halogenation specificity.

Passivation of quartz for halogen-containing light sources

Science.gov (United States)

Falkenstein, Zoran

1999-01-01

Lifetime of halogen containing VUV, UV, visible or IR light sources can be extended by passivating the quartz or glass gas containers with halogens prior to filling the quartz with the halogen and rare gas mixtures used to produce the light.

METHOD FOR PRODUCING ISOTOPIC METHANES AND PARTIALLY HALOGENATED DERIVATIVES THEROF

Science.gov (United States)

Frazer, J.W.

1959-08-18

A method is given for producing isotopic methanes and/ or partially halogenated derivatives. Lithium hydride, deuteride, or tritide is reacted with a halogenated methane or with a halogenated methane in combination with free halogen. The process is conveniently carried out by passing a halogenated methane preferably at low pressures or in an admixture with an inert gas through a fixed bed of finely divided lithium hydride heated initially to temperatures of 100 to 200 deg C depending upon the halogenated methane used.

Organic halogens in spruce forest throughfall

DEFF Research Database (Denmark)

Öberg, G.; Johansen, C.; Grøn, C.

1998-01-01

. No relationship between the position of the collectors and the forest edge or dominating wind-direction was found, suggesting that dry deposition was not a major source. The concentration of organic halogens was related to that of organic carbon and decreased from the tree-trunk and outwards. In addition......, the concentrations were higher during the growing season than during the dormant season. This indicates that the major part of the organic carbon and organic halogens in spruce forest throughfall originates from canopy leachates or other internal sources. (C) 1998 Elsevier Science Ltd.......Deposition of dissolved organic halogens by throughfall was determined in a small spruce forest site in Denmark (56 degrees 28'N, 8 degrees 24'E). The mean annual deposition of dissolved organic halogens was 377 g ha(-1)yr(-1), and larger than the general deposition by precipitation...

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.

Experimental and computational evidence of halogen bonds involving astatine

Science.gov (United States)

Guo, Ning; Maurice, Rémi; Teze, David; Graton, Jérôme; Champion, Julie; Montavon, Gilles; Galland, Nicolas

2018-03-01

The importance of halogen bonds—highly directional interactions between an electron-deficient σ-hole moiety in a halogenated compound and an acceptor such as a Lewis base—is being increasingly recognized in a wide variety of fields from biomedicinal chemistry to materials science. The heaviest halogens are known to form stronger halogen bonds, implying that if this trend continues down the periodic table, astatine should exhibit the highest halogen-bond donating ability. This may be mitigated, however, by the relativistic effects undergone by heavy elements, as illustrated by the metallic character of astatine. Here, the occurrence of halogen-bonding interactions involving astatine is experimentally evidenced. The complexation constants of astatine monoiodide with a series of organic ligands in cyclohexane solution were derived from distribution coefficient measurements and supported by relativistic quantum mechanical calculations. Taken together, the results show that astatine indeed behaves as a halogen-bond donor—a stronger one than iodine—owing to its much more electrophilic σ-hole.

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.

Removal of Intermediate Aromatic Halogenated DBPs by Activated Carbon Adsorption: A New Approach to Controlling Halogenated DBPs in Chlorinated Drinking Water.

Science.gov (United States)

Jiang, Jingyi; Zhang, Xiangru; Zhu, Xiaohu; Li, Yu

2017-03-21

During chlorine disinfection of drinking water, chlorine may react with natural organic matter (NOM) and bromide ion in raw water to generate halogenated disinfection byproducts (DBPs). To mitigate adverse effects from DBP exposure, granular activated carbon (GAC) adsorption has been considered as one of the best available technologies for removing NOM (DBP precursor) in drinking water treatment. Recently, we have found that many aromatic halogenated DBPs form in chlorination, and they act as intermediate DBPs to decompose and form commonly known DBPs including trihalomethanes and haloacetic acids. In this work, we proposed a new approach to controlling drinking water halogenated DBPs by GAC adsorption of intermediate aromatic halogenated DBPs during chlorination, rather than by GAC adsorption of NOM prior to chlorination (i.e., traditional approach). Rapid small-scale column tests were used to simulate GAC adsorption in the new and traditional approaches. Significant reductions of aromatic halogenated DBPs were observed in the effluents with the new approach; the removals of total organic halogen, trihalomethanes, and haloacetic acids by the new approach always exceeded those by the traditional approach; and the effluents with the new approach were considerably less developmentally toxic than those with the traditional approach. Our findings indicate that the new approach is substantially more effective in controlling halogenated DBPs than the traditional approach.

Mid-latitude Ozone Depletion Events Caused by Halogens from the Great Salt Lake in Utah

Science.gov (United States)

Fibiger, D. L.; Goldberger, L.; Womack, C.; McDuffie, E. E.; Dube, W. P.; Franchin, A.; Middlebrook, A. M.; Thornton, J. A.; Brown, S. S.

2017-12-01

Halogens are highly reactive chemicals and play an important role in atmospheric chemistry. They can be involved in many cycles which influence the oxidizing capacity of the atmosphere, including through destruction of ozone (O3). While the influence of halogens on O3 is well documented in the arctic, there are very few observations of O3 depletion driven by halogens in the mid-latitudes. To date, the most comprehensive study observed co-occurring plumes of BrO and depleted O3 near the Dead Sea in 1997. During the Utah Wintertime Fine Particulate Study (UWFPS) in winter 2017, simultaneous measurements of a comprehensive suite of halogen measurements by I- chemical ionization mass spectrometry and O3 from cavity ring-down spectroscopy, both at 1-second time resolution, were taken on a NOAA Twin Otter Aircraft over the Great Salt Lake and in the surrounding valleys. Many O3 depletion events were observed over the lake with O3 values sometimes below the instrument detection limit of 0.5 ppbv. Corresponding increases in BrO and/or ClO were observed. Many of these events were caused by extremely high levels of halogens (up to 1 ppmv Cl2) emitted from the U.S. Magnesium plant on the edge of the lake. The O3 depletion caused by U.S. Magnesium was usually isolated to a distinct vertical layer, but in other cases O3 depletion was vertically mixed and the origin of halogen activation was not immediately clear. The most complete O3 depletion was observed over the lake, but there were smaller events of a few ppbv observed in the adjacent valleys, including the highly populated Salt Lake Valley, with corresponding plumes of BrO and ClO, due to transport from the lake. Additionally, meteorology played a role in the observed O3 depletion. The strongest O3 depletion was observed during inversion events, when there is a low boundary layer and little mixing out of the air above the lake. During non-inversion conditions, only small depletions were observed, covering a much smaller

The halogen bond: Nature and applications

Science.gov (United States)

Costa, Paulo J.

2017-10-01

The halogen bond, corresponding to an attractive interaction between an electrophilic region in a halogen (X) and a nucleophile (B) yielding a R-X⋯B contact, found applications in many fields such as supramolecular chemistry, crystal engineering, medicinal chemistry, and chemical biology. Their large range of applications also led to an increased interest in their study using computational methods aiming not only at understanding the phenomena at a fundamental level, but also to help in the interpretation of results and guide the experimental work. Herein, a succinct overview of the recent theoretical and experimental developments is given starting by discussing the nature of the halogen bond and the latest theoretical insights on this topic. Then, the effects of the surrounding environment on halogen bonds are presented followed by a presentation of the available method benchmarks. Finally, recent experimental applications where the contribution of computational chemistry was fundamental are discussed, thus highlighting the synergy between the lab and modeling techniques.

Model study of multiphase DMS oxidation with a focus on halogens

Directory of Open Access Journals (Sweden)

R. von Glasow

2004-01-01

Full Text Available We studied the oxidation of dimethylsulfide (DMS in the marine boundary layer (MBL with a one-dimensional numerical model and focused on the influence of halogens. Our model runs show that there is still significant uncertainty about the end products of the DMS addition pathway, which is especially caused by uncertainty in the product yield of the reaction of the intermediate product methyl sulfinic acid (MSIA with OH. BrO strongly increases the importance of the addition branch in the oxidation of DMS even when present at mixing ratios smaller than 0.5pmol mol-1. The inclusion of halogen chemistry leads to higher DMS oxidation rates and smaller DMS to SO2 conversion efficiencies. The DMS to SO2 conversion efficiency is also drastically reduced under cloudy conditions. In cloud-free model runs between 5 and 15% of the oxidized DMS reacts further to particulate sulfur, in cloudy runs this fraction is almost 100%. Sulfate production by HOClaq and HOBraq is important in cloud droplets even for small Br- deficits and related small gas phase halogen concentrations. In general, more particulate sulfur is formed when halogen chemistry is included. A possible enrichment of HCO3- in fresh sea salt aerosol would increase pH values enough to make the reaction of S(IV* (=SO2,aq+HSO3-+SO32- with O3 dominant for sulfate production. It leads to a shift from methyl sulfonic acid (MSA to non-sea salt sulfate (nss-SO42- production but increases the total nss-SO42- only somewhat because almost all available sulfur is already oxidized to particulate sulfur in the base scenario. We discuss how realistic this is for the MBL. We found the reaction MSAaq+OH to contribute about 10% to the production of nss-SO42- in clouds. It is unimportant for cloud-free model runs. Overall we find that the presence of halogens leads to processes that decrease the albedo of stratiform clouds in the MBL.

Enzymatic Halogenation and Dehalogenation Reactions: Pervasive and Mechanistically Diverse.

Science.gov (United States)

Agarwal, Vinayak; Miles, Zachary D; Winter, Jaclyn M; Eustáquio, Alessandra S; El Gamal, Abrahim A; Moore, Bradley S

2017-04-26

Naturally produced halogenated compounds are ubiquitous across all domains of life where they perform a multitude of biological functions and adopt a diversity of chemical structures. Accordingly, a diverse collection of enzyme catalysts to install and remove halogens from organic scaffolds has evolved in nature. Accounting for the different chemical properties of the four halogen atoms (fluorine, chlorine, bromine, and iodine) and the diversity and chemical reactivity of their organic substrates, enzymes performing biosynthetic and degradative halogenation chemistry utilize numerous mechanistic strategies involving oxidation, reduction, and substitution. Biosynthetic halogenation reactions range from simple aromatic substitutions to stereoselective C-H functionalizations on remote carbon centers and can initiate the formation of simple to complex ring structures. Dehalogenating enzymes, on the other hand, are best known for removing halogen atoms from man-made organohalogens, yet also function naturally, albeit rarely, in metabolic pathways. This review details the scope and mechanism of nature's halogenation and dehalogenation enzymatic strategies, highlights gaps in our understanding, and posits where new advances in the field might arise in the near future.

Molecular activation analysis for organo-halogen contaminants in yogurt

International Nuclear Information System (INIS)

Zhang Hong; Chai Zhifang

2004-01-01

The concentrations of total halogen (TX), extractable organo-halogen (EOX), extractable persistent organo-halogen (EPOX), organo-chlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in 18 different yogurt specimens of 14 brands from Beijing, Tianjin, Shanghai, Guangzhou and Shijiazhuang were determined by epithermal neutron activation analysis (ENAA), molecular activation analysis (MAA) and GC-Mass Spectrometry (GC-MS), respectively. The results indicated that the halogen in yogurt mainly existed as inorganic species and non-extractable organo-halogen compounds. About 1/3 to 1/4 of EOX was EPOX. Further, EOCl and EPOCl were the main organo-halogen species in yogurt. The average concentration of the unknown organo-chlorine was 96% of the EPOCl. HCHs and DDTs were still the main contaminants of OCPs in the yogurt of interest. Also, PCB202, PCB103 and PCB208 were the main contaminants of PCBs. (authors)

FIELD SCREENING FOR HALOGENATED VOLATILE ORGANIC COMPOUNDS

Energy Technology Data Exchange (ETDEWEB)

John F. Schabron; Joseph F. Rovani Jr.; Theresa M. Bomstad

2002-06-01

Western Research Institute (WRI) initiated exploratory work towards the development of new field screening methodology and a test kit to measure halogenated volatile organic compounds (VOCs) in the field. Heated diode and corona discharge sensors are commonly used to detect leaks of refrigerants from air conditioners, freezers, and refrigerators. They are both selective to the presence of carbon-halogen bonds. Commercially available heated diode and corona discharge leak detectors were procured and evaluated for halogenated VOC response. The units were modified to provide a digital readout of signal related to VOC concentration. Sensor response was evaluated with carbon tetrachloride and tetrachloroethylene (perchloroethylene, PCE), which represent halogenated VOCs with and without double bonds. The response characteristics were determined for the VOCs directly in headspace in Tedlar bag containers. Quantitation limits in air were estimated. Potential interferences from volatile hydrocarbons, such as toluene and heptane, were evaluated. The effect of humidity was studied also. The performance of the new devices was evaluated in the laboratory by spiking soil samples and monitoring headspace for halogenated VOCs. A draft concept of the steps for a new analytical method was outlined. The results of the first year effort show that both devices show potential utility for future analytical method development work towards the goal of developing a portable test kit for screening halogenated VOCs in the field.

Halogens in chondritic meteorites and terrestrial accretion

Science.gov (United States)

Clay, Patricia L.; Burgess, Ray; Busemann, Henner; Ruzié-Hamilton, Lorraine; Joachim, Bastian; Day, James M. D.; Ballentine, Christopher J.

2017-11-01

Volatile element delivery and retention played a fundamental part in Earth’s formation and subsequent chemical differentiation. The heavy halogens—chlorine (Cl), bromine (Br) and iodine (I)—are key tracers of accretionary processes owing to their high volatility and incompatibility, but have low abundances in most geological and planetary materials. However, noble gas proxy isotopes produced during neutron irradiation provide a high-sensitivity tool for the determination of heavy halogen abundances. Using such isotopes, here we show that Cl, Br and I abundances in carbonaceous, enstatite, Rumuruti and primitive ordinary chondrites are about 6 times, 9 times and 15-37 times lower, respectively, than previously reported and usually accepted estimates. This is independent of the oxidation state or petrological type of the chondrites. The ratios Br/Cl and I/Cl in all studied chondrites show a limited range, indistinguishable from bulk silicate Earth estimates. Our results demonstrate that the halogen depletion of bulk silicate Earth relative to primitive meteorites is consistent with the depletion of lithophile elements of similar volatility. These results for carbonaceous chondrites reveal that late accretion, constrained to a maximum of 0.5 ± 0.2 per cent of Earth’s silicate mass, cannot solely account for present-day terrestrial halogen inventories. It is estimated that 80-90 per cent of heavy halogens are concentrated in Earth’s surface reservoirs and have not undergone the extreme early loss observed in atmosphere-forming elements. Therefore, in addition to late-stage terrestrial accretion of halogens and mantle degassing, which has removed less than half of Earth’s dissolved mantle gases, the efficient extraction of halogen-rich fluids from the solid Earth during the earliest stages of terrestrial differentiation is also required to explain the presence of these heavy halogens at the surface. The hydropilic nature of halogens, whereby they track

Organic halogen compounds in the environment

International Nuclear Information System (INIS)

1979-07-01

There are 20 research reports on selected problems concerning the analysis, the occurence, and the behaviour of a wide spectrum of organic halogen compounds. The work was carried out in the framework of the project 'Organic Halogen Compounds in the Environment', financed by the BMFT, between 1975 and 1978. (orig.) [de

Process for removal of hydrogen halides or halogens from incinerator gas

Science.gov (United States)

Huang, H.S.; Sather, N.F.

1987-08-21

A process for reducing the amount of halogens and halogen acids in high temperature combustion gas and through their removal, the formation of halogenated organics at lower temperatures, with the reduction being carried out electrochemically by contacting the combustion gas with the negative electrode of an electrochemical cell and with the halogen and/or halogen acid being recovered at the positive electrode.

Computational Tools To Model Halogen Bonds in Medicinal Chemistry.

Science.gov (United States)

Ford, Melissa Coates; Ho, P Shing

2016-03-10

The use of halogens in therapeutics dates back to the earliest days of medicine when seaweed was used as a source of iodine to treat goiters. The incorporation of halogens to improve the potency of drugs is now fairly standard in medicinal chemistry. In the past decade, halogens have been recognized as direct participants in defining the affinity of inhibitors through a noncovalent interaction called the halogen bond or X-bond. Incorporating X-bonding into structure-based drug design requires computational models for the anisotropic distribution of charge and the nonspherical shape of halogens, which lead to their highly directional geometries and stabilizing energies. We review here current successes and challenges in developing computational methods to introduce X-bonding into lead compound discovery and optimization during drug development. This fast-growing field will push further development of more accurate and efficient computational tools to accelerate the exploitation of halogens in medicinal chemistry.

Ozone Depletion in Tropospheric Volcanic Plumes: From Halogen-Poor to Halogen-Rich Emissions

Directory of Open Access Journals (Sweden)

Tjarda J. Roberts

2018-02-01

Full Text Available Volcanic halogen emissions to the troposphere undergo a rapid plume chemistry that destroys ozone. Quantifying the impact of volcanic halogens on tropospheric ozone is challenging, only a few observations exist. This study presents measurements of ozone in volcanic plumes from Kīlauea (HI, USA, a low halogen emitter. The results are combined with published data from high halogen emitters (Mt Etna, Italy; Mt Redoubt, AK, USA to identify controls on plume processes. Ozone was measured during periods of relatively sustained Kīlauea plume exposure, using an Aeroqual instrument deployed alongside Multi-Gas SO2 and H2S sensors. Interferences were accounted for in data post-processing. The volcanic H2S/SO2 molar ratio was quantified as 0.03. At Halema‘uma‘u crater-rim, ozone was close to ambient in the emission plume (at 10 ppmv SO2. Measurements in grounding plume (at 5 ppmv SO2 about 10 km downwind of Pu‘u ‘Ō‘ō showed just slight ozone depletion. These Kīlauea observations contrast with substantial ozone depletion reported at Mt Etna and Mt Redoubt. Analysis of the combined data from these three volcanoes identifies the emitted Br/S as a strong but non-linear control on the rate of ozone depletion. Model simulations of the volcanic plume chemistry highlight that the proportion of HBr converted into reactive bromine is a key control on the efficiency of ozone depletion. This underlines the importance of chemistry in the very near-source plume on the fate and atmospheric impacts of volcanic emissions to the troposphere.

Retention of Halogens in Waste Glass

Energy Technology Data Exchange (ETDEWEB)

Hrma, Pavel R.

2010-05-01

In spite of their potential roles as melting rate accelerators and foam breakers, halogens are generally viewed as troublesome components for glass processing. Of five halogens, F, Cl, Br, I, and At, all but At may occur in nuclear waste. A nuclear waste feed may contain up to 10 g of F, 4 g of Cl, and ≤100 mg of Br and I per kg of glass. The main concern is halogen volatility, producing hazardous fumes and particulates, and the radioactive iodine 129 isotope of 1.7x10^7-year half life. Because F and Cl are soluble in oxide glasses and tend to precipitate on cooling, they can be retained in the waste glass in the form of dissolved constituents or as dispersed crystalline inclusions. This report compiles known halogen-retention data in both high-level waste (HLW) and low-activity waste (LAW) glasses. Because of its radioactivity, the main focus is on I. Available data on F and Cl were compiled for comparison. Though Br is present in nuclear wastes, it is usually ignored; no data on Br retention were found.

Halogen-Mediated Conversion of Hydrocarbons to Commodities.

Science.gov (United States)

Lin, Ronghe; Amrute, Amol P; Pérez-Ramírez, Javier

2017-03-08

Halogen chemistry plays a central role in the industrial manufacture of various important chemicals, pharmaceuticals, and polymers. It involves the reaction of halogens or halides with hydrocarbons, leading to intermediate compounds which are readily converted to valuable commodities. These transformations, predominantly mediated by heterogeneous catalysts, have long been successfully applied in the production of polymers. Recent discoveries of abundant conventional and unconventional natural gas reserves have revitalized strong interest in these processes as the most cost-effective gas-to-liquid technologies. This review provides an in-depth analysis of the fundamental understanding and applied relevance of halogen chemistry in polymer industries (polyvinyl chloride, polyurethanes, and polycarbonates) and in the activation of light hydrocarbons. The reactions of particular interest include halogenation and oxyhalogenation of alkanes and alkenes, dehydrogenation of alkanes, conversion of alkyl halides, and oxidation of hydrogen halides, with emphasis on the catalyst, reactor, and process design. Perspectives on the challenges and directions for future development in this exciting field are provided.

E. S. R. studies of halogenated pyrimidines in. gamma. -irradiated alkaline glasses. [Halogenated uracil bases; bromouridine; bromodeoxyuridine

Energy Technology Data Exchange (ETDEWEB)

Simpson, L D; Zimbrick, J D [Kansas Univ., Lawrence (USA)

1975-11-01

The reactions of mobile electrons (e/sup -//sub m/) and oxygen radical anions (O./sup -/) with halogenated bases and nucleosides have been studied in ..gamma..-irradiated alkaline glasses by e.s.r. and specific halogen-ion electrode techniques. It was shown that electrons react with halogenated uracil bases (XUr where X = Cl, Br, I but not F) by dissociative electron attachment to form uracil-5-yl radicals (U.) and halogen anions. The relative rates of reaction of e/sup -//sub m/ with XUr decreased in the sequence BrUr > ClUr > FUr > IUr. Thermal annealing studies carried out on U. in H/sub 2/O and D/sub 2/O matrices supported the hypothesis that U. in H/sub 2/O hydrates across the 5-6 double bond in the temperature region 135/sup 0/ to 155/sup 0/ K, and deuterates to a much smaller extent in D/sub 2/O at temperatures above 155/sup 0/ K. Studies on bromouridine and bromodeoxyuridine suggested that e/sup -/sub(m) reacts with the base moieties to form U. type radicals which abstract H. from the sugar moieties of adjacent nucleosides.

Scientific conferences: A big hello to halogen bonding

Science.gov (United States)

Erdelyi, Mate

2014-09-01

Halogen bonding connects a wide range of subjects -- from materials science to structural biology, from computation to crystal engineering, and from synthesis to spectroscopy. The 1st International Symposium on Halogen Bonding explored the state of the art in this fast-growing field of research.

Selective C-H Halogenation with a Highly Fluorinated Manganese Porphyrin.

Science.gov (United States)

Li, Gang; Dilger, Andrew K; Cheng, Peter T; Ewing, William R; Groves, John T

2018-01-26

The selective C-H functionalization of aliphatic molecules remains a challenge in organic synthesis. While radical chain halogenation reactions provide efficient access to many halogenated molecules, the use of typical protocols for the selective halogenation of electron-deficient and strained aliphatic molecules is rare. Herein, we report selective C-H chlorination and fluorination reactions promoted by an electron-deficient manganese pentafluorophenyl porphyrin catalyst, Mn(TPFPP)Cl. This catalyst displays superior properties for the aliphatic halogenation of recalcitrant, electron-deficient, and strained substrates with unique regio- and stereoselectivity. UV/Vis analysis during the course of the reaction indicated that an oxo-Mn V species is responsible for hydrogen-atom abstraction. The observed stereoselectivity results from steric interactions between the bulky porphyrin ligand and the intermediate substrate radical in the halogen rebound step. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Termination of nanoscale zero-valent iron reactivity by addition of bromate as a reducing reactivity competitor

Science.gov (United States)

Mines, Paul D.; Kaarsholm, Kamilla M. S.; Droumpali, Ariadni; Andersen, Henrik R.; Lee, Wontae; Hwang, Yuhoon

2017-09-01

Remediation of contaminated groundwater by nanoscale zero-valent iron (nZVI) is widely becoming a leading environmentally friendly solution throughout the globe. Since a wide range of various nZVI-containing materials have been developed for effective remediation, it is necessary to determine an appropriate way to terminate the reactivity of any nZVI-containing material for a practical experimental procedure. In this study, bimetallic Ni/Fe-NPs were prepared to enhance overall reduction kinetics owing to the catalytic reactivity of nickel on the surface of nZVI. We have tested several chemical strategies in order to terminate nZVI reactivity without altering the concentration of volatile compounds in the solution. The strategies include surface passivation in alkaline conditions by addition of carbonate, and consumption of nZVI by a reaction competitor. Four halogenated chemicals, trichloroethylene, 1,1,1-trichloroethane, atrazine, and 4-chlorophenol, were selected and tested as model groundwater contaminants. Addition of carbonate to passivate the nZVI surface was not effective for trichloroethylene. Nitrate and then bromate were applied to competitively consume nZVI by their faster reduction kinetics. Bromate proved to be more effective than nitrate, subsequently terminating nZVI reactivity for all four of the tested halogenated compounds. Furthermore, the suggested termination method using bromate was successfully applied to obtain trichloroethylene reduction kinetics. Herein, we report the simple and effective method to terminate the reactivity of nZVI by addition of a reducing reactivity competitor.

Influence of Halogen Substituents on the Catalytic Oxidation of 2,4,6-Halogenated Phenols by Fe(III-Tetrakis(p-hydroxyphenyl porphyrins and Potassium Monopersulfate

Directory of Open Access Journals (Sweden)

Seiya Nagao

2011-12-01

Full Text Available The influence of halogen substituents on the catalytic oxidation of 2,4,6-trihalogenated phenols (TrXPs by iron(III-porphyrin/KHSO5 catalytic systems was investigated. Iron(III-5,10,15,20-tetrakis(p-hydroxyphenylporphyrin (FeTHP and its supported variants were employed, where the supported catalysts were synthesized by introducing FeTHP into hydroquinone-derived humic acids via formaldehyde poly-condensation. F (TrFP, Cl (TrCP, Br (TrBP and I (TrIP were examined as halogen substituents for TrXPs. Although the supported catalysts significantly enhanced the degradation and dehalogenation of TrFP and TrCP, the oxidation of TrBP and TrIP was not enhanced, compared to the FeTHP catalytic system. These results indicate that the degree of oxidation of TrXPs is strongly dependent on the types of halogen substituent. The order of dehalogenation levels for halogen substituents in TrXPs was F > Cl > Br > I, consistent with their order of electronegativity. The electronegativity of a halogen substituent affects the nucleophilicity of the carbon to which it is attached. The levels of oxidation products in the reaction mixtures were analyzed by GC/MS after extraction with n-hexane. The most abundant dimer product from TrFP via 2,6-difluoroquinone is consistent with a scenario where TrXP, with a more electronegative halogen substituent, is readily oxidized, while less electronegative halogen substituents are oxidized less readily by iron(III-porphyrin/KHSO5 catalytic systems.

40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal salt of halogenated... Specific Chemical Substances § 721.5452 Alkali metal salt of halogenated organoborate (generic). (a... generically as alkali metal salt of halogenated organoborate (PMN P-00-0638) is subject to reporting under...

Construction of Tungsten Halogen, Pulsed LED, and Combined Tungsten Halogen-LED Solar Simulators for Solar Cell I-V Characterization and Electrical Parameters Determination

Directory of Open Access Journals (Sweden)

Anon Namin

2012-01-01

Full Text Available I-V characterization of solar cells is generally done under natural sunlight or solar simulators operating in either a continuous mode or a pulse mode. Simulators are classified on three features of irradiance, namely, spectral match with respect to air mass 1.5, spatial uniformity, and temporal stability. Commercial solar simulators use Xenon lamps and halogen lamps, whereas LED-based solar simulators are being developed. In this work, we build and test seven simulators for solar cell characterization, namely, one tungsten halogen simulator, four monochromatic (red, green, blue, and white LED simulators, one multicolor LED simulator, and one tungsten halogen-blue LED simulator. The seven simulators provide testing at nonstandard test condition. High irradiance from simulators is obtained by employing elevated supply voltage to tungsten halogen lamps and high pulsing voltages to LEDs. This new approach leads to higher irradiance not previously obtained from tungsten halogen lamps and LEDs. From I-V curves, electrical parameters of solar cell are made and corrected based on methods recommended in the IEC 60891 Standards. Corrected values obtained from non-STC measurements are in good agreement with those obtained from Class AAA solar simulator.

SYNTHESIS AND CHARACTERIZATION OF NEW HALOGENATED CURCUMINOIDS

Directory of Open Access Journals (Sweden)

Eugenio Torres

2013-12-01

Full Text Available In this work a novel procedure of synthesis of compounds analogues to curcumin with halogens atoms in its structure is described, which can increase its solubility and biological activity. Four halogenated curcuminoids were obtained with great pharmacological interest, none of them reported in literature before. Synthesis was carried out by means of the aldol condensation assisted by microwaves of halogenated aromatic aldehydes and acetylacetona, using morpholine as basic catalyst, in absence of solvent, and the reaction just needed 1 min. The products were purified by treatment of the reaction mixture with methanol under ultrasound irradiation, followed by chromatographic column. All obtained compounds were characterized by infrared spectroscopy, nuclear magnetic resonance, quantitative elementary analysis and high resolution mass spectrometry. The RMN-1H data demonstrate in all structures of synthesized curcuminoids the enol form is the most favored.

40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

Science.gov (United States)

2010-07-01

..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject to...

Hydrogen intercalation of single and multiple layer graphene synthesized on Si-terminated SiC(0001) surface

International Nuclear Information System (INIS)

Sołtys, Jakub; Piechota, Jacek; Ptasinska, Maria; Krukowski, Stanisław

2014-01-01

Ab initio density functional theory simulations were used to investigate the influence of hydrogen intercalation on the electronic properties of single and multiple graphene layers deposited on the SiC(0001) surface (Si-face). It is shown that single carbon layer, known as a buffer layer, covalently bound to the SiC substrate, is liberated after hydrogen intercalation, showing characteristic Dirac cones in the band structure. This is in agreement with the results of angle resolved photoelectron spectroscopy measurements of hydrogen intercalation of SiC-graphene samples. In contrast to that hydrogen intercalation has limited impact on the multiple sheet graphene, deposited on Si-terminated SiC surface. The covalently bound buffer layer is liberated attaining its graphene like structure and dispersion relation typical for multilayer graphene. Nevertheless, before and after intercalation, the four layer graphene preserved the following dispersion relations in the vicinity of K point: linear for (AAAA) stacking, direct parabolic for Bernal (ABAB) stacking and “wizard hat” parabolic for rhombohedral (ABCA) stacking

The unique role of halogen substituents in the design of modern agrochemicals.

Science.gov (United States)

Jeschke, Peter

2010-01-01

The past 30 years have witnessed a period of significant expansion in the use of halogenated compounds in the field of agrochemical research and development. The introduction of halogens into active ingredients has become an important concept in the quest for a modern agrochemical with optimal efficacy, environmental safety, user friendliness and economic viability. Outstanding progress has been made, especially in synthetic methods for particular halogen-substituted key intermediates that were previously prohibitively expensive. Interestingly, there has been a rise in the number of commercial products containing 'mixed' halogens, e.g. one or more fluorine, chlorine, bromine or iodine atoms in addition to one or more further halogen atoms. Extrapolation of the current trend indicates that a definite growth is to be expected in fluorine-substituted agrochemicals throughout the twenty-first century. A number of these recently developed agrochemical candidates containing halogen substituents represent novel classes of chemical compounds with new modes of action. However, the complex structure-activity relationships associated with biologically active molecules mean that the introduction of halogens can lead to either an increase or a decrease in the efficacy of a compound, depending on its changed mode of action, physicochemical properties, target interaction or metabolic susceptibility and transformation. In spite of modern design concepts, it is still difficult to predict the sites in a molecule at which halogen substitution will result in optimal desired effects. This review describes comprehensively the successful utilisation of halogens and their unique role in the design of modern agrochemicals, exemplified by various commercial products from Bayer CropScience coming from different agrochemical areas.

Special features of self-compensation of halogen donor action in lead telluride

International Nuclear Information System (INIS)

Kajdanov, V.I.; Nemov, S.A.; Ravich, Yu.I.; Dereza, A.Yu.

1985-01-01

Specific features of self-compensation of halogen donor action in lead telluride are investigasted. Lead telluride samples with chlorine additions (with tellurium excess) and, besides, with bromine- and iodine additions were studied in order to reveal general regularities in alloyind with all halogen donor impurities. Experimental dependences of the difference between the electron and hole concentrations (n-p) in PbTe as a function of an amount of introduced halogen impurities (Ni) are presented for samples with a maximum compensation at 295 K. General features of the n-p=f(Ni) dependence are presented for all halogens. The hypothesis on the kinetic mechanism of increasing the efficiency of self-compensation of halogen donor action in lead telluride is suggested

Spectrographic determination of traces of halogens; Dosage de traces d'halogenes par la methode spectrographique

Energy Technology Data Exchange (ETDEWEB)

Melamed, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

Hollow cathode source is employed for determining traces of halogens (fluorine - chlorine) in the uranium oxide U{sub 3}O{sub 8} qualitatively, detection of at least 40 ppm of fluorine, as alkali fluoride and 125 ppm of chlorine, is possible. (author) [French] Un tube a decharge a cathode creuse a ete utilise pour la determination spectrographique des halogenes (fluor - chlore) presentes a l'etat de traces dans un oxyde d'uranium U{sub 3}O{sub 8}. On a pu deceler qualitativement des teneurs de 40 ppm de fluor sous forme de fluorures alcalins. En ce qui concerne le chlore, la plus faible teneur decelee a ete de 125 ppm. (auteur)

Termination of nanoscale zero-valent iron reactivity by addition of bromate as a reducing reactivity competitor

DEFF Research Database (Denmark)

Mines, Paul D.; Kaarsholm, Kamilla Marie Speht; Droumpali, Ariadni

2017-01-01

, trichloroethylene, 1,1,1-trichloroethane, atrazine, and 4-chlorophenol, were selected and tested as model groundwater contaminants. Addition of carbonate to passivate the nZVI surface was not effective for trichloroethylene. Nitrate and then bromate were applied to competitively consume nZVI by their faster...... reduction kinetics. Bromate proved to be more effective than nitrate, subsequently terminating nZVI reactivity for all four of the tested halogenated compounds. Furthermore, the suggested termination method using bromate was successfully applied to obtain trichloroethylene reduction kinetics. Herein, we...

Halogen-bonded network of trinuclear copper(II 4-iodopyrazolate complexes formed by mutual breakdown of chloroform and nanojars

Directory of Open Access Journals (Sweden)

Stuart A. Surmann

2016-11-01

Full Text Available Crystals of bis(tetrabutylammonium di-μ3-chlorido-tris(μ2-4-iodopyrazolato-κ2N:N′tris[chloridocuprate(II] 1,4-dioxane hemisolvate, (C16H36N2[Cu3(C3H2IN23Cl5]·0.5C4H8O or (Bu4N2[CuII3(μ3-Cl2(μ-4-I-pz3Cl3]·0.5C4H8O, were obtained by evaporating a solution of (Bu4N2[{CuII(μ-OH(μ-4-I-pz}nCO3] (n = 27–31 nanojars in chloroform/1,4-dioxane. The decomposition of chloroform in the presence of oxygen and moisture provides HCl, which leads to the breakdown of nanojars to the title trinuclear copper(II pyrazolate complex, and possibly CuII ions and free 4-iodopyrazole. CuII ions, in turn, act as catalyst for the accelerated decomposition of chloroform, ultimately leading to the complete breakdown of nanojars. The crystal structure presented here provides the first structural description of a trinuclear copper(II pyrazolate complex with iodine-substituted pyrazoles. In contrast to related trinuclear complexes based on differently substituted 4-R-pyrazoles (R = H, Cl, Br, Me, the [Cu3(μ-4-I-pz3Cl3] core in the title complex is nearly planar. This difference is likely a result of the presence of the iodine substituent, which provides a unique, novel feature in copper pyrazolate chemistry. Thus, the iodine atoms form halogen bonds with the terminal chlorido ligands of the surrounding complexes [mean length of I...Cl contacts = 3.48 (1 Å], leading to an extended two-dimensional, halogen-bonded network along (-110. The cavities within this framework are filled by centrosymmetric 1,4-dioxane solvent molecules, which create further bridges via C—H...Cl hydrogen bonds with terminal chlorido ligands of the trinuclear complex not involved in halogen bonding.

Halogenated organic compounds in archived whale oil: A pre-industrial record

International Nuclear Information System (INIS)

Teuten, Emma L.; Reddy, Christopher M.

2007-01-01

To provide additional evidence that several halogenated organic compounds (HOCs) found in environmental samples are natural and not industrially produced, we analyzed an archived whale oil sample collected in 1921 from the last voyage of the whaling ship Charles W. Morgan. This sample, which pre-dates large-scale industrial manufacture of HOCs, contained two methoxylated polybrominated diphenyl ethers (MeO-PBDEs), five halogenated methyl bipyrroles (MBPs), one halogenated dimethyl bipyrrole (DMBP), and tentatively one dimethoxylated polybrominated biphenyl (diMeO-PBB). This result indicates, at least in part, a natural source of the latter compounds. - Nine halogenated organic compounds have been detected in archived whale oil from the early 1920s

Halogenated organic compounds in archived whale oil: A pre-industrial record

Energy Technology Data Exchange (ETDEWEB)

Teuten, Emma L. [Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543 (United States)]. E-mail: emma.teuten@plymouth.ac.uk; Reddy, Christopher M. [Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543 (United States)]. E-mail: creddy@whoi.edu

2007-02-15

To provide additional evidence that several halogenated organic compounds (HOCs) found in environmental samples are natural and not industrially produced, we analyzed an archived whale oil sample collected in 1921 from the last voyage of the whaling ship Charles W. Morgan. This sample, which pre-dates large-scale industrial manufacture of HOCs, contained two methoxylated polybrominated diphenyl ethers (MeO-PBDEs), five halogenated methyl bipyrroles (MBPs), one halogenated dimethyl bipyrrole (DMBP), and tentatively one dimethoxylated polybrominated biphenyl (diMeO-PBB). This result indicates, at least in part, a natural source of the latter compounds. - Nine halogenated organic compounds have been detected in archived whale oil from the early 1920s.

Halogens are key cofactors in building of collagen IV scaffolds outside the cell.

Science.gov (United States)

Brown, Kyle L; Hudson, Billy G; Voziyan, Paul A

2018-05-01

The purpose of this review is to highlight recent advances in understanding the molecular assembly of basement membranes, as exemplified by the glomerular basement membrane (GBM) of the kidney filtration apparatus. In particular, an essential role of halogens in the basement membrane formation has been discovered. Extracellular chloride triggers a molecular switch within non collagenous domains of collagen IV that induces protomer oligomerization and scaffold assembly outside the cell. Moreover, bromide is an essential cofactor in enzymatic cross-linking that reinforces the stability of scaffolds. Halogenation and halogen-induced oxidation of the collagen IV scaffold in disease states damage scaffold function. Halogens play an essential role in the formation of collagen IV scaffolds of basement membranes. Pathogenic damage of these scaffolds by halogenation and halogen-induced oxidation is a potential target for therapeutic interventions.

Halonium Ions as Halogen Bond Donors in the Solid State [XL2]Y Complexes.

Science.gov (United States)

Rissanen, Kari; Haukka, Matti

2015-01-01

The utilization of halogen bonding interactions is one of the most rapidly developing areas of supramolecular chemistry. While the other weak non-covalent interactions and their influence on the structure and chemistry of various molecules, complexes, and materials have been investigated extensively, the understanding, utilizations, and true nature of halogen bonding are still relatively unexplored. Thus its final impact in chemistry in general and in materials science has not yet been fully established. Because of the polarized nature of a Z-X bond (Z=electron-withdrawing atom or moiety and X=halogen atom), such a moiety can act as halogen bond donor when the halogen is polarized enough by the atom/moiety Z. The most studied and utilized halogen bond donor molecules are the perfluorohalocarbons, where Z is a perfluorinated aryl or alkyl moiety and X is either iodine or bromine. Complementing the contemporary halogen bonding research, this chapter reviews the solid state structural chemistry of the most extremely polarized halogen atoms, viz. halonium ions, X+, and discussed them as halogen bond donors in the solid state [XL2]Y complexes (X=halonium ion, Y=any anion).

Inkjet printing the three organic functional layers of two-colored organic light emitting diodes

International Nuclear Information System (INIS)

Coenen, Michiel J.J.; Slaats, Thijs M.W.L.; Eggenhuisen, Tamara M.; Groen, Pim

2015-01-01

Inkjet printing allows for the roll-2-roll fabrication of organic electronic devices at an industrial scale. In this paper we demonstrate the fabrication of two-colored organic light emitting diodes (OLEDs) in which three adjacent organic device layers were inkjet printed from halogen free inks. The resulting devices demonstrate the possibilities offered by this technique for the fabrication of OLEDs for signage and personalized electronics. - Highlights: • Two-colored organic light emitting diodes with 3 inkjet printed device layers were fabricated. • All materials were printed from halogen free inks. • Inkjet printing of emissive materials is suitable for signage applications

Metal-Mediated Halogen Exchange in Aryl and Vinyl Halides: a Review

Science.gov (United States)

Evano, Gwilherm; Nitelet, Antoine; Thilmany, Pierre; Dewez, Damien F.

2018-04-01

Halogenated arenes and alkenes are of prime importance in many areas of science, especially in the pharmaceutical, agrochemical and chemical industries. While the simplest ones are commercially available, some of them are still hardly accessible depending on their substitution patterns and the nature of the halogen atom. Reactions enabling the selective and efficient replacement of the halogen atom of an aryl or alkenyl halide by another one, lighter or heavier, are therefore of major importance since they can be used for example to turn a less reactive aryl/alkenyl chloride into the more reactive iodinated derivatives or, in a reversed sense, to block an undesired reactivity, for late-stage modifications or for the introduction of a radionuclide. If some halogen exchange reactions are possible with activated substrates, they usually require catalysis with metal complexes. Remarkably efficient processes have been developed for metal-mediated halogen exchange in aryl and vinyl halides: they are overviewed, in a comprehensive manner, in this review article.

Halogenated furanones inhibit quorum sensing through accelerated LuxR turnover

DEFF Research Database (Denmark)

Manefield, M.; Rasmussen, Thomas Bovbjerg; Henzter, M.

2002-01-01

fischeri overproduced in Escherichia coli. Whilst a stable interaction between the algal metabolite and the bacterial protein was not found, it was noted by Western analysis that the half-life of the protein is reduced up to 100-fold in the presence of halogenated furanones. This suggests that halogenated...... that the reduction in LuxR concentration is the mechanism by which furanones control expression of AHL-dependent phenotypes. The mode of action by which halogenated furanones reduce cellular concentrations of the LuxR protein remains to be characterized....

Thermal behavior of halogenated imidebismaleimide resins

International Nuclear Information System (INIS)

Mohammad, A.; Al-Halim, N.Z.

1995-01-01

Several new poly-halogenated malecimides, bismaleimides and therir copoly resins were synthessised thermally from their corresponding amic acids. The synthesis was accomplished by two way method (amic acid-polimide) instead of the well-known three way method (amic acid-imide-polyimide). Thermal characterization of monomers and their cured resins was achieved using differential thermal analysis (DTA), dynamic thermogravimetric analysis (TGA) and isothermal gravimetric analysis (IGA). The effect of halogen substituent, especially in the ortho postion, is clear in the imidization proces, while polymerization proceeds almost equally in all systems. Thermal properties of homo and copolymers were correlated with their chemical structures. (author). 15 refs., 4

Development of non-halogen cables for nuclear power stations

Energy Technology Data Exchange (ETDEWEB)

Yagyu, Hideki; Yamamoto, Yasuaki; Onishi, Takao (Hitachi Cable, Ltd., Tokyo (Japan))

1983-12-01

The non-halogen fire-resistant cables for nuclear power stations which never generate halogen gas, have been developed. The cables comprise the insulator of EP rubber and the sheath of polyolefine containing non-halogen inorganic fire-retardant. The results of the environmental test and fire-resistance test are described. In the environmental test, the cables were subjected to the heating, gamma-irradiation and steam exposure successively, according to IEEE specification 323,383, and subsequently the change in the appearance, tensile strength and electrical performance of the cables was measured. In the fire-resistance test, the vertical tray fire test according to the IEEE specification 383 was adopted, and other tests including the vertical fire test on insulator cores, oxygen index, the generation of corrosive gas, copper mirror corrosion test, gas toxicity test and optical smoke density test were carried out. It became clear that the cables did not generate halogen gas on burning, and brought about reduced toxicity, corrosion and smoke, and that the safety against fire is greatly improved by using the cables.

Development of non-halogen cables for nuclear power stations

International Nuclear Information System (INIS)

Yagyu, Hideki; Yamamoto, Yasuaki; Onishi, Takao

1983-01-01

The non-halogen fire-resistant cables for nuclear power stations which never generate halogen gas, have been developed. The cables comprise the insulator of EP rubber and the sheath of polyolefine containing non-halogen inorganic fire-retardant. The results of the environmental test and fire-resistance test are described. In the environmental test, the cables were subjected to the heating, gamma-irradiation and steam exposure successively, according to IEEE specification 323,383, and subsequently the change in the appearance, tensile strength and electrical performance of the cables was measured. In the fire-resistance test, the vertical tray fire test according to the IEEE specification 383 was adopted, and other tests including the vertical fire test on insulator cores, oxygen index, the generation of corrosive gas, copper mirror corrosion test, gas toxicity test and optical smoke density test were carried out. It became clear that the cables did not generate halogen gas on burning, and brought about reduced toxicity, corrosion and smoke, and that the safety against fire is greatly improved by using the cables. (Yoshitake, I.)

Process for reducing halogen impurities in oil products

Energy Technology Data Exchange (ETDEWEB)

Basler, F.

1990-08-14

Oil products, in particular waste oils, may be efficiently reprocessed according to an economic and technically simple method for removing impurities, notably halogens. In this method, the oil product is treated at temperatures up to about 150{degree}C with an effective amount of an aqueous solution of at least one compound selected from the group consisting of a strong acid, a salt of a weak base and a strong acid and precursors thereof. The oil product obtained in this step is treated at increased temperatures with at least one halogen binding agent. The water and/or solids from the product so treated are separated out. The process of the invention can be carried out in a conventional stripping apparatus. The strong acid used in the first step is preferably selected from sulfurous acid, phosphoric acid, phosphorous acid, and phosphonic acid. The salt of the weak base and strong acid is preferably ammonium sulfate, ammonium bisulfate, ammonium sulfite, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphite, and ammonium phosphonic acid. The second step of the method is preferably a coagulation step in which organic halogen compounds break down into hydrogen halides which are neutralized by the added halogen binding agents. The preferred halogen binding agents are ammonia and/or an organic base. The coagulation is preferably carried out in heat exchangers so that the oil is heated in 3 stages and the oil from each stage is passed through a cascade tower. In the third step, additives may be used to enhance separation of the oil. Experiments are described to illustrate the method of the invention. 1 tab.

Participation of the Halogens in Photochemical Reactions in Natural and Treated Waters

Directory of Open Access Journals (Sweden)

Yi Yang

2017-10-01

Full Text Available Halide ions are ubiquitous in natural waters and wastewaters. Halogens play an important and complex role in environmental photochemical processes and in reactions taking place during photochemical water treatment. While inert to solar wavelengths, halides can be converted into radical and non-radical reactive halogen species (RHS by sensitized photolysis and by reactions with secondary reactive oxygen species (ROS produced through sunlight-initiated reactions in water and atmospheric aerosols, such as hydroxyl radical, ozone, and nitrate radical. In photochemical advanced oxidation processes for water treatment, RHS can be generated by UV photolysis and by reactions of halides with hydroxyl radicals, sulfate radicals, ozone, and other ROS. RHS are reactive toward organic compounds, and some reactions lead to incorporation of halogen into byproducts. Recent studies indicate that halides, or the RHS derived from them, affect the concentrations of photogenerated reactive oxygen species (ROS and other reactive species; influence the photobleaching of dissolved natural organic matter (DOM; alter the rates and products of pollutant transformations; lead to covalent incorporation of halogen into small natural molecules, DOM, and pollutants; and give rise to certain halogen oxides of concern as water contaminants. The complex and colorful chemistry of halogen in waters will be summarized in detail and the implications of this chemistry for global biogeochemical cycling of halogen, contaminant fate in natural waters, and water purification technologies will be discussed.

First-principles studies on the effects of halogen adsorption on monolayer antimony.

Science.gov (United States)

Yeoh, Keat Hoe; Yoon, Tiem Leong; Ong, Duu Sheng; Lim, Thong Leng; Zuntu Abdullahi, Yusuf

2017-09-27

Using first-principles calculations, we carry out systematic studies on the electronic, magnetic and structural properties of halogenated β-phase antimonene. We consider two different levels of halogen adatom coverage i.e. Θ = 1/8 and Θ = 1/18. It is found that F, Cl and Br adatoms act as acceptors whereas the I adatom acts as a donor. For a high coverage of Θ = 1/8, halogenated β-phase antimonene exhibits metallic characteristics. With a lower coverage of Θ = 1/18, through the adsorption of F, Cl and Br the semiconducting unstrained antimonene becomes metallic. In contrast, I-adsorbed antimonene remains semiconducting but exhibits magnetic behavior. We further investigate the effects of bi-axial strain on the halogenated β-phase antimonene. It is found that bi-axial strain can only induce ferromagnetism on the halogenated antimonene at Θ = 1/18. However, the ferromagnetism is suppressed when the applied strain is high. We uncover that the emergence of strain-dependent magnetism is attributed to the presence of localized states in the bandgap resulting from collective effects of bi-axial strain and the adsorption of halogen atoms.

Halogenation dictates the architecture of amyloid peptide nanostructures.

Science.gov (United States)

Pizzi, Andrea; Pigliacelli, Claudia; Gori, Alessandro; Nonappa; Ikkala, Olli; Demitri, Nicola; Terraneo, Giancarlo; Castelletto, Valeria; Hamley, Ian W; Baldelli Bombelli, Francesca; Metrangolo, Pierangelo

2017-07-20

Amyloid peptides yield a plethora of interesting nanostructures though difficult to control. Here we report that depending on the number, position, and nature of the halogen atoms introduced into either one or both phenylalanine benzene rings of the amyloid β peptide-derived core-sequence KLVFF, four different architectures were obtained in a controlled manner. Our findings demonstrate that halogenation may develop as a general strategy to engineer amyloidal peptide self-assembly and obtain new amyloidal nanostructures.

Induction of bacterial antibiotic resistance by mutagenic halogenated nitrogenous disinfection byproducts

International Nuclear Information System (INIS)

Lv, Lu; Yu, Xin; Xu, Qian; Ye, Chengsong

2015-01-01

Halogenated nitrogenous disinfection byproducts (N-DBPs) raise concerns regarding their mutagenicity and carcinogenicity threatening public health. However, environmental consequence of their mutagenicity has received less attention. In this study, the effect of halogenated N-DBPs on bacterial antibiotic resistance (BAR) was investigated. After exposure to bromoacetamide (BAcAm), trichloroacetonitrile (TCAN) or tribromonitromethane (TBNM), the resistance of Pseudomonas aeruginosa PAO1 to both individual and multiple antibiotics (ciprofloxacin, gentamicin, polymyxin B, rifampin, tetracycline, ciprofloxacin + gentamicin and ciprofloxacin + tetracycline) was increased, which was predominantly ascribed to the overexpression of efflux pumps. The mechanism of this effect was demonstrated to be mutagenesis through sequencing and analyzing antibiotic resistance genes. The same induction phenomena also appeared in Escherichia coli, suggesting this effect may be universal to waterborne pathogens. Therefore, more attention should be given to halogenated N-DBPs, as they could increase not only genotoxicological risks but also epidemiological risks of drinking water. - Highlights: • The halogenated N-DBPs could induce bacterial antibiotic resistance. • Both individual and multiple resistances could be induced. • Efflux mechanism played an important role in the induced antibiotic resistance. • The halogenated N-DBPs induced bacterial antibiotic resistance via mutagenesis. • Effects of N-DBPs on antibiotic resistance may be universal to waterborne pathogens. - Halogenated N-DBPs could increase antibiotic resistance, even multidrug resistance via mutagenesis, contributing to the enrichment of antibiotic resistant bacteria in drinking water

Concentration-dependent multiple chirality transition in halogen-bond-driven 2D self-assembly process

Science.gov (United States)

Miao, Xinrui; Li, Jinxing; Zha, Bao; Miao, Kai; Dong, Meiqiu; Wu, Juntian; Deng, Wenli

2018-03-01

The concentration-dependent self-assembly of iodine substituted thienophenanthrene derivative (5,10-DITD) is investigated at the 1-octanic acid/graphite interface using scanning tunneling microscopy. Three kinds of chiral arrangement and transition of 2D molecular assembly mainly driven by halogen bonding is clearly revealed. At high concentration the molecules self-assembled into a honeycomb-like chiral network. Except for the interchain van der Waals forces, this pattern is stabilized by intermolecular continuous Cdbnd O⋯I⋯S halogen bonds in each zigzag line. At moderate concentration, a chiral kite-like nanoarchitecture are observed, in which the Cdbnd O⋯I⋯S and I⋯Odbnd C halogen bonds, along with the molecule-solvent Cdbnd O⋯I⋯H halogen bonds are the dominated forces to determine the structural formation. At low concentration, the molecules form a chiral cyclic network resulting from the solvent coadsorption mainly by molecule-molecule Cdbnd O⋯I⋯S halogen bonds and molecule-solvent Cdbnd O⋯I⋯H halogen bonds. The density of molecular packing becomes lower with the decreasing of the solution concentration. The solution-concentration dependent self-assembly of thienophenanthrene derivative with iodine and ester chain moieties reveals that the type of intermolecular halogen bond and the number of the co-adsorbing 1-octanic acids by molecule-solvent Cdbnd O⋯I⋯H halogen bonds determine the formation and transformation of chirality. This research emphasizes the role of different types of halogen (I) bonds in the controllable supramolecular structures and provides an approach for the fabrication of chirality.

LNG TERMINAL SAFE OPERATION MANAGEMENT

OpenAIRE

Andrzej ADAMKIEWICZ; Włodzimierz KAMIŃSKI

2012-01-01

This article presents the significance of LNG terminal safety issues in natural gas sea transport. It shows particular requirements for LNG transmission installations resulting from the specific properties of LNG. Out of the multi‐layer critical safety areas comprising structural elements of the terminal safety system, possibilities to decrease the risk of emergency occurrence on LNG terminals have been selected. Tasks performed by the LNG terminal, together with its own personnel and the out...

Layer by layer assembly of catalase and amine-terminated ionic liquid onto titanium nitride nanoparticles modified glassy carbon electrode: Study of direct voltammetry and bioelectrocatalytic activity

International Nuclear Information System (INIS)

Saadati, Shagayegh; Salimi, Abdollah; Hallaj, Rahman; Rostami, Amin

2012-01-01

Highlights: ► Catalase and amine-terminated ionic liquid were immobilized to GC/TiNnp with LBL assembly method. ► First a thin layer of NH 2 -IL is covalently attached to GC/TiNnp electrode using electro-oxidation. ► With alternative assemble of IL and catalase with positive and negative charged, multilayer was formed. ► Immobilized catalase shows excellent electrocatalytic activity toward H 2 O 2 reduction. ► Biosensor response is directly correlated to the number of bilayers. - Abstract: A novel, simple and facile layer by layer (LBL) approach is used for modification of glassy carbon (GC) electrode with multilayer of catalase and nanocomposite containing 1-(3-Aminopropyl)-3-methylimidazolium bromide (amine terminated ionic liquid (NH 2 -IL)) and titanium nitride nanoparticles (TiNnp). First a thin layer of NH 2 -IL is covalently attached to GC/TiNnp electrode using electro-oxidation method. Then, with alternative self assemble positively charged NH 2 -IL and negatively charged catalase a sensitive H 2 O 2 biosensor is constructed, whose response is directly correlated to the number of bilayers. The surface coverage of active catalase per bilayer, heterogeneous electron transfer rate constant (k s ) and Michaelis–Menten constant (K M ) of immobilized catalase were 3.32 × 10 −12 mol cm −2 , 5.28 s −1 and 1.1 mM, respectively. The biosensor shows good stability, high reproducibility, long life-time, and fast amperometric response with the high sensitivity of 380 μA mM −1 cm −2 and low detection limit of 100 nM at concentration range up to 2.1 mM.

A nitride-based epitaxial surface layer formed by ammonia treatment of silicene-terminated ZrB{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Wiggers, F. B., E-mail: F.B.Wiggers@utwente.nl; Van Bui, H.; Schmitz, J.; Kovalgin, A. Y.; Jong, M. P. de [MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede (Netherlands); Friedlein, R.; Yamada-Takamura, Y. [School of Materials Science, Japan Advanced Institute of Science and Technology, Nomi, Ishikawa 923-1292 (Japan)

2016-04-07

We present a method for the formation of an epitaxial  surface layer involving B, N, and Si atoms on a ZrB{sub 2}(0001) thin film on Si(111). It has the potential to be an insulating growth template for 2D semiconductors. The chemical reaction of NH{sub 3} molecules with the silicene-terminated ZrB{sub 2}  surface was characterized by synchrotron-based, high-resolution core-level photoelectron spectroscopy and low-energy electron diffraction. In particular, the dissociative chemisorption of NH{sub 3} at 400 °C leads to surface  nitridation, and subsequent annealing up to 830 °C results in a solid phase reaction with the ZrB{sub 2} subsurface layers. In this way, a new nitride-based epitaxial  surface layer is formed with hexagonal symmetry and a single in-plane crystal orientation.

LNG TERMINAL SAFE OPERATION MANAGEMENT

Directory of Open Access Journals (Sweden)

Andrzej ADAMKIEWICZ

2012-07-01

Full Text Available This article presents the significance of LNG terminal safety issues in natural gas sea transport. It shows particular requirements for LNG transmission installations resulting from the specific properties of LNG. Out of the multi‐layer critical safety areas comprising structural elements of the terminal safety system, possibilities to decrease the risk of emergency occurrence on LNG terminals have been selected. Tasks performed by the LNG terminal, together with its own personnel and the outside one, have been defined. General theses for LNG terminal safety have been formulated.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Ultraviolet radiation and blue-light emissions from spotlights incorporating tungsten halogen lamps

CERN Document Server

MacKinlay, Alistair F; Whillock, M J

1989-01-01

This report summarises measurements of the ultraviolet radiation and blue-light emissions from eleven 'desk-top' tungsten halogen (quartz) lamps and one 'floor-standing' tungsten halogen (quartz) lamp available in the UK. Values of occupational hazard weighted and erythemally weighted ultraviolet radiation irradiance and measurements and relevant calculations of blue-light hazards are presented. It is concluded that the safety design of some desk-top tungsten halogen lamps is inadequate to prevent unnecessary exposure of the skin to potentially harmful ultraviolet radiation. It is recommended that all tungsten halogen lamps should have sufficient filtration to reduce their ultraviolet emissions to an acceptably low level. As long as the comfort aversion responses of the eye are respected, direct viewing of the lamps examined should not constitute a retinal hazard.

Ultraviolet radiation and blue-light emissions from spotlights incorporating tungsten halogen lamps

International Nuclear Information System (INIS)

McKinlay, A.F.; Whillock, M.J.; Meulemans, C.C.E.

1989-07-01

This report summarises measurements of the ultraviolet radiation and blue-light emissions from eleven 'desk-top' tungsten halogen (quartz) lamps and one 'floor-standing' tungsten halogen (quartz) lamp available in the UK. Values of occupational hazard weighted and erythemally weighted ultraviolet radiation irradiance and measurements and relevant calculations of blue-light hazards are presented. It is concluded that the safety design of some desk-top tungsten halogen lamps is inadequate to prevent unnecessary exposure of the skin to potentially harmful ultraviolet radiation. It is recommended that all tungsten halogen lamps should have sufficient filtration to reduce their ultraviolet emissions to an acceptably low level. As long as the comfort aversion responses of the eye are respected, direct viewing of the lamps examined should not constitute a retinal hazard. (author)

Determination of halogens by flame emission of metal halogenides

International Nuclear Information System (INIS)

Henrion, G.; Marquardt, D.; Stoecker, B.

1979-01-01

The A-B systems InF, InCl, InBr, and InI have been excited by laminar H 2 -N 2 flames in order to dermine individual halogens or their mixtures qualitatively or quantitatively. In optimizing the fuel gas composition two different behavior patterns have been found for band intensities, which are correlated with binding energies of InX (X = halogen). The low temperature of the flame leads to complicated matrix effects which first of all result from effects on excitation and from competitive reactions. In general, cations cause a decreased intensity. Therefore, salts have to be converted into hydrohalide acids by ion exchange. Qualitative determinations of individual halogens are possible at a 500 to 50,000fold excess of the others, whereas quantitative determinations can be performed at a 100 to 5,000fold excess in 10 -4 molar solutions with errors of 2 to 10 per cent. (author)

Halogen systematics in the Mallik 5L-38 gas hydrate production research well, Northwest Territories, Canada: Implications for the origin of gas hydrates under terrestrial permafrost conditions

International Nuclear Information System (INIS)

Tomaru, Hitoshi; Fehn, Udo; Lu, Zunli; Matsumoto, Ryo

2007-01-01

The authors report here halogen concentrations in pore waters and sediments collected from the Mallik 5L-38 gas hydrate production research well, a permafrost location in the Mackenzie Delta, Northwest Territories, Canada. Iodine and Br are commonly enriched in waters associated with CH 4 , reflecting the close association between these halogens and source organic materials. Pore waters collected from the Mallik well show I enrichment, by one order of magnitude above that of seawater, particularly in sandy layers below the gas hydrate stability zone (GHSZ). Although Cl and Br concentrations increase with depth similar to the I profile, they remain below seawater values. The increase in I concentrations observed below the GHSZ suggests that I-rich fluids responsible for the accumulation of CH 4 in gas hydrates are preferentially transported through the sandy permeable layers below the GHSZ. The Br and I concentrations and I/Br ratios in Mallik are considerably lower than those in marine gas hydrate locations, demonstrating a terrestrial nature for the organic materials responsible for the CH 4 at the Mallik site. Halogen systematics in Mallik suggest that they are the result of mixing between seawater, freshwater and an I-rich source fluid. The comparison between I/Br ratios in pore waters and sediments speaks against the origin of the source fluids within the host formations of gas hydrates, a finding compatible with the results from a limited set of 129 I/I ratios determined in pore waters, which gives a minimum age of 29 Ma for the source material, i.e. at the lower end of the age range of the host formations. The likely scenario for the gas hydrate formation in Mallik is the derivation of CH 4 together with I from the terrestrial source materials in formations other than the host layers through sandy permeable layers into the present gas hydrate zones

High-temperature peaks of thermostimulated luminescence in the ammonium halogens

International Nuclear Information System (INIS)

Kim, L.M.; Musenova, Eh.K.; Mukhamedrakhimov, K.U.

2003-01-01

The ammonium halogen crystals (AHC) are the close analogs of the alkali halogen crystals by the type of chemical bonds and crystal lattice structure. The ammonium halogen after irradiation by X-rays within 80-300 K range have two peaks of thermo-stimulation luminescence. Its maximums in dependence of anions type are in the 110-120 K and 170-180 K ranges. The first range is related with activation of auto-localized holes migration, and the second one - with the NH 3 + defects decay. Experimentally is established, that the pure ammonium halogens have memory about the previous irradiation at heating up to 300 K. After repeat irradiation the recombination luminescence high-temperature peak's shoulder is appearing. The second luminescence peak's shoulder revealing does not depend on the impurity center nature. It is known, that in the AHC there is the next thermo-stimulation luminescence peak within 340-360 K. The thermal annealing of this peak leads to the memory effect disappearance. So, the observing phenomenon is related with own defect of the matrix in the cation sublattice. Experimentally is established, that at a room temperature the AHC memorizing about previous irradiation during 20 h

Retention efficiencies of halogenated and non-halogenated hydrocarbons in selected wetland ecosystem in Lake Victoria Basin

Directory of Open Access Journals (Sweden)

Shadrack Mule

2015-06-01

Full Text Available The determination of retention efficiencies of halogenated and non-halogenated hydrocarbon in selected wetland ecosystems in Lake Victoria basin was carried out. Qualitative and quantitative determination of the presence of residual hydrocarbons in Kigwal/Kimondi, Nyando and Nzoia wetland ecosystems using Gas Chromatography - Mass Spectrometer (GC-MS instrument indicated the presence of residual organochlorines, organophosphorus, carbamates and synthetic pyrethroid hydrocarbons in water, sediment and plant materials. In order to compare the retention efficiencies of the wetlands, the wetland ecosystems were divided into three different sections, namely: inlet, mid and outlet. Calculations of mass balances of residual halogenated and non-halogenated hydrocarbons at the respective sections was done taking into account the partition of the studied compounds in samples of water, sediments and papyrus reed plant materials and analyzed using validated Gas Chromatography - Mass Spectrometer (GC-MS method. From the analysis, several residual hydrocarbons namely: bendiocarb, benzene hexachloride (BHC, carbaryl, cypermethrin, decis, deltamethrin, diazinon, dieldrin, DDT, DDD, DDE, malathion, propoxur, sumithion, 5-phenylrhodanine, 1,3,5-trichlorobenzene, 1-(2-phenoxybenzylhydrazine were detected and quantified. The levels of the selected residual hydrocarbons in water samples were used to calculate the retention efficiencies of a specific hydrocarbon and the values recorded. Generally, River Nyando wetland recorded mean percentage retention efficiencies of 76 and 94% for dry and rainy seasons respectively; Kigwal/Kimondi wetland had seasonal mean percentage retention efficiencies of 63 to 78%. River Nzoia also had calculated seasonal mean percentage retention efficiencies of between 56 to 88%. Dry season had lower mean percentages retention efficiencies as compared to rainy season in the three wetlands of interest during the period of study. The study

Halogens determination in vegetable NBS standard reference materials

International Nuclear Information System (INIS)

Stella, R.; Genova, N.; Di Casa, M.

1977-01-01

Levels of all four halogens in Orchard Leaves, Pine Needles and Tomato Leaves NBS reference standards were determined. For fluorine a spiking isotope dilution method was used followed by HF absorption on glass beads. Instrumental nuclear activation analysis was adopted for chlorine and bromine determination. Radiochemical separation by a distillation procedure was necessary for iodine nuclear activation analysis after irradiation. Activation parameters of Cl, Br and I are reported. Results of five determinations for each halogen in Orchard Leaves, Pine Needles and Tomato Leaves NBS Standard Materials and Standard deviations of the mean are reported. (T.I.)

Layer by layer assembly of catalase and amine-terminated ionic liquid onto titanium nitride nanoparticles modified glassy carbon electrode: Study of direct voltammetry and bioelectrocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Saadati, Shagayegh [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Salimi, Abdollah, E-mail: absalimi@uok.ac.ir [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Hallaj, Rahman; Rostami, Amin [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)

2012-11-13

Highlights: Black-Right-Pointing-Pointer Catalase and amine-terminated ionic liquid were immobilized to GC/TiNnp with LBL assembly method. Black-Right-Pointing-Pointer First a thin layer of NH{sub 2}-IL is covalently attached to GC/TiNnp electrode using electro-oxidation. Black-Right-Pointing-Pointer With alternative assemble of IL and catalase with positive and negative charged, multilayer was formed. Black-Right-Pointing-Pointer Immobilized catalase shows excellent electrocatalytic activity toward H{sub 2}O{sub 2} reduction. Black-Right-Pointing-Pointer Biosensor response is directly correlated to the number of bilayers. - Abstract: A novel, simple and facile layer by layer (LBL) approach is used for modification of glassy carbon (GC) electrode with multilayer of catalase and nanocomposite containing 1-(3-Aminopropyl)-3-methylimidazolium bromide (amine terminated ionic liquid (NH{sub 2}-IL)) and titanium nitride nanoparticles (TiNnp). First a thin layer of NH{sub 2}-IL is covalently attached to GC/TiNnp electrode using electro-oxidation method. Then, with alternative self assemble positively charged NH{sub 2}-IL and negatively charged catalase a sensitive H{sub 2}O{sub 2} biosensor is constructed, whose response is directly correlated to the number of bilayers. The surface coverage of active catalase per bilayer, heterogeneous electron transfer rate constant (k{sub s}) and Michaelis-Menten constant (K{sub M}) of immobilized catalase were 3.32 Multiplication-Sign 10{sup -12} mol cm{sup -2}, 5.28 s{sup -1} and 1.1 mM, respectively. The biosensor shows good stability, high reproducibility, long life-time, and fast amperometric response with the high sensitivity of 380 {mu}A mM{sup -1} cm{sup -2} and low detection limit of 100 nM at concentration range up to 2.1 mM.

Gas phase acid, ammonia and aerosol ionic and trace element concentrations at Cape Verde during the Reactive Halogens in the Marine Boundary Layer (RHaMBLe) 2007 intensive sampling period

Science.gov (United States)

Sander, R.; Pszenny, A. A. P.; Keene, W. C.; Crete, E.; Deegan, B.; Long, M. S.; Maben, J. R.; Young, A. H.

2013-12-01

We report mixing ratios of soluble reactive trace gases sampled with mist chambers and the chemical composition of bulk aerosol and volatile inorganic bromine (Brg) sampled with filter packs during the Reactive Halogens in the Marine Boundary Layer (RHaMBLe) field campaign at the Cape Verde Atmospheric Observatory (CVAO) on São Vicente island in the tropical North Atlantic in May and June 2007. The gas-phase data include HCl, HNO3, HONO, HCOOH, CH3COOH, NH3, and volatile reactive chlorine other than HCl (Cl*). Aerosol samples were analyzed by neutron activation (Na, Al, Cl, V, Mn, and Br) and ion chromatography (SO42-, Cl-, Br-, NH4+, Na+, K+, Mg2+, and Ca2+). Content and quality of the data, which are available under doi:10.5281/zenodo.6956, are presented and discussed.

Gas phase acid, ammonia and aerosol ionic and trace element concentrations at Cape Verde during the Reactive Halogens in the Marine Boundary Layer (RHaMBLe 2007 intensive sampling period

Directory of Open Access Journals (Sweden)

R. Sander

2013-12-01

Full Text Available We report mixing ratios of soluble reactive trace gases sampled with mist chambers and the chemical composition of bulk aerosol and volatile inorganic bromine (Brg sampled with filter packs during the Reactive Halogens in the Marine Boundary Layer (RHaMBLe field campaign at the Cape Verde Atmospheric Observatory (CVAO on São Vicente island in the tropical North Atlantic in May and June 2007. The gas-phase data include HCl, HNO3, HONO, HCOOH, CH3COOH, NH3, and volatile reactive chlorine other than HCl (Cl*. Aerosol samples were analyzed by neutron activation (Na, Al, Cl, V, Mn, and Br and ion chromatography (SO42−, Cl−, Br−, NH4+, Na+, K+, Mg2+, and Ca2+. Content and quality of the data, which are available under doi:10.5281/zenodo.6956, are presented and discussed.

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

Directory of Open Access Journals (Sweden)

Janet E. Del Bene

2017-11-01

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

A Survey of Electron Impact Cross-Sections for Halogens and Halogen Compounds of Interest to Plasma Processing

Science.gov (United States)

Sharma, S. P.; Rao, M. V. V. S.; Arnold, James O. (Technical Monitor)

1998-01-01

Published electron impact cross section data on halogens Cl2, F2, and halogen containing compounds such as Cx Fy, HCl, Cx Cly Fz are reviewed and critically evaluated based on the information provided by various researchers. The present work reports data on electron impact excitation, ionization, dissociation, electron attachment, electron detachment, and photo detachment. Elastic scattering cross sections and data on bulk properties such as diffusion coefficients in various background gases are also evaluated. Since some of the cross sectional data is derived from indirect measurements such as drift velocity, care has been taken to reconcile the differences among the reported data with due attention to the measurement technique. In conclusion, the processes with no or very limited amount of data and questionable set of data are identified and recommendation for further research direction is made.

Estrogenicity of halogenated bisphenol A: in vitro and in silico investigations.

Science.gov (United States)

Zhang, Jie; Li, Tiezhu; Wang, Tuoyi; Yuan, Cuiping; Zhong, Shuning; Guan, Tianzhu; Li, Zhuolin; Wang, Yongzhi; Yu, Hansong; Luo, Quan; Wang, Yongjun; Zhang, Tiehua

2018-03-01

The binding interactions of bisphenol A (BPA) and its halogenated derivatives (halogenated BPAs) to human estrogen receptor α ligand binding domain (hERα-LBD) was investigated using a combined in vitro and in silico approach. First, the recombinant hERα-LBD was prepared as a soluble protein in Escherichia coli BL21(DE3)pLysS. A native fluorescent phytoestrogen, coumestrol, was employed as tracer for the fluorescence polarization assay. The results of the in vitro binding assay showed that bisphenol compounds could bind to hERα-LBD as the affinity ligands. All the tested halogenated BPAs exhibited weaker receptor binding than BPA, which might be explained by the steric effect of substituents. Molecular docking studies elucidated that the halogenated BPAs adopted different conformations in the flexible hydrophobic ligand binding pocket (LBP), which is mainly dependent on their distinct halogenation patterns. The compounds with halogen substituents on the phenolic rings and on the bridging alkyl moiety acted as agonists and antagonists for hERα, respectively. Interestingly, all the compounds in the agonist conformation of hERα formed a hydrogen bond with His524, while the compounds in the antagonist conformation formed a hydrogen bond with Thr347. These docking results suggested a pivotal role of His524/Thr347 in maintaining the hERα structure in the biologically active agonist/antagonist conformation. Comparison of the calculated binding energies vs. experimental binding affinities yielded a good correlation, which might be applicable for the structure-based design of novel bisphenol compounds with reduced toxicities and for environmental risk assessment. In addition, based on hERα-LBD as a recognition element, the proposed fluorescence polarization assay may offer an alternative to chromatographic techniques for the multi-residue determination of bisphenol compounds.

Halogen degassing during ascent and eruption of water-poor basaltic magma

Science.gov (United States)

Edmonds, M.; Gerlach, T.M.; Herd, Richard A.

2009-01-01

A study of volcanic gas composition and matrix glass volatile concentrations has allowed a model for halogen degassing to be formulated for K??lauea Volcano, Hawai'i. Volcanic gases emitted during 2004-2005 were characterised by a molar SO2/HCl of 10-64, with a mean of 33; and a molar HF/HCl of 0-5, with a mean of 1.0 (from approximately 2500 measurements). The HF/HCl ratio was more variable than the SO2/HCl ratio, and the two correlate weakly. Variations in ratio took place over rapid timescales (seconds). Matrix glasses of Pele's tears erupted in 2006 have a mean S, Cl and F content of 67, 85 and 173??ppm respectively, but are associated with a large range in S/F. A model is developed that describes the open system degassing of halogens from parental magmas, using the glass data from this study, previously published results and parameterisation of sulphur degassing from previous work. The results illustrate that halogen degassing takes place at pressures of < 1??MPa, equivalent to < ~ 35??m in the conduit. Fluid-melt partition coefficients for Cl and F are low (< 1.5); F only degasses appreciably at < 0.1??MPa above atmospheric pressure, virtually at the top of the magma column. This model reproduces the volcanic gas data and other observations of volcanic activity well and is consistent with other studies of halogen degassing from basaltic magmas. The model suggests that variation in volcanic gas halogen ratios is caused by exsolution and gas-melt separation at low pressures in the conduit. There is no evidence that either diffusive fractionation or near-vent chemical reactions involving halogens is important in the system, although these processes cannot be ruled out. The fluxes of HCl and HF from K??lauea during 2004-5 were ~ 25 and 12??t/d respectively. ?? 2008 Elsevier B.V.

Process for removing halogenated aliphatic and aromatic compounds from petroleum products

Science.gov (United States)

Googin, J.M.; Napier, J.M.; Travaglini, M.A.

1983-09-20

A process is described for removing halogenated aliphatic and aromatic compounds, e.g., polychlorinated biphenyls, from petroleum products by solvent extraction. The halogenated aliphatic and aromatic compounds are extracted from a petroleum product into a polar solvent by contacting the petroleum product with the polar solvent. The polar solvent is characterized by a high solubility for the extracted halogenated aliphatic and aromatic compounds, a low solubility for the petroleum product and considerable solvent power for polyhydroxy compound. The preferred polar solvent is dimethylformamide. A miscible compound, such as, water or a polyhydroxy compound, is added to the polar extraction solvent to increase the polarity of the polar extraction solvent. The halogenated aliphatic and aromatic compounds are extracted from the highly-polarized mixture of water or polyhydroxy compound and polar extraction solvent into a low polar or nonpolar solvent by contacting the water or polyhydroxy compound-polar solvent mixture with the low polar or nonpolar solvent. The halogenated aliphatic and aromatic compounds and the low polar or nonpolar solvent are separated by physical means, e.g., vacuum evaporation. The polar and nonpolar solvents are recovered from recycling. The process can easily be designed for continuous operation. Advantages of the process include that the polar solvent and a major portion of the nonpolar solvent can be recycled, the petroleum products are reclaimable and the cost for disposing of waste containing polychlorinated biphenyls is significantly reduced. 1 fig.

Iodine-mediated coastal particle formation: an overview of the Reactive Halogens in the Marine Boundary Layer (RHaMBLe Roscoff coastal study

Directory of Open Access Journals (Sweden)

G. McFiggans

2010-03-01

Full Text Available This paper presents a summary of the measurements made during the heavily-instrumented Reactive Halogens in the Marine Boundary Layer (RHaMBLe coastal study in Roscoff on the North West coast of France throughout September 2006. It was clearly demonstrated that iodine-mediated coastal particle formation occurs, driven by daytime low tide emission of molecular iodine, I₂, by macroalgal species fully or partially exposed by the receding waterline. Ultrafine particle concentrations strongly correlate with the rapidly recycled reactive iodine species, IO, produced at high concentrations following photolysis of I₂. The heterogeneous macroalgal I₂ sources lead to variable relative concentrations of iodine species observed by path-integrated and in situ measurement techniques.

Apparent particle emission fluxes were associated with an enhanced apparent depositional flux of ozone, consistent with both a direct O₃ deposition to macroalgae and involvement of O₃ in iodine photochemistry and subsequent particle formation below the measurement height. The magnitude of the particle formation events was observed to be greatest at the lowest tides with the highest concentrations of ultrafine particles growing to the largest sizes, probably by the condensation of anthropogenically-formed condensable material. At such sizes the particles should be able to act as cloud condensation nuclei at reasonable atmospheric supersaturations.

Risk assessment for halogenated solvents

International Nuclear Information System (INIS)

Travis, C.C.

1988-01-01

A recent development in the cancer risk area is the advent of biologically based pharmacokinetic and pharmacodynamic models. These models allow for the incorporation of biological and mechanistic data into the risk assessment process. These advances will not only improve the risk assessment process for halogenated solvents but will stimulate and guide basic research in the biological area

Development of halogen-free cables for nuclear power plants

International Nuclear Information System (INIS)

Yamamoto, Mitsuo; Ito, Kazumi; Yaji, Takeo; Yoshida, Shin; Sakurai, Takako; Matsushita, Shigetoshi.

1990-01-01

On the occasion where serious fire accidents were experienced in the past, the need for making flame-retardant wire and cable incombustible took place and has since been generalizing. Various sorts of flame-retardant cables have already been developed and been actually used. From the viewpoint of avoiding the interference with the evacuation and fire-fighting activity in case of fire or the secondary accidents such as corrosion of the distributing panel, etc., the demand for non-halogen flame-retardant cable has rapidly been increasing in recent years in some fields of general industries, because this specific cable would generate the least amount of toxic smoke or corrosive gas even when it should burn. Similar demand has been increasing also for the cable used for nuclear power plants. In this field, earnest desire has been made for the development of non-halogen flame-retardant cable having specific environmental resistance specially required at nuclear power plants in addition to the properties and capacities required in general industries. The authors have continued examinations on the anti-environmental properties of the materials for cable such as long heat resistance, radiation resistance, steam resistance and succeeded in completing various sorts of non-halogen flame-retardant cable for nuclear power plants. In this report, we will introduce various features of the cable we have developed this time as well as the long-term reliability of non-halogen flame-retardant materials. (author)

FIELD SCREENING FOR HALOGENATED VOLATILE ORGANIC COMPOUNDS

Energy Technology Data Exchange (ETDEWEB)

John F. Schabron; Joseph F. Rovani, Jr.; Theresa M. Bomstad

2003-07-01

Western Research Institute (WRI) is continuing work toward the development of new screening methodology and a test kit to measure halogenated volatile organic compounds (VOCs) in the field. Heated diode and corona discharge sensors are commonly used to detect leaks of refrigerants from air conditioners, freezers, and refrigerators. They are both selective to the presence of halogens. In prior work, the devices were tested for response to carbon tetrachloride, heptane, toluene, and water vapors. In the current work, sensor response was evaluated with sixteen halogenated VOCs relative to carbon tetrachloride. The results show that the response of the various chlorinated VOCs is within an order of magnitude of the response to carbon tetrachloride for each of the sensors. Thus, for field screening a single response factor can be used. Both types of leak detectors are being further modified to provide an on-board LCD signal readout, which is related to VOC concentration. The units will be fully portable and will operate with 115-V line or battery power. Signal background, noise level, and response data on the Bacharach heated diode detector and the TIF corona discharge detector show that when the response curves are plotted against the log of concentration, the plot is linear to the upper limit for the particular unit, with some curvature at lower levels. When response is plotted directly against concentration, the response is linear at the low end and is curved at the high end. The dynamic ranges for carbon tetrachloride of the two devices from the lower detection limit (S/N=2) to signal saturation are 4-850 vapor parts per million (vppm) for the corona discharge unit and 0.01-70 vppm for the heated diode unit. Additional circuit modifications are being made to lower the detection limit and increase the dynamic response range of the corona discharge unit. The results indicate that both devices show potential utility for future analytical method development work toward

Halogenation of Hydraulic Fracturing Additives in the Shale Well Parameter Space

Science.gov (United States)

Sumner, A. J.; Plata, D.

2017-12-01

Horizontal Drilling and Hydraulic fracturing (HDHF) involves the deep-well injection of a `fracking fluid' composed of diverse and numerous chemical additives designed to facilitate the release and collection of natural gas from shale plays. The potential impacts of HDHF operations on water resources and ecosystems are numerous, and analyses of flowback samples revealed organic compounds from both geogenic and anthropogenic sources. Furthermore, halogenated chemicals were also detected, and these compounds are rarely disclosed, suggesting the in situ halogenation of reactive additives. To test this transformation hypothesis, we designed and operated a novel high pressure and temperature reactor system to simulate the shale well parameter space and investigate the chemical reactivity of twelve commonly disclosed and functionally diverse HDHF additives. Early results revealed an unanticipated halogenation pathway of α-β unsaturated aldehyde, Cinnamaldehyde, in the presence of oxidant and concentrated brine. Ongoing experiments over a range of parameters informed a proposed mechanism, demonstrating the role of various shale-well specific parameters in enabling the demonstrated halogenation pathway. Ultimately, these results will inform a host of potentially unintended interactions of HDHF additives during the extreme conditions down-bore of a shale well during HDHF activities.

Evaluation of remaining behavior of halogen on the fabrication of MOX pellet containing Am

International Nuclear Information System (INIS)

Ozaki, Yoko; Osaka, Masahiko; Obayashi, Hiroshi; Tanaka, Kenya

2004-11-01

It is important to limit the content of halogen elements, namely fluorine and chlorine that are sources of making cladding material corrode, in nuclear fuel from the viewpoint of quality assurance. The halogen content should be more carefully limited in the MOX fuel containing Americium (Am-MOX), which is fabricated in the Alpha-Gamma Facility (AGF) for irradiation testing to be conducted in the experimental fast reactor JOYO, because fluorine may remain in the sintered pellets owing to a formation of AmF 3 known to have a low vapor pressure and may exceeds the limit of 25 ppm. In this study, a series of experimental determination of halogen element in Am-MOX were performed by a combination method of pyrolysis and ion-chromatography for the purpose of an evaluation of behavior of remaining halogen through the sintering process. Oxygen potential, temperature and time were changed as experimental parameters and their effects on the remaining behavior of halogen were examined. It was confirmed that good pellets, which contained small amount of halogen, could be obtained by the sintering for 3 hour at 1700degC in the oxygen potential range from -520 to -390 kJ/mol. In order to analysis of fluorine chemical form in green pellet, thermal analysis was performed. AmF 3 and PuF 3 have been confirmed to remain in the green pellet. (author)

Development of Halogen-free flame-retardant cable for nuclear power plant

International Nuclear Information System (INIS)

Ishii, Nobuhisa; Morii, Akira; Fujimura, Shunichi

1992-01-01

Conventional flame-retardant cables release a large volume of corrosive and toxic gases as well as smoke while combusted. Cables covered with halogen-free flame-retardant material, containing no halogen in it, have been developed to reduce generation of such gases and smoke, and have already been used in telecommunication service, subway and shipboard applications. However, for cables for nuclear power plant, covering materials should also have radiation resistance and other properties, including long-term physical stability. We have developed halogen-free flame-retardant cables for BWR nuclear power plant with sufficient flame retardancy radiation resistance and environmental resistance including steam-exposure resistance all of which are in accordance with Japanese specifications for BWR nuclear cables and have such characteristics as low corrosiveness, low toxicity and low smoke emission. (author)

Development of halogen-free flame-retardant cable for nuclear power plant

International Nuclear Information System (INIS)

Ishii, Nobuhisa; Morii, Akira; Fujimura, Shunichi

1991-01-01

Conventional flame-retardant cables release a large amount of corrosive and toxic gases and also smoke during combustion on fire. Cables covered with halogen-free flame-retardant material, containing no halogen in it, have been developed to reduce generation of such gases and smoke, and already used in telecommunication plant, subway and shipboard applications. In the case of nuclear power plant application, cable covering materials should also have radiation resistance and other properties including long-term physical stability. We have developed halogen-free flame-retardant cables for nuclear power plant with sufficient flame retardancy, radiation resistance, and environmental resistance including steam-exposure resistance, all of which are in accordance with Japanese specifications for nuclear cables, and with characteristics as low corrosiveness, low toxicity, and low smoke evolution. (author)

Halogen Bonding from Dispersion-Corrected Density-Functional Theory: The Role of Delocalization Error.

Science.gov (United States)

Otero-de-la-Roza, A; Johnson, Erin R; DiLabio, Gino A

2014-12-09

Halogen bonds are formed when a Lewis base interacts with a halogen atom in a different molecule, which acts as an electron acceptor. Due to its charge transfer component, halogen bonding is difficult to model using many common density-functional approximations because they spuriously overstabilize halogen-bonded dimers. It has been suggested that dispersion-corrected density functionals are inadequate to describe halogen bonding. In this work, we show that the exchange-hole dipole moment (XDM) dispersion correction coupled with functionals that minimize delocalization error (for instance, BH&HLYP, but also other half-and-half functionals) accurately model halogen-bonded interactions, with average errors similar to other noncovalent dimers with less charge-transfer effects. The performance of XDM is evaluated for three previously proposed benchmarks (XB18 and XB51 by Kozuch and Martin, and the set proposed by Bauzá et al.) spanning a range of binding energies up to ∼50 kcal/mol. The good performance of BH&HLYP-XDM is comparable to M06-2X, and extends to the "extreme" cases in the Bauzá set. This set contains anionic electron donors where charge transfer occurs even at infinite separation, as well as other charge transfer dimers belonging to the pnictogen and chalcogen bonding classes. We also show that functional delocalization error results in an overly delocalized electron density and exact-exchange hole. We propose intermolecular Bader delocalization indices as an indicator of both the donor-acceptor character of an intermolecular interaction and the delocalization error coming from the underlying functional.

Symmetric and asymmetric halogen-containing metallocarboranylporphyrins and uses thereof

Science.gov (United States)

Miura, Michiko; Wu, Haitao

2013-05-21

The present invention is directed to low toxicity boronated compounds and methods for their use in the treatment, visualization, and diagnosis of tumors. More specifically, the present invention is directed to low toxicity halogenated, carborane-containing 5,10,15,20-tetraphenylporphyrin compounds and methods for their use particularly in boron neutron capture therapy (BNCT) and photodynamic therapy (PDT) for the treatment of tumors of the brain, head and neck, and surrounding tissue. The invention is also directed to using these halogenated, carborane-containing tetraphenylporphyrin compounds in methods of tumor imaging and/or diagnosis such as MRI, SPECT, or PET.

Structure-Energy Relationships of Halogen Bonds in Proteins.

Science.gov (United States)

Scholfield, Matthew R; Ford, Melissa Coates; Carlsson, Anna-Carin C; Butta, Hawera; Mehl, Ryan A; Ho, P Shing

2017-06-06

The structures and stabilities of proteins are defined by a series of weak noncovalent electrostatic, van der Waals, and hydrogen bond (HB) interactions. In this study, we have designed and engineered halogen bonds (XBs) site-specifically to study their structure-energy relationship in a model protein, T4 lysozyme. The evidence for XBs is the displacement of the aromatic side chain toward an oxygen acceptor, at distances that are equal to or less than the sums of their respective van der Waals radii, when the hydroxyl substituent of the wild-type tyrosine is replaced by a halogen. In addition, thermal melting studies show that the iodine XB rescues the stabilization energy from an otherwise destabilizing substitution (at an equivalent noninteracting site), indicating that the interaction is also present in solution. Quantum chemical calculations show that the XB complements an HB at this site and that solvent structure must also be considered in trying to design molecular interactions such as XBs into biological systems. A bromine substitution also shows displacement of the side chain, but the distances and geometries do not indicate formation of an XB. Thus, we have dissected the contributions from various noncovalent interactions of halogens introduced into proteins, to drive the application of XBs, particularly in biomolecular design.

Rational design of organic semiconductors for texture control and self-patterning on halogenated surfaces

KAUST Repository

Ward, Jeremy W.; Li, Ruipeng; Obaid, Abdulmalik; Payne, Marcia M.; Smilgies, Detlef Matthias; Anthony, John Edward; Amassian, Aram; Jurchescu, Oana D.

2014-01-01

new materials. Here, the influence of the interactions at the interface between a halogenated organic semiconductor (OSC) thin film and a halogenated self-assembled monolayer on the formation of the crystalline texture directly affecting

Selective Nitrate Recognition by a Halogen-Bonding Four-Station [3]Rotaxane Molecular Shuttle.

Science.gov (United States)

Barendt, Timothy A; Docker, Andrew; Marques, Igor; Félix, Vítor; Beer, Paul D

2016-09-05

The synthesis of the first halogen bonding [3]rotaxane host system containing a bis-iodo triazolium-bis-naphthalene diimide four station axle component is reported. Proton NMR anion binding titration experiments revealed the halogen bonding rotaxane is selective for nitrate over the more basic acetate, hydrogen carbonate and dihydrogen phosphate oxoanions and chloride, and exhibits enhanced recognition of anions relative to a hydrogen bonding analogue. This elaborate interlocked anion receptor functions via a novel dynamic pincer mechanism where upon nitrate anion binding, both macrocycles shuttle from the naphthalene diimide stations at the periphery of the axle to the central halogen bonding iodo-triazolium station anion recognition sites to form a unique 1:1 stoichiometric nitrate anion-rotaxane sandwich complex. Molecular dynamics simulations carried out on the nitrate and chloride halogen bonding [3]rotaxane complexes corroborate the (1) H NMR anion binding results. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Singlet oxygen production by combining erythrosine and halogen light for photodynamic inactivation of Streptococcus mutans.

Science.gov (United States)

Fracalossi, Camila; Nagata, Juliana Yuri; Pellosi, Diogo Silva; Terada, Raquel Sano Suga; Hioka, Noboru; Baesso, Mauro Luciano; Sato, Francielle; Rosalen, Pedro Luiz; Caetano, Wilker; Fujimaki, Mitsue

2016-09-01

Photodynamic inactivation of microorganisms is based on a photosensitizing substance which, in the presence of light and molecular oxygen, produces singlet oxygen, a toxic agent to microorganisms and tumor cells. This study aimed to evaluate singlet oxygen quantum yield of erythrosine solutions illuminated with a halogen light source in comparison to a LED array (control), and the photodynamic effect of erythrosine dye in association with the halogen light source on Streptococcus mutans. Singlet oxygen quantum yield of erythrosine solutions was quantified using uric acid as a chemical-probe in an aqueous solution. The in vitro effect of the photodynamic antimicrobial activity of erythrosine in association with the halogen photopolimerizing light on Streptococcus mutans (UA 159) was assessed during one minute. Bacterial cultures treated with erythrosine alone served as negative control. Singlet oxygen with 24% and 2.8% degradation of uric acid in one minute and a quantum yield of 0.59 and 0.63 was obtained for the erythrosine samples illuminated with the halogen light and the LED array, respectively. The bacterial cultures with erythrosine illuminated with the halogen light presented a decreased number of CFU mL(-1) in comparison with the negative control, with minimal inhibitory concentrations between 0.312 and 0.156mgmL(-1). The photodynamic response of erythrosine induced by the halogen light was capable of killing S. mutans. Clinical trials should be conducted to better ascertain the use of erythrosine in association with halogen light source for the treatment of dental caries. Copyright © 2016 Elsevier B.V. All rights reserved.

On the ultrafast charge migration and subsequent charge directed reactivity in Cl⋯N halogen-bonded clusters following vertical ionization

International Nuclear Information System (INIS)

Chandra, Sankhabrata; Bhattacharya, Atanu; Periyasamy, Ganga

2015-01-01

In this article, we have presented ultrafast charge transfer dynamics through halogen bonds following vertical ionization of representative halogen bonded clusters. Subsequent hole directed reactivity of the radical cations of halogen bonded clusters is also discussed. Furthermore, we have examined effect of the halogen bond strength on the electron-electron correlation- and relaxation-driven charge migration in halogen bonded complexes. For this study, we have selected A-Cl (A represents F, OH, CN, NH 2 , CF 3 , and COOH substituents) molecules paired with NH 3 (referred as ACl:NH 3 complex): these complexes exhibit halogen bonds. To the best of our knowledge, this is the first report on purely electron correlation- and relaxation-driven ultrafast (attosecond) charge migration dynamics through halogen bonds. Both density functional theory and complete active space self-consistent field theory with 6-31 + G(d, p) basis set are employed for this work. Upon vertical ionization of NCCl⋯NH 3 complex, the hole is predicted to migrate from the NH 3 -end to the ClCN-end of the NCCl⋯NH 3 complex in approximately 0.5 fs on the D 0 cationic surface. This hole migration leads to structural rearrangement of the halogen bonded complex, yielding hydrogen bonding interaction stronger than the halogen bonding interaction on the same cationic surface. Other halogen bonded complexes, such as H 2 NCl:NH 3 , F 3 CCl:NH 3 , and HOOCCl:NH 3 , exhibit similar charge migration following vertical ionization. On the contrary, FCl:NH 3 and HOCl:NH 3 complexes do not exhibit any charge migration following vertical ionization to the D 0 cation state, pointing to interesting halogen bond strength-dependent charge migration

First principles study of halogens adsorption on intermetallic surfaces

International Nuclear Information System (INIS)

Zhu, Quanxi; Wang, Shao-qing

2016-01-01

Graphical abstract: - Highlights: • The linear relation between adsorbates induced work function change and dipole moment change also exists for intermetallic surfaces. • It is just a common linear relationship rather than a directly proportion. • A new weight parameter β is proposed to describe different factors effect on work function shift. - Abstract: Halides are often present at electrochemical environment, they can directly influence the electrode potential or zero charge potential through the induced work-function change. In this work, we focused in particular on the halogen-induced work function change as a function of the coverage of fluorine, chlorine, bromine and iodine on Al_2Au and Al_2Pt (110) surfaces. Results show that the real relation between work function change and dipole moment change for halogens adsorption on intermetallic surfaces is just a common linear relationship rather than a directly proportion. Besides, the different slopes between fitted lines and the theoretical slope employed in pure metal surfaces demonstrating that the halogens adsorption on intermetallic surfaces are more complicated. We also present a weight parameter β to describe different factors effect on work function shift and finally qualify which factor dominates the shift direction.

Isostructurality and non-isostructurality in the series of halogenated organic crystal substances. The structure of Hal-aggregates

International Nuclear Information System (INIS)

Grineva, O.V.; Zorkij, P.M.

2001-01-01

Local characteristics and the type of intermolecular Hal-aggregates (ensembles of contacting halogen atoms of adjacent molecules) present in chemically similar halogenated crystal substances, differing only in the nature of Hal atoms, are compared. 23 series of halogenated hydrocarbons, including 57 crystal structures were considered. A clearly pronounced specificity of Hal-aggregates for compounds with a low and intermediate content of halogen was revealed. It was found that, as a rule, coordination number of Hal atom by Hal adjacent atoms increases in the series F-Cl-Br-I [ru

Halogens in pore water of peat bogs – the role of peat decomposition and dissolved organic matter

Directory of Open Access Journals (Sweden)

H. Biester

2006-01-01

Full Text Available Halogens are strongly enriched in peat and peatlands and such they are one of their largest active terrestrial reservoir. The enrichment of halogens in peat is mainly attributed to the formation of organohalogens and climatically controlled humification processes. However, little is known about release of halogens from the peat substrate and the distribution of halogens in the peat pore water. In this study we have investigated the distribution of chlorine, bromine and iodine in pore water of three pristine peat bogs located in the Magellanic Moorlands, southern Chile. Peat pore waters were collected using a sipping technique, which allows in situ sampling down to a depth greater than 6m. Halogens and halogen species in pore water were determined by ion-chromatography (IC (chlorine and IC-ICP-MS (bromine and iodine. Results show that halogen concentrations in pore water are 15–30 times higher than in rainwater. Mean concentrations of chlorine, bromine and iodine in pore water were 7–15 mg l−1, 56–123 μg l−1, and 10–20 μg l−1, which correspond to mean proportions of 10–15%, 1–2.3% and 0.5–2.2% of total concentrations in peat, respectively. Organobromine and organoiodine were the predominant species in pore waters, whereas chlorine in pore water was mostly chloride. Advection and diffusion of halogens were found to be generally low and halogen concentrations appear to reflect release from the peat substrate. Release of bromine and iodine from peat depend on the degree of peat degradation, whereas this relationship is weak for chlorine. Relatively higher release of bromine and iodine was observed in less degraded peat sections, where the release of dissolved organic carbon (DOC was also the most intensive. It has been concluded that the release of halogenated dissolved organic matter (DOM is the predominant mechanism of iodine and bromine release from peat.

Halogen poisoning effect of Pt-TiO{sub 2} for formaldehyde catalytic oxidation performance at room temperature

Energy Technology Data Exchange (ETDEWEB)

Zhu, Xiaofeng; Cheng, Bei [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122#, Wuhan 430070 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122#, Wuhan 430070 (China); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Ho, Wingkei, E-mail: keithho@ied.edu.hk [Department of Science and Environmental Studies and Centre for Education in Environmental Sustainability, The Hong Kong Institute of Education, Tai Po, N.T. Hong Kong (China)

2016-02-28

Graphical abstract: - Highlights: • The Pt-TiO{sub 2} catalyst is deactivated by adsorption of halogen ions. • The halogen poison is mainly attributed to the active site blocking of the Pt surface. • Halogen ions and Pt form Pt−X coordination bonds. • Large halogen diameter exhibits severe poisoning effect. - Abstract: Catalytic decomposition of formaldehyde (HCHO) at room temperature is an important method for HCHO removal. Pt-based catalysts are the optimal catalyst for HCHO decomposition at room temperature. However, the stability of this catalyst remains unexplored. In this study, Pt-TiO{sub 2} (Pt-P25) catalysts with and without adsorbed halogen ions (including F{sup −}, Cl{sup −}, Br{sup −}, and I{sup −}) were prepared through impregnation and ion modification. Pt-TiO{sub 2} samples with adsorbed halogen ions exhibited reduced catalytic activity for formaldehyde decomposition at room temperature compared with the Pt-TiO{sub 2} sample; the catalytic activity followed the order of F-Pt-P25, Cl-Pt-P25, Br-Pt-P25, and I-Pt-P25. Characterization results (including XRD, TEM, HRTEM, BET, XPS, and metal dispersion) showed that the adsorbed halogen ions can poison Pt nanoparticles (NPs), thereby reducing the HCHO oxidation activity of Pt-TiO{sub 2}. The poison mechanism is due to the strong adsorption of halogen ions on the surface of Pt NPs. The adsorbed ions form coordination bonds with surface Pt atoms by transferring surplus electrons into the unoccupied 5d orbit of the Pt atom, thereby inhibiting oxygen adsorption and activation of the Pt NP surface. Moreover, deactivation rate increases with increasing diameter of halogen ions. This study provides new insights into the fabrication of high-performance Pt-based catalysts for indoor air purification.

On the ultrafast charge migration and subsequent charge directed reactivity in Cl⋯N halogen-bonded clusters following vertical ionization

Energy Technology Data Exchange (ETDEWEB)

Chandra, Sankhabrata; Bhattacharya, Atanu, E-mail: atanub@ipc.iisc.ernet.in [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore (India); Periyasamy, Ganga [Department of Chemistry, Central College Campus, Bangalore University, Bangalore (India)

2015-06-28

In this article, we have presented ultrafast charge transfer dynamics through halogen bonds following vertical ionization of representative halogen bonded clusters. Subsequent hole directed reactivity of the radical cations of halogen bonded clusters is also discussed. Furthermore, we have examined effect of the halogen bond strength on the electron-electron correlation- and relaxation-driven charge migration in halogen bonded complexes. For this study, we have selected A-Cl (A represents F, OH, CN, NH{sub 2}, CF{sub 3}, and COOH substituents) molecules paired with NH{sub 3} (referred as ACl:NH{sub 3} complex): these complexes exhibit halogen bonds. To the best of our knowledge, this is the first report on purely electron correlation- and relaxation-driven ultrafast (attosecond) charge migration dynamics through halogen bonds. Both density functional theory and complete active space self-consistent field theory with 6-31 + G(d, p) basis set are employed for this work. Upon vertical ionization of NCCl⋯NH{sub 3} complex, the hole is predicted to migrate from the NH{sub 3}-end to the ClCN-end of the NCCl⋯NH{sub 3} complex in approximately 0.5 fs on the D{sub 0} cationic surface. This hole migration leads to structural rearrangement of the halogen bonded complex, yielding hydrogen bonding interaction stronger than the halogen bonding interaction on the same cationic surface. Other halogen bonded complexes, such as H{sub 2}NCl:NH{sub 3}, F{sub 3}CCl:NH{sub 3}, and HOOCCl:NH{sub 3}, exhibit similar charge migration following vertical ionization. On the contrary, FCl:NH{sub 3} and HOCl:NH{sub 3} complexes do not exhibit any charge migration following vertical ionization to the D{sub 0} cation state, pointing to interesting halogen bond strength-dependent charge migration.

Retention of Halogenated Solutes on Stationary Phases Containing Heavy Atoms

Directory of Open Access Journals (Sweden)

Toshio Miwa

2013-05-01

Full Text Available To examine the effects of weak intermolecular interactions on solid-phase extraction (SPE and chromatographic separation, we synthesized some novel stationary phases with a heavy atom effect layer by immobilizing halogenated aromatic rings and hydroxyl groups onto the surface of a hydrophilic base polymer. Using SPE cartridges packed with the functionalized materials, we found that the heavy atom stationary phases could selectively retain halophenols in organic solvents, such as 1-propanol which blocks the hydrogen bonding, or acetonitrile which blocks the p-p interaction. The extraction efficiency of the materials toward the halophenols depended on the dipole moments of phenoxy groups present as functional groups. On the other hand, the extraction efficiency of solutes toward the functional group depended on their molar refractions, i.e., induced dipole moments. The retention of the solutes to the stationary phase ultimately depended on not only strong intermolecular interactions, but also the effects of weak interactions such as the dispersion force.

Iron Mineral Catalyzed C-H Activation As a Potential Pathway for Halogenation Processes

Science.gov (United States)

Tubbesing, C.; Schoeler, H. F.; Benzing, K.; Krause, T.; Lippe, S.; Rudloff, M.

2014-12-01

Due to increasing drinking water demand of mankind and an expected climate change the impact of salt lakes and salt deserts will increase within the next decades. Furthermore, a rising sea level influences coastal areas like salt marshes and abets processes which will lead to elevated organohalogen formation. An additional increase of the global warming potential, of particle formation and stratospheric ozone depletion is expected. Understanding these multifaceted processes is essential for mankind to be prepared for these alterations of the atmosphere. For example, Keppler et al. (2000) described the production of volatile halogenated organic compounds via oxidation of organic matter driven by ferric iron. However, the formation of long-chained alkyl halides in salt lakes is yet undisclosed. Despite the relative "inertness" of alkanes a direct halogenation of these compounds might be envisaged. In 2005 Vaillancourt et al. discovered a nonheme iron enzyme which is able to halogenate organic compounds via generating the high valent ferryl cation as reaction center. Based on various publications about C-H activation (Bergman, 2007) we postulate a halogenation process in which an iron containing minerals catalyse the C-H bond cleavage of organic compounds in soils. The generated organic radicals are highly reactive towards halides connected to the iron complex. We suggest that next to diagenetically altered iron containing enzymes, minerals such as oxides, hydroxides and sulfides are involved in abiotic halogenation processes. We applied the amino acid methionine as organic model compound and soluble iron species as reactants. All samples were incubated in aqueous phases containing various NaCl concentrations. As a result various halogenated ethanes and ethenes were identified as reaction products. References Bergman, R. G. (2007) Nature, 446(7134) 391-393 Keppler, F., et al. (2000) Nature, 403(6767) 298-301 Vaillancourt, F. H., et al. (2005) Nature, 436(7054) 1191-1194

Development of halogen-free, heat-resistant, low-voltage wire for automotive use

International Nuclear Information System (INIS)

Ueno, Keiji; Suzuki, Sizuo; Takahagi, Masatoshi; Uda, Ikujiro

1995-01-01

The environmental load of our motorized society is of major concern, and includes considerations of recycling of automotive parts as the industrial wastes. The total average length of AV, AVX (electrical wire insulated with PVC, cross-linked PVC), and AEX (electrical wire insulated with cross-linked polyolefin) wires required for the harnesses in modern automobiles is approximately 2,000-3,000 meters per unit. However these electrical wires contain a large amount of halogen, which can generate the smoke and corrosive gas. In response to this problem the authors have developed the electron beam irradiated halogen-free, heat-resistant, low-voltage electrical wire which does not contain any halogen based polymer or flame retardants. The developed wire features the reliability equivalent to AEX wire with minimum environmental load. (Author)

Process for forming epitaxial perovskite thin film layers using halide precursors

Science.gov (United States)

Clem, Paul G.; Rodriguez, Mark A.; Voigt, James A.; Ashley, Carol S.

2001-01-01

A process for forming an epitaxial perovskite-phase thin film on a substrate. This thin film can act as a buffer layer between a Ni substrate and a YBa.sub.2 Cu.sub.3 O.sub.7-x superconductor layer. The process utilizes alkali or alkaline metal acetates dissolved in halogenated organic acid along with titanium isopropoxide to dip or spin-coat the substrate which is then heated to about 700.degree. C. in an inert gas atmosphere to form the epitaxial film on the substrate. The YBCO superconductor can then be deposited on the layer formed by this invention.

Recoil halogen reactions in liquid and frozen aqueous solutions of biomolecules

International Nuclear Information System (INIS)

Arsenault, L.J.; Blotcky, A.J.; Firouzbakht, M.L.; Rack, E.P.; Nebraska Univ., Omaha

1982-01-01

Reactions of recoil 38 Cl, 80 Br and 128 I have been studied in crystalline systems of 5-halouracil, 5-halo-2'-deoxyuridine and 5-halouridine as well as liquid and frozen aqueous solutions of these halogenated biomolecules. In all systems expect crystalline 5-iuodouracil the major product was the radio-labelled halide ion. There was no evidence for other halogen inorganic species. The major labelled organic product was the parent molecule. A recoil atom tracer technique was developed to acquire site information of the biomolecule solutes in the liquid and frozen aqueous systems. For all liquid and frozen aqueous systems, the halogenated biomolecules tended to aggregate. For liquid systems, the tendency for aggregation diminished as the solute concentration approached zero, where the probable state of the solute approached a monomolecular dispersion. Unlike the liquid state, the frozen ice lattice demonstated a ''caging effect'' for the solute aggregates which resulted in constant product yields over the whole concentration range. (orig.)

Environmental levels and toxicological potencies of a novel mixed halogenated carbazole

Directory of Open Access Journals (Sweden)

Miren Pena-Abaurrea

2016-09-01

Full Text Available The present work involves an extensive analytical and toxicological description of a recently identified mixed halogenated carbazole found in sediment samples, 1,8-dibromo-3,6-dichloro-9H-carbazole (BCCZ. Concentrations and the relative effect potency (REP were calculated for the target BCCZ in a set of stream sediments collected in 2008 in Ontario, Canada. The levels calculated for BCCZ as compared to those previously assessed for legacy persistent organic pollutants (POPs in the same samples revealed a significant contribution of BCCZ to the total organic chemical contamination (<1%–95%; average 37%. The corresponding dioxin toxic equivalencies (TEQs of BCCZ in the sediment extracts were estimated from experimental REP data. The experimental data presented supports the classification of this emerging halogenated chemical as a contaminant of emerging environmental concern. Although potential emission sources could not be identified, this study highlights the importance of on-going research for complete characterization of halogenated carbazoles and related compounds.

Determination Of Refractive Index And Reflectivity Of Thin Layer With Optical Absorption Method; PENENTUAN INDEKS BIAS DAN REFLEKTIVITAS LAPISAN TIPIS DENGAN METODA SERAPAN OPTIK

Energy Technology Data Exchange (ETDEWEB)

Hariyanto, Sigit; Budianto, Anwar; Subarkah,; Atmono, Trimarji [Yogyakarta Nuclear Research Center, National Nuclear Energy Agency, Yogyakarta (Indonesia)

1996-04-15

. The refractive index and reflectivity of ASi:H and Si Ox thin layer have been observed by optical absorption methods. Measurement has been done after the preparation of optical system which consists of a halogen lamp light source, monochromator, sample and light detector. The Monochromator output showed that measured halogen lamp spectrum light is between 470 nm -750 nm. The maximum voltage of halogen lamp is 220 Volt, the output light increases in intensity while the wave length increases. The inclination of intensity decrease at the wave length of 725 nm. The result of the calculation of refractive index varies in accordance with the wave length. The average refractive index of ASi:H is nf a = 1.753. The total reflectivity of air-thin layer-substrate is Rt a = 0.315. The refractive index of Si Ox sample is nf b2.182 and the total reflectivity is Rt b=O,514.

Development of no halogen incombustible cables for atomic energy

International Nuclear Information System (INIS)

Ishii, Nobumasa; Kimura, Hitoshi; Fujimura, Shun-ichi

1990-01-01

In upgrading light water reactor technology, it is important to improve the reliability of machinery and equipment, to make regular inspection efficient, to extend the period of continuous operation, to optimize operation cycle and to improve the maintainability of plant facilities. For the cables for nuclear power stations, high incombustibility is required, and at present halogen system incombustible materials are used. Recently the development of no halogen incombustible cables has been advanced, with which the generation of corrosive gas and smoke at the time of fires is slight. In this study, the application of such no halogen incombustible cables to nuclear power stations and the improvement of reliability of the cables were investigated. The cables to be developed are those for electric power, control and instrumentation in BWR plants and insulated electric wires. The required characteristics are incombustibility, no generation of smoke and corrosive gas at the time of fires, radiation resistance and steam resistance in LOCA. The selection of base polymers, metal hydrates and radiation protectors, the evaluation of radiation resistance and steam resistance, the examination of the corrosive and poisonous properties of generated gas and smoke generation and so on are reported. The development was successful. (K.I.)

Chlorine dioxide as phenol and H2S scavenger - formation of halogenated phenols and subsequent environmental risk

Energy Technology Data Exchange (ETDEWEB)

Melbye, Alf G.; Faksness, Liv-Guri; Knudsen, Boerre Leif

2006-03-15

Formation of halogenated phenols as side products from treatment of produced water with aqueous chlorine dioxide has been investigated. The literature describes formation of halogenated hydrocarbons in effluent treatment using chlorine, hypochlorite and chlorine dioxide. A new chlorine dioxide product, originally intended as a H2S scavenger in the oil and gas industry, has been tested both as a phenol scavenger and H2S-scavenger for produced water applications. The concern about the possible formation of halogenated by-products initiated laboratory testing of chlorine dioxide as phenol and H2S scavenger for produced water applications. The tests also included synthetic matrixes containing phenols, and the tests show that halogenated phenols, mainly brominated species, are found in produced water after treatment with chlorine dioxide. Due to potential environmental risk from halogenated organic contaminants, the use of chlorine dioxide as phenol and H2S scavenger is not recommended. (Author)

Determination of N-containing halogenated natural products using gas chromatography in combination of a nitrogen-phosphorus-detector

Energy Technology Data Exchange (ETDEWEB)

Melcher, J.; Vetter, W. [Hohenheim Univ., Stuttgart (Germany). Inst. fuer Lebensmittelchemie

2004-09-15

In the last few years several nonpolar halogenated natural products (HNPs) such as Q1, MHC-1, BC-2, BC-3, BC-10 were detected at elevated concentrations in marine biota samples. In addition, there are still some abundant peaks of halogenated compounds frequently found in the gas chromatograms of many marine samples which have not yet been identified. Some of the known halogenated natural products (Q1, HDBPs including BC-10, bromoindoles) contain N-heterocyclic backbones. Since nitrogen is scarcely found in anthropogenic halogenated compounds, the detection of N-containing halogenated substances may be used as a first indicator for the presence of HNPs in a sample extract. In the presented method we studied the suitability of a nitrogen phosphorous detector (NPD) for quantification of Q1 and the detection of Ncontaining compounds in marine biota. Analyses were accompanied with GC/ECD analyses.

A 19F NMR study of C-I....pi- halogen bonding

DEFF Research Database (Denmark)

Hauchecorne, Dieter; vand er Veken, Benjamin J.; Herrebout, Wouter A.

2011-01-01

The formation of halogen bonded complexes between toluene-d8 and the perfluoroiodopropanes 1-C3F7I and 2-C3F7I has been investigated using 19F NMR spectroscopy. For both Lewis acids, evidence was found for the formation of a C–I⋯π halogen bonded complex. The complex formed is a 1:1 type. Using sp...... results are supported by ab initio calculations at the B3LYP-PCM/6-311++G(d,p) + LanL2DZ∗ level....

Are superhalogens without halogen ligand capable of transcending traditional halogen-based superhalogens? Ab initio case study of binuclear anions based on pseudohalogen ligand

Science.gov (United States)

Li, Jin-Feng; Sun, Yin-Yin; Bai, Hongcun; Li, Miao-Miao; Li, Jian-Li; Yin, Bing

2015-06-01

The superhalogen properties of polynuclear structures without halogen ligand are theoretically explored here for several [M2(CN)5]-1 (M = Ca, Be) clusters. At CCSD(T) level, these clusters have been confirmed to be superhalogens due to their high vertical electron detachment energies (VDE). The largest one is 9.70 eV for [Ca2(CN)5]-1 which is even higher than those of corresponding traditional structures based on fluorine or chlorine ligands. Therefore the superhalogens stronger than the traditional halogen-based structures could be realized by ligands other than halogen atoms. Compared with CCSD(T), outer valence Green's function (OVGF) method either overestimates or underestimates the VDEs for different structures while MP2 results are generally consistent in the aspect of relative values. The extra electrons of the highest VDE anions here aggregate on the bridging CN units with non-negligible distribution occurring on other CN units too. These two features lower both the potential and kinetic energies of the extra electron respectively and thus lead to high VDE. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to the detachment of cyanide ligand were also investigated. The sum of these results identifies the potential of polynuclear structures with pseudohalogen ligand as suitable candidates with enhanced superhalogens properties.

Halogen bond tunability II: the varying roles of electrostatic and dispersion contributions to attraction in halogen bonds

Czech Academy of Sciences Publication Activity Database

Riley, Kevin Eugene; Murray, J. S.; Fanfrlík, Jindřich; Řezáč, Jan; Solá, R. J.; Concha, M. C.; Ramos, F. M.; Politzer, P.

2013-01-01

Roč. 19, č. 11 (2013), s. 4651-4659 ISSN 1610-2940 R&D Projects: GA ČR GBP208/12/G016 Grant - others:Operational Program Research and Development for Innovations(XE) CZ.1.05/2.1.00/03.0058 Institutional support: RVO:61388963 Keywords : dispersion * electrostatics * halogen bonding * noncovalent interactions Subject RIV: CE - Biochemistry Impact factor: 1.867, year: 2013

Tuning the viscosity of halogen free bulk heterojunction inks for inkjet printed organic solar cells

NARCIS (Netherlands)

Lamont, C.A.; Eggenhuisen, T.M.; Coenen, M.J.J.; Slaats, T.W.L.; Andriessen, R.; Groen, P.

2015-01-01

For the solution processing of organic photovoltaics on an industrial scale, the exclusion of halogenated solvents is a necessity. However, the limited solubility of most semiconducting polymer/fullerene blends in non-halogenated solvents results in ink formulations with low viscosities which poses

Impact of enhanced ozone deposition and halogen chemistry on tropospheric ozone over the Northern Hemisphere

Science.gov (United States)

Fate of ozone in marine environments has been receiving increased attention due to the tightening of ambient air quality standards. The role of deposition and halogen chemistry is examined through incorporation of an enhanced ozone deposition algorithm and inclusion of halogen ch...

Chalcogen- and halogen-bonds involving SX2 (X = F, Cl, and Br) with formaldehyde.

Science.gov (United States)

Mo, Lixin; Zeng, Yanli; Li, Xiaoyan; Zhang, Xueying; Meng, Lingpeng

2016-07-01

The capacity of SX2 (X = F, Cl, and Br) to engage in different kinds of noncovalent bonds was investigated by ab initio calculations. SCl2 (SBr2) has two σ-holes upon extension of Cl (Br)-S bonds, and two σ-holes upon extension of S-Cl (Br) bonds. SF2 contains only two σ-holes upon extension of the F-S bond. Consequently, SCl2 and SBr2 form chalcogen and halogen bonds with the electron donor H2CO while SF2 forms only a chalcogen bond, i.e., no F···O halogen bond was found in the SF2:H2CO complex. The S···O chalcogen bond between SF2 and H2CO is the strongest, while the strongest halogen bond is Br···O between SBr2 and H2CO. The nature of these two types of noncovalent interaction was probed by a variety of methods, including molecular electrostatic potentials, QTAIM, energy decomposition, and electron density shift maps. Termolecular complexes X2S···H2CO···SX'2 (X = F, Cl, Br, and X' = Cl, Br) were constructed to study the interplay between chalcogen bonds and halogen bonds. All these complexes contained S···O and Cl (Br)···O bonds, with longer intermolecular distances, smaller values of electron density, and more positive three-body interaction energies, indicating negative cooperativity between the chalcogen bond and the halogen bond. In addition, for all complexes studied, interactions involving chalcogen bonds were more favorable than those involving halogen bonds. Graphical Abstract Molecular electrostatic potential and contour map of the Laplacian of the electron density in Cl2S···H2CO···SCl2 complex.

Flame retardant synergism between molybdenum and halogen-containing compounds in unsaturated polyesters. [Smoke suppression

Energy Technology Data Exchange (ETDEWEB)

Skinner, G.A.; Parker, L.E.; Marshall, P.J.

1978-01-01

Oxygen index results for a series of unsaturated polyesters, containing molybdenum oxide and various halogenated compounds, have provided definite evidence for some form of flame retardant synergistic effect between molybdenum and halogen. With the halogenated compounds used, the magnitude of the effect was greater in the presence of bromine but was dependent on the type of compound. When dibromoneopentyl glycol was used as the bromine source, the synergistic effect exhibited by molybdenum oxide was comparable to that shown by antimony oxide. Since molybdenum oxide also acts as a smoke suppressant, it could offer a useful alternative to antimony oxide particularly in the light of probable changes in standards and regulatory control regarding smoke emission. 4 figures, 2 tables.

Study of the halogenation of EuBa[sub 2]Cu[sub 3]O[sub 6]. Etude de l'halogenation de EuBa[sub 2]Cu[sub 3]O[sub 6

Energy Technology Data Exchange (ETDEWEB)

Kabeya, D.T. (Rennes-1 Univ., 35 (France). Lab. de Chimie du Solide et Inorganique Moleculaire); Mokhtari, M. (Rennes-1 Univ., 35 (France). Lab. de Chimie du Solide et Inorganique Moleculaire); Perrin, C. (Rennes-1 Univ., 35 (France). Lab. de Chimie du Solide et Inorganique Moleculaire); Sergent, M. (Rennes-1 Univ., 35 (France). Lab. de Chimie du Solide et Inorganique Moleculaire); Grushko, Yu. (Russian Academy of Sciences, Gatchina (Russian Federation). Nuclear Physics Inst.); Kokovina, L. (Russian Academy of Sciences, Gatchina (Russian Federation). Nuclear Physics Inst.); Rozhniakova, N. (Russian Academy of Sciences, Gatchina (Russian Federation). Nuclear Physics Inst.)

1994-11-01

Sintered samples of EuBa[sub 2]Cu[sub 3]O[sub 6] have been halogenated at low temperature (t<300 C) by treatments under NF[sub 3] or CCl[sub 4] flow diluted in nitrogen, or by reaction with iodine in sealed tubes. Such mild conditions of synthesis allowed to avoid the decomposition of the material during the reactions. The incorporation of the halogen in the sample has been evidenced by the weight gain, by the evolution of the unit-cell parameters and by SEM and EDS analyses. After fluorination and chlorination, the samples become superconducting, but no superconducting behaviour is observed after iodination. These results are compared to the ones previously obtained during the halogenation of YBa[sub 2]Cu[sub 3]O[sub 6]. (orig.).

UARS Halogen Occultation Experiment (HALOE) Level 2 V001

Data.gov (United States)

National Aeronautics and Space Administration — The HALOE home page on the WWW is http://haloe.gats-inc.com/home/index.php The Halogen Occultation Experiment (HALOE) on NASA's Upper Atmosphere Research Satellite...

Biogas from MSW landfill: Composition and determination of chlorine content with the AOX (adsorbable organically bound halogens) technique

International Nuclear Information System (INIS)

Rey, M.D.; Font, R.; Aracil, I.

2013-01-01

An exhaustive characterization of the biogas from some waste disposal facilities has been carried out. The analysis includes the main components (methane, carbon dioxide, nitrogen and oxygen) as well as trace components such as hydrogen sulphide, ammonia and VOCs (volatile organic compounds) including siloxanes and halogenated compounds. VOCs were measured by GC/MS (Gas Chromatography/Mass Spectrometry) using two different procedures: thermal desorption of the Tenax TA and Carbotrap 349 tubes and SPME (Solid Phase Micro-Extraction). A method has been established to measure the total halogen content of the biogas with the AOX (adsorbable organically bound halogens) technique. The equipment used to analyze the samples was a Total Organic Halogen Analyzer (TOX-100). Similar results were obtained when comparing the TOX (Total Organic Halogen) values with those obtained by GC/MS. The halogen content in all the samples was under 22 mg Cl/Nm 3 which is below the limit of 150 mg/Nm 3 proposed in the Spanish Regulations for any use of the biogas. The low chlorine content in the biogas studied, as well as the low content of other trace compounds, makes it suitable for use as a fuel for electricity generating engines

Biogenic halocarbons from coastal oceanic upwelling regions as tropospheric halogen source

Science.gov (United States)

Krüger, Kirstin; Fuhlbrügge, Steffen; Hepach, Helmke; Fiehn, Alina; Atlas, Elliot; Quack, Birgit

2016-04-01

Halogenated very short lived substances (VSLS) are naturally produced in the ocean and emitted to the atmosphere. Recently, oceanic upwelling regions in the tropical East Atlantic were identified as strong sources of brominated halocarbons to the troposphere. During a cruise of R/V METEOR in December 2012 the oceanic sources and emissions of various halogenated trace gases and their mixing ratios in the marine atmospheric boundary layer (MABL) were investigated above the Peruvian Upwelling for the first time. This study presents novel observations of the three VSLS bromoform, dibromomethane and methyl iodide together with high resolution meteorological measurements and Lagrangian transport modelling. Although relatively low oceanic emissions were observed, except for methyl iodide, surface atmospheric abundances were elevated. Radiosonde launches during the cruise revealed a low, stable MABL and a distinct trade inversion above acting both as strong barriers for convection and trace gas transport in this region. Significant correlations between observed atmospheric VSLS abundances, sea surface temperature, relative humidity and MABL height were found. We used a simple source-loss estimate to identify the contribution of oceanic emissions to observed atmospheric concentrations which revealed that the observed marine VSLS abundances were dominated by horizontal advection below the trade inversion. The observed VSLS variations can be explained by the low emissions and their accumulation under different MABL and trade inversion conditions. Finally, observations from a second Peruvian Upwelling cruise with R/V SONNE during El Nino in October 2015 will be compared to highlight the role of different El Nino Southern Oscillation conditions. This study confirms the importance of coastal oceanic upwelling and trade wind systems on creating effective transport barriers in the lowermost atmosphere controlling the distribution of VSLS abundances above coastal ocean upwelling

Are superhalogens without halogen ligand capable of transcending traditional halogen-based superhalogens? Ab initio case study of binuclear anions based on pseudohalogen ligand

International Nuclear Information System (INIS)

Li, Jin-Feng; Sun, Yin-Yin; Li, Miao-Miao; Li, Jian-Li; Yin, Bing; Bai, Hongcun

2015-01-01

The superhalogen properties of polynuclear structures without halogen ligand are theoretically explored here for several [M 2 (CN) 5 ] −1 (M =  Ca, Be) clusters. At CCSD(T) level, these clusters have been confirmed to be superhalogens due to their high vertical electron detachment energies (VDE). The largest one is 9.70 eV for [Ca 2 (CN) 5 ] −1 which is even higher than those of corresponding traditional structures based on fluorine or chlorine ligands. Therefore the superhalogens stronger than the traditional halogen-based structures could be realized by ligands other than halogen atoms. Compared with CCSD(T), outer valence Green’s function (OVGF) method either overestimates or underestimates the VDEs for different structures while MP2 results are generally consistent in the aspect of relative values. The extra electrons of the highest VDE anions here aggregate on the bridging CN units with non-negligible distribution occurring on other CN units too. These two features lower both the potential and kinetic energies of the extra electron respectively and thus lead to high VDE. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to the detachment of cyanide ligand were also investigated. The sum of these results identifies the potential of polynuclear structures with pseudohalogen ligand as suitable candidates with enhanced superhalogens properties

Are superhalogens without halogen ligand capable of transcending traditional halogen-based superhalogens? Ab initio case study of binuclear anions based on pseudohalogen ligand

Energy Technology Data Exchange (ETDEWEB)

Li, Jin-Feng; Sun, Yin-Yin; Li, Miao-Miao; Li, Jian-Li; Yin, Bing, E-mail: rayinyin@nwu.edu.cn [MOE Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710069 (China); Bai, Hongcun [Key Laboratory of Energy Source and Chemical Engineering, Ningxia University, Yinchuan, Ningxia 750021 (China)

2015-06-15

The superhalogen properties of polynuclear structures without halogen ligand are theoretically explored here for several [M{sub 2}(CN){sub 5}]{sup −1} (M =  Ca, Be) clusters. At CCSD(T) level, these clusters have been confirmed to be superhalogens due to their high vertical electron detachment energies (VDE). The largest one is 9.70 eV for [Ca{sub 2}(CN){sub 5}]{sup −1} which is even higher than those of corresponding traditional structures based on fluorine or chlorine ligands. Therefore the superhalogens stronger than the traditional halogen-based structures could be realized by ligands other than halogen atoms. Compared with CCSD(T), outer valence Green’s function (OVGF) method either overestimates or underestimates the VDEs for different structures while MP2 results are generally consistent in the aspect of relative values. The extra electrons of the highest VDE anions here aggregate on the bridging CN units with non-negligible distribution occurring on other CN units too. These two features lower both the potential and kinetic energies of the extra electron respectively and thus lead to high VDE. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to the detachment of cyanide ligand were also investigated. The sum of these results identifies the potential of polynuclear structures with pseudohalogen ligand as suitable candidates with enhanced superhalogens properties.

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.

Ab Initio Calculations on Halogen Bond Between N-Br and Electron-donating Groups

Institute of Scientific and Technical Information of China (English)

WANG Yan-hua; CHEN Xue-song; ZOU Jian-wei; YU Qing-sen

2007-01-01

Ab initio calculations of complexes formed between N-bromosuccinimide and a series of electron-donating groups were performed at the level of MP2/Lanl2DZ* to gain a deeper insight into the nature of the N-Br halogen stronger halogen-bonding complex than the C-Br. A comparison of neutral hydrogen bond complex series reveals that the electron-donating capacities of the atoms decrease in the order, N＞O＞S; O(sp3)＞O(sp2), which is adequate for the C-Br halogen bonding. Interaction energies, in conjunction with the geometrical parameters show that the affinitive capacity of trihalide anions X-3 with N-bromosuccinimide are markedly lower than that of the corresponding X- with N-bromosuccinimide, even lower than those of neutral molecules with N-bromosuccinimide. AIM analyses further confirmed the above results.

Selenium-Mediated Dehalogenation of Halogenated Nucleosides and its Relevance to the DNA Repair Pathway.

Science.gov (United States)

Mondal, Santanu; Manna, Debasish; Mugesh, Govindasamy

2015-08-03

Halogenated nucleosides can be incorporated into the newly synthesized DNA of replicating cells and therefore are commonly used in the detection of proliferating cells in living tissues. Dehalogenation of these modified nucleosides is one of the key pathways involved in DNA repair mediated by the uracil-DNA glycosylase. Herein, we report the first example of a selenium-mediated dehalogenation of halogenated nucleosides. We also show that the mechanism for the debromination is remarkably different from that of deiodination and that the presence of a ribose or deoxyribose moiety in the nucleosides facilitates the deiodination. The results described herein should help in understanding the metabolism of halogenated nucleosides in DNA and RNA. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toward hydrogen detection at room temperature with printed ZnO nanoceramics films activated with halogen lighting

Science.gov (United States)

Nguyen, Van Son; Jubera, Véronique; Garcia, Alain; Debéda, Hélène

2015-12-01

Though semiconducting properties of ZnO have been extensively investigated under hazardous gases, research is still necessary for low-cost sensors working at room temperature. Study of printed ZnO nanopowders-based sensors has been undertaken for hydrogen detection. A ZnO paste made with commercial nanopowders is deposited onto interdigitated Pt electrodes and sintered at 400 °C. The ZnO layer structure and morphology are first examined by XRD, SEM, AFM and emission/excitation spectra prior to the study of the effect of UV-light on the electrical conduction of the semiconductor oxide. The response to hydrogen exposure is subsequently examined, showing that low UV-light provided by halogen lighting enhances the gas response and allows detection at room temperature with gas responses similar to those obtained in dark conditions at 150 °C. A gas response of 44% (relative change in current) under 300 ppm is obtained at room temperature. Moreover, it is demonstrated that very low UV-light power (15 μW/mm2) provided by the halogen lamp is sufficient to give sensitivities as high as those for much higher powers obtained with a UV LED (7.7 mW/mm2). These results are comparable to those obtained by others for 1D or 2D ZnO nanostructures working at room temperature or at temperatures up to 250 °C.

The rat IgGFcγBP and Muc2 C-terminal domains and TFF3 in two intestinal mucus layers bind together by covalent interaction.

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Hao Yu

Full Text Available The secreted proteins from goblet cells compose the intestinal mucus. The aims of this study were to determine how they exist in two intestinal mucus layers.The intestinal mucosa was fixed with Carnoy solution and immunostained. Mucus from the loose layer, the firm layer was gently suctioned or scraped, respectively, lysed in SDS sample buffer with or without DTT, then subjected to the western blotting of rTFF3, rIgGFcγBP or rMuc2. The non-reduced or reduced soluble mucus samples in RIPA buffer were co-immunoprecipitated to investigate their possible interactions. Polyclonal antibodies for rTFF3, the rIgGFcγBP C-terminal domain and the rMuc2 C-terminal domain confirmed their localization in the mucus layer and in the mucus collected from the rat intestinal loose layer or firm layer in both western blot and immunoprecipitation experiments. A complex of rTFF3, which was approximately 250 kDa, and a monomer of 6 kDa were present in both layers of the intestinal mucus; rIgGFcγBP was present in the complex (250-280 kDa under non-reducing conditions, but shifted to 164 kDa under reducing conditions in both of the layers. rMuc2 was found mainly in a complex of 214-270 kDa under non-reducing conditions, but it shifted to 140 kDa under reducing conditions. The co-immunoprecipitation experiments showed that binding occurs among rTFF3, rIgGFcγBP and rMuc2 in the RIPA buffer soluble intestinal mucus. Blocking the covalent interaction by 100 mM DTT in the RIPA buffer soluble intestinal mucus disassociated their binding.Rat goblet cell-secreted TFF3, IgGFcγBP and Muc2, existing in the two intestinal mucus layers, are bound together by covalent interactions in the soluble fraction of intestinal mucus and form heteropolymers to be one of the biochemical mechanisms of composing the net-like structure of mucus.

Benchmark Calculations of Noncovalent Interactions of Halogenated Molecules

Czech Academy of Sciences Publication Activity Database

Řezáč, Jan; Riley, Kevin Eugene; Hobza, Pavel

2012-01-01

Roč. 8, č. 11 (2012), s. 4285-4292 ISSN 1549-9618 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : halogenated molecules * noncovalent interactions * benchmark calculations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.389, year: 2012

Polar Flattening and the Strength of Halogen Bonding

Czech Academy of Sciences Publication Activity Database

Sedlák, Robert; Kolář, Michal H.; Hobza, Pavel

2015-01-01

Roč. 11, č. 10 (2015), s. 4727-4732 ISSN 1549-9618 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : density functional theory * interaction energies * halogen bonding Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.301, year: 2015

The Effect of Intermolecular Halogen Bond on 19F DNP Enhancement in 1, 4-Diiodotetrafluorobenzene/4-OH-TEMPO Supramolecular Assembly

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GAO Shan

2017-12-01

Full Text Available Halogen bond, as hydrogen bond, is a non-covalent bond. Dynamic nuclear polarization (DNP technique has been used previously to study hydrogen bonds-mediated intermolecular interactions. However, no study has been carried out so far to study the halogen bond-mediated intermolecular interactions with DNP. In this work, 19F DNP polarization efficiency of the halogen bonds existing in supramolecular assembling by 4-OH-TEMPO and 1,4-diiodotetrafluorobenzene (DITFB was studied on a home-made DNP system. The formation of intermolecular halogen bonds appeared to increase 19F DNP polarization efficiency, suggesting that the spin-spin interactions among electrons were weakened by the halogen bonds, resulting in an increased T2e and a larger saturation factor.

Isomorphism of 2-methylnaphthalene and 2-halonaphthalenes as a revealer of a special interaction between methyl and halogen

Science.gov (United States)

Calvet, T.; Cuevas-Diarte, M. A.; Haget, Y.; Mondieig, D.; Kok, I. C.; Verdonk, M. L.; Van Miltenburg, J. C.; Oonk, H. A. J.

1999-03-01

The systems 2-methylnaphthalene+2-chloronaphthalene and 2-methylnaphthalene+2-bromonaphthalene belong to the exceptional group of binary systems where the formation of mixed crystals goes together with a solid-liquid phase diagram with a maximum. For these systems a thermodynamic analysis is presented which is based on new phase diagram and thermochemical data. The excess Gibbs energies, excess enthalpies, and excess entropies of the mixed crystalline state all are negative. These properties correspond to a net attraction between methyl and substituted halogen. Additional evidence of such an attraction is given by the outcome of a statistical search on intermolecular contacts, in the crystalline state of pure substances, among methyl+halogen, halogen+halogen, and methyl+methyl.

Methods for improved growth of group III nitride buffer layers

Science.gov (United States)

Melnik, Yurity; Chen, Lu; Kojiri, Hidehiro

2014-07-15

Methods are disclosed for growing high crystal quality group III-nitride epitaxial layers with advanced multiple buffer layer techniques. In an embodiment, a method includes forming group III-nitride buffer layers that contain aluminum on suitable substrate in a processing chamber of a hydride vapor phase epitaxy processing system. A hydrogen halide or halogen gas is flowing into the growth zone during deposition of buffer layers to suppress homogeneous particle formation. Some combinations of low temperature buffers that contain aluminum (e.g., AlN, AlGaN) and high temperature buffers that contain aluminum (e.g., AlN, AlGaN) may be used to improve crystal quality and morphology of subsequently grown group III-nitride epitaxial layers. The buffer may be deposited on the substrate, or on the surface of another buffer. The additional buffer layers may be added as interlayers in group III-nitride layers (e.g., GaN, AlGaN, AlN).

A systematic structural study of halogen bonding versus hydrogen bonding within competitive supramolecular systems

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Christer B. Aakeröy

2015-09-01

Full Text Available As halogen bonds gain prevalence in supramolecular synthesis and materials chemistry, it has become necessary to examine more closely how such interactions compete with or complement hydrogen bonds whenever both are present within the same system. As hydrogen and halogen bonds have several fundamental features in common, it is often difficult to predict which will be the primary interaction in a supramolecular system, especially as they have comparable strength and geometric requirements. To address this challenge, a series of molecules containing both hydrogen- and halogen-bond donors were co-crystallized with various monotopic, ditopic symmetric and ditopic asymmetric acceptor molecules. The outcome of each reaction was examined using IR spectroscopy and, whenever possible, single-crystal X-ray diffraction. 24 crystal structures were obtained and subsequently analyzed, and the synthon preferences of the competing hydrogen- and halogen-bond donors were rationalized against a background of calculated molecular electrostatic potential values. It has been shown that readily accessible electrostatic potentials can offer useful practical guidelines for predicting the most likely primary synthons in these co-crystals as long as the potential differences are weighted appropriately.

Emission of Volatile OrganoHalogens by Southern African Solar Salt Works

Science.gov (United States)

Kotte, Karsten; Weissflog, Ludwig; Lange, Christian Albert; Huber, Stefan; Pienaar, Jacobus J.

2010-05-01

Volatile organic compounds containing halogens - especially chlorine - have been considered for a long time of industrial origin only, and it was assumed that the production and emission of these compounds can easily be controlled by humans in case they will cause a threat for life on Earth. Since the middle of the 80ies of the last century it became clear that the biologically active organohalogens isolated by chemists are purposefully produced by nature as antibiotics or as antifeedant etc. To date more than 3800 organohalogens are known to be naturally produced by bio-geochemical processes. The global budgets of many such species are poorly understood and only now with the emergence of better analytical techniques being discovered. For example the compound chloromethane nature's production (5 GT) outdates the anthropogenic production (50 KT) by a factor of 100. Thus organohalogens are an interesting recent case in point since they can influence the ozone budget of the boundary layer, play a role in the production of aerosols and the climate change discussion. An intriguing observation is that most of the atmospheric CH3Cl and CH3Br are of terrestrial rather than of marine origin and that a number of halogenated small organic molecules are produced in soils. The high concentrations of halides in salt soils point to a possibly higher importance of natural halogenation processes as a source of volatile organohalogens. Terrestrial biota, such as fungi, plants, animals and insects, as well as marine algea, bacteria and archaea are known or suspected to be de-novo producers of volatile organohalogens. In recent years we revealed the possibility for VOX to form actively in water and bottom sediments of hyper-saline environments in the course of studying aridization processes during climatic warming. Due to the nature of their production process solar salt works, as to be found along-side the Southern African coast line but also upcountry, combine a variety of semi- and

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15-December 31, 1984

International Nuclear Information System (INIS)

1985-01-01

Energetic halogen atoms or ions, activated by various nuclear transformations are studied in gas, high pressure and condensed phase saturated and unsaturated hydrocarbons, halomethanes, and liquid and solid aqueous solutions of biomolecular and organic solutes in order to understand better the mechanisms and dynamics of high energy monovalent species. The experimental program and its goals remain the same, consisting of four interrelated areas: (1) The stereochemistry of energetic 18 F, /sup 34m/Cl, and 38 Cl substitution reactions with chiral molecules in the gas and condensed phase is studied. (2) The gas to condensed state transition in halogen high energy chemistry, involving energetic chlorine, bromine, and iodine reactions in halomethanes, saturated and unsaturated hydrocarbons and aqueous solutions of biomolecules and alkyl halides is being investigated in more detail. Current attention is given to defining the nature of the enhancement yields in the condensed phase. Specifically, energetic halogen reactions in liquid and frozen aqueous solutions or organic and biomolecular solutes are studied. (3) Reactions of bromine and iodine activated by isomeric transition with halogenated biomolecular and organic solutes in liquid and frozen aqueous solutions are being studied in an attempt to learn more about the activation events in the condensed phase. (4) The applications of hot chemistry techniques and theory to neutron activation analysis of biological systems are being continued. Current attention is given to developing procedures for trace molecular determinations in biological systems. The applications of hot halogen atoms as site indicators in liquid and frozen aqueous solutions of halogenated bases and nucleosides are currently being developed. 14 references

Global impacts of tropospheric halogens (Cl, Br, I on oxidants and composition in GEOS-Chem

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T. Sherwen

2016-09-01

Full Text Available We present a simulation of the global present-day composition of the troposphere which includes the chemistry of halogens (Cl, Br, I. Building on previous work within the GEOS-Chem model we include emissions of inorganic iodine from the oceans, anthropogenic and biogenic sources of halogenated gases, gas phase chemistry, and a parameterised approach to heterogeneous halogen chemistry. Consistent with Schmidt et al. (2016 we do not include sea-salt debromination. Observations of halogen radicals (BrO, IO are sparse but the model has some skill in reproducing these. Modelled IO shows both high and low biases when compared to different datasets, but BrO concentrations appear to be modelled low. Comparisons to the very sparse observations dataset of reactive Cl species suggest the model represents a lower limit of the impacts of these species, likely due to underestimates in emissions and therefore burdens. Inclusion of Cl, Br, and I results in a general improvement in simulation of ozone (O3 concentrations, except in polar regions where the model now underestimates O3 concentrations. Halogen chemistry reduces the global tropospheric O3 burden by 18.6 %, with the O3 lifetime reducing from 26 to 22 days. Global mean OH concentrations of 1.28  ×  106 molecules cm−3 are 8.2 % lower than in a simulation without halogens, leading to an increase in the CH4 lifetime (10.8 % due to OH oxidation from 7.47 to 8.28 years. Oxidation of CH4 by Cl is small (∼  2 % but Cl oxidation of other VOCs (ethane, acetone, and propane can be significant (∼  15–27 %. Oxidation of VOCs by Br is smaller, representing 3.9 % of the loss of acetaldehyde and 0.9 % of the loss of formaldehyde.

Thermodynamics parameters for binding of halogenated benzotriazole inhibitors of human protein kinase CK2α.

Science.gov (United States)

Winiewska, Maria; Kucińska, Katarzyna; Makowska, Małgorzata; Poznański, Jarosław; Shugar, David

2015-10-01

The interaction of human CK2α (hCK2α) with nine halogenated benzotriazoles, TBBt and its analogues representing all possible patterns of halogenation on the benzene ring of benzotriazole, was studied by biophysical methods. Thermal stability of protein-ligand complexes, monitored by calorimetric (DSC) and optical (DSF) methods, showed that the increase in the mid-point temperature for unfolding of protein-ligand complexes (i.e. potency of ligand binding to hCK2α) follow the inhibitory activities determined by biochemical assays. The dissociation constant for the ATP-hCK2α complex was estimated with the aid of microscale thermophoresis (MST) as 4.3±1.8 μM, and MST-derived dissociation constants determined for halogenated benzotriazoles, when converted according to known ATP concentrations, perfectly reconstruct IC50 values determined by the biochemical assays. Ligand-dependent quenching of tyrosine fluorescence, together with molecular modeling and DSC-derived heats of unfolding, support the hypothesis that halogenated benzotriazoles bind in at least two alternative orientations, and those that are efficient hCK2α inhibitors bind in the orientation which TBBt adopts in its complex with maize CK2α. DSC-derived apparent heat for ligand binding (ΔΔHbind) is driven by intermolecular electrostatic interactions between Lys68 and the triazole ring of the ligand, as indicated by a good correlation between ΔΔHbind and ligand pKa. Overall results, additionally supported by molecular modeling, confirm that a balance of hydrophobic and electrostatic interactions contribute predominantly (~40 kJ/mol), relative to possible intermolecular halogen/hydrogen bonding (less than 10 kJ/mol), in binding of halogenated benzotriazoles to the ATP-binding site of hCK2α. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases. Copyright © 2015 Elsevier B.V. All rights reserved.

Radiolysis of aqueous solutions of nucleosides halogenated at the sugar moiety

Energy Technology Data Exchange (ETDEWEB)

Hissung, A; Isildar, M; von Sonntag, C [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany, F.R.). Inst. fuer Strahlenforschung; Witzel, H [Biochemisches Institut der Westfaelischen Wilhelms-Universitaet, Muenster, West Germany

1981-02-01

The pulse radiolysis of aqueous solutions of nucleosides halogenated at the sugar moiety (2'-bromo-2'-deoxyuridine 4, 3'-deoxy-3'-iodothymidine 5, 5'-deoxy-5'-iodouridine 6) has been studied. G(Hal) were determined by conductometry varying the experimental conditions (pH, saturation with Ar, N/sub 2/O or air, addition of t-butanol). The results indicate that solvated electrons both add to the nucleobases and eliminate halogen ions from the halogenated sugar moiety. In the case of 4(and possibly of 5) the radical anion of the base transfers (k approximately 10/sup 5/s/sup -1/) an electron to the sugar-bound halogen atom thus cleaving the C-Hal bond. In competition with this reaction there is a protonation of the radical anion of the base by protons and by water. For the latter reaction constant of k = 5 x 10/sup 3/ M/sup -1/s/sup -1/ was estimated. Compound 4 has also been investigated by product analysis after 60-Co-..gamma..-irradiation. In aerated solutions erythrose is formed with a G-value of 0.12. Its precursor radical is the 2'-radical generated from 4 by dissociative electron capture which reacts with O/sub 2/ to the corresponding peroxyl radical. Erythrose is formed after a sequence of reactions, one of which involves the scission of the C-1'-C-2'bond. Under this condition G(HBr) as measured by pulse radiolysis is 0.8. Thus erythrose is formed in 15 per cent yield with respect to its precursor radical. This result is of importance in assessing the precursor radical of a similar product observed in irradiated DNA.

Radiolysis of aqueous solutions of nucleosides halogenated at the sugar moiety

International Nuclear Information System (INIS)

Hissung, A.; Isildar, M.; Sonntag, C. von; Witzel, H.

1981-01-01

The pulse radiolysis of aqueous solutions of nucleosides halogenated at the sugar moiety (2'-bromo-2'-deoxyuridine 4, 3'-deoxy-3'-iodothymidine 5, 5'-deoxy-5'-iodouridine 6) has been studied. G(Hal) were determined by conductometry varying the experimental conditions (pH, saturation with Ar, N 2 O or air, addition of t-butanol). The results indicate that solvated electrons both add to the nucleobases and eliminate halogen ions from the halogenated sugar moiety. In the case of 4(and possibly of 5) the radical anion of the base transfers (k approximately 10 5 s -1 ) an electron to the sugar-bound halogen atom thus cleaving the C-Hal bond. In competition with this reaction there is a protonation of the radical anion of the base by protons and by water. For the latter reaction constant of k = 5 x 10 3 M -1 s -1 was estimated. Compound 4 has also been investigated by product analysis after 60-Co-γ-irradiation. In aerated solutions erythrose is formed with a G-value of 0.12. Its precursor radical is the 2'-radical generated from 4 by dissociative electron capture which reacts with O 2 to the corresponding peroxyl radical. Erythrose is formed after a sequence of reactions, one of which involves the scission of the C-1'-C-2'bond. Under this condition G(HBr) as measured by pulse radiolysis is 0.8. Thus erythrose is formed in 15 per cent yield with respect to its precursor radical. This result is of importance in assessing the precursor radical of a similar product observed in irradiated DNA. (author)

Halogen bond preferences of thiocyanate ligand coordinated to Ru(II) via sulphur atom

Science.gov (United States)

Ding, Xin; Tuikka, Matti; Hirva, Pipsa; Haukka, Matti

2017-09-01

Halogen bonding between [Ru(bpy)(CO)2(S-SCN)2] (bpy = 2,2'-bipyridine), I2 was studied by co-crystallising the metal compound and diiodine from dichloromethane. The only observed crystalline product was found to be [Ru(bpy)(CO)2(S-SCN)2]ṡI2 with only one NCSṡṡṡI2 halogen bond between I2 and the metal coordinated S atom of one of the thiocyanate ligand. The dangling nitrogen atoms were not involved in halogen bonding. However, computational analysis suggests that there are no major energetic differences between the NCSṡṡṡI2 and SCNṡṡṡI2 bonding modes. The reason for the observed NCSṡṡṡI2 mode lies most probably in the more favourable packing effects rather than energetic preferences between NCSṡṡṡI2 and SCNṡṡṡI2 contacts.

Photofragmentation spectra of halogenated methanes in the VUV photon energy range

Energy Technology Data Exchange (ETDEWEB)

Cartoni, Antonella, E-mail: antonella.cartoni@uniroma1.it [Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, Roma 00185 (Italy); Bolognesi, Paola; Fainelli, Ettore; Avaldi, Lorenzo [CNR-IMIP, Area della Ricerca di Roma 1, Monterotondo Scalo (Rm) 00015 (Italy)

2014-05-14

In this paper an investigation of the photofragmentation of dihalomethanes CH{sub 2}X{sub 2} (X = F, Cl, Br, I) and chlorinated methanes (CH{sub n}Cl{sub 4−n} with n = 0–3) with VUV helium, neon, and argon discharge lamps is reported and the role played by the different halogen atoms is discussed. Halogenated methanes are a class of molecules used in several fields of chemistry and the study of their physical and chemical proprieties is of fundamental interest. In particular their photodissociation and photoionization are of great importance since the decomposition of these compounds in the atmosphere strongly affects the environment. The results of the present work show that the halogen-loss is the predominant fragmentation channel for these molecules in the VUV photon energy range and confirm their role as reservoir of chlorine, bromine, and iodine atoms in the atmosphere. Moreover, the results highlight the peculiar feature of CH{sub 2}F{sub 2} as a source of both fluorine and hydrogen atoms and the characteristic formation of I{sub 2}{sup +} and CH{sub 2}{sup +} ions from the photofragmentation of the CH{sub 2}I{sub 2} molecule.

Mutagenic activity of halogenated propanes and propenes: effect of bromine and chlorine positioning.

Science.gov (United States)

Låg, M; Omichinski, J G; Dybing, E; Nelson, S D; Søderlund, E J

1994-10-01

A series of halogenated propanes and propenes were studied for mutagenic effects in Salmonella typhimurium TA100 in the absence or presence of NADPH plus liver microsomes from phenobarbital-induced rats as an exogenous metabolism system. The cytotoxic and mutagenic effects of the halogenated propane 1,2-dibromo-3-chloropropane (DBCP) has previously been studied in our laboratories. These studies showed that metabolic activation of DBCP was required to exert its detrimental effects. All of the trihalogenated propane analogues were mutagenic when the microsomal activation system was included. The highest mutagenic activity was obtained with 1,2,3-tribromopropane, with approximately 50-fold higher activity than the least mutagenic trihalogenated propane, 1,2,3-trichloropropane. The order of mutagenicity was as follows: 1,2,3-tribromopropane > or = 1,2-dibromo- 3-chloropropane > 1,3-dibromo-2-chloropropane > or = 1,3-dichloro-2-bromopropane > 1-bromo-2,3-dichloropropane > 1,2,3-trichloropropane. Compared to DBCP, the dihalogenated propanes were substantially less mutagenic. Only 1,2-dibromopropane was mutagenic and its mutagenic potential was approximately 1/30 of that of DBCP. In contrast to DBCP, 1,2-dibromopropane showed similar mutagenic activity with and without the addition of an activation system. The halogenated propenes 2,3-dibromopropene and 2-bromo-3-chloropropene were mutagenic to the bacteria both in the absence and presence of the activation system, whereas 2,3-dichloropropene did not show any mutagenic effect. The large differences in mutagenic potential between the various halogenated propanes and propenes are proposed to be due to the formation of different possible proximate and ultimate mutagenic metabolites resulting from the microsomal metabolism of the various halogenated propanes and propenes, and to differences in the rate of formation of the metabolites. Pathways are proposed for the formation of genotoxic metabolites of di- and trihalogenated

Extending Halogen-based Medicinal Chemistry to Proteins: IODO-INSULIN AS A CASE STUDY.

Science.gov (United States)

El Hage, Krystel; Pandyarajan, Vijay; Phillips, Nelson B; Smith, Brian J; Menting, John G; Whittaker, Jonathan; Lawrence, Michael C; Meuwly, Markus; Weiss, Michael A

2016-12-30

Insulin, a protein critical for metabolic homeostasis, provides a classical model for protein design with application to human health. Recent efforts to improve its pharmaceutical formulation demonstrated that iodination of a conserved tyrosine (Tyr B26 ) enhances key properties of a rapid-acting clinical analog. Moreover, the broad utility of halogens in medicinal chemistry has motivated the use of hybrid quantum- and molecular-mechanical methods to study proteins. Here, we (i) undertook quantitative atomistic simulations of 3-[iodo-Tyr B26 ]insulin to predict its structural features, and (ii) tested these predictions by X-ray crystallography. Using an electrostatic model of the modified aromatic ring based on quantum chemistry, the calculations suggested that the analog, as a dimer and hexamer, exhibits subtle differences in aromatic-aromatic interactions at the dimer interface. Aromatic rings (Tyr B16 , Phe B24 , Phe B25 , 3-I-Tyr B26 , and their symmetry-related mates) at this interface adjust to enable packing of the hydrophobic iodine atoms within the core of each monomer. Strikingly, these features were observed in the crystal structure of a 3-[iodo-Tyr B26 ]insulin analog (determined as an R 6 zinc hexamer). Given that residues B24-B30 detach from the core on receptor binding, the environment of 3-I-Tyr B26 in a receptor complex must differ from that in the free hormone. Based on the recent structure of a "micro-receptor" complex, we predict that 3-I-Tyr B26 engages the receptor via directional halogen bonding and halogen-directed hydrogen bonding as follows: favorable electrostatic interactions exploiting, respectively, the halogen's electron-deficient σ-hole and electronegative equatorial band. Inspired by quantum chemistry and molecular dynamics, such "halogen engineering" promises to extend principles of medicinal chemistry to proteins. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Chiral halogenated Schiff base compounds: green synthesis, anticancer activity and DNA-binding study

Science.gov (United States)

Ariyaeifar, Mahnaz; Amiri Rudbari, Hadi; Sahihi, Mehdi; Kazemi, Zahra; Kajani, Abolghasem Abbasi; Zali-Boeini, Hassan; Kordestani, Nazanin; Bruno, Giuseppe; Gharaghani, Sajjad

2018-06-01

Eight enantiomerically pure halogenated Schiff base compounds were synthesized by reaction of halogenated salicylaldehydes with 3-Amino-1,2-propanediol (R or S) in water as green solvent at ambient temperature. All compounds were characterized by elemental analyses, NMR (1H and 13C), circular dichroism (CD) and FT-IR spectroscopy. FS-DNA binding studies of these compounds carried out by fluorescence quenching and UV-vis spectroscopy. The obtained results revealed that the ligands bind to DNA as: (Rsbnd ClBr) > (Rsbnd Cl2) > (Rsbnd Br2) > (Rsbnd I2) and (Ssbnd ClBr) > (Ssbnd Cl2) > (Ssbnd Br2) > (Ssbnd I2), indicating the effect of halogen on binding constant. In addition, DNA-binding constant of the Ssbnd and R-enantiomers are different from each other. The ligands can form halogen bonds with DNA that were confirmed by molecular docking. This method was also measured the bond distances and bond angles. The study of obtained data can have concluded that binding affinity of the ligands to DNA depends on strength of halogen bonds. The potential anticancer activity of ligands were also evaluated on MCF-7 and HeLa cancer cell lines by using MTT assay. The results showed that the anticancer activity and FS-DNA interaction is significantly dependent on the stereoisomers of Schiff base compounds as R-enantiomers displayed significantly higher activity than S-enantiomers. The molecular docking was also used to illustrate the specific DNA-binding of synthesized compounds and groove binding mode of DNA interaction was proposed for them. In addition, molecular docking results indicated that there are three types of bonds (Hsbnd and X-bond and hX-bond) between synthesized compounds and base pairs of DNA.

Detection of halogenated flame retardants in polyurethane foam by particle induced X-ray emission

International Nuclear Information System (INIS)

Maley, Adam M.; Falk, Kyle A.; Hoover, Luke; Earlywine, Elly B.; Seymour, Michael D.; DeYoung, Paul A.; Blum, Arlene; Stapleton, Heather M.; Peaslee, Graham F.

2015-01-01

A novel application of particle-induced X-ray emission (PIXE) has been developed to detect the presence of chlorinated and brominated flame retardant chemicals in polyurethane foams. Traditional Gas Chromatography–Mass Spectrometry (GC–MS) methods for the detection and identification of halogenated flame retardants in foams require extensive sample preparation and data acquisition time. The elemental analysis of the halogens in polyurethane foam performed by PIXE offers the opportunity to identify the presence of halogenated flame retardants in a fraction of the time and sample preparation cost. Through comparative GC–MS and PIXE analysis of 215 foam samples, excellent agreement between the two methods was obtained. These results suggest that PIXE could be an ideal rapid screening method for the presence of chlorinated and brominated flame retardants in polyurethane foams

Detection of halogenated flame retardants in polyurethane foam by particle induced X-ray emission

Energy Technology Data Exchange (ETDEWEB)

Maley, Adam M.; Falk, Kyle A.; Hoover, Luke; Earlywine, Elly B.; Seymour, Michael D. [Department of Chemistry, Hope College, 35 E. 12th Street, Holland, MI 49423 (United States); DeYoung, Paul A. [Department of Physics, Hope College, 27 Graves Place, Holland, MI 49423 (United States); Blum, Arlene [Green Science Policy Institute, Box 5455, Berkeley, CA 94705 (United States); Stapleton, Heather M. [Nicholas School of the Environment, Duke University, LSRC Box 90328, Durham, NC 27708 (United States); Peaslee, Graham F., E-mail: peaslee@hope.edu [Department of Chemistry, Hope College, 35 E. 12th Street, Holland, MI 49423 (United States)

2015-09-01

A novel application of particle-induced X-ray emission (PIXE) has been developed to detect the presence of chlorinated and brominated flame retardant chemicals in polyurethane foams. Traditional Gas Chromatography–Mass Spectrometry (GC–MS) methods for the detection and identification of halogenated flame retardants in foams require extensive sample preparation and data acquisition time. The elemental analysis of the halogens in polyurethane foam performed by PIXE offers the opportunity to identify the presence of halogenated flame retardants in a fraction of the time and sample preparation cost. Through comparative GC–MS and PIXE analysis of 215 foam samples, excellent agreement between the two methods was obtained. These results suggest that PIXE could be an ideal rapid screening method for the presence of chlorinated and brominated flame retardants in polyurethane foams.

Can Halogen Enrichment in Reduced Enstatite Chondrites Provide Clues to Volatile Accretion in the Early Earth?

Science.gov (United States)

Clay, P. L.; Burgess, R.; Busemann, H.; Ruzié, L.; Joachim, B.; Ballentine, C.

2013-12-01

Understanding how the Earth obtained and ultimately retained its volatiles is important for our overall understanding of large scale planetary evolution. Numerous models exist for the heterogeneous accretion of volatiles to early Earth, but accounting for all elements through accretion of typical planetary building blocks (e.g., CI chondrites) is difficult. Proto-planetary collisions resulting in the accretion of volatile-poor material under reducing conditions followed by accretion of volatile-rich material under oxidizing conditions has been suggested in such models [e.g., 1]. The heavy halogens (Cl, Br and I), a group of moderately volatile elements, are excellent tracers of planetary processing due to their low abundance and incompatible nature. Therefore characterizing halogen abundance and distribution in materials that accreted to form the planets, e.g., primitive meteorites, is crucial. One group of primitive meteorites, the enstatite chondrites (EC's), are amongst the most reduced materials in the solar system as evidenced by their unique mineral assemblage. Yet despite forming under ultra-reducing conditions, they are enriched in the moderately volatile elements, such as the halogens. The ECs are of particular interest owing to their oxygen isotopic composition which plots along the terrestrial fractionation line, linking them isotopically to the Earth-Moon system. These samples can thus potentially provide clues on the accretion of moderately volatile element rich material under reducing conditions, such as it may have existed during the early stages of Earth's accretion. Chlorine, Br and I concentrations in ECs were determined through step-heating small neutron-irradiated samples (0.3 to 3.3 mg) and measured by mass spectrometry using the noble gas proxy isotopes 38ArCl/Cl, 80KrBr/Br and 128XeI/I. The EH chondrites are consistently enriched in the heavy halogens (up to 330 ppm Cl, 2290 ppb Br and 180 ppb I), compared to other ordinary and carbonaceous

Evaluation of 10 aliphatic halogenated hydrocarbons in the mouse bone marrow micronucleus test.

Science.gov (United States)

Crebelli, R; Carere, A; Leopardi, P; Conti, L; Fassio, F; Raiteri, F; Barone, D; Ciliutti, P; Cinelli, S; Vericat, J A

1999-03-01

Ten halogenated aliphatic hydrocarbons (carbon tetrachloride, 1-chlorohexane, 2,3-dichlorobutane, 1,2-dichloroethane, 1,2-dichloroethylene, 1,3-dichloropropane, hexachloroethane, 1,1,2-trichloroethane, 1,2,3-trichloropropane and 1,1,3-trichloropropene), previously assayed in genetic assays in fungi, were evaluated in the mouse bone marrow micronucleus test in order to assess their genotoxicity in vivo. All chemicals were administered once i.p. at 40 and 70-80% of their respective LD50 to male and female CD-1 mice, 24 and 48 h before killing. All treatments produced evident clinical symptoms, but no marked depression of bone marrow proliferation. No statistically significant increases in the incidence of micronucleated polychromatic erythrocytes over the control values were observed at any sampling time with any of the 10 halogenated hydrocarbons assayed. The comparison of the results obtained in this study with the findings provided by in vitro micronucleus assays on the same chemicals, reported by other authors, indicate that mouse bone marrow is weakly sensitive to the genotoxic effects induced by halogenated hydrocarbons in other test systems. This suggests that the role of such an assay in carcinogen screening may be questionable for this chemical class. An examination of mouse bone marrow micronucleus test results with the halogenated aliphatic hydrocarbons classified as carcinogens by IARC supports this conclusion.

Copper-catalyzed recycling of halogen activating groups via 1,3-halogen migration.

Science.gov (United States)

Grigg, R David; Van Hoveln, Ryan; Schomaker, Jennifer M

2012-10-03

A Cu(I)-catalyzed 1,3-halogen migration reaction effectively recycles an activating group by transferring bromine or iodine from a sp(2) to a benzylic carbon with concomitant borylation of the Ar-X bond. The resulting benzyl halide can be reacted in the same vessel under a variety of conditions to form an additional carbon-heteroatom bond. Cross-over experiments using an isotopically enriched bromide source support intramolecular transfer of Br. The reaction is postulated to proceed via a Markovnikov hydrocupration of the o-halostyrene, oxidative addition of the resulting Cu(I) complex into the Ar-X bond, reductive elimination of the new sp(3) C-X bond, and final borylation of an Ar-Cu(I) species to turn over the catalytic cycle.

[Near infrared light irradiator using halogen lamp].

Science.gov (United States)

Ide, Yasuo

2012-07-01

The practical electric light bulb was invented by Thomas Alva Edison in 1879. Halogen lamp is the toughest and brightest electric light bulb. With light filter, it is used as a source of near infrared light. Super Lizer and Alphabeam are made as near infrared light irradiator using halogen lamp. The light emmited by Super Lizer is linear polarized near infrared light. The wave length is from 600 to 1,600 nm and strongest at about 1,000 nm. Concerning Super Lizer, there is evidence of analgesic effects and normalization of the sympathetic nervous system. Super Lizer has four types of probes. SG type is used for stellate ganglion irradiation. B type is used for narrow area irradiation. C and D types are for broad area irradiation. The output of Alphabeam is not polarized. The wave length is from 700 to 1,600 nm and the strongest length is about 1,000nm. Standard attachment is used for spot irradiation. Small attachment is used for stellate ganglion irradiation. Wide attachment is used for broad area irradiation. The effects of Alphabeam are thought to be similar to that of Super Lizer.

Terminal structure

Science.gov (United States)

Schmidt, Frank [Langenhagen, DE; Allais, Arnaud [Hannover, DE; Mirebeau, Pierre [Villebon sur Yvette, FR; Ganhungu, Francois [Vieux-Reng, FR; Lallouet, Nicolas [Saint Martin Boulogne, FR

2009-10-20

A terminal structure (2) for a superconducting cable (1) is described. It consists of a conductor (2a) and an insulator (2b) that surrounds the conductor (2a), wherein the superconducting cable (1) has a core with a superconducting conductor (5) and a layer of insulation that surrounds the conductor (5), and wherein the core is arranged in such a way that it can move longitudinally in a cryostat. The conductor (2a) of the terminal structure (2) is electrically connected with the superconducting conductor (5) or with a normal conductor (6) that is connected with the superconducting conductor (5) by means of a tubular part (7) made of an electrically conductive material, wherein the superconducting conductor (5) or the normal conductor (6) can slide in the part (7) in the direction of the superconductor.

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.

Molecular Engineering of Non-Halogenated Solution-Processable Bithiazole based Electron Transport Polymeric Semiconductors

KAUST Repository

Fu, Boyi

2015-04-01

The electron deficiency and trans planar conformation of bithiazole is potentially beneficial for the electron transport performance of organic semiconductors. However, the incorporation of bithiazole into polymers through a facile synthetic strategy remains a challenge. Herein, 2,2’-bithiazole was synthesized in one step and copolymerized with dithienyldiketopyrrolopyrrole to afford poly(dithienyldiketopyrrolopyrrole-bithiazole), PDBTz. PDBTz exhibited electron mobility reaching 0.3 cm2V-1s-1 in organic field-effect transistor (OFET) configuration; this contrasts with a recently discussed isoelectronic conjugated polymer comprising an electron rich bithiophene and dithienyldiketopyrrolopyrrole, which displays merely hole transport characteristics. This inversion of charge carrier transport characteristics confirms the significant potential for bithiazole in the development of electron transport semiconducting materials. Branched 5-decylheptacyl side chains were incorporated into PDBTz to enhance polymer solubility, particularly in non-halogenated, more environmentally compatible solvents. PDBTz cast from a range of non-halogenated solvents exhibited film morphologies and field-effect electron mobility similar to those cast from halogenated solvents.

Molecular Engineering of Non-Halogenated Solution-Processable Bithiazole based Electron Transport Polymeric Semiconductors

KAUST Repository

Fu, Boyi; Wang, Cheng-Yin; Rose, Bradley Daniel; Jiang, Yundi; Chang, Mincheol; Chu, Ping-Hsun; Yuan, Zhibo; Fuentes-Hernandez, Canek; Bernard, Kippelen; Bredas, Jean-Luc; Collard, David M.; Reichmanis, Elsa

2015-01-01

The electron deficiency and trans planar conformation of bithiazole is potentially beneficial for the electron transport performance of organic semiconductors. However, the incorporation of bithiazole into polymers through a facile synthetic strategy remains a challenge. Herein, 2,2’-bithiazole was synthesized in one step and copolymerized with dithienyldiketopyrrolopyrrole to afford poly(dithienyldiketopyrrolopyrrole-bithiazole), PDBTz. PDBTz exhibited electron mobility reaching 0.3 cm2V-1s-1 in organic field-effect transistor (OFET) configuration; this contrasts with a recently discussed isoelectronic conjugated polymer comprising an electron rich bithiophene and dithienyldiketopyrrolopyrrole, which displays merely hole transport characteristics. This inversion of charge carrier transport characteristics confirms the significant potential for bithiazole in the development of electron transport semiconducting materials. Branched 5-decylheptacyl side chains were incorporated into PDBTz to enhance polymer solubility, particularly in non-halogenated, more environmentally compatible solvents. PDBTz cast from a range of non-halogenated solvents exhibited film morphologies and field-effect electron mobility similar to those cast from halogenated solvents.

Optimization of the GaAs et GaAs/Si annealing using halogen lamp flashes

International Nuclear Information System (INIS)

Blanck, H.

1989-01-01

The aim of the work is to check whether the flash annealing of GaAs and GaAs/Si, using halogen lamps, allows an improvement in the results obtained by usual methods. The electrical activation, defects behavior and results uniformity are studied. The results on the activation and diffusion of implanted impurities are shown to be equivalent to those obtained with classical annealing methods. However, residual impurities (or defects) diffusion phenomena are restrained by the flash annealing technique. The Hall effect cartographic measurements showed an improvement of the uniformity of the implanted coating surface resistance. Flash annealing is a suitable method for the Si activation in GaAs. It allows an improvement of the GaAs results obtained with standard techniques, as well as the formation, by means of ion implantation, of active zones in the GaAs/Si layers [fr

Mercury and halogens in coal: Chapter 2

Science.gov (United States)

Kolker, Allan; Quick, Jeffrey C.; Granite, Evan J.; Pennline, Henry W.; Senior, Constance L.

2014-01-01

Apart from mercury itself, coal rank and halogen content are among the most important factors inherent in coal that determine the proportion of mercury captured by conventional controls during coal combustion. This chapter reviews how mercury in coal occurs, gives available concentration data for mercury in U.S. and international commercial coals, and provides an overview of the natural variation in halogens that influence mercury capture. Three databases, the U.S. Geological Survey coal quality (USGS COALQUAL) database for in-ground coals, and the 1999 and 2010 U.S. Environmental Protection Agency (EPA) Information Collection Request (ICR) databases for coals delivered to power stations, provide extensive results for mercury and other parameters that are compared in this chapter. In addition to the United States, detailed characterization of mercury is available on a nationwide basis for China, whose mean values in recent compilations are very similar to the United States in-ground mean of 0.17 ppm mercury. Available data for the next five largest producers (India, Australia, South Africa, the Russian Federation, and Indonesia) are more limited and with the possible exceptions of Australia and the Russian Federation, do not allow nationwide means for mercury in coal to be calculated. Chlorine in coal varies as a function of rank and correspondingly, depth of burial. As discussed elsewhere in this volume, on a proportional basis, bromine is more effective than chlorine in promoting mercury oxidation in flue gas and capture by conventional controls. The ratio of bromine to chlorine in coal is indicative of the proportion of halogens present in formation waters within a coal basin. This ratio is relatively constant except in coals that have interacted with deep-basin brines that have reached halite saturation, enriching residual fluids in bromine. Results presented here help optimize mercury capture by conventional controls and provide a starting point for

Halogenated hydrocarbons - an environmental problem

Energy Technology Data Exchange (ETDEWEB)

Schoeler, H F; Thofern, E

1984-01-01

The paper provides a survey of the incidence of highly volatile halogenated hydrocarbons in ground, surface and drinking water as well as in the snows of Western Germany. Almost the entire production of chlorinated solvents is released into the environment. The absorption media are mostly soil, water and atmosphere. Whereas in the atmosphere elimination reactions take place, solvents that have passed the soil get into the ground water owing to their persistence and can cause considerable pollutions of drinking water. Moreover haloforms may occur in drinking water, which are produced during chlorine disinfection of pre-treated water.

Characterization of halogenated DBPs and identification of new DBPs trihalomethanols in chlorine dioxide treated drinking water with multiple extractions.

Science.gov (United States)

Han, Jiarui; Zhang, Xiangru; Liu, Jiaqi; Zhu, Xiaohu; Gong, Tingting

2017-08-01

Chlorine dioxide (ClO 2 ) is a widely used alternative disinfectant due to its high biocidal efficiency and low-level formation of trihalomethanes and haloacetic acids. A major portion of total organic halogen (TOX), a collective parameter for all halogenated DBPs, formed in ClO 2 -treated drinking water is still unknown. A commonly used pretreatment method for analyzing halogenated DBPs in drinking water is one-time liquid-liquid extraction (LLE), which may lead to a substantial loss of DBPs prior to analysis. In this study, characterization and identification of polar halogenated DBPs in a ClO 2 -treated drinking water sample were conducted by pretreating the sample with multiple extractions. Compared to one-time LLE, the combined four-time LLEs improved the recovery of TOX by 2.3 times. The developmental toxicity of the drinking water sample pretreated with the combined four-time LLEs was 1.67 times higher than that pretreated with one-time LLE. With the aid of ultra-performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry, a new group of polar halogenated DBPs, trihalomethanols, were detected in the drinking water sample pretreated with multiple extractions; two of them, trichloromethanol and bromodichloromethanol, were identified with synthesized standard compounds. Moreover, these trihalomethanols were found to be the transformation products of trihalomethanes formed during ClO 2 disinfection. The results indicate that multiple LLEs can significantly improve extraction efficiencies of polar halogenated DBPs and is a better pretreatment method for characterizing and identifying new polar halogenated DBPs in drinking water. Copyright © 2017. Published by Elsevier B.V.

40 CFR 63.2465 - What requirements must I meet for process vents that emit hydrogen halide and halogen HAP or HAP...

Science.gov (United States)

2010-07-01

... process vents that emit hydrogen halide and halogen HAP or HAP metals? 63.2465 Section 63.2465 Protection... and halogen HAP or HAP metals? (a) You must meet each emission limit in Table 3 to this subpart that... section. (b) If any process vents within a process emit hydrogen halide and halogen HAP, you must...

Compound deterioration properties of non-halogen flame-resisting cables

International Nuclear Information System (INIS)

Yamamoto, Yasuaki; Yagyu, Hideki; Onishi, Takao; Kamiharako, Shinji

1984-01-01

Conventional flame-resisting cables release harmful gas such as hydrogen chloride and smoke on burning. To improve this disadvantage, the cables for nuclear power plants using new non-halogen flame-resisting insulating material have been developed. In this experiment, the non-halogen flame-resisting cables were subjected to the environmental test with varying test conditions. The test conditions included the order of exposure (heat treatment, γ-ray irradiation and steam exposure) and dose rate. After the environmental test, the mechanical and electrical properties of the samples were measured. In all test conditions, the samples did not crack in bending, and withstood the bending and withstand-voltage in-water test. The tensile strength and a.c. breakdown voltage did not change, and were stable. The elongation decreased greatly, but maintained the value of about 100 %, and the volumetric resistivity decreased by only one figure. It was confirmed that these cables were able to withstand various environmental tests. (Yoshitake, I.)

Determination of halogen content in glass for assessment of melter decontamination factors

International Nuclear Information System (INIS)

Goles, R.W.

1996-03-01

Melter decontamination factor (DF) values for the halogens (fluorine, chlorine, and iodine) are important to the Hanford Waste Vitrification Plant (HWVP) process because of the potential influence of DF on secondary-waste recycle strategies (fluorine and chlorine) as well as its impact on off-gas emissions (iodine). This study directly establishes the concentrations of halides-in HWVP simulated reference glasses rather than relying on indirect off-gas data. For fluorine and chlorine, pyrohydrolysis coupled with halide (ion chromatographic) detection has proven to be a useful analytical approach suitable for glass matrices, sensitive enough for the range of halogens encountered, and compatible with remote process support applications. Results obtained from pyrohydrolytic analysis of pilot-scale ceramic melter (PSCM) -22 and -23 glasses indicate that the processing behavior of fluorine and chlorine is quite variable even under similar processing conditions. Specifically, PSCM-23 glass exhibited a ∼90% halogen (F and Cl) retention efficiency, while only 20% was incorporated in PSCM-22 glass. These two sets of very dissimilar test results clearly do not form a sufficient basis for establishing design DF values for fluorine and chlorine. Because the present data do not provide any new halogen volatility information, but instead reconfirm the validity of previously obtained offgas derived values, melter DF values of 4, 2, and 1 for fluorine, chlorine, and iodine, respectively, are recommended for adoption; these values were conservatively established by a team of responsible engineers at Westinghouse Hanford Company (WHC) and Pacific Northwest Laboratory (PNL) on the basis of average behavior for many comparable melter tests. In the absence of further HWVP process data, these average melter DFs are the best values currently available

Composes inter-halogenes sous pression: etude des transformations structurales dans le monobromure d'iode sous forme dense

Science.gov (United States)

Bouchard, Alexandre

La famille des composes halogenes et inter-halogenes representent des solides moleculaires adoptant des phases denses communes avec des solides moleculaires diatomiques comme l'azote et l'hydrogene. Parmi les transformations structurales et electroniques induites sous haute pression et observees dans ces solides, on note, entre autres, la dissociation moleculaire et la metallisation. De plus, l'etude des phases denses de l'iode a permis recemment l'observation d'une structure cristalline possedant une modulation dite incommensurable, c'est-a-dire une modulation possedant une periodicite differente de celle de la structure cristalline, jetant ainsi une lumiere nouvelle sur le processus de dissociation moleculaire dans les solides halogenes. Dans ce memoire, on propose d'etudier les changements structuraux dans monobromure d'iode (IBr), un compose inter-halogene possedant des proprietes structurales semblables a celles de deux composes halogenes, soit l'iode (I 2) et le brome (Br2) sous leur forme solide. Des experiences de diffraction des rayons X de poudres en utilisant un rayonnement synchrotron ont ete realisees a temperature ambiante sur l'IBr en variant la pression jusqu'aux environs de 60 GPa. La nature chimique particuliere du compose IBr a necessite la mise au point de techniques de chargement d'echantillon destinees a preserver l'integrite chimique de la substance utilisee. On rapporte egalement l'observation d'une phase de l'IBr presentant une modulation incommensurable. Les phases observees dans l'IBr permettent d'etablir des paralleles avec les phases denses rapportees dans I2 et Br2 par le biais d'un modele phenomenologique decrivant la sequence structurale des solides halogenes sous forme condensee.

Development of halogen-free flame-retardant cable for nuclear power plant. 2

International Nuclear Information System (INIS)

Matsumoto, Tetsuo; Kimura, Hitoshi; Ishii, Nobuhisa

1997-01-01

Halogen-free flame-retardant cables were developed for PWR nuclear power stations. It was confirmed that the developed cables possess flame retardant property, corrosion resistance, low toxicity and low smoke generation, and withstand the normal operation in the environment in PWR containment vessels for 60 years and loss of coolant accident. In the advancement of LWR technology, it is important to improve the reliability of machinery and equipment, to extend the period of continuous operation, to optimize the operation cycle and to improve the maintenance of plants. By improving halogen-free flame-retardant material and applying it to the cables for nuclear power stations, it can contribute to the above purposes. The required characteristics of these cables are explained, and the targets of development are power cables, control cables, instrumentation cables and insulated wires which do not contain halogen. The basic material is polyolefin, in which flame retardant magnesium hydroxide and the agent for improving radiation resistance are mixed. The corrosive property and toxicity of gases, smoke generation and the prevention of spread of flame when the cables burn and the durability in environment were evaluated. (K.I.)

Development of an enzymatic fiber-optic biosensor for detection of halogenated hydrocarbons

Energy Technology Data Exchange (ETDEWEB)

Bidmanova, Sarka; Chaloupkova, Radka; Damborsky, Jiri; Prokop, Zbynek [Masaryk University, Loschmidt Laboratories, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, Faculty of Science, Brno (Czech Republic)

2010-11-15

An enzyme-based biosensor was developed by co-immobilization of purified enzyme haloalkane dehalogenase (EC 3.8.1.5) and a fluorescence pH indicator on the tip of an optical fiber. Haloalkane dehalogenase catalyzes hydrolytic dehalogenation of halogenated aliphatic hydrocarbons, which is accompanied by a pH change influencing the fluorescence of the indicator. The pH sensitivity of several fluorescent dyes was evaluated. The selected indicator 5(6)-carboxyfluorescein was conjugated with bovine serum albumin and its reaction was tested under different immobilization conditions. The biosensor was prepared by cross-linking of the conjugate in tandem with haloalkane dehalogenase using glutaraldehyde vapor. The biosensor, stored for 24 h in 50 mM phosphate buffer (pH 7.5) prior to measurement, was used after 15 min of equilibration, the halogenated compound was added, and the response was monitored for 30 min. Calibration of the biosensor with 1,2-dibromoethane and 3-chloro-2-(chloromethyl)-1-propene showed an excellent linear dependence, with detection limits of 0.133 and 0.014 mM, respectively. This biosensor provides a new tool for continuous in situ monitoring of halogenated environmental pollutants. (orig.)

Quantum Chemical Examination of the Sequential Halogen Incorporation Scheme for the Modeling of Speciation of I/Br/Cl-Containing Trihalomethanes.

Science.gov (United States)

Zhang, Chenyang; Li, Maodong; Han, Xuze; Yan, Mingquan

2018-02-20

The recently developed three-step ternary halogenation model interprets the incorporation of chlorine, bromine, and iodine ions into natural organic matter (NOM) and formation of iodine-, bromine-, and chlorine-containing trihalomethanes (THMs) based on the competition of iodine, bromine, and chlorine species at each node of the halogenation sequence. This competition is accounted for using the dimensionless ratios (denoted as γ) of kinetic rates of reactions of the initial attack sites or halogenated intermediates with chlorine, bromine, and iodine ions. However, correlations between the model predictions made and mechanistic aspects of the incorporation of halogen species need to be ascertained in more detail. In this study, quantum chemistry calculations were first used to probe the formation mechanism of 10 species of Cl-/Br-/I- THMs. The HOMO energy (E HOMO ) of each mono-, bi-, or trihalomethanes were calculated by B3LYP method in Gaussian 09 software. Linear correlations were found to exist between the logarithms of experimentally determined kinetic preference coefficients γ reported in prior research and, on the other hand, differences of E HOMO values between brominated/iodinated and chlorinated halomethanes. One notable exception from this trend was that observed for the incorporation of iodine into mono- and di-iodinated intermediates. These observations confirm the three-step halogen incorporation sequence and the factor γ in the statistical model. The combined use of quantum chemistry calculations and the ternary sequential halogenation model provides a new insight into the microscopic nature of NOM-halogen interactions and the trends seen in the behavior of γ factors incorporated in the THM speciation models.

Boiling points of halogenated aliphatic compounds: a quantitative structure-property relationship for prediction and validation.

Science.gov (United States)

Oberg, Tomas

2004-01-01

Halogenated aliphatic compounds have many technical uses, but substances within this group are also ubiquitous environmental pollutants that can affect the ozone layer and contribute to global warming. The establishment of quantitative structure-property relationships is of interest not only to fill in gaps in the available database but also to validate experimental data already acquired. The three-dimensional structures of 240 compounds were modeled with molecular mechanics prior to the generation of empirical descriptors. Two bilinear projection methods, principal component analysis (PCA) and partial-least-squares regression (PLSR), were used to identify outliers. PLSR was subsequently used to build a multivariate calibration model by extracting the latent variables that describe most of the covariation between the molecular structure and the boiling point. Boiling points were also estimated with an extension of the group contribution method of Stein and Brown.

Performance analysis of photoresistor and phototransistor for automotive’s halogen and xenon bulbs light output

Science.gov (United States)

Rammohan, A.; Kumar, C. Ramesh

2017-11-01

Illumination of any light is measured using a different kind of calibrated equipment’s available in the market such as a goniometer, spectral radiometer, photometer, Lux meter and camera based systems which directly display the illumination of automotive headlights light distribution in the unit of lux, foot-candles, lumens/sq. ft. and Lambert etc., In this research, we dealt with evaluating the photo resistor or Light Dependent Resistor (LDR) and phototransistor whether it is useful for sensing light patterns of Automotive Halogen and Xenon bulbs. The experiments are conducted during night hours under complete dark space. We have used the headlamp setup available in TATA SUMO VICTA vehicle in the Indian market and conducted the experiments separately for Halogen and Xenon bulbs under low and high beam operations at various degrees and test points within ten meters of distance. Also, we have compared the light intensity of halogen and xenon bulbs to prove the highest light intensity between halogen and Xenon bulbs. After doing a rigorous test with these two sensors it is understood both are good to sensing beam pattern of automotive bulbs and even it is good if we use an array of sensors or a mixed combination of sensors for measuring illumination purposes under perfect calibrations.

40 CFR Table 3 to Subpart Ffff of... - Emission Limits for Hydrogen Halide and Halogen HAP Emissions or HAP Metals Emissions From...

Science.gov (United States)

2010-07-01

... Halogen HAP Emissions or HAP Metals Emissions From Process Vents 3 Table 3 to Subpart FFFF of Part 63... to Subpart FFFF of Part 63—Emission Limits for Hydrogen Halide and Halogen HAP Emissions or HAP... following table that applies to your process vents that contain hydrogen halide and halogen HAP emissions or...

Protection of halogenated DNA from strand breakage and sister-chromatid exchange induced by the topoisomerase I inhibitor camptothecin

International Nuclear Information System (INIS)

Orta, Manuel Luis; Mateos, Santiago; Cantero, Gloria; Wolff, Lisa J.; Cortes, Felipe

2008-01-01

The fundamental nuclear enzyme DNA topoisomerase I (topo I), cleaves the double-stranded DNA molecule at preferred sequences within its recognition/binding sites. We have recently reported that when cells incorporate halogenated nucleosides analogues of thymidine into DNA, it interferes with normal chromosome segregation, as shown by an extraordinarily high yield of endoreduplication, and results in a protection against DNA breakage induced by the topo II poison m-AMSA [F. Cortes, N. Pastor, S. Mateos, I. Dominguez, The nature of DNA plays a role in chromosome segregation: endoreduplication in halogen-substituted chromosomes, DNA Repair 2 (2003) 719-726; G. Cantero, S. Mateos, N. Pastor; F. Cortes, Halogen substitution of DNA protects from poisoning of topoisomerase II that results in DNA double-strand breaks (DSBs), DNA Repair 5 (2006) 667-674]. In the present investigation, we have assessed whether the presence of halogenated nucleosides in DNA diminishes the frequency of interaction of topo I with DNA and thus the frequency with which the stabilisation of cleavage complexes by the topo I poison camptothecin (CPT) takes place, in such a way that it protects from chromosome breakage and sister-chromatid exchange. This protective effect is shown to parallel a loss in halogen-substituted cells of the otherwise CPT-increased catalytic activity bound to DNA

Pharmacological evaluation of halogenated and non-halogenated arylpiperazin-1-yl-ethyl-benzimidazoles as D(2) and 5-HT(2A) receptor ligands.

Science.gov (United States)

Tomić, Mirko; Vasković, Djurdjica; Tovilović, Gordana; Andrić, Deana; Penjišević, Jelena; Kostić-Rajačić, Sladjana

2011-05-01

Five groups of previously synthesized and initially screened non-substituted and 4-halogenated arylpiperazin-1-yl-ethyl-benzimidazoles were estimated for their in-vitro binding affinities at the rat D(2) , 5-HT(2A) , and α(1) -adrenergic receptors. Among all these compounds, 2-methoxyphenyl and 2-chlorophenyl piperazines demonstrate the highest affinities for the tested receptors. The effects of 4-halogenation of benzimidazoles reveal that substitution with bromine may greatly increase the affinity of the compounds for the studied receptors, while the effect of substitution with chlorine is less remarkable. Most of the tested components show 5-HT(2A)/D(2) pK(i) binding ratios slightly above or less than 1, while only 4-chloro-6-(2-{4-[3-(trifluoromethyl)phenyl]piperazin-1-yl}ethyl)-1H-benzimidazole expresses an appropriate higher binding ratio (1.14), which was indicated for atypical neuroleptics. This compound exhibits a non-cataleptic action in rats and prevents d-amphetamine-induced hyperlocomotion in mice, which suggest its atypical antipsychotic potency. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chromatographic resolution of closely related species in pharmaceutical chemistry: dehalogenation impurities and mixtures of halogen isomers.

Science.gov (United States)

Regalado, Erik L; Zhuang, Ping; Chen, Yadan; Makarov, Alexey A; Schafer, Wes A; McGachy, Neil; Welch, Christopher J

2014-01-07

In recent years, the use of halogen-containing molecules has proliferated in the pharmaceutical industry, where the incorporation of halogens, especially fluorine, has become vitally important for blocking metabolism and enhancing the biological activity of pharmaceuticals. The chromatographic separation of halogen-containing pharmaceuticals from associated isomers or dehalogenation impurities can sometimes be quite difficult. In an attempt to identify the best current tools available for addressing this important problem, a survey of the suitability of four chromatographic method development platforms (ultra high-performance liquid chromatography (UHPLC), core shell HPLC, achiral supercritical fluid chromatography (SFC) and chiral SFC) for separating closely related mixtures of halogen-containing pharmaceuticals and their dehalogenated isosteres is described. Of the 132 column and mobile phase combinations examined for each mixture, a small subset of conditions were found to afford the best overall performance, with a single UHPLC method (2.1 × 50 mm, 1.9 μm Hypersil Gold PFP, acetonitrile/methanol based aqueous eluents containing either phosphoric or perchloric acid with 150 mM sodium perchlorate) affording excellent separation for all samples. Similarly, a survey of several families of closely related halogen-containing small molecules representing the diversity of impurities that can sometimes be found in purchased starting materials for synthesis revealed chiral SFC (Chiralcel OJ-3 and Chiralpak IB, isopropanol or ethanol with 25 mM isobutylamine/carbon dioxide) as well as the UHPLC (2.1 × 50 mm, 1.8 μm ZORBAX RRHD Eclipse Plus C18 and the Gold PFP, acetonitrile/methanol based aqueous eluents containing phosphoric acid) as preferred methods.

Four groups of new aromatic halogenated disinfection byproducts: effect of bromide concentration on their formation and speciation in chlorinated drinking water.

Science.gov (United States)

Pan, Yang; Zhang, Xiangru

2013-02-05

Bromide is naturally present in source waters worldwide. Chlorination of drinking water can generate a variety of chlorinated and brominated disinfection byproducts (DBPs). Although substantial efforts have been made to examine the effect of bromide concentration on the formation and speciation of halogenated DBPs, almost all previous studies have focused on trihalomethanes and haloacetic acids. Given that about 50% of total organic halogen formed in chlorination remains unknown, it is still unclear how bromide concentration affects the formation and speciation of the new/unknown halogenated DBPs. In this study, chlorinated drinking water samples with different bromide concentrations were prepared, and a novel approach-precursor ion scan using ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry-was adopted for the detection and identification of polar halogenated DBPs in these water samples. With this approach, 11 new putative aromatic halogenated DBPs were identified, and they were classified into four groups: dihalo-4-hydroxybenzaldehydes, dihalo-4-hydroxybenzoic acids, dihalo-salicylic acids, and trihalo-phenols. A mechanism for the formation of the four groups of new aromatic halogenated DBPs was proposed. It was found that increasing the bromide concentration shifted the entire polar halogenated DBPs as well as the four groups of new DBPs from being less brominated to being more brominated; these new aromatic halogenated DBPs might be important intermediate DBPs formed in drinking water chlorination. Moreover, the speciation of the four groups of new DBPs was modeled: the speciation patterns of the four groups of new DBPs well matched those determined from the model equations, and the reactivity differences between HOBr and HOCl in reactions forming the four groups of new DBPs were larger than those in reactions forming trihalomethanes and haloacetic acids.

A Protein Data Bank survey reveals shortening of intermolecular hydrogen bonds in ligand-protein complexes when a halogenated ligand is an H-bond donor.

Science.gov (United States)

Poznański, Jarosław; Poznańska, Anna; Shugar, David

2014-01-01

Halogen bonding in ligand-protein complexes is currently widely exploited, e.g. in drug design or supramolecular chemistry. But little attention has been directed to other effects that may result from replacement of a hydrogen by a strongly electronegative halogen. Analysis of almost 30000 hydrogen bonds between protein and ligand demonstrates that the length of a hydrogen bond depends on the type of donor-acceptor pair. Interestingly, lengths of hydrogen bonds between a protein and a halogenated ligand are visibly shorter than those estimated for the same family of proteins in complexes with non-halogenated ligands. Taking into account the effect of halogenation on hydrogen bonding is thus important when evaluating structural and/or energetic parameters of ligand-protein complexes. All these observations are consistent with the concept that halogenation increases the acidity of the proximal amino/imino/hydroxyl groups and thus makes them better, i.e. stronger, H-bond donors.

UV-visible and resonance Raman spectroscopy of halogen molecules in clathrate hydrates

Energy Technology Data Exchange (ETDEWEB)

Janda, K.C.; Kerenskaya, G.; Goldsheleger, I.U.; Apkarian, V.A.; Fleischer, E.B. [California Univ., Irvine, CA (United States). Dept. of Chemistry

2008-07-01

Resonance Raman spectroscopy was used to study halogen clathrate hydrate solids. In particular, this paper presented an ultraviolet-visible spectra for a polycrystalline sample of chlorine clathrate hydrate and two single crystal samples of bromine clathrate hydrate. UV-visible spectroscopy was used to study the interactions between the halogen guest molecule and the host water lattice. The spectrum for chlorine hydrate had a strong temperature dependence, while the spectra for bromine clathrate hydrate single crystals had a stable cubic type 2 structure as well as a tetragonal structure. A metastable cubic type 1 structure was also observed. Resonance Raman spectroscopy showed how the molecules fit into the host cages. 25 refs., 2 tabs., 7 figs.

Field and numerical descriptions of fracture geometries and terminations in chalk containing chert layers and inclusions; implications for groundwater flow in Danish chalk aquifers

Science.gov (United States)

Seyum, S.

2017-12-01

This study is a description of the fracture distribution in laterally discontinuous chalk and chert layers, with an investigation on how fracture lengths and apertures vary as a function of applied stresses, material properties, and interface properties. Natural fractures intersect laterally extensive, discontinuous, chalk-chert material interfaces in 62 million-year old to 72 million-year old Chalk Group formations exposed at Stevns Klint, Denmark. Approximately one-third of Denmark's fresh water use is from chalk and limestone regional aquifers of the Chalk Group formations, where rock permeability is dominantly a function of open fracture connectivities. Fractured, centimeter- to decimeter-thick chert layers and inclusions (101 GPa elastic stiffness) are interlayered with fractured, meter-thick chalk layers (100 GPa elastic stiffness). Fractures are observed to terminate against and cross chalk-chert interfaces, affecting the vertical flow of water and pollutants between aquifers. The discontinuous and variably thin nature of chert layers at Stevns Klint effectively merges adjacent fracture-confining layers of chalk along discrete position intervals, resulting in lateral variability of fracture spacing. Finite element numerical models are designed to describe fracture interactions with stiff, chert inclusions of various shapes, thicknesses, widths, orientations, and interface friction and fracture toughness values. The models are two-dimensional with isotropic, continuous material in plane strain and uniformly applied remote principal stresses. These characteristics are chosen based on interpretations of the petrophysics of chalk and chert, the burial history of the rock, and the scale of investigation near fracture tips relative to grain sizes. The result are value ranges for relative stiffness contrasts, applied stresses, and material interface conditions that would cause fractures to cross, terminate at, or form along chalk-chert interfaces, with emphasis on

SYNTHESIS AND STUDY OF HALOGENATED BENZYLAMIDES OF SOME ISOCYCLIC AND HETEROCYCLIC ACIDS AS POTENTIAL ANTICONVULSANTS.

Science.gov (United States)

Strupińska, Marzanna; Rostafińska-Suchar, Grażyna; Pirianowicz-Chaber, Elżbieta; Grabczuk, Mateusz; Józwenko, Magdalena; Kowalczyk, Hubert; Szuba, Joanna; Wójcicka, Monika; Chen, Tracy; Mazurek, Aleksander P

2015-01-01

A series of potential anticonvulsants have been synthesized. There are eight fluorobenzylamides and three chlorobenzylamides of isocyclic or heterocyclic acids. Two not halogenated benzylamides were also synthesized to compare the effect of halogenation. The aim of the research performed was to evaluate whether halogenation of the mother structure is able to improve its anticonvulsant activity. The compounds were tested in Anticonvulsant Screening Project (ASP) of Antiepileptic Drug Development Program (ADDP) of NIH. Compound 1 showed MES ED50 = 80.32 mg/kg, PI = 3.16. Compound 7 showed CKM ED50 = 56.72 mg/kg. Compound 8 showed MES ED50 = 34.23 mg/kg and scPTZ ED50 > 300 mg/kg, PI = 8.53.Compound 13 showed 6Hz ED50 = 78.96, PI = 3.37. The results indicate that fluorination does not improve activity, whereas chlorination in our experiment even reduces it.

Computational insights into the photocyclization of diclofenac in solution: effects of halogen and hydrogen bonding.

Science.gov (United States)

Bani-Yaseen, Abdulilah Dawoud

2016-08-21

The effects of noncovalent interactions, namely halogen and hydrogen bonding, on the photochemical conversion of the photosensitizing drug diclofenac (DCF) in solution were investigated computationally. Both explicit and implicit solvent effects were qualitatively and quantitatively assessed employing the DFT/6-31+G(d) and SQM(PM7) levels of theory. Full geometry optimizations were performed in solution for the reactant DCF, hypothesized radical-based intermediates, and the main product at both levels of theories. Notably, in good agreement with previous experimental results concerning the intermolecular halogen bonding of DCF, the SQM(PM7) method revealed different values for d(ClO, Å) and ∠(C-ClO, °) for the two chlorine-substituents of DCF, with values of 2.63 Å/162° and 3.13 Å/142° for the trans and cis orientations, respectively. Employing the DFT/6-31+G(d) method with implicit solvent effects was not conclusive; however, explicit solvent effects confirmed the key contribution of hydrogen and halogen bonding in stabilizing/destabilizing the reactant and hypothesized intermediates. Interestingly, the obtained results revealed that a protic solvent such as water can increase the rate of photocyclization of DCF not only through hydrogen bonding effects, but also through halogen bonding. Furthermore, the atomic charges of atoms majorly involved in the photocyclization of DCF were calculated using different methods, namely Mulliken, Hirshfeld, and natural bond orbital (NBO). The obtained results revealed that in all cases there is a notable nonequivalency in the noncovalent intermolecular interactions of the two chlorine substituents of DCF and the radical intermediates with the solvent, which in turn may account for the discrepancy of their reactivity in different media. These computational results provide insight into the importance of halogen and hydrogen bonding throughout the progression of the photochemical conversion of DCF in solution.

Is there theoretical evidence for mutual influence between halogen

Indian Academy of Sciences (India)

Based on many-body analysis, two and three-body terms of interaction energies have a positive contribution to the total interaction energy. It was found that the amount of charge transfer in the triads is higher than that in the corresponding dyads. AIM analyses showed that the halogen and pnicogen-hydride bonds in the ...

A Protein Data Bank survey reveals shortening of intermolecular hydrogen bonds in ligand-protein complexes when a halogenated ligand is an H-bond donor.

Directory of Open Access Journals (Sweden)

Jarosław Poznański

Full Text Available Halogen bonding in ligand-protein complexes is currently widely exploited, e.g. in drug design or supramolecular chemistry. But little attention has been directed to other effects that may result from replacement of a hydrogen by a strongly electronegative halogen. Analysis of almost 30000 hydrogen bonds between protein and ligand demonstrates that the length of a hydrogen bond depends on the type of donor-acceptor pair. Interestingly, lengths of hydrogen bonds between a protein and a halogenated ligand are visibly shorter than those estimated for the same family of proteins in complexes with non-halogenated ligands. Taking into account the effect of halogenation on hydrogen bonding is thus important when evaluating structural and/or energetic parameters of ligand-protein complexes. All these observations are consistent with the concept that halogenation increases the acidity of the proximal amino/imino/hydroxyl groups and thus makes them better, i.e. stronger, H-bond donors.

Laboratory Investigations of Stratospheric Halogen Chemistry

Science.gov (United States)

Wine, Paul H.; Nicovich, J. Michael; Stickel, Robert E.; Hynes, Anthony J.

1997-01-01

A final report for the NASA-supported project on laboratory investigations of stratospheric halogen chemistry is presented. In recent years, this project has focused on three areas of research: (1) kinetic, mechanistic, and thermochemical studies of reactions which produce weakly bound chemical species of atmospheric interest; (2) development of flash photolysis schemes for studying radical-radical reactions of stratospheric interest; and (3) photochemistry studies of interest for understanding stratospheric chemistry. The first section of this paper contains a discussion of work which has not yet been published. All subsequent chapters contain reprints of published papers that acknowledge support from this grant.

Synthesis and Application of a Novel Polyamide Charring Agent for Halogen-Free Flame Retardant Polypropylene

Directory of Open Access Journals (Sweden)

Jie Liu

2013-01-01

Full Text Available A novel charring agent, poly(p-ethylene terephthalamide (PETA, for halogen-free flame retardant polypropylene was synthesized by using p-phthaloyl chloride (TPC and ethylenediamine through solution polycondensation at low temperature, and the effects of PETA on flame retardance of polypropylene (PP/IFR systems were studied. The experimental results showed that PETA could considerably enhance the fire retardant performance as proved by evidence of the increase of limiting oxygen index (LOI values, the results of UL-94 tests, and cone calorimeter tests (CCT. Fourier transform infrared spectroscopy (FTIR and scanning electron microscope (SEM demonstrated that an appropriate amount of PETA could react with PP/IFR system to form cross-link network; a more compact char layer could be formed which was responsible for the improved thermal and flame retardant properties of PP/IFR systems. However, the superfluous amount of PETA would play the negative role.

The Halogenated Metabolism of Brown Algae (Phaeophyta, Its Biological Importance and Its Environmental Significance

Directory of Open Access Journals (Sweden)

Stéphane La Barre

2010-03-01

Full Text Available Brown algae represent a major component of littoral and sublittoral zones in temperate and subtropical ecosystems. An essential adaptive feature of this independent eukaryotic lineage is the ability to couple oxidative reactions resulting from exposure to sunlight and air with the halogenations of various substrates, thereby addressing various biotic and abiotic stresses i.e., defense against predators, tissue repair, holdfast adhesion, and protection against reactive species generated by oxidative processes. Whereas marine organisms mainly make use of bromine to increase the biological activity of secondary metabolites, some orders of brown algae such as Laminariales have also developed a striking capability to accumulate and to use iodine in physiological adaptations to stress. We review selected aspects of the halogenated metabolism of macrophytic brown algae in the light of the most recent results, which point toward novel functions for iodide accumulation in kelps and the importance of bromination in cell wall modifications and adhesion properties of brown algal propagules. The importance of halogen speciation processes ranges from microbiology to biogeochemistry, through enzymology, cellular biology and ecotoxicology.

Patterned hydrophobic and hydrophilic surfaces of ultra-smooth nanocrystalline diamond layers

Energy Technology Data Exchange (ETDEWEB)

Mertens, M., E-mail: michael.mertens@uni-ulm.de [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Mohr, M.; Brühne, K.; Fecht, H.J. [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Łojkowski, M.; Święszkowski, W. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw (Poland); Łojkowski, W. [Institute of High Pressure Physics, Polish Academy of Sciences, Warsaw (Poland)

2016-12-30

Highlights: • Hydrophobic and hydrophilic properties on fluorine-, hydrogen- and oxygen- terminated ultra-nanocrystalline diamond films. • Micropatterned - multi-terminated layers with both hydrophobic and hydrophilic areas on one sample. • Visualization of multi-terminated surfaces by e.g. SEM and LFM. • Roughness and friction investigations on different terminated surfaces. • Smooth and biocompatible surfaces with same roughness regardless of hydrophobicity for microbiological investigations. - Abstract: In this work, we show that ultra nanocrystalline diamond (UNCD) surfaces have been modified to add them hydrophobic and hydrophilic properties. The nanocrystalline diamond films were deposited using the hot filament chemical vapor deposition (HFCVD) technique. This allows growing diamond on different substrates which can be even 3D or structured. Silicon and, for optical applications, transparent quartz glass are the preferred substrates for UNCD layers growth. Fluorine termination leads to strong hydrophobic properties as indicated by a high contact angle for water of more than 100°. Hydrogen termination shows lesser hydrophobic behavior. Hydrophilic characteristics has been realised with oxygen termination. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) measurements confirm the oxygen and fluorine- termination on the nanocrystalline diamond surface. Further, by micropatterning using photolithography, multi-terminated layers have been created with both hydrophobic and hydrophilic areas. In addition, we have shown that retermination is achieved, and the properties of the surface have been changed from hydrophobic to hydrophilic and vice versa. Micro- roughness and stress in the grown film influences slightly the wetting angle as well. The opportunity to realize local differences in hydrophobicity on nanocrystalline diamond layers, in any size or geometry, offers interesting applications for example in

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1980-February 14, 1981

International Nuclear Information System (INIS)

1981-02-01

The stereochemistry of high energy 18 F, /sup 34m/Cl, and 76 Br substitution reactions involving enantiomeric molecules in the gas and condensed phase is studied. The gas to condensed state transition in halogen high energy chemistry, involving chlorine, bromine, and iodine activated by the (n,γ) and (I.T.) processes in halomethanes, saturated and unsaturated hydrocarbons is being investigated in more detail. Special attention is given to defining the nature of the enhancement yields in the condensed phase. High energy halogen reactions in liquid and frozen aqueous solutions of organic and biomolecular solutes are studied in an attempt to learn more about these reactions. The applications of high energy chemistry techniques and theory to neutron activation analysis of biological systems are being continued. Special attention is given to developing procedures for trace molecular determinations in biological systems. The applications of hot halogen atoms as indicators of solute-solute interactions in liquid and frozen aqueous solutions of halogenated bases and nucleosides are being developed. Experiments are designed to explain the mechanisms of the radioprotection offered biomolecular solutes trapped within the frozen ice lattice. Reactions of bromine and iodine activated by isomeric transition with halogenated biomolecular solutes in liquid and frozen aqueous solutions are studied. The high energy reactions of iodine with the isomers of pentene have been studied in low pressure gaseous systems employing additives and rare gas moderators and liquid systems. Reactivity of excited complex formation and structural effects of electrophilic iodine attack on the pi-bond systems are studied

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1980-February 14, 1981

Energy Technology Data Exchange (ETDEWEB)

1981-02-01

The stereochemistry of high energy /sup 18/F, /sup 34m/Cl, and /sup 76/Br substitution reactions involving enantiomeric molecules in the gas and condensed phase is studied. The gas to condensed state transition in halogen high energy chemistry, involving chlorine, bromine, and iodine activated by the (n,..gamma..) and (I.T.) processes in halomethanes, saturated and unsaturated hydrocarbons is being investigated in more detail. Special attention is given to defining the nature of the enhancement yields in the condensed phase. High energy halogen reactions in liquid and frozen aqueous solutions of organic and biomolecular solutes are studied in an attempt to learn more about these reactions. The applications of high energy chemistry techniques and theory to neutron activation analysis of biological systems are being continued. Special attention is given to developing procedures for trace molecular determinations in biological systems. The applications of hot halogen atoms as indicators of solute-solute interactions in liquid and frozen aqueous solutions of halogenated bases and nucleosides are being developed. Experiments are designed to explain the mechanisms of the radioprotection offered biomolecular solutes trapped within the frozen ice lattice. Reactions of bromine and iodine activated by isomeric transition with halogenated biomolecular solutes in liquid and frozen aqueous solutions are studied. The high energy reactions of iodine with the isomers of pentene have been studied in low pressure gaseous systems employing additives and rare gas moderators and liquid systems. Reactivity of excited complex formation and structural effects of electrophilic iodine attack on the pi-bond systems are studied.

Effect of Ge surface termination on oxidation behavior

Science.gov (United States)

Lee, Younghwan; Park, Kibyung; Cho, Yong Soo; Lim, Sangwoo

2008-09-01

Sulfur-termination was formed on the Ge(1 0 0) surface using (NH 4) 2S solution. Formation of Ge-S and the oxidation of the S-terminated Ge surface were monitored with multiple internal reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. In the 0.5, 5, or 20% (NH 4) 2S solution, H-termination on the Ge(1 0 0) surface was substituted with S-termination in 1 min. When the S-terminated Ge(1 0 0) surface was exposed in air ambient, the oxidation was retarded for about 3600 min. The preservation time of the oxide layer up to one monolayer of S-terminated Ge(1 0 0) surface was about 120 times longer than for the H-terminated Ge(1 0 0) surface. However, the oxidation of S-terminated Ge(1 0 0) surface drastically increased after the threshold time. There was no significant difference in threshold time between S-terminations formed in 0.5, 5, and 20% (NH 4) 2S solutions. With the surface oxidation, desorption of S on the Ge surface was observed. The desorption behavior of sulfur on the S-terminated Ge(1 0 0) surface was independent of the concentration of the (NH 4) 2S solution that forms S-termination. Non-ideal S-termination on Ge surfaces may be related to drastic oxidation of the Ge surface. Finally, with the desulfurization on the S-terminated Ge(1 0 0) surface, oxide growth is accelerated.

Neutron activation analysis for study of distribution patterns of organo-halogen pollutants in apple

International Nuclear Information System (INIS)

Zhang Hong; Luo Jialing; Sun Huibin; Chai Zhifang; Chinese Academy of Sciences, Beijing

2007-01-01

The distribution characteristics of organo-halogens in apple and their sources were studied by neutron activation analysis combined with statistical analysis. The results indicated that concentrations of organo-halogens in apple were in the order of organo-chlorine >> organo-bromine > organo-iodine, and concentrations of the organo-chlorine in four parts of apple were in the order of seed >> peel >> endocarp ≥ pulp. Also, the organo-chlorine, -bromine and-iodine in apple were found to have different sources. The latter two were mainly from naturally synthetic products by plant itself, while the former was mainly from anthropogenic pollutants. (authors)

Halogen effect for improving high temperature oxidation resistance of Ti-50Al by anodization

Science.gov (United States)

Mo, Min-Hua; Wu, Lian-Kui; Cao, Hua-Zhen; Lin, Jun-Pin; Zheng, Guo-Qu

2017-06-01

The high temperature oxidation resistance of Ti-50Al was significantly improved via halogen effect which was achieved by anodizing in an ethylene glycol solution containing with fluorine ion. The anodized Ti-50Al with holes and micro-cracks could be self-repaired during oxidation at 1000 °C. The thickness of the oxide scale increases with the prolonging of oxidation time. On the basis of halogen effect for improving the high temperature oxidation resistance of Ti-50Al by anodization, only fluorine addition into the electrolyte can effectively improve the high temperature oxidation resistance of Ti-50Al.

Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants

Science.gov (United States)

Yoshida, Suguru; Fujita, Yasunobu

The current state of knowledge on heat transfer to boiling refrigerants (halogenated hydrocarbons) in a pool and flowing inside a horizontal tube is reviewed with an emphasis on information relevant to the design of refrigerant evaporators, and some recommendations are made for future research. The review covers two-phase flow pattern, heat transfer characteristics, correlation of heat transfer coefficient, influence of oil, heat transfer augmentation, boiling from tube-bundle, influence of return bend, burnout heat flux, film boiling, dryout and post-dryout heat transfer.

Gas-liquid partitioning of halogenated volatile organic compounds in aqueous cyclodextrin solutions

Energy Technology Data Exchange (ETDEWEB)

Ondo, Daniel; Barankova, Eva [Department of Physical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Dohnal, Vladimir, E-mail: dohnalv@vscht.cz [Department of Physical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic)

2011-08-15

Highlights: > Binding of halogenated VOCs with cyclodextrins examined through g-l partitioning. > Complex stabilities reflect host-guest size matching and hydrophobic interaction. > Presence of halogens in the guest molecule stabilizes the binding. > Thermodynamic origin of the binding varies greatly among the systems studied. > Results obey the guest-CD global enthalpy-entropy compensation relationship. - Abstract: Gas-liquid partitioning coefficients (K{sub GL}) were measured for halogenated volatile organic compounds (VOCs), namely 1-chlorobutane, methoxyflurane, pentafluoropropan-1-ol, heptafluorobutan-1-ol, {alpha},{alpha},{alpha}-trifluorotoluene, and toluene in aqueous solutions of natural {alpha}-, {beta}-, and {gamma}-cyclodextrins (CDs) at temperatures from (273.35 to 326.35) K employing the techniques of headspace gas chromatography and inert gas stripping. The binding constants of the 1:1 inclusion complex formation between the VOCs and CDs were evaluated from the depression of the VOCs volatility as a function of CD concentration. The host-guest size matching and the hydrophobic interaction concept were used to rationalize the observed widely different affinity of the VOC-CD pairs to form the inclusion complex. The enthalpic and entropic component of the standard Gibbs free energy of complex formation as derived from the temperature dependence of the binding constant indicate the thermodynamic origin of the binding to vary greatly among the systems studied, but follow the global enthalpy-entropy compensation relationships reported previously in the literature.

Hydration of the Atlantis Massif: Halogen, Noble Gas and In-Situ δ18O Constraints

Science.gov (United States)

Williams, M. J.; Kendrick, M. A.; Rubatto, D.

2017-12-01

A combination of halogen (Cl, Br, I), noble gases (He, Ne, Ar, Kr and Xe) and in situ oxygen isotope analysis have been utilized to investigate the fluid-mobile element record of hydration and alteration processes at the Atlantis Massif (30°N on the Mid-Atlantic Ridge). The sample suite investigated includes serpentinite, talc-amphibole ± chlorite schist and hydrated gabbro recovered by seafloor drilling undertaken at sites on a transect across the Atlantis Massif during IODP Expedition 357. Serpentine mesh and veins analysed in-situ by SHRIMP SI exhibit δ18O from 6‰ down to ≈0‰, suggesting serpentinization temperatures of 150 to >280°C and water/rock ratios >5. Differences of 1.5-2.5‰ are observed between adjacent generations of serpentine, but the δ18O range is similar at each investigated drilling site. Halogen and noble gas abundances in serpentinites, talc-amphibole schist and hydrated gabbro have been measured by noble gas mass spectrometry of both irradiated and non-irradiated samples. Serpentinites contain low abundances of halogens and noble gases (e.g. 70-430 ppm Cl, 4.7-12.2 x 10-14 mol/g 36Ar) relative to other seafloor serpentinites. The samples have systematically different Br/Cl and I/Cl ratios related to their mineralogy. Serpentinites retain mantle-like Br/Cl with a wide variation in I/Cl that stretches toward seawater values. Talc-amphibole schists exhibit depletion of Br and I relative to Cl with increasing Cl abundances, suggesting tremolite exerts strong control on halogen abundance ratios. Serpentinites show no evidence of interaction with halogen-rich sedimentary pore fluids. Iodine abundances are variable across serpentinites, and are decoupled from Br and Cl; iodine enrichment (up to 530 ppb) is observed within relatively oxidised and clay-bearing samples. Serpentinized harzburgites exhibit distinct depletion of Kr and Xe relative to atmospheric 36Ar in seawater. Oxygen isotope compositions and low abundances of both halogens

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.

A facile approach towards increasing the nitrogen-content in nitrogen-doped carbon nanotubes via halogenated catalysts

International Nuclear Information System (INIS)

Ombaka, L.M.; Ndungu, P.G.; Omondi, B.; McGettrick, J.D.; Davies, M.L.; Nyamori, V.O.

2016-01-01

Nitrogen-doped carbon nanotubes (N-CNTs) have been synthesized at 850 °C via a CVD deposition technique by use of three ferrocenyl derivative catalysts, i.e. para-CN, -CF_3 and -Cl substituted-phenyl rings. The synthesized catalysts have been characterized by NMR, IR, HR-MS and XRD. The XRD analysis of the para-CF_3 catalyst indicates that steric factors influence the X-ray structure of 1,1′-ferrocenylphenyldiacrylonitriles. Acetonitrile or pyridine was used as carbon and nitrogen sources to yield mixtures of N-CNTs and carbon spheres (CS). The N-CNTs obtained from the para-CF_3 catalysts, in pyridine, have the highest nitrogen-doping level, show a helical morphology and are less thermally stable compared with those synthesized by use of the para-CN and -Cl as catalyst. This suggests that fluorine heteroatoms enhance nitrogen-doping in N-CNTs and formation of helical-N-CNTs (H-N-CNTs). The para-CF_3 and para-Cl catalysts in acetonitrile yielded iron-filled N-CNTs, indicating that halogens promote encapsulation of iron into the cavity of N-CNT. The use of acetonitrile, as carbon and nitrogen source, with the para-CN and -Cl as catalysts also yielded a mixture of N-CNTs and carbon nanofibres (CNFs), with less abundance of CNFs in the products obtained using para-Cl catalysts. However, para-CF_3 catalyst in acetonitrile gave N-CNTs as the only shaped carbon nanomaterials. - Graphical abstract: Graphical abstract showing the synthesis of N-CNTs using halogenated-ferrocenyl derivatives as catalyst with pyridine or acetonitrile as nitrogen and carbon sources via the chemical vapour deposition technique. - Highlights: • N-CNTs were synthesized from halogenated ferrocenyl catalysts. • Halogenated catalysts promote nitrogen-doping and pyridinic nitrogen in N-CNTs. • Halogenated catalysts facilitate iron filling of N-CNTs.

Basic aspects of photocatalytic detoxification of organic halogens by TiO2 nanocrystallites. Photolytic and radiolytic investigations

International Nuclear Information System (INIS)

Rabani, J.

1998-01-01

Various forms of TiO 2 (nanocrystallites in colloid solutions, powders and layers) are considered as promising photocatalysts for detoxification of persistent organic chemicals which are present as pollutants in waste water effluents from industrial manufacturers and even from regular households. Such pollutants penetrate and reach water sources and must be removed or destroyed in order to prevent damage to people or to the environment. Some of the toxins, such as organic halogenated compounds is difficult to remove by moderate chemical redox reactions, but can be mineralized by a free radical mechanism. Pilot plants for detoxification of industrial wastes on TiO 2 surface are currently being tested in several countries. In view of this recent development it is of particular interest to investigate yields of the reactive intermediates and reaction mechanisms of reactions of representative organic substrates. Such work is presently going on in many laboratories. In the present contribution we focus on the nature of the primary oxidizing species and the possible ways to increase photolytic yields, with particular attention to chain reactions in organic halogen compounds. Although the work concerns photocatalysis, radiation chemistry may provide useful results regarding kinetic parameters and comparative tests. Thus, comparison between photocatalytic (TiO 2 ), radiolytic and chemical hydroxylations of phenol provides evidence that the reactive hydroxylation agent is an OH· radical adsorbed to the TiO 2 surface. The initial photochemical products are conduction band electrons and valence band holes in the TiO 2 nanocrystallites, which become 'trapped' within less than 30 ps. (author)

Process for removing halogenated aliphatic and aromatic compounds from petroleum products. [Polychlorinated biphenyls; methylene chloride; perchloroethylene; trichlorofluoroethane; trichloroethylene; chlorobenzene

Science.gov (United States)

Googin, J.M.; Napier, J.M.; Travaglini, M.A.

1982-03-31

A process for removing halogenated aliphatic and aromatic compounds, e.g., polychlorinated biphenyls, from petroleum products by solvent extraction. The halogenated aliphatic and aromatic compounds are extracted from a petroleum product into a polar solvent by contracting the petroleum product with the polar solvent. The polar solvent is characterized by a high solubility for the extracted halogenated aliphatic and aromatic compounds, a low solubility for the petroleum product and considerable solvent power for polyhydroxy compound. The preferred polar solvent is dimethylformamide. A miscible polyhydroxy compound, such as, water, is added to the polar extraction solvent to increase the polarity of the polar extraction solvent. The halogenated aliphatic and aromatic compounds are extracted from the highly-polarized mixture of polyhydroxy compound and polar extraction solvent into a low polar or nonpolar solvent by contacting the polyhydroxy compound-polar solvent mixture with the low polar or nonpolar solvent. The halogenated aliphatic and aromatic compounds in the low polar or nonpolar solvent by physical means, e.g., vacuum evaporation. The polar and nonpolar solvents are recovered for recycling. The process can easily be designed for continuous operation. Advantages of the process include that the polar solvent and a major portion of the nonpolar solvent can be recycled, the petroleum products are reclaimable and the cost for disposing of waste containing polychlorinated biphenyls is significantly reduced. 2 tables.

Liquid crystals with novel terminal chains as ferroelectric liquid crystal hosts

International Nuclear Information System (INIS)

Cosquer, G.Y.

2000-02-01

Changes to the molecular structure of liquid crystals can have a significant effect upon their mesomorphism and ferroelectric properties. Most of the research in liquid crystal for display applications concentrates on the design and synthesis of novel mesogenic cores to which straight terminal alkyl or alkoxy chains are attached. However, little is known about the effects upon the mesomorphism and ferroelectric properties of varying the terminal chains. The compounds prepared in this work have a common core - a 2,3-difluoroterphenyl unit with a nine-atom alkyl (nonyl) or alkoxy (octyloxy) chain at the 4-position, but with an unusual chain at the 4''-position. In some cases the terminal chain contains hetero atoms such as silicon, oxygen, chlorine and bromine or has a bulky end group. In total 46 final materials were synthesised in an attempt to understand the effect of an unusual terminal chains on mesomorphism and for some of these compounds the effect upon the switching times when added to a standard ferroelectric mixture were investigated. It was found that most compounds containing a bulky end group only displayed a smectic C phase, compounds with a halogen substituent as an end unit displayed a smectic A phase and that increasing the chain flexibility by introducing an oxygen atom in the chain reduces the melting and clearing points. The electro-optical measurements carried out on ferroelectric mixtures containing a bulky end group compound showed that shorter switching times were produced than for the ferroelectric mixture containing a straight chain compound. It is suggested that a bulky end group diminishes te extent of interlayer mixing in the chiral smectic C phase and therefore the molecules move more easily with ferroelectric switching. (author)

Impact of enhanced ozone deposition and halogen chemistry on model performance

Science.gov (United States)

In this study, an enhanced ozone deposition scheme due to the interaction of iodide in sea-water and atmospheric ozone and the detailed chemical reactions of organic and inorganic halogen species are incorporated into the hemispheric Community Multiscale Air Quality model. Prelim...

Tumour radiosensitization with the halogenated pyrimidines 5'-bromo-and 5'-iododeoxyuridine

International Nuclear Information System (INIS)

Epstein, A.H.; Cook, J.A.; Goffman, T.; Glatstein, E.

1993-01-01

The authors review studies of the use of iododeoxyuridine (IdUrd) and bromodeoxyuridine as radiosensitizers and attempt to correlate the clinical outcome for patients treated with radiation and IdUrd with the extent of halogenated pyrimidine cellular uptake and incorporation. (U.K.)

A novel class of halogen-free, super-conductive lithium argyrodites: Synthesis and characterization

Science.gov (United States)

Schneider, Holger; Du, Hui; Kelley, Tracy; Leitner, Klaus; ter Maat, Johan; Scordilis-Kelley, Chariclea; Sanchez-Carrera, Roel; Kovalev, Igor; Mudalige, Anoma; Kulisch, Jörn; Safont-Sempere, Marina M.; Hartmann, Pascal; Weiβ, Thomas; Schneider, Ling; Hinrichsen, Bernd

2017-10-01

Solid electrolytes are the core components for many next generation lithium battery concepts such as all-solid-state batteries (ASSB) or batteries based on metallic lithium anodes protected by a ceramic or composite passivation layer. Therefore, the search for new solid state Li-ion conductors with superior properties and improved electrochemical stabilities remains of high interest. In this work, the synthesis of a new class of silicon-containing, sulfide-based lithium-ion conductors is reported. Very good conductivities of up to ∼2.0-3.0·10-3 S/cm could be achieved for compositions such as Li22SiP2S18, among the highest for silicon sulfide containing materials. Based on the recorded powder XRD diffraction patterns and simulations it could be confirmed that they constitute novel members of the argyrodite family of sulfide lithium-ion conductors. The cubic high-temperature modification of such argyrodites with high lithium-ion conductivity can therefore be stabilized by implementation of silicon into the lattice, while additional doping with halogen atoms is not necessary.

A new non-vital tooth bleaching method using titanium dioxide and 3.5% hydrogen peroxide with a 405-nm diode laser or a halogen lamp

International Nuclear Information System (INIS)

Suemori, T; Kato, J; Nakazawa, T; Akashi, G; Hirai, Y

2008-01-01

To establish a safer and more effective bleaching method for discolored pulpless teeth, we examined bleaching from the pulpal dentin side using a 3.5% hydrogen peroxide solution containing titanium dioxide. The twenty bovine blood-stained discolored enamel-dentin plates of 1.0 mm enamel thickness and 2.0 mm dentin thickness were used. The bleaching agent was applied to the dentin side that was then irradiated with a 405-nm diode laser (800 mW/cm 2 ) or a halogen lamp (720 mW/cm 2 ) for 15 minutes. The bleaching effect was assessed by spectrophotometric measurement of the color of the specimens from the dentin and enamel side for every 5 minutes, and then dentin or enamel surface was examined with a scanning electron microscope. The 3.5% hydrogen peroxide solution containing titanium dioxide proved to have a strong bleaching effect. The color difference after laser irradiation was higher than that after halogen lamp irradiation, however, there was no significant difference between them. No changes in the enamel surface morphology were found and open dentinal tubules with no smear layer were clearly observed at the pulpal dentin surface in both groups

Noncovalent Halogen Bonding as a Mechanism for Gas-Phase Clustering

DEFF Research Database (Denmark)

Wegeberg, Christina; Donald, William A.; McKenzie, Christine

2017-01-01

in the crystalline phases of PhIO2 and its derivatives serve as models for the structures of larger gas-phase clusters, and calculations on simple model gas-phase dimer and trimer clusters result in similar motifs. This is the first account of halogen bonding playing an extensive role in gas-phase associations....

Radiation-induced DNA damage in halogenated pyrimidine incorporated cells and its correlation with radiosensitivity

International Nuclear Information System (INIS)

Watanabe, R.; Nikjoo, H.

2003-01-01

Cells with DNA containing 5-halogenated pyrimidines in place of thymidine show significant reductions of slope (Do) and shoulder (Dq) of their radiation survival curves. Similar radiosensitization has also been observed in the yield of DNA strand breaks. The purpose of this study is to obtain an insight into the mechanism of cell lethality by examining the relationship between the spectrum of DNA damage and the cell survival. In this study we estimated the enhancement of strand breaks due to incorporation of halogenated pyrimidine, the complexity of DNA damage and the probability of the initial DNA damage leading to cell inactivation. Monte Carlo track structure methods were used to model and simulate the induction of strand breakage by X-rays. The increase of DNA strand break was estimated by assuming the excess strand break was caused by the highly reactive uracil radicals at the halouracil substituted sites. The assumption of the enhancement mechanism of strand breaks was examined and verified by comparison with experimental data for induction of SSB and DSB. The calculated DNA damage spectrum shows the increase in complexity of strand breaks is due to incorporation of halogenated pyrimidines. The increase in the yield of DSB and cell lethality show similar trend at various degrees of halogenated pyrimidine substitution. We asked the question whether this agreement supports the hypothesis that DSB is responsible for cell lethality? The estimated number of lethal damage from the cell survival using a linear-quadratic model is much less than the initial yield of DSB. This work examines the correlation of cell lethality as a function of frequencies of complex form of double strand breaks

Multi-layer coatings for bipolar rechargeable batteries with enhanced terminal voltage

Science.gov (United States)

Farmer, Joseph C.; Kaschmitter, James; Pierce, Steve

2017-06-06

A method for producing a multi-layer bipolar coated cell according to one embodiment includes applying a first active cathode material above a substrate to form a first cathode; applying a first solid-phase ionically-conductive electrolyte material above the first cathode to form a first electrode separation layer; applying a first active anode material above the first electrode separation layer to form a first anode; applying an electrically conductive barrier layer above the first anode; applying a second active cathode material above the anode material to form a second cathode; applying a second solid-phase ionically-conductive electrolyte material above the second cathode to form a second electrode separation layer; applying a second active anode material above the second electrode separation layer to form a second anode; and applying a metal material above the second anode to form a metal coating section. In another embodiment, the anode is formed prior to the cathode. Cells are also disclosed.

Antiferromagnetic MnN layer on the MnGa(001) surface

Energy Technology Data Exchange (ETDEWEB)

Guerrero-Sánchez, J., E-mail: guerrero@cnyn.unam.mx; Takeuchi, Noboru

2016-12-30

Highlights: • A ferromagnetic Gallium terminated surface is stable before N incorporation. • After N incorporation, an antiferromagnetic MnN layer becomes stable in a wide range of chemical potential. • Spin density distribution shows an antiferromagnetic/ferromagnetic (MnN/MnGa) arrangement at the surface. - Abstract: Spin polarized first principles total energy calculations have been applied to study the stability and magnetic properties of the MnGa(001) surface and the formation of a topmost MnN layer with the deposit of nitrogen. Before nitrogen adsorption, surface formation energies show a stable gallium terminated ferromagnetic surface. After incorporation of nitrogen atoms, the antiferromagnetic manganese terminated surface becomes stable due to the formation of a MnN layer (Mn-N bonding at the surface). Spin density distribution shows a ferromagnetic/antiferromagnetic arrangement in the first surface layers. This thermodynamically stable structure may be exploited to growth MnGa/MnN magnetic heterostructures as well as to look for exchange biased systems.

Cooperativity of halogen, chalcogen, and pnictogen bonds in infinite molecular chains by electronic structure theory.

Science.gov (United States)

George, Janine; Deringer, Volker L; Dronskowski, Richard

2014-05-01

Halogen bonds (XBs) are intriguing noncovalent interactions that are frequently being exploited for crystal engineering. Recently, similar bonding mechanisms have been proposed for adjacent main-group elements, and noncovalent "chalcogen bonds" and "pnictogen bonds" have been identified in crystal structures. A fundamental question, largely unresolved thus far, is how XBs and related contacts interact with each other in crystals; similar to hydrogen bonding, one might expect "cooperativity" (bonds amplifying each other), but evidence has been sparse. Here, we explore the crucial step from gas-phase oligomers to truly infinite chains by means of quantum chemical computations. A periodic density functional theory (DFT) framework allows us to address polymeric chains of molecules avoiding the dreaded "cluster effects" as well as the arbitrariness of defining a "large enough" cluster. We focus on three types of molecular chains that we cut from crystal structures; furthermore, we explore reasonable substitutional variants in silico. We find evidence of cooperativity in chains of halogen cyanides and also in similar chalcogen- and pnictogen-bonded systems; the bonds, in the most extreme cases, are amplified through cooperative effects by 79% (I···N), 90% (Te···N), and 103% (Sb···N). Two experimentally known organic crystals, albeit with similar atomic connectivity and XB characteristics, show signs of cooperativity in one case but not in another. Finally, no cooperativity is observed in alternating halogen/acetone and halogen/1,4-dioxane chains; in fact, these XBs weaken each other by up to 26% compared to the respective gas-phase dimers.

High-energy-density hydrogen-halogen fuel cells for advanced military applications

International Nuclear Information System (INIS)

Balko, E.N.; McElroy, J.F.

1981-01-01

It is pointed out that hydrogen-halogen fuel cell systems are particularly suited for an employment as ground power sources for military applications. The large cell potential and reversible characteristics of the H 2 Cl 2 and H 2 Br 2 couples permit high energy storage density and efficient energy conversion. When used as flow batteries, the fluid nature of the reactants in the hydrogen-halogen systems has several advantages over power sources which involve solid phases. Very deep discharge is possible without degradation of subsequent performance, and energy storage capacity is limited only by the external reactant storage volume. Very rapid chemical recharging is possible through replenishment of the reactant supply. A number of H 2 Cl 2 and H 2 Br 2 fuel cell systems have been studied. These systems use the same solid polymer electrolyte (SPE) cell technology originally developed for H2/O2 fuel cells. The results of the investigation are illustrated with the aid of a number of graphs

Organic halogen compounds and surface water pollution; Composti organoalogenati alifatici e contaminazione delle acque superficiali

Energy Technology Data Exchange (ETDEWEB)

Cocchioni, M.; Pellegrini, M. G.; Grappasonni, I.; Nacciarriti, L.; Bernacchia, G. [Camerino, Univ. (Italy). Dipt. di Scienze Igienistiche e Sanitarie-Ambientali

1997-03-01

A brief review of the effects of halogenated organic compounds on the fluvial ecosystem is followed by results from a detailed monitoring of these substances in all the Marches Region rivers. The results show generally modest concentrations, except for sporadic peaks for chloroform. Sites revealing significant concentrations of halogenated organic compounds also manifested a worsening of the biological quality of the waters with lessening of E.B.I. Attention is drawn to the negative effects of indiscriminate chlorination of purification plant outputs, as this practice often fails to resolve infective problems and in itself adds toxicity to the watercourse.

Impact of bromide on halogen incorporation into organic moieties in chlorinated drinking water treatment and distribution systems.

Science.gov (United States)

Tan, J; Allard, S; Gruchlik, Y; McDonald, S; Joll, C A; Heitz, A

2016-01-15

The impact of elevated bromide concentrations (399 to 750 μg/L) on the formation of halogenated disinfection by-products (DBPs), namely trihalomethanes, haloacetic acids, haloacetonitriles, and adsorbable organic halogen (AOX), in two drinking water systems was investigated. Bromine was the main halogen incorporated into all of the DBP classes and into organic carbon, even though chlorine was present in large excess to maintain a disinfectant residual. Due to the higher reactivity of bromine compared to chlorine, brominated DBPs were rapidly formed, followed by a slower increase in chlorinated DBPs. Higher bromine substitution and incorporation factors for individual DBP classes were observed for the chlorinated water from the groundwater source (lower concentration of dissolved organic carbon (DOC)), which contained a higher concentration of bromide, than for the surface water source (higher DOC). The molar distribution of adsorbable organic bromine to chlorine (AOBr/AOCl) for AOX in the groundwater distribution system was 1.5:1 and almost 1:1 for the surface water system. The measured (regulated) DBPs only accounted for 16 to 33% of the total organic halogen, demonstrating that AOX measurements are essential to provide a full understanding of the formation of halogenated DBPs in drinking waters. In addition, the study demonstrated that a significant proportion (up to 94%) of the bromide in source waters can be converted AOBr. An evaluation of AOBr and AOCl through a second groundwater treatment plant that uses conventional treatment processes for DOC removal produced 70% of AOX as AOBr, with 69% of the initial source water bromide converted to AOBr. Exposure to organobromine compounds is suspected to result in greater adverse health consequences than their chlorinated analogues. Therefore, this study highlights the need for improved methods to selectively reduce the bromide content in source waters. Copyright © 2015 Elsevier B.V. All rights reserved.

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1979-February 14, 1980

Energy Technology Data Exchange (ETDEWEB)

Rack, E.P.

1980-02-01

The program consists of six interrelated areas: (1) Reactions of iodine with alkenes and alkynes activated by radiative neutron capture and isomeric transition in low pressure gaseous systems employing additives and rare gas moderators, high pressure, and liquid systems. Special attention was given to the reactivity of excited complex formation and structural effects of electrophilic iodine attack on various pi-bond systems. (2) The gas-to-condensed phase transition in halogen high energy chemistry. Current interest involves the study of caging effects of an ice lattice on recombination reactions involving neutron-irradiated frozen aqueous solutions of halogenated organic and biochemical solutes in order to learn more about kinetic energy effects, halogen size, solute molecule size, steric effects and hydrogen bonding within an ice lattice cage. (3) Systematics of halogen hot atom reactions. The reactions of /sup 80m/Br, /sup 80/Br, /sup 82m/Br + /sup 82/Br, /sup 82/Br, /sup 82/Br, /sup 128/I, /sup 130/I, and /sup 130m/I + /sup 130/I activated by radiative neutron capture or isomeric transition in hydrocarbons and halo-substituted alkanes in low pressure and high pressure gaseous systems employing additives and rare gas moderators are currently being studied. (4) Mathematical and computer simulation studies of caging events within an ice lattice are being investigated. (5) At Brookhaven National Laboratory, cyclotron-produced chlorine and fluorine hot atoms substitution reactions with molecules possessing a single chiral center are under investigation to determine the role of hot atom kinetic energy, halogen atom, enantioner structure, steric effects and phase on the extent of substitution by retention of configuration or by Walden inversion. (6) The applications of high energy techniques and concepts to neutron activation analysis for trace element determinations in biological systems was continued.

Effects of halogenated aromatics/aliphatics and nitrogen(N)-heterocyclic aromatics on estimating the persistence of future pharmaceutical compounds using a modified QSAR model.

Science.gov (United States)

Lim, Seung Joo; Fox, Peter

2014-02-01

The effects of halogenated aromatics/aliphatics and nitrogen(N)-heterocyclic aromatics on estimating the persistence of future pharmaceutical compounds were investigated using a modified half life equation. The potential future pharmaceutical compounds investigated were approximately 2000 pharmaceutical drugs currently undergoing the United States Food and Drug Administration (US FDA) testing. EPI Suite (BIOWIN) model estimates the fates of compounds based on the biodegradability under aerobic conditions. While BIOWIN considered the biodegradability of a compound only, the half life equation used in this study was modified by biodegradability, sorption and cometabolic oxidation. It was possible that the potential future pharmaceutical compounds were more accurately estimated using the modified half life equation. The modified half life equation considered sorption and cometabolic oxidation of halogenated aromatic/aliphatics and nitrogen(N)-heterocyclic aromatics in the sub-surface, while EPI Suite (BIOWIN) did not. Halogenated aliphatics in chemicals were more persistent than halogenated aromatics in the sub-surface. In addition, in the sub-surface environment, the fates of organic chemicals were much more affected by halogenation in chemicals than by nitrogen(N)-heterocyclic aromatics. © 2013.

Nano-scale patterning on sulfur terminated GaAs (0 0 1) surface by scanning tunneling microscope

International Nuclear Information System (INIS)

Yagishita, Yuki; Toda, Yusuke; Hirai, Masakazu; Fujishiro, Hiroki Inomata

2004-01-01

We perform nano-scale patterning on a sulfur (S) terminated GaAs (0 0 1) surface by a scanning tunneling microscope (STM) in ultra-high vacuum (UHV). A multi-layer of S deposited by using (NH 4 ) 2 S x solution is changed to a mono-layer after annealing at 560 deg. C for 15 h, which terminates the GaAs (0 0 1) surface. Groove structures with about 0.23 nm in depth and about 5 nm in width are patterned successfully on the S-terminated surface. We investigate dependences of both depth and width of the patterned groove on the tunneling current and the scanning speed of tip. It is observed that topmost S atoms are extracted together with first-layer Ga atoms, because of the larger binding energy of S-Ga bond

Cellular effects of halogen blue light from dental curing unit

International Nuclear Information System (INIS)

Trosic, I.; Pavicic, I.; Jukic, S.

2008-01-01

Full text: Halogen curing lights are the most frequently used polymerization source in dental offices. Light-cured bonding systems have become increasingly popular among clinicians because they offer a number of advantages over self-cured adhesives. The effort to increase polymerization quality releases the commercially available high power light density dental curing units. Emitted visible blue light belongs to the range of nonionizing radiation. Common concern in both, patients and dentist grows with regard to the unfavorable effects on the pulp tissue. The aim of study was to evaluate the time and dose dependence effect of halogen light curing unit (Elipar TriLight, ESPE Dental AG, Germany) at the disposed condition modes in vitro. A quartz-tungsten-halogen light source emits radiation of the wavelengths between 400 and 515 nm. This halogen blue light source operates in the three illumination modes, medium (M), exponential (E) and standard (S), and five illumination times. The total irradiance or the light intensity was measured by the light intensity control area on the control panel of device and mean light intensity given by manufacturer was 800 m W/cm 2 . Continuous culture of V79 cells was illuminated in triplicate. The influence of medium mode (M), exponential (E) and standard (S) illumination during 20, 40 and 80 sec on the cell viability, colony forming ability and proliferation of V79 cell culture was investigated. Trypan blue exclusion test was used to determine cell viability, both, in the treated and control cell samples. Colony forming ability was assessed for each exposure time and mode by colony count on post-exposure day 7. Cell proliferation was determined by cell counts for each time and mode of exposure during five post-exposure days. Statistical difference were determined at p<0.05 (Statistica 7.0, StatSoft Inc., USA). Viability of cells was not affected by blue light in view of exposure time and modes. Regardless to exposure or illumination

Structural study of some halogen oxyfluorides

International Nuclear Information System (INIS)

Tantot, Georges.

1976-12-01

Some halogen oxyfluorides are studied from a structural point of view by vibrational spectroscopy and nuclear magnetic resonance. Force constant and molecular orbital calculations are added to the experimental data. The pyramidal shape of ClO 2 F under its three physical states is confirmed. In the gas and liquid phases an intermolecular association is observed. A similar interaction takes place in ClOF 3 . ClO 3 F has only a solid state transition above 10K. The structures of ClO 2 F and KBrO 2 F 2 are partly determined. The theoretical calculations are well correlated with the experimental data. They suggest a major influence of the ligands [fr

Induction and prevention of micronuclei and chromosomal aberrations in cultured human lymphocytes exposed to the light of halogen tungsten lamps.

Science.gov (United States)

D'Agostini, F; Caimo, A; De Filippi, S; De Flora, S

1999-07-01

Previous studies have shown that the light emitted by halogen tungsten lamps contains UV radiation in the UV-A, UV-B and UV-C regions, induces mutations and irreparable DNA damage in bacteria, enhances the frequency of micronuclei in cultured human lymphocytes and is potently carcinogenic to the skin of hairless mice. The present study showed that the light emitted by an uncovered, traditional halogen lamp induces a significant, dose-related and time-related increase not only in micronuclei but also in chromosome-type aberrations, such as breaks, and even more in chromatid-type aberrations, such as isochromatid breaks, exchanges and isochromatid/chromatid interchanges, all including gaps or not, in cultured human lymphocytes. All these genotoxic effects were completely prevented by shielding the same lamp with a silica glass cover, blocking UV radiation. A new model of halogen lamp, having the quartz bulb treated in order to reduce the output of UV radiation, was considerably less genotoxic than the uncovered halogen lamp, yet induction of chromosomal alterations was observed at high illuminance levels.

High power light emitting diode (LED) arrays versus halogen light polymerization of oral biomaterials: Barcol hardness, compressive strength and radiometric properties.

Science.gov (United States)

Mills, Robin W; Uhl, Alexander; Blackwell, Gordon B; Jandt, Klaus D

2002-07-01

The clinical performance of light polymerized dental composites is greatly influenced by the quality of the light curing unit (LCU) used. Commonly used halogen LCUs have some specific drawbacks such as decreasing light output with time. This may result in a low degree of monomer conversion of the composites with negative clinical implications. Previous studies have shown that blue light emitting diode (LED) LCUs have the potential to polymerize dental composites without having the drawbacks of halogen LCUs. Since these studies were carried out LED technology has advanced significantly and commercial LED LCUs are now becoming available. This study investigates the Barcol hardness as a function of depth, and the compressive strength of dental composites that had been polymerized for 40 or 20s with two high power LED LCU prototypes, a commercial LED LCU, and a commercial halogen LCU. In addition the radiometric properties of the LCUs were characterized. The two high power prototype LED LCUs and the halogen LCU showed a satisfactory and similar hardness-depth performance whereas the hardness of the materials polymerized with the commercial LED LCU rapidly decreased with sample depth and reduced polymerization time (20 s). There were statistically significant differences in the overall compressive strengths of composites polymerized with different LCUs at the 95% significance level (p = 0.0016) with the two high power LED LCU prototypes and the halogen LCU forming a statistically homogenous group. In conclusion, LED LCU polymerization technology can reach the performance level of halogen LCUs. One of the first commercial LED LCUs however lacked the power reserves of the high power LED LCU prototypes.

Four-terminal circuit element with photonic core

Science.gov (United States)

Sampayan, Stephen

2017-08-29

A four-terminal circuit element is described that includes a photonic core inside of the circuit element that uses a wide bandgap semiconductor material that exhibits photoconductivity and allows current flow through the material in response to the light that is incident on the wide bandgap material. The four-terminal circuit element can be configured based on various hardware structures using a single piece or multiple pieces or layers of a wide bandgap semiconductor material to achieve various designed electrical properties such as high switching voltages by using the photoconductive feature beyond the breakdown voltages of semiconductor devices or circuits operated based on electrical bias or control designs. The photonic core aspect of the four-terminal circuit element provides unique features that enable versatile circuit applications to either replace the semiconductor transistor-based circuit elements or semiconductor diode-based circuit elements.

Quadrupole coupling constants and isomeric Moessbauer shifts for halogen-containing gold, platinum, niobium, tantalum and antimony compounds

International Nuclear Information System (INIS)

Poleshchuk, O. K.; Branchadell, V.; Ritter, R. A.; Fateev, A. V.

2008-01-01

We have analyzed by means of Density functional theory calculations the nuclear quadrupole coupling constants of a range of gold, antimony, platinum, niobium and tantalum compounds. The geometrical parameters and halogen nuclear quadrupole coupling constants obtained by these calculations substantially corresponded to the data of microwave and nuclear quadrupole resonance spectroscopy. An analysis of the quality of the calculations that employ pseudo-potentials and all-electron basis sets for the halogen compounds was carried out. The zero order regular approximation (ZORA) method is shown to be a viable alternative for the calculation of halogen coupling constants in molecules. In addition, the ZORA model, in contrast to the pseudo-potential model, leads to realistic values of all metal nuclear quadrupole coupling constants. From Klopman's approach, it follows that the relationship between the electrostatic bonding and covalent depends on the nature of the central atom. The results on Moessbauer chemical shifts are also in a good agreement with the coordination number of the central atom.

Quadrupole coupling constants and isomeric Moessbauer shifts for halogen-containing gold, platinum, niobium, tantalum and antimony compounds

Energy Technology Data Exchange (ETDEWEB)

Poleshchuk, O. K., E-mail: poleshch@tspu.edu.ru [Tomsk State Pedagogical University (Russian Federation); Branchadell, V. [Universitat Autonoma de Barcelona, Departament de Quimica (Spain); Ritter, R. A.; Fateev, A. V. [Tomsk State Pedagogical University (Russian Federation)

2008-01-15

We have analyzed by means of Density functional theory calculations the nuclear quadrupole coupling constants of a range of gold, antimony, platinum, niobium and tantalum compounds. The geometrical parameters and halogen nuclear quadrupole coupling constants obtained by these calculations substantially corresponded to the data of microwave and nuclear quadrupole resonance spectroscopy. An analysis of the quality of the calculations that employ pseudo-potentials and all-electron basis sets for the halogen compounds was carried out. The zero order regular approximation (ZORA) method is shown to be a viable alternative for the calculation of halogen coupling constants in molecules. In addition, the ZORA model, in contrast to the pseudo-potential model, leads to realistic values of all metal nuclear quadrupole coupling constants. From Klopman's approach, it follows that the relationship between the electrostatic bonding and covalent depends on the nature of the central atom. The results on Moessbauer chemical shifts are also in a good agreement with the coordination number of the central atom.

Research on information security system of waste terminal disposal process

Science.gov (United States)

Zhou, Chao; Wang, Ziying; Guo, Jing; Guo, Yajuan; Huang, Wei

2017-05-01

Informatization has penetrated the whole process of production and operation of electric power enterprises. It not only improves the level of lean management and quality service, but also faces severe security risks. The internal network terminal is the outermost layer and the most vulnerable node of the inner network boundary. It has the characteristics of wide distribution, long depth and large quantity. The user and operation and maintenance personnel technical level and security awareness is uneven, which led to the internal network terminal is the weakest link in information security. Through the implementation of security of management, technology and physics, we should establish an internal network terminal security protection system, so as to fully protect the internal network terminal information security.

Allergic contact dermatitis due to highly reactive halogenated compounds

Energy Technology Data Exchange (ETDEWEB)

Pickering, F C; Ive, F A

1983-11-01

Ten cases of dermatitis in a fine organic chemicals plant are reported. These cases were all due to exposure to chemical compounds with reactive bromine or chlorine atoms. This type of chemical is always extremely irritant, but evidence is put forward to suggest that these cases were the result of allergic sensitization. Chemicals with reactive halogen atoms should always be handled with extreme care and patch testing should be approached with caution.

Layering in peralkaline magmas, Ilímaussaq Complex, S Greenland

Science.gov (United States)

Hunt, Emma J.; Finch, Adrian A.; Donaldson, Colin H.

2017-01-01

The peralkaline to agpaitic Ilímaussaq Complex, S. Greenland, displays spectacular macrorhythmic (> 5 m) layering via the kakortokite (agpaitic nepheline syenite), which outcrops as the lowest exposed rocks in the complex. This study applies crystal size distribution (CSD) analyses and eudialyte-group mineral chemical compositions to study the marker horizon, Unit 0, and the contact to the underlying Unit - 1. Unit 0 is the best-developed unit in the kakortokites and as such is ideal for gaining insight into processes of crystal formation and growth within the layered kakortokite. The findings are consistent with a model whereby the bulk of the black and red layers developed through in situ crystallisation at the crystal mush-magma interface, whereas the white layer developed through a range of processes operating throughout the magma chamber, including density segregation (gravitational settling and flotation). Primary textures were modified through late-stage textural coarsening via grain overgrowth. An open-system model is proposed, where varying concentrations of halogens, in combination with undercooling, controlled crystal nucleation and growth to form Unit 0. Our observations suggest that the model is applicable more widely to the layering throughout the kakortokite series and potentially other layered peralkaline/agpaitic rocks around the world.

Competition between Halogen, Hydrogen and Dihydrogen Bonding in Brominated Carboranes

Czech Academy of Sciences Publication Activity Database

Fanfrlík, Jindřich; Holub, Josef; Růžičková, Z.; Řezáč, Jan; Lane, P. D.; Wann, D. A.; Hnyk, Drahomír; Růžička, A.; Hobza, Pavel

2016-01-01

Roč. 17, č. 21 (2016), s. 3373-3376 ISSN 1439-4235 R&D Projects: GA ČR(CZ) GBP208/12/G016; GA ČR(CZ) GA15-05677S Institutional support: RVO:61388963 ; RVO:61388980 Keywords : bromine * carboranes * halogen bonds * sigma holes * X-ray crystal structure Subject RIV: CF - Physical ; Theoretical Chemistry; CA - Inorganic Chemistry (UACH-T) Impact factor: 3.075, year: 2016

Strength and Character of Halogen Bonds in Protein-Ligand Complexes

Czech Academy of Sciences Publication Activity Database

Riley, Kevin Eugene; Hobza, Pavel

2011-01-01

Roč. 11, č. 10 (2011), s. 4272-4278 ISSN 1528-7483 R&D Projects: GA MŠk LC512 Grant - others:Research and Development for Innovations of European Social Fund(XE) CZ.1.05/2.1.00/03.0058 Institutional research plan: CEZ:AV0Z40550506 Keywords : halogen bond * protein-ligand complexes * calculations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.720, year: 2011

Atomic control of substrate termination and heteroepitaxial growth of SrTiO sub 3 /LaAlO sub 3 films

CERN Document Server

Kim, D W; Choi, C; Lim, K D; Noh, T W; Lee, D R; Park, J H; Lee, K B

2000-01-01

The roles of substrate termination in the growth behaviors of SrTiO sub 3 (STO) films were investigated. With heat treatment and an atomic layer deposition technique, LaAlO sub 3 (LAO) substrates with two kinds of terminations, i.e., LaO- and AlO sub 2 -terminated ones, could be prepared. On top of them STO films were grown by using laser molecular beam epitaxy. In the case of the STO/LaO-LAO film, a transition from layer-by-layer growth to island growth was observed after growth of about 10 monolayers (ML). On the other hand, the STO/AlO sub 2 -LAO film could be grown in a layer-by-layer mode with a flat surface up to 40 ML. We suggest that defects induced by charge compensation influence the strain states and the physical properties of oxide heterostructures significantly.

A halogen-free synthesis of gold nanoparticles using gold(III) oxide

International Nuclear Information System (INIS)

Sashuk, Volodymyr; Rogaczewski, Konrad

2016-01-01

Gold nanoparticles are one of the most used nanomaterials. They are usually synthesized by the reduction of gold(III) chloride. However, the presence of halide ions in the reaction mixture is not always welcome. In some cases, these ions have detrimental influence on the morphology and structure of resulting nanoparticles. Here, we present a simple and halogen-free procedure to prepare gold nanoparticles by reduction of gold(III) oxide in neat oleylamine. The method provides the particles with an average size below 10 nm and dispersity of tens of percent. The process of nanoparticle formation was monitored using UV–Vis spectroscopy. The structure and chemical composition of the nanoparticles was determined by SEM, XPS and EDX. We also proposed the mechanism of reduction of gold(III) oxide based on MS, IR and NMR data. Importantly, the synthetic protocol is general and applicable for the preparation of other coinage metal nanoparticles from the corresponding metal oxides. For instance, we demonstrated that the absence of halogen enables efficient alloying of metals when preparing gold–silver bimetallic nanoparticles.

Halogen doping of II-VI semiconductors during molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Waag, A.; Litz, Th.; Fischer, F.; Heinke, H.; Scholl, S.; Hommel, D.; Landwehr, G. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Bilger, G. (Zentrum fuer Sonnenenergie und Wasserstoff-Forschung, Stuttgart (Germany))

1994-04-14

Results on the halogen doping of CdTe, (CdMn)Te as well as (CdMg)Te thin films and quantum well structures are reported. The structures were grown by molecular beam epitaxy. The samples have been investigated by Van der Pauw, photoconductivity, X-ray diffraction, XPS and SIMS measurements. ZnCl[sub 2] and ZnBr[sub 2] have been used as dopant sources. Free carrier concentrations at room temperature above 10[sup 18] cm[sup -3] can easily be achieved for CdTe for a wide range of Cd/Te flux ratios and substrate temperatures. In the ternary alloys, the free carrier concentration decreases drastically with increasing x-values, despite a constant incorporation of the dopant species. In addition, persistent photoconductivity has been observed in n-type doped ternary thin films at low temperatures. The decrease of the free carrier concentration with x-value is common to other wide-gap ternary alloys, and the reason for it is discussed in the frame of DX-like deep donor impurities in ternary II-VI compounds. In first experiments on planar halogen doping of CdTe, a doping level of 5x10[sup 18] cm[sup -3] could be reached in the doped regions, the highest value ever reported for CdTe. A clear influence of dopant incorporation on the structural quality of CdTe thin films has been seen even for dopant concentrations of as low as 10[sup 18] cm[sup -3]. The FWHM of the rocking curves decreased by a factor of 2 with increasing dopant incorporation. SIMS as well as XPS measurements demonstrate that the Cl/Zn and Br/Zn ratio in the doped films is 2/1, but no chemical shift corresponding to Zn-Cl or Zn-Br bonds could be detected. A model for the incorporation of the halogens is proposed on the basis of these results

Flue gas corrosion through halogen compounds in fuel gas

Energy Technology Data Exchange (ETDEWEB)

Eisenmann, R

1987-04-01

The halogens of chlorine and fluorine greatly influence the corrosion speed of metal materials. If small quantities of chlorinated and/or fluorinated hydrocarbons are present in fuel gas like in landfill gas, they must not result in enhanced corrosion of gas appliances. Data from literature and the initial results of tests run by the author indicate that quantities at about 10 mg/cbm (in terms of chlorine) can be assumed not to cause any noticeable acceleration of corrosion speed.

Environmental and economic implications of a shift to halogen-free printed wiring boards

Energy Technology Data Exchange (ETDEWEB)

Bergendahl, C.G.; Johansson, G.; Zackrisson, M. [IVF Industrial Research and Development Corp., Moelndal (Sweden); Lichtenvort, K. [Technical Univ. of Berlin (Germany); Nyyssoenen, J. [Aspocomp Oy, Salo (Finland)

2004-07-01

The 'Restriction of Hazardous Substances Directive' (RoHS) and the 'Waste from Electrical and Electronic Equipment Directive' (WEEE) enforced by the European Commission require new materials and processes to be implemented in the production of electrical and electronic equipment (EEE). In response to this, the project grEEEn (Cost Management System for greening Electrical and Electronic Equipment) was defined and carried out within the 5th framework programme of the EU. This paper presents the grEEEn method and the outcome of applying the method on a case study. The study addressed the material shift in printed wiring boards (PWBs), from the traditional FR4 material containing halogenated flame retardants to halogen-free FR4 materials. The paper presents the product, process and scenario modelling and the results from analysing costs, environmental profile and legal compliance. (orig.)

Optical modulation in nematic phase of halogen substituted hydrogen bonded liquid crystals

Science.gov (United States)

Vijayakumar, V. N.; Madhu Mohan, M. L. N.

2012-01-01

A series of halogen-substituted hydrogen-bonded liquid crystalline complexes have been designed and synthesised. A successful attempt has been made to form complementary hydrogen bonding between the dodecyloxy benzoic acid (12BAO) and halogen-substituted benzoic acids and the physical properties exhibited by the individual complexes are studied. The complexes obtained are analysed by polarising optical microscope (POM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and dielectric studies. The formation of complementary hydrogen bond is confirmed through FTIR spectra. An interesting feature of this series is the observation of a field-induced transition (FiT) in nematic phase. Another interesting phenomenon is the observation of a new smectic X phase (worm-like texture) in all the synthesised complexes. Dielectric relaxation studies in the smectic C phase of these hydrogen bonded complexes along with the Arrhenius and the Cole-Cole plots are discussed. Optical tilt angle in smectic C phase and the corresponding fitted data analysis concur with the Mean field theory prediction.

Hydrogenated and halogenated blue phosphorene as Dirac materials: A first principles study

International Nuclear Information System (INIS)

Sun, Minglei; Wang, Sake; Yu, Jin; Tang, Wencheng

2017-01-01

Highlights: • The fully hydrogenated and halogenated blue phosphorenes are 2D Dirac materials. • The Dirac cone in fluorinated and iodinated blue phosphorenes lies exactly at the Fermi level. • The mass density of hydrogenated and fluorinated blue phosphorenes is rather small. - Abstract: Using first-principles calculations, we systematically investigate the structures and electronic properties of fully hydrogenated and halogenated blue phosphorene (P_2X_2). All these systems possess Dirac cone at high-symmetry K point, which are mainly contributed by P s p_x p_y orbitals. The Dirac cone in P_2F_2 and P_2I_2 systems lies exactly at the Fermi level. Formation energy analysis denotes that all the systems are energetically stable except P_2I_2. The mass density for P_2H_2 and P_2F_2 systems is rather small. Our calculations proposed that these systems, especially P_2F_2 system, have great potential applications in future nanoelectronics.

Negative atomic halogens incident on argon and molecular nitrogen: electron detachment studies

International Nuclear Information System (INIS)

Jalbert, G; Medina, A; Magalhaes, S D; Wolff, W; Barros, A L F de; Carrilho, P; Rocha, A B; Faria, N V de Castro

2007-01-01

During the last years we have measured total detachment cross sections of atomic and cluster anions colliding with gases in the velocity range of 0.2 to 1.8 a.u. In particular, we measured negative atomic halogens incident on argon and molecular nitrogen. These last data are for the first time analyzed using the simple semi-classical model that we have developed. For that purpose, the values of elastic plus inelastic cross sections for impact of free electrons on Ar and N 2 , the latter showing a shape resonance, convoluted with the anion's outermost electron momentum distribution yielded the overall shape of the anion cross sections. Inclusion of a velocity independent additive term, interpreted as an effective area of the collision region, led to accurate absolute cross section values. The high affinity of the halogens and the existence of a not well described resonance in the e-N 2 collision, are characteristics that may be used to delimit the scope and validity of the model

A simple and automated sample preparation system for subsequent halogens determination: Combustion followed by pyrohydrolysis.

Science.gov (United States)

Pereira, L S F; Pedrotti, M F; Vecchia, P Dalla; Pereira, J S F; Flores, E M M

2018-06-20

A simple and automated system based on combustion followed by a pyrohydrolysis reaction was proposed for further halogens determination. This system was applied for digestion of soils containing high (90%) and also low (10%) organic matter content for further halogens determination. The following parameters were evaluated: sample mass, use of microcrystalline cellulose and heating time. For analytes absorption, a diluted alkaline solution (6 mL of 25 mmol L -1  NH 4 OH) was used in all experiments. Up to 400 mg of soil with high organic matter content and 100 mg of soil with low organic matter content (mixed with 400 mg of cellulose) could be completely digested using the proposed system. Quantitative results for all halogens were obtained using less than 12 min of sample preparation step (about 1.8 min for sample combustion and 10 min for pyrohydrolysis). The accuracy was evaluated using a certified reference material of coal and spiked samples. No statistical difference was observed between the certified values and results obtained by the proposed method. Additionally, the recoveries obtained using spiked samples were in the range of 98-103% with relative standard deviation values lower than 5%. The limits of quantification obtained for F, Cl, Br and I for soil with high (400 mg of soil) and low (100 mg of soil) organic matter were in the range of 0.01-2 μg g -1 and 0.07-59 μg g -1 , respectively. The proposed system was considered as a simple and suitable alternative for soils digestion for further halogens determination by ion chromatography and inductively coupled plasma mass spectrometry techniques. Copyright © 2018 Elsevier B.V. All rights reserved.

Three-terminal resistive switching memory in a transparent vertical-configuration device

International Nuclear Information System (INIS)

Ungureanu, Mariana; Llopis, Roger; Casanova, Fèlix; Hueso, Luis E.

2014-01-01

The resistive switching phenomenon has attracted much attention recently for memory applications. It describes the reversible change in the resistance of a dielectric between two non-volatile states by the application of electrical pulses. Typical resistive switching memories are two-terminal devices formed by an oxide layer placed between two metal electrodes. Here, we report on the fabrication and operation of a three-terminal resistive switching memory that works as a reconfigurable logic component and offers an increased logic density on chip. The three-terminal memory device we present is transparent and could be further incorporated in transparent computing electronic technologies

Phosphorylated lignin as a halogen-free flame retardant additive for epoxy composites

Science.gov (United States)

Gamini P. Mendis; Sydney G. Weiss; Matthew Korey; Charles R. Boardman; Mark Dietenberger; Jeffrey P. Youngblood; John A. Howarter

2016-01-01

Sustainable, non-halogenated flame retardants are desired for a variety of industry applications. Lignin, as an industrially processed wood derivative, has been examined as a potential sustainable flame retardant additive to polymer systems. Here, the lignin is phosphorylated using a pyridine-catalysed esterification reaction with diphenyl phosphoryl chloride to...

The distribution of chandelier cell axon terminals that express the GABA plasma membrane transporter GAT-1 in the human neocortex.

Science.gov (United States)

Inda, M C; Defelipe, J; Muñoz, A

2007-09-01

Chandelier cells represent a unique type of cortical GABAergic interneuron whose axon terminals (Ch-terminals) form synapses exclusively with the axon initial segments of pyramidal cells. In this study, we have used immunocytochemistry for the high-affinity plasma membrane transporter-1 (GAT-1) to analyze the distribution and density of Ch-terminals in various cytoarchitectonic and functional areas of the human neocortex. The lowest density of GAT-1-immuoreactive (-ir) Ch-terminals was detected in the primary and secondary visual (areas 17 and 18) and in the somatosensory areas (areas 3b and 1). In contrast, an intermediate density was observed in the motor area 4 and the associative frontolateral areas 45 and 46, whereas the associative frontolateral areas 9 and 10, frontal orbitary areas 11, 12, 13, 14, and 47, associative temporal areas 20, 21, 22, and 38, and cingulate areas 24 and 32 displayed the highest density of GAT-1-ir Ch-terminals. Despite these differences, the laminar distribution of GAT-1-ir Ch-terminals was similar in most cortical areas. Hence, the highest density of this transporter was observed in layer II, followed by layers III, V, VI, and IV. In most cortical areas, the density of GAT-1-ir Ch-terminals was positively correlated with the neuronal density, although a negative correlation was detected in layer III across all cortical areas. These results indicate that there are substantial differences in the distribution and density of GAT-1-ir Ch-terminals between areas and layers of the human neocortex. These differences might be related to the different functional attributes of the cortical regions examined.

Diversity of band gap and photoluminescence properties of lead halide perovskite: A halogen-dependent spectroscopic study

Science.gov (United States)

Yu, Wenlei; Jiang, Yunfeng; Zhu, Xiuwei; Luo, Chunhua; Jiang, Kai; Chen, Liangliang; Zhang, Juan

2018-05-01

The effects of halogen substitution on microstructure, optical absorption, and phonon modes for perovskite CH3NH3PbX3 (MAPbX3, X = I/Br/Cl) films grown on FTO substrates have been investigated. The X-ray diffraction analysis exhibited good crystallization, and the strong diffraction peak assigned to (1 0 0) c for X = Br/Cl shifted toward a higher angle compared to (1 1 0) t of MAPbI3. Band-gap tuning from 1.63 to 2.37 to 3.11 eV in the I-Br-Cl series can be found due to the halogen effects. These energy values closely match the positions of peak determined from photoluminescence experiments. The remarkable absorption dip and emission peak appear for the MAPbBr3, suggesting higher crystallinity under the same preparation conditions. The wavenumbers of main IR-vibrations slightly decrease with ionic radius of the halogen increasing (in the order of Cl-Br-I), which related to the increasing polarizability. These results provide important progress towards the understanding of the halide role in the realization of high performance MAPbX3-based solar cells.

Substrate-induced magnetism in epitaxial graphene buffer layers.

Science.gov (United States)

Ramasubramaniam, A; Medhekar, N V; Shenoy, V B

2009-07-08

Magnetism in graphene is of fundamental as well as technological interest, with potential applications in molecular magnets and spintronic devices. While defects and/or adsorbates in freestanding graphene nanoribbons and graphene sheets have been shown to cause itinerant magnetism, controlling the density and distribution of defects and adsorbates is in general difficult. We show from first principles calculations that graphene buffer layers on SiC(0001) can also show intrinsic magnetism. The formation of graphene-substrate chemical bonds disrupts the graphene pi-bonds and causes localization of graphene states near the Fermi level. Exchange interactions between these states lead to itinerant magnetism in the graphene buffer layer. We demonstrate the occurrence of magnetism in graphene buffer layers on both bulk-terminated as well as more realistic adatom-terminated SiC(0001) surfaces. Our calculations show that adatom density has a profound effect on the spin distribution in the graphene buffer layer, thereby providing a means of engineering magnetism in epitaxial graphene.

Natural elimination of volatile halogenated hydrocarbons from the environment

Energy Technology Data Exchange (ETDEWEB)

Harress, H.M.; Grathwohl, P.; Torunski, H.

1987-01-01

Recently carried out field investigations of groundwater contaminations with volatile halogenated hydrocarbons have shown evidence of natural elimination of these hazardous substances. This elimination effects is rare and observed in connection with special geological conditions. With regard to some contaminated sites, the following mechanisms for this behaviour are discussed: 1. Stripping by naturally ascending gases. 2. Sorption on soil organic matter. 3. Biodegradation. The so far compiled knowledge allowed to develop further research programmes, which are pursued in various projects.

Liquid Crystalline Dendrimers. 1. Synthesis of Five Generations of Carbosilane Liquid Crystalline Dendrimers with Terminal Cyanobiphenyl Groups

National Research Council Canada - National Science Library

Shibaev, V

1998-01-01

Using the controlled layer by layer experimental technique via reiterative sequence of chemical reactions carbosilane LC dendrimers with terminal cyanobiphenyl mesogenic groups of generations 1 - 5 were synthesized...

Tumour radiosensitization with the halogenated pyrimidines 5'-bromo-and 5'-iododeoxyuridine

Energy Technology Data Exchange (ETDEWEB)

Epstein, A.H.; Cook, J.A.; Goffman, T. (National Cancer Inst., Bethesda, MD (United States)); Glatstein, E. (Texas Univ., Dallas, TX (United States). Southwestern Medical Center)

1993-02-01

The authors review studies of the use of iododeoxyuridine (IdUrd) and bromodeoxyuridine as radiosensitizers and attempt to correlate the clinical outcome for patients treated with radiation and IdUrd with the extent of halogenated pyrimidine cellular uptake and incorporation. (U.K.).

Molecular recognition of halogen-tagged aromatic VOCs at the air-silicon interface.

Science.gov (United States)

Condorelli, Guglielmo G; Motta, Alessandro; Favazza, Maria; Gurrieri, Ettore; Betti, Paolo; Dalcanale, Enrico

2010-01-14

Selective and reversible complexation of halogen-tagged aromatic VOCs by a quinoxaline cavitand-decorated Si surface is demonstrated. The specific host-guest interactions of the Si-bonded receptors are proved to be responsible of the surface recognition properties, while extracavity non specific adsorptions are totally suppressed compared to the bulk material.

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1979-February 14, 1980

International Nuclear Information System (INIS)

Rack, E.P.

1980-02-01

The program consists of six interrelated areas: (1) Reactions of iodine with alkenes and alkynes activated by radiative neutron capture and isomeric transition in low pressure gaseous systems employing additives and rare gas moderators, high pressure, and liquid systems. Special attention was given to the reactivity of excited complex formation and structural effects of electrophilic iodine attack on various pi-bond systems. (2) The gas-to-condensed phase transition in halogen high energy chemistry. Current interest involves the study of caging effects of an ice lattice on recombination reactions involving neutron-irradiated frozen aqueous solutions of halogenated organic and biochemical solutes in order to learn more about kinetic energy effects, halogen size, solute molecule size, steric effects and hydrogen bonding within an ice lattice cage. (3) Systematics of halogen hot atom reactions. The reactions of /sup 80m/Br, 80 Br, /sup 82m/Br + 82 Br, 82 Br, 82 Br, 128 I, 130 I, and /sup 130m/I + 130 I activated by radiative neutron capture or isomeric transition in hydrocarbons and halo-substituted alkanes in low pressure and high pressure gaseous systems employing additives and rare gas moderators are currently being studied. (4) Mathematical and computer simulation studies of caging events within an ice lattice are being investigated. (5) At Brookhaven National Laboratory, cyclotron-produced chlorine and fluorine hot atoms substitution reactions with molecules possessing a single chiral center are under investigation. (6) The applications of high energy techniques and concepts to neutron activation analysis for trace elements and trace molecule determinations in biological systems was continued

The second report of the German Government to the German Bundestag about measures to protect the ozone layer

International Nuclear Information System (INIS)

1992-11-01

The second report presented by the German Government to the Bundestag about measures for the protection of the ozone layer reveals germany's international leading role in the phaseout of CFCs and halogenated hydrocarbons. In no other country in the world has such an extensive plan for withdrawing from use of substances harmful to the ozone layer been implemented. Manufacturers and users have proved, by their impressive promises of undercutting the time limits set in the ordinance on a ban on CFCs, that the cooperation principle, always placed first in environmental policy, can be successfully practised. The Montreal Protocol establishes successful international measures, backed by international law, for an abandonment of substances that are harmful to the ozone layer. (orig.) [de

Solution and solid-phase halogen and C-H hydrogen bonding to perrhenate.

Science.gov (United States)

Massena, Casey J; Riel, Asia Marie S; Neuhaus, George F; Decato, Daniel A; Berryman, Orion B

2015-01-28

(1)H NMR spectroscopic and X-ray crystallographic investigations of a 1,3-bis(4-ethynyl-3-iodopyridinium)benzene scaffold with perrhenate reveal strong halogen bonding in solution, and bidentate association in the solid state. A nearly isostructural host molecule demonstrates significant C-H hydrogen bonding to perrhenate in the same phases.

Degradation of halogenated aliphatic compounds by the ammonia- oxidizing bacterium Nitrosomonas europaea.

OpenAIRE

Vannelli, T; Logan, M; Arciero, D M; Hooper, A B

1990-01-01

Suspensions of Nitrosomonas europaea catalyzed the ammonia-stimulated aerobic transformation of the halogenated aliphatic compounds dichloromethane, dibromomethane, trichloromethane (chloroform), bromoethane, 1,2-dibromoethane (ethylene dibromide), 1,1,2-trichloroethane, 1,1,1-trichloroethane, monochloroethylene (vinyl chloride), gem-dichloroethylene, cis- and trans-dichloroethylene, cis-dibromoethylene, trichloroethylene, and 1,2,3-trichloropropane, Tetrachloromethane (carbon tetrachloride),...

Perspectives on halogen bonding and other sigma-hole interactions: Lex parsimoniae (Occam's Razor)

Czech Academy of Sciences Publication Activity Database

Politzer, P.; Riley, Kevin Eugene; Bulat, F. A.; Murray, J. S.

2012-01-01

Roč. 998, SI (2012), s. 2-8 ISSN 2210-271X Institutional research plan: CEZ:AV0Z40550506 Keywords : halogen bonding * alpha-Hole bonding * hydrogen bonding * electrostatics /polarization * dispersion * electrostatic potentials Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.139, year: 2012

PATTERN RECOGNITION STUDIES OF HALOGENATED ORGANIC COMPOUNDS USING CONDUCTING POLYMER SENSOR ARRAYS. (R825323)

Science.gov (United States)

Direct measurement of volatile and semivolatile halogenated organic compounds of environmental interest was carried out using arrays of conducting polymer sensors. Mathematical expressions of the sensor arrays using microscopic polymer network model is described. A classical, non...

Study on the dynamics of halogen elements in the agro-environment and these element`s deficiency, toxicity and environmental hazards by the application of the neutron activation analysis method

Energy Technology Data Exchange (ETDEWEB)

Yuita, Kouichi [National Inst. of Agro-Environmental Sciences, Tsukuba, Ibaraki (Japan)

1998-03-01

A neutron activation analysis method is an accurate and highly sensitive method for analyzing halogen elements (iodine, bromine and chlorine) except fluorine. It is unsubstitutable and valuable method especially for iodine (including radioactive {sup 129}I) and bromine which are present at lower levels. Halogen elements have high chemical and physiological activities and move widely in the environment. As a result, deficiency and an excess of halogen elements in plants and animals have occurred and artificial halogen compounds have caused environmental pollution in wide areas. We efficiently utilized the neutron activation analysis method and an activable tracer method to obtain valuable findings which contribute to the clarification of and measures against these actual problems and which are also concerned with the occurrence, distribution and migration of halogen elements in the environment, especially agricultural and forestry ecosystems in space and in time. (author)

Cortical layers, rhythms and BOLD signals.

Science.gov (United States)

Scheeringa, René; Fries, Pascal

2017-11-03

This review investigates how laminar fMRI can complement insights into brain function derived from the study of rhythmic neuronal synchronization. Neuronal synchronization in various frequency bands plays an important role in neuronal communication between brain areas, and it does so on the backbone of layer-specific interareal anatomical projections. Feedforward projections originate predominantly in supragranular cortical layers and terminate in layer 4, and this pattern is reflected in inter-laminar and interareal directed gamma-band influences. Thus, gamma-band synchronization likely subserves feedforward signaling. By contrast, anatomical feedback projections originate predominantly in infragranular layers and terminate outside layer 4, and this pattern is reflected in inter-laminar and interareal directed alpha- and/or beta-band influences. Thus, alpha-beta band synchronization likely subserves feedback signaling. Furthermore, these rhythms explain part of the BOLD signal, with independent contributions of alpha-beta and gamma. These findings suggest that laminar fMRI can provide us with a potentially useful method to test some of the predictions derived from the study of neuronal synchronization. We review central findings regarding the role of layer-specific neuronal synchronization for brain function, and regarding the link between neuronal synchronization and the BOLD signal. We discuss the role that laminar fMRI could play by comparing it to invasive and non-invasive electrophysiological recordings. Compared to direct electrophysiological recordings, this method provides a metric of neuronal activity that is slow and indirect, but that is uniquely non-invasive and layer-specific with potentially whole brain coverage. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Low molecular weight halogenated hydrocarbons (LMHHs) in Mediterranean sea water: Preliminary observations

International Nuclear Information System (INIS)

Elder, D.L.; Villeneuve, J.P.; Harvey, G.R.

1976-01-01

Halogenated organic compounds containing 1-3 carbon atoms are among the most extensively produced synthetic chemicals. Within this group of compounds are solvents such as chloroform, carbon tetrachloride, trichloroethane and the chlorofluoro carbons or freons which are used as refrigerants and aerosol sprays. Once produced many of these compounds are eventually released to the environment

Rearrangements in the halogenation of tetraalkylethylenes with N-halosuccinimides and tert-butyl hypochlorite

NARCIS (Netherlands)

Meijer, E.W.; Kellogg, R.M.; Wynberg, H.

1982-01-01

The reaction of N-halosuccinimides and Me3COCl with tetraalkylethylenes involves halo-cation addn. to the double bond in a fast reaction, followed by abstraction of an allylic proton, resulting in a double bond shift. Homoallylic halogenation occurs in tetraalkylethylenes which can not undergo a

Hydrogenated and halogenated blue phosphorene as Dirac materials: A first principles study

Energy Technology Data Exchange (ETDEWEB)

Sun, Minglei [School of Mechanical Engineering, Southeast University, Nanjing, Jiangsu 211189 (China); Wang, Sake [Department of Physics, Southeast University, Nanjing, Jiangsu 210096 (China); Yu, Jin [School of Materials Science and Engineering, Southeast University, Nanjing, Jiangsu 211189 (China); Tang, Wencheng, E-mail: 101000185@seu.edu.cn [School of Mechanical Engineering, Southeast University, Nanjing, Jiangsu 211189 (China)

2017-01-15

Highlights: • The fully hydrogenated and halogenated blue phosphorenes are 2D Dirac materials. • The Dirac cone in fluorinated and iodinated blue phosphorenes lies exactly at the Fermi level. • The mass density of hydrogenated and fluorinated blue phosphorenes is rather small. - Abstract: Using first-principles calculations, we systematically investigate the structures and electronic properties of fully hydrogenated and halogenated blue phosphorene (P{sub 2}X{sub 2}). All these systems possess Dirac cone at high-symmetry K point, which are mainly contributed by P s p{sub x} p{sub y} orbitals. The Dirac cone in P{sub 2}F{sub 2} and P{sub 2}I{sub 2} systems lies exactly at the Fermi level. Formation energy analysis denotes that all the systems are energetically stable except P{sub 2}I{sub 2}. The mass density for P{sub 2}H{sub 2} and P{sub 2}F{sub 2} systems is rather small. Our calculations proposed that these systems, especially P{sub 2}F{sub 2} system, have great potential applications in future nanoelectronics.

Evaluation of wear rate of dental composites polymerized by halogen or LED light curing units

Directory of Open Access Journals (Sweden)

Alaghehmand H.

2006-08-01

Full Text Available Background and Aim: Sufficient polymerization is a critical factor to obtain optimum physical properties and clinical efficacy of resin restorations. The aim of this study was to evaluate wear rates of composite resins polymerized by two different systems Light Emitting Diodes (LED to and Halogen lamps. Materials and Methods: In this laboratory study, 20 specimens of A3 Tetric Ceram composite were placed in brass molds of 2*10*10 mm dimensions and cured for 40 seconds with 1 mm distance from surface. 10 specimens were cured with LED and the other 10 were cured with Halogen unit. A device with the ability to apply force was developed in order to test the wear of composites. After storage in distilled water for 10 days, the specimens were placed in the wear testing machine. A chrome cobalt stylus with 1.12 mm diameter was applied against the specimens surfaces with a load of 2 kg. The weight of each samples before and after 5000, 10000, 20000, 40000, 80000 and 120000 cycles was measured using an electronic balance with precision of 10-4 grams. Data were analyzed using t test and paired t test. P0.05. Conclusion: Based on the results of this study, LED and halogen light curing units resulted in a similar wear rate in composite resin restorations.

Control of aliphatic halogenated DBP precursors with multiple drinking water treatment processes: Formation potential and integrated toxicity.

Science.gov (United States)

Zhang, Yimeng; Chu, Wenhai; Yao, Dechang; Yin, Daqiang

2017-08-01

The comprehensive control efficiency for the formation potentials (FPs) of a range of regulated and unregulated halogenated disinfection by-products (DBPs) (including carbonaceous DBPs (C-DBPs), nitrogenous DBPs (N-DBPs), and iodinated DBPs (I-DBPs)) with the multiple drinking water treatment processes, including pre-ozonation, conventional treatment (coagulation-sedimentation, pre-sand filtration), ozone-biological activated carbon (O 3 -BAC) advanced treatment, and post-sand filtration, was investigated. The potential toxic risks of DBPs by combing their FPs and toxicity values were also evaluated. The results showed that the multiple drinking water treatment processes had superior performance in removing organic/inorganic precursors and reducing the formation of a range of halogenated DBPs. Therein, ozonation significantly removed bromide and iodide, and thus reduced the formation of brominated and iodinated DBPs. The removal of organic carbon and nitrogen precursors by the conventional treatment processes was substantially improved by O 3 -BAC advanced treatment, and thus prevented the formation of chlorinated C-DBPs and N-DBPs. However, BAC filtration leads to the increased formation of brominated C-DBPs and N-DBPs due to the increase of bromide/DOC and bromide/DON. After the whole multiple treatment processes, the rank order for integrated toxic risk values caused by these halogenated DBPs was haloacetonitriles (HANs)≫haloacetamides (HAMs)>haloacetic acids (HAAs)>trihalomethanes (THMs)>halonitromethanes (HNMs)≫I-DBPs (I-HAMs and I-THMs). I-DBPs failed to cause high integrated toxic risk because of their very low FPs. The significant higher integrated toxic risk value caused by HANs than other halogenated DBPs cannot be ignored. Copyright © 2017. Published by Elsevier B.V.

Human factors in aviation: Terminal control area boundary conflicts

Science.gov (United States)

Monan, William P.

1989-01-01

Air-to-air conflicts in the vicinity of Terminal Control Area (TCA) boundaries were studied to obtain a better understanding of the causal dynamics of these events with particular focus on human factor issues. The study dataset consisted of 381 Instrument Flight Rules/Visual Flight Rules (IFR/VFR) traffic conflicts in airspace layers above TCA ceiling and below TCA floors; 213 reports of incursions in TCA terminal airspace by VFR aircraft, of which 123 resulted in conflicts; and an additional set of reports describing problems with Air Traffic Control (ATC) services in and around TCAs. Results and conclusions are detailed.

Crystallochemical analysis of rare-earth halogen-containing π-complexes

International Nuclear Information System (INIS)

Blatova, O.A.; Blatov, V.A.; Serezhkin, V.N.

2001-01-01

Dependence of the size of Ln atom action in coordination polyhedrons LnC n X m (X = F, Cl, Br) on its nature, coordination number, oxidation state and number of Ln-X bonds, was studied using 96 halogen-containing π-complexes of rare earth and yttrium (Ln) by way of example. A method of estimating ligand sizes in coordination sphere using the Voronoi-Dirichlet molecular polyhedrons was suggested. Influence of the ligands sizes on stability of π-complexes and presence of specific interactions in their structure was analyzed [ru

Terminal velocity of liquids and granular materials dispersed by a high explosive

Science.gov (United States)

Loiseau, J.; Pontalier, Q.; Milne, A. M.; Goroshin, S.; Frost, D. L.

2018-04-01

The explosive dispersal of a layer of solid particles or a layer of liquid surrounding a spherical high-explosive charge generates a turbulent, multiphase flow. Shock compression of the material layer during the initial acceleration may partially consolidate the material, leading to the formation of jet-like structures when the layer fragments and sheds particles upon release. Similarly, release of a shock-compressed liquid shell causes the nucleation of cavitation sites, leading to the radial breakup of the shell and the formation of jets upon expansion. In the current study, a wide variety of granular materials and liquids were explosively dispersed. The maximum terminal jet tip or shell velocity was measured using high-speed videography. Charges were constructed using thin-walled glass bulbs of various diameters and contained a central C-4 charge surrounded by the material to be dispersed. This permitted variation of the ratio of material mass to charge mass (M/C) from 4 to 300. Results indicated that material velocity broadly correlates with predictions of the Gurney model. For liquids, the terminal velocity was accurately predicted by the Gurney model. For granular materials, Gurney over-predicted the terminal velocity by 25-60%, depending on the M/C ratio, with larger M/C values exhibiting larger deficits. These deficits are explained by energy dissipation during the collapse of voids in the granular material bed. Velocity deficits were insensitive to the degree of jetting and granular material properties. Empirical corrections to the Gurney model are presented with improved agreement with the dry powder experimental velocities.

Terminal velocity of liquids and granular materials dispersed by a high explosive

Science.gov (United States)

Loiseau, J.; Pontalier, Q.; Milne, A. M.; Goroshin, S.; Frost, D. L.

2018-05-01

The explosive dispersal of a layer of solid particles or a layer of liquid surrounding a spherical high-explosive charge generates a turbulent, multiphase flow. Shock compression of the material layer during the initial acceleration may partially consolidate the material, leading to the formation of jet-like structures when the layer fragments and sheds particles upon release. Similarly, release of a shock-compressed liquid shell causes the nucleation of cavitation sites, leading to the radial breakup of the shell and the formation of jets upon expansion. In the current study, a wide variety of granular materials and liquids were explosively dispersed. The maximum terminal jet tip or shell velocity was measured using high-speed videography. Charges were constructed using thin-walled glass bulbs of various diameters and contained a central C-4 charge surrounded by the material to be dispersed. This permitted variation of the ratio of material mass to charge mass ( M/ C) from 4 to 300. Results indicated that material velocity broadly correlates with predictions of the Gurney model. For liquids, the terminal velocity was accurately predicted by the Gurney model. For granular materials, Gurney over-predicted the terminal velocity by 25-60%, depending on the M/ C ratio, with larger M/ C values exhibiting larger deficits. These deficits are explained by energy dissipation during the collapse of voids in the granular material bed. Velocity deficits were insensitive to the degree of jetting and granular material properties. Empirical corrections to the Gurney model are presented with improved agreement with the dry powder experimental velocities.

Impacts of halogen additions on mercury oxidation, in a slipstream selective catalyst reduction (SCR), reactor when burning sub-bituminous coal.

Science.gov (United States)

Cao, Yan; Gao, Zhengyang; Zhu, Jiashun; Wang, Quanhai; Huang, Yaji; Chiu, Chengchung; Parker, Bruce; Chu, Paul; Pant, Wei-Ping

2008-01-01

This paper presents a comparison of impacts of halogen species on the elemental mercury (Hg(0)) oxidation in a real coal-derived flue gas atmosphere. It is reported there is a higher percentage of Hg(0) in the flue gas when burning sub-bituminous coal (herein Powder River Basin (PRB) coal) and lignite, even with the use of selective catalytic reduction (SCR). The higher Hg(0)concentration in the flue gas makes it difficult to use the wet-FGD process for the mercury emission control in coal-fired utility boilers. Investigation of enhanced Hg(0) oxidation by addition of hydrogen halogens (HF, HCl, HBr, and HI) was conducted in a slipstream reactor with and without SCR catalysts when burning PRB coal. Two commercial SCR catalysts were evaluated. SCR catalyst no. 1 showed higher efficiencies of both NO reduction and Hg(0) oxidation than those of SCR catalyst no. 2. NH3 addition seemed to inhibit the Hg(0) oxidation, which indicated competitive processes between NH3 reduction and Hg(0) oxidation on the surface of SCR catalysts. The hydrogen halogens, in the order of impact on Hg(0) oxidation, were HBr, HI, and HCl or HF. Addition of HBr at approximately 3 ppm could achieve 80% Hg(0) oxidation. Addition of HI at approximately 5 ppm could achieve 40% Hg(0) oxidation. In comparison to the empty reactor, 40% Hg(0) oxidation could be achieved when HCl addition was up to 300 ppm. The enhanced Hg(0) oxidation by addition of HBr and HI seemed not to be correlated to the catalytic effects by both evaluated SCR catalysts. The effectiveness of conversion of hydrogen halogens to halogen molecules or interhalogens seemed to be attributed to their impacts on Hg(0) oxidation.

Neocortical layers I and II of the hedgehog (Erinaceus europaeus). I. Intrinsic organization.

Science.gov (United States)

Valverde, F; Facal-Valverde, M V

1986-01-01

The intrinsic organization and interlaminar connections in neocortical layers I and II have been studied in adult hedgehogs (Erinaceus europaeus) using the Golgi method. Layer I contains a dense plexus of horizontal fibers, the terminal dendritic bouquets of pyramidal cells of layer II and of underlying layers, and varieties of intrinsic neurons. Four main types of cells were found in layer I. Small horizontal cells represent most probably persisting foetal horizontal cells described for other mammals. Large horizontal cells, tufted cells, and spinous horizontal cells were also found in this layer. Layer II contains primitive pyramidal cells representing the most outstanding feature of the neocortex of the hedgehog. Most pyramidal cells in layer II have two, three or more apical dendrites, richly covered by spines predominating over the basal dendrites. These cells resemble pyramidal cells found in the piriform cortex, hippocampus and other olfactory areas. It is suggested that the presence of these neurons reflects the retention of a primitive character in neocortical evolution. Cells with intrinsic axons were found among pyramidal cells in layer II. These have smooth dendrites penetrating layer I and local axons forming extremely complex terminal arborizations around the bodies and proximal dendritic portions of pyramidal cells. They most probably effect numerous axo-somatic contacts resembling basket cells. The similarity of some axonal terminals with the chandelier type of axonal arborization is discussed. Other varieties of cells located in deep cortical layers and having ascending axons for layers I and II were also studied. It is concluded that the two first neocortical layers represent a level of important integration in this primitive mammal.

Halogen bonding from a hard and soft acids and bases perspective: investigation by using density functional theory reactivity indices.

Science.gov (United States)

Pinter, Balazs; Nagels, Nick; Herrebout, Wouter A; De Proft, Frank

2013-01-07

Halogen bonds between the trifluoromethyl halides CF(3)Cl, CF(3)Br and CF(3)I, and dimethyl ether, dimethyl sulfide, trimethylamine and trimethyl phosphine were investigated using Pearson's hard and soft acids and bases (HSAB) concept with conceptual DFT reactivity indices, the Ziegler-Rauk-type energy-decomposition analysis, the natural orbital for chemical valence (NOCV) framework and the non-covalent interaction (NCI) index. It is found that the relative importance of electrostatic and orbital (charge transfer) interactions varies as a function of both the donor and acceptor molecules. Hard and soft interactions were distinguished and characterised by atomic charges, electrophilicity and local softness indices. Dual-descriptor plots indicate an orbital σ hole on the halogen similar to the electrostatic σ hole manifested in the molecular electrostatic potential. The predicted high halogen-bond-acceptor affinity of N-heterocyclic carbenes was evidenced in the highest complexation energy for the hitherto unknown CF(3) I·NHC complex. The dominant NOCV orbital represents an electron-density deformation according to a n→σ*-type interaction. The characteristic signal found in the reduced density gradient versus electron-density diagram corresponds to the non-covalent interaction between contact atoms in the NCI plots, which is the manifestation of halogen bonding within the NCI theory. The unexpected C-X bond strengthening observed in several cases was rationalised within the molecular orbital framework. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pyrimidine and halogenated pyrimidines near edge x-ray absorption fine structure spectra at C and N K-edges: experiment and theory

International Nuclear Information System (INIS)

Bolognesi, P.; O'Keeffe, P.; Ovcharenko, Y.; Coreno, M.; Avaldi, L.; Feyer, V.; Plekan, O.; Prince, K. C.; Zhang, W.; Carravetta, V.

2010-01-01

The inner shell excitation of pyrimidine and some halogenated pyrimidines near the C and N K-edges has been investigated experimentally by near edge x-ray absorption fine structure spectroscopy and theoretically by density functional theory calculations. The selected targets, 5-Br-pyrimidine, 2-Br-pyrimidine, 2-Cl-pyrimidine, and 5-Br-2-Cl-pyrimidine, allow the effects of the functionalization of the pyrimidine ring to be studied either as a function of different halogen atoms bound to the same molecular site or as a function of the same halogen atom bound to different molecular sites. The results show that the individual characteristics of the different spectra of the substituted pyrimidines can be rationalized in terms of variations in electronic and geometrical structures of the molecule depending on the localization and the electronegativity of the substituent.

Evidence for a continuous decline in lower stratospheric ozone offsetting ozone layer recovery

Science.gov (United States)

Ball, William T.; Alsing, Justin; Mortlock, Daniel J.; Staehelin, Johannes; Haigh, Joanna D.; Peter, Thomas; Tummon, Fiona; Stübi, Rene; Stenke, Andrea; Anderson, John; Bourassa, Adam; Davis, Sean M.; Degenstein, Doug; Frith, Stacey; Froidevaux, Lucien; Roth, Chris; Sofieva, Viktoria; Wang, Ray; Wild, Jeannette; Yu, Pengfei; Ziemke, Jerald R.; Rozanov, Eugene V.

2018-02-01

Ozone forms in the Earth's atmosphere from the photodissociation of molecular oxygen, primarily in the tropical stratosphere. It is then transported to the extratropics by the Brewer-Dobson circulation (BDC), forming a protective ozone layer around the globe. Human emissions of halogen-containing ozone-depleting substances (hODSs) led to a decline in stratospheric ozone until they were banned by the Montreal Protocol, and since 1998 ozone in the upper stratosphere is rising again, likely the recovery from halogen-induced losses. Total column measurements of ozone between the Earth's surface and the top of the atmosphere indicate that the ozone layer has stopped declining across the globe, but no clear increase has been observed at latitudes between 60° S and 60° N outside the polar regions (60-90°). Here we report evidence from multiple satellite measurements that ozone in the lower stratosphere between 60° S and 60° N has indeed continued to decline since 1998. We find that, even though upper stratospheric ozone is recovering, the continuing downward trend in the lower stratosphere prevails, resulting in a downward trend in stratospheric column ozone between 60° S and 60° N. We find that total column ozone between 60° S and 60° N appears not to have decreased only because of increases in tropospheric column ozone that compensate for the stratospheric decreases. The reasons for the continued reduction of lower stratospheric ozone are not clear; models do not reproduce these trends, and thus the causes now urgently need to be established.

Evidence for a Continuous Decline in Lower Stratospheric Ozone Offsetting Ozone Layer Recovery

Science.gov (United States)

Ball, William T.; Alsing, Justin; Mortlock, Daniel J.; Staehelin, Johannes; Haigh, Joanna D.; Peter, Thomas; Tummon, Fiona; Stuebi, Rene; Stenke, Andrea; Anderson, John;

Degradation of halogenated aliphatic compounds by the ammonia- oxidizing bacterium Nitrosomonas europaea.

Science.gov (United States)

Vannelli, T; Logan, M; Arciero, D M; Hooper, A B

1990-01-01

Suspensions of Nitrosomonas europaea catalyzed the ammonia-stimulated aerobic transformation of the halogenated aliphatic compounds dichloromethane, dibromomethane, trichloromethane (chloroform), bromoethane, 1,2-dibromoethane (ethylene dibromide), 1,1,2-trichloroethane, 1,1,1-trichloroethane, monochloroethylene (vinyl chloride), gem-dichloroethylene, cis- and trans-dichloroethylene, cis-dibromoethylene, trichloroethylene, and 1,2,3-trichloropropane, Tetrachloromethane (carbon tetrachloride), tetrachloroethylene (perchloroethylene), and trans-dibromoethylene were not degraded. PMID:2339874

21 CFR 700.15 - Use of certain halogenated salicylanilides as ingredients in cosmetic products.

Science.gov (United States)

2010-04-01

... ingredients in cosmetic products. 700.15 Section 700.15 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.15 Use of certain halogenated salicylanilides as ingredients in cosmetic products. (a...

Optical terminal requirements for aeronautical multi-hop networks

Science.gov (United States)

Karras, Kimon; Marinos, Dimitris; Kouros, Pavlos

2008-08-01

High speed free space optical data links are currently finding limited use in military aircraft; however the technology is slowly starting to diffuse to civilian applications, where they could be used to provide a high bandwidth connection. However there are several issues that have to be resolved before the technology is ready for deployment. An important part of these are physical layer issues which deal with the ability to transmit and receive the optical signal reliably, as well as mechanical issues which focus on the construction of high performance, small and lightweight terminals for the optical transceiver. The later in conjunction with the cost of such a terminal create a significant limitation on the number of such equipment that any aircraft might carry on board. This paper attempts to evaluate how various such parameters affect the capability of an aircraft to take part in and help form a mesh network. The study was conducted by modeling the aircraft into a custom built SystemC based simulator tool and evaluating the connectivity achieved for varying several parameters, such as the pointing and acquisition time of the terminal and the number of terminals on board.

Coherent current states in mesoscopic four-terminal Josephson junction

International Nuclear Information System (INIS)

Zareyan, M.; Omelyanchouk, A.N.

1999-01-01

A theory is offered for the ballistic 4-terminal Josephson junction. The studied system consist of a mesoscopic two-dimensional normal rectangular layer which is attached on each side to the bulk superconducting banks (terminals). A relation is obtained between the currents through the different terminals, that is valid for arbitrary temperatures and junction sizes. The nonlocal coupling of the supercurrent leads to a new effect, specific for the mesoscopic weak link between two superconducting rings; an applied magnetic flux through one of the rings produces a magnetic flux in the other ring even in the absence of an external flux through the other one. The phase dependent distributions of the local density of Andreev states, of the supercurrents and of the induced order parameter are obtained. The 'interference pattern' for the anomalous average inside the two-dimensional region cam be regulated by the applied magnetic fluxes or the transport currents. For some values of the phase differences between the terminals, the current vortex state and two-dimensional phase slip center appear

Four-terminal organic solar cell modules with increased annual energy yield

NARCIS (Netherlands)

Gehlhaar, R.; Cheyns, D.; Willigenburg, L. van; Hadipour, A.; Gilot, J.; Radbeh, R.; Aernouts, T.

2013-01-01

The authors present experimental results on mechanically stacked organic solar modules and their advantage over standard tandem architectures. A four-terminal configuration of two single junction modules with complementary absorbing active layers uses the more efficient energy conversion of a tandem

Ab initio study of weakly bound halogen complexes: RX⋯PH3.

Science.gov (United States)

Georg, Herbert C; Fileti, Eudes E; Malaspina, Thaciana

2013-01-01

Ab initio calculations were employed to study the role of ipso carbon hybridization in halogenated compounds RX (R=methyl, phenyl, acetyl, H and X=F, Cl, Br and I) and its interaction with a phosphorus atom, as occurs in the halogen bonded complex type RX⋯PH3. The analysis was performed using ab initio MP2, MP4 and CCSD(T) methods. Systematic energy analysis found that the interaction energies are in the range -4.14 to -11.92 kJ mol(-1) (at MP2 level without ZPE correction). Effects of electronic correlation levels were evaluated at MP4 and CCSD(T) levels and a reduction of up to 27% in interaction energy obtained in MP2 was observed. Analysis of the electrostatic maps confirms that the PhCl⋯PH3 and all MeX⋯PH3 complexes are unstable. NBO analysis suggested that the charge transfer between the moieties is bigger when using iodine than bromine and chlorine. The electrical properties of these complexes (dipole and polarizability) were determined and the most important observed aspect was the systematic increase at the dipole polarizability, given by the interaction polarizability. This increase is in the range of 0.7-6.7 u.a. (about 3-7%).

Parent and halogenated polycyclic aromatic hydrocarbons in rice and implications for human health in China

International Nuclear Information System (INIS)

Ding Chao; Ni Honggang; Zeng Hui

2012-01-01

Rice is the staple food for approximate two thirds of the Chinese population. However, human exposure to parent and halogenated polycyclic aromatic hydrocarbons (PAHs) via rice consumption is still not clear for Chinese people so far. The goals of this work are to assess human exposure to PAHs and halogenated PAHs (HPAHs) via rice ingestion and the cancer risk for Chinese population. 16 PAHs and eight HPAHs were determined in rice samples collected from 18 provinces in China. In general terms, the general population in China was exposed to higher levels of PAHs via rice ingestion in comparison to that via cereals for other countries. The cancer risk values induced by exposure to PAHs and HPAHs for male and female on each age group were between the priority risk level (10 −4 ) and the acceptable risk level (10 −6 ). Children faced the highest cancer risk, followed by adolescents and adults. - Highlights: ► Dietary exposure to PAHs via rice ingestion for Chinese population was higher than that via cereals in other countries. ► The cancer risk induced by PAHs and HPAHs intakes via rice consumption were between 10 −6 and 10 −4 . ► Children faced the highest cancer risk, followed by adolescents and adults. ► Given all exposure routes were considered, the real cancer risk for Chinese people would be greater. - Human exposure to parent and halogenated PAHs via rice ingestion and the cancer risk for Chinese population were assessed.

Cold cathode emission studies on topographically modified few layer and single layer MoS2 films

Science.gov (United States)

Gaur, Anand P. S.; Sahoo, Satyaprakash; Mendoza, Frank; Rivera, Adriana M.; Kumar, Mohit; Dash, Saroj P.; Morell, Gerardo; Katiyar, Ram S.

2016-01-01

Nanostructured materials, such as carbon nanotubes, are excellent cold cathode emitters. Here, we report comparative field emission (FE) studies on topographically tailored few layer MoS2 films consisting of ⟨0001⟩ plane perpendicular (⊥) to c-axis (i.e., edge terminated vertically aligned) along with planar few layer and monolayer (1L) MoS2 films. FE measurements exhibited lower turn-on field Eto (defined as required applied electric field to emit current density of 10 μA/cm2) ˜4.5 V/μm and higher current density ˜1 mA/cm2, for edge terminated vertically aligned (ETVA) MoS2 films. However, Eto magnitude for planar few layer and 1L MoS2 films increased further to 5.7 and 11 V/μm, respectively, with one order decrease in emission current density. The observed differences in emission behavior, particularly for ETVA MoS2 is attributed to the high value of geometrical field enhancement factor (β), found to be ˜1064, resulting from the large confinement of localized electric field at edge exposed nanograins. Emission behavior of planar few layers and 1L MoS2 films are explained under a two step emission mechanism. Our studies suggest that with further tailoring the microstructure of ultra thin ETVA MoS2 films would result in elegant FE properties.

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.

Distributions of alkali metals, alkaline earth metals and halogens in cabbage leaves

International Nuclear Information System (INIS)

Tsukada, Hirofumi; Takeda, Akira; Hasegawa, Hidenao

2007-01-01

The distributions of stable elements in plant components provide useful information for understanding the behavior of radionuclides in plants. An entire cabbage plant sample was collected from an experimental field, and the distributions of alkali metals (K, Rb and Cs), alkaline earth metals (Ca, Sr and Ba) and halogens (Cl and I) were determined for cabbage leaves at different positions. The concentration of Cs in outer (older) cabbage leaves was higher than that in inner (younger) leaves, but the distributions of K and Rb concentrations were relatively similar in cabbage leaves, independent of leaf positions. The concentration of Sr in older cabbage leaves was one order of magnitude higher than that in younger leaves. The distributions of Ca, Ba and Sr concentrations in the plant followed a similar pattern. The concentrations of halogens were also very rich in the outer leaves. The percentage distributions of Cs, Sr, Cl and I in the inedible (extreme outer) leaves were 77, 91, 93 and 96% of the total content in the leaf part, respectively. These results show that the inedible plant components are important for understanding the transfer of the radioactive Cs, Sr Cl and I in soil-plant systems. (author)

Tannins and Tannin-Related Derivatives Enhance the (Pseudo-)Halogenating Activity of Lactoperoxidase.

Science.gov (United States)

Gau, Jana; Prévost, Martine; Van Antwerpen, Pierre; Sarosi, Menyhárt-Botond; Rodewald, Steffen; Arnhold, Jürgen; Flemmig, Jörg

2017-05-26

Several hydrolyzable tannins, proanthocyanidins, tannin derivatives, and a tannin-rich plant extract of tormentil rhizome were tested for their potential to regenerate the (pseudo-)halogenating activity, i.e., the oxidation of SCN - to hypothiocyanite - OSCN, of lactoperoxidase (LPO) after hydrogen peroxide-mediated enzyme inactivation. Measurements were performed using 5-thio-2-nitrobenzoic acid in the presence of tannins and related substances in order to determine kinetic parameters and to trace the LPO-mediated - OSCN formation. The results were combined with docking studies and molecular orbital analysis. The - OSCN-regenerating effect of tannin derivatives relates well with their binding properties toward LPO as well as their occupied molecular orbitals. Especially simple compounds like ellagic acid or methyl gallate and the complex plant extract were found as potent enzyme-regenerating compounds. As the (pseudo-)halogenating activity of LPO contributes to the maintenance of oral bacterial homeostasis, the results provide new insights into the antibacterial mode of action of tannins and related compounds. Furthermore, chemical properties of the tested compounds that are important for efficient enzyme-substrate interaction and regeneration of the - OSCN formation by LPO were identified.

Halogenating reaction activity of aromatic organic compounds during disinfection of drinking water

International Nuclear Information System (INIS)

Guo Gaimei; Chen Xiaodong

2009-01-01

The halogenating reactions of five aromatic organic compounds (AOCs) with aqueous chlorine (HOCl/OCl - ) and aqueous bromine (HOBr/OBr - ) were studied with an aim to compare the formation properties of haloacetic acids (HAAs) for the corresponding chlorination or bromination reactions of AOCs, respectively. The experiment results indicated that the HAAs substitution efficiency for the bromination reactions of AOCs was greater than that for the chlorination reactions, and the formation of HAAs had a strong dependence on the chemical structure of AOCs. The chlorination or bromination reaction activities for the AOCs with electron donating functional groups were higher than that for them with electron withdrawing functional groups. The kinetic experiments indicated that the reactions of aqueous bromine with phenol were faster than those of aqueous chlorine with phenol and the halogen consumption exhibited rapid initial and slower consumption stages for the reactions of phenol with aqueous chlorine and bromine, respectively. In addition, the HAAs production for the chlorination reaction of phenol decreased with the increase of pH. These conclusions could provide the valuable information for the effective control of the disinfection by-products during drinking water treatment operation

Layer-selective synthesis of bilayer graphene via chemical vapor deposition

Science.gov (United States)

Yang, Ning; Choi, Kyoungjun; Robertson, John; Park, Hyung Gyu

2017-09-01

A controlled synthesis of high-quality AB-stacked bilayer graphene by chemical vapor deposition demands a detailed understanding of the mechanism and kinetics. By decoupling the growth of the two layers via a growth-and-regrowth scheme, we report the kinetics and termination mechanisms of the bilayer graphene growth on copper. We observe, for the first time, that the secondary layer growth follows Gompertzian kinetics. Our observations affirm the postulate of a time-variant transition from a mass-transport-limited to a reaction-limited regimes and identify the mechanistic disparity between the monolayer growth and the secondary-layer expansion underneath the monolayer cover. It is the continuous carbon supply that drives the expansion of the graphene secondary layer, rather than the initially captured carbon amount, suggesting an essential role of the surface diffusion of reactant adsorbates in the interspace between the top graphene layer and the underneath copper surface. We anticipate that the layer selectivity of the growth relies on the entrance energetics of the adsorbed reactants to the graphene-copper interspace across the primary-layer edge, which could be engineered by tailoring the edge termination state. The temperature-reliant saturation area of the secondary-layer expansion is understood as a result of competitive attachment of carbon and hydrogen adatoms to the secondary-layer graphene edge.

Primary investigation on contamination pattern of legacy and emerging halogenated organic pollutions in freshwater fish from Liaohe River, Northeast China

International Nuclear Information System (INIS)

Ren Guofa; Wang Zhao; Yu Zhiqiang; Wang Yang; Ma Shengtao; Wu Minghong; Sheng Guoying; Fu Jiamo

2013-01-01

Legacy halogenated compounds, including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and emerging organo-halogen pollutants such as Dechlorane Plus (DP), were detected in fish from an old industrial region in Northeast China. PCBs and PBDEs were detected in all of the samples, with concentrations ranging from 38.15 to 170.51 ng/g lipid weight, and 9.40–39.69 ng/g lipid weight, respectively. DP was detected in more than 90% of the samples with concentrations ranging from not detected (ND) to 470 pg g/g lipid weight. Compared with similar data in other areas of the world, PCBs, PBDEs and DP in fish from Liaohe River were at medium or low level. An unusually high percentage of PCB-209 was first reported in the fish samples collected from China. Other halogenated pollutions, such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, octachlorostyrene, chlorinated anisole, chlorinated thioanisole, triclosan-methyl, and other pesticides, have also been identified in the fish samples. - Highlights: ► DP was reported in fish samples from river close to an old industrial base in China. ► The first report on the unusually high fraction of PCB-209 in samples from China. ► GC × GC–TOFMS was used to identify non-targeted halogenated pollutants. - An unusually high percentage of PCB-209 was first reported in the fish samples collected from China, which might indicate that there were distinct sources of pure PCB-209 in the region of Liaohe River.

Use of pyrrole black in zinc-halogen batteries

Energy Technology Data Exchange (ETDEWEB)

Mengoli, G.; Musiani, M.M.; Tomat, R.; Valcher, S.; Pletcher, D.

1985-09-01

The storage of Br/sub 2//Br/sup -/ and I/sub 2//I/sup -/ couples in a conducting polymer matrix, polypyrrole coated on a reticulated vitreous carbon disc, is described and the application of these positive electrodes in zinc-halogen model batteries is discussed. The cell based on the polypyrrole bromine adduct shows the higher open circuit voltage which, however, depends on the state of charge. Such cells self discharge thus limiting their usefulness. In the case of the iodine cell the self discharge is due to loss of iodine from the polymer to the bulk solution, but with the bromine cell the cause is oxidative bromination and depolymerization of the polypyrrole. 22 references, 6 figures, 2 tables.

Successful Endoscopic Submucosal Dissection of a Large Terminal Ileal Lipoma

Directory of Open Access Journals (Sweden)

Hisatsugu Noda

2016-10-01

Full Text Available A 78-year-old woman who had recurrent right lower abdominal pain for about 1 year underwent computed tomography (CT because of a follow-up observation 1 year after right breast cancer surgery. CT revealed a tumor in the colon. The patient was referred to our hospital for detailed examinations. An abdominal CT showed a low-density tumor of approximately 30 mm in the ascending colon, and the CT density inside the tumor was same as that of fatty tissues. A subsequent colonoscopy showed a submucosal tumor (SMT in the proximal ascending colon developing from the terminal ileum. A colonoscopic ultrasonography revealed that the SMT was a high-echoic mass mainly localized in the submucosal layer. Based on the findings from CT, colonoscopy, and colonoscopic ultrasonography, the SMT was diagnosed as a pedunculated lipoma originating from the terminal ileum and treated with endoscopic submucosal dissection (ESD because of recurrent abdominal pain. The 40-mm tumor was resected en bloc without complications. ESD may be more appropriate than polypectomy and surgery for removal of small intestinal tumors, because ESD allows direct visualization of the cutting line and exactly dissects the submucosal layers without damaging the muscular layers. ESD is a potentially useful treatment to remove intestinal lipomas.

Generation and alteration of the defects induced by particle irradiation and electromagnetic radiation in alkali halogen compounds

International Nuclear Information System (INIS)

Nistor, L.C.

1979-01-01

Interactions between electron beams, CO 2 - laser radiation and alkali halogen compound have led to interesting results: 1. The development of two types of F-centre respectively in normal lattice or near the dislocations. 2. The beginning of metal colloids development process at low temperature when a thermal treatment is applied. 3. An experimental confirmation of the Pooley-Hersh model for crystal defects has been brought up. 4. The surface penetration is an explosive process. 5. Surface polygonizations were also investigated. A model has been proposed to describe the destructive channels development within alkali halogen crystals with molecular anions impurities of less than 10 ppm. KCl monocrystals of advanced purity level was prepared for building up passive optical components of strong CO 2 lasers. (author)

Electronic and magnetic properties of the Co{sub 2}MnAl/Au interface: Relevance of the Heusler alloy termination

Energy Technology Data Exchange (ETDEWEB)

Makinistian, L., E-mail: lmakinistian@santafe-conicet.gov.ar [Instituto de Física del Litoral (CONICET-UNL), Güemes 3450, 3000 Santa Fe (Argentina); Facultad de Ingeniería, Universidad Nacional de Entre Ríos, 3101 Oro Verde (Argentina); Albanesi, E.A. [Instituto de Física del Litoral (CONICET-UNL), Güemes 3450, 3000 Santa Fe (Argentina); Facultad de Ingeniería, Universidad Nacional de Entre Ríos, 3101 Oro Verde (Argentina)

2015-07-01

We present ab initio calculations of electronic and magnetic properties of the ferromagnetic metal/normal metal (F/N) interface of the Heusler alloy Co{sub 2}MnAl and gold. Two structural models are implemented: one with the ferromagnet slab terminated in a pure cobalt plane (“Co{sub 2}-t”), and the other with it terminated with a plane of MnAl (“MnAl-t”). The relaxed optimum distance between the slabs is determined for the two models before densities of states, magnetic moments, and the electric potential are resolved and analyzed layer by layer through the interface. Complementary, calculations for the free surfaces of gold and the Heusler alloy (for both models, Co{sub 2}-t and MnAl-t) are performed for a better interpretation of the physics of the interface. We predict important differences between the two models, suggesting that both terminations are to be expected to display sensibly different spin injection performances. - Highlights: • Ab initio electronic and magnetic properties of the interface Co{sub 2}MnAl/Au. • Two terminations were studied: Co{sub 2} and MnAl terminated. • The termination of the Heusler alloy sensibly determines the interface properties. • The Co{sub 2} terminated interface displays a higher spin polarization.

The effect of halogen light stimulation on duration of ultrasound parameters of biophysical profile: a randomized clinical trial.

Science.gov (United States)

Hanafi, Mohammad Ghasem; Sahraeizadeh, Aliakbar

2018-02-22

The objective is to assess if fetal halogen light stimulation can reduce the time needed to obtain a normal biophysical profile (BPP). Patients scheduled for a BPP and who satisfied the inclusion criteria were prospectively randomized to halogen light stimulation and no stimulation groups. The study group was exposed to handheld halogen light for 10 s whenever fetal breathing, movement, or tone was absent through the first 5 min of BPP. The time required to achieve complete BPP score was recorded. In patients with complete BPP score who had delivery within 1 week after the test, perinatal morbidity was examined. A total of 598 patients were randomized (light = 302, no light = 296). There was no difference between the two groups in terms of gestational age, maternal age, body mass index, and indication for BPP except for preterm labor (light: 9%, no light: 4%, p = 0.03). Among the patients who had a normal BPP score (n = 507), the mean (light: 7.1 ± 6 min, no light: 12.3 ± 8 min, p BPP score was significantly less in the light stimulation group than the no stimulation group. Perinatal outcomes were not different between groups who had delivery during the first week after BPP. Fetal halogen light stimulation can be utilized to reduce the time needed to complete a BPP. However, further studies should be conducted in order to determine the effect of this method on decreasing non-reassuring test results. The study was submitted to the Registry of Clinical Trials on 04/20/2017 (IRCT2017041633470N1). After IRCT registration on 06/07/2017, we recruited patients from 06/08/2017 till 10/15/2017.

Development and application of a sampling method for the determination of reactive halogen species in volcanic gas emissions

Science.gov (United States)

Rüdiger, Julian; Bobrowski, Nicole; Liotta, Marcello; Hoffmann, Thorsten

2017-04-01

Volcanoes are a potential large source of several reactive atmospheric trace gases including sulfur and halogen containing species. Besides the importance for atmospheric chemistry, the detailed knowledge of halogen chemistry in volcanic plumes can help to get insights into subsurface processes. In this study a gas diffusion denuder sampling method, using a 1,3,5-trimethoxybenzene (1,3,5-TMB) coating for the derivatization of reactive halogen species (RHS), was characterized by dilution chamber experiments. The coating proved to be suitable to collect selectively gaseous bromine species with oxidation states (OS) of +1 or 0 (such as Br2, BrCl, BrO(H) and BrONO2), while being ignorant to HBr (OS -1). The reaction of 1,3,5-TMB with reactive bromine species gives 1-bromo-2,4,6-trimethoxybenzene (1-bromo-2,4,6-TMB) - other halogens give corresponding products. Solvent elution of the derivatized analytes and subsequent analysis with gas chromatography mass spectrometry gives detection limits of 10 ng or less for Br2, Cl2, and I2. In 2015 the method was applied on volcanic gas plumes at Mt. Etna (Italy) giving reactive bromine mixing ratios from 0.8 ppbv to 7.0 ppbv. Total bromine mixing ratios of 4.7 ppbv to 27.5 ppbv were obtained by simultaneous alkaline trap sampling (by a Raschig-tube) followed by analysis with ion chromatography and inductively coupled plasma mass spectrometry. This leads to the first results of in-situ measured reactive bromine to total bromine ratios, spanning a range between 12±1 % and 36±2 %. Our finding is in an agreement with previous model studies, which imply values < 44 % for plume ages < 1 minute, which is consistent with the assumed plume age at the sampling sites.

Structures and anti-inflammatory properties of 4-halogenated -mofebutazones

Science.gov (United States)

Reichelt, Hendrik; Paradies, Henrich H.

2018-02-01

The crystal structures of the 4-halogenated (hal: F, Cl, Br)-4-butyl-1-phenyl-1,3-pyrolidine-dione (mofebutazone) are determined, and compared with their solution structures. The racemic 4-halogenated mofebutazone approximants crystallize in a monoclinic space group with four molecules in the unit cell. The 4-hal-mofebutazone molecules reveal strong hydrogen bonding between the hydrogen atom located at the N-2 nitrogen atom and a carbonyl oxygen atom of an adjacent 4-hal-mofebutazone molecule. The hydrogen bond angle for 4-Br-mifebutazone N (2)sbnd H (1)⋯O (1) is 173(3) °, so that the hydrogen bond is essentially linear indicating an infinite chain hydrogen bond network. The 3d and 2d structures are stabilized by π-π and σ-π interactions, short intermolecular distances, and apolar forces between adjacently stacked phenyl rings. Small-angle-X-ray scattering (SAXS) experiments and osmometric measurements reveal the presence of dimers for the 4-hal-mofebutazone molecules. Molecular simulations indicate similar solution structure factors for the 4-hal-mofebutazones solutions, S(Q), and in the solid state. There is a strong indication that the [1,1,0], [1,0,0], and [1,0,0] periodicities of the 4-Brsbnd , 4-Clsbnd and 4-F-mofebutazone in the crystalline solid state were also present in the solution phase. The biochemical and cellular activities of the different 4-hal-mofebutazones were monitored by the magnitude of their inhibition of the PGE2 biosynthesis through the cyclo-oxygenase (COX-1) in macrophages, and on the inhibition of LTD4 (5-lipoxygenase) in polymorphonuclear leukocytes.

Modeling and observational constraints on the sulfur cycle in the marine troposphere: a focus on reactive halogens and multiphase chemistry

Science.gov (United States)

Chen, Q.; Breider, T.; Schmidt, J.; Sherwen, T.; Evans, M. J.; Xie, Z.; Quinn, P.; Bates, T. S.; Alexander, B.

2017-12-01

The radiative forcing from marine boundary layer clouds is still highly uncertain, which partly stems from our poor understanding of cloud condensation nuclei (CCN) formation. The oxidation of dimethyl sulfide (DMS) and subsequent chemical evolution of its products (e.g. DMSO) are key processes in CCN formation, but are generally very simplified in large-scale models. Recent research has pointed out the importance of reactive halogens (e.g. BrO and Cl) and multiphase chemistry in the tropospheric sulfur cycle. In this study, we implement a series of sulfur oxidation mechanisms into the GEOS-Chem global chemical transport model, involving both gas-phase and multiphase oxidation of DMS, DMSO, MSIA and MSA, to improve our understanding of the sulfur cycle in the marine troposphere. DMS observations from six locations around the globe and MSA/nssSO42- ratio observations from two ship cruises covering a wide range of latitudes and longitudes are used to assess the model. Preliminary results reveal the important role of BrO for DMS oxidation at high latitudes (up to 50% over Southern Ocean). Oxidation of DMS by Cl radicals is small in the model (within 10% in the marine troposphere), probably due to an underrepresentation of Cl sources. Multiphase chemistry (e.g. oxidation by OH and O3 in cloud droplets) is not important for DMS oxidation but is critical for DMSO oxidation and MSA production and removal. In our model, about half of the DMSO is oxidized in clouds, leading to the formation of MSIA, which is further oxidized to form MSA. Overall, with the addition of reactive halogens and multiphase chemistry, the model is able to better reproduce observations of seasonal variations of DMS and MSA/nssSO42- ratios.

The Effects of Water Spray Cooling in Conjunction with Halogenated Extinguishants on Hydrogen Fluoride Generation and Decay

National Research Council Canada - National Science Library

Burch, Ian

2007-01-01

The halogenated extinguishants Halon 1301, HFC-227ea (FM200) and NAF-S-III used within Royal Australian Navy vessels for total flooding fire suppression applications have hydrogen fluoride (HF) toxicity concerns...

Chain reaction on de-halogenation of 1,2-dibromotetrafluoroethane and 1,1,2-trichlorotrifluoroethane induced by irradiation in alcohols

International Nuclear Information System (INIS)

Nakagawa, Seiko

2015-01-01

Methanol and 2-propanol solutions of 1,2-dibromotetrafluoroethane and 1,1,2-trichlorotrifluoroethane were irradiated with γ-rays after perfect de-oxygenation. The product, formed by the substitution of one of the bromine or chlorine atoms with a hydrogen atom, was observed by radiation-induced degradation and the product was also de-halogenated. The G-value of de-halogenation was more than a thousand times higher than G(e solv − ) and increased with the decreasing dose rate, meaning that a chain reaction is involved in the process. The efficiency of the degradation in 2-propanol was several times higher than that in methanol. It is concluded that the charge transfer from an alcohol radical will be the trigger of the chain reaction the same as in the degradation of hexachloroethane in alcohol solutions (Sawai et al., 1978). - Highlights: • Halone2402 and Furon113 were de-halogenated by radiation-induced chain reaction in pure alcohol. • The efficiency of the degradation in 2-propanol was several times higher than that in methanol. • The charge transfer from an alcohol radical will be the trigger of the chain reaction

QSPR models of n-octanol/water partition coefficients and aqueous solubility of halogenated methyl-phenyl ethers by DFT method.

Science.gov (United States)

Zeng, Xiao-Lan; Wang, Hong-Jun; Wang, Yan

2012-02-01

The possible molecular geometries of 134 halogenated methyl-phenyl ethers were optimized at B3LYP/6-31G(*) level with Gaussian 98 program. The calculated structural parameters were taken as theoretical descriptors to establish two new novel QSPR models for predicting aqueous solubility (-lgS(w,l)) and n-octanol/water partition coefficient (lgK(ow)) of halogenated methyl-phenyl ethers. The two models achieved in this work both contain three variables: energy of the lowest unoccupied molecular orbital (E(LUMO)), most positive atomic partial charge in molecule (q(+)), and quadrupole moment (Q(yy) or Q(zz)), of which R values are 0.992 and 0.970 respectively, their standard errors of estimate in modeling (SD) are 0.132 and 0.178, respectively. The results of leave-one-out (LOO) cross-validation for training set and validation with external test sets both show that the models obtained exhibited optimum stability and good predictive power. We suggests that two QSPR models derived here can be used to predict S(w,l) and K(ow) accurately for non-tested halogenated methyl-phenyl ethers congeners. Copyright © 2011 Elsevier Ltd. All rights reserved.

The effect of sulphur-terminated GaAs substrates on the MOVPE growth of CuGaS2 thin films

International Nuclear Information System (INIS)

Berndt, P.R.; Botha, J.R.; Branch, M.S.; Leitch, A.W.R.; Kirmse, H.; Neumann, W.; Weber, J.

2007-01-01

In this study, various CuGaS 2 layers were grown on GaAs (001) substrates using metalorganic vapour phase epitaxy, for the purpose of studying the effect of sulphur-termination of the substrate on layer quality. The resultant films were investigated using X-ray diffractometry, and transmission electron microscopy, with high-resolution transmission electron microscopy providing additional insights into crystallite growth on the control substrates. This paper will demonstrate that sulphur-termination limits substrate degradation. In the absence of sulphur-termination, atypical three-dimensional MOVPE growth is observed, with epitaxial crystallites varying in size from 10 nm to 200 nm. Substrate degradation inhibits lateral growth at the interface resulting in amorphous regions, cavities, and epitaxial crystallites demonstrating overgrowth into mushroom-like structures

Primary investigation on contamination pattern of legacy and emerging halogenated organic pollutions in freshwater fish from Liaohe River, Northeast China

Energy Technology Data Exchange (ETDEWEB)

Ren Guofa, E-mail: rgf2008@shu.edu.cn [Institute of Environmental Pollution and Health, School of Environment and Chemical Engineering, Shanghai University, 99 Shangda Road, Baoshan Disrict, Shanghai 200072 (China); Zhao, Wang [Institute of Environmental Pollution and Health, School of Environment and Chemical Engineering, Shanghai University, 99 Shangda Road, Baoshan Disrict, Shanghai 200072 (China); Zhiqiang, Yu [State Key Laboratory of Organic Geochemistry, Guangzhou Key Laboratory of Environment Protection and Resource Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Yang, Wang [Institute of Environmental Pollution and Health, School of Environment and Chemical Engineering, Shanghai University, 99 Shangda Road, Baoshan Disrict, Shanghai 200072 (China); Shengtao, Ma [State Key Laboratory of Organic Geochemistry, Guangzhou Key Laboratory of Environment Protection and Resource Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Minghong, Wu [Institute of Environmental Pollution and Health, School of Environment and Chemical Engineering, Shanghai University, 99 Shangda Road, Baoshan Disrict, Shanghai 200072 (China); Guoying, Sheng [State Key Laboratory of Organic Geochemistry, Guangzhou Key Laboratory of Environment Protection and Resource Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Jiamo, Fu [Institute of Environmental Pollution and Health, School of Environment and Chemical Engineering, Shanghai University, 99 Shangda Road, Baoshan Disrict, Shanghai 200072 (China); State Key Laboratory of Organic Geochemistry, Guangzhou Key Laboratory of Environment Protection and Resource Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)

2013-01-15

Legacy halogenated compounds, including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and emerging organo-halogen pollutants such as Dechlorane Plus (DP), were detected in fish from an old industrial region in Northeast China. PCBs and PBDEs were detected in all of the samples, with concentrations ranging from 38.15 to 170.51 ng/g lipid weight, and 9.40-39.69 ng/g lipid weight, respectively. DP was detected in more than 90% of the samples with concentrations ranging from not detected (ND) to 470 pg g/g lipid weight. Compared with similar data in other areas of the world, PCBs, PBDEs and DP in fish from Liaohe River were at medium or low level. An unusually high percentage of PCB-209 was first reported in the fish samples collected from China. Other halogenated pollutions, such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, octachlorostyrene, chlorinated anisole, chlorinated thioanisole, triclosan-methyl, and other pesticides, have also been identified in the fish samples. - Highlights: Black-Right-Pointing-Pointer DP was reported in fish samples from river close to an old industrial base in China. Black-Right-Pointing-Pointer The first report on the unusually high fraction of PCB-209 in samples from China. Black-Right-Pointing-Pointer GC Multiplication-Sign GC-TOFMS was used to identify non-targeted halogenated pollutants. - An unusually high percentage of PCB-209 was first reported in the fish samples collected from China, which might indicate that there were distinct sources of pure PCB-209 in the region of Liaohe River.

Converting a conventional wired-halogen illuminated indirect ophthalmoscope to a wireless-light emitting diode illuminated indirect ophthalmoscope in less than 1000/- rupees

Directory of Open Access Journals (Sweden)

Mihir Kothari

2015-01-01

Full Text Available Aim: To report the "do it yourself" method of converting an existing wired-halogen indirect ophthalmoscope (IO to a wireless-light emitting diode (LED IO and report the preferences of the patients and the ophthalmologists. Subjects and Methods: In this prospective observational study, a conventional IO was converted to wireless-LED IO using easily available, affordable electrical components. Conventional and the converted IO were then used to perform photo-stress test and take the feedback of subjects and the ophthalmologists regarding its handling and illumination characteristics. Results: The cost of conversion to wireless-LED was 815/- rupees. Twenty-nine subjects, mean age 34.3 ΁ 10 years with normal eyes were recruited in the study. Between the two illumination systems, there was no statistical difference in the magnitude of the visual acuity loss and the time to recovery of acuity and the bleached vision on photo-stress test, although the visual recovery was clinically faster with LED illumination. The heat sensation was more with halogen illumination than the LED (P = 0.009. The ophthalmologists rated wireless-LED IO higher than wired-halogen IO on the handling, examination comfort, patient′s visual comfort and quality of the image. Twenty-two (81% ophthalmologists wanted to change over to wireless-LED IO. Conclusions: Converting to wireless-LED IO is easy, cost-effective and preferred over a wired-halogen indirect ophthalmoscope.

Converting a conventional wired-halogen illuminated indirect ophthalmoscope to a wireless-light emitting diode illuminated indirect ophthalmoscope in less than 1000/- rupees.

Science.gov (United States)

Kothari, Mihir; Kothari, Kedar; Kadam, Sanjay; Mota, Poonam; Chipade, Snehal

2015-01-01

To report the "do it yourself" method of converting an existing wired-halogen indirect ophthalmoscope (IO) to a wireless-light emitting diode (LED) IO and report the preferences of the patients and the ophthalmologists. In this prospective observational study, a conventional IO was converted to wireless-LED IO using easily available, affordable electrical components. Conventional and the converted IO were then used to perform photo-stress test and take the feedback of subjects and the ophthalmologists regarding its handling and illumination characteristics. The cost of conversion to wireless-LED was 815/- rupees. Twenty-nine subjects, mean age 34.3 [formula in text] 10 years with normal eyes were recruited in the study. Between the two illumination systems, there was no statistical difference in the magnitude of the visual acuity loss and the time to recovery of acuity and the bleached vision on photo-stress test, although the visual recovery was clinically faster with LED illumination. The heat sensation was more with halogen illumination than the LED (P = 0.009). The ophthalmologists rated wireless-LED IO higher than wired-halogen IO on the handling, examination comfort, patient's visual comfort and quality of the image. Twenty-two (81%) ophthalmologists wanted to change over to wireless-LED IO. Converting to wireless-LED IO is easy, cost-effective and preferred over a wired-halogen indirect ophthalmoscope.

Effects of halogens on interactions between a reduced TiO{sub 2} (110) surface and noble metal atoms: A DFT study

Energy Technology Data Exchange (ETDEWEB)

Tada, Kohei, E-mail: k-tada@aist.go.jp [Department of Chemistry, Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka, 560-0043 (Japan); Research Institute of Electrochemical Energy, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31, Midorigaoka, Ikeda, Osaka, 563-8577 (Japan); Koga, Hiroaki [Element Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, 1-30 Goryo Ohara, Nishikyo, Kyoto, 615-8245 (Japan); Hayashi, Akihide; Kondo, Yudai; Kawakami, Takashi; Yamanaka, Shusuke [Department of Chemistry, Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka, 560-0043 (Japan); Okumura, Mitsutaka [Department of Chemistry, Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka, 560-0043 (Japan); Element Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, 1-30 Goryo Ohara, Nishikyo, Kyoto, 615-8245 (Japan)

2017-07-31

Highlights: • We investigated the halogen effect on the interactions of noble metals with TiO{sub 2}. • Halogen atoms inhibit electron transfer from TiO{sub 2} to noble metals. • Iodine stabilizes the adsorption of noble metals especially for Ag and Cu. • Electron transfer from the TiO{sub 2} is effective in anchoring Au and Pt atoms. • Covalent interaction with the support is effective in anchoring Ag and Cu atoms. - Abstract: Using DFT calculation, we investigate the effects of halogens on the interactions between rutile TiO{sub 2} (110) and noble metal atoms (Au, Ag, Cu, Pt, and Pd). Fluorine, chlorine, and bromine atoms occupy the oxygen defect sites of TiO{sub 2}, decreasing the stability of noble metal atoms on the surface. This decrease occurs because the halogens inhibit electron transfer from TiO{sub 2} to the noble metal atoms; the electron transfer from reduced TiO{sub 2} to the noble metal atom stabilizes the noble metal atom adsorption. In contrast, iodine strengthens the interactions between TiO{sub 2} and some noble metal atoms, namely Ag and Cu. This stabilization occurs because of the covalent interaction between iodine-doped TiO{sub 2} and the noble metal atom. Therefore, the stabilization is explained well by chemical hardness. This result suggests that iodine-doping of a TiO{sub 2} surface would be an effective method for the preparation of highly stabilized noble metal clusters.

Halogen bonded complexes between volatile anaeshetics (chloroform, halothane, enflurane, isoflurane) and formaldehyde: a theoretical study

Czech Academy of Sciences Publication Activity Database

Zierkiewicz, W.; Wieczorek, R.; Hobza, Pavel; Michalska, D.

2011-01-01

Roč. 13, č. 11 (2011), s. 5105-5113 ISSN 1463-9076 R&D Projects: GA MŠk LC512 Institutional research plan: CEZ:AV0Z40550506 Keywords : halogen bond * anaesthetics * ab initio calculation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.573, year: 2011

On the growth of native oxides on hydrogen-terminated silicon surfaces in dark and under illumination with light

NARCIS (Netherlands)

Kovalgin, Alexeij Y.; Zinine, A.; Bankras, R.G.; Wormeester, Herbert; Poelsema, Bene; Schmitz, Jurriaan

2006-01-01

After a cleaning procedure, a silicon surface can be terminated by Si-OH groups which results in a high chemical activity. As it is accepted, after removing the wet-chemically grown oxide layer using an HF solution, the surface becomes terminated with Si-H groups. This results in a chemically stable

Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT): Overview of a wintertime air chemistry field study in the front range urban corridor of Colorado

Science.gov (United States)

Brown, Steven S.; Thornton, Joel A.; Keene, William C.; Pszenny, Alexander A. P.; Sive, Barkley C.; Dubé, William P.; Wagner, Nicholas L.; Young, Cora J.; Riedel, Theran P.; Roberts, James M.; VandenBoer, Trevor C.; Bahreini, Roya; Öztürk, Fatma; Middlebrook, Ann M.; Kim, Saewung; Hübler, Gerhard; Wolfe, Daniel E.

2013-07-01

The Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT) field experiment took place during late winter, 2011, at a site 33 km north of Denver, Colorado. The study included fixed-height measurements of aerosols, soluble trace gases, and volatile organic compounds near surface level, as well as vertically resolved measurements of nitrogen oxides, aerosol composition, soluble gas-phase acids, and halogen species from 3 to 270 m above ground level. There were 1928 individual profiles during the three-week campaign to characterize trace gas and aerosol distributions in the lower levels of the boundary layer. Nitrate and ammonium dominated the ionic composition of aerosols and originated primarily from local or regional sources. Sulfate and organic matter were also significant and were associated primarily with longer-range transport to the region. Aerosol chloride was associated primarily with supermicron size fractions and was always present in excess of gas-phase chlorine compounds. The nighttime radical reservoirs, nitryl chloride, ClNO2, and nitrous acid, HONO, were both consistently present in nighttime urban air. Nitryl chloride was especially pronounced in plumes from large point sources sampled aloft at night. Nitrous acid was typically most concentrated near the ground surface and was the dominant contributor (80%) to diurnally averaged primary OH radical production in near-surface air. Large observed mixing ratios of light alkanes, both in near-surface air and aloft, were attributable to local emissions from oil and gas activities.

Synthesis and improved photochromic properties of pyrazolones in the solid state by incorporation of halogen

Science.gov (United States)

Guo, Jixi; Yuan, Hui; Jia, Dianzeng; Guo, Mingxi; Li, Yinhua

2017-01-01

Four novel photochromic pyrazolones have been prepared by introducing halogen atoms as substituents on the benzene ring. All as-synthesized compounds exhibited excellent reversible photochromic performances in the solid state. Upon UV light irradiation, the as-synthesized compounds can change their structures from E-form to K-form with yellow coloration. Further processed by heating, they rapidly reverted to their initial states at 120 °С. Their photo-response and thermal bleaching kinetics were detailed investigated by UV absorption spectra. The results showed that the time constants were higher than that of our previously reported compounds at least one order of magnitude and the rate constants of the as-synthesized compounds were significantly influenced by the size and electronegativity of different halogen atoms. The fluorescence emission were modulated in a high degree via photoisomerization of pyrazolones, which might be due to the efficient energy transfer from E-form to K-form isomers for their partly overlaps between their E-form absorption spectra and K-form fluorescence spectra.

GC-MS Study of Mono- and Bishaloethylphosphonates Related to Schedule 2.B.04 of the Chemical Weapons Convention: The Discovery of a New Intramolecular Halogen Transfer

Science.gov (United States)

Picazas-Márquez, Nerea; Sierra, María; Nova, Clara; Moreno, Juan Manuel; Aboitiz, Nuria; de Rivas, Gema; Sierra, Miguel A.; Martínez-Álvarez, Roberto; Gómez-Caballero, Esther

2016-09-01

A new class of compounds, mono- and bis-haloethylphosphonates (HAPs and bisHAPs, respectively), listed in Schedule 2.B.04 of the Chemical Weapons Convention (CWC), has been synthesized and studied by GC-MS with two aims. First, to improve the identification of this type of chemicals by the Organization for the Prohibition of Chemical Weapons, (OPCW). Second, to study the synergistic effect of halogen and silicon atoms in molecules undergoing mass spectrometry. Fragmentation patterns of trimethylsilyl derivatives of HAPs were found to depend on the nature of the halogen atom; this was in agreement with DFT-calculations. The data suggest that a novel intramolecular halogen transfer takes place during the fragmentation process.

Verification of the light intensity from halogens curing lamps in comparison with the manufacturer's specifications

International Nuclear Information System (INIS)

Morales Ramirez, Elvis

2011-01-01

The light intensity emitted from halogens curing lamps is measured to determine if photoactivation units utilized in the Caja Costarricense de Seguro Social are complied with the manufacturer's specifications of the lamp and the resin. The light intensity mW/cm 2 from halogens curing lamps operated by odontologist of the Caja Costarricense de Seguro Social is compared with the manufacturer's specifications of the lamp. The light intensity is compared with the manufacturer's specifications of the resin. The results obtained are analyzed to specify that lamp or lamps have presented light intensities lower to indication of the manufacturer. A list of recommendations is performed for each Servicio de Odontologia of the Caja Costarricense de Seguro Social of the Region Central Sur of the results reported [es

Electron-detachment cross sections of halogen negative-ion projectiles for inertial confinement fusion

Science.gov (United States)

Sant'Anna, M. M.; Zappa, F.; Santos, A. C. F.; de Barros, A. L. F.; Wolff, W.; Coelho, L. F. S.; de Castro Faria, N. V.

2004-07-01

Negative-ion beams have recently been suggested as sources of high-energy heavy atoms to be used as drivers for inertial confinement fusion (ICF). Owing to their electron affinities limited to a few eV, anions can be efficiently photo-detached in the vicinity of the fusion chamber, with the resulting high-velocity neutral projectiles following ballistic trajectories towards the hydrogen pellet target. Electron-detachment cross sections are needed as parameters to estimate the beam attenuation in the path from the ion source to the hydrogen pellet. Halogen anions are possible projectile choices. In this paper we present experimental data for total electron-detachment cross sections for F-, Cl-, Br- and I- ions incident on N2, in the 0.94-74 keV u-1 energy range. Our measurements can benchmark theory on anion electron detachment at intermediate to high velocities. Comparison between different projectiles shows very similar collision velocity dependencies. A simple geometrical scaling is presented, providing an estimate for electron-detachment cross sections at the MeV u-1 energy range. The presented scaling indicates that the vacuum requirements due to the use of halogen anions for ICF are less critical than previously suggested.

Electron-detachment cross sections of halogen negative-ion projectiles for inertial confinement fusion

International Nuclear Information System (INIS)

Sant'Anna, M M; Zappa, F; Santos, A C F; Barros, A L F de; Wolff, W; Coelho, L F S; Faria, N V de Castro

2004-01-01

Negative-ion beams have recently been suggested as sources of high-energy heavy atoms to be used as drivers for inertial confinement fusion (ICF). Owing to their electron affinities limited to a few eV, anions can be efficiently photo-detached in the vicinity of the fusion chamber, with the resulting high-velocity neutral projectiles following ballistic trajectories towards the hydrogen pellet target. Electron-detachment cross sections are needed as parameters to estimate the beam attenuation in the path from the ion source to the hydrogen pellet. Halogen anions are possible projectile choices. In this paper we present experimental data for total electron-detachment cross sections for F - , Cl - , Br - and I - ions incident on N 2 , in the 0.94-74 keV u -1 energy range. Our measurements can benchmark theory on anion electron detachment at intermediate to high velocities. Comparison between different projectiles shows very similar collision velocity dependencies. A simple geometrical scaling is presented, providing an estimate for electron-detachment cross sections at the MeV u -1 energy range. The presented scaling indicates that the vacuum requirements due to the use of halogen anions for ICF are less critical than previously suggested

Reactive and Organic Halogen Species in Three Different European Coastal Environments

Science.gov (United States)

Platt, U.; Peters, C.; Pechtl, S.

2005-12-01

Within this contribution results of three field campaigns using active longpath DOAS (Differential Optical Absorption Spectroscopy) for the study of reactive halogen species (RHS) BrO, IO, OIO and I2 are presented. Two recent field campaigns took place in Spring 2002 in Dagebuell at the German North Sea Coast and 2003 in Lilia at the French Atlantic Coast of Brittany. Both sites represent coastal environments, characterized by extended intertidal zones and a moderately polluted atmosphere, with NO2 levels of up to 8 ppb. However, the sites show strong differences in their respective bioactivity. A great variety of macroalgae appeared over extended areas in Brittany, whereas algae were localized in small and rare spots at the German North Sea Coast. During these field campaigns volatile halogenated organic compounds (VHOCs) were determined by GC/ECD-ICPMS in air and water. Due to the spatial distribution of macroalgae at the German North Sea Coast clear evidence was for a connection between elevated levels of VHOCs and the appearance of macroalgae. Extraordinarily high concentrations of several VHOCs, specially CH3I and CH3Br of up to 1830 pptv and 875 pptv, respectively, were observed at the coast of Brittany, demonstrating the outstanding level of bioactivity there. CH2I2, an important source species for reactive iodine in the atmosphere due its short photolytic lifetime of only a few minutes, could be detected of up to 20 pptv. The IO mixing ratio reached up to 7.7±0.5 ppt (pmol/mol) during the day, in reasonable agreement with model studies designed to represent the meteorological and chemical conditions in Brittany. Since macroalgae under oxidative stress are suggested to be a further source for I2 in the marine boundary layer, spectra in the 500-600 nm range were re-analyzed taken during the 1998 PARFORCE campaign in Mace Head, Ireland, which had not previously been analyzed for I2. Molecular iodine could be clearly identified above the detection limit (~20

Reactive and organic halogen species in three different European coastal environments

Directory of Open Access Journals (Sweden)

C. Peters

2005-01-01

Full Text Available We present results of three field campaigns using active longpath DOAS (Differential Optical Absorption Spectroscopy for the study of reactive halogen species (RHS BrO, IO, OIO and I2. Two recent field campaigns took place in Spring 2002 in Dagebüll at the German North Sea Coast and in Spring 2003 in Lilia at the French Atlantic Coast of Brittany. In addition, data from a campaign in Mace Head, Ireland in 1998 was partly re-evaluated. During the recent field campaigns volatile halogenated organic compounds (VHOCs were determined by a capillary gas chromatograph coupled with an electron capture detector and an inductively coupled plasma mass spectrometer (GC/ECD-ICPMS in air and water. Due to the inhomogeneous distribution of macroalgae at the German North Sea Coast we found a clear connection between elevated levels of VHOCs and the appearance of macroalgae. Extraordinarily high concentrations of several VHOCs, especially CH3I and CH3Br of up to 1830 pptv and 875 pptv, respectively, were observed at the coast of Brittany, demonstrating the outstanding level of bioactivity there. We found CH2I2 at levels of up to 20 pptv, and a clear anti-correlation with the appearance of IO. The IO mixing ratio reached up to 7.7±0.5 ppt(pmol/mol during the day, in reasonable agreement with model studies designed to represent the meteorological and chemical conditions in Brittany. For the two recent campaigns the DOAS spectra were evaluated for BrO, OIO and I2, but none of these species could be clearly identified (average detection limits around 2 ppt, 3 ppt, 20 ppt, resp., significantly higher in individual cases. Only in the Mace Head spectra evidence was found for the presence of OIO. Since macroalgae under oxidative stress are suggested to be a further source for I2 in the marine boundary layer, we re-analyzed spectra in the 500–600 nm range taken during the 1998 PARFORCE campaign in Mace Head, Ireland, which had not previously been analyzed for I2. We

Halogenation dictates the architecture of amyloid peptide nanostructures† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7nr03263c

Science.gov (United States)

Pizzi, Andrea; Pigliacelli, Claudia; Gori, Alessandro; Nonappa; Ikkala, Olli; Demitri, Nicola; Terraneo, Giancarlo; Castelletto, Valeria; Hamley, Ian W.; Baldelli Bombelli, Francesca

2017-01-01

Amyloid peptides yield a plethora of interesting nanostructures though difficult to control. Here we report that depending on the number, position, and nature of the halogen atoms introduced into either one or both phenylalanine benzene rings of the amyloid β peptide-derived core-sequence KLVFF, four different architectures were obtained in a controlled manner. Our findings demonstrate that halogenation may develop as a general strategy to engineer amyloidal peptide self-assembly and obtain new amyloidal nanostructures. PMID:28696473

Spatial Atmospheric Pressure Atomic Layer Deposition of Tin Oxide as an Impermeable Electron Extraction Layer for Perovskite Solar Cells with Enhanced Thermal Stability.

Science.gov (United States)

Hoffmann, Lukas; Brinkmann, Kai O; Malerczyk, Jessica; Rogalla, Detlef; Becker, Tim; Theirich, Detlef; Shutsko, Ivan; Görrn, Patrick; Riedl, Thomas

2018-02-14

Despite the notable success of hybrid halide perovskite-based solar cells, their long-term stability is still a key-issue. Aside from optimizing the photoactive perovskite, the cell design states a powerful lever to improve stability under various stress conditions. Dedicated electrically conductive diffusion barriers inside the cell stack, that counteract the ingress of moisture and prevent the migration of corrosive halogen species, can substantially improve ambient and thermal stability. Although atomic layer deposition (ALD) is excellently suited to prepare such functional layers, ALD suffers from the requirement of vacuum and only allows for a very limited throughput. Here, we demonstrate for the first time spatial ALD-grown SnO x at atmospheric pressure as impermeable electron extraction layers for perovskite solar cells. We achieve optical transmittance and electrical conductivity similar to those in SnO x grown by conventional vacuum-based ALD. A low deposition temperature of 80 °C and a high substrate speed of 2.4 m min -1 yield SnO x layers with a low water vapor transmission rate of ∼10 -4 gm -2 day -1 (at 60 °C/60% RH). Thereby, in perovskite solar cells, dense hybrid Al:ZnO/SnO x electron extraction layers are created that are the key for stable cell characteristics beyond 1000 h in ambient air and over 3000 h at 60 °C. Most notably, our work of introducing spatial ALD at atmospheric pressure paves the way to the future roll-to-roll manufacturing of stable perovskite solar cells.

Tuning the magnetism of the top-layer FeAs on BaFe2As2 (001): First-principles study

Science.gov (United States)

Zhang, Bing-Jing; Liu, Kai; Lu, Zhong-Yi

2018-04-01

Magnetism may play an important role in inducing the superconductivity in iron-based superconductors. As a prototypical system, the surface of BaFe2As2 provides a good platform for studying related magnetic properties. We have designed systematic first-principles calculations to clarify the surface magnetism of BaFe2As2 (001), which previously has received little attention in comparison with surface structures and electronic states. We find that the surface environment has an important influence on the magnetic properties of the top-layer FeAs. For As-terminated surfaces, the magnetic ground state of the top-layer FeAs is in the staggered dimer antiferromagnetic (AFM) order, distinct from that of the bulk, while for Ba-terminated surfaces the collinear (single-stripe) AFM order is the most stable, the same as that in the bulk. When a certain coverage of Ba or K atoms is deposited onto the As-terminated surface, the calculated energy differences among different AFM orders for the top-layer FeAs on BaFe2As2 (001) can be much reduced, indicating enhanced spin fluctuations. To compare our results with available scanning tunneling microscopy (STM) measurements, we have simulated the STM images of several structural/magnetic terminations. Astonishingly, when the top-layer FeAs is in the staggered dimer AFM order, a stripe pattern appears in the simulated STM image even when the surface Ba atoms adopt a √{2 }×√{2 } structure, while a √{2 }×√{2 } square pattern comes out for the 1 ×1 full As termination. Our results suggest: (i) the magnetic state at the BaFe2As2 (001) surface can be quite different from that in the bulk; (ii) the magnetic properties of the top-layer FeAs can be tuned effectively by surface doping, which may likely induce superconductivity at the surface layer; (iii) both the surface termination and the AFM order in the top-layer FeAs can affect the STM image of BaFe2As2 (001), which needs to be taken into account when identifying the surface

Evaluation of modulators and electron-capture detectors for comprehensive two-dimensional GC of halogenated organic compounds

NARCIS (Netherlands)

Kristenson, E.M.; Korytar, P.; Danielsson, C.; Kallio, M.; Brandt, M.; Makela, J.; Vreuls, R.J.J.; Beens, J.; Brinkman, U.A.T.

2003-01-01

Different cryogenic and a heated GC×GC modulator(s) were evaluated and compared for the analysis of high-boiling halogenated compounds. The cryogenic modulators investigated were: (i) the longitudinally modulated cryogenic system; (ii) the liquid-nitrogen-cooled jet modulator (KT2001); (iii) a

The effect of sulphur-terminated GaAs substrates on the MOVPE growth of CuGaS{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Berndt, P.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)]. E-mail: pearl.berndt@nmmu.ac.za; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Branch, M.S. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Leitch, A.W.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Kirmse, H. [Institute of Physics, Chair of Crystallography, Humboldt University of Berlin, Berlin (Germany); Neumann, W. [Institute of Physics, Chair of Crystallography, Humboldt University of Berlin, Berlin (Germany); Weber, J. [Institute for Applied Physics-Semiconductor Physics, University of Technology, Dresden (Germany)

2007-05-31

In this study, various CuGaS{sub 2} layers were grown on GaAs (001) substrates using metalorganic vapour phase epitaxy, for the purpose of studying the effect of sulphur-termination of the substrate on layer quality. The resultant films were investigated using X-ray diffractometry, and transmission electron microscopy, with high-resolution transmission electron microscopy providing additional insights into crystallite growth on the control substrates. This paper will demonstrate that sulphur-termination limits substrate degradation. In the absence of sulphur-termination, atypical three-dimensional MOVPE growth is observed, with epitaxial crystallites varying in size from 10 nm to 200 nm. Substrate degradation inhibits lateral growth at the interface resulting in amorphous regions, cavities, and epitaxial crystallites demonstrating overgrowth into mushroom-like structures.

Theoretical and Experimental Study of the Friction Behavior of Halogen-Free Ionic Liquids in Elastohydrodynamic Regime

Directory of Open Access Journals (Sweden)

Karthik Janardhanan

2016-05-01

Full Text Available Ionic Liquids have emerged as effective lubricants and additives to lubricants, in the last decade. Halogen-free ionic liquids have recently been considered as more environmentally stable than their halogenated counterparts, which tend to form highly toxic and corrosive acids when exposed to moisture. Most of the studies using ionic liquids as lubricants or additives of lubricants have been done experimentally. Due to the complex nature of the lubrication mechanism of these ordered fluids, the development of a theoretical model that predicts the ionic liquid lubrication ability is currently one of the biggest challenges in tribology. In this study, a suitable and existing friction model to describe lubricating ability of ionic liquids in the elastohydrodynamic lubrication regime is identified and compared to experimental results. Two phosphonium-based, halogen-free ionic liquids are studied as additives to a Polyalphaolefin base oil in steel–steel contacts using a ball-on-flat reciprocating tribometer. Experimental conditions (speed, load and roughness are selected to ensure that operations are carried out in the elastohydrodynamic regime. Wear volume was also calculated for tests at high speed. A good agreement was found between the model and the experimental results when [THTDP][Phos] was used as an additive to the base oil, but some divergence was noticed when [THTDP][DCN] was added, particularly at the highest speed studied. A significant decrease in the steel disks wear volume is observed when 2.5 wt. % of the two ionic liquids were added to the base lubricant.

A New Contribution in Reducing Electric Field Distribution Within/Around Medium Voltage Underground Cable Terminations

Directory of Open Access Journals (Sweden)

S. S. Desouky

2017-10-01

Full Text Available Ιn medium voltage cables, the stress control layers play an important part in controlling the electric field distribution around the medium voltage underground cable terminations. Underground cable accessories, used in medium voltage cable systems, need a stress control tube in order to maintain and control the insulation level which is designed for long life times. The term “electrical stress control” refers to the cable termination analysis of optimizing the electrical stress in the area of insulation shield cutback to reduce the electrical field concentration at this point in order to reduce breakdown in the cable insulation. This paper presents the effect of some materials of different relative permittivities and geometrical regulation with the curved shape stress relief cones on the electric field distribution of cable termination. The optimization was done by comparing the results of eight materials used. Also, the effect of the change in the thickness of the stress control tube is presented. The modeling design is very important for engineers to find the optimal solution of terminator design of medium voltage cables. This paper also describes the evolution of stress control systems and their benefits. A developed program using Finite Element Method (FEM has calculated a numerical study to the stress control layering electric field distribution.

Contextual Feedback to Superficial Layers of V1

NARCIS (Netherlands)

Muckli, Lars; De Martino, Federico; Vizioli, Luca; Petro, Lucy S; Smith, Fraser W; Ugurbil, Kamil; Goebel, R.; Yacoub, Essa

2015-01-01

Neuronal cortical circuitry comprises feedforward, lateral, and feedback projections, each of which terminates in distinct cortical layers [1-3]. In sensory systems, feedforward processing transmits signals from the external world into the cortex, whereas feedback pathways signal the brain's

Radiocarbon content of synthetic and natural semi-volatile halogenated organic compounds

International Nuclear Information System (INIS)

Reddy, C.M.; Xu Li; Eglinton, T.I.; Boon, J.P.; Faulkner, D.J.

2002-01-01

New developments in molecular-level 14 C analysis techniques enable clues about natural versus commercial synthesis of trace organic contaminants. - Some halogenated organic compounds, such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polybrominated diphenyl ethers (PBDEs), have been suggested to have natural sources but separating these compounds from their commercially synthesized counterparts is difficult. Molecular-level 14 C analysis may be beneficial since most synthetic compounds are manufactured from petrochemicals ( 14 C-free) and natural compounds should have 'modern' or 'contemporary' 14 C levels. As a baseline study, we measured, for the first time, the 14 C abundance in commercial PCB and PBDE mixtures, a number of organochlorine pesticides, as well as one natural product 2-(3', 5'-dibromo-2'-methoxyphenoxy)-3,5-dibromoanisole. The latter compound was isolated from a marine sponge and is similar in structure to a PBDE. All of the synthetic compounds were 14 C-free except for the pesticide toxaphene, which had a modern 14 C abundance, as did the brominated natural compound. The result for toxaphene was not surprising since it was commercially synthesized by the chlorination of camphene derived from pine trees. These results suggest that measuring the 14 C content of halogenated organic compounds may be quite useful in establishing whether organic compounds encountered in the environment have natural or synthetic origins (or both) provided that any synthetic counterparts derive from petrochemical feedstock

Double Layer Dynamics in a Collisionless Magnetoplasma

DEFF Research Database (Denmark)

Iizuka, S.; Michelsen, Poul; Juul Rasmussen, Jens

and propagation of a double layer. The period of the oscillations is determined by the propagation length of the double layer. The current is limited during the propagation of the double layer by a growing negative potential barrier formed on the low potential tail. Similar phenomena appear when a potential......An experimental investigation of the dynamics of double layers is presented. The experiments are performed in a Q-machine plasma and the double layers are generated by applying a positive step potential to a cold collector plate terminating the plasma column. The double layer is created...... at the grounded plasma source just after the pulse is applied and it propagates towards the collector with a speed around the ion acoustic speed. When the collector is biased positively, large oscillations are obserced in the plasma current. These oscillations are found to be related to a recurring formation...

Quantized layer growth at liquid-crystal surfaces

DEFF Research Database (Denmark)

Ocko, B. M.; Braslau, A.; Pershan, P. S.

1986-01-01

of the specular reflectivity is consistent with a sinusoidal density modulation, starting at the surface and terminating abruptly, after an integral number of bilayers. As the transition is approached the number of layers increases in quantized steps from zero to five before the bulk undergoes a first...

Inhibition of presynaptic activity by zinc released from mossy fiber terminals during tetanic stimulation.

Science.gov (United States)

Minami, Akira; Sakurada, Naomi; Fuke, Sayuri; Kikuchi, Kazuya; Nagano, Tetsuo; Oku, Naoto; Takeda, Atsushi

2006-01-01

Zinc exists in high densities in the giant boutons of hippocampal mossy fibers. On the basis of the evidence that zinc decreases extracellular glutamate concentration in the hippocampus, the presynaptic action of zinc released from mossy fibers during high-frequency (tetanic) stimulation was examined using hippocampal slices. The increase in zinc-specific fluorescent signals was observed in both extracellular and intracellular compartments in the mossy fiber terminals during the delivery of tetanic stimuli (100 Hz, 1 sec) to the dentate granule cell layer, suggesting that zinc released from mossy fibers is immediately retaken up by mossy fibers. When mossy fiber terminals were preferentially double-stained with zinc and calcium indicators and tetanic stimuli (100 Hz, 1 sec) were delivered to the dentate granule cell layer, the increase in calcium orange signal during the stimulation was enhanced in mossy fiber terminals by addition of CaEDTA, a membrane-impermeable zinc chelator, and was suppressed by addition of zinc. The decrease in FM4-64 signal (vesicular exocytosis) during tetanic stimulation (10 Hz, 180 sec), which induced mossy fiber long-term potentiation, was also enhanced in mossy fiber terminals by addition of CaEDTA and was suppressed by addition of zinc. The present study demonstrates that zinc released from mossy fibers may be a negative-feedback factor against presynaptic activity during tetanic stimulation.

Photoinduced oxidation of sea salt halides by aromatic ketones: a source of halogenated radicals

Directory of Open Access Journals (Sweden)

A. Jammoul

2009-07-01

Full Text Available The interactions between triplet state benzophenone and halide anion species (Cl, Br and I have been studied by laser flash photolysis (at 355 nm in aqueous solutions at room temperature. The decay of the triplet state of benzophenone was followed at 525 nm. Triplet lifetime measurements gave rate constants, k_q (M⁻¹ s, close to diffusion controlled limit for iodide (~8×10⁹ M⁻¹ s, somewhat less for bromide (~3×10⁸ M⁻¹ s and much lower for chloride (<10⁶ M⁻¹ s. The halide (X⁻ quenches the triplet state; the resulting product has a transient absorption at 355 nm and a lifetime much longer than that of the benzophenone triplet state, is formed. This transient absorption feature matches those of the corresponding radical anion (X₂. We therefore suggest that such reactive quenching is a photosensitized source of halogen in the atmosphere or the driving force for the chemical oxidation of the oceanic surface micro layer.

Actinic-radiation curable polymers prepared from a reactive polymer, halogenated cyclic anhydride and glycidyl ester

International Nuclear Information System (INIS)

Pastor, S.D.

1979-01-01

A novel class of photosensitive polymers are disclosed which are prepared by the reaction, preferably in the presence of a catalyst, of a reactive polymer, a halogenated cyclic anhydride and glycidyl ester of an alpha, beta-unsaturated carboxylic acid. These polymers are capable of undergoing vinyl-type polymerization when exposed to actinic radiation

The detection of some halogenated phenols and nitrophenols in thin-layer chromatography by means of bromine

NARCIS (Netherlands)

Tadema, G.; Batelaan, P.H.

1968-01-01

A method is described for the detection of halogeno- and nitro-phenols in sub-microgram quantities. Theses compounds are made visible by exposure of the developed thin layer plates to bromine vapour and subsequent spraying with an aqueous solution of potassium iodide or an ethanolic solution of

Photochemistry of xenon-halogen Van der Waals complexes (X2 = Cl2, Br2, I2): evidence for the intermediate states in the (Xe-X2)*→ XeX* + X reaction

International Nuclear Information System (INIS)

Boivineau, Michel

1987-01-01

This research thesis addresses the reactivity of excited states of xenon-halogen Van der Waals complexes (Cl 2 , Br 2 , I 2 ) submitted to a multi-photonic excitation. The objective of this study is, by means of a specific experimental approach, to highlight the R*+ X 2 *- to better understand the reaction mechanism, and to study the reactivity of rare gas/halogen systems depending on the halogen nature. After having reported a bibliographical study on each studied system, the author describes the experimental system, reports and discusses experimental results obtained on the different complex systems (chlorine-, bromine- or iodine-based). He finally comments a possible and original application of these works in the development of an excimer laser with a new active medium (the rare gas/halogen Van der Waals complex) which would allow a continuous operation and an easy discharge production [fr

The effect of halogen hetero-atoms on the vapor pressures and thermodynamics of polycyclic aromatic compounds measured via the Knudsen effusion technique

International Nuclear Information System (INIS)

Goldfarb, Jillian L.; Suuberg, Eric M.

2008-01-01

Knowledge of vapor pressures of high molar mass organics is essential to predicting their behavior in combustion systems as well as their fate and transport within the environment. This study involved polycyclic aromatic compounds (PACs) containing halogen hetero-atoms, including bromine and chlorine. The vapor pressures of eight PACs, ranging in molar mass from (212 to 336) g . mol -1 , were measured using the isothermal Knudsen effusion technique over the temperature range of (296 to 408) K. These compounds included those with few or no data available in the literature, namely: 1,4-dibromonaphthalene, 5-bromoacenaphthene, 9-bromoanthracene, 1,5-dibromoanthracene, 9,10-dibromoanthracene, 2-chloroanthracene, 9,10-dichloroanthracene, and 1-bromopyrene. Enthalpies of sublimation of these compounds were determined via application of the Clausius-Clapeyron equation. An analysis is presented on the effects of the addition of halogen hetero-atoms to pure polycyclic aromatic hydrocarbons using these data as well as available literature data. As expected, the addition of halogens onto these PACs increases their enthalpies of sublimation and decreases their vapor pressures as compared to the parent compounds

A Comparison of the Shear Bond Strength of Orthodontic Brackets Bonded With Light-Emitting Diode and Halogen Light-Curing Units

Directory of Open Access Journals (Sweden)

SM. Abtahi

2006-09-01

Full Text Available Statement of the problem: Various methods such as light emitting diode (LED have been used to enhance the polymerization of resin-based orthodontic adhesives. There is a lack of information on the advantages and disadvantages of different light curing systems.Purpose: The aim of this study was to compare the effect of LED and halogen light curing systems on the shear bond strength of orthodontic brackets.Materials and Methods: Forty extracted human premolars were etched with 37% phosphoric acid and cleansed with water spray and air dried. The sealant was applied on the tooth surface and the brackets were bonded using Transbond adhesive (3M Unitek,Monrovia, Calif. Adhesives were cured for 40 and 20 seconds with halogen (Blue Light, APOZA, Taiwan and LED (Blue dent, Smart, Yugoslavia light-curing systems,respectively. Specimens were thermocycled 2500 times (from 5 to 55 °C and the shear bond strength of the adhesive system was evaluated with an Universal testing machine (Zwick GmbH, Ulm, Germany at a crosshead speed of 1 mm/min until the bracketswere detached from the tooth. Adhesive remnant index (ARI scores were determined after bracket failure. The data were submitted to statistical analysis, using Mann-Whitney analysis and t-test.Results: No significant difference was found in bond strength between the LED and halogen groups (P=0.12. A significant difference was not observed in the adhesive remnant index scores between the two groups (P=0.97.Conclusion: Within the limitations of this in vitro study, the shear bond strength of resin-based orthodontic adhesives cured with a LED was statistically equivalent to those cured with a conventional halogen-based unit. LED light-curing units can be suggested for the polymerization of orthodontic bonding adhesives.

Halogenated greenhouse gases at the Swiss High Alpine Site of Jungfraujoch (3580 m asl): Continuous measurements and their use for regional European source allocation

Science.gov (United States)

Reimann, Stefan; Schaub, Daniel; Stemmler, Konrad; Folini, Doris; Hill, Matthias; Hofer, Peter; Buchmann, Brigitte; Simmonds, Peter G.; Greally, Brian R.; O'Doherty, Simon

2004-03-01

At the high Alpine site of Jungfraujoch (3580 m asl), 23 halogenated greenhouse gases are measured quasi-continuously by gas chromatography-mass spectrometry (GCMS). Measurement data from the years 2000-2002 are analyzed for trends and pollution events. Concentrations of the halogenated trace gases, which are already controlled in industrialized countries by the Montreal Protocol (e.g., CFCs) were at least stable or declining. Positive trends in the background concentrations were observed for substances which are used as CFC-substitutes (hydrofluorocarbons, hydrochlorofluorocarbons). Background concentrations of the hydrofluorocarbons at the Jungfraujoch increased from January 2000 until December 2002 as follows: HFC 134a (CF3CH2F) from 15 to 27 ppt, HFC 125 (CF3CHF2) from 1.4 to 2.8 ppt, and HFC 152a (CHF2CH3) from 2.3 to 3.2 ppt. For HFC 152a, a distinct increase of its concentration magnitude during pollution events was observed from 2000 to 2002, indicating rising European emissions for this compound. Background concentrations of all measured compounds were in good agreement with similar measurements at Mace Head, Ireland. On the other hand, peak concentrations were significantly higher at the Jungfraujoch. This finding is due to the proximity to potent European sources, foremost in southern Europe. The average ratio of halocarbons versus carbon monoxide (CO) concentrations above their baseline values was used to estimate source strengths for the part of Europe which most influences the Jungfraujoch during pollution events. HFCs emission estimates from Jungfraujoch tend to be higher than figures at Mace Head (Ireland) from the end of the 1990s, which either reflects the increased use of these compounds or the closer location of Jungfraujoch to major southern European sources. Transport of polluted European boundary layer air masses to the high Alpine site was observed especially during frontal passages, foehn events, and thermal lifting of air masses in summer

Experimental investigation of halogen-bond hard-soft acid-base complementarity.

Science.gov (United States)

Riel, Asia Marie S; Jessop, Morly J; Decato, Daniel A; Massena, Casey J; Nascimento, Vinicius R; Berryman, Orion B

2017-04-01

The halogen bond (XB) is a topical noncovalent interaction of rapidly increasing importance. The XB employs a `soft' donor atom in comparison to the `hard' proton of the hydrogen bond (HB). This difference has led to the hypothesis that XBs can form more favorable interactions with `soft' bases than HBs. While computational studies have supported this suggestion, solution and solid-state data are lacking. Here, XB soft-soft complementarity is investigated with a bidentate receptor that shows similar associations with neutral carbonyls and heavy chalcogen analogs. The solution speciation and XB soft-soft complementarity is supported by four crystal structures containing neutral and anionic soft Lewis bases.

Changes in patterns of persistent halogenated compounds through a pelagic food web in the Baltic Sea

DEFF Research Database (Denmark)

Stephansen, Diana Agnete; Svendsen, Tore Christian; Vorkamp, Katrin

2012-01-01

The concentrations and patterns of persistent halogenated compounds (PHCs), including polychlorinated biphenyls (PCBs), DDT, hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and polybrominated diphenyl ethers (PBDEs) were examined in a pelagic food web from the southern Baltic Sea consisting...... for the assessment of PHC patterns, e.g. for tracing migratory fish....

Preparation and properties studies of halogen-free flame retardant form-stable phase change materials based on paraffin/high density polyethylene composites

International Nuclear Information System (INIS)

Cai Yibing; Wei Qufu; Huang Fenglin; Gao Weidong

2008-01-01

The halogen-free flame retardant form-stable phase change materials (PCM) based on paraffin/high density polyethylene (HDPE) composites were prepared by using twin-screw extruder technique. The structures and properties of the form-stable PCM composites based on intumescent flame retardant system with expandable graphite (EG) and different synergistic additives, such as ammonium polyphosphate (APP) and zinc borate (ZB) were characterized by scanning electronic microscope (SEM), thermogravimetric analyses (TGA), dynamic Fourier-transform infrared (FTIR) spectra, differential scanning calorimeter (DSC) and Cone calorimeter test. The TGA results showed that the halogen-free flame retardant form-stable PCM composites produced a larger amount of charred residue at 700 deg. C, although the onset of weight loss of the halogen-free flame retardant form-stable PCM composites occurred at a lower temperature due to the thermal decomposition of flame retardant. The DSC measurements indicated that the additives of flame retardant had little effect on the thermal energy storage property, and the temperatures of phase change peaks and the latent heat of the paraffin showed better occurrence during the freezing process. The dynamic FTIR monitoring results revealed that the breakdowns of main chains (HDPE and paraffin) and formations of various residues increased with increasing thermo-oxidation temperature. It was also found from the Cone calorimeter tests that the peak of heat release rate (PHRR) decreased significantly. Both the decrease of the PHRR and the structure of charred residue after combustion indicated that there was a synergistic effect between the EG and APP, contributing to the improved flammability of the halogen-free flame retardant form-stable PCM composites

Operation mode switchable charge-trap memory based on few-layer MoS2

Science.gov (United States)

Hou, Xiang; Yan, Xiao; Liu, Chunsen; Ding, Shijin; Zhang, David Wei; Zhou, Peng

2018-03-01

Ultrathin layered two-dimensional (2D) semiconductors like MoS2 and WSe2 have received a lot of attention because of their excellent electrical properties and potential applications in electronic devices. We demonstrate a charge-trap memory with two different tunable operation modes based on a few-layer MoS2 channel and an Al2O3/HfO2/Al2O3 charge storage stack. Our device shows excellent memory properties under the traditional three-terminal operation mode. More importantly, unlike conventional charge-trap devices, this device can also realize the memory performance with just two terminals (drain and source) because of the unique atomic crystal electrical characteristics. Under the two-terminal operation mode, the erase/program current ratio can reach up to 104 with a stable retention property. Our study indicates that the conventional charge-trap memory cell can also realize the memory performance without the gate terminal based on novel two dimensional materials, which is meaningful for low power consumption and high integration density applications.

Large area inkjet printing for organic photovoltaics and organic light emitting diodes using non-halogenated ink formulations

NARCIS (Netherlands)

Eggenhuisen, T.M.; Coenen, M.J.J.; Slaats, M.W.L.; Groen, W.A.

2014-01-01

The transfer of laboratory scale solution processing of organic electronics to large area roll-to-roll production requires the use of up-scalable deposition techniques. Furthermore, industrial production demands the omission of halogenated and other harmful solvents. Here, the authors discuss large

Hybrid solar cells based on CuInS2 and organic buffer-sensitizer layers

International Nuclear Information System (INIS)

Bereznev, S.; Koeppe, R.; Konovalov, I.; Kois, J.; Guenes, S.; Opik, A.; Mellikov, E.; Sariciftci, N.S.

2007-01-01

Hybrid solar cells on the basis of CuInS 2 (CIS) photoabsorber on Cu-tape (CISCuT) in combination with organic buffer layers of Zn-phthalocyanine (ZnPc), ZnPc:fullerene (ZnPc:C 60 ) composite and conductive polymer buffer layers of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrenesulfonate (PSS) were prepared using vacuum evaporation and spin-casting techniques. To prepare solar cells with an active area of 2 cm 2 , the appropriate deposition parameters and thickness of ZnPc, ZnPc:C 60 and PEDOT-PSS layers were selected experimentally. For preparation of semitransparent contact-window layers, chromium and gold were evaporated on the surface of ZnPc, ZnPc:C 60 and PEDOT-PSS films. It was found that an intermediate chromium layer improves PV properties of the structures with organic buffer layers. The photosensitivity at small illumination intensities of complete structures with ZnPc and ZnPc:C 60 layers increased more than one order of magnitude in comparison with the structures where the PEDOT-PSS buffer layer was deposited. The presence of C 60 in the composite-buffer layer results in increased photoconductivity. The best structure with composite ZnPc:C 60 buffer layer showed an open-circuit voltage of 560 mV, a short-circuit current density of around 10 mA/cm 2 and a photoconversion efficiency of around 3.3% under the light illumination with an intensity of 100 mW/cm 2 from a tungsten-halogen lamp. The low transmission of the semitransparent chromium-gold window layer is the reason for relatively low current density

Provenance of the K/T boundary layers

International Nuclear Information System (INIS)

Hildebrand, A.R.; Boynton, W.V.

1988-01-01

An array of chemical, physical and isotopic evidence indicates that an impact into oceanic crust terminated the Cretaceous Period. Approximately 1500 cu km of debris, dispersed by the impact fireball, fell out globally in marine and nonmarine environments producing a 2 to 4 mm thick layer (fireball layer). In North American locales, the fireball layer overlies a 15 to 25 mm thick layer of similar but distinct composition. This 15 to 25 mm layer (ejecta layer) may represent approximately 1000 cu km of lower energy ejecta from a nearby impact site. Isotopic and chemical evidence supports a mantle provenance for the bulk of the layers. The extraordinary REE pattern of the boundary clays was modelled as a mixture of oceanic crust, mantle, and approximately 10 percent continental material. The results are presented. If the siderophiles of the ejecta layer were derived solely from the mantle, a test may be available to see if the siderophile element anomaly of the fireball layer had an extraterrestrial origin. Radiogenic Os-187 is depleted in the mantle relative to an undifferentiated chondritic source. Os-187/Os-186 ratios of 1.049 and 1.108 were calculated for the ejecta and fireball layers, respectively

Halogenated organic species over the tropical South American rainforest

Directory of Open Access Journals (Sweden)

S. Gebhardt

2008-06-01

Full Text Available Airborne measurements of the halogenated trace gases methyl chloride, methyl bromide and chloroform were conducted over the Atlantic Ocean and about 1000 km of pristine tropical rainforest in Suriname and French Guyana (3–6° N, 51–59° W in October 2005. In the boundary layer (0–1.4 km, maritime air masses, advected over the forest by southeasterly trade winds, were measured at various distances from the coast. Since the organohalogens presented here have relatively long atmospheric lifetimes (0.4–1.0 years in comparison to the advection times from the coast (1–2 days, emissions will accumulate in air traversing the rainforest. The distributions of methyl chloride, methyl bromide and chloroform were analyzed as a function of time the air spent over land and the respective relationship used to determine net fluxes from the rainforest for one week within the long dry season.

Net fluxes from the rainforest ecosystem have been calculated for methyl chloride and chloroform as 9.5 (±3.8 2σ and 0.35 (±0.15 2σμg m^-2 h⁻¹, respectively. No significant flux was observed for methyl bromide within the limits of these measurements.

The global budget of methyl chloride contains large uncertainties, in particular with regard to a possible source from tropical vegetation. Our measurements are used in a large-scale approach to determine the net flux from a tropical ecosystem to the planetary boundary layer. The obtained global net flux of 1.5 (±0.6 2σ Tg yr^-1 for methyl chloride is at the lower end of current estimates for tropical vegetation sources, which helps to constrain the range of tropical sources and sinks (0.82 to 8.2 Tg yr^-1 from tropical plants, 0.03 to 2.5 Tg yr^-1 from senescent/dead leaves and a sink of 0.1 to 1.6 Tg yr^-1 by soil uptake. Nevertheless, these results show that the contribution of the rainforest ecosystem is the major source in the

Reactivity of N-heterocyclic carbene-pyridine palladacyclopentadiene complexes toward halogen addition. The unpredictable course of the reaction.

Science.gov (United States)

Visentin, Fabiano; Santo, Claudio; Scattolin, Thomas; Demitri, Nicola; Canovese, Luciano

2017-08-08

As an extension of a previously published work we have reacted some palladacyclopentadiene complexes stabilized by bidentate N-heterocyclic carbene-pyridine or monodentate N-heterocyclic carbene-pyridine and isocyanide ligands with the halogens I 2 and Br 2 . All the bidentate and monodentate complexes react with halogens to give at first the expected σ-coordinated butadienyl fragment. However, two of the less hindered NHC carbene-pyridine bidentate butadienyl iodo derivatives undergo a further rearrangement and novel Pd(ii) complexes characterized by a ten term coordinative ring were isolated and characterized. In the most favorable case we were able to carry out the kinetics of rearrangement and measure its reaction rate. Moreover, we have surmised a plausible mechanism on the basis of a dedicated computational approach and in one case the surprising structure characterized by the ten term coordinative ring was resolved by X-ray diffraction.

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1978--February 14, 1979

International Nuclear Information System (INIS)

Rack, E.P.

1979-02-01

High energy reactions of halogen atoms or ions, activated by nuclear transformations, were studied in gaseous, high pressure and condensed phase saturated and unsaturated hydrocarbons, halomethanes and other organic systems in order to better understand the mechanisms and dynamics of high energy monovalent species. The experimental and theoretical program consists of six interrelated areas: (1) the reactions of iodine with alkenes and alkynes activated by radiative neutron capture and isomeric transition in low pressure gaseous systems employing additives and rare gas moderators, high pressure and liquid systems; (2) the gas to condensed state transition in halogen high chemistry, involving bromine activated by the (n,γ) and (I.T.) processes in ethane was investigated in more detail; (3) systematics of halogen hot atom reactions. The reactions of 80 Br/sup m/, 80 Br, 82 Br/sup m/ + 82 Br, 82 Br, 128 I, 130 I, and 130 I/sup m/ + 130 I activated by radiative neutron capture or isomeric transition in hydrocarbons and halo-substituted alkanes in low pressure and high pressure gaseous systems employing additives and rare gas moderators; (4) kinetic theory applications of high energy reactions and mathematical development of caging mechanisms were developed; (5) the sterochemistry of 38 Cl substitution reactions involving diastereomeric 1,2-dichloro-1,2-difluorethane in liquid mixtures was completed, suggesting that the stereochemical course of the substitution process is controlled by the properties of the solvent molecules; and (6) the applications of high energy chemistry techniques and theory to neutron activation analysis of biological systems was continued, especially involving aluminum and vanadium trace determinations

Morphology and distribution of chandelier cell axon terminals in the mouse cerebral cortex and claustroamygdaloid complex.

Science.gov (United States)

Inda, M C; DeFelipe, J; Muñoz, A

2009-01-01

Chandelier cells represent a unique type of cortical gamma-aminobutityric acidergic interneuron whose axon terminals (Ch-terminals) only form synapses with the axon initial segments of some pyramidal cells. Here, we have used immunocytochemistry for the high-affinity plasma membrane transporter GAT-1 and the calcium-binding protein parvalbumin to analyze the morphology and distribution of Ch-terminals in the mouse cerebral cortex and claustroamygdaloid complex. In general, 2 types of Ch-terminals were distinguished on the basis of their size and the density of the axonal boutons that made up the terminal. Simple Ch-terminals were made up of 1 or 2 rows of labeled boutons, each row consisting of only 3-5 boutons. In contrast, complex Ch-terminals were tight cylinder-like structures made up of multiple rows of boutons. Simple Ch-terminals were detected throughout the cerebral cortex and claustroamygdaloid complex, the complex type was only occasionally found in certain regions, whereas in others they were very abundant. These results indicate that there are substantial differences in the morphology and distribution of Ch-terminals between different areas and layers of the mouse cerebral cortex. Furthermore, we suggest that the distribution of complex Ch-terminals may be related to the developmental origin of the different brain regions analyzed.

Physics of tokamak scrape-off layer confinement

International Nuclear Information System (INIS)

Cohen, R.H.

1993-01-01

Confinement in the scrape-off layer (SOL) of a tokamak is believed to be governed by classical flows along magnetic field lines terminated by sheaths, and turbulent transport across field lines. In this paper we review how these two effects conspire to establish the width of the SOL, and survey recent and ongoing work on mechanisms for turbulence in SOL's. The beneficial relationship between scrape-off layer turbulence in mitigating the heat flux density on divertors is noted, and tactics for actively altering SOL confinement so as to reduce the heat flux density are discussed

Nuclear radiation detector. Realization and study of the G.M. counters with halogens, the multiples anodes

International Nuclear Information System (INIS)

Sekhavat, A.

1975-01-01

A substantial improvement of the halogene GEIGER-MULLER counters properties has been carried out by the research of new anode forms. This amelioration has been revealed by the comparison of the new counters with the classical ones, absolutely identical as to their size and production. The anodes alone are different

Synthesis of All-carbon Chains and Nanoparticles by Chemical Transformation of Halogenated Hydrocarbons at Low Temperatures

Czech Academy of Sciences Publication Activity Database

Kavan, Ladislav

č. 196 (2001), s. 22-38 ISSN 0371-5345 R&D Projects: GA ČR GA203/98/1168; GA ČR GA203/99/1015; GA ČR GA203/00/0634 Institutional research plan: CEZ:AV0Z4040901 Keywords : halogenated hydrocarbon * electrochemical carbon * fullerenes Subject RIV: CG - Electrochemistry

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.

Nucleation and Early Stages of Layer-by-Layer Growth of Metal Organic Frameworks on Surfaces

Science.gov (United States)

2015-01-01

High resolution atomic force microscopy (AFM) is used to resolve the evolution of crystallites of a metal organic framework (HKUST-1) grown on Au(111) using a liquid-phase layer-by-layer methodology. The nucleation and faceting of individual crystallites is followed by repeatedly imaging the same submicron region after each cycle of growth and we find that the growing surface is terminated by {111} facets leading to the formation of pyramidal nanostructures for [100] oriented crystallites, and triangular [111] islands with typical lateral dimensions of tens of nanometres. AFM images reveal that crystallites can grow by 5–10 layers in each cycle. The growth rate depends on crystallographic orientation and the morphology of the gold substrate, and we demonstrate that under these conditions the growth is nanocrystalline with a morphology determined by the minimum energy surface. PMID:26709359

Selective Halogen-Lithium Exchange of 1,2-Dihaloarenes for Successive [2+4] Cycloadditions of Arynes and Isobenzofurans

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Shohei Eda

2015-10-01

Full Text Available Successive [2+4] cycloadditions of arynes and isobenzofurans by site-selective halogen-lithium exchange of 1,2-dihaloarenes were developed, allowing the rapid construction of polycyclic compounds which serve as a useful synthetic intermediates for the preparation of various polyacene derivatives.

Simple synthesis of multi-halogen pyrazino [1,2-a]indole-1,8(2H,5aH)-dione

Energy Technology Data Exchange (ETDEWEB)

Yang, Rui Xia; Zhao, Yu Cheng; Kong, Ling Bin; Yan, Sheng Jiao; Lin, Jun [Key Laboratory of Medicinal Chemistry for Natural Resource (Yunnan University), Ministry Education, School of Chemical Science and Technology, Yunnan University, Kunming (China)

2016-10-15

A concise and efficient one-pot synthesis of multi-halogen pyrazino[1,2-a]indole-1,8(2H,5aH)-dione (MHPID) derivatives by the reaction of an enamino ester with multi-halogen benzoquinone derivatives is described. MHPIDs 3a–3d were obtained with good yields (78–83%) by refluxing enamino esters 1a and 1b and tetrahalogen-1,4-benzoquinones 2a and 2b for 24 h without the use of catalysts. Compounds 3e–3p were also obtained with excellent yields (69–92%) via the reaction of the phenyl-substituted enamino esters 1c–1h with tetrahalogen-1,4-benzoquinones 2a and 2b in CH3CN catalyzed by Cs2CO3. These two protocols are efficient and effective for the synthesis of MHPIDs.

Tracing groundwater with low-level detections of halogenated VOCs in a fractured carbonate-rock aquifer, Leetown Science Center, West Virginia, USA

Science.gov (United States)

Plummer, Niel; Sibrell, Philip L.; Casile, Gerolamo C.; Busenberg, Eurybiades; Hunt, Andrew G.; Schlosser, Peter

2013-01-01

Measurements of low-level concentrations of halogenated volatile organic compounds (VOCs) and estimates of groundwater age interpreted from 3H/3He and SF6 data have led to an improved understanding of groundwater flow, water sources, and transit times in a karstic, fractured, carbonate-rock aquifer at the Leetown Science Center (LSC), West Virginia. The sum of the concentrations of a set of 16 predominant halogenated VOCs (TDVOC) determined by gas chromatography with electron-capture detector (GC–ECD) exceeded that possible for air–water equilibrium in 34 of the 47 samples (median TDVOC of 24,800 pg kg−1), indicating that nearly all the water sampled in the vicinity of the LSC has been affected by addition of halogenated VOCs from non-atmospheric source(s). Leakage from a landfill that was closed and sealed nearly 20 a prior to sampling was recognized and traced to areas east of the LSC using low-level detection of tetrachloroethene (PCE), methyl chloride (MeCl), methyl chloroform (MC), dichlorodifluoromethane (CFC-12), and cis-1,2-dichloroethene (cis-1,2-DCE). Chloroform (CHLF) was the predominant VOC in water from domestic wells surrounding the LSC, and was elevated in groundwater in and near the Fish Health Laboratory at the LSC, where a leak of chlorinated water occurred prior to 2006. The low-level concentrations of halogenated VOCs did not exceed human or aquatic-life health criteria, and were useful in providing an awareness of the intrinsic susceptibility of the fractured karstic groundwater system at the LSC to non-atmospheric anthropogenic inputs. The 3H/3He groundwater ages of spring discharge from the carbonate rocks showed transient behavior, with ages averaging about 2 a in 2004 following a wet climatic period (2003–2004), and ages in the range of 4–7 a in periods of more average precipitation (2008–2009). The SF6 and CFC-12 data indicate older water (model ages of 10s of years or more) in the low-permeability shale of the Martinsburg

Theoretical investigation of the use of nanocages with an adsorbed halogen atom as anode materials in metal-ion batteries.

Science.gov (United States)

Razavi, Razieh; Abrishamifar, Seyyed Milad; Rajaei, Gholamreza Ebrahimzadeh; Kahkha, Mohammad Reza Rezaei; Najafi, Meysam

2018-02-21

The applicability of C 44 , B 22 N 22 , Ge 44 , and Al 22 P 22 nanocages, as well as variants of those nanocages with an adsorbed halogen atom, as high-performance anode materials in Li-ion, Na-ion, and K-ion batteries was investigated theoretically via density functional theory. The results obtained indicate that, among the nanocages with no adsorbed halogen atom, Al 22 P 22 would be the best candidate for a novel anode material for use in metal-ion batteries. Calculations also suggest that K-ion batteries which utilize these nanocages as anode materials would give better performance and would yield higher cell voltages than the corresponding Li-ion and Na-ion batteries with nanocage-based anodes. Also, the results for the nanocages with an adsorbed halogen atom imply that employing them as anode materials would lead to higher cell voltages and better metal-ion battery performance than if the nanocages with no adsorbed halogen atom were to be used as anode materials instead. Results further implied that nanocages with an adsorbed F atom would give higher cell voltages and better battery performance than nanocages with an adsorbed Cl or Br atom. We were ultimately able to conclude that a K-ion battery that utilized Al 21 P 22 with an adsorbed F atom as its anode material would afford the best metal-ion battery performance; we therefore propose this as a novel highly efficient metal-ion battery. Graphical abstract The results of a theoretical investigation indicated that Al 22 P 22 is a better candidate for a high-performance anode material in metal-ion batteries than Ge 44 is. Calculations also showed that K-ion batteries with nanocage-based anodes would produce higher cell voltages and perform better than the equivalent Li-ion and Na-ion batteries with nanocage-based anodes, and that anodes based on nanocages with an adsorbed F atom would perform better than anodes based on nanocages with an adsorbed Cl or Br atom.

Layer-by-Layer Method for the Synthesis and Growth of Surface Mounted Metal-Organic Frameworks (SURMOFs

Directory of Open Access Journals (Sweden)

Osama Shekhah

2010-02-01

Full Text Available A layer-by-layer method has been developed for the synthesis of metal-organic frameworks (MOFs and their deposition on functionalized organic surfaces. The approach is based on the sequential immersion of functionalized organic surfaces into solutions of the building blocks of the MOF, i.e., the organic ligand and the inorganic unit. The synthesis and growth of different types of MOFs on substrates with different functionalization, like COOH, OH and pyridine terminated surfaces, were studied and characterized with different surface characterization techniques. A controlled and highly oriented growth of very homogenous films was obtained using this method. The layer-by-layer method offered also the possibility to study the kinetics of film formation in more detail using surface plasmon resonance and quartz crystal microbalance. In addition, this method demonstrates the potential to synthesize new classes of MOFs not accessible by conventional methods. Finally, the controlled growth of MOF thin films is important for many applications like chemical sensors, membranes and related electrodes.

Temperature dependent halogen activation by N2O5 reactions on halide-doped ice surfaces

Directory of Open Access Journals (Sweden)

J. A. Thornton

2012-06-01

Full Text Available We examined the reaction of N2O5 on frozen halide salt solutions as a function of temperature and composition using a coated wall flow tube technique coupled to a chemical ionization mass spectrometer (CIMS. The molar yield of photo-labile halogen compounds was near unity for almost all conditions studied, with the observed reaction products being nitryl chloride (ClNO2 and/or molecular bromine (Br2. The relative yield of ClNO2 and Br2 depended on the ratio of bromide to chloride ions in the solutions used to form the ice. At a bromide to chloride ion molar ratio greater than 1/30 in the starting solution, Br2 was the dominant product otherwise ClNO2 was primarily produced on these near pH-neutral brines. We demonstrate that the competition between chlorine and bromine activation is a function of the ice/brine temperature presumably due to the preferential precipitation of NaCl hydrates from the brine below 250 K. Our results provide new experimental confirmation that the chemical environment of the brine layer changes with temperature and that these changes can directly affect multiphase chemistry. These findings have implications for modeling air-snow-ice interactions in polar regions and likely in polluted mid-latitude regions during winter as well.

Atomic layer deposition of TiO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Tallarida, Massimo; Dessmann, Nils; Staedter, Matthias; Friedrich, Daniel; Michling, Marcel; Schmeisser, Dieter [BTU-Cottbus, Konrad-Wachsmann-Allee 17, 03046 Cottbus (Germany)

2011-07-01

We present a study of the initial growth of TiO{sub 2} on Si(111) by atomic layer deposition (ALD). The Si substrate was etched with NH{sub 4}F before ALD to remove the native oxide film and to produce a Si-H termination. In-situ experiments by means of photoemission and X-ray absorption spectroscopy were conducted with synchrotron radiation on Ti-oxide films produced using Ti-tetra-iso-propoxide (TTIP) and water as precursors. O 1s, Ti 2p, C 1s, and S i2p core level, and O 1s and Ti 2p absorption edges show the transition of the Ti-oxide properties during the first layers. The growth starts with a very small growth rate (0.03 nm/cycle) due to the growth inhibition of the Si-H termination and proceeds with higher growth rate (0.1 nm/cycle) after 1.5 nm Ti-oxide has been deposited.

New Route to Synthesize Surface Organometallic Complexes (SOMC): An Approach by Alkylating Halogenated Surface Organometallic Fragments

KAUST Repository

Hamieh, Ali Imad Ali

2017-01-01

The aim of this thesis is to explore new simpler and efficient routes for the preparation of surface organometallic complexes (SOMC) for the transformation of small organic molecules to valuable products. The key element in this new route relies on surface alkylation of various halogenated surface coordination complexes or organometallic fragments (SOMF).

New Route to Synthesize Surface Organometallic Complexes (SOMC): An Approach by Alkylating Halogenated Surface Organometallic Fragments

KAUST Repository

Hamieh, Ali Imad

2017-02-01

The aim of this thesis is to explore new simpler and efficient routes for the preparation of surface organometallic complexes (SOMC) for the transformation of small organic molecules to valuable products. The key element in this new route relies on surface alkylation of various halogenated surface coordination complexes or organometallic fragments (SOMF).

Spectrally dependent photovoltages in Schottky photodiode based on (100) B-doped diamond

Science.gov (United States)

Čermák, Jan; Koide, Yasuo; Takeuchi, Daisuke; Rezek, Bohuslav

2014-02-01

Spectrally and spatially resolved photovoltages were measured by Kelvin probe force microscopy (KPFM) on a Schottky photo-diode made of a 4 nm thin tungsten-carbide (WC) layer on a 500 nm oxygen-terminated boron-doped diamond epitaxial layer (O-BDD) that was grown on a Ib (100) diamond substrate. The diode was grounded by the sideways ohmic contact (Ti/WC), and the semitransparent Schottky contact was let unconnected. The electrical potentials across the device were measured in dark (only 650 nm LED of KPFM being on), under broad-band white light (halogen lamp), UV (365 nm diode), and deep ultraviolet (deuterium lamp) illumination. Illumination induced shift of the electrical potential remains within 210 mV. We propose that the photovoltage actually corresponds to a shift of Fermi level inside the BDD channel and thereby explains orders of magnitude changes in photocurrent.

Layer-by-layer polyelectrolyte films for contact electric energy harvesting

International Nuclear Information System (INIS)

Guo, X D; Helseth, L E

2015-01-01

We report how self-assembly of polyelectrolyte thin films alters the contact electrification of polyimide polymer films used in contact based triboelectric energy harvesting systems. Polyimide films of the same size do produce a very small current when brought into contact. However, by covering one of the polyimide films with a polyelectrolyte thin film terminated by positively charged poly(allylamine hydrochloride) (PAH), the current is reversed and a much larger current and voltage are generated upon contact with the other polyimide film. A similar increase in contact current is not seen for polyelectrolyte thin films terminated by the negatively charged poly(sodium 4-styrenesulfonate). The PAH-terminated Kapton films are used to create an energy harvesting system providing a voltage of about 60 V and a current of 10 μA. At an average power of 11 μW for a load resistance of 100 MΩ, the energy harvester is able to power several light emitting diodes. Further studies on the contact electrification of the polyelectrolyte demonstrate that nanostructuring of the polymer surface using reactive ion etching does not give rise to polarity reversal. This is explained as hidden pockets of charge not accessible to PAH molecules, but which become accessible when the polymer is put under stress. Although the current originating for a PAH-terminated multilayer film does initially have the opposite sign to that of bare polyimide, it is found that the polarity will switch after subjecting it to a periodical mechanical force. Characteristic changes in current signatures associated with the switch are found, and are interpreted as mechanical interpenetration of the charged layers. (paper)

Reversible Capture and Release of Cl2 and Br2 with a Redox-Active Metal-Organic Framework.

Science.gov (United States)

Tulchinsky, Yuri; Hendon, Christopher H; Lomachenko, Kirill A; Borfecchia, Elisa; Melot, Brent C; Hudson, Matthew R; Tarver, Jacob D; Korzyński, Maciej D; Stubbs, Amanda W; Kagan, Jacob J; Lamberti, Carlo; Brown, Craig M; Dincă, Mircea

2017-04-26

Extreme toxicity, corrosiveness, and volatility pose serious challenges for the safe storage and transportation of elemental chlorine and bromine, which play critical roles in the chemical industry. Solid materials capable of forming stable nonvolatile compounds upon reaction with elemental halogens may partially mitigate these challenges by allowing safe halogen release on demand. Here we demonstrate that elemental halogens quantitatively oxidize coordinatively unsaturated Co(II) ions in a robust azolate metal-organic framework (MOF) to produce stable and safe-to-handle Co(III) materials featuring terminal Co(III)-halogen bonds. Thermal treatment of the oxidized MOF causes homolytic cleavage of the Co(III)-halogen bonds, reduction to Co(II), and concomitant release of elemental halogens. The reversible chemical storage and thermal release of elemental halogens occur with no significant losses of structural integrity, as the parent cobaltous MOF retains its crystallinity and porosity even after three oxidation/reduction cycles. These results highlight a material operating via redox mechanism that may find utility in the storage and capture of other noxious and corrosive gases.

Mechanistic studies of copper(I)-catalyzed 1,3-halogen migration.

Science.gov (United States)

Van Hoveln, Ryan; Hudson, Brandi M; Wedler, Henry B; Bates, Desiree M; Le Gros, Gabriel; Tantillo, Dean J; Schomaker, Jennifer M

2015-04-29

An ongoing challenge in modern catalysis is to identify and understand new modes of reactivity promoted by earth-abundant and inexpensive first-row transition metals. Herein, we report a mechanistic study of an unusual copper(I)-catalyzed 1,3-migration of 2-bromostyrenes that reincorporates the bromine activating group into the final product with concomitant borylation of the aryl halide bond. A combination of experimental and computational studies indicated this reaction does not involve any oxidation state changes at copper; rather, migration occurs through a series of formal sigmatropic shifts. Insight provided from these studies will be used to expand the utility of aryl copper species in synthesis and develop new ligands for enantioselective copper-catalyzed halogenation.

Phase inversion and frequency doubling of reflection high-energy electron diffraction intensity oscillations in the layer-by-layer growth of complex oxides

Science.gov (United States)

Mao, Zhangwen; Guo, Wei; Ji, Dianxiang; Zhang, Tianwei; Gu, Chenyi; Tang, Chao; Gu, Zhengbin; Nie*, Yuefeng; Pan, Xiaoqing

In situ reflection high-energy electron diffraction (RHEED) and its intensity oscillations are extremely important for the growth of epitaxial thin films with atomic precision. The RHEED intensity oscillations of complex oxides are, however, rather complicated and a general model is still lacking. Here, we report the unusual phase inversion and frequency doubling of RHEED intensity oscillations observed in the layer-by-layer growth of SrTiO3 using oxide molecular beam epitaxy. In contacts to the common understanding that the maximum(minimum) intensity occurs at SrO(TiO2) termination, respectively, we found that both maximum or minimum intensities can occur at SrO, TiO2, or even incomplete terminations depending on the incident angle of the electron beam, which raises a fundamental question if one can rely on the RHEED intensity oscillations to precisely control the growth of thin films. A general model including surface roughness and termination dependent mean inner potential qualitatively explains the observed phenomena, and provides the answer to the question how to prepare atomically and chemically precise surface/interfaces using RHEED oscillations for complex oxides. We thank National Basic Research Program of China (No. 11574135, 2015CB654901) and the National Thousand-Young-Talents Program.

Modification of potentially lethal damage in irradiated Chinese hamster V79 cells after incorporation of halogenated pyrimidines

NARCIS (Netherlands)

Franken, N. A.; van Bree, C. V.; Kipp, J. B.; Barendsen, G. W.

1997-01-01

Radiosensitization of exponentially growing and plateau phase Chinese hamster V79 cells by incorporation of halogenated pyrimidines (HP) was investigated for different culture conditions that influenced repair. For this purpose cells were grown for 72 h with 0, 1, 2 and 4 microM of chloro-(CldUrd),

Development and application of compact denuder sampling techniques with in situ derivatization followed by gas chromatography-mass spectrometry for halogen speciation in volcanic plumes

Science.gov (United States)

Rüdiger, Julian; Bobrowski, Nicole; Hoffmann, Thorsten

2015-04-01

Volcanoes are a large source for several reactive atmospheric trace gases including sulphur and halogen containing species. The detailed knowledge of volcanic plume chemistry can give insights into subsurface processes and can be considered as a useful geochemical tool for monitoring of volcanic activity, especially halogen to sulphur ratios (e.g. Bobrowski and Giuffrida, 2012; Donovan et al., 2014). The reactive bromine species bromine monoxide (BrO) is of particular interest, because BrO as well as SO2 are readily measurable by UV spectrometers at a safe distance. Furthermore it is formed in the plume by a multiphase reaction mechanism under depletion of ozone in the plume. The abundance of BrO changes as a function of the reaction time and therefore distance from the vent as well as the spatial position in the plume. Due to the lack of analytical approaches for the accurate speciation of certain halogens (HBr, Br2, Br, BrCl, HOBr etc.) there are still uncertainties about the magnitude of volcanic halogen emissions and in particular their specificationtheir species and therefore also in the understanding of the bromine chemistry in volcanic plumes (Bobrowski et al., 2007). In this study, the first application of a 1,3,5-trimethoxybenzene (1,3,5-TMB)-coated gas diffusion denuder (Huang and Hoffmann, 2008) on volcanic gases proved to be suitable to collect selectively gaseous bromine species with oxidation states of +1 or 0 (Br2 and BrO(H)), while being ignorant to HBr (OS -1). The reaction of 1,3,5-TMB with bromine gives 1-bromo-2,4,6-trimethoxybenzene (1-bromo-2,4,6-TMB) - other halogens give corresponding products. The diffusion denuder technique allows sampling of gaseous compounds exclusively without collecting particulate matter. Choosing a flow rate of 500 mL-min-1 and a denuder length of 0.5 m a nearly quantitative collection efficiency was achieved. Solvent elution of the derivatized analytes and subsequent analysis with gas chromatography

Improvements in DC Current-Ioltage (I-V) Characteristics of n-GaN Schottky Diode using Metal Overlap Edge Termination

International Nuclear Information System (INIS)

Munir, T.; Aziz, A. A.; Abdullah, M. J.; Ain, M. F.

2010-01-01

Practical design of GaN Schottky diodes incorporating a field plate necessitates an understanding of how the addition of such plate affects the diode performance. In this paper, we investigated the effects on DC current-voltage (I-V) characteristics of n-GaN schottky diode by incorporating metal overlap edge termination. The thickness of the oxide film varies from 0.001 to 1 micron. Two-dimensional Atlas/Blaze simulations revealed that severe electric field crowding across the metal semiconductor contact will cause reliability concern and limit device breakdown voltage. DC current-voltage (I-V) measurements indicate that the forward currents are higher for thinner oxide film schottky diodes with metal overlap edge termination than those of unterminated schottky diodes. The forward current increased due to formation of an accumulation layer underneath the oxide layer. Extending the field plate to beyond periphery regions of schottky contact does not result in any significant increase in forward current. The new techniques of ramp oxide metal overlap edge termination have been implemented to increase the forward current of n-GaN schottky diode. In reverse bias, breakdown voltage increased with edge termination oxide up to a certain limit of oxide thickness.

Layer-by-layer assembly of graphene oxide on polypropylene macroporous membranes via click chemistry to improve antibacterial and antifouling performance

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhen-Bei, E-mail: 1021453457@qq.com [The Key Laboratory of Functional Molecular Solids, Ministry of Education, Anhui Key Laboratory of Molecular-Based Materials, College of Chemistry and Materials Science, Anhui Normal University, East Beijing Rd. 1, Wuhu, Anhui 241000 (China); Wu, Jing-Jing, E-mail: 957522275@qq.com [The Key Laboratory of Functional Molecular Solids, Ministry of Education, Anhui Key Laboratory of Molecular-Based Materials, College of Chemistry and Materials Science, Anhui Normal University, East Beijing Rd. 1, Wuhu, Anhui 241000 (China); Su, Yu, E-mail: 819388710@qq.com [The Key Laboratory of Functional Molecular Solids, Ministry of Education, Anhui Key Laboratory of Molecular-Based Materials, College of Chemistry and Materials Science, Anhui Normal University, East Beijing Rd. 1, Wuhu, Anhui 241000 (China); Zhou, Jin, E-mail: zhoujin_ah@163.com [Department of Materials and Chemical Engineering, Chizhou University, Muzhi Rd. 199, Chizhou, Anhui 247000 (China); Gao, Yong, E-mail: 154682180@qq.com [School of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001 (China); Yu, Hai-Yin, E-mail: yhy456@mail.ahnu.edu.cn [The Key Laboratory of Functional Molecular Solids, Ministry of Education, Anhui Key Laboratory of Molecular-Based Materials, College of Chemistry and Materials Science, Anhui Normal University, East Beijing Rd. 1, Wuhu, Anhui 241000 (China); Gu, Jia-Shan, E-mail: jiashanG@mail.ahnu.edu.cn [The Key Laboratory of Functional Molecular Solids, Ministry of Education, Anhui Key Laboratory of Molecular-Based Materials, College of Chemistry and Materials Science, Anhui Normal University, East Beijing Rd. 1, Wuhu, Anhui 241000 (China)

2015-03-30

Graphical abstract: - Highlights: • Clickable membrane prepared by photo bromination and S{sub N}2 nucleophilic substitution. • Azide graphene oxide prepared by ring-opening reaction. • Alkyne graphene oxide was prepared via esterification reaction. • Layer-by-layer assembly of graphene oxide on membrane by click chemistry. • Antibacterial and antifouling characteristics were enhanced greatly. - Abstract: Polypropylene is an extensively used membrane material; yet, polypropylene membranes exhibit extremely poor resistance to protein fouling. To ameliorate this issue, graphene oxide (GO) nanosheets were used to modify macroporous polypropylene membrane (MPPM) via layer-by-layer assembly technique through click reaction. First, alkyne-terminated GO was prepared through esterification between carboxyl groups in GO and amide groups in propargylamine; azide-terminated GO was synthesized by the ring-opening reaction of epoxy groups in GO with sodium azide. Second, GO was introduced to the membrane by click chemistry. Characterizations of infrared spectra and X-ray photoelectron spectroscopy confirmed the modification. The sharply decreasing of static water contact angle indicated the improvement of the surface hydrophilicity for GO modified membrane. Introducing GO to the membrane results in a dramatic increase of water flux, improvements in the antifouling characteristics and antibacterial property for the membranes. The pure water flux through the 5-layered GO modified membrane is 1.82 times that through the unmodified one. The water flux restores to 43.0% for the unmodified membrane while to 79.8% for the modified membrane. The relative flux reduction decreases by 32.1% due to GO modification. The antibacterial property was also enhanced by two-thirds. These results demonstrate that the antifouling and antibacterial characteristics can be raised by tethering GO to the membrane surface.

Layer-by-layer assembly of graphene oxide on polypropylene macroporous membranes via click chemistry to improve antibacterial and antifouling performance

International Nuclear Information System (INIS)

Zhang, Zhen-Bei; Wu, Jing-Jing; Su, Yu; Zhou, Jin; Gao, Yong; Yu, Hai-Yin; Gu, Jia-Shan

2015-01-01

Graphical abstract: - Highlights: • Clickable membrane prepared by photo bromination and S N 2 nucleophilic substitution. • Azide graphene oxide prepared by ring-opening reaction. • Alkyne graphene oxide was prepared via esterification reaction. • Layer-by-layer assembly of graphene oxide on membrane by click chemistry. • Antibacterial and antifouling characteristics were enhanced greatly. - Abstract: Polypropylene is an extensively used membrane material; yet, polypropylene membranes exhibit extremely poor resistance to protein fouling. To ameliorate this issue, graphene oxide (GO) nanosheets were used to modify macroporous polypropylene membrane (MPPM) via layer-by-layer assembly technique through click reaction. First, alkyne-terminated GO was prepared through esterification between carboxyl groups in GO and amide groups in propargylamine; azide-terminated GO was synthesized by the ring-opening reaction of epoxy groups in GO with sodium azide. Second, GO was introduced to the membrane by click chemistry. Characterizations of infrared spectra and X-ray photoelectron spectroscopy confirmed the modification. The sharply decreasing of static water contact angle indicated the improvement of the surface hydrophilicity for GO modified membrane. Introducing GO to the membrane results in a dramatic increase of water flux, improvements in the antifouling characteristics and antibacterial property for the membranes. The pure water flux through the 5-layered GO modified membrane is 1.82 times that through the unmodified one. The water flux restores to 43.0% for the unmodified membrane while to 79.8% for the modified membrane. The relative flux reduction decreases by 32.1% due to GO modification. The antibacterial property was also enhanced by two-thirds. These results demonstrate that the antifouling and antibacterial characteristics can be raised by tethering GO to the membrane surface

Modified energetics and growth kinetics on H-terminated GaAs (110)

International Nuclear Information System (INIS)

Galiana, B.; Benedicto, M.; Díez-Merino, L.; Tejedor, P.; Lorbek, S.; Hlawacek, G.; Teichert, C.

2013-01-01

Atomic hydrogen modification of the surface energy of GaAs (110) epilayers, grown at high temperatures from molecular beams of Ga and As 4 , has been investigated by friction force microscopy (FFM). The reduction of the friction force observed with longer exposures to the H beam has been correlated with the lowering of the surface energy originated by the progressive de-relaxation of the GaAs (110) surface occurring upon H chemisorption. Our results indicate that the H-terminated GaAs (110) epilayers are more stable than the As-stabilized ones, with the minimum surface energy value of 31 meV/Å 2 measured for the fully hydrogenated surface. A significant reduction of the Ga diffusion length on the H-terminated surface irrespective of H coverage has been calculated from the FFM data, consistent with the layer-by-layer growth mode and the greater As incorporation coefficient determined from real-time reflection high-energy electron diffraction studies. Arsenic incorporation through direct dissociative chemisorption of single As 4 molecules mediated by H on the GaAs (110) surface has been proposed as the most likely explanation for the changes in surface kinetics observed

Modified energetics and growth kinetics on H-terminated GaAs (110)

Energy Technology Data Exchange (ETDEWEB)

Galiana, B. [Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, 28049 Madrid (Spain); Departamento de Física, Universidad Carlos III de Madrid, Avenida de la Universidad 30, 28911 Madrid (Spain); Benedicto, M.; Díez-Merino, L.; Tejedor, P. [Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, 28049 Madrid (Spain); Lorbek, S.; Hlawacek, G.; Teichert, C. [Institut für Physik, Montanuniversität Leoben, Franz Josef St., 18A-8700 Leoben (Austria)

2013-10-28

Atomic hydrogen modification of the surface energy of GaAs (110) epilayers, grown at high temperatures from molecular beams of Ga and As{sub 4}, has been investigated by friction force microscopy (FFM). The reduction of the friction force observed with longer exposures to the H beam has been correlated with the lowering of the surface energy originated by the progressive de-relaxation of the GaAs (110) surface occurring upon H chemisorption. Our results indicate that the H-terminated GaAs (110) epilayers are more stable than the As-stabilized ones, with the minimum surface energy value of 31 meV/Å{sup 2} measured for the fully hydrogenated surface. A significant reduction of the Ga diffusion length on the H-terminated surface irrespective of H coverage has been calculated from the FFM data, consistent with the layer-by-layer growth mode and the greater As incorporation coefficient determined from real-time reflection high-energy electron diffraction studies. Arsenic incorporation through direct dissociative chemisorption of single As{sub 4} molecules mediated by H on the GaAs (110) surface has been proposed as the most likely explanation for the changes in surface kinetics observed.

Surface Modification of Titanium with Heparin-Chitosan Multilayers via Layer-by-Layer Self-Assembly Technique

International Nuclear Information System (INIS)

Shu, Y.; Zou, J.; Ou, G.; Wang, L.; Li, Q.

2011-01-01

Extracellular matrix (ECM), like biomimetic surface modification of titanium implants, is a promising method for improving its biocompatibility. In this paper chitosan (Chi) and heparin (Hep) multilayer was coated on pure titanium using a layer-by-layer (LbL) self-assembly technique. The Hep-Chi multilayer growth was carried out by first depositing a single layer of positively charged poly-L-lysine (PLL) on the NaOH-treated titanium substrate (negatively charged surface), followed by alternate deposition of negatively charged Hep and positively charged Chi, and terminated by an outermost layer of Chi. The multilayer was characterized by DR-FTIR, SEM, and AFM, and osteoblasts were cocultured with the modified titanium and untreated titanium surfaces, respectively, to evaluate their cytocompatibility in vitro. The results confirmed that Hep-Chi multilayer was fabricated gradually on the titanium surface. The Hep-Chi multilayer-coated titanium improved the adhesion, proliferation and differentiation of osteoblasts. Thus, the approach described here may provide a basis for the preparation of modified titanium surfaces for use in dental or orthopedic implants

Recent trends in the variability of halogenated trace gases over the United States

Science.gov (United States)

Hurst, Dale F.; Bakwin, Peter S.; Elkins, James W.

1998-10-01

Recent trends in the atmospheric variability of seven halogenated trace gases are determined from three years (November 1994 through October 1997) of hourly gas chromatographic measurements at a 610 m tower in North Carolina and 17 months (June 1996 through October 1997) of similar measurements at a 450 m tower in Wisconsin. Production of five of these gases, CCl3F (CFC-11), CCl2F2 (CFC-12), CCl2FCClF2 (CFC-113), CH3CCl3 (methyl chloroform), and CCl4 (carbon tetrachloride), is now strictly regulated in the United States and other developed countries under international legislation. C2Cl4 (tetrachloroethene) and SF6 (sulfur hexafluoride) are currently produced without restriction, but requests for voluntary cutbacks in C2Cl4 emissions have been made, at least in the United States. Atmospheric variability of these gases is examined at several sampling heights on the towers, but trends are deduced using only nighttime data at the top sampling level of each tower to minimize variability driven by local emissions and the diurnal cycle of the planetary boundary layer, leaving regional emissions as the main source of day-to-day variability. Significant downward trends are determined for CFC-12, CFC-113, CH3CCl3, and C2Cl4 variability at both towers, reflecting decreased emissions of these gases in two regions of the United States. Trends in CFC-11, CCl4, and SF6 variability at both towers are not significantly different from zero.

Influence of halogen irradiance on short- and long-term wear resistance of resin-based composite materials.

LENUS (Irish Health Repository)

Bhamra, Gurcharn S

2009-02-01

The Oregon Health Science University (OHSU) four-chamber oral wear simulator was used to examine the impact of halogen irradiance on the short- and long-term wear behavior of four-methacrylate resin-based composites (RBCs). The hypothesis proposed was that exacerbated wear would occur following the long-term wear of RBCs irradiated under non-optimized irradiance conditions.

Electro-responsivity of ionic liquid boundary layers in a polar solvent revealed by neutron reflectance

Science.gov (United States)

Pilkington, Georgia A.; Harris, Kathryn; Bergendal, Erik; Reddy, Akepati Bhaskar; Palsson, Gunnar K.; Vorobiev, Alexei; Antzutkin, Oleg. N.; Glavatskih, Sergei; Rutland, Mark W.

2018-05-01

Using neutron reflectivity, the electro-responsive structuring of the non-halogenated ionic liquid (IL) trihexyl(tetradecyl)phosphonium-bis(mandelato)borate, [P6,6,6,14][BMB], has been studied at a gold electrode surface in a polar solvent. For a 20% w/w IL mixture, contrast matched to the gold surface, distinct Kiessig fringes were observed for all potentials studied, indicative of a boundary layer of different composition to that of the bulk IL-solvent mixture. With applied potential, the amplitudes of the fringes from the gold-boundary layer interface varied systematically. These changes are attributable to the differing ratios of cations and anions in the boundary layer, leading to a greater or diminished contrast with the gold electrode, depending on the individual ion scattering length densities. Such electro-responsive changes were also evident in the reflectivities measured for the pure IL and a less concentrated (5% w/w) IL-solvent mixture at the same applied potentials, but gave rise to less pronounced changes. These measurements, therefore, demonstrate the enhanced sensitivity achieved by contrast matching the bulk solution and that the structure of the IL boundary layers formed in mixtures is strongly influenced by the bulk concentration. Together these results represent an important step in characterising IL boundary layers in IL-solvent mixtures and provide clear evidence of electro-responsive structuring of IL ions in their solutions with applied potential.

Possibilities of analyzing dump and sewage gas, and determination of halogen and sulfur compounds

Energy Technology Data Exchange (ETDEWEB)

Eisenmann, R

1985-01-01

In connection with the utilization of refuse and sewage gas efficacions analytical methods are gaining increasing importance especially with regard to halogen and sulfur compounds. The paper describes various possibilities to determine those substances. Besides gas chromatography it takes into account classic analytical methods which can be superior in biogas analytics to modern physical processes. The advantages and disadvantages of each method are discussed and practical experiences obtained by their application reported.

The gas-chromatographic and gas-chromatographic-mass-spectrometric identification of halogen-containing organic compounds

Science.gov (United States)

Gidaspov, B. V.; Zenkevich, I. G.; Rodin, A. A.

1989-09-01

The problem of identifying halogen-containing organic compounds in their gas-chromatographic and gas-chromatographic-mass-spectrometric (GC-MS) determination in different materials has been examined. Particular attention has been paid not to the complete characterisation of methods for carrying out this analysis but to the most important problem of increasing the selectivity at the stages of sampling, separation, and interpretation of the gas-chromatographic and GC-MS information. The bibliography contains 292 references.

Effect of halogenated benzenes on acetanilide esterase, acetanilide hydroxylase and procaine esterase in rats.

Science.gov (United States)

Carlson, G P; Dziezak, J D; Johnson, K M

1979-07-01

1,2,4-Trichlorobenzene, 1,3,5-trichlorobenzene, hexachlorobenzene, 1,2,4-tribromobenzene, 1,3,5-tribromobenzene and hexabromobenzene were compared for their abilities to induce acetanilide esterase, acentailide hydroxylase and procaine esterase. Except for hexabromobenzene all induced acetanilide esterase whereas the hydroxylation of acetanilide was seen only with the fully halogenated benzenes and with 1,3,5-tribromobenzene. Hepatic procaine esterase activity was increased by the three chlorinated benzenes and 1,2,4-tribromobenzene.

On Extension of the Current Biomolecular Empirical Force Field for the Description of Halogen Bonds

Czech Academy of Sciences Publication Activity Database

Kolář, Michal; Hobza, Pavel

2012-01-01

Roč. 8, č. 4 (2012), s. 1325-1333 ISSN 1549-9618 R&D Projects: GA ČR GBP208/12/G016 Grant - others:European Science Fund(XE) CZ.1.05/2.1.00/03.0058 Institutional research plan: CEZ:AV0Z40550506 Keywords : halogen bond * molecular mechanics * sigma-hole Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.389, year: 2012

Biomimetic PDMS-hydroxyurethane terminated with catecholic moieties for chemical grafting on transition metal oxide-based surfaces

Science.gov (United States)

de Aguiar, Kelen R.; Rischka, Klaus; Gätjen, Linda; Noeske, Paul-Ludwig Michael; Cavalcanti, Welchy Leite; Rodrigues-Filho, Ubirajara P.

2018-01-01

The aim of this work was to synthesize a non-isocyanate poly(dimethylsiloxane) hydroxyurethane with biomimetic terminal catechol moieties, as a candidate for inorganic and metallic surface modification. Such surface modifier is capable to strongly attach onto metallic and inorganic substrates forming layers and, in addition, providing water-repellent surfaces. The non-isocyanate route is based on carbon dioxide cycloaddition into bis-epoxide, resulting in a precursor bis(cyclic carbonate)-polydimethylsiloxane (CCPDMS), thus fully replacing isocyanate in the manufacture process. A biomimetic approach was chosen with the molecular composition being inspired by terminal peptides present in adhesive proteins of mussels, like Mefp (Mytilus edulis foot protein), which bear catechol moieties and are strong adhesives even under natural and saline water. The catechol terminal groups were grafted by aminolysis reaction into a polydimethylsiloxane backbone. The product, PDMSUr-Dopamine, presented high affinity towards inhomogeneous alloy surfaces terminated by native oxide layers as demonstrated by quartz crystal microbalance (QCM-D), as well as stability against desorption by rinsing with ethanol. As revealed by QCM-D, X-ray photoelectron spectroscopy (XPS) and computational studies, the thickness and composition of the resulting nanolayers indicated an attachment of PDMSUr-Dopamine molecules to the substrate through both terminal catechol groups, with the adsorbate exposing the hydrophobic PDMS backbone. This hypothesis was investigated by classical molecular dynamic simulation (MD) of pure PDMSUr-Dopamine molecules on SiO2 surfaces. The computationally obtained PDMSUr-Dopamine assembly is in agreement with the conclusions from the experiments regarding the conformation of PDMSUr-Dopamine towards the surface. The tendency of the terminal catechol groups to approach the surface is in agreement with proposed model for the attachment PDMSUr-Dopamine. Remarkably, the versatile

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.

The influence of microplastics and halogenated contaminants in feed on toxicokinetics and gene expression in European seabass (Dicentrarchus labrax)

NARCIS (Netherlands)

Granby, Kit; Rainieri, Sandra; Rasmussen, Rie Romme; Kotterman, Michiel J.J.; Sloth, Jens Jørgen; Cederberg, Tommy Licht; Barranco, Alex; Marques, António; Larsen, Bodil Katrine

2018-01-01

When microplastics pollute fish habitats, it may be ingested by fish, thereby contaminating fish with sorbed contaminants. The present study investigates how combinations of halogenated contaminants and microplastics associated with feed are able to alter toxicokinetics in European seabass and

Synthesis and physical and chemical properties of poly-hydro-aluminates and poly-halogen-aluminates metals of II A group

International Nuclear Information System (INIS)

Khudoydodov, B.O.

1990-01-01

The purpose of the present work is investigation of conditions and mechanism of passing of formation reactions of aluminum hydrides, poly-hydride-aluminates and poly-halogen-aluminates of alkaline-earth metals and magnesium and studying of their physical and chemical properties

Osteogenic cell differentiation on H-terminated and O-terminated nanocrystalline diamond films

Directory of Open Access Journals (Sweden)

Liskova J

2015-01-01

Full Text Available Jana Liskova,1 Oleg Babchenko,2 Marian Varga,2 Alexander Kromka,2 Daniel Hadraba,1 Zdenek Svindrych,1 Zuzana Burdikova,1 Lucie Bacakova1 1Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic; 2Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic Abstract: Nanocrystalline diamond (NCD films are promising materials for bone implant coatings because of their biocompatibility, chemical resistance, and mechanical hardness. Moreover, NCD wettability can be tailored by grafting specific atoms. The NCD films used in this study were grown on silicon substrates by microwave plasma-enhanced chemical vapor deposition and grafted by hydrogen atoms (H-termination or oxygen atoms (O-termination. Human osteoblast-like Saos-2 cells were used for biological studies on H-terminated and O-terminated NCD films. The adhesion, growth, and subsequent differentiation of the osteoblasts on NCD films were examined, and the extracellular matrix production and composition were quantified. The osteoblasts that had been cultivated on the O-terminated NCD films exhibited a higher growth rate than those grown on the H-terminated NCD films. The mature collagen fibers were detected in Saos-2 cells on both the H-terminated and O-terminated NCD films; however, the quantity of total collagen in the extracellular matrix was higher on the O-terminated NCD films, as were the amounts of calcium deposition and alkaline phosphatase activity. Nevertheless, the expression of genes for osteogenic markers – type I collagen, alkaline phosphatase, and osteocalcin – was either comparable on the H-terminated and O-terminated films or even lower on the O-terminated films. In conclusion, the higher wettability of the O-terminated NCD films is promising for adhesion and growth of osteoblasts. In addition, the O-terminated surface also seems to support the deposition of extracellular matrix proteins and extracellular matrix

N-Oxide-N-oxide interactions and Cl...Cl halogen bonds in pentachloropyridine N-oxide: the many-body approach to interactions in the crystal state.

Science.gov (United States)

Wzgarda-Raj, Kinga; Rybarczyk-Pirek, Agnieszka J; Wojtulewski, Sławomir; Palusiak, Marcin

2018-02-01

Pentachloropyridine N-oxide, C 5 Cl 5 NO, crystallizes in the monoclinic space group P2 1 /c. In the crystal structure, molecules are linked by C-Cl...Cl halogen bonds into infinite ribbons extending along the crystallographic [100] direction. These molecular aggregates are further stabilized by very short intermolecular N-oxide-N-oxide interactions into herringbone motifs. Computations based on quantum chemistry methods allowed for a more detailed description of the N-oxide-N-oxide interactions and Cl...Cl halogen bonds. For this purpose, Hirshfeld surface analysis and the many-body approach to interaction energy were applied.

Organizational Relationship Termination Competence

DEFF Research Database (Denmark)

Ritter, Thomas; Geersbro, Jens

2011-01-01

termination are found to significantly affect a firm's relationship termination competence. The findings suggest that managers should regard termination as a legitimate option in customer relationship management. In order to decrease the number of unwanted customers, managers must accept termination......Most firms are involved in a number of customer relationships that drain the firm's resources. However, many firms are hesitant to address this problem. This paper investigates customer relationship termination at the organizational level. We develop and analyze the organizational dimensions...... of organizational termination in order to improve our understanding of the management of termination. The impact of these termination dimensions on the percentage of unwanted customers is developed and tested using PLS on data gathered from a cross-sectional survey of more than 800 sales representatives. We find...

Fluorescence cell imaging and manipulation using conventional halogen lamp microscopy.

Directory of Open Access Journals (Sweden)

Kazuo Yamagata

Full Text Available Technologies for vitally labeling cells with fluorescent dyes have advanced remarkably. However, to excite fluorescent dyes currently requires powerful illumination, which can cause phototoxic damage to the cells and increases the cost of microscopy. We have developed a filter system to excite fluorescent dyes using a conventional transmission microscope equipped with a halogen lamp. This method allows us to observe previously invisible cell organelles, such as the metaphase spindle of oocytes, without causing phototoxicity. Cells remain healthy even after intensive manipulation under fluorescence observation, such as during bovine, porcine and mouse somatic cell cloning using nuclear transfer. This method does not require expensive epifluorescence equipment and so could help to reduce the science gap between developed and developing countries.

Permuting the PGF Signature Motif Blocks both Archaeosortase-Dependent C-Terminal Cleavage and Prenyl Lipid Attachment for the Haloferax volcanii S-Layer Glycoprotein.

Science.gov (United States)

Abdul Halim, Mohd Farid; Karch, Kelly R; Zhou, Yitian; Haft, Daniel H; Garcia, Benjamin A; Pohlschroder, Mechthild

2015-12-28

For years, the S-layer glycoprotein (SLG), the sole component of many archaeal cell walls, was thought to be anchored to the cell surface by a C-terminal transmembrane segment. Recently, however, we demonstrated that the Haloferax volcanii SLG C terminus is removed by an archaeosortase (ArtA), a novel peptidase. SLG, which was previously shown to be lipid modified, contains a C-terminal tripartite structure, including a highly conserved proline-glycine-phenylalanine (PGF) motif. Here, we demonstrate that ArtA does not process an SLG variant where the PGF motif is replaced with a PFG motif (slg(G796F,F797G)). Furthermore, using radiolabeling, we show that SLG lipid modification requires the PGF motif and is ArtA dependent, lending confirmation to the use of a novel C-terminal lipid-mediated protein-anchoring mechanism by prokaryotes. Similar to the case for the ΔartA strain, the growth, cellular morphology, and cell wall of the slg(G796F,F797G) strain, in which modifications of additional H. volcanii ArtA substrates should not be altered, are adversely affected, demonstrating the importance of these posttranslational SLG modifications. Our data suggest that ArtA is either directly or indirectly involved in a novel proteolysis-coupled, covalent lipid-mediated anchoring mechanism. Given that archaeosortase homologs are encoded by a broad range of prokaryotes, it is likely that this anchoring mechanism is widely conserved. Prokaryotic proteins bound to cell surfaces through intercalation, covalent attachment, or protein-protein interactions play critical roles in essential cellular processes. Unfortunately, the molecular mechanisms that anchor proteins to archaeal cell surfaces remain poorly characterized. Here, using the archaeon H. volcanii as a model system, we report the first in vivo studies of a novel protein-anchoring pathway involving lipid modification of a peptidase-processed C terminus. Our findings not only yield important insights into poorly understood

Kitimat LNG terminal

International Nuclear Information System (INIS)

Schmaltz, I.; Boulton, R.

2007-01-01

Kitimat Liquefied Natural Gas (LNG) terminal is a terminal development company owned by Galveston LNG, a privately owned Canadian energy development company. This presentation provided information on Kitimat LNG with particular reference to its terminal located in Bish Cove on the Douglas Channel in British Columbia. This LNG terminal is reported to be the only fully permitted regasification terminal on the west coast of Canada and the United States. The presentation addressed market fundamentals including several graphs, such as world natural gas proved reserves in 2006; LNG supplements to Canadian gas supplies; global LNG demand for 2005-2020; average annual United States LNG imports; and global LNG liquefaction projects. Other market fundamentals were described, including that Kitimat is the only other approved terminal aside from the Costa Azul terminal in Mexico; Kitimat is the only west coast LNG import terminal that connects to midwest and eastern North American markets through existing gas pipelines; LNG producers are looking for destination diversification; and markets and marketers are looking for supply diversification. The authors noted that by 2010, western Canadian gas demand will exceed Californian demand. Other topics that were discussed in the presentation included Canadian natural gas field receipts; unadjusted bitumen production outlook; oil sands gas demand; forward basis fundamentals; and the commercial drivers of the Kitimat LNG terminal. The presentation also discussed the pacific trail pipelines, a partnership between Galveston LNG and Pacific Northern Gas to develop the natural gas transmission line from Kitimat to Summit. The presentation concluded with a discussion of the benefits of Kitimat LNG terminal such as providing access to the largest natural gas markets in the world via major gas transmission lines with spare capacity. figs

Identifying bioaccumulative halogenated organic compounds using a nontargeted analytical approach: seabirds as sentinels.

Directory of Open Access Journals (Sweden)

Christopher J Millow

Full Text Available Persistent organic pollutants (POPs are typically monitored via targeted mass spectrometry, which potentially identifies only a fraction of the contaminants actually present in environmental samples. With new anthropogenic compounds continuously introduced to the environment, novel and proactive approaches that provide a comprehensive alternative to targeted methods are needed in order to more completely characterize the diversity of known and unknown compounds likely to cause adverse effects. Nontargeted mass spectrometry attempts to extensively screen for compounds, providing a feasible approach for identifying contaminants that warrant future monitoring. We employed a nontargeted analytical method using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS to characterize halogenated organic compounds (HOCs in California Black skimmer (Rynchops niger eggs. Our study identified 111 HOCs; 84 of these compounds were regularly detected via targeted approaches, while 27 were classified as typically unmonitored or unknown. Typically unmonitored compounds of note in bird eggs included tris(4-chlorophenylmethane (TCPM, tris(4-chlorophenylmethanol (TCPMOH, triclosan, permethrin, heptachloro-1'-methyl-1,2'-bipyrrole (MBP, as well as four halogenated unknown compounds that could not be identified through database searching or the literature. The presence of these compounds in Black skimmer eggs suggests they are persistent, bioaccumulative, potentially biomagnifying, and maternally transferring. Our results highlight the utility and importance of employing nontargeted analytical tools to assess true contaminant burdens in organisms, as well as to demonstrate the value in using environmental sentinels to proactively identify novel contaminants.

Small-Molecule Organic Photovoltaic Modules Fabricated via Halogen-Free Solvent System with Roll-to-Roll Compatible Scalable Printing Method.

Science.gov (United States)

Heo, Youn-Jung; Jung, Yen-Sook; Hwang, Kyeongil; Kim, Jueng-Eun; Yeo, Jun-Seok; Lee, Sehyun; Jeon, Ye-Jin; Lee, Donmin; Kim, Dong-Yu

2017-11-15

For the first time, the photovoltaic modules composed of small molecule were successfully fabricated by using roll-to-roll compatible printing techniques. In this study, blend films of small molecules, BTR and PC 71 BM were slot-die coated using a halogen-free solvent system. As a result, high efficiencies of 7.46% and 6.56% were achieved from time-consuming solvent vapor annealing (SVA) treatment and roll-to-roll compatible solvent additive approaches, respectively. After successful verification of our roll-to-roll compatible method on small-area devices, we further fabricated large-area photovoltaic modules with a total active area of 10 cm 2 , achieving a power conversion efficiency (PCE) of 4.83%. This demonstration of large-area photovoltaic modules through roll-to-roll compatible printing methods, even based on a halogen-free solvent, suggests the great potential for the industrial-scale production of organic solar cells (OSCs).

Application of nanomaterials in two-terminal resistive-switching memory devices

Directory of Open Access Journals (Sweden)

Jianyong Ouyang

2010-05-01

Full Text Available Nanometer materials have been attracting strong attention due to their interesting structure and properties. Many important practical applications have been demonstrated for nanometer materials based on their unique properties. This article provides a review on the fabrication, electrical characterization, and memory application of two-terminal resistive-switching devices using nanomaterials as the active components, including metal and semiconductor nanoparticles (NPs, nanotubes, nanowires, and graphenes. There are mainly two types of device architectures for the two-terminal devices with NPs. One has a triple-layer structure with a metal film sandwiched between two organic semiconductor layers, and the other has a single polymer film blended with NPs. These devices can be electrically switched between two states with significant different resistances, i.e. the ‘ON’ and ‘OFF’ states. These render the devices important application as two-terminal non-volatile memory devices. The electrical behavior of these devices can be affected by the materials in the active layer and the electrodes. Though the mechanism for the electrical switches has been in argument, it is generally believed that the resistive switches are related to charge storage on the NPs. Resistive switches were also observed on crossbars formed by nanotubes, nanowires, and graphene ribbons. The resistive switches are due to nanoelectromechanical behavior of the materials. The Coulombic interaction of transient charges on the nanomaterials affects the configurable gap of the crossbars, which results into significant change in current through the crossbars. These nanoelectromechanical devices can be used as fast-response and high-density memory devices as well. Dr. Jianyong Ouyang received his bachelor degree from the Tsinghua University in Beijing, China, and MSc from the Institute of Chemistry, Chinese Academy of Science. He received his PhD from the Institute for Molecular

Could the increased structural versatility imposed by non-halogen ligands bring something new for polynuclear superhalogens? A case study on binuclear [Mg2L5]- (L = -OH, -OOH and -OF) anions.

Science.gov (United States)

Zhao, Ru-Fang; Yu, Le; Zhou, Fu-Qiang; Li, Jin-Feng; Yin, Bing

2017-10-11

A combined ab initio and DFT study is performed in this work to explore the superhalogen properties of polynuclear structures based on the ligands of -OH, -OOH and -OF. According to high-level CCSD(T) results, all the structures here are superhalogens whose properties are superior to the corresponding mononuclear ones. Although inferior to similar structures based on F ligands, some of the superhalogens here are capable of transcending the traditional ones based on Cl atoms. Therefore the superhalogen properties of the anions here are still promising and they have an important advantage of high safety, which is crucial for practical applications. An increased degree of structural versatility is imposed by these non-halogen ligands because of the various ways in which they connect the central atoms and their multiple orientations. It is important that this increased versatility will bring new factors, e.g., the larger spatial extent of the whole cluster and the existence of intra-molecular hydrogen bonds, which should favour high VDE values. These factors are not available in traditional halogen-based systems and they may play an important role in the future search for novel superhalogens. (HF + MP2)/2, ωB97XD as well as M06-2X are capable of providing accurate VDE values, close to the CCSD(T) results, and their absolute errors are even lower than that of the OVGF. Due to the good balance between the accuracy and efficiency, these methods could provide reliable predictions on large systems which cannot be treated with CCSD(T) or even with the OVGF. Balanced distribution of the extra electron, between the terminal and bridging ligands, is also shown to be favourable to realize a high VDE value.

Halogen species record Antarctic sea ice extent over glacial–interglacial periods

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A. Spolaor

2013-07-01

Full Text Available Sea ice is an integral part of the earth's climate system because it affects planetary albedo, sea-surface salinity, and the atmosphere–ocean exchange of reactive gases and aerosols. Bromine and iodine chemistry is active at polar sea ice margins with the occurrence of bromine explosions and the biological production of organoiodine from sea ice algae. Satellite measurements demonstrate that concentrations of bromine oxide (BrO and iodine oxide (IO decrease over sea ice toward the Antarctic interior. Here we present speciation measurements of bromine and iodine in the TALDICE (TALos Dome Ice CorE ice core (159°11' E, 72°49' S; 2315 m a.s.l. spanning the last 215 ky. The Talos Dome ice core is located 250 km inland and is sensitive to marine air masses intruding onto the Antarctic Plateau. Talos Dome bromide (Br− is positively correlated with temperature and negatively correlated with sodium (Na. Based on the Br−/Na seawater ratio, bromide is depleted in the ice during glacial periods and enriched during interglacial periods. Total iodine, consisting of iodide (I− and iodate (IO3−, peaks during glacials with lower values during interglacial periods. Although IO3− is considered the most stable iodine species in the atmosphere it was only observed in the TALDICE record during glacial maxima. Sea ice dynamics are arguably the primary driver of halogen fluxes over glacial–interglacial timescales, by altering the distance between the sea ice edge and the Antarctic plateau and by altering the surface area of sea ice available to algal colonization. Based on our results we propose the use of both halogens for examining Antarctic variability of past sea ice extent.

Negative ion formation in dissociative electron attachment to selected halogen derivatives of propane

Science.gov (United States)

Barszczewska, W.; Kocísek, J.; Skalný, J.; Matejcík, V.; Matejcík, S.

2008-11-01

Dissociative electron attachment (DEA) to halogenated derivatives of propane: 1-bromo-3-chloropropane, 2-bromo-1-chloropropane, 3-bromo-1,1,1-trichloropropane and 1,3-dibromo-1,1-difluoropropane was studied in the gas phase at ambient temperature using a high resolution crossed electron/molecule beams technique. The negative ions formed via DEA reaction were identified using mass spectrometric technique and the anion yields were measured in the electron energy range from 0 to 10 eV. The absolute partial cross sections for DEA to the molecules were estimated using the relative flow technique.

Spectrally dependent photovoltages in Schottky photodiode based on (100) B-doped diamond

International Nuclear Information System (INIS)

Čermák, Jan; Rezek, Bohuslav; Koide, Yasuo; Takeuchi, Daisuke

2014-01-01

Spectrally and spatially resolved photovoltages were measured by Kelvin probe force microscopy (KPFM) on a Schottky photo-diode made of a 4 nm thin tungsten-carbide (WC) layer on a 500 nm oxygen-terminated boron-doped diamond epitaxial layer (O-BDD) that was grown on a Ib (100) diamond substrate. The diode was grounded by the sideways ohmic contact (Ti/WC), and the semitransparent Schottky contact was let unconnected. The electrical potentials across the device were measured in dark (only 650 nm LED of KPFM being on), under broad-band white light (halogen lamp), UV (365 nm diode), and deep ultraviolet (deuterium lamp) illumination. Illumination induced shift of the electrical potential remains within 210 mV. We propose that the photovoltage actually corresponds to a shift of Fermi level inside the BDD channel and thereby explains orders of magnitude changes in photocurrent

Spectrally dependent photovoltages in Schottky photodiode based on (100) B-doped diamond

Energy Technology Data Exchange (ETDEWEB)

Čermák, Jan, E-mail: cermakj@fzu.cz; Rezek, Bohuslav [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 16200 Prague 6 (Czech Republic); Koide, Yasuo [Sensor Materials Center, National Institute for Material Science (NIMS), 1-1 Namiki, Tsukuba 305-0044 (Japan); Takeuchi, Daisuke [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba 305-8568 (Japan)

2014-02-07

Spectrally and spatially resolved photovoltages were measured by Kelvin probe force microscopy (KPFM) on a Schottky photo-diode made of a 4 nm thin tungsten-carbide (WC) layer on a 500 nm oxygen-terminated boron-doped diamond epitaxial layer (O-BDD) that was grown on a Ib (100) diamond substrate. The diode was grounded by the sideways ohmic contact (Ti/WC), and the semitransparent Schottky contact was let unconnected. The electrical potentials across the device were measured in dark (only 650 nm LED of KPFM being on), under broad-band white light (halogen lamp), UV (365 nm diode), and deep ultraviolet (deuterium lamp) illumination. Illumination induced shift of the electrical potential remains within 210 mV. We propose that the photovoltage actually corresponds to a shift of Fermi level inside the BDD channel and thereby explains orders of magnitude changes in photocurrent.

In vitro comparative study of share bond of light cured composite resins with halogen light and argon laser, using stainless steel brackets on human premolars

International Nuclear Information System (INIS)

Carillo, Vitoria Eugenia Bismarck

2004-01-01

The aim of this study in vitro was to compare the share bond strength of the light-cured composite resins Transbond XT (Unitek), with halogen light and argon laser. The Adhesive Remmant Index (ARI) was also investigated. The brackets Dyna lock (3M-UNITEK) were bonded to 75 human premolars, divided into 5 groups (15 each) according to time and the polymerization: Group H20, 15 brackets bonded with halogen light for 20s (10s both sides); Group H40, 15 brackets bonded with halogen light for 40s (20s both sides); Group A40, 15 brackets bonded with argon laser for 40s (20s both sides); Group A20, 15 brackets bonded with argon laser for 20s (10s both sides); Group A10, 15 brackets bonded with argon laser for 10s (5s both sides). The pulpal temperature changes were determined during a polymerization, not exceeding 3,5 deg C. After bonding, the teeth were submitted to a thermo cycled of 700 cycles between 5 deg C and 55 deg C, to simulate the consuming that the light cured composite resin would have in a short space of time. The specimens were then placed in PVC ring and embedded in acrylic resin (Aero-Jet). The tensile bond strength test was performed on an Universal Machine set at a crosshead speed of 1,5 mm/min, and for each rupture we registered a graphic and the best load required in Newtons, was converted to MPa and kgf. The share bond strength showed bigger values for the exposure time of 20 seconds, for the Group bonded for halogen light (H20), 7,45 kgf (7,64 MPa) and for argon laser 7,50 kgf (7,69 MPa); lesser values for the exposure time of 40s for the Group with halogen light (H40), 6,15 kgf (6,30 MPa) and argon laser Group (A40), 6,20 kgf (6,35 MPa) 0; and A10, 4,85 kgf (4,97 MPa). In the ARI Index, only A40 Group showed the 1 Index, with statistical results. In this Group, less than half of the remainder adhesive stayed on the surface of the enamel, conferring specimens failed at the enamel-adhesive interface. The results of the in vitro study demonstrate that

Experimental study on the 4H-SiC-based VDMOSFETs with lightly doped P-well field-limiting rings termination

Science.gov (United States)

He, Yan Jing; Lv, Hong Liang; Tang, Xiao Yan; Song, Qing Wen; Zhang, Yi Meng; Han, Chao; Zhang, Yi Men; Zhang, Yu Ming

2017-03-01

A lightly doped P-well field-limiting rings (FLRs) termination on 4H-SiC vertical double-implanted metal-oxide-semiconductor field-effect transistors (VDMOSFETs) has been investigated. Based on the simulation, the proposed termination applied to 4H-SiC VDMOSFET could achieve an almost same breakdown voltage (BV) and have the advantage of lower ion-implantation damage comparing with P+ FLRs termination. Meanwhile, this kind of termination also reduces the difficulty and consumption of fabrication process. 4H-SiC VDMOSFETs with lightly doped P-well (FLRs) termination have been fabricated on 10 μm thick epi-layer with nitrogen doping concentration of 6.2 × 1015 cm-3. The maximum breakdown voltage of the 4H-SiC VDMOSFETs has achieved as high as 1610 V at a current of 15 μA, which is very close to the simulated result of 1643 V and about 90% of the plane parallel breakdown voltage of 1780 V. It is considered that P-well FLRs termination is an effective, robust and process-tolerant termination structure suitable for 4H-SiC VDMOSFET.

Digital solar edge tracker for the Halogen Occultation Experiment

Science.gov (United States)

Mauldin, L. E., III; Moore, A. S.; Stump, C. W.; Mayo, L. S.

1987-01-01

The optical and electronic design of the Halogen Occultation Experiment (Haloe) elevation sun sensor is described. The Haloe instrument is a gas-correlation radiometer now being developed at NASA Langley for the Upper Atmosphere Research Satellite. The system uses a Galilean telescope to form a solar image on a linear silicon photodiode array. The array is a self-scanned monolithic CCD. The addresses of both solar edges imaged on the array are used by the control/pointing system to scan the Haloe science instantaneous field of view (IFOV) across the vertical solar diameter during instrument calibration and then to maintain the science IFOV 4 arcmin below the top edge during the science data occultation event. Vertical resolution of 16 arcsec and a radiometric dynamic range of 100 are achieved at the 700-nm operating wavelength. The design provides for loss of individual photodiode elements without loss of angular tracking capability.

5G Terminals with Multi-Streaming Features for Real-Time Mobile Broadband Applications

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T. Shuminoski

2017-06-01

Full Text Available In this paper we present a novel QoS framework on the network layer for 5G terminals with vertical multi-homing and multi-streaming capabilities by using radio networks aggregation. The proposed framework is leading to high performance utility networks with QoS provisioning for real-time multimedia services by achieving low packet delays, stochastic queuing network stability and highest mobile broadband capabilities i.e. bitrates. The proposed QoS algorithm is implemented within the mobile terminals on one side, and in dedicated proxy servers on mobile core network side. It is based on Lyapunov optimization techniques and it is targeted to handle simultaneously multiple multimedia service flows via multiple radio network interfaces in parallel.

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.

Halogen speciation in volcanic plumes - Development of compact denuder sampling techniques with in-situ derivatization followed by gas chromatography-mass spectrometry and their application at Mt. Etna, Mt. Nyiragongo and Mt. Nyamulagira in 2015.

Science.gov (United States)

Rüdiger, Julian; Bobrowski, Nicole; Hoffmann, Thorsten

2016-04-01

Volcanoes are a large source for several reactive atmospheric trace gases including sulfur and halogen containing species. The detailed knowledge of volcanic plume chemistry can give insights into subsurface processes and can be considered as a useful geochemical tool for monitoring of volcanic activity, especially halogen to sulfur ratios (e.g. Bobrowski and Giuffrida, 2012; Donovan et al., 2014). The reactive bromine species bromine monoxide (BrO) is of particular interest, because BrO as well as SO2 are readily measurable by UV spectrometer at a safe distance. Furthermore it is formed in the plume by a multiphase reaction mechanism under depletion of ozone in the plume. The abundance of BrO changes as a function of the reaction time and therefore distance from the vent as well as the spatial position in the plume. The precursor substance for the formation of BrO is HBr with Br2as an intermediate product. The reaction of HBr to BrO involves heterogeneous reactions involving aerosol particles, while Br2 reacts directly with O3 to form BrO in a UV radiation induced mechanism. Due to the lack of analytical approaches for the species analysis of halogens (HBr, Br2, Br, BrCl, HOBr) there are still uncertainties about the magnitude of volcanic halogen emissions and in particular their speciation and therefore also in the understanding of the bromine chemistry in volcanic plumes (Bobrowski et al., 2007). In this study a gas diffusion denuder sampling method using a 1,3,5-trimethoxybenzene (1,3,5-TMB) coating for the derivatization of reactive halogen species (Rüdiger et al., 2015) was characterized by reaction chamber experiments. The coating proved to be suitable to collect selectively gaseous bromine species with oxidation states of +1 or 0 (such as Br2, BrCl, BrO(H) and BrONO2), while being ignorant to HBr (OS -1). The reaction of 1,3,5-TMB with reactive bromine species gives 1-bromo-2,4,6-trimethoxybenzene (1-bromo-2,4,6-TMB) - other halogens give corresponding

Surface termination structure of α-Ga{sub 2}O{sub 3} film grown by mist chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Tamba, Daiki; Kubo, Osamu, E-mail: okubo@eei.eng.osaka-u.ac.jp; Osaka, Shun; Takahashi, Kazuki; Tabata, Hiroshi; Katayama, Mitsuhiro [Division of Electrical, Electronic and Information Engineering, Graduate School of Engineering, Osaka University, Suita 565-0871 (Japan); Oda, Masaya [Photonics and Electronics Science and Engineering Center, Graduate School of Engineering, Kyoto University, Kyoto 615-8520 (Japan); FLOSFIA Inc., 1-36 Goryoohara, Kyoto 615-8245 (Japan); Kaneko, Kentaro; Fujita, Shizuo [Photonics and Electronics Science and Engineering Center, Graduate School of Engineering, Kyoto University, Kyoto 615-8520 (Japan)

2016-06-20

The surface structure of α-Ga{sub 2}O{sub 3}(0001) grown on an α-Al{sub 2}O{sub 3}(0001) substrate by mist chemical vapor deposition was studied by coaxial impact-collision ion scattering spectroscopy (CAICISS) and atomic force microscopy (AFM). The minimum step height observed in the AFM image was 0.21 ± 0.01 nm, coinciding with the height of three atomic layers of α-Ga{sub 2}O{sub 3}(0001). It was revealed by CAICISS analysis that the surface of α-Ga{sub 2}O{sub 3}(0001) is terminated by a Ga layer followed by an O layer, which is consistent with the surface termination of α-Al{sub 2}O{sub 3}(0001). A structural model taking surface relaxation into account was also constructed by fitting the simulated curve for the azimuth angle dependence of the Ga intensity to the experimental dependence. The resultant structural model is similar to the model of an α-Al{sub 2}O{sub 3}(0001) surface, which indicates analogous behavior in corundum crystals.

Delivery of halogenated very short-lived substances from the west Indian Ocean to the stratosphere during the Asian summer monsoon

Directory of Open Access Journals (Sweden)

A. Fiehn

2017-06-01

Full Text Available Halogenated very short-lived substances (VSLSs are naturally produced in the ocean and emitted to the atmosphere. When transported to the stratosphere, these compounds can have a significant influence on the ozone layer and climate. During a research cruise on RV Sonne in the subtropical and tropical west Indian Ocean in July and August 2014, we measured the VSLSs, methyl iodide (CH3I and for the first time bromoform (CHBr3 and dibromomethane (CH2Br2, in surface seawater and the marine atmosphere to derive their emission strengths. Using the Lagrangian particle dispersion model FLEXPART with ERA-Interim meteorological fields, we calculated the direct contribution of observed VSLS emissions to the stratospheric halogen burden during the Asian summer monsoon. Furthermore, we compare the in situ calculations with the interannual variability of transport from a larger area of the west Indian Ocean surface to the stratosphere for July 2000–2015. We found that the west Indian Ocean is a strong source for CHBr3 (910 pmol m−2 h−1, very strong source for CH2Br2 (930 pmol m−2 h−1, and an average source for CH3I (460 pmol m−2 h−1. The atmospheric transport from the tropical west Indian Ocean surface to the stratosphere experiences two main pathways. On very short timescales, especially relevant for the shortest-lived compound CH3I (3.5 days lifetime, convection above the Indian Ocean lifts oceanic air masses and VSLSs towards the tropopause. On a longer timescale, the Asian summer monsoon circulation transports oceanic VSLSs towards India and the Bay of Bengal, where they are lifted with the monsoon convection and reach stratospheric levels in the southeastern part of the Asian monsoon anticyclone. This transport pathway is more important for the longer-lived brominated compounds (17 and 150 days lifetime for CHBr3 and CH2Br2. The entrainment of CHBr3 and CH3I from the west Indian Ocean to the stratosphere during the

Martian fluid and Martian weathering signatures identified in Nakhla, NWA 998 and MIL 03346 by halogen and noble gas analysis

Science.gov (United States)

Cartwright, J. A.; Gilmour, J. D.; Burgess, R.

2013-03-01

We report argon (Ar) noble gas, Ar-Ar ages and halogen abundances (Cl, Br, I) of Martian nakhlites Nakhla, NWA 998 and MIL 03346 to determine the presence of Martian hydrous fluids and weathering products. Neutron-irradiated samples were either crushed and step-heated (Nakhla only), or simply step-heated using a laser or furnace, and analysed for noble gases using an extension of the 40Ar-39Ar technique to determine halogen abundances. The data obtained provide the first isotopic evidence for a trapped fluid that is Cl-rich, has a strong correlation with 40ArXS (40ArXS = 40Armeasured - 40Arradiogenic) and displays 40ArXS/36Ar of ˜1000 - consistent with the Martian atmosphere. This component was released predominantly in the low temperature and crush experiments, which may suggest a fluid inclusion host. For the halogens, we observe similar Br/Cl and I/Cl ratios between the nakhlites and terrestrial reservoirs, which is surprising given the absence of crustal recycling, organic matter and frequent fluid activity on Mars. In particular, Br/Cl ratios in our Nakhla samples (especially olivine) are consistent with previously analysed Martian weathering products, and both low temperature and crush analyses show a similar trend to the evaporation of seawater. This may indicate that surface brines play an important role on Mars and on halogen assemblages within Martian meteorites and rocks. Elevated I/Cl ratios in the low temperature NWA 998 and MIL 03346 releases may relate to in situ terrestrial contamination, though we are unable to distinguish between low temperature terrestrial or Martian components. Whilst estimates of the amount of water present based on the 36Ar concentrations are too high to be explained by a fluid component alone, they are consistent with a mixed-phase inclusion (gas and fluid) or with shock-implanted Martian atmospheric argon. The observed fluid is dilute (low salinity, but high Br/Cl and I/Cl ratios), contains a Martian atmospheric component

REDUCTION OF ADENOSINE-A1-RECEPTORS IN THE PERFORANT PATHWAY TERMINAL ZONE IN ALZHEIMER HIPPOCAMPUS

NARCIS (Netherlands)

JAARSMA, D; SEBENS, JB; KORF, J

1991-01-01

The cells of origin of the perforant pathway are destroyed in Alzheimer's disease (AD). In rat the adenosine A1-receptors are specifically localized on the perforant path terminals in the molecular layer of the dentate gyrus. In the present study the density of A1-receptors in the hippocampus of

Polyhalogenated Decaborate and 1-Ammoniododecaborate Ions: An Improved Synthesis with Elemental Halogens, and Physicochemical and Chemical Properties

Czech Academy of Sciences Publication Activity Database

Holub, Josef; El Anwar, Suzan; Jelínek, T.; Fojt, Lukáš; Růžičková, Z.; Šolínová, Veronika; Kašička, Václav; Gabel, D.; Grüner, Bohumír

2017-01-01

Roč. 2017, 38/39 (2017), s. 4499-4509 ISSN 1434-1948 R&D Projects: GA TA ČR(CZ) TH01020844 Institutional support: RVO:61388980 ; RVO:68081707 ; RVO:61388963 Keywords : Boranes * Borates * Capillary electrophoresis * Electrochemistry * Halogenation Subject RIV: CA - Inorganic Chemistry ; BO - Biophysics (BFU-R) OBOR OECD: Inorganic and nuclear chemistry ; Biophysics (BFU-R) Impact factor: 2.444, year: 2016

Decomposition of halogenated organic chemicals in ionic liquid by ionizing radiation

International Nuclear Information System (INIS)

Kimura, A.; Taguchi, M.; Kojima, T.; Nagaishi, R.; Hiratsuka, H.

2006-01-01

Introduction: Halogenated organic chemicals such as polychlorodibenzo-p-dioxin, polychlorobiphenyls and hexachlorobenzene are widely spread in water environment. These pollutants are persistent against advanced oxidation treatments such as ozone/UV, ozone/hydrogen peroxide, ionizing radiation and photocatalysts. The ionizing radiation, however, can also produce homogeneously and quantitatively reducing species in water. On the other hand, room temperature ionic liquids (RTILs) have unique properties such as nonflammable, high polarity, low melting point, hydrophobicity and wide electrochemical window. The combined method of reduction by ionizing radiation and RTILs is investigated as a new environmental conservation technology. Experimental: Chlorophenol (CP) is selected as model chemicals having the main frame of halogenated organic chemicals. Each o - , m - and p-CP were irradiated with 60 Co γ-ray in each diethylmethyl(2-methoxy-ethyl)ammonium bis(trifluoromethylsulfonyl)imide (DEMMA- TFSI), diethylmethyl(2-methoxyethyl)-ammonium tetrafluoroborate (DEMMA-BF4), methanol and ethanol as solvent. Decomposition of CP and formation of irradiation products were studied using HPLC, LC-MS and ion chromatography. Results and discussion: Concentration of CP in each solution decreased as a function of dose. G-value was estimated from the slope at the primary stage of the decomposition curve. The G(-CP) and G(Phenol) were shown in Table 1. G(-CP) in the aliphatic alcohols was 0.21 to 0.37, which is lower than G-value of reducing species in the alcohols, e.g. G=1.0 to 1.5 for solvated electron. Since the rate constant for reaction of CP with hydrated electron is 1.3 x 10 9 mol -1 ·dm 3 ·s -1 , the reverse reaction is considered to attribute. G(-CP) in DEMMA-TFSI or DEMMA-BF4 was about 2 to 3 times higher than that in each alcohol. Lifetime of the reducing species in RTILs would be longer than that in each alcohol. G(-CP) in DEMMA-TFSI decreased by adding acetone or oxygen

Dynamics of the central phenylene ring torsional motion in halogenated phenylene ethynylene oligomers

Energy Technology Data Exchange (ETDEWEB)

Pejov, Ljupco [Institute of Chemistry, Department of Physical Chemistry, SS. Cyril and Methodius University, Arhimedova 5, P.O. Box 162, 1000 Skopje(Macedonia, The Former Yugoslav Republic of)], E-mail: ljupcop@iunona.pmf.ukim.edu.mk; La Rosa, Manuela [PST Group- M6, STMicroelectronics, Stradale Primosole 50, 95121 Catania (Italy); Kocarev, Ljupco [Institute for Nonlinear Science, University of California, San Diego 9500 Gilman, Drive, La Jolla, CA 92093-0402 (United States); Macedonian Academy of Sciences and Arts, bul. Krste Misirkov 2, P.O. Box 428, 1000 Skopje (Macedonia, The Former Yugoslav Republic of)

2007-11-09

The dynamics of intramolecular torsional motion of central phenylene ring in a series of phenylene ethynylene oligomer derivatives was investigated. On the basis of calculated hindered rotational potentials corresponding to this motion, the torsional energy levels were obtained by solving the torsional Schroedinger equation. Subsequently, the torsional correlation time and transition probability was computed within the Bloembergen-Purcell-Pound (BPP) formalism, considering both the classical and quantum mechanical tunneling contributions to the intramolecular rotation. The results were interpreted in the context of molecular conductivity switching behavior of the considered series of compounds. Also some other parameters relevant to molecular admittance were calculated, such as the HOMO-LUMO energy difference and the spatial extent of the frontier molecular orbitals. Classical electrostatic arguments were applied to understand the physical basis of the conformational stability differences in the studied compounds. It was found that halogenation of the central phenylene ring may be used for fine-tuning of molecular conduction behavior, in the sense of modulating the HOMO-LUMO energy difference, the spatial extent of frontier MOs, as well as the barrier height to torsional motion of the central phenylene ring. The time scale of the temperature induced stochastic conformational switching between the 'on' and 'off' states, along with the corresponding transition probability could be varied by an order of magnitude upon halogenation of the central phenylene ring. The tunneling contributions to the torsional correlation time were found to be of minor importance in this context, and this quantity may be quite correctly estimated with the classical BPP approach.

Dynamics of the central phenylene ring torsional motion in halogenated phenylene ethynylene oligomers

International Nuclear Information System (INIS)

Pejov, Ljupco; La Rosa, Manuela; Kocarev, Ljupco

2007-01-01

The dynamics of intramolecular torsional motion of central phenylene ring in a series of phenylene ethynylene oligomer derivatives was investigated. On the basis of calculated hindered rotational potentials corresponding to this motion, the torsional energy levels were obtained by solving the torsional Schroedinger equation. Subsequently, the torsional correlation time and transition probability was computed within the Bloembergen-Purcell-Pound (BPP) formalism, considering both the classical and quantum mechanical tunneling contributions to the intramolecular rotation. The results were interpreted in the context of molecular conductivity switching behavior of the considered series of compounds. Also some other parameters relevant to molecular admittance were calculated, such as the HOMO-LUMO energy difference and the spatial extent of the frontier molecular orbitals. Classical electrostatic arguments were applied to understand the physical basis of the conformational stability differences in the studied compounds. It was found that halogenation of the central phenylene ring may be used for fine-tuning of molecular conduction behavior, in the sense of modulating the HOMO-LUMO energy difference, the spatial extent of frontier MOs, as well as the barrier height to torsional motion of the central phenylene ring. The time scale of the temperature induced stochastic conformational switching between the 'on' and 'off' states, along with the corresponding transition probability could be varied by an order of magnitude upon halogenation of the central phenylene ring. The tunneling contributions to the torsional correlation time were found to be of minor importance in this context, and this quantity may be quite correctly estimated with the classical BPP approach

Measurements of IO in the Tropical Marine Boundary Layer using Laser-Induced Fluorescence Spectroscopy

Science.gov (United States)

Walker, H.; Ingham, T.; Heard, D. E.

2012-12-01

Halogenated short-lived substances (VSLS) are emitted from the oceans by marine species such as macroalgae and phytoplankton and contribute to halogen loading in the troposphere and lower stratosphere. Transport of halogenated VSLS into the stratosphere occurs mainly in the tropics, where ascending warm air carries them aloft, and leads to catalytic depletion of stratospheric ozone on a global scale and formation of the Antarctic ozone hole. The tropical marine environment is therefore an important region in which to study the effects of these short-lived halogen species on ozone depletion. The SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) project combines ship-borne, aircraft-based and ground-based measurements in and over the South China Sea and the Sulu Sea, and around the coast of Malaysian Borneo, to reduce uncertainties in the amount of halogenated VSLS reaching the stratosphere, the associated ozone depletion, and the effects of a changing climate on these processes. In this work we present measurements of IO radicals made onboard the German research vessel Sonne during SHIVA, between Singapore and Manila. IO is formed via photolysis of iodine-containing source gases (e.g. I2, CH3I) to produce I atoms, which react with ozone. It is therefore an important species to consider when assessing the impacts of halogen chemistry on ozone depletion. Measurements of IO were made over a two-week period by the University of Leeds Laser-Induced Fluorescence (LIF) instrument, which excites IO radicals at λ ~ 445 nm and detects the resultant fluorescence at λ ~ 512 nm. A suite of supporting gas- and aqueous-phase measurements were also made, including concentrations of halocarbons (e.g. CHBr3, CH3I), trace pollutant gases (e.g. CO, O3, NOx), and biological parameters (e.g. abundance and speciation of phytoplankton). Preliminary data analysis indicates that IO was detected above the instrumental limit of detection (0.3 pptv for a 30 minute averaging

A comparative evaluation of the shear bond strength of five different orthodontic bonding agents polymerized using halogen and light-emitting diode curing lights: An in vitro investigation

Directory of Open Access Journals (Sweden)

Sujoy Banerjee

2011-01-01

Full Text Available Purpose: With the introduction of photosensitive (light-activated restorative materials in orthodontics, various methods have been suggested to enhance the polymerization of the materials used, including use of more powerful light curing devices. Bond strength is an important property and determines the amount of force delivered and the treatment duration. Many light-cured bonding materials have become popular but it is the need of the hour to determine the bonding agent that is the most efficient and has the desired bond strength. Aim: To evaluate and compare the shear bond strengths of five different orthodontic light cure bonding materials cured with traditional halogen light and low-intensity light-emitting diode (LED light curing unit. Materials and Methods: 100 human maxillary premolar teeth, extracted for orthodontic purpose, were used to prepare the samples. 100 maxillary stainless steel bicuspid brackets of 0.018 slot of Roth prescription, manufactured by D-tech Company, were bonded to the prepared tooth surfaces of the mounted samples using five different orthodontic bracket bonding light-cured materials, namely, Enlight, Fuji Ortho LC (resin-modified glass ionomer cement, Orthobond LC, Relybond, and Transbond XT. The bond strength was tested on an Instron Universal testing machine (model no. 5582. Results: In Group 1 (halogen group, Enlight showed the highest shear bond strength (16.4 MPa and Fuji Ortho LC showed the least bond strength (6.59 MPa (P value 0.000. In Group 2 (LED group, Transbond showed the highest mean shear bond strength (14.6 MPa and Orthobond LC showed the least mean shear bond strength (6.27 MPa (P value 0.000. There was no statistically significant difference in the shear bond strength values of all samples cured using either halogen (mean 11.49 MPa or LED (mean 11.20 MPa, as the P value was 0.713. Conclusion: Polymerization with both halogen and LED resulted in shear bond strength values which were above the

Terminal load response law of coaxial cable to continuous wave electromagnetic irradiation

International Nuclear Information System (INIS)

Pan Xiaodong; Wei Guanghui; Li Xinfeng; Lu Xinfu

2012-01-01

In order to study the coupling response law of continuous wave electromagnetic irradiation to coaxial cable, the typical RF coaxial cable is selected as the object under test. The equipment or subsystem connected by coaxial cable is equivalent to a lumped load. Continuous wave irradiation effect experiments under different conditions are carried out to analyze the terminal load response law of coaxial cable. The results indicate that the coaxial cable has a frequency selecting characteristic under electromagnetic irradiation, and the terminal load response voltage peak appears at a series of discrete frequency points where the test cable's relative lengths equal to semi-integers. When the coaxial cable is irradiated by continuous wave, the induced sheath current converts to the differential-mode induced voltage between inner conductor and shielding layer through transfer impedance, and the internal resistance of induced voltage source is the characteristic impedance of the coaxial cable. The change in terminal load value has no influence on the response curve. The voltages on the terminal load and the internal resistance of equivalent induced voltage source obey the principle of voltage division. Moreover, when the sheath current on the coaxial cable is in resonance, the distributed induced voltage between adjacent current nodes is in the same polarity, which can be equivalent to a single induced voltage source. The induced voltage source which is adjacent to the terminal load plays the leading role in the irradiation response process. (authors)

CONTAINER TERMINALS IN EUROPE

Directory of Open Access Journals (Sweden)

Bart W. WIEGMANS

2001-01-01

Full Text Available This paper aims to address the linkage between logistics (in particular, the management of marketing channel flows and transport markets, while also the interaction between these two markets and intermodal container terminals is analysed. The marketing channel theory is used to describe all relevant actors and flows that run through marketing channels, starting with customer needs and ending with customer satisfaction. Porter's theory of competitive advantages is used to review competitive forces in both markets. Finally, a competitor analysis is performed for the logistics and transport market. These theories are applied so as to be able to determine the competitive position of intermodal container terminals with a view to the management of marketing channel flows and the physical transport of freight flows. Hence, the central question of this paper is: Which markets are served by intermodal container terminals and with whom are they competing? At present, neither the maritime container terminals nor the continental container terminals appear to have a significant influence in the logistics service market; they concentrate mainly on the physical movement of containers (transshipment. Furthermore, maritime container terminals and continental container terminals are not dominant players in the transport service market. Our conclusion is that continental terminals are predominantly competing with unimodal road transport, with neighbouring continental terminals and with barge transport companies.

Transformation mechanism of n-butyl terminated Si nanoparticles embedded into Si1-xCx nanocomposites mixed with Si nanoparticles and C atoms

International Nuclear Information System (INIS)

Shin, J.W.; Oh, D.H.; Kim, T.W.; Cho, W.J.

2009-01-01

Bright-field transmission electron microscopy (TEM) images, high-resolution TEM (HRTEM) images, and fast-Fourier transformed electron-diffraction patterns showed that n-butyl terminated Si nanoparticles were aggregated. The formation of Si 1-x C x nanocomposites was mixed with Si nanoparticles and C atoms embedded in a SiO 2 layer due to the diffusion of C atoms from n-butyl termination shells into aggregated Si nanoparticles. Atomic force microscopy (AFM) images showed that the Si 1-x C x nanocomposites mixed with Si nanoparticles and C atoms existed in almost all regions of the SiO 2 layer. The formation mechanism of Si nanoparticles and the transformation mechanism of n-butyl terminated Si nanoparticles embedded into Si 1-x C x nanocomposites mixed with Si nanoparticles and C atoms are described on the basis of the TEM, HRTEM, and AFM results. These results can help to improve the understanding of the formation mechanism of Si nanoparticles.

Visual communication and terminal equipment

International Nuclear Information System (INIS)

Kang, Cheol Hui

1988-06-01

This book is divided two parts about visual communication and terminal equipment. The first part introduces visual communication, which deals with foundation of visual communication, technique of visual communication, equipment of visual communication, a facsimile and pictorial image system. The second part contains terminal equipment such as telephone, terminal equipment for data transmission on constitution and constituent of terminal equipment for data transmission, input device and output device, terminal device and up-to-date terminal device.

Visual communication and terminal equipment

Energy Technology Data Exchange (ETDEWEB)

Kang, Cheol Hui

1988-06-15

This book is divided two parts about visual communication and terminal equipment. The first part introduces visual communication, which deals with foundation of visual communication, technique of visual communication, equipment of visual communication, a facsimile and pictorial image system. The second part contains terminal equipment such as telephone, terminal equipment for data transmission on constitution and constituent of terminal equipment for data transmission, input device and output device, terminal device and up-to-date terminal device.

Legacy and alternative halogenated flame retardants in human milk in Europe: Implications for children's health.

Science.gov (United States)

Čechová, Eliška; Vojta, Šimon; Kukučka, Petr; Kočan, Anton; Trnovec, Tomáš; Murínová, Ľubica Palkovičová; de Cock, Marijke; van de Bor, Margot; Askevold, Joakim; Eggesbø, Merete; Scheringer, Martin

2017-11-01

In this study, 10 polybrominated diphenyl ethers (PBDEs) and 19 alternative halogenated flame retardants (AFRs) were determined in >450 human milk samples across three European countries, representing northern, western and eastern Europe. This study provides first insights into the occurrence of selected AFRs in mother milk samples and compares them among three European countries. Sums of median concentrations of the most frequently detected PBDEs were 2.16, 0.88 and 0.45ngg -1 lipid weight (lw) in Norway, the Netherlands and Slovakia, respectively. The sum of the concentrations of AFRs ranged from 0.14 to 0.25ngg -1 lw in all countries, which was 2 to 15 times less compared to Σ 7 PBDEs. The Penta-BDE replacement, bis(2-ethylhexyl) tetrabromophthalate, BEH-TEBP, was present at the greatest concentrations of any of the AFRs and in some samples exceeded concentrations of BDE 47 and BDE 153. Four AFRs including bromobenzenes (hexabromobenzene, pentabromobenzene, pentabromotoluene) and another Penta-BDE replacement (2-ethylhexyl-2,3,4,5-tetrabromobenzoate, EH-TBB) were detected in >42% of all human milk samples. Because of the potential developmental neurotoxicity of the halogenated flame retardants, infant dietary intakes via breastfeeding were estimated; in four cases the intakes of BDE 47 exceeded the reference dose indicating that the present concentrations may pose a risk for children. Copyright © 2017 Elsevier Ltd. All rights reserved.

TEGDMA and UDMA monomers released from composite dental material polymerized with diode and halogen lamps.

Science.gov (United States)

Wacławczyk, Agnieszka; Postek-Stefańska, Lidia; Pietraszewska, Daria; Birkner, Ewa; Zalejska-Fiolka, Jolanta; Wysoczańska-Jankowicz, Iwona

2018-03-20

More than 35 substances released from composite fillings have been identified. Among these, basic monomers and the so-called co-monomers are most often reported. The substances released from polymer-based materials demonstrate allergenic, cytotoxic, genotoxic, mutagenic, embryotoxic, teratogenic, and estrogenic properties. The aim of this study was to measure the amounts of triethylene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) monomers released from composite dental fillings to citrate-phosphate buffer with the pH of 4, 6, 8 after 24 h and 6 months from the polymerization. Ten samples for each polymerization method had been made from the composite material (Filtek Supreme XT, 3M ESPE, St. Paul, USA), which underwent polymerization using the following lamps: halogen lamp (Translux CL, Heraeus Kulzer, Hanau, Germany) (sample H) and diode lamp (Elipar Freelight 2, 3M ESPE), with soft start function (group DS) and without that function (group DWS). It has been demonstrated that the type of light-curing units has a significant impact on the amount of TEGDMA and UDMA released. The amount of UDMA and TEGDMA monomers released from composite fillings differed significantly depending on the source of polymerization applied, as well as the pH of the solution and sample storage time. Elution of the monomers from composite material polymerized using halogen lamp was significantly greater as compared to curing with diode lamps.

Synthesis and Pharmacology of Halogenated δ-Opioid-Selective [D-Ala2]Deltorphin II Peptide Analogues

Science.gov (United States)

Pescatore, Robyn; Marrone, Gina F.; Sedberry, Seth; Vinton, Daniel; Finkelstein, Netanel; Katlowitz, Yitzchak E.; Pasternak, Gavril W.; Wilson, Krista R.; Majumdar, Susruta

2015-01-01

Deltorphins are naturally occurring peptides produced by the skin of the giant monkey frog (Phyllomedusa bicolor). They are δ-opioid receptor-selective agonists. Herein, we report the design and synthesis of a peptide, Tyr-D-Ala-(pI)Phe-Glu-Ile-Ile-Gly-NH2 3 (GATE3-8), based on the [D-Ala2]deltorphin II template, which is δ-selective in in vitro radioligand binding assays over the μ- and κ-opioid receptors. It is a full agonist in [35S]GTPγS functional assays and analgesic when administered supraspinally to mice. Analgesia of 3 (GATE3-8) is blocked by the selective δ receptor antagonist naltrindole, indicating that the analgesic action of 3 is mediated by the δ-opioid receptor. We have established a radioligand in which 125I isincorporated into 3 (GATE3-8). The radioligand has a KD of 0.1 nM in Chinese hamster ovary (CHO) cells expressing the δ receptor. Additionally, a series of peptides based on 3 (GATE3-8) was synthesized by incorporating various halogens in the para position on the aromatic ring of Phe3. The peptides were characterized for binding affinity at the μ-, δ-, and κ-opioid receptors, which showed a linear correlation between binding affinity and the size of the halogen substituent. These peptides may be interesting tools for probing δ-opioid receptor pharmacology. PMID:25844930

Synthesis and pharmacology of halogenated δ-opioid-selective [d-Ala(2)]deltorphin II peptide analogues.

Science.gov (United States)

Pescatore, Robyn; Marrone, Gina F; Sedberry, Seth; Vinton, Daniel; Finkelstein, Netanel; Katlowitz, Yitzchak E; Pasternak, Gavril W; Wilson, Krista R; Majumdar, Susruta

2015-06-17

Deltorphins are naturally occurring peptides produced by the skin of the giant monkey frog (Phyllomedusa bicolor). They are δ-opioid receptor-selective agonists. Herein, we report the design and synthesis of a peptide, Tyr-d-Ala-(pI)Phe-Glu-Ile-Ile-Gly-NH2 3 (GATE3-8), based on the [d-Ala(2)]deltorphin II template, which is δ-selective in in vitro radioligand binding assays over the μ- and κ-opioid receptors. It is a full agonist in [(35)S]GTPγS functional assays and analgesic when administered supraspinally to mice. Analgesia of 3 (GATE3-8) is blocked by the selective δ receptor antagonist naltrindole, indicating that the analgesic action of 3 is mediated by the δ-opioid receptor. We have established a radioligand in which (125)I is incorporated into 3 (GATE3-8). The radioligand has a KD of 0.1 nM in Chinese hamster ovary (CHO) cells expressing the δ receptor. Additionally, a series of peptides based on 3 (GATE3-8) was synthesized by incorporating various halogens in the para position on the aromatic ring of Phe(3). The peptides were characterized for binding affinity at the μ-, δ-, and κ-opioid receptors, which showed a linear correlation between binding affinity and the size of the halogen substituent. These peptides may be interesting tools for probing δ-opioid receptor pharmacology.

Microwave assisted pyrolysis of halogenated plastics recovered from waste computers.

Science.gov (United States)

Rosi, Luca; Bartoli, Mattia; Frediani, Marco

2018-03-01

Microwave Assisted Pyrolysis (MAP) of the plastic fraction of Waste from Electric and Electronic Equipment (WEEE) from end-life computers was run with different absorbers and set-ups in a multimode batch reactor. A large amount of various different liquid fractions (up to 76.6wt%) were formed together with a remarkable reduction of the solid residue (up to 14.2wt%). The liquid fractions were characterized using the following different techniques: FT-IR ATR, 1 H NMR and a quantitative GC-MS analysis. The liquid fractions showed low density and viscosity, together with a high concentration of useful chemicals such as styrene (up to 117.7mg/mL), xylenes (up to 25.6mg/mL for p-xylene) whereas halogenated compounds were absent or present in a very low amounts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Formation of the outer layer of the Dictyostelium spore coat depends on the inner-layer protein SP85/PsB.

Science.gov (United States)

Metcalf, Talibah; Kelley, Karen; Erdos, Gregory W; Kaplan, Lee; West, Christopher M

2003-02-01

The Dictyostelium spore is surrounded by a 220 microm thick trilaminar coat that consists of inner and outer electron-dense layers surrounding a central region of cellulose microfibrils. In previous studies, a mutant strain (TL56) lacking three proteins associated with the outer layer exhibited increased permeability to macromolecular tracers, suggesting that this layer contributes to the coat permeability barrier. Electron microscopy now shows that the outer layer is incomplete in the coats of this mutant and consists of a residual regular array of punctate electron densities. The outer layer is also incomplete in a mutant lacking a cellulose-binding protein associated with the inner layer, and these coats are deficient in an outer-layer protein and another coat protein. To examine the mechanism by which this inner-layer protein, SP85, contributes to outer-layer formation, various domain fragments were overexpressed in forming spores. Most of these exert dominant negative effects similar to the deletion of outer-layer proteins, but one construct, consisting of a fusion of the N-terminal and Cys-rich C1 domain, induces a dense mat of novel filaments at the surface of the outer layer. Biochemical studies show that the C1 domain binds cellulose, and a combination of site-directed mutations that inhibits its cellulose-binding activity suppresses outer-layer filament induction. The results suggest that, in addition to a previously described early role in regulating cellulose synthesis, SP85 subsequently contributes a cross-bridging function between cellulose and other coat proteins to organize previously unrecognized structural elements in the outer layer of the coat.

N-Chloro and N-bromosaccharins: valuable reagents for halogenation of electron rich aromatics and cohalogenation of alkenes

Directory of Open Access Journals (Sweden)

Souza Soraia P. L. de

2003-01-01

Full Text Available N-Chloro- and N-bromosaccharins react with electron rich aromatic compounds (anisole, acetanilide, N,N-dimethylaniline producing halogenated compounds. The reaction with N-bromosaccharin gives para- substituted compounds only, whereas N-chlorosaccharin produces orto and para mixtures (para isomer predominantly, ca. 4-5 : 1. The reactions of the N-halosaccharins with alkenes (cyclohexene, styrene, a-methylstyrene, and 1-hexene give the corresponding halohydrins.

Chloramphenicol Biosynthesis: The Structure of CmlS, a Flavin-Dependent Halogenase Shwing a Covalent Flavin-Aspartate Bond

International Nuclear Information System (INIS)

Podzelinska, K.; Latimer, R.; Bhattacharya, A.; Vining, L.; Zechel, D.; Jia, Z.

2010-01-01

Chloramphenicol is a halogenated natural product bearing an unusual dichloroacetyl moiety that is critical for its antibiotic activity. The operon for chloramphenicol biosynthesis in Streptomyces venezuelae encodes the chloramphenicol halogenase CmlS, which belongs to the large and diverse family of flavin-dependent halogenases (FDH's). CmlS was previously shown to be essential for the formation of the dichloroacetyl group. Here we report the X-ray crystal structure of CmlS determined at 2.2 (angstrom) resolution, revealing a flavin monooxygenase domain shared by all FDHs, but also a unique 'winged-helix' C-terminal domain that creates a T-shaped tunnel leading to the halogenation active site. Intriguingly, the C-terminal tail of this domain blocks access to the halogenation active site, suggesting a structurally dynamic role during catalysis. The halogenation active site is notably nonpolar and shares nearly identical residues with Chondromyces crocatus tyrosyl halogenase (CndH), including the conserved Lys (K71) that forms the reactive chloramine intermediate. The exception is Y350, which could be used to stabilize enolate formation during substrate halogenation. The strictly conserved residue E44, located near the isoalloxazine ring of the bound flavin adenine dinucleotide (FAD) cofactor, is optimally positioned to function as a remote general acid, through a water-mediated proton relay, which could accelerate the reaction of the chloramine intermediate during substrate halogenation, or the oxidation of chloride by the FAD(C4α)-OOH intermediate. Strikingly, the 8α carbon of the FAD cofactor is observed to be covalently attached to D277 of CmlS, a residue that is highly conserved in the FDH family. In addition to representing a new type of flavin modification, this has intriguing implications for the mechanism of FDHs. Based on the crystal structure and in analogy to known halogenases, we propose a reaction mechanism for CmlS.

ESR studies of Bunsen-type methane-air flames. II. The effects of the addition of halogenated compounds to the secondary air on the hydrogen atoms in the flame

Energy Technology Data Exchange (ETDEWEB)

Noda, S; Fujimoto, S; Claesson, O; Yoshida, H

1983-09-01

Hydrogen atoms in a methane-air Bunsen-type flame were detected by the flame-in-cavity ESR method. The addition of a halogenated compound to the secondary air reduced the H-atom concentration linearly with an increase in additive concentration. These 8 halogenated compounds examined showed increased effectiveness in scavenging H atoms in this order: hydrochloric acid < dichlorodifluoromethane < chloroform < methyl chloride < methylene chloride < trichlorofluoromethane < carbon tetrachlorie < methyl bromide. The chemical effects of these additives on the combustion reactions agree well with the inhibitor indices for these compounds. 14 references, 3 figures.

A transparent electrochromic metal-insulator switching device with three-terminal transistor geometry

Science.gov (United States)

Katase, Takayoshi; Onozato, Takaki; Hirono, Misako; Mizuno, Taku; Ohta, Hiromichi

2016-05-01

Proton and hydroxyl ion play an essential role for tuning functionality of oxides because their electronic state can be controlled by modifying oxygen off-stoichiometry and/or protonation. Tungsten trioxide (WO3), a well-known electrochromic (EC) material for smart window, is a wide bandgap insulator, whereas it becomes a metallic conductor HxWO3 by protonation. Although one can utilize electrochromism together with metal-insulator (MI) switching for one device, such EC-MI switching cannot be utilized in current EC devices because of their two-terminal structure with parallel-plate configuration. Here we demonstrate a transparent EC-MI switchable device with three-terminal TFT-type structure using amorphous (a-) WO3 channel layer, which was fabricated on glass substrate at room temperature. We used water-infiltrated nano-porous glass, CAN (calcium aluminate with nano-pores), as a liquid-leakage-free solid gate insulator. At virgin state, the device was fully transparent in the visible-light region. For positive gate voltage, the active channel became dark blue, and electrical resistivity of the a-WO3 layer drastically decreased with protonation. For negative gate voltage, deprotonation occurred and the active channel returned to transparent insulator. Good cycleability of the present transparent EC-MI switching device would have potential for the development of advanced smart windows.

Direct determination of halogens in powdered geological and environmental samples using isotope dilution laser ablation ICP-MS

Science.gov (United States)

Boulyga, Sergei F.; Heumann, Klaus G.

2005-04-01

Laser ablation inductively coupled plasma isotope dilution mass spectrometry (LA-ICP-IDMS) with a special laser ablation system for bulk analyses (LINA-Spark(TM)-Atomiser) was applied for direct determinations of chlorine, bromine, and iodine in rock and sediment samples. Special attention was focused on possible inter-halogen fractionations and analyte/spike isotope fractionations by using LA-ICP-MS and LA-ICP-IDMS, respectively. A variation of Br/Cl and I/Cl element intensity ratios by a factor of 1.3-3 was observed when changing the nebulizer gas flow rate in the range of 0.84-1.0 L min-1 and the laser power density in the range of 2-10 GW cm-2, respectively. When using an internal standard for halogen quantification in LA-ICP-MS, this inter-element fractionation can cause systematic errors, which can be avoided by applying the isotope dilution technique. However, at high laser power densities (>5.7 GW cm-2 for iodine and >4.0 GW cm-2 for bromine and chlorine) the corresponding measured isotope ratio of the isotope-diluted sample deviates significantly from the target value. Under optimised conditions concentrations in the range of 30 [mu]g g-1-16 × 103 [mu]g g-1 for chlorine, <2-140 [mu]g g-1 for bromine, and <0.1-31 [mu]g g-1 for iodine were determined by LA-ICP-IDMS in two sediment reference materials (SRM 1646, SRM 2704) and three rock reference samples (GS-N, Granite; BX-N, Bauxite; DT-N, Disthene), which have not been certified for these halogens. The sediment results agree well within the given uncertainties with indicative values by different methods and the results of the rock samples with those obtained by negative thermal ionisation isotope dilution mass spectrometry. The detection limits of LA-ICP-IDMS are 8 [mu]g g-1 for chlorine, 1.7 [mu]g g-1 for bromine, and 0.1 [mu]g g-1 for iodine.

Guidelines for the determination of halogenated dibenzo-p-dioxins and dibenzofurans in commercial products. Final report, March 1985-July 1986

International Nuclear Information System (INIS)

Steele, D.H.; Stanley, J.S.

1987-01-01

The determination of halogenated dibenzo-p-dioxins (HDDs) and dibenzofurans (HDFs) in commercial products require specific and sensitive analytical procedures. The development of methods for the measurement of HDD and HDF in commercial products is complicated by the diverse range of matrices, the potentially large number of halogenated (specifically chloro, bromo, or bromo/chloro) HDD and HDF congeners and potential interference due to major components of the product matrices. This report provides: (1) a review of the literature pertaining to commercial product analyses for HDDs and HDFs; (2) detail on the total number of bromo, chloro, and bromo/chloro HDDs and HDFs; (3) a tentative scheme for the analysis of HDDs and HDFs in diverse matrices; and (4) guidelines for the high-resolution gas chromatography/ mass spectrometry or electron capture detector analysis of commercial products for HDDs and HDFs. The guidelines specify a rigorous OA/QC program for the analysis of the commercial products

Synthesis of 4-Halogenated 3-Fluoro-6-methoxyquinolines: Key Building Blocks for the Synthesis of Antibiotics

DEFF Research Database (Denmark)

Flagstad, Thomas; Petersen, Mette Terp; Hinnerfeldt, Daniel Michael

2014-01-01

A practical and scalable 4-step route is presented for the synthesis of 4-bromo-3-fluoro-6-methoxyoquinoline and 3-fluoro-4-iodo-6-methoxyoquinoline from readily available 2,4-dichloro-3-fluoroquinoline with an overall yield of 81-85%. Halogenated quinoline building blocks have found much use in ...... in antimicrobial drug discovery, and the method reported here would be useful for the synthesis of these compounds. © Georg Thieme Verlag....

Controlling the surface termination of NdGaO3 (110): the role of the gas atmosphere.

Science.gov (United States)

Cavallaro, Andrea; Harrington, George F; Skinner, Stephen J; Kilner, John A

2014-07-07

In this work the effect of gas atmosphere on the surface termination reconstruction of single crystal NdGaO3 (110) (NGO) during thermal annealing was analyzed. Using Low Energy Ion Scattering (LEIS) it has been possible to study the chemical composition of the first atomic layer of treated NGO single crystal samples. NGO has been analyzed both as-received and after a specific thermal treatment at 1000 °C under different gas fluxes (argon, nitrogen, static air, synthetic air, nitrogen plus 5% hydrogen and wet synthetic air respectively). Thermal annealing of perovskite single crystals, as already reported in the literature, is used to obtain a fully A-cation surface termination. Nevertheless the effect of the gas-atmosphere on this process has not been previously reported. By the use of sequential low energy Ar(+) sputtering combined with the primary ion LEIS analysis, the reconstruction of the outermost atomic layers has allowed the clarification of the mechanism of NGO neodymium surface enrichment. It is proposed that the gallium at the surface is submitted to a reduction/evaporation mechanism caused by low oxygen partial pressure and/or high water pressure in the vector gas. Below the first surface atomic layers of an as-received NGO single-crystal a gallium-rich phase has also been observed.

ACCUMULATION OF POLY-B-HYDROXYBUTYRATE IN A METHANE- ENRICHED, HALOGENATED, HYDROCARBON-DEGRADING SOIL COLUMN: IMPLICATIONS FOR MICROBIAL COMMUNITY STRUCTURE AND NUTRITIONAL STATUS

Science.gov (United States)

The prokarotic, endogenous storage polymer poly--hydroxybutyrate (PHB) accumulated in soil from a methane-enriched, halogenated hydrocarbon-degrading soil column. Based on phospholipid ester-linked fatty acid (PLFA) profiles, this mocrocosm has been previously reported to be sign...

Negative Halogen Ions for Fusion Applications

International Nuclear Information System (INIS)

Grisham, L.R.; Kwan, J.W.; Hahto, S.K.; Hahto, S.T.; Leung, K.N.; Westenskow, G.

2006-01-01

Over the past quarter century, advances in hydrogen negative ion sources have extended the usable range of hydrogen isotope neutral beams to energies suitable for large magnetically confined fusion devices. Recently, drawing upon this experience, negative halogen ions have been proposed as an alternative to positive ions for heavy ion fusion drivers in inertial confinement fusion, because electron accumulation would be prevented in negative ion beams, and if desired, the beams could be photo-detached to neutrals. This paper reports the results of an experiment comparing the current density and beam emittance of Cl+ and Cl- extracted from substantially ion-ion plasmas with that of Ar+ extracted from an ordinary electron-ion plasma, all using the same source, extractor, and emittance scanner. At similar discharge conditions, the Cl- current was typically 85-90% of the positive chlorine current, with an e-/ Cl- ratio as low as seven without grid magnets. The Cl- was as much as 76% of the Ar+ current from a discharge with the same RF drive. The minimum normalized beam emittance and inferred ion temperatures of Cl+, Cl-, and Ar+ were all similar, so the current density and optical quality of Cl- appear as suitable for heavy ion fusion driver applications as a positive noble gas ion of similar mass. Since F, I, and Br should all behave similarly in an ion source, they should also be suitable as driver beams

The role of metasomatism in the balance of halogens in ore-forming process at porphyry Cu-Mo deposits

Science.gov (United States)

Berzina, A. N.

2009-04-01

Volatile components play an important role in the evolution of ore-magmatic systems and their ore potential. Of special interest are fluorine and chlorine compounds that principally control the transportation of ore elements by the fluid in a magmatic process and under high-temperature hydrothermal conditions. Study of the evolution of fluorine-chlorine activity in the ore-forming process and their source is usually based on analysis of their magmatic history, whereas the additional source of fluorine and chlorine released during metasomatic alteration of rocks hosting mineralization is poorly discussed in the existing literature. Based on microprobe data on Cl and F abundances in halogen-containing minerals (biotite, amphibole, apatite, titanite) in intrusive rocks and their hydrothermally altered varieties, the role of metasomatic processes in the balance of volatiles in the ore-forming system is discussed by the example of porphyry Cu-Mo deposits of Siberia (Russia) and Mongolia. Two groups of the deposits are considered: copper-molybdenum (Erdenetiin Ovoo, Mongolia and Aksug, Russia) with prevailing propylitic and phyllic alteration and molybdenum-copper (Sora, Russia), with predominant potassic alteration. All types of hydrothermal alterations have led to drastic decrease in Cl contents in metasomatic minerals as compared with halogen-containing magmatic minerals. All studied deposits (particularly those where propylitic and phyllic alteration were developed) show a nearly complete chlorine removal from altered halogen-containing rock-forming minerals (biotite and amphibole). The Cl content in amphibole decreases several times at the stage of replacement with actinolite in the process of propylitization. In the later chlorites (ripidolite and brunsvigite) that replace amphibole, actinolite, and biotite, chlorine is not detected by microprobe (detection limit 0.01-0.02% Cl). Chlorine was also not detected in white micas (muscovite-phengite series) in quartz

The 79,81Br and 127I NQR spectra of some halogenated anions of nido-7,8-dicarbaundecaborates

International Nuclear Information System (INIS)

Semin, G.K.; Zakharkin, L.I.; Kuznetsov, S.I.; Zhigareva, G.G.; Bryukhova, E.V.

1998-01-01

Spectra of nuclear quadrupole resonance of bromine and iodine atoms in the series of halogenated anions of cesium nido-7,8-dicarbaundecaborates have been studied. Considerable shift of the spectrum in the low-frequency range compared to closo-carborane derivatives can be explained by negative charge localization in anion of nido-7,8-dicarbaundecaborates with its certain prevalence in the pentagonal plane [ru

Performance assessment of semiempirical molecular orbital methods in describing halogen bonding: quantum mechanical and quantum mechanical/molecular mechanical-molecular dynamics study.

Science.gov (United States)

Ibrahim, Mahmoud A A

2011-10-24

The performance of semiempirical molecular-orbital methods--MNDO, MNDO-d, AM1, RM1, PM3 and PM6--in describing halogen bonding was evaluated, and the results were compared with molecular mechanical (MM) and quantum mechanical (QM) data. Three types of performance were assessed: (1) geometrical optimizations and binding energy calculations for 27 halogen-containing molecules complexed with various Lewis bases (Two of the tested methods, AM1 and RM1, gave results that agree with the QM data.); (2) charge distribution calculations for halobenzene molecules, determined by calculating the solvation free energies of the molecules relative to benzene in explicit and implicit generalized Born (GB) solvents (None of the methods gave results that agree with the experimental data.); and (3) appropriateness of the semiempirical methods in the hybrid quantum-mechanical/molecular-mechanical (QM/MM) scheme, investigated by studying the molecular inhibition of CK2 protein by eight halobenzimidazole and -benzotriazole derivatives using hybrid QM/MM molecular-dynamics (MD) simulations with the inhibitor described at the QM level by the AM1 method and the rest of the system described at the MM level. The pure MM approach with inclusion of an extra point of positive charge on the halogen atom approach gave better results than the hybrid QM/MM approach involving the AM1 method. Also, in comparison with the pure MM-GBSA (generalized Born surface area) binding energies and experimental data, the calculated QM/MM-GBSA binding energies of the inhibitors were improved by replacing the G(GB,QM/MM) solvation term with the corresponding G(GB,MM) term.

Antecedents of Customer Relationship Termination

DEFF Research Database (Denmark)

Geersbro, Jens; Ritter, Thomas

To end business relationships, or to more actively terminate relationships, has long been acknowledged as part of customer relationship management. However, compared to other elements such as initiation and maintenance of relationships, little is known about the termination of business...... relationships as a managerial task. This paper contributes by (1) developing a conceptualization of relationship termination competence and (2) analyzing its antecedents. The empirical results identify termination acceptance, definition non-customers, organizational relationship termination routines......, and motivation as significant antecedents. Because of this, managers need to develop their organizations in order to use relationship termination as a vital strategy....

LED and Halogen Light Transmission through a CAD/CAM Lithium Disilicate Glass-Ceramic.

Science.gov (United States)

Pereira, Carolina Nemesio de Barros; De Magalhães, Cláudia Silami; Daleprane, Bruno; Peixoto, Rogéli Tibúrcio Ribeiro da Cunha; Ferreira, Raquel da Conceição; Cury, Luiz Alberto; Moreira, Allyson Nogueira

2015-01-01

The effect of thickness, shade and translucency of CAD/CAM lithium disilicate glass-ceramic on light transmission of light-emitting diode (LED) and quartz-tungsten-halogen units (QTH) were evaluated. Ceramic IPS e.max CAD shades A1, A2, A3, A3.5, high (HT) and low (LT) translucency were cut (1, 2, 3, 4 and 5 mm). Light sources emission spectra were determined. Light intensity incident and transmitted through each ceramic sample was measured to determine light transmission percentage (TP). Statistical analysis used a linear regression model. There was significant interaction between light source and ceramic translucency (p=0.008) and strong negative correlation (R=-0.845, pceramic thickness and TP. Increasing one unit in thickness led to 3.17 reduction in TP. There was no significant difference in TP (p=0.124) between shades A1 (ß1=0) and A2 (ß1=-0.45) but significant reduction occurred for A3 (ß1=-0.83) and A3.5 (ß1=-2.18). The interaction QTH/HT provided higher TP (ß1=0) than LED/HT (ß1=-2.92), QTH/LT (ß1=-3.75) and LED/LT (ß1=-5.58). Light transmission was more effective using halogen source and high-translucency ceramics, decreased as the ceramic thickness increased and was higher for the lighter shades, A1 and A2. From the regression model (R2=0.85), an equation was obtained to estimate TP value using each variable ß1 found. A maximum TP of 25% for QTH and 20% for LED was found, suggesting that ceramic light attenuation could compromise light cured and dual cure resin cements polymerization.

Murein Hydrolase Activity in the Surface Layer of Lactobacillus acidophilus ATCC 4356▿

OpenAIRE

Prado Acosta, Mariano; Palomino, María Mercedes; Allievi, Mariana C.; Rivas, Carmen Sanchez; Ruzal, Sandra M.

2008-01-01

We describe a new enzymatic functionality for the surface layer (S-layer) of Lactobacillus acidophilus ATCC 4356, namely, an endopeptidase activity against the cell wall of Salmonella enterica serovar Newport, assayed via zymograms and identified by Western blotting. Based on amino acid sequence comparisons, the hydrolase activity was predicted to be located at the C terminus. Subsequent cloning and expression of the C-terminal domain in Bacillus subtilis resulted in the functional verificati...

Discovery, SAR, and Radiolabeling of Halogenated Benzimidazole Carboxamide Antagonists as Useful Tools for (alpha)4(beta)1 Integrin Expressed on T- and B-cell Lymphomas

Energy Technology Data Exchange (ETDEWEB)

Carpenter, R D; Natarajan, A; Lau, E Y; Andrei, M; Solano, D M; Lightstone, F C; DeNardo, S J; Lam, K S; Kurth, M J

2010-02-08

The cell surface receptor {alpha}{sub 4}{beta}{sub 1} integrin is an attractive yet poorly understood target for selective diagnosis and treatment of T- and B-cell lymphomas. This report focuses on the rapid microwave preparation of medicinally pertinent benzimidazole heterocycles, structure-activity relationships (SAR) of novel halobenzimidazole carboxamide antagonists 3-6, and preliminary biological evaluation of radioiodinated agents 7, 8, and 18. The I-125 derivative 18 had good tumor uptake (12 {+-} 1% ID/g at 24 h; 4.5 {+-} 1% ID/g at 48 h) and tumor:kidney ratio ({approx}4:1 at 24 h; 2.5:1 at 48 h) in xenograft murine models of B-cell lymphoma. Molecular homology models of {alpha}{sub 4}{beta}{sub 1} integrin have predicted that docked halobenzimidazole carboxamides have the halogen atom in a suitable orientation for halogen-hydrogen bonding. These high affinity ({approx} pM binding) halogenated ligands are attractive tools for medicinal and biological use; the fluoro and iodo derivatives are potential radiodiagnostic ({sup 18}F) or radiotherapeutic ({sup 131}I) agents, whereas the chloro and bromo analogues could provide structural insight into integrin-ligand interactions through photoaffinity cross-linking/mass spectroscopy experiments, as well as co-crystallization X-ray studies.

Self-trapped holes in alkali silver halide crystals

International Nuclear Information System (INIS)

Awano, T.; Ikezawa, M.; Matsuyama, T.

1995-01-01

γ-Ray irradiation at 77 K induces defects in M 2 AgX 3 (M=Rb, K and NH 4 ; X=Br and I) crystals. The irradiation induces self-trapped holes of the form of I 0 in the case of alkali silver iodides, and (halogen) 2 - and (halogen) 0 in the case of ammonium silver halides. The (halogen) 0 is weakly coupled with the nearest alkali metal ion or ammonium ion. It is able to be denoted as RbI + , KI + , NH 4 I + or NH 4 Br + . The directions of hole distribution of (halogen) 2 - and (halogen) 0 were different in each case of the alkali silver iodides, ammonium silver halides and mixed crystal of them. The (halogen) 0 decayed at 160 K in annealing process. The (halogen) 2 - was converted into another form of (halogen) 2 - at 250 K and this decayed at 310 K. A formation of metallic layers was observed on the crystal surface parallel with the c-plane of (NH 4 ) 2 AgI 3 irradiated at room temperature. (author)

Elemental analysis of halogens using molecular emission by laser-induced breakdown spectroscopy in air

Energy Technology Data Exchange (ETDEWEB)

Gaft, M.; Nagli, L.; Eliezer, N.; Groisman, Y. [Laser Distance Spectrometry, 9 Mota Gur St., Petah Tikva 49514 (Israel); Forni, O. [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); CNRS, IRAP, 9 Av. Colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France)

2014-08-01

Fluorine and chlorine do not produce atomic and ionic line spectra of sufficient intensity to permit their detection by laser-induced breakdown spectroscopy. They do, however, combine with alkali-earths and other elements to form molecules whose spectra may be easily identified, enabling detection in ambient conditions with much higher sensitivity than using F I and Cl I atomic lines. - Highlights: • We studied laser induced breakdown spectra of halogens with alkali-earth elements. • Emission and temporal behavior of CaF and CaCl molecules were determined. • Sensitivity of F and Cl detection by molecules and atoms was compared.

Synthesis of α-Bromine- Terminated Polystyrene Macroinitiator and Its Initiation of MMA Polymerization by ATRP

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

In the present paper the synthesis of block copolymers via the transformation from living anionic polymerization (LAP) to atom transfer radical polymerization (ATRP) was described. Α-Bromine-terminated polystyrenes(PStBr) in the LAP step was prepared by using n-BuLi as initiator, tetrahydrofuran (THF) as the activator, α-methylstyrene (α-MeSt) as the capping group and liquid bromine (Br2) as the bromating agent. The effects of reaction conditions such as the amounts of α-MeSt, THF, and Br2 as well as molecular weight of polystyrene on the bromating efficiency (BE) and coupling extent (CE) were examined. The present results show that the yield of PStBr obtained was more than 93.8% and the coupling reaction was substantially absent. PStBr was further used as the macroinitiator in the polymerization of methyl-methacrylate(MMA) in the presence of copper(Ⅰ) halogen and 2,2-bipyridine(bpy) complexes. It was found that the molecular weight of the resulted PSt-b-PMMA increased linearly with the increase of the conversion of MMA and the polydispersity was 1.2-1.6. The structures of PStBr and P(St-b-MMA) were characterized by 1H NMR spectra.

Removal of halogenated organic compounds in landfill gas by top covers containing zero-valent iron

DEFF Research Database (Denmark)

Scheutz, Charlotte; Winther, K.; Kjeldsen, Peter

2000-01-01

Transformation of gaseous CCl3F and CCl4 by zero-valent iron was studied in systems unsaturated with water under anaerobic conditionssin an N2 gas and in a landfill gas atmosphere. The transformation was studied in batch as well as flow-through column tests. In both systems, the transformation....... During continuous aerobic conditions, the transformation of CCl3F decreased toward zero. Model calculations show that use of zero-valent iron in landfill top covers is a potential treatment technology for emission reduction of halogenated trace compounds from landfills....

Enlargement of Axo-Somatic Contacts Formed by GAD-Immunoreactive Axon Terminals onto Layer V Pyramidal Neurons in the Medial Prefrontal Cortex of Adolescent Female Mice Is Associated with Suppression of Food Restriction-Evoked Hyperactivity and Resilience to Activity-Based Anorexia

OpenAIRE

Chen, Yi-Wen; Wable, Gauri Satish; Chowdhury, Tara Gunkali; Aoki, Chiye

2015-01-01

Many, but not all, adolescent female mice that are exposed to a running wheel while food restricted (FR) become excessive wheel runners, choosing to run even during the hours of food availability, to the point of death. This phenomenon is called activity-based anorexia (ABA). We used electron microscopic immunocytochemistry to ask whether individual differences in ABA resilience may correlate with the lengths of axo-somatic contacts made by GABAergic axon terminals onto layer 5 pyramidal neur...

Local layer structure of smectic liquid crystals by X-ray micro-diffraction

CERN Document Server

Takanishi, Y

2003-01-01

The local layer structure of smectic liquid crystal has been measured using time-resolved synchrotron X-ray micro-diffraction. Typical layer disorders observed in surface stabilized (anti-) ferroelectric liquid crystals, i.e. a stripe texture, a needed-like defect and a zigzag defect, are directly analyzed. The detailed analysis slows that the surface anchoring force due to the interaction between the liquid crystal molecule and the alignment thin film plays an important role to realize both the static and dynamic local layer structures. The layer structure of the circular domain observed in the liquid crystal of bent-shaped molecules found to depend on the applied electric field though the optical micrograph shows little difference. The frustrated, double and single layer structures of the bent-shaped molecule liquid crystal are determined depending on the terminal alkyl chain length. (author)

Hydrogen-terminated diamond vertical-type metal oxide semiconductor field-effect transistors with a trench gate

Energy Technology Data Exchange (ETDEWEB)

Inaba, Masafumi, E-mail: inaba-ma@ruri.waseda.jp; Muta, Tsubasa; Kobayashi, Mikinori; Saito, Toshiki; Shibata, Masanobu; Matsumura, Daisuke; Kudo, Takuya; Hiraiwa, Atsushi [Graduate School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Kawarada, Hiroshi [Graduate School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku, Tokyo 169-0051 (Japan)

2016-07-18

The hydrogen-terminated diamond surface (C-H diamond) has a two-dimensional hole gas (2DHG) layer independent of the crystal orientation. A 2DHG layer is ubiquitously formed on the C-H diamond surface covered by atomic-layer-deposited-Al{sub 2}O{sub 3}. Using Al{sub 2}O{sub 3} as a gate oxide, C-H diamond metal oxide semiconductor field-effect transistors (MOSFETs) operate in a trench gate structure where the diamond side-wall acts as a channel. MOSFETs with a side-wall channel exhibit equivalent performance to the lateral C-H diamond MOSFET without a side-wall channel. Here, a vertical-type MOSFET with a drain on the bottom is demonstrated in diamond with channel current modulation by the gate and pinch off.

Nonleaking battery terminals.

Science.gov (United States)

Snider, W. E.; Nagle, W. J.

1972-01-01

Three different terminals were designed for usage in a 40 ampere/hour silver zinc battery which has a 45% KOH by weight electrolyte in a plastic battery case. Life tests, including thermal cycling, electrical charge and discharge for up to three years duration, were conducted on these three different terminal designs. Tests for creep rate and tensile strength were conducted on the polyphenylene oxide plastic battery cases. Some cases were unused and others containing KOH electrolyte were placed on life tests. The design and testing of nonleaking battery terminals for use with a KOH electrolyte in a plastic case are considered.

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).

Bis(tetraphenylphosphonium di-μ-iodido-bis[diiodidotellurate(II

Directory of Open Access Journals (Sweden)

Risto S. Laitinen

2008-12-01

Full Text Available The structure of the title compound, (C24H20P2[Te2I6], is composed of discrete PPh4+ cations and centrosymmetric [Te2I6]2− anions. The tellurium(II atom shows a sligthly distorted square-planar TeI4 geometry and is coordinated to two bridging and two terminal iodine atoms. The planar [Te2I6]2− ions are isolated by the cations and no intermolecular tellurium–halogen or halogen–halogen interactions are present.

Potential barrier heights at metal on oxygen-terminated diamond interfaces

Energy Technology Data Exchange (ETDEWEB)

Muret, P., E-mail: pierre.muret@neel.cnrs.fr; Traoré, A.; Maréchal, A.; Eon, D. [Inst. NEEL, Univ. Grenoble Alpes, F-38042 Grenoble, France and CNRS, Inst. NEEL, F-38042 Grenoble (France); Pernot, J. [Univ. Grenoble Alpes, Inst. NEEL, F-38042 Grenoble, (France); CNRS, Inst. NEEL, F-38042 Grenoble, (France); Institut Universitaire de France, 103 Boulevard Saint-Michel, F-75005 Paris (France); Pinero, J. C.; Villar, M. P.; Araujo, D., E-mail: daniel.araujo@uca.es [Dpto. Ciencias de los Materiales, Universidad de Cádiz, 11510 Puerto Real (Cádiz) (Spain)

2015-11-28

Electrical properties of metal-semiconductor (M/SC) and metal/oxide/SC structures built with Zr or ZrO{sub 2} deposited on oxygen-terminated surfaces of (001)-oriented diamond films, comprised of a stack of lightly p-doped diamond on a heavily doped layer itself homoepitaxially grown on an Ib substrate, are investigated experimentally and compared to different models. In Schottky barrier diodes, the interfacial oxide layer evidenced by high resolution transmission electron microscopy and electron energy losses spectroscopy before and after annealing, and barrier height inhomogeneities accounts for the measured electrical characteristics until flat bands are reached, in accordance with a model which generalizes that by Tung [Phys. Rev. B 45, 13509 (1992)] and permits to extract physically meaningful parameters of the three kinds of interface: (a) unannealed ones, (b) annealed at 350 °C, (c) annealed at 450 °C with the characteristic barrier heights of 2.2–2.5 V in case (a) while as low as 0.96 V in case (c). Possible models of potential barriers for several metals deposited on well defined oxygen-terminated diamond surfaces are discussed and compared to experimental data. It is concluded that interface dipoles of several kinds present at these compound interfaces and their chemical evolution due to annealing are the suitable ingredients that are able to account for the Mott-Schottky behavior when the effect of the metal work function is ignored, and to justify the reverted slope observed regarding metal work function, in contrast to the trend always reported for all other metal-semiconductor interfaces.

Unidirectional spin Hall magnetoresistance in topological insulator/ferromagnetic layer heterostructures

Science.gov (United States)

Kally, James; Lv, Yang; Zhang, Delin; Lee, Joon Sue; Samarth, Nitin; Wang, Jian-Ping; Department of Electrical; Computer Engineering, University of Minnesota, Minneapolis Collaboration; Department of Physics, Pennsylvania State University Collaboration

The surface states of topological insulators offer a potentially very efficient way to generate spins and spin-orbit torques to magnetic moments in proximity. The switching by spin-orbit torque itself only requires two terminals so that a charge current can be applied. However, a third terminal with additional magnetic tunneling junction structure is needed to sense the magnetization state if such devices are used for memory and logic applications. The recent discovery of unidirectional spin Hall magnetoresistance in heavy metal/ferromagnetic and topological insulator/magnetically doped topological insulator systems offers an alternative way to sense magnetization while still keeping the number of terminals to minimal two. The unidirectional spin Hall magnetoresistance in topological insulator/strong ferromagnetic layer heterostructure system has yet not been reported. In this work, we report our experimental observations of such magnetoresistance. It is found to be present and comparable to the best result of the previous reported Ta/Co systems in terms of magnetoresistance per current density per total resistance.

Topotactic condensation of layer silicates with ferrierite-type layers forming porous tectosilicates.

Science.gov (United States)

Marler, B; Wang, Y; Song, J; Gies, H

2014-07-21

Five different hydrous layer silicates (HLSs) containing fer layers (ferrierite-type layers) were obtained by hydrothermal syntheses from mixtures of silicic acid, water and tetraalkylammonium/tetraalkylphosphonium hydroxides. The organic cations had been added as structure directing agents (SDA). A characteristic feature of the structures is the presence of strong to medium strong hydrogen bonds between the terminal silanol/siloxy groups of neighbouring layers. The five-layered silicates differ chemically only with respect to the organic cations. Structurally, they differ with respect to the arrangement of the fer layers relative to each other, which is distinct for every SDA-fer-layer system. RUB-20 (containing tetramethylammonium) and RUB-40 (tetramethylphosphonium) are monoclinic with stacking sequence AAA and shift vectors between successive layers 1a0 + 0b0 + 0.19c0 and 1a0 + 0b0 + 0.24c0, respectively. RUB-36 (diethyldimethylammonium), RUB-38 (methyltriethylammonium) and RUB-48 (trimethylisopropylammonium) are orthorhombic with stacking sequence ABAB and shift vectors 0.5a0 + 0b0± 0.36c0, 0.5a0 + 0b0 + 0.5c0 and 0.5a0 + 0b0± 0.39c0, respectively. Unprecedented among the HLSs, two monoclinic materials are made up of fer layers which possess a significant amount of ordered defects within the layer. The ordered defects involve one particular Si-O-Si bridge which is, to a fraction of ca. 50%, hydrolyzed to form nests of two ≡Si-OH groups. When heated to 500-600 °C in air, the HLSs condense to form framework silicates. Although all layered precursors were moderately to well ordered, the resulting framework structures were of quite different crystallinity. The orthorhombic materials RUB-36, -38 and -48, general formula SDA4Si36O72(OH)4, which possess very strong hydrogen bonds (d[O···O] ≈ 2.4 Å), transform into a fairly or well ordered CDO-type silica zeolite RUB-37. The monoclinic materials RUB-20 and -40, general formula SDA2Si18O36(OH)2OH, possessing

Chemical vapour transport of pyrite (FeS 2) with halogen (Cl, Br, I)

Science.gov (United States)

Fiechter, S.; Mai, J.; Ennaoui, A.; Szacki, W.

1986-12-01

A systematic study of chemical vapour transport (CVT) of pyrite with halogen, hydrogen halides and ammonium halides as transporting agents has shown that the transport with chlorine and bromine in a temperature gradient Δ T = 920-820 K yields the highest transport rates (˜6 mg/h) with crystals up to 5 mm edge length. Computing thermochemical equilibria and flux functions in the system Fe-S-Hal (Hal = Cl, Br, I) it has been confirmed that the transport velocity of pyrite is limited by the concentration of FeHal 2 in the vapour phase, the equilibrium position between FeHal 2(g) and FeHal 3(g) and the flux directions of the iron gas species.

Intrinsic terminators in Mycoplasma hyopneumoniae transcription.

Science.gov (United States)

Fritsch, Tiago Ebert; Siqueira, Franciele Maboni; Schrank, Irene Silveira

2015-04-08

Mycoplasma hyopneumoniae, an important pathogen of swine, exhibits a low guanine and cytosine (GC) content genome. M. hyopneumoniae genome is organised in long transcriptional units and promoter sequences have been mapped upstream of all transcription units. These analysis provided insights into the gene organisation and transcription initiation at the genome scale. However, the presence of transcriptional terminator sequences in the M. hyopneumoniae genome is poorly understood. In silico analyses demonstrated the presence of putative terminators in 82% of the 33 monocistronic units (mCs) and in 74% of the 116 polycistronic units (pCs) considering different classes of terminators. The functional activity of 23 intrinsic terminators was confirmed by RT-PCR and qPCR. Analysis of all terminators found by three software algorithms, combined with experimental results, allowed us to propose a pattern of RNA hairpin formation during the termination process and to predict the location of terminators in the M. hyopneumoniae genome sequence. The stem-loop structures of intrinsic terminators of mycoplasma diverge from the pattern of terminators found in other bacteria due the low content of guanine and cytosine. In M. hyopneumoniae, transcription can end after a transcriptional unit and before its terminator sequence and can also continue past the terminator sequence with RNA polymerases gradually releasing the RNA.

Halogenated furanones from the red alga, Delisea pulchra, inhibit carbapenem antibiotic synthesis and exoenzyme virulence factor production in the phytopathogen Erwinia carotovora

DEFF Research Database (Denmark)

Manefield, M.; Welch, M.; Givskov, Michael Christian

2001-01-01

The plant pathogen Erwinia carotovora regulates expression of virulence factors and antibiotic production via an N-3- oxohexanoyl-L-homoserine lactone (3-oxo-C6-HSL) dependent quorum sensing mechanism. The marine alga Delisea pulchra produces halogenated furanones known to antagonise 3-oxo-C6-HSL...

First-principles studies for the stability of a graphene-like boron layer on CrB2(0001) and MoB2(0001)

International Nuclear Information System (INIS)

Qin Na; Liu Shiyu; Li Zhen; Zhao Hui; Wang Sanwu

2011-01-01

With extensive first-principles density-functional-theory calculations, we investigate the stability and the atomic and electronic structures of the CrB 2 (0001) and MoB 2 (0001) surfaces, each with two different terminations. It is found that the boron-terminated surface is energetically more favorable over the wide range of thermodynamically allowed chemical potentials than the metal-terminated surface for both CrB 2 (0001) and MoB 2 (0001), suggesting a stable layer of graphene-like boron on the surfaces. Our results also show the similarities and the differences in relaxation and in bonding characteristics between the boron-terminated and metal-terminated surfaces.

INAA applied to halogen (Br and I) stability in long-term storage of lyophilized biological materials

International Nuclear Information System (INIS)

Zaichick, V.; Zaichick, S.

2000-01-01

Instrumental neutron activation analysis (INAA) was used to determine the Br and I concentration in the same ten lyophilized and homogenized human thyroid samples prior and after a 20-year storage at room temperature. It was found that long-term storage had no effect on the iodine content. At the same time, the bromine content was about 2-fold lower (p<0.01). It was assumed that possible losses of other halogens can occur under long-term storage of lyophilized biological materials at room temperature. (author)

Investigation of the surface terminations of icosahedral AlPdMn quasicrystal based on a modified non-spherical model

International Nuclear Information System (INIS)

Yu Fengmei; Zou Huamin; Wang Jianbo; Wang Renhui

2004-01-01

The atomic positions are obtained from a modified non-spherical model of icosahedral AlPdMn quasicrystal (Fang et al 2003 J. Phys.: Condens. Matter 15 4947) by the cut method. The four-shell pseudo-Mackay clusters (PMCs) were searched for in a box of 400 A x 400 A x 400 A. The results show that the number of atoms in the fourth shell, an icosidodecahedron, of the pseudo-Mackay cluster can vary from 15 to 30 because of the cluster overlap, and about 99.96% of the total atoms are included in such incomplete pseudo-Mackay clusters. The characteristics of the atom distribution in the planes perpendicular to a fivefold axis indicate that the planes, which are 1.56 A apart from their neighbouring planes, are expected to be the terminal surfaces. If one such a plane and its closest neighbouring plane, between which the spacing is 0.48 A, are considered as a thin layer or a corrugated surface, these layers are also the layers with the maximum density. The pair of corrugated surfaces that are 1.56 A apart have almost identical chemical composition. These planes form terraces that follow the rule of the Fibonacci sequence with two step heights, 6.60 and 4.08 A. On the corrugated surfaces perpendicular to a fivefold axis the pentagonal holes arise from the interspaces of adjacent incomplete PMCs. For the atomic planes normal to a twofold axis, the planes with spacing of 1.48 A from their adjacent planes might be expected to be the terminal surfaces, which form terraces with step heights of 6.28 and 3.88 A following the rule of the Fibonacci sequence. For the atomic planes normal to a threefold axis, the planes with spacing of 0.86 A from their adjacent planes might be expected to be the terminal surfaces. No similar results were found for the atomic layers perpendicular to a pseudo-twofold axis

Modulation of human α4β2 nicotinic acetylcholine receptors by brominated and halogen-free flame retardants as a measure for in vitro neurotoxicity

NARCIS (Netherlands)

Hendriks, H.S.; van Kleef, R.G.D.M.; Westerink, R.H.S.

2012-01-01

Brominated flame retardants (BFRs) are abundant persistent organic pollutants with well-studied toxicity. The toxicological and ecological concern associated with BFRs argues for replacement by safer alternatives. However, the (neuro)toxic potential of alternative halogen-free flame retardants

Termination unit

Energy Technology Data Exchange (ETDEWEB)

Traeholt, Chresten; Willen, Dag; Roden, Mark; Tolbert, Jerry C.; Lindsay, David; Fisher, Paul W.; Nielsen, Carsten Thidemann

2016-05-03

Cable end section comprises end-parts of N electrical phases/neutral, and a thermally-insulation envelope comprising cooling fluid. The end-parts each comprises a conductor and are arranged with phase 1 innermost, N outermost surrounded by the neutral, electrical insulation being between phases and N and neutral. The end-parts comprise contacting surfaces located sequentially along the longitudinal extension of the end-section. A termination unit has an insulating envelope connected to a cryostat, special parts at both ends comprising an adapter piece at the cable interface and a closing end-piece terminating the envelope in the end-section. The special parts houses an inlet and/or outlet for cooling fluid. The space between an inner wall of the envelope and a central opening of the cable is filled with cooling fluid. The special part at the end connecting to the cryostat houses an inlet or outlet, splitting cooling flow into cable annular flow and termination annular flow.

Atomic forces between noble gas atoms, alkali ions, and halogen ions for surface interactions

Science.gov (United States)

Wilson, J. W.; Outlaw, R. A.; Heinbockel, J. H.

1988-01-01

The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base developed from analysis of the two-body potential data, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas surfaces and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

Quantitative structure-activity relationships for toxicity and genotoxicity of halogenated aliphatic compounds: wing spot test of Drosophila melanogaster.

Science.gov (United States)

Chroust, Karel; Pavlová, Martina; Prokop, Zbynek; Mendel, Jan; Bozková, Katerina; Kubát, Zdenek; Zajícková, Veronika; Damborský, Jiri

2007-02-01

Halogenated aliphatic compounds were evaluated for toxic and genotoxic effects in the somatic mutation and recombination test employing Drosophila melanogaster. The tested chemicals included chlorinated, brominated and iodinated; mono-, di- and tri-substituted; saturated and unsaturated alkanes: 1,2-dibromoethane, 1-bromo-2-chloroethane, 1-iodopropane, 2,3-dichloropropene, 3-bromo-1-propene, epibromohydrin, 2-iodobutane, 3-chloro-2-methylpropene, 1,2,3-trichloropropane, 1,2-dichloroethane, 1,2-dichlorobutane, 1-chloro-2-methylpropane, 1,3-dichloropropane, 1,2-dichloropropane, 2-chloroethymethylether, 1-bromo-2-methylpropane and 1-chloropentane. N-methyl-N-nitrosourea served as the positive and distilled water as the negative control. The set of chemicals for the toxicological testing was selected by the use of statistical experiment design. Group of unsaturated aliphatic hydrocarbons were generally more toxic than saturated analogues. The genotoxic effect was observed with 14 compounds in the wing spot test, while 3 substances did not show any genotoxicity by using the wing spot test at 50% lethal concentration. The highest number of wing spots was observed in genotoxicity assay with 1-bromo-2-chloroethane, 1,2-dichloroethane, 1,2-dibromoethane and 1-iodopropane. Nucleophilic superdelocalizability calculated by quantum mechanics appears to be a good parameter for prediction of both toxicity and genotoxicity effects of halogenated aliphatic compounds.

Impact of Nitrification on the Formation of N-Nitrosamines and Halogenated Disinfection Byproducts within Distribution System Storage Facilities.

Science.gov (United States)

Zeng, Teng; Mitch, William A

2016-03-15

Distribution system storage facilities are a critical, yet often overlooked, component of the urban water infrastructure. This study showed elevated concentrations of N-nitrosodimethylamine (NDMA), total N-nitrosamines (TONO), regulated trihalomethanes (THMs) and haloacetic acids (HAAs), 1,1-dichloropropanone (1,1-DCP), trichloroacetaldehyde (TCAL), haloacetonitriles (HANs), and haloacetamides (HAMs) in waters with ongoing nitrification as compared to non-nitrifying waters in storage facilities within five different chloraminated drinking water distribution systems. The concentrations of NDMA, TONO, HANs, and HAMs in the nitrifying waters further increased upon application of simulated distribution system chloramination. The addition of a nitrifying biofilm sample collected from a nitrifying facility to its non-nitrifying influent water led to increases in N-nitrosamine and halogenated DBP formation, suggesting the release of precursors from nitrifying biofilms. Periodic treatment of two nitrifying facilities with breakpoint chlorination (BPC) temporarily suppressed nitrification and reduced precursor levels for N-nitrosamines, HANs, and HAMs, as reflected by lower concentrations of these DBPs measured after re-establishment of a chloramine residual within the facilities than prior to the BPC treatment. However, BPC promoted the formation of halogenated DBPs while a free chlorine residual was maintained. Strategies that minimize application of free chlorine while preventing nitrification are needed to control DBP precursor release in storage facilities.

Novel enhancement of thin-form-factor galvanic cells: Probing halogenated organic oxidizers and metal anodes

Energy Technology Data Exchange (ETDEWEB)

Cardenas-Valencia, Andres M.; Adornato, Lori; Short, R. Timothy; Langebrake, Larry [SRI International, Engineering and Systems Division, Marine Technology Program, 140 Seventh Avenue South, St Petersburg, FL 33701 (United States)

2008-09-15

The work reported herein demonstrates a novel method to improve the overall performance of thin-form-factor galvanic cells, fabricated via micro-electromechanical systems (MEMS) processes. Use of solid, low cost, cyclic-halogenated, organic catholyte materials permits water activation of cells consisting of metal anode and catalytic platinum positive electrodes. Similar cells, employing aluminum and zinc anodes, have been activated using sodium hypochlorite (NaClO) solutions, i.e. bleach, in the past. The oxidizers chosen for this study (bromo-, chloro- and iodo-succinimides, and sodium dichloroisocyanuric acid) supply the cathode's oxy-halogenated ions when in contact with water. Zinc, magnesium and aluminum anodes are utilized to fabricate galvanic cells. A comparison between these anodes, coupled with various oxidizers, is included herein. Results using aluminum anode cells show that, even though the utilization efficiency of the catholyte reagents is low (faradic efficiencies between 16 and 19%), the performance of the new water-activated cells (6 cm x 6 cm x 0.25 cm) is superior when compared to those activated with bleach. For instance, operational lives of 6 h (activation with 10% NaClO solution) increase to more than 30 h using the new approach, with a 100-ohm-load. It is also shown that specific energies of 90-110 Wh kg{sup -1} (calculated to include both reagent and packaging mass) could be obtained using the described approach with current draws between 10 and 20 mA. The specific energies obtained suggest that novel MEMS-type cells could have much broader application than low-current, bleach-activated cells. (author)

Sea ice dynamics influence halogen deposition to Svalbard

Directory of Open Access Journals (Sweden)

A. Spolaor

2013-10-01

Full Text Available Sea ice is an important parameter in the climate system and its changes impact upon the polar albedo and atmospheric and oceanic circulation. Iodine (I and bromine (Br have been measured in a shallow firn core drilled at the summit of the Holtedahlfonna glacier (Northwest Spitsbergen, Svalbard. Changing I concentrations can be linked to the March–May maximum sea ice extension. Bromine enrichment, indexed to the Br / Na sea water mass ratio, appears to be influenced by changes in the seasonal sea ice area. I is emitted from marine biota and so the retreat of March–May sea ice coincides with enlargement of the open-ocean surface which enhances marine primary production and consequent I emission. The observed Br enrichment could be explained by greater Br emissions during the Br explosions that have been observed to occur mainly above first year sea ice during the early springtime. In this work we present the first comparison between halogens in surface snow and Arctic sea ice extension. Although further investigation is required to characterize potential depositional and post-depositional processes, these preliminary findings suggest that I and Br can be linked to variability in the spring maximum sea ice extension and seasonal sea ice surface area.

Flaking of co-deposited hydrogenated carbon layers on the TFTR limiter

International Nuclear Information System (INIS)

Skinner, C.H.; Gentile, C.A.; Menon, M.M.; Barry, R.E.

1999-01-01

Flaking of co-deposited layers on the inner limiter tiles was recently observed in TFTR. This phenomenon was unexpected and has occurred since the termination of plasma operations on 4 April 1997. Flaking affects approximately 15% of the observable tiles and appears on isotropic graphite but not on carbon fibre composite tiles. Photographic images of the flakes and precise measurements of the limiter geometry are reported. The mobilizability of tritium retained in co-deposited layers is an important factor in safety analyses of future DT reactors. A programme to analyse the flakes and tiles is underway. (author). Letter-to-the-editor

Low cost, robust and real time system for detecting and tracking moving objects to automate cargo handling in port terminals

NARCIS (Netherlands)

Vaquero, V.; Repiso, E.; Sanfeliu, A.; Vissers, J.; Kwakkernaat, M.

2016-01-01

The presented paper addresses the problem of detecting and tracking moving objects for autonomous cargo handling in port terminals using a perception system which input data is a single layer laser scanner. A computationally low cost and robust Detection and Tracking Moving Objects (DATMO) algorithm

The kinetics of reductive dehalogenation of a set of halogenated aliphatic hydrocarbons in anaerobic sediment slurries.

Science.gov (United States)

Peijnenburg, W; Eriksson, L; de Groot, A; Sjöström, M; Verboom, H

1998-01-01

Disappearance rate constants are reported for the reductive transformation of 17 halogenated aliphatic hydrocarbons in anaerobic sediment-water samples. Statistical experimental design in combination with multivariate chemical characterization of their chemical properties was used to select the compounds. Degradation followed pseudo first-order kinetics through at least two half-lives for 15 of the 17 compounds. Of all the compounds investigated, 1,2,3-trichloropropane and dichloromethane were unique in that they were dehalogenated according to zero-order kinetics. Reductive dehalogenation was the sole transformation reaction taking place.

klax Terminal Aerodrome Forecast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — TAF (terminal aerodrome forecast or terminal area forecast) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are...

kprc Terminal Aerodrome Forecast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — TAF (terminal aerodrome forecast or terminal area forecast) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are...

katl Terminal Aerodrome Forecast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — TAF (terminal aerodrome forecast or terminal area forecast) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are...

kmcn Terminal Aerodrome Forecast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — TAF (terminal aerodrome forecast or terminal area forecast) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are...

kogb Terminal Aerodrome Forecast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — TAF (terminal aerodrome forecast or terminal area forecast) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are...

kama Terminal Aerodrome Forecast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — TAF (terminal aerodrome forecast or terminal area forecast) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are...

ptkk Terminal Aerodrome Forecast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — TAF (terminal aerodrome forecast or terminal area forecast) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are...

kiwa Terminal Aerodrome Forecast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — TAF (terminal aerodrome forecast or terminal area forecast) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are...

kavp Terminal Aerodrome Forecast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — TAF (terminal aerodrome forecast or terminal area forecast) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are...

kdca Terminal Aerodrome Forecast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — TAF (terminal aerodrome forecast or terminal area forecast) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are...

kbwg Terminal Aerodrome Forecast

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — TAF (terminal aerodrome forecast or terminal area forecast) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are...

kdfw Terminal Aerodrome Forecast