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Sample records for halogenated molecules adsorbed

  1. 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

  2. Simulations of the Static Friction Due to Adsorbed Molecules

    OpenAIRE

    He, Gang; Robbins, Mark O.

    2001-01-01

    The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent with macroscopic friction laws. Crystalline alignment, sliding direction, and the number of adsorbed molecules are not controlled in most experiments and are shown to have little effect on the friction. Temperature, molecular geometry and interaction potenti...

  3. 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

  4. 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.

  5. Hydrogen molecule on lithium adsorbed graphene: A DFT study

    International Nuclear Information System (INIS)

    Kaur, Gagandeep; Gupta, Shuchi; Gaganpreet; Dharamvir, Keya

    2016-01-01

    Electronic structure calculations for the adsorption of molecular hydrogen on lithium (Li) decorated and pristine graphene have been studied systematically using SIESTA code [1] within the framework of the first-principle DFT under the Perdew-Burke-Ernzerhof (PBE) form of the generalized gradient approximation (GGA)[2], including spin polarization. The energy of adsorption of hydrogen molecule on graphene is always enhanced by the presence of co-adsorbed lithium. The most efficient adsorption configuration is when H 2 is lying parallel to lithium adsorbed graphene which is in contrast to its adsorption on pristine graphene (PG) where it prefers perpendicular orientation.

  6. Scattering of atoms by molecules adsorbed at solid surfaces

    International Nuclear Information System (INIS)

    Parra, Zaida.

    1988-01-01

    The formalism of collisional time-correlation functions, appropriate for scattering by many-body targets, is implemented to study energy transfer in the scattering of atoms and ions from molecules adsorbed on metal surfaces. Double differential cross-sections for the energy and angular distributions of atoms and ions scattered by a molecule adsorbed on a metal surface are derived in the limit of impulsive collisions and within a statistical model that accounts for single and double collisions. They are found to be given by the product of an effective cross-section that accounts for the probability of deflection into a solid angle times a probability per unit energy transfer. A cluster model is introduced for the vibrations of an adsorbed molecule which includes the molecular atoms, the surface atoms binding the molecule, and their nearest neighbors. The vibrational modes of CO adsorbed on a Ni(001) metal surface are obtained using two different cluster models to represent the on-top and bridge-bonding situations. A He/OC-Ni(001) potential is constructed from a strongly repulsive potential of He interacting with the oxygen atom in the CO molecule and a van der Waals attraction accounting for the He interaction with the free Ni(001) surface. A potential is presented for the Li + /OC-Ni(001) where a coulombic term is introduced to account for the image force. Trajectory studies are performed and analyzed in three dimensions to obtain effective classical cross-sections for the He/OC-Ni(001) and Li + /OC-Ni(001) systems. Results for the double differential cross-sections are presented as functions of scattering angles, energy transfer and collisional energy. Temperature dependence results are also analyzed. Extensions of the approach and inclusion of effects such as anharmonicity, collisions at lower energies, and applications of the approach to higher coverages are discussed

  7. Bibliography of electron and photon cross sections with atoms and molecules published in the 20th century. Halogen molecules

    International Nuclear Information System (INIS)

    Hayashi, Makoto

    2003-12-01

    A bibliographies of original and review reports of experiments or theories of electron and photon cross sections and also electron swarm data are presented for atomic or molecular species with specified targets. These works covered 17 atoms and 51 molecules. The present bibliography is only for halogen molecules (F 2 , Cl 2 , Br 2 , I 2 ). About 190(F 2 ), 360(Cl 2 ), 140(Br 2 ) and 240(I 2 ) papers were compiled respectively. A comprehensive author indexes for each molecule are included. The bibliography covers the period 1901 through 2000 for F 2 -I 2 . Finally, author's comments for F 2 -I 2 electron collision cross sections are given. (author)

  8. Molecular Beam Chemistry: Reactions of Oxygen Atoms with Halogen Molecules.

    Science.gov (United States)

    1982-10-15

    nonlinear one has s = 3, r = 1, and n = 3/2. In the "loose" complex the bending modes go over to free rotation of the product diatomit molecule; thus s...contains no adjustable parameters. All observable properties *l of the reaction may be predicted including product velocity and angular dis- tributions...example, P. R. Bevington, Data Reduction and Error Analysis for the Physical Sciences (McGraw-Hill Book Co., New York, 1969). 65. Equation (3) is strictly

  9. 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.

  10. Determination of adsorbable organic halogens in surface water samples by combustion-microcoulometry versus combustion-ion chromatography titration.

    Science.gov (United States)

    Kinani, Aziz; Sa Lhi, Hacène; Bouchonnet, Stéphane; Kinani, Said

    2018-03-02

    Adsorbable Organic Halogen (AOX) is an analytical parameter of considerable interest since it allows to evaluate the amount of organohalogen disinfection by-products (OXBPs) present in a water sample. Halogen speciation of AOX into adsorbable organic chlorine, bromine and iodine, respectively AOCl, AOBr and AOI, is extremely important since it has been shown that iodinated and brominated organic by-products tend to be more toxic than their chlorinated analogues. Chemical speciation of AOX can be performed by combustion-ion chromatography (C-IC). In the present work, the effectiveness of the nitrate wash according to ISO 9562 standard method protocol to eliminate halide ions interferences was firstly examined. False positive AOX values were observed when chloride concentration exceeded 100 ppm. The improvements made to the washing protocol have eliminated chloride interference for concentrations up to 1000 ppm. A C-IC method for chemical speciation of AOX into AOCl, AOBr, and AOI has been developed and validated. The most important analytical parameters were investigated. The following optimal conditions were established: an aqueous solution containing 2.4 mM sodium bicarbonate/2.0 mM sodium carbonate, and 2% acetone (v/v) as mobile phase, 2 mL of aqueous sodium thiosulfate (500 ppm) as absorption solution, 0.2 mL min -1 as water inlet flow rate for hydropyrolysis, and 10 min as post-combustion time. The method was validated according to NF T90-210 standard method. Calibration curves fitted through a quadratic equation show coefficients of determination (r 2 ) greater than 0.9998, and RSD less than 5%. The LOQs were 0.9, 4.3, and 5.7 μg L -1 Cl for AOCl, AOBr, and AOI, respectively. The accuracy, in terms of relative error, was within a ± 10% interval. The applicability of the validated method was demonstrated by the analysis of twenty four water samples from three rivers in France. The measurements reveals AOX amounts above 10

  11. Core Level Spectra of Organic Molecules Adsorbed on Graphene

    Directory of Open Access Journals (Sweden)

    Abhilash Ravikumar

    2018-03-01

    Full Text Available We perform first principle calculations based on density functional theory to investigate the effect of the adsorption of core-excited organic molecules on graphene. We simulate Near Edge X-ray absorption Fine Structure (NEXAFS and X-ray Photoemission Spectroscopy (XPS at the N and C edges for two moieties: pyridine and the pyridine radical on graphene, which exemplify two different adsorption characters. The modifications of molecular and graphene energy levels due to their interplay with the core-level excitation are discussed. We find that upon physisorption of pyridine, the binding energies of graphene close to the adsorption site reduce mildly, and the NEXAFS spectra of the molecule and graphene resemble those of gas phase pyridine and pristine graphene, respectively. However, the chemisorption of the pyridine radical is found to significantly alter these core excited spectra. The C 1s binding energy of the C atom of graphene participating in chemisorption increases by ∼1 eV, and the C atoms of graphene alternate to the adsorption site show a reduction in the binding energy. Analogously, these C atoms also show strong modifications in the NEXAFS spectra. The NEXAFS spectrum of the chemisorbed molecule is also modified as a result of hybridization with and screening by graphene. We eventually explore the electronic properties and magnetism of the system as a core-level excitation is adiabatically switched on.

  12. Vibrational properties of water molecules adsorbed in different zeolitic frameworks

    International Nuclear Information System (INIS)

    Crupi, V; Longo, F; Majolino, D; Venuti, V

    2006-01-01

    The perturbation of water 'sorbed' in samples of zeolites of different structural type, genesis, and cation composition (K-, Na-, Mg- and Ca-rich zeolites), namely the CHA framework of a synthetic K-chabazite, the LTA framework of synthetic Na-A and Mg50-A zeolites, and the NAT framework of a natural scolecite, has been studied by FTIR-ATR spectroscopy, in the -10 to +80 o C temperature range. The aim was to show how differences in the chemical composition and/or in the topology of the zeolite framework and, in particular, the possibility for the guest water molecules to develop guest-guest and/or host-guest interactions, lead to substantial differences in their vibrational dynamical properties. The spectra, collected in the O-H stretching and H 2 O bending mode regions, are complex, with multiple bands being observed. As far as water in the CHA and LTA frameworks is concerned, whose behaviour is governed by the balance of water-water, water-framework and water-extra-framework cations interactions, the assignment of the resolved components of the O-H stretching band has been discussed by fitting the band shapes into individual components attributed to H 2 O molecules engaged in different degrees of hydrogen bonding. A detailed quantitative picture of the connectivity pattern of water, as a function of temperature and according to the chemical and topological properties of the environment, is furnished. The H 2 O bending vibrational bands give additional information that perfectly agrees with the results obtained from the analysis of the O-H stretching spectral region. In the case of scolecite, a small-pored zeolite where water-water interactions are eliminated, the increased complexity observed in the infrared spectra in the O-H stretching and H 2 O bending regions was explained as due to the hydrogen bonding between the water molecules and the network, and also with the extra-framework cation. Furthermore, these observations have been correlated with the different

  13. Nanospectroscopy of thiacyanine dye molecules adsorbed on silver nanoparticle clusters

    Science.gov (United States)

    Ralević, Uroš; Isić, Goran; Anicijević, Dragana Vasić; Laban, Bojana; Bogdanović, Una; Lazović, Vladimir M.; Vodnik, Vesna; Gajić, Radoš

    2018-03-01

    The adsorption of thiacyanine dye molecules on citrate-stabilized silver nanoparticle clusters drop-cast onto freshly cleaved mica or highly oriented pyrolytic graphite surfaces is examined using colocalized surface-enhanced Raman spectroscopy and atomic force microscopy. The incidence of dye Raman signatures in photoluminescence hotspots identified around nanoparticle clusters is considered for both citrate- and borate-capped silver nanoparticles and found to be substantially lower in the former case, suggesting that the citrate anions impede the efficient dye adsorption. Rigorous numerical simulations of light scattering on random nanoparticle clusters are used for estimating the electromagnetic enhancement and elucidating the hotspot formation mechanism. The majority of the enhanced Raman signal, estimated to be more than 90%, is found to originate from the nanogaps between adjacent nanoparticles in the cluster, regardless of the cluster size and geometry.

  14. Mechanism of melting in submonolayer films of nitrogen molecules adsorbed on the basal planes of graphite

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Bruch, Ludwig Walter; Taub, H.

    1995-01-01

    The melting mechanism in submonolayer films of N-2 molecules adsorbed on the basal planes of graphite is studied using molecular-dynamics simulations. The melting is strongly correlated with the formation of vacancies in the films. As the temperature increases, the edges of the submonolayer patch...

  15. Organo-halogenated contaminants (OHCs) in the sediments from the Soan River, Pakistan: OHCs(adsorbed TOC) burial flux, status and risk assessment.

    Science.gov (United States)

    Malik, Riffat Naseem; Mehboob, Fouzia; Ali, Usman; Katsoyiannis, Athanasios; Schuster, Jasmin K; Moeckel, Claudia; Jones, Kevin C

    2014-05-15

    In this study, regression analysis revealed that TOC is the principal factor in controlling the fate of organo-halogenated contaminants (OHCs: PCBs, PBDEs, OCPs) in Soan River, Pakistan. The OHCs(adsorbed TOC) burial flux (OHCs(adsorbed TOC)Bf; mg/cm(2)·yr) was calculated in the following ranges: ∑PCBs (0.07-0.31), ∑PBDEs (0.005-0.029), ∑HCHs (0.015-0.046) and ∑DDTs (0.007-0.039). Apart from OHCs(adsorbed TOC)Bf, the levels of OHCs were in the following order: PCBs>DDTs>PBDEs>HCH>Chlordane>HCB. PBDEs and PCB congener patterns showed following order respectively: BDE-149>-153>-18>-138>-44 and PCB-149>-153>-18>-138>-44. DDT isomers and metabolites' pattern were p,p'-DDT>p,p'-DDD>p,p'-DDE>o,p'-DDT>o,p'-DDD>o,p'-DDE and HCHs were β-HCH>α-HCH>γ-HCH>δ-HCH. PBDE composition had similarities to penta-BDE and DE-71 mixtures and PCBs with commercial products Aroclor-1254 and -1260. (DDE+DDD)/∑DDTs and p,p'-DDT/p,p'-DDE suggested the recent input of DDTs in sediments while α/γ-HCH indicated past usage of lindane and technical mixtures. Risk assessment suggested that Soan River and its tributaries are potentially at risk against most of the OHCs. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Stability, structural and electronic properties of benzene molecule adsorbed on free standing Au layer

    Energy Technology Data Exchange (ETDEWEB)

    Katoch, Neha, E-mail: nehakatoch2@gmail.com; Kapoor, Pooja; Sharma, Munish; Ahluwalia, P. K. [Physics Department, Himachal Pradesh University, Shimla, Himachal Pradesh, India 171005 (India); Kumar, Ashok [Center for Physical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, India, 151001 (India)

    2016-05-23

    We report stability and electronic properties of benzene molecule adsorbed on the Au atomic layer within the framework of density function theory (DFT). Horizontal configuration of benzene on the top site of Au monolayer prefers energetically over other studied configurations. On the adsorption of benzene, the ballistic conductance of Au monolayer is found to decrease from 4G{sub 0} to 2G{sub 0} suggesting its applications for the fabrications of organic sensor devices based on the Au atomic layers.

  17. Controlled enzymatic cutting of DNA molecules adsorbed on surfaces using soft lithography

    Science.gov (United States)

    Auerbach, Alyssa; Budassi, Julia; Shea, Emily; Zhu, Ke; Sokolov, Jonathan

    2013-03-01

    The enzyme DNase I was applied to adsorbed and aligned DNA molecules (Lamda, 48.5 kilobase pairs (kbp), and T4, 165.6 kbp), stretched linearly on a surface, by stamping with a polydimethylsiloxane (PDMS) grating. The DNAs were cut by the enzyme into separated, micron-sized segments along the length of the molecules at positions determined by the grating dimensions (3-20 microns). Ozone-treated PDMS stamps were coated with DNase I solutions and placed in contact with surface-adsorbed DNA molecules deposited on a 750 polymethylmethacrylate (PMMA) film spun-cast onto a silicon substrate. The stamps were applied under pressure for times up to 15 minutes at 37 C. The cutting was observed by fluorescence microscopy imaging of DNA labeled with YOYO dye. Cutting was found to be efficient despite the steric hindrance due to surface attachment of the molecules. Methods for detaching and separating the cut segments for sequencing applications will be discussed. Supported by NSF-DMR program.

  18. Thermodynamic characteristics of the adsorption of organic molecules on modified MCM-41 adsorbents

    Science.gov (United States)

    Gus'kov, V. Yu.; Sukhareva, D. A.; Salikhova, G. R.; Karpov, S. I.; Kudasheva, F. Kh.; Roessner, F.; Borodina, E. V.

    2017-07-01

    The adsorption of a number of organic molecules on samples of MCM-41 adsorbent modified with dichloromethylphenylsilane and subsequently treated with sulfuric acid (MDCS) and N-trimethoxysilylpropyl- N, N, N-trimethylammonium chloride (MNM) is studied. Specific retention volumes equal to the Henry constant are determined by means of inverse gas chromatography at infinite dilution. The thermodynamic characteristics of adsorption, the dispersive and specific components of the Helmholtz energy of adsorption, and the increment of the methyl group to the heat of adsorption are calculated. It is shown that the grafting of aminosilane and phenylsilane groups enhances the forces of dispersion and reduces specific interactions. A greater drop in polarity is observed for MDCS than for MNM, due to the stronger polarity of amoinosilane; the enthalpy factor makes the main contribution to the adsorption of organic compounds on the investigated adsorbents. It is found that the MNM sample is capable of the irreversible adsorption of alcohols.

  19. In situ STM imaging of the structures of pentacene molecules adsorbed on Au(111).

    Science.gov (United States)

    Pong, Ifan; Yau, Shuehlin; Huang, Peng-Yi; Chen, Ming-Chou; Hu, Tarng-Shiang; Yang, Yawchia; Lee, Yuh-Lang

    2009-09-01

    In situ scanning tunneling microscope (STM) was used to examine the spatial structures of pentacene molecules adsorbed onto a Au(111) single-crystal electrode from a benzene dosing solution containing 16-400 microM pentacene. Molecular-resolution STM imaging conducted in 0.1 M HClO(4) revealed highly ordered pentacene structures of ( radical31 x radical31)R8.9 degrees , (3 x 10), ( radical31 x 10), and ( radical7 x 2 radical7)R19.1 degrees adsorbed on the reconstructed Au(111) electrode dosed with different pentacene solutions. These pentacene structures and the reconstructed Au(111) substrate were stable between 0.2 and 0.8 V [vs reversible hydrogen electrode, RHE]. Increasing the potential to E > 0.8 V lifted the reconstructed Au(111) surface and disrupted the ordered pentacene adlattices simultaneously. Ordered pentacene structures could be restored by applying potentials negative enough to reinforce the reconstructed Au(111). At potentials negative of 0.2 V, the adsorption of protons became increasingly important to displace adsorbed pentacene admolecules. Although the reconstructed Au(111) structure was not essential to produce ordered pentacene adlayers, it seemed to help the adsorption of pentacene molecules in a long-range ordered pattern. At room temperature (25 degrees C), approximately 100 pentacene molecules seen in STM images could rotate and align themselves to a neighboring domain in 10 s, suggesting that pentacene admolecules could be mobile on Au(111) under the STM imaging conditions of -150 mV in bias voltage and 1 nA in feedback current.

  20. Spins of adsorbed molecules investigated by the detection of Kondo resonance

    Science.gov (United States)

    Komeda, Tadahiro

    2014-12-01

    Surface magnetism has been one of the platforms to explore the magnetism in low dimensions. It is also a key component for the development of quantum information processes, which utilizes the spin degree of freedom. The Kondo resonance is a phenomenon that is caused by an interaction between an isolated spin and conduction electrons. First observed in the 1930s as an anomalous increase in the low-temperature resistance of metals embedded with magnetic atoms, the Kondo physics mainly studied the effects of bulk magnetic impurities in the resistivity. In the last 15 years it has undergone a revival by a scanning tunneling microscope (STM) which enables the measurement of the Kondo resonance at surfaces using an atomic scale point contact. The detection of the Kondo resonance can be a powerful tool to explore surface magnetism. In this article, I review recent studies of the surface spin of adsorbed molecules by the detection of the Kondo resonance. Researches on metal phthalocyanine (MPc) and porphyrin molecules will be examined. In addition, the Kondo resonance for double-decker lanthanoide Pc molecules will be discussed. Some of the double-decker Pc molecules show single-molecule magnet (SMM) behavior, which attracts attention as a material for electronic devices. For both classes, the ligand plays a crucial role in determining the parameters of the Kondo resonance, such as the Kondo temperature and the change of the shape from peak to Fano-dip. In addition, the spin in delocalized molecular orbital forms the Kondo resonance, which shows significant differences from the Kondo resonance formed by the metal spins. Since molecular orbital can be tuned in a flexible manner by the design of the molecule, the Kondo resonance formed by delocalized molecular orbital might expand the knowledge of this field.

  1. High resolution spectroscopy on adsorbed molecules on a Ni (110)-surface: vibrational states and electronic levels

    International Nuclear Information System (INIS)

    Kardinal, I.

    1998-01-01

    The complementary techniques of HR-XPS and HREELS have been applied to two distinct problems. The first studies adsorption and dissociation of C 2 N 2 on Ni (110) at room temperature (RT) and at 90 K and its co-adsorption with CO. At RT C 2 N 2 dissociates and forms a c(2x2)-CN structure. The resulting CN is found to be bound in the grooves of the (110) surface yielding the lowest C-N vibrational energy yet observed. C 2 N 2 was found to dissociate even at 90 K however the resulting CN overlayer after warming to RT showed remarkable differences to that of the RT adsorption. As well as the in-groove species a number of adsorption sites on the ridges with a bond order higher have been identified. Preadsorbed CO is completely driven of the Ni (110) surface by co-adsorption of CN at RT. HREELS indicates that first CO is desorbed from the on-top-sites and then from the bridge-sites of the (110)-ridges involving a considerable increase of the HREELS cross section for the CO on the bridge-sites. Also the signal intensity of the coadsorbed CN is suppressed by the CO present on the surface. The second study investigated the adsorption of bithiophene (BiT) on clean Ni (110) and the S-modified c(2x2)-S-Ni (110) and p(4x1)-S-Ni (110). The latter provided a strongly structured substrate which forced the assembly of the adsorbed BiT-molecules. The high degree of order of this adsorbate/substrate system was obvious in both the HR-XPS results and the BREELS results with strong azimuthal anisotropy. This system was used to asses the ability to use the HREELS impact selection rules to determine molecular orientation of a reasonably complex adsorbate overlayer. (author)

  2. First-principles study of pollutant molecules absorbed on polymeric adsorbents using the vdW-DF2 functional

    Science.gov (United States)

    Zhu, Jinguo; Wang, Yapeng; Tian, Ting; Zhang, Qianfan

    2018-03-01

    Polymeric adsorbents have been attracting increasing attention because of their favorable structrual properties and effectiveness of solving small molecules contaminants. However, due to the absence of deep insight into the adsorption mechanism of polymeric adsorbents, researches on new polymeric adsorbents can only be carried out by repeated experiments and tests, which is extremely inefficient. Therefore, investigating the adsorption process of polymeric adsorbents, especially the mechanism of adsorbing various air pollutant molecules by materials modelling and simulation, is of great significance. Here in this work, we systematically studied the adsorption mechanism by first-principles computation with van der Waals interaction. It demonstrates that the adsorption between them was pure physisorption originating from the hydrogen bond and intermolecular forces consisting of Keesom force, Debye force and London dispersion force. The proportions of these forces varied according to different adsorption systems. The adsorption effects were determined by the polymers’ dipole moment and polarizability. The adsorption performance of some polymers with special structures was also investigated to explore their possibility as potential adsorbents. The results of our simulation can provide some guidance for developing new polymeric adsorbents with better performance.

  3. Electronic structures of spinterface for thiophene molecule adsorbed at Co, Fe, and Ni electrode: First principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Linlin; Tian, Yanli; Yuan, Xiaobo; Hu, Guichao; Ren, Junfeng, E-mail: renjf@sdnu.edu.cn

    2016-12-15

    Highlights: • Thiophene molecule could be spin polarized when adsorbed at Co(001), Fe(100), and Ni(111) surfaces. • The biggest spin polarization will be obtained when the thiophene molecule adsorbed at the Fe(100) surface. • The spin polarization is originated from the interfacial orbital hybridizations between the 3d orbital of ferromagnetic electrodes and the 2p orbital of the thiophene molecule. - Abstract: First principles calculations are adopted to study the spin polarization properties of thiophene molecule which adsorbed at the Co, Fe, and Ni electrode surfaces. The density of states, spin-polarized density distributions as well as the differential charge density distributions are obtained. It is found that the p orbital of the thiophene molecule will interact with the d orbital of the ferromagnetic electrodes, which will generate new spin coupling states and lead to obvious spin polarization in the thiophene molecule. Different electrodes induce different spin polarization properties, and in which the Fe electrode will bring the biggest spin polarization of the thiophene molecule. People can selectively and efficiently inject spin polarized electrons into molecules by choosing suitable ferromagnetic electrodes in organic spintronic devices.

  4. Resonance energy transfer from solid to adsorbed molecules under radiolysis of the N2O-MgO system

    International Nuclear Information System (INIS)

    Volkov, A.I.

    1986-01-01

    The radiolysis mechanism of nitrous oxide adsorbed on magnesia has been studied at 77 K using e.s.r. spectroscopy and chromatography. The radiative decomposition of nitrous oxide is shown to take place not only during the dissociative capture of electrons, but also during the interaction of its molecules with magnesia exitons. At a monolayer coverage theta 2 O molecules and exitons to a molecular one as a result of raising the irradiation temperature of nitrous oxide adsorbed on magnesia (theta=0.5) has been revealed. (author)

  5. Nuclear magnetic resonance study of the structure of simple molecules adsorbed on metal surfaces: acetylene on platinum

    International Nuclear Information System (INIS)

    Wang, P.K.

    1984-01-01

    We have used NMR to determine the structure of acetylene (HC - CH) adsorbed at room temperature on small platinum particles by studying the 13 C- 13 C, 13 C- 1 H, and 1 H- 1 H dipolar interactions among the nuclei in the adsorbed molecules. We find a model of 77% CCH 2 and 23% HCCH to be the only one consistent with all of our data. The C-C bond length of the majority species, CCH 2 , is determined as 1.44 +- 0.02 A, midway between a single and double bond, suggesting that both carbon atoms bond to the surface. 36 references, 29 figures, 1 table

  6. Direct comparison of the electronic coupling efficiency of sulfur and selenium alligator clips for molecules adsorbed onto gold electrodes

    International Nuclear Information System (INIS)

    Patrone, L.; Palacin, S.; Bourgoin, J.P.

    2003-01-01

    Scanning tunneling microscopy experiments have been performed to compare the electronic coupling provided by S and by Se used as alligator clips for bisthiol- and biselenol-terthiophene molecules adsorbed onto gold. The molecules were inserted in a dodecanethiol (DT) self-assembled monolayer. Their apparent height above the dodecanethiol matrix was used as a measure of the electronic coupling strength corresponding to S and Se, respectively. We show that the insertion behaviors of the two molecules are qualitatively the same, and that Se provides systematically a better coupling link than S, whatever the tunneling conditions

  7. NMR diffusion and relaxation measurements of organic molecules adsorbed in porous media

    International Nuclear Information System (INIS)

    Gjerdaaker, Lars

    2002-01-01

    a bipolar form of the pulsed field gradient has proved to be an efficient method for both reducing the cross-term between the applied and internal gradient and reducing the eddy current dead time. Without the use of a bipolar sequence, the measured diffusivities are likely to be underestimated. In order to get sufficient attenuation of the signal a stimulated-echo sequence together with magnetic field gradients have been used. It was then possible to increase the z-storage period to compensate for insufficient gradient strength. However, the employed diffusion probe and gradient power supply are able to generate magnetic field gradients that make the z-storage period unnecessary. In this work we also present a spin-echo analogue to the 13-interval PFGSTE sequence presented by Cotts et al., a so-called 11-interval bipolar PFGSE sequence. Conclusions: The molecular dynamics of four organic adsorbates confined in porous materials have been investigated. The confinement gives rise to substantial changes in the phase behaviour and molecular dynamics. From the line shape of the confined substances a narrow-line component superimposed on a broad resonance is observed at temperatures well below the transition point of the bulk material. This narrow-line component is, in the freezing region, attributed to the surface layer and the undercooled liquid in the smaller pores that remains unfrozen. In the low-temperature region, the narrow-line component corresponds to the surface layer, while the broad component originates from the crystalline phase at the centre of the pores. The persistent surface layer does not appear to crystallize at all, and a relatively high diffusion rate of this liquid-like phase is observed over a wide temperature range, even well below the transition point of the bulk material. However, with decreasing temperature T2 of the molecules in the surface layer becomes shorter and the contribution to the NMR signal decreases gradually. For pivalic acid and

  8. Total internal reflection sum-frequency generation spectroscopy and dense gold nanoparticles monolayer: a route for probing adsorbed molecules

    International Nuclear Information System (INIS)

    Tourillon, Gerard; Dreesen, Laurent; Volcke, Cedric; Sartenaer, Yannick; Thiry, Paul A; Peremans, Andre

    2007-01-01

    We show that sum-frequency generation spectroscopy performed in the total internal reflection configuration (TIR-SFG) combined with a dense gold nanoparticles monolayer allows us to study, with an excellent signal to noise ratio and high signal to background ratio, the conformation of adsorbed molecules. Dodecanethiol (DDT) was used as probe molecules in order to assess the potentialities of the approach. An enhancement of more than one order of magnitude of the SFG signals arising from the adsorbed species is observed with the TIR geometry compared to the external reflection one while the SFG non-resonant contribution remains the same for both configurations. Although further work is required to fully understand the origin of the SFG process on nanoparticles, our work opens new possibilities for studying nanostructures

  9. 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.

  10. Inkjet-Printed Small-Molecule Organic Light-Emitting Diodes: Halogen-Free Inks, Printing Optimization, and Large-Area Patterning.

    Science.gov (United States)

    Zhou, Lu; Yang, Lei; Yu, Mengjie; Jiang, Yi; Liu, Cheng-Fang; Lai, Wen-Yong; Huang, Wei

    2017-11-22

    Manufacturing small-molecule organic light-emitting diodes (OLEDs) via inkjet printing is rather attractive for realizing high-efficiency and long-life-span devices, yet it is challenging. In this paper, we present our efforts on systematical investigation and optimization of the ink properties and the printing process to enable facile inkjet printing of conjugated light-emitting small molecules. Various factors on influencing the inkjet-printed film quality during the droplet generation, the ink spreading on the substrates, and its solidification processes have been systematically investigated and optimized. Consequently, halogen-free inks have been developed and large-area patterning inkjet printing on flexible substrates with efficient blue emission has been successfully demonstrated. Moreover, OLEDs manufactured by inkjet printing the light-emitting small molecules manifested superior performance as compared with their corresponding spin-cast counterparts.

  11. Preparation of theoretical scanning tunneling microscope images of adsorbed molecules: a theoretical study of benzene on the Cu(110) surface

    International Nuclear Information System (INIS)

    Shapter, J.G.; Rogers, B.L.; Ford, M.J.

    2003-01-01

    Full text: Since its development in 1982, the Scanning Tunneling Microscope (STM) has developed into a powerful tool for the study of surfaces and adsorbates. However, the utility of the technique can be further enhanced through the development of techniques for generating theoretical STM images. This is particularly true when studying molecules adsorbed on a substrate, as the results are often interpreted superficially due to an inadequate understanding of the orbital overlap probed in the experiment. A method of preparing theoretical scanning tunneling microscope (STM) images using comparatively inexpensive desktop computers and the commercially available CRYSTAL98 package is presented through a study of benzene adsorbed on the Cu(110) surface. Density Functional Theory (DFT) and Hartree-Fock (HF) methods are used to model clean Cu(110) slabs of various thicknesses and to simulate the adsorption of benzene onto these slabs. Eight possible orientations of benzene on the Cu(110) surface are proposed, and the optimum orientation according to the calculations is presented. Theoretical STM images of the Cu(110) surface and benzene adsorbed on the Cu(110) surface are compared with experimental STM images of the system from a published study. Significant differences are observed and are examined in detail

  12. 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).

  13. Nonadiabatic effects on surfaces: Kohn anomaly, electronic damping of adsorbate vibrations, and local heating of single molecules

    International Nuclear Information System (INIS)

    Kroeger, J

    2008-01-01

    Three aspects of electron-phonon coupling at metal surfaces are reviewed. One aspect is the Kohn effect, which describes an anomalous dispersion relation of surface phonons due to quasi-one-dimensional nesting of Fermi surface contours. The combination of electron energy loss spectroscopy and angle-resolved photoelectron spectroscopy allows us to unambiguously characterize Kohn anomaly systems. A second aspect is the nonadiabatic damping of adsorbate vibrations. Characteristic spectroscopic line shapes of vibrational modes allow us to estimate the amount of energy transfer between the vibrational mode and electron-hole pairs. Case studies of a Kohn anomaly and nonadiabatic damping are provided by the hydrogen- and deuterium-covered Mo(110) surface. As a third aspect of interaction between electrons and phonons, local heating of a C 60 molecule adsorbed on Cu(100) and in contact with the tip of a scanning tunnelling microscope is covered

  14. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    International Nuclear Information System (INIS)

    Kenny, T.W.

    1989-05-01

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of 4 He adsorbed on metallic films. In contrast to measurements of 4 He adsorbed on all other insulating substrates, we have shown that 4 He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, 4 He adsorbed on sapphire and on Ag films and H 2 adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs

  15. Sensitivity of photoelectron diffraction to conformational changes of adsorbed molecules: Tetra-tert-butyl-azobenzene/Au(111

    Directory of Open Access Journals (Sweden)

    A. Schuler

    2017-01-01

    Full Text Available Electron diffraction is a standard tool to investigate the atomic structure of surfaces, interfaces, and adsorbate systems. In particular, photoelectron diffraction is a promising candidate for real-time studies of structural dynamics combining the ultimate time resolution of optical pulses and the high scattering cross-sections for electrons. In view of future time-resolved experiments from molecular layers, we studied the sensitivity of photoelectron diffraction to conformational changes of only a small fraction of molecules in a monolayer adsorbed on a metallic substrate. 3,3′,5,5′-tetra-tert-butyl-azobenzene served as test case. This molecule can be switched between two isomers, trans and cis, by absorption of ultraviolet light. X-ray photoelectron diffraction patterns were recorded from tetra-tert-butyl-azobenzene/Au(111 in thermal equilibrium at room temperature and compared to patterns taken in the photostationary state obtained by exposing the surface to radiation from a high-intensity helium discharge lamp. Difference patterns were simulated by means of multiple-scattering calculations, which allowed us to determine the fraction of molecules that underwent isomerization.

  16. The metrics of surface adsorbed small molecules on the Young's fringe dual-slab waveguide interferometer

    International Nuclear Information System (INIS)

    Cross, Graham H; Reeves, Andrew; Brand, Stuart; Swann, Marcus J; Peel, Louise L; Freeman, Neville J; Lu, Jian R

    2004-01-01

    A method for analysing thin films using a dual-waveguide interferometric technique is described. Alternate dual polarization addressing of the interferometer sensor using a ferroelectric liquid crystal polarization switch allowed the opto-geometrical properties (density and thickness) of adsorbed layers at a solid-liquid interface to be determined. Differences in the waveguide mode dispersion between the transverse electric and transverse magnetic modes allowed unique combinations of layer thickness and refractive index to be determined at all stages of the layer formation process. The technique has been verified by comparing the analysis of the surface adsorption of surfactants with data obtained using neutron scattering techniques, observing their behaviour on trimethylsilane coated silicon oxynitride surfaces. The data obtained were found to be in excellent agreement with analogous neutron scattering experiments and the precision of the measurements taken to be of the order of 40 pm with respect to adsorbed layer thicknesses. The study was extended to a series of surfactants whose layer morphology could be correlated with their hydrophilicity/lipophilicity balance. Those in the series with longer alkyl chains were observed to form thinner, denser layers at the hydrophobic solid/aqueous liquid interface and the degree of order attained at sub-critical micelle concentrations to be correlated with molecular fluidity. The technique is expected to find utility with those interested in thin film analysis. An important and growing area of application is within the life sciences, especially in the field of protein structure and function

  17. Adsorbed states of chlorophenol on Cu(110) and controlled switching of single-molecule junctions

    Energy Technology Data Exchange (ETDEWEB)

    Okuyama, H., E-mail: hokuyama@kuchem.kyoto-u.ac.jp; Kitaguchi, Y.; Hattori, T.; Ueda, Y.; Ferrer, N. G.; Hatta, S.; Aruga, T. [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)

    2016-06-28

    A molecular junction of substituted benzene (chlorophenol) is fabricated and controlled by using a scanning tunneling microscope (STM). Prior to the junction formation, the bonding geometry of the molecule on the surface is characterized by STM and electron energy loss spectroscopy (EELS). EELS shows that the OH group of chlorophenol is dissociated on Cu(110) and that the molecule is bonded nearly flat to the surface via an O atom, with the Cl group intact. We demonstrate controlled contact of an STM tip to the “available” Cl group and lift-up of the molecule while it is anchored to the surface via an O atom. The asymmetric bonding motifs of the molecule to the electrodes allow for reversible control of the junction.

  18. Detection of gas molecules on single Mn adatom adsorbed graphyne: a DFT-D study

    Science.gov (United States)

    Lu, Zhansheng; Lv, Peng; Ma, Dongwei; Yang, Xinwei; Li, Shuo; Yang, Zongxian

    2018-02-01

    As one of the prominent applications in intelligent systems, gas sensing technology has attracted great interest in both industry and academia. In the current study, the pristine graphyne (GY) without and with a single Mn atom is investigated to detect the gas molecules (CO, CH4, CO2, NH3, NO and O2). The pristine GY is promising to detect O2 molecules because of its chemical adsorption on GY with large electron transfer. The great stability of the Mn/GY is found, and the Mn atom prefers to anchor at the alkyne ring as a single atom. Upon single Mn atom anchoring, the sensitivity and selectivity of GY based gas sensors is significantly improved for various molecules, except CH4. The recovery time of the Mn/GY after detecting the gas molecules may help to appraise the detection efficiency for the Mn/GY. The current study will help to understand the mechanism of detecting the gas molecules, and extend the potentially fascinating applications of GY-based materials.

  19. Collective effects, relaxation and localization of hole levels in atoms, molecules, solids, and adsorbates

    International Nuclear Information System (INIS)

    Wendin, G.

    1979-01-01

    Recent progress in descriptions of photoelectron spectra is reviewed with emphasis on cases where the one-electron and quasi-particle approximations break down and the hole level becomes spread over a number of discrete lines or a continuum or both. Unifying aspects and similarities between interaction processes in atoms, molecules and solids are stressed. 38 references

  20. Slow Diffusive Motions in a Monolayer of Tetracosane Molecules Adsorbed on Graphite

    DEFF Research Database (Denmark)

    Taub, H.; Hansen, Flemming Yssing; Criswell, L.

    2004-01-01

    to a temperature of similar to230 K, we observe the QNS energy width to be dispersionless, consistent with molecular dynamics simulations showing rotational motion of the molecules about their long axis. At 260 K, the QNS energy width begins to increase with wave vector transfer, suggesting onset of nonuniaxial...

  1. Tribochemical synthesis of nano-lubricant films from adsorbed molecules at sliding solid interface: Tribo-polymers from α-pinene, pinane, and n-decane

    Science.gov (United States)

    He, Xin; Barthel, Anthony J.; Kim, Seong H.

    2016-06-01

    The mechanochemical reactions of adsorbed molecules at sliding interfaces were studied for α-pinene (C10H16), pinane (C10H18), and n-decane (C10H22) on a stainless steel substrate surface. During vapor phase lubrication, molecules adsorbed at the sliding interface could be activated by mechanical shear. Under the equilibrium adsorption condition of these molecules, the friction coefficient of sliding steel surfaces was about 0.2 and a polymeric film was tribochemically produced. The synthesis yield of α-pinene tribo-polymers was about twice as much as pinane tribo-polymers. In contrast to these strained bicyclic hydrocarbons, n-decane showed much weaker activity for tribo-polymerization at the same mechanical shear condition. These results suggested that the mechanical shear at tribological interfaces could induce the opening of the strained ring structure of α-pinene and pinane, which leads to polymerization of adsorbed molecules at the sliding track. On a stainless steel surface, such polymerization reactions of adsorbed molecules do not occur under typical surface reaction conditions. The mechanical properties and boundary lubrication efficiency of the produced tribo-polymer films are discussed.

  2. Phase properties of elastic waves in systems constituted of adsorbed diatomic molecules on the (001) surface of a simple cubic crystal

    Science.gov (United States)

    Deymier, P. A.; Runge, K.

    2018-03-01

    A Green's function-based numerical method is developed to calculate the phase of scattered elastic waves in a harmonic model of diatomic molecules adsorbed on the (001) surface of a simple cubic crystal. The phase properties of scattered waves depend on the configuration of the molecules. The configurations of adsorbed molecules on the crystal surface such as parallel chain-like arrays coupled via kinks are used to demonstrate not only linear but also non-linear dependency of the phase on the number of kinks along the chains. Non-linear behavior arises for scattered waves with frequencies in the vicinity of a diatomic molecule resonance. In the non-linear regime, the variation in phase with the number of kinks is formulated mathematically as unitary matrix operations leading to an analogy between phase-based elastic unitary operations and quantum gates. The advantage of elastic based unitary operations is that they are easily realizable physically and measurable.

  3. Surface Chemistry Dependence of Mechanochemical Reaction of Adsorbed Molecules-An Experimental Study on Tribopolymerization of α-Pinene on Metal, Metal Oxide, and Carbon Surfaces.

    Science.gov (United States)

    He, Xin; Kim, Seong H

    2018-02-20

    Mechanochemical reactions between adsorbate molecules sheared at tribological interfaces can induce association of adsorbed molecules, forming oligomeric and polymeric products often called tribopolymers). This study revealed the role or effect of surface chemistry of the solid substrate in mechanochemical polymerization reactions. As a model reactant, α-pinene was chosen because it was known to readily form tribopolymers at the sliding interface of stainless steel under vapor-phase lubrication conditions. Eight different substrate materials were tested-palladium, nickel, copper, stainless steel, gold, silicon oxide, aluminum oxide, and diamond-like carbon (DLC). All metal substrates and DLC were initially covered with surface oxide species formed naturally in air or during the oxidative sample cleaning. It was found that the tribopolymerization yield of α-pinene is much higher on the substrates that can chemisorb α-pinene, compared to the ones on which only physisorption occurs. From the load dependence of the tribopolymerization yield, it was found that the surfaces capable of chemisorption give a smaller critical activation volume for the mechanochemical reaction, compared to the ones capable of physisorption only. On the basis of these observations and infrared spectroscopy analyses of the adsorbed molecules and the produced polymers, it was concluded that the mechanochemical reaction mechanisms might be different between chemically reactive and inert surfaces and that the chemical reactivity of the substrate surface greatly influences the tribochemical polymerization reactions of adsorbed molecules.

  4. Rotationally adiabatic pair interactions of para- and ortho-hydrogen with the halogen molecules F2, Cl2, and Br2.

    Science.gov (United States)

    Berg, Matthias; Accardi, Antonio; Paulus, Beate; Schmidt, Burkhard

    2014-08-21

    The present work is concerned with the weak interactions between hydrogen and halogen molecules, i.e., the interactions of pairs H2-X2 with X = F, Cl, Br, which are dominated by dispersion and quadrupole-quadrupole forces. The global minimum of the four-dimensional (4D) coupled cluster with singles and doubles and perturbative triples (CCSD(T)) pair potentials is always a T shaped structure where H2 acts as the hat of the T, with well depths (De) of 1.3, 2.4, and 3.1 kJ/mol for F2, Cl2, and Br2, respectively. MP2/AVQZ results, in reasonable agreement with CCSD(T) results extrapolated to the basis set limit, are used for detailed scans of the potentials. Due to the large difference in the rotational constants of the monomers, in the adiabatic approximation, one can solve the rotational Schrödinger equation for H2 in the potential of the X2 molecule. This yields effective two-dimensional rotationally adiabatic potential energy surfaces where pH2 and oH2 are point-like particles. These potentials for the H2-X2 complexes have global and local minima for effective linear and T-shaped complexes, respectively, which are separated by 0.4-1.0 kJ/mol, where oH2 binds stronger than pH2 to X2, due to higher alignment to minima structures of the 4D-pair potential. Further, we provide fits of an analytical function to the rotationally adiabatic potentials.

  5. Transfer of chirality from adsorbed chiral molecules to the substrates highlighted by circular dichroism in angle-resolved valence photoelectron spectroscopy

    DEFF Research Database (Denmark)

    Contini, G.; Turchini, S.; Sanna, Simone

    2012-01-01

    Studies of self-assembled chiral molecules on achiral metallic surfaces have mostly focused on the determination of the geometry of adsorbates and their electronic structure. The aim of this paper is to provide direct information on the chirality character of the system and on the chirality...... transfer from molecules to substrate by means of circular dichroism in the angular distribution of valence photoelectrons for the extended domain of the chiral self-assembled molecular structure, formed by alaninol adsorbed on Cu(100). We show, by the dichroic behavior of a mixed molecule–copper valence...... state, that the presence of molecular chiral domains induces asymmetry in the interaction with the substrate and locally transfers the chiral character to the underlying metal atoms participating in the adsorption process; combined information related to the asymmetry of the initial electronic state...

  6. Effect of substrate thickness on ejection of phenylalanine molecules adsorbed on free-standing graphene bombarded by 10 keV C{sub 60}

    Energy Technology Data Exchange (ETDEWEB)

    Golunski, M. [Institute of Physics, Jagiellonian University, ul. Lojasiewicza 11, 30-348 Krakow (Poland); Verkhoturov, S.V.; Verkhoturov, D.S.; Schweikert, E.A. [Department of Chemistry, Texas A& M University, College Station, TX 77840 (United States); Postawa, Z., E-mail: zbigniew.postawa@uj.edu.pl [Institute of Physics, Jagiellonian University, ul. Lojasiewicza 11, 30-348 Krakow (Poland)

    2017-02-15

    Highlights: • Substrate thickness has a prominent effect on the molecular ejection mechanism. • Collisions with projectile atoms leads to molecular ejection at thin substrates. • Interactions with deforming graphene sheet ejects molecules from thicker substrates. • Probability of fragmentation process decreases with the graphene substrate thickness. - Abstract: Molecular dynamics computer simulations have been employed to investigate the effect of substrate thickness on the ejection mechanism of phenylalanine molecules deposited on free-standing graphene. The system is bombarded from the graphene side by 10 keV C{sub 60} projectiles at normal incidence and the ejected particles are collected both in transmission and reflection directions. It has been found that the ejection mechanism depends on the substrate thickness. At thin substrates mostly organic fragments are ejected by direct collisions between projectile atoms and adsorbed molecules. At thicker substrates interaction between deforming topmost graphene sheet and adsorbed molecules becomes more important. As this process is gentle and directionally correlated, it leads predominantly to ejection of intact molecules. The implications of the results to a novel analytical approach in Secondary Ion Mass Spectrometry based on ultrathin free-standing graphene substrates and a transmission geometry are discussed.

  7. Evidence for Interfacial Halogen Bonding.

    Science.gov (United States)

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

    2016-05-10

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

  8. Element-specific and site-specific ion desorption from adsorbed molecules by deep core-level photoexcitation at the K-edges

    CERN Document Server

    Baba, Y H

    2003-01-01

    This article reviews our recent works on the ion desorption from adsorbed and condensed molecules at low temperature following the core-level photoexcitations using synchrotron soft x-rays. The systems investigated here are adsorbed molecules with relatively heavy molecular weight containing third-row elements such as Si, P, S, and Cl. Compared with molecules composed of second-row elements, the highly element-specific and site-specific fragment-ion desorption were observed when we tune the photon energy at the dipole-allowed 1s -> sigma sup * (3p sup *) resonance. On the basis of the resonance Auger decay spectra around the 1s ionization thresholds, the observed highly specific ion desorption is interpreted by the localization of the excited electrons (here we call as 'spectator electrons') in the antibonding sigma sup * orbital. In order to separate the direct photo-induced process from the indirect processes triggered by the secondary electrons, the photon-stimulated ion desorption was also investigated in...

  9. Adatom Bond Dissociation in the Collision Between an Adsorbed Atom and Incident Diatomic Molecule: A Classical Trajectory Study

    International Nuclear Information System (INIS)

    Bayhan, U.

    2004-01-01

    The collisional dissociation of the Atom-Surface bond in the diatomic molecule (gas) / atom (ads) collision taking place on a bcc-structure surface have been studied by classical trajectory methods over the collision energy ranges and the attractive well depth of the diatomic molecule (gas) / atom (ads) interactions

  10. Halogenated fatty acids

    DEFF Research Database (Denmark)

    Mu, Huiling; Sundin, Peter; Wesén, Clas

    1997-01-01

    Halogenated fatty acids are the major contributors to organohalogen compounds in lipids of marine mammals, fish, and bivalves. For the initial characterization of these recently noticed compounds, a determination of the halogen concentration has usually been combined with some lipid isolation......), atomic emission spectrometry, and mass spectrometry. For most environmental samples, chlorinated FAMEs must be enriched prior to GC. ELCD is a useful detection method for indicating halogenated FAMEs in the chromatograms, and tentative identification of the halogenated species can be obtained...

  11. Electron stimulated desorption of cations from C sub 6 H sub 6 and C sub 6 H sub 1 sub 2 molecules adsorbed on Pt(1 1 1) and Ar spacer layer

    CERN Document Server

    Kawanowa, H; Hanatani, K; Gotoh, Y; Souda, R

    2003-01-01

    Mechanisms of electron stimulated cation desorption have been investigated for adsorbed C sub 6 H sub 6 and C sub 6 H sub 1 sub 2 molecules on the Pt(1 1 1) surface and the Ar spacer layer formed on it. The ion yields from the molecules adsorbed on the Ar spacer layer are highly enhanced at the smallest coverage and decay steeply with increasing coverage. No such enhancement was observed when they are adsorbed directly on the Pt(1 1 1) substrate. This behavior is explained in terms of the Coulombic repulsion of cations confined in nanoclusters, together with the delocalization of valence holes on the Pt(1 1 1) substrate as well as in the multilayer hydrocarbons. The holes in the C sub 6 H sub 6 molecule are more delocalized than those in the C sub 6 H sub 1 sub 2 molecule due to the overlap of pi orbitals.

  12. Surface-Enhanced Raman Spectroscopy of Dye and Thiol Molecules Adsorbed on Triangular Silver Nanostructures: A Study of Near-Field Enhancement, Localization of Hot-Spots, and Passivation of Adsorbed Carbonaceous Species

    Directory of Open Access Journals (Sweden)

    Manuel R. Gonçalves

    2012-01-01

    Full Text Available Surface-enhanced Raman spectroscopy (SERS of thiols and dye molecules adsorbed on triangular silver nanostructures was investigated. The SERS hot-spots are localized at the edges and corners of the silver triangular particles. AFM and SEM measurements permit to observe many small clusters formed at the edges of triangular particles fabricated by nanosphere lithography. Finite-element calculations show that near-field enhancements can reach values of more than 200 at visible wavelengths, in the gaps between small spherical particles and large triangular particles, although for the later no plasmon resonance was found at the wavelengths investigated. The regions near the particles showing strong near-field enhancement are well correlated with spatial localization of SERS hot-spots done by confocal microscopy. Silver nanostructures fabricated by thermal evaporation present strong and fast fluctuating SERS activity, due to amorphous carbon contamination. Thiols and dye molecules seem to be able to passivate the undesired SERS activity on fresh evaporated silver.

  13. Surface-Enhanced Raman Spectroscopy of Dye and Thiol Molecules Adsorbed on Triangular Silver Nano structures: A Study of Near-Field Enhancement, Localization of Hot-Spots, and Passivation of Adsorbed Carbonaceous Species

    International Nuclear Information System (INIS)

    Goncalves, M.R.; Marti, O.; Fabian Enderle, F.

    2012-01-01

    Surface-enhanced Raman spectroscopy (SERS) of thiols and dye molecules adsorbed on triangular silver nanostructures was investigated. The SERS hot-spots are localized at the edges and corners of the silver triangular particles. AFM and SEM measurements permit to observe many small clusters formed at the edges of triangular particles fabricated by nanosphere lithography. Finite-element calculations show that near-field enhancements can reach values of more than 200 at visible wavelengths, in the gaps between small spherical particles and large triangular particles, although for the later no plasmon resonance was found at the wavelengths investigated. The regions near the particles showing strong near-field enhancement are well correlated with spatial localization of SERS hot-spots done by confocal microscopy. Silver nanostructures fabricated by thermal evaporation present strong and fast fluctuating SERS activity, due to amorphous carbon contamination. Thiols and dye molecules seem to be able to passivate the undesired SERS activity on fresh evaporated silver. excitation: by far-field illumination of metal nanostructures or rough metal Raman scattering cross-section of gold-palladium target Temporal Fluctuation in SERS Temporal and spectral fluctuations.

  14. Density functional theory study the effects of oxygen-containing functional groups on oxygen molecules and oxygen atoms adsorbed on carbonaceous materials.

    Science.gov (United States)

    Qi, Xuejun; Song, Wenwu; Shi, Jianwei

    2017-01-01

    Density functional theory was used to study the effects of different types of oxygen-containing functional groups on the adsorption of oxygen molecules and single active oxygen atoms on carbonaceous materials. During gasification or combustion reactions of carbonaceous materials, oxygen-containing functional groups such as hydroxyl(-OH), carbonyl(-CO), quinone(-O), and carboxyl(-COOH) are often present on the edge of graphite and can affect graphite's chemical properties. When oxygen-containing functional groups appear on a graphite surface, the oxygen molecules are strongly adsorbed onto the surface to form a four-member ring structure. At the same time, the O-O bond is greatly weakened and easily broken. The adsorption energy value indicates that the adsorption of oxygen molecules changes from physisorption to chemisorption for oxygen-containing functional groups on the edge of a graphite surface. In addition, our results indicate that the adsorption energy depends on the type of oxygen-containing functional group. When a single active oxygen atom is adsorbed on the bridge site of graphite, it gives rise to a stable epoxy structure. Epoxy can cause deformation of the graphite lattice due to the transition of graphite from sp2 to sp3 after the addition of an oxygen atom. For quinone group on the edge of graphite, oxygen atoms react with carbon atoms to form the precursor of CO2. Similarly, the single active oxygen atoms of carbonyl groups can interact with edge carbon atoms to form the precursor of CO2. The results show that oxygen-containing functional groups on graphite surfaces enhance the activity of graphite, which promotes adsorption on the graphite surface.

  15. Vibrational dynamics of adsorbed molecules under conditions of photodesorption: Pump-probe SFG spectra of CO/Pt(111)

    Science.gov (United States)

    Fournier, Frédéric; Zheng, Wanquan; Carrez, Serge; Dubost, Henri; Bourguignon, Bernard

    2004-09-01

    Interaction of CO adsorbed on Pt(111) with electrons and phonons is studied experimentally by means of a pump-probe experiment where CO is probed by IR+visible sum frequency generation under a pump laser intensity that allows photodesorption. Vibrational spectra of CO internal stretch are obtained as a function of pump-probe delay. A two-temperature and anharmonic coupling model is used to extract from the spectra the real time variations of CO peak frequency and dephasing time. The main conclusions are the following: (i) The CO stretch is perturbed by two low-frequency modes, assigned to frustrated rotation and frustrated translation. (ii) The frustrated rotation is directly coupled to electrons photoexcited in Pt(111) by the pump laser. (iii) There is no evidence of Pt-CO stretch excitation in the spectra. The implications for the photodesorption dynamics are discussed.

  16. First-principles investigations of electronic and magnetic properties of SrTiO3 (001) surfaces with adsorbed ethanol and acetone molecules

    Science.gov (United States)

    Adeagbo, Waheed A.; Fischer, Guntram; Hergert, Wolfram

    2011-05-01

    First-principles methods based on density functional theory are used to investigate the electronic and magnetic properties of molecular interaction of the TiO2 terminated SrTiO3 (100) surface with ethanol or acetone. Both the perfect surface and the surface with an oxygen or a titanium vacancy in the top layer are considered. Ethanol and acetone are preferentially adsorbed molecularly via their respective oxygen atom on top of the Ti atom on the perfect surface. In case of an oxygen vacancy the adsorption of ethanol or acetone occurs directly on top of the vacancy and does not significantly affect the magnetism caused by the vacancy. In the case of a titanium vacancy both adsorbates occupy positions above Ti atoms. During this adsorption process the ethanol molecule dissociates into a CH3CO radical and three hydrogen atoms. The latter form hydroxide bonds with three of the four dangling oxygen bonds around the Ti vacancy and any magnetic moment induced by the Ti vacancy is annihilated. Thus the ethanol and acetone have a different impact on the surface magnetism of the SrTiO3 (100) surface.

  17. Frontier molecular orbitals of a single molecule adsorbed on thin insulating films supported by a metal substrate: electron and hole attachment energies.

    Science.gov (United States)

    Scivetti, Iván; Persson, Mats

    2017-09-06

    We present calculations of vertical electron and hole attachment energies to the frontier orbitals of a pentacene molecule absorbed on multi-layer sodium chloride films supported by a copper substrate using a simplified density functional theory (DFT) method. The adsorbate and the film are treated fully within DFT, whereas the metal is treated implicitly by a perfect conductor model. We find that the computed energy gap between the highest and lowest unoccupied molecular orbitals-HOMO and LUMO -from the vertical attachment energies increases with the thickness of the insulating film, in agreement with experiments. This increase of the gap can be rationalised in a simple dielectric model with parameters determined from DFT calculations and is found to be dominated by the image interaction with the metal. We find, however, that this simplified model overestimates the downward shift of the energy gap in the limit of an infinitely thick film.

  18. New small molecule inhibitors of histone methyl transferase DOT1L with a nitrile as a non-traditional replacement for heavy halogen atoms.

    Science.gov (United States)

    Spurr, Sophie S; Bayle, Elliott D; Yu, Wenyu; Li, Fengling; Tempel, Wolfram; Vedadi, Masoud; Schapira, Matthieu; Fish, Paul V

    2016-09-15

    A number of new nucleoside derivatives are disclosed as inhibitors of DOT1L activity. SARs established that DOT1L inhibition could be achieved through incorporation of polar groups and small heterocycles at the 5-position (5, 6, 12) or by the application of alternative nitrogenous bases (18). Based on these results, CN-SAH (19) was identified as a potent and selective inhibitor of DOT1L activity where the polar 5-nitrile group was shown by crystallography to bind in the hydrophobic pocket of DOT1L. In addition, we show that a polar nitrile group can be used as a non-traditional replacement for heavy halogen atoms. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. On the widths of Stokes lines in Raman scattering from molecules adsorbed at metal surfaces and in molecular conduction junctions

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yi, E-mail: yig057@ucsd.edu; Galperin, Michael, E-mail: migalperin@ucsd.edu [Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093 (United States); Nitzan, Abraham, E-mail: nitzan@post.tau.ac.il [Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA and School of Chemistry, Tel Aviv University, Tel Aviv 69978 (Israel)

    2016-06-28

    Within a generic model we analyze the Stokes linewidth in surface enhanced Raman scattering (SERS) from molecules embedded as bridges in molecular junctions. We identify four main contributions to the off-resonant Stokes signal and show that under zero voltage bias (a situation pertaining also to standard SERS experiments) and at low bias junctions only one of these contributions is pronounced. The linewidth of this component is determined by the molecular vibrational relaxation rate, which is dominated by interactions with the essentially bosonic thermal environment when the relevant molecular electronic energy is far from the metal(s) Fermi energy(ies). It increases when the molecular electronic level is close to the metal Fermi level so that an additional vibrational relaxation channel due to electron-hole (eh) exciton in the molecule opens. Other contributions to the Raman signal, of considerably broader linewidths, can become important at larger junction bias.

  20. Orbital tomography: Molecular band maps, momentum maps and the imaging of real space orbitals of adsorbed molecules

    Energy Technology Data Exchange (ETDEWEB)

    Offenbacher, Hannes; Lüftner, Daniel; Ules, Thomas; Reinisch, Eva Maria; Koller, Georg, E-mail: georg.koller@uni-graz.at; Puschnig, Peter; Ramsey, Michael G., E-mail: michael.ramsey@uni-graz.at

    2015-10-01

    Highlights: • Orbital tomography within the plane wave final state approximation. • One electron orbital predictions versus angle resolved photoemission experiment. • Geometric and electronic structure of organic thin films elucidated by ARUPS. • Influence of molecular conformation and orientation on ARUPS. • Retrieval of sexiphenyl and pentacene orbitals in real space. - Abstract: The frontier orbitals of molecules are the prime determinants of their chemical, optical and electronic properties. Arguably, the most direct method of addressing the (filled) frontier orbitals is ultra-violet photoemission spectroscopy (UPS). Although UPS is a mature technique from the early 1970s on, the angular distribution of the photoemitted electrons was thought to be too complex to be analysed quantitatively. Recently angle resolved UPS (ARUPS) work on conjugated molecules both, in ordered thick films and chemisorbed monolayers, has shown that the angular (momentum) distribution of the photocurrent from orbital emissions can be simply understood. The approach, based on the assumption of a plane wave final state is becoming known as orbital tomography. Here we will demonstrate, with selected examples of pentacene (5A) and sexiphenyl (6P), the potential of orbital tomography. First it will be shown how the full angular distribution of the photocurrent (momentum map) from a specific orbital is related to the real space orbital by a Fourier transform. Examples of the reconstruction of 5A orbitals will be given and the procedure for recovering the lost phase information will be outlined. We then move to examples of sexiphenyl where we interrogate the original band maps of thick sexiphenyl in the light of our understanding of orbital tomography that has developed since then. With comparison to theoretical simulations of the molecular band maps, the molecular conformation and orientation will be concluded. New results for the sexiphenyl monolayer on Al(1 1 0) will then be

  1. Excited-state potential-energy surfaces of metal-adsorbed organic molecules from linear expansion Δ-self-consistent field density-functional theory (ΔSCF-DFT).

    Science.gov (United States)

    Maurer, Reinhard J; Reuter, Karsten

    2013-07-07

    Accurate and efficient simulation of excited state properties is an important and much aspired cornerstone in the study of adsorbate dynamics on metal surfaces. To this end, the recently proposed linear expansion Δ-self-consistent field method by Gavnholt et al. [Phys. Rev. B 78, 075441 (2008)] presents an efficient alternative to time consuming quasi-particle calculations. In this method, the standard Kohn-Sham equations of density-functional theory are solved with the constraint of a non-equilibrium occupation in a region of Hilbert-space resembling gas-phase orbitals of the adsorbate. In this work, we discuss the applicability of this method for the excited-state dynamics of metal-surface mounted organic adsorbates, specifically in the context of molecular switching. We present necessary advancements to allow for a consistent quality description of excited-state potential-energy surfaces (PESs), and illustrate the concept with the application to Azobenzene adsorbed on Ag(111) and Au(111) surfaces. We find that the explicit inclusion of substrate electronic states modifies the topologies of intra-molecular excited-state PESs of the molecule due to image charge and hybridization effects. While the molecule in gas phase shows a clear energetic separation of resonances that induce isomerization and backreaction, the surface-adsorbed molecule does not. The concomitant possibly simultaneous induction of both processes would lead to a significantly reduced switching efficiency of such a mechanism.

  2. Implanting very low energy atomic ions into surface adsorbed cage molecules: the formation/emission of Cs/C60+

    International Nuclear Information System (INIS)

    Kolodney, Eli; Kaplan, Andrey; Manor, Yoni; Bekkerman, Anatoly; Tsipinyuk, Boris

    2004-01-01

    Full Text: We demonstrate the formation of an endo-complex via a collision of energetic ions with molecular overlayers on a surface. An incoming atomic ion is encapsulated inside a very large molecule or cluster by implanting the primary ion into the target species, which then recovers its original structure or rearrange itself around the implanted ion in some stable configuration. Here we describe an experiment resulting in the formation and ejection of an endo-complex, within a single collision. We study the formation and emission of endohedral fullerenes, Cs/C 60 + and Cs/C 70 + , following a single collision of Cs + ion with a sub-monolayer of C 60 (steady state coverage) on gold and silicon surfaces and with a sub-monolayer of C 70 on gold. A continuous low energy (E 0 =35-220 eV) Cs + ion beam hit the Cs + covered surface and the collisional formation and ejection of the endohedral Cs/Cs 60 + complex, within a single Cs + /C 60 collision was observed and characterized. Several experimental observations clearly demonstrate the single collision nature of the combined atom penetration endo-complex ejection event. The fullerene molecule is actually being picked up off the surface by the penetrating Cs + ion. The evidence for the trapping of the Cs + ion inside the fullerene cage is given both by the appearance of the Cs/Cs (602-2n) + (n=1-5) sequence and its termination at Cs/Cs 50 + . Kinetic Energy Distributions (KEDs) of the outgoing Cs/Cs 60 + were measured for two different Cs + impact energies under field-free conditions. The most striking observation is the near independence of the KEDs on the impact energy. Both KEDs peak around 1.2 eV with similar line shapes. A simple model for the formation/ejection/fragmentation dynamics of the endohedral complex is proposed and is found to be in good agreement with the experimental results

  3. Modeling adsorption: Investigating adsorbate and adsorbent properties

    Science.gov (United States)

    Webster, Charles Edwin

    1999-12-01

    Surface catalyzed reactions play a major role in current chemical production technology. Currently, 90% of all chemicals are produced by heterogeneously catalyzed reactions. Most of these catalyzed reactions involve adsorption, concentrating the substrate(s) (the adsorbate) on the surface of the solid (the adsorbent). Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. Molecular properties such as molecular volumes and projected molecular areas are needed in order to convert moles adsorbed to surface volumes and areas. Generally, these molecular properties have been estimated from bulk properties, but many assumptions are required. As a result, different literature values are employed for these essential molecular properties. Calculated molar volumes and excluded molecular areas are determined and tabulated for a variety of molecules. Molecular dimensions of molecules are important in the understanding of molecular exclusion as well as size and shape selectivity, diffusion, and adsorbent selection. Molecular dimensions can also be used in the determination of the effective catalytic pore size of a catalyst. Adsorption isotherms, on zeolites, (crystalline mineral oxides) and amorphous solids, can be analyzed with the Multiple Equilibrium Analysis (MEA) description of adsorption. The MEA produces equilibrium constants (Ki), capacities (ni), and thermodynamic parameters (enthalpies, ΔHi, and entropies, ΔSi) of adsorption for each process. Pore volumes and accessible surface areas are calculated from the process capacities. Adsorption isotherms can also be predicted for existing and new adsorbate-adsorbent systems with the MEA. The results show that MEA has the potential of becoming a standard characterization method for microporous solids that will lead to an increased understanding of their behavior in gas

  4. Expansion Hamiltonian model for a diatomic molecule adsorbed on a surface: Vibrational states of the CO/Cu(100) system including surface vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Qingyong, E-mail: mengqingyong@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, 116023 Dalian (China); Meyer, Hans-Dieter, E-mail: hans-dieter.meyer@pci.uni-heidelberg.de [Theoretische Chemie, Physikalisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

    2015-10-28

    Molecular-surface studies are often done by assuming a corrugated, static (i.e., rigid) surface. To be able to investigate the effects that vibrations of surface atoms may have on spectra and cross sections, an expansion Hamiltonian model is proposed on the basis of the recently reported [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES), which was built for the CO/Cu(100) system with a rigid surface. In contrast to other molecule-surface coupling models, such as the modified surface oscillator model, the coupling between the adsorbed molecule and the surface atoms is already included in the present expansion SAP-PES model, in which a Taylor expansion around the equilibrium positions of the surface atoms is performed. To test the quality of the Taylor expansion, a direct model, that is avoiding the expansion, is also studied. The latter, however, requests that there is only one movable surface atom included. On the basis of the present expansion and direct models, the effects of a moving top copper atom (the one to which CO is bound) on the energy levels of a bound CO/Cu(100) system are studied. For this purpose, the multiconfiguration time-dependent Hartree calculations are carried out to obtain the vibrational fundamentals and overtones of the CO/Cu(100) system including a movable top copper atom. In order to interpret the results, a simple model consisting of two coupled harmonic oscillators is introduced. From these calculations, the vibrational levels of the CO/Cu(100) system as function of the frequency of the top copper atom are discussed.

  5. Enhanced binding capacity of boronate affinity adsorbent via surface modification of silica by combination of atom transfer radical polymerization and chain-end functionalization for high-efficiency enrichment of cis-diol molecules

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei; He, Maofang; Wang, Chaozhan; Wei, Yinmao, E-mail: ymwei@nwu.edu.cn

    2015-07-30

    Boronate affinity materials have been widely used for specific separation and preconcentration of cis-diol molecules, but most do not have sufficient capacity due to limited binding sites on the material surface. In this work, we prepared a phenylboronic acid-functionalized adsorbent with a high binding capacity via the combination of surface-initiated atom transfer radical polymerization (SI-ATRP) and chain-end functionalization. With this method, the terminal chlorides of the polymer chains were used fully, and the proposed adsorbent contains dense boronic acid polymers chain with boronic acid on the chain end. Consequently, the proposed adsorbent possesses excellent selectivity and a high binding capacity of 513.6 μmol g{sup −1} for catechol and 736.8 μmol g{sup −1} for fructose, which are much higher than those of other reported adsorbents. The dispersed solid-phase extraction (dSPE) based on the prepared adsorbent was used for extraction of three cis-diol drugs (i.e., epinephrine, isoprenaline and caffeic acid isopropyl ester) from plasma; the eluates were analyzed by HPLC-UV. The reduced amount of adsorbent (i.e., 2.0 mg) could still eliminate interferences efficiently and yielded a recovery range of 85.6–101.1% with relative standard deviations ranging from 2.5 to 9.7% (n = 5). The results indicated that the proposed strategy could serve as a promising alternative to increase the density of surface functional groups on the adsorbent; thus, the prepared adsorbent has the potential to effectively enrich cis-diol substances in real samples. - Highlights: • Boronate adsorbent is prepared via ATRP and chain-end functionalization. • The adsorbent has quite high binding capacity for cis-diols. • Binding capacity is easily manipulated by ATRP condition. • Chain-end functionalization can improve binding capacity significantly. • Reduced adsorbent is consumed in dispersed solid-phase extraction of cis-diols.

  6. Measurement of laser activated electron tunneling from semiconductor zinc oxide to adsorbed organic molecules by a matrix assisted laser desorption ionization mass spectrometer

    International Nuclear Information System (INIS)

    Zhong Hongying; Fu Jieying; Wang Xiaoli; Zheng Shi

    2012-01-01

    Highlights: ► Irradiation of photons with energies more than the band gap generates electron–hole pairs. ► Electron tunneling probability is dependent on the electron mobility. ► Tunneling electrons are captured by charge deficient atoms. ► Unpaired electrons induce cleavages of chemical bonds. - Abstract: Measurement of light induced heterogeneous electron transfer is important for understanding of fundamental processes involved in chemistry, physics and biology, which is still challenging by current techniques. Laser activated electron tunneling (LAET) from semiconductor metal oxides was observed and characterized by a MALDI (matrix assisted laser desorption ionization) mass spectrometer in this work. Nanoparticles of ZnO were placed on a MALDI sample plate. Free fatty acids and derivatives were used as models of organic compounds and directly deposited on the surface of ZnO nanoparticles. Irradiation of UV laser (λ = 355 nm) with energy more than the band gap of ZnO produces ions that can be detected in negative mode. When TiO 2 nanoparticles with similar band gap but much lower electron mobility were used, these ions were not observed unless the voltage on the sample plate was increased. The experimental results indicate that laser induced electron tunneling is dependent on the electron mobility and the strength of the electric field. Capture of low energy electrons by charge-deficient atoms of adsorbed organic molecules causes unpaired electron-directed cleavages of chemical bonds in a nonergodic pathway. In positive detection mode, electron tunneling cannot be observed due to the reverse moving direction of electrons. It should be able to expect that laser desorption ionization mass spectrometry is a new technique capable of probing the dynamics of electron tunneling. LAET offers advantages as a new ionization dissociation method for mass spectrometry.

  7. Dynamics of cyanophenyl alkylbenzoate molecules in the bulk and in a surface layer adsorbed onto aerosil. Variation of the lengths of the alkyl chain

    Energy Technology Data Exchange (ETDEWEB)

    Frunza, Stefan [National Institute of Materials Physics, R-077125 Magurele (Romania); Schoenhals, Andreas [BAM Federal Institute of Materials Research and Testing, D-12205 Berlin (Germany); Frunza, Ligia, E-mail: lfrunza@infim.ro [National Institute of Materials Physics, R-077125 Magurele (Romania); Beica, Traian; Zgura, Irina; Ganea, Paul [National Institute of Materials Physics, R-077125 Magurele (Romania); Stoenescu, Daniel [Telecom-Bretagne, Departement d' Optique, Technopole Brest-Iroise 29238 Cedex (France)

    2010-06-16

    Graphical abstract: The temperature dependence of the molecular mobility in composites shows an Arrhenius-type regime at low temperature and a glassy-type one at higher temperature separated by a crossover phenomenon. - Abstract: The molecular mobility of 4-butyl- and 4-pentyl-4'-cyanophenyl benzoate (CP4B, CP5B) and their composites prepared from aerosil A380 was investigated by broadband dielectric spectroscopy in a large temperature range. Thermogravimetric and infrared investigations were additionally performed. High silica density (larger than 7 g aerosil/1 g of liquid crystal) was selected to observe a thin layer adsorbed on the surface of the silica particles. The data were compared with those of the member of the series with six carbon atoms in the alkyl tail. Bulk CP4B and CP5B show the dielectric behaviour expected for liquid crystals. For the composites one relaxation process is observed at frequencies much lower than those for the corresponding bulk, which was assigned to the dynamics of the molecules in a surface layer. The temperature dependence of the relaxation rates (and of the dielectric strength) shows a crossover behaviour with two distinguished regimes. At higher temperatures the data obey the Vogel-Fulcher-Tammann law, whereas an Arrhenius law is observed at lower temperature, in a close similarity to the behaviour of a constrained dynamic glass transition. The estimated Vogel and crossover temperature is independent on the tail length, while the activation energy for the low temperature branch increases weakly with increasing the alkyl tail.

  8. Theoretical study of stability and charge-transport properties of coronene molecule and some of its halogenated derivatives: A path to ambipolar organic-based materials?

    Energy Technology Data Exchange (ETDEWEB)

    Sancho-García, J. C., E-mail: jc.sancho@ua.es; Pérez-Jiménez, A. J., E-mail: aj.perez@ua.es [Departamento de Química Física, Universidad de Alicante, E-03080 Alicante (Spain)

    2014-10-07

    We have carefully investigated the structural and electronic properties of coronene and some of its fluorinated and chlorinated derivatives, including full periphery substitution, as well as the preferred orientation of the non-covalent dimer structures subsequently formed. We have paid particular attention to a set of methodological details, to first obtain single-molecule magnitudes as accurately as possible, including next the use of modern dispersion-corrected methods to tackle the corresponding non-covalently bound dimers. Generally speaking, this class of compounds is expected to self-assembly in neighboring π-stacks with dimer stabilization energies ranging from –20 to –30 kcal mol{sup −1} at close distances around 3.0–3.3 Å. Then, in a further step, we have also calculated hole and electron transfer rates of some suitable candidates for ambipolar materials, and corresponding charge mobility values, which are known to critically depend on the supramolecular organization of the samples. For coronene and per-fluorinated coronene, we have found high values for their hopping rates, although slightly smaller for the latter due to an increase (decrease) of the reorganization energies (electronic couplings)

  9. 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...

  10. Extending the range of low energy electron diffraction (LEED) surface structure determination: Co-adsorbed molecules, incommensurate overlayers and alloy surface order studied by new video and electron counting LEED techniques

    International Nuclear Information System (INIS)

    Ogletree, D.F.

    1986-11-01

    LEED multiple scattering theory is briefly summarized, and aspects of electron scattering with particular significance to experimental measurements such as electron beam coherence, instrument response and phonon scattering are analyzed. Diffuse LEED experiments are discussed. New techniques that enhance the power of LEED are described, including a real-time video image digitizer applied to LEED intensity measurements, along with computer programs to generate I-V curves. The first electron counting LEED detector using a ''wedge and strip'' position sensitive anode and digital electronics is described. This instrument uses picoampere incident beam currents, and its sensitivity is limited only by statistics and counting times. Structural results on new classes of surface systems are presented. The structure of the c(4 x 2) phase of carbon monoxide adsorbed on Pt(111) has been determined, showing that carbon monoxide molecules adsorb in both top and bridge sites, 1.85 +- 0.10 A and 1.55 +- 0.10 A above the metal surface, respectively. The structure of an incommensurate graphite overlayer on Pt(111) is analyzed. The graphite layer is 3.70 +- 0.05 A above the metal surface, with intercalated carbon atoms located 1.25 +- 0.10 A above hollow sites supporting it. The (2√3 x 4)-rectangular phase of benzene and carbon monoxide coadsorbed on Pt(111) is analyzed. Benzene molecules adsorb in bridge sites parallel to and 2.10 +- 0.10 A above the surface. The carbon ring is expanded, with an average C-C bond length of 1.72 +- 0.15 A. The carbon monoxide molecules also adsorb in bridge sites. The structure of the (√3 x √3) reconstruction on the (111) face of the α-CuAl alloy has been determined

  11. Extending the range of low energy electron diffraction (LEED) surface structure determination: Co-adsorbed molecules, incommensurate overlayers and alloy surface order studied by new video and electron counting LEED techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ogletree, D.F.

    1986-11-01

    LEED multiple scattering theory is briefly summarized, and aspects of electron scattering with particular significance to experimental measurements such as electron beam coherence, instrument response and phonon scattering are analyzed. Diffuse LEED experiments are discussed. New techniques that enhance the power of LEED are described, including a real-time video image digitizer applied to LEED intensity measurements, along with computer programs to generate I-V curves. The first electron counting LEED detector using a ''wedge and strip'' position sensitive anode and digital electronics is described. This instrument uses picoampere incident beam currents, and its sensitivity is limited only by statistics and counting times. Structural results on new classes of surface systems are presented. The structure of the c(4 x 2) phase of carbon monoxide adsorbed on Pt(111) has been determined, showing that carbon monoxide molecules adsorb in both top and bridge sites, 1.85 +- 0.10 A and 1.55 +- 0.10 A above the metal surface, respectively. The structure of an incommensurate graphite overlayer on Pt(111) is analyzed. The graphite layer is 3.70 +- 0.05 A above the metal surface, with intercalated carbon atoms located 1.25 +- 0.10 A above hollow sites supporting it. The (2..sqrt..3 x 4)-rectangular phase of benzene and carbon monoxide coadsorbed on Pt(111) is analyzed. Benzene molecules adsorb in bridge sites parallel to and 2.10 +- 0.10 A above the surface. The carbon ring is expanded, with an average C-C bond length of 1.72 +- 0.15 A. The carbon monoxide molecules also adsorb in bridge sites. The structure of the (..sqrt..3 x ..sqrt..3) reconstruction on the (111) face of the ..cap alpha..-CuAl alloy has been determined.

  12. Apparatus for washing out halogens

    Energy Technology Data Exchange (ETDEWEB)

    Pier, M; Hahn, J; Kroenig, W

    1941-03-26

    An apparatus is described for washing out of halogens and the like or liquid halogen compounds from the products, which are formed on pressure hydrogenation or splitting of carbon-containing material in the presence of halogens or halogen compounds, consisting of a washing apparatus installed between the reaction vessel and the hot separator, which is inclined in relatively small space for steam regulation and contains, with the steam, arranged baffles, especially spirals.

  13. 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

  14. 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.

  15. 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.

  16. Halogenation processes of secondary organic aerosol and implications on halogen release mechanisms

    Directory of Open Access Journals (Sweden)

    J. Ofner

    2012-07-01

    Full Text Available Reactive halogen species (RHS, such as X·, X2 and HOX containing X = chlorine and/or bromine, are released by various sources like photo-activated sea-salt aerosol or from salt pans, and salt lakes. Despite many studies of RHS reactions, the potential of RHS reacting with secondary organic aerosol (SOA and organic aerosol derived from biomass-burning (BBOA has been neglected. Such reactions can constitute sources of gaseous organohalogen compounds or halogenated organic matter in the tropospheric boundary layer and can influence physicochemical properties of atmospheric aerosols.

    Model SOA from α-pinene, catechol, and guaiacol was used to study heterogeneous interactions with RHS. Particles were exposed to molecular chlorine and bromine in an aerosol smog-chamber in the presence of UV/VIS irradiation and to RHS, released from simulated natural halogen sources like salt pans. Subsequently, the aerosol was characterized in detail using a variety of physicochemical and spectroscopic methods. Fundamental features were correlated with heterogeneous halogenation, which results in new functional groups (FTIR spectroscopy, changes UV/VIS absorption, chemical composition (ultrahigh resolution mass spectroscopy (ICR-FT/MS, or aerosol size distribution. However, the halogen release mechanisms were also found to be affected by the presence of organic aerosol. Those interaction processes, changing chemical and physical properties of the aerosol are likely to influence e.g. the ability of the aerosol to act as cloud condensation nuclei, its potential to adsorb other gases with low-volatility, or its contribution to radiative forcing and ultimately the Earth's radiation balance.

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

    Science.gov (United States)

    Sugibayashi, Yuji; Hayashi, Satoko; Nakanishi, Waro

    2016-08-18

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

  18. Tropospheric Halogen Chemistry

    Science.gov (United States)

    von Glasow, R.; Crutzen, P. J.

    2003-12-01

    Halogens are very reactive chemicals that are known to play an important role in anthropogenic stratospheric ozone depletion chemistry, first recognized by Molina and Rowland (1974). However, they also affect the chemistry of the troposphere. They are of special interest because they are involved in many reaction cycles that can affect the oxidation power of the atmosphere indirectly by influencing the main oxidants O3 and its photolysis product OH and directly, e.g., by reactions of the Cl radical with hydrocarbons (e.g., CH4).Already by the middle of the nineteenth century, Marchand (1852) reported the presence of bromine and iodine in rain and other natural waters. He also mentions the benefits of iodine in drinking water through the prevention of goitres and cretinism. In a prophetic monograph "Air and Rain: The Beginnings of a Chemical Climatology," Smith (1872) describes measurements of chloride in rain water, which he states to originate partly from the oceans by a process that he compares with the bursting of "soap bubbles" which produces "small vehicles" that transfer small spray droplets of seawater to the air. From deviations of the sulfate-to-chloride ratio in coastal rain compared to seawater, Smith concluded that chemical processes occur once the particles are airborne.For almost a century thereafter, however, atmospheric halogens received little attention. One exception was the work by Cauer (1939), who reported that iodine pollution has been significant in Western and Central Europe due to the inefficient burning of seaweed, causing mean gas phase atmospheric concentrations as high as or greater than 0.5 μg m-3. In his classical textbook Air Chemistry and Radioactivity, Junge (1963) devoted less than three pages to halogen gas phase chemistry, discussing chlorine and iodine. As reviewed by Eriksson (1959a, b), the main atmospheric source of halogens is sea salt, derived from the bursting of bubbles of air which are produced by ocean waves and other

  19. 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.

  20. 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).

  1. Targeted adsorption of molecules in the colon with the novel adsorbent-based medicinal product, DAV132: A proof of concept study in healthy subjects.

    Science.gov (United States)

    de Gunzburg, Jean; Ducher, Annie; Modess, Christiane; Wegner, Danilo; Oswald, Stefan; Dressman, Jennifer; Augustin, Violaine; Feger, Céline; Andremont, Antoine; Weitschies, Werner; Siegmund, Werner

    2015-01-01

    During antibiotic treatments, active residuals reaching the colon profoundly affect the bacterial flora resulting in the emergence of resistance. To prevent these effects, we developed an enteric-coated formulated activated-charcoal based product, DAV132, meant to deliver its adsorbent to the ileum and neutralize antibiotic residues in the proximal colon. In a randomized, control, crossover study, the plasma pharmacokinetics of the probe drugs amoxicillin (500 mg) absorbed in the proximal intestine, and sulfapyridine (25 mg) metabolized from sulfasalazine in the cecum and rapidly absorbed, were compared after a single administration in 18 healthy subjects who had received DAV132, uncoated formulated activated charcoal (FAC) or water 16 and 8 hours before, concomitantly with the probe drugs, and 8 hours thereafter. The AUC0-96 h of amoxicillin was reduced by more than 70% when it was taken with FAC, but bioequivalent when it was taken with water or DAV132. By contrast, the AUC0-96 h of sulfapyridine was reduced by more than 90% when administered with either FAC or DAV132 in comparison with water. The results show that DAV132 can selectively adsorb drug compounds in the proximal colon, without interfering with drug absorption in the proximal small intestine, thereby constituting a proof of concept that DAV132 actually functions in humans. © 2014, The American College of Clinical Pharmacology.

  2. 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.

  3. 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.

  4. Theory of sum-frequency generation spectroscopy of adsorbed molecules using the density matrix method-broadband vibrational sum-frequency generation and applications

    International Nuclear Information System (INIS)

    Bonn, M; Ueba, H; Wolf, M

    2005-01-01

    A generalized theory of frequency- and time-resolved vibrational sum-frequency generation (SFG) spectroscopy of adsorbates at surfaces is presented using the density matrix formalism. Our theoretical treatment is specifically aimed at addressing issues that accompany the relatively novel SFG approach using broadband infrared pulses. The ultrashort duration of these pulses makes them ideally suited for time-resolved investigations, for which we present a complete theoretical treatment. A second key characteristic of these pulses is their large bandwidth and high intensity, which allow for highly non-linear effects, including vibrational ladder climbing of surface vibrations. We derive general expressions relating the density matrix to SFG spectra, and apply these expressions to specific experimental results by solving the coupled optical Bloch equations of the density matrix elements. Thus, we can theoretically reproduce recent experimentally demonstrated hot band SFG spectra using femtosecond broadband infrared excitation of carbon monoxide (CO) on a Ru(001) surface

  5. A classical trajectory study of the adatom -surface bond dissociation in the collision reaction between an adsorbed H atom and an N2 molecule

    International Nuclear Information System (INIS)

    Bayhan, U.

    2005-01-01

    The collisionnal dissociation of the Adatom-Surface bond in the diatomic molecule N2(gas)/H(ads) collision taking place on a W(100) bcc-structure surface have been studied by classical trajectory method over the collision energy ranges (0.1-2.0 eV ) and the attractive well depth (0.19-4.0 eV). of the N2 molecule (gas)/H(ads) interactions. When the energy accumulate into the adatom bond, thus leading to a a large dissociation probability

  6. Electronic structure of CoPc adsorbed on Ag(100): Evidence for molecule-substrate interaction mediated by Co 3d orbitals

    Czech Academy of Sciences Publication Activity Database

    Salomon, E.; Amsalem, P.; Marom, N.; Vondráček, Martin; Kronik, L.; Koch, N.; Angot, T.

    2013-01-01

    Roč. 87, č. 7 (2013), "075407-1"-"075407-9" ISSN 1098-0121 R&D Projects: GA MŠk(CZ) LG12003 Institutional support: RVO:68378271 Keywords : cobalt-phthalocyanine * molecule-substrate interaction * photoemission spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.664, year: 2013

  7. A surprising way to control the charge transport in molecular electronics: the subtle impact of the coverage of self-assembled monolayers of floppy molecules adsorbed on metallic electrodes.

    Science.gov (United States)

    Bâldea, Ioan

    2017-10-26

    Inspired by earlier attempts in organic electronics aiming at controlling charge injection from metals into organic materials by manipulating the Schottky energy barrier using self-assembled monolayers (SAMs), recent experimental and theoretical work in molecular electronics showed that metal-organic interfaces can be controlled via changes in the metal work function that are induced by SAMs. In this paper we indicate a different route to achieve interface-driven control over the charge transfer/transport at the molecular scale. It is based on the fact that, in floppy molecule based SAMs, the molecular conformation can be tuned by varying the coverage of the adsorbate. We demonstrate this effect with the aid of benchmark molecules that are often used to fabricate nanojunctions and consist of two rings that can easily rotate relative to each other. We show that, by varying the coverage of the SAM, the twisting angle φ of the considered molecular species can be modified by a factor of two. Given the fact that the low bias conductance G scales as cos 2  φ, this results in a change in G of over one order of magnitude for the considered molecular species. Tuning the twisting angle by controlling the SAM coverage may be significant, e.g., for current efforts to fabricate molecular switches. Conversely, the lack of control over the local SAM coverage may be problematic for the reproducibility and interpretation of the STM (scanning tunneling microscope) measurements on repeatedly forming single molecule break junctions.

  8. Adsorber fires

    International Nuclear Information System (INIS)

    Holmes, W.

    1987-01-01

    The following conclusions are offered with respect to activated charcoal filter systems in nuclear power plants: (1) The use of activated charcoal in nuclear facilities presents a potential for deep-seated fires. (2) The defense-in-depth approach to nuclear fire safety requires that if an ignition should occur, fires must be detected quickly and subsequently suppressed. (3) Deep-seated fires in charcoal beds are difficult to extinguish. (4) Automatic water sprays can be used to extinguish fires rapidly and reliably when properly introduced into the burning medium. The second part of the conclusions offered are more like challenges: (1) The problem associated with inadvertent actuations of fire protection systems is not a major one, and it can be reduced further by proper design review, installation, testing, and maintenance. Eliminating automatic fire extinguishing systems for the protection of charcoal adsorbers is not justified. (2) Removal of automatic fire protection systems due to fear of inadvertent fire protection system operation is a case of treating the effect rather than the cause. On the other hand, properly maintaining automatic fire protection systems will preserve the risk of fire loss at acceptable levels while at the same time reducing the risk of damage presented by inadvertent operation of fire protection systems

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

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

    Science.gov (United States)

    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.

  17. Ecological applications of the irradiated adsorbents

    International Nuclear Information System (INIS)

    Tusseyev, T.

    2004-01-01

    Full text: In our previous works it was shown that after irradiation some adsorbents gain new interesting properties such as increasing (or decreasing) of their adsorption capacity, selectivity in relation to some gases, change of chemical bounds of gas molecules with adsorbent surface as well as other properties. We investigated a lot of adsorbents with semiconducting and dielectric properties. A high temperature superconductor was investigated also. Adsorbents were irradiated by ultraviolet (UV) and gamma - radiation, reactor (n.γ) - radiation, α-particles (E=40-50 MeV), protons ( E=30 MeV), and also He-3 ions (E-29-60 MeV). The following techniques were used: volumetric (manometrical), mass-spectrometer and IR spectroscopic methods, and also method of electronic - paramagnetic resonance (spin paramagnetic resonance) The obtained results allow to speak about creation of new adsorbents for gas purification (clearing) from harmful impurities, gas selection into components, an increasing of adsorbing surface. Thus one more advantage of the irradiated adsorbents is that they have 'memory effect', i.e. they can be used enough long time after irradiation. In laboratory conditions we built the small-sized adsorptive pump on the basis of the irradiated zeolites which are capable to work in autonomous conditions. It was found, that some of adsorbents after irradiation gain (or lose) selectivity in relation to definite gases. So, silica gel, which one in initial state does not adsorb hydrogen, after gamma irradiation it becomes active in relation to hydrogen. Some of rare earths oxides also show selectivity in relation to hydrogen and oxygen depending on a type of irradiation. Thus, it is possible to create different absorbents, depending on a solved problem, using a way or selection of adsorbents, either of radiation type and energy, as a result obtained adsorbents can be used for various ecological purposes

  18. Interplay of adsorbate-adsorbate and adsorbate-substrate interactions in self-assembled molecular surface nanostructures

    DEFF Research Database (Denmark)

    Schnadt, Joachim; Xu, Wei; Vang, Ronnie Thorbjørn

    2010-01-01

    a large tolerance to monatomic surface steps on the Ag(110) surface. The observed behaviour is explained in terms of strong intermolecular hydrogen bonding and a strong surface-mediated directionality, assisted by a sufficient degree of molecular backbone flexibility. In contrast, the same kind of step......-edge crossing is not observed when the molecules are adsorbed on the isotropic Ag(111) or more reactive Cu(110) surfaces. On Ag(111), similar 1-D assemblies are formed to those on Ag(110), but they are oriented along the step edges. On Cu(110), the carboxylic groups of NDCA are deprotonated and form covalent...... bonds to the surface, a situation which is also achieved on Ag(110) by annealing to 200 degrees C. These results show that the formation of particular self-assembled molecular nanostructures depends significantly on a subtle balance between the adsorbate-adsorbate and adsorbate-substrate interactions...

  19. 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.

  20. 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.

  1. 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

  2. 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).

  3. 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).

  4. 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.

  5. Friction and diffusion dynamics of adsorbates at surfaces

    NARCIS (Netherlands)

    Fusco, C.

    2005-01-01

    A theoretical study of the motion of adsorbates (e. g. atoms, molecules or clusters) on solid surfaces is presented, with a focus on surface diffusion and atomic-scale friction. These two phenomena are inextricably linked, because when an atomic or molecular adsorbate diffuses, or is pulled, it

  6. 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.

  7. Chloramination of nitrogenous contaminants (pharmaceuticals and pesticides): NDMA and halogenated DBPs formation.

    Science.gov (United States)

    Le Roux, Julien; Gallard, Hervé; Croué, Jean-Philippe

    2011-05-01

    Disinfection with chloramines is often used to reduce the production of regulated disinfection by-products (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). However, chloramination can lead to the formation of N-nitrosamines, including N-nitrosodimethylamine (NDMA), a probable human carcinogen. Previous research used dimethylamine (DMA) as a model precursor of NDMA, but certain widely used tertiary dimethylamines (e.g. the pharmaceutical ranitidine) show much higher conversion rates to NDMA than DMA. This study investigates the NDMA formation potential of several tertiary amines including pharmaceuticals and herbicides. The reactivity of these molecules with monochloramine (NH(2)Cl) is studied through the formation of NDMA, and other halogenated DBPs such as haloacetonitriles (HANs) and AOX (Adsorbable Organic Halides). Several compounds investigated formed NDMA in greater amounts than DMA, revealing the importance of structural characteristics of tertiary amines for NDMA formation. Among these compounds, the pharmaceutical ranitidine showed the highest molar conversion to NDMA. The pH and dissolved oxygen content of the solution were found to play a major role for the formation of NDMA from ranitidine. NDMA was formed in higher amounts at pH around pH 8 and a lower concentration of dissolved oxygen dramatically decreased NDMA yields. These findings seem to indicate that dichloramine (NHCl(2)) is not the major oxidant involved in the formation of NDMA from ranitidine, results in contradiction with the reaction mechanisms proposed in the literature. Dissolved oxygen was also found to influence the formation of other oxygen-containing DBPs (i.e. trichloronitromethane and haloketones). The results of this study identify several anthropogenic precursors of NDMA, indicating that chloramination of waters impacted by these tertiary amines could lead to the formation of significant amounts of NDMA and other non-regulated DBPs of potential health concern (e

  8. Chloramination of nitrogenous contaminants (pharmaceuticals and pesticides): NDMA and halogenated DBPs formation

    KAUST Repository

    Le Roux, Julien

    2011-05-01

    Disinfection with chloramines is often used to reduce the production of regulated disinfection by-products (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). However, chloramination can lead to the formation of N-nitrosamines, including N-nitrosodimethylamine (NDMA), a probable human carcinogen. Previous research used dimethylamine (DMA) as a model precursor of NDMA, but certain widely used tertiary dimethylamines (e.g. the pharmaceutical ranitidine) show much higher conversion rates to NDMA than DMA. This study investigates the NDMA formation potential of several tertiary amines including pharmaceuticals and herbicides. The reactivity of these molecules with monochloramine (NH2Cl) is studied through the formation of NDMA, and other halogenated DBPs such as haloacetonitriles (HANs) and AOX (Adsorbable Organic Halides). Several compounds investigated formed NDMA in greater amounts than DMA, revealing the importance of structural characteristics of tertiary amines for NDMA formation. Among these compounds, the pharmaceutical ranitidine showed the highest molar conversion to NDMA. The pH and dissolved oxygen content of the solution were found to play a major role for the formation of NDMA from ranitidine. NDMA was formed in higher amounts at pH around pH 8 and a lower concentration of dissolved oxygen dramatically decreased NDMA yields. These findings seem to indicate that dichloramine (NHCl2) is not the major oxidant involved in the formation of NDMA from ranitidine, results in contradiction with the reaction mechanisms proposed in the literature. Dissolved oxygen was also found to influence the formation of other oxygen-containing DBPs (i.e. trichloronitromethane and haloketones). The results of this study identify several anthropogenic precursors of NDMA, indicating that chloramination of waters impacted by these tertiary amines could lead to the formation of significant amounts of NDMA and other non-regulated DBPs of potential health concern (e

  9. 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.

  10. The Dynamics and Structures of Adsorbed Surfaces

    DEFF Research Database (Denmark)

    Nielsen, M; Ellenson, W. D.; McTague, J. P.

    1978-01-01

    . Elastic neutron diffraction measurements, determining the two-dimensional structural ordering of the adsorbed films, have been performed on layers of N2, Ar, H2, D2, O2, Kr, and He. Measurements on layers of larger molecules such as CD4 and ND3 have also been reported. Inelastic neutron scattering...... measurements, studying the dynamics of the adsorbed films are only possible in a few especially favourable cases such as 36Ar and D2 films, where the coherent phonon scattering cross-sections are very large. In other cases incoherent scattering from hydrogen can give information about e.g. the mobility...

  11. 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.

  12. 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.)

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. Black molecular adsorber coatings for spaceflight applications

    Science.gov (United States)

    Abraham, Nithin S.; Hasegawa, Mark M.; Straka, Sharon A.

    2014-09-01

    The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

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

    Directory of Open Access Journals (Sweden)

    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.

  1. Regenerative adsorbent heat pump

    Science.gov (United States)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative adsorbent heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system and at least a portion of the heat of adsorption. A series of at least four compressors containing an adsorbent is provided. A large amount of heat is transferred from compressor to compressor so that heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  2. 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.

  3. Adsorbates in a Box: Titration of Substrate Electronic States

    Science.gov (United States)

    Cheng, Zhihai; Wyrick, Jonathan; Luo, Miaomiao; Sun, Dezheng; Kim, Daeho; Zhu, Yeming; Lu, Wenhao; Kim, Kwangmoo; Einstein, T. L.; Bartels, Ludwig

    2010-08-01

    Nanoscale confinement of adsorbed CO molecules in an anthraquinone network on Cu(111) with a pore size of ≈4nm arranges the CO molecules in a shell structure that coincides with the distribution of substrate confined electronic states. Molecules occupy the states approximately in the sequence of rising electron energy. Despite the sixfold symmetry of the pore boundary itself, the adsorbate distribution adopts the threefold symmetry of the network-substrate system, highlighting the importance of the substrate even for such quasi-free-electron systems.

  4. 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.

  5. 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

  6. 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.

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

    KAUST Repository

    Ward, Jeremy W.

    2014-05-15

    Understanding the interactions at interfaces between the materials constituting consecutive layers within organic thin-film transistors (OTFTs) is vital for optimizing charge injection and transport, tuning thin-film microstructure, and designing 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 the performance of OTFTs is explored. By correlating the results from microbeam grazing incidence wide angle X-ray scattering (μGIWAXS) measurements of structure and texture with OTFT characteristics, two or more interaction paths between the terminating atoms of the semiconductor and the halogenated surface are found to be vital to templating a highly ordered morphology in the first layer. These interactions are effective when the separating distance is lower than 2.5 dw, where dw represents the van der Waals distance. The ability to modulate charge carrier transport by several orders of magnitude by promoting "edge-on" versus "face-on" molecular orientation and crystallographic textures in OSCs is demonstrated. It is found that the "edge-on" self-assembly of molecules forms uniform, (001) lamellar-textured crystallites which promote high charge carrier mobility, and that charge transport suffers as the fraction of the "face-on" oriented crystallites increases. The role of interfacial halogenation in mediating texture formation and the self-patterning of organic semiconductor films, as well as the resulting effects on charge transport in organic thin-film transistors, are explored. The presence of two or more anchoring sites between a halogenated semiconductor and a halogenated self-assembled monolayer, closer than about twice the corresponding van der Waals distance, alter the microstructure and improve electrical properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Transporting method for adsorbing tower and the adsorbing tower

    International Nuclear Information System (INIS)

    Shimokawa, Nobuhiro.

    1996-01-01

    A cylindrical plastic bag is disposed to the upper surface of an adsorbing tower so as to surround a suspending piece. One opening of the bag is sealed, and other opening is secured in a sealed state to a bag holding portion disposed to glove box at a gate for the adsorbing tower box. The adsorbing tower is transported into the glove box, and after the completion of the operation of the adsorbing tower, the adsorbing tower is taken out in a state that the bag is restricted and sealed at a portion below the adsorbing tower. The bag may be made of a vinyl plastic, the bag holding portion may be a short-cylindrical protrusion, and may have an O-ring groove at the outer surface. Even if the adsorbing tower is heavy, the adsorbing tower can be carried out easily in a state where it is sealed gas tightly. (N.H.)

  9. 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.)

  10. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Weinelt, M.; Nilsson, A.; Wassdahl, N. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  11. 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.

  12. 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.

  13. 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.

  14. Role of adsorbates on current fluctuations in DC field emission

    International Nuclear Information System (INIS)

    Luong, M.; Bonin, B.; Long, H.; Safa, H.

    1996-01-01

    Field emission experiments in DC regime usually show important current fluctuations for a fixed electric field. These fluctuations are attributed to adsorbed layers (molecules or atoms), liable to affect the work function, height and shape of the potential barrier binding the electron in the metal. The role of these adsorbed species is investigated by showing that the field emission from a well desorbed sample is stable and reproducible and by comparing the emission from the same sample before and after desorption. (author)

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. The state of physically adsorbed substances in microporous adsorbents

    International Nuclear Information System (INIS)

    Fomkin, A.A.

    1987-01-01

    Xe, Kr, Ar, CF 3 Cl, CH 4 adsorption in NaX microporous zeolite of 0.98 Na 2 OxAl 2 O 3 x2.36SiO 2 x0.02H 2 O is studied. Some properties of adsorbates (density, coefficients of expansion, enthalpy, heat capacity) are determined and discussed. The adsorbate in the microporous adsorbent is shown to be a particular state of a substance. Liniarity of adsorption isosteres and sharp changes during isosteric heat capacity of the adsorbate points to the fact that in microporous adsorbents phase transformations of the second type are possible

  20. 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.

  1. Orientational epitaxy in adsorbed monolayers

    International Nuclear Information System (INIS)

    Novaco, A.D.; McTague, J.P.

    1977-01-01

    The ground state for adsorbed monolayers on crystalline substrates is shown to involve a definite relative orientation of the substrate and adsorbate crystal axes, even when the relative lattice parameters are incommensurate. The rotation angle which defines the structure of the monolayer-substrate system is determined by the competition between adsorbate-substrate and adsorbate-adsorbate energy terms, and is generally not a symmetry angle. Numerical predictions are presented for the rare gas-graphite systems, whose interaction potentials are rather well known. Recent LEED data for some of these systems appear to corroborate these predictions

  2. 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.

  3. Zeolites as alcohol adsorbents from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Cekova Blagica

    2006-01-01

    Full Text Available The potential usage of zeolites as adsorbents for the removal of organic molecules from water was investigated in a series of experiments with aqueous solutions of lower alcohols. This could represent a simple solution to the problem of cleaning up industrial wastewater as well as recovering valuable chemicals at relatively low costs. Adsorption isotherms of the Langmuir type were applied, and calculations showed that the amount of propanol adsorbed on silicalite corresponded to approximately 70% of the pore volume. The adsorption process is simple, and recovery of the more concentrated products is easily done by heat treatment and/or at lowered pressures. Adsorption experiments with aqueous acetone showed that silicalite had approximately the same adsorption capacity for acetone as for n-propanol. Heats of adsorption were determined calorimetrically.

  4. Manganese Catalyzed C–H Halogenation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wei; Groves, John T.

    2015-06-16

    The remarkable aliphatic C–H hydroxylations catalyzed by the heme-containing enzyme, cytochrome P450, have attracted sustained attention for more than four decades. The effectiveness of P450 enzymes as highly selective biocatalysts for a wide range of oxygenation reactions of complex substrates has driven chemists to develop synthetic metalloporphyrin model compounds that mimic P450 reactivity. Among various known metalloporphyrins, manganese derivatives have received considerable attention since they have been shown to be versatile and powerful mediators for alkane hydroxylation and olefin epoxidation. Mechanistic studies have shown that the key intermediates of the manganese porphyrin-catalyzed oxygenation reactions include oxo- and dioxomanganese(V) species that transfer an oxygen atom to the substrate through a hydrogen abstraction/oxygen recombination pathway known as the oxygen rebound mechanism. Application of manganese porphyrins has been largely restricted to catalysis of oxygenation reactions until recently, however, due to ultrafast oxygen transfer rates. In this Account, we discuss recently developed carbon–halogen bond formation, including fluorination reactions catalyzed by manganese porphyrins and related salen species. We found that biphasic sodium hypochlorite/manganese porphyrin systems can efficiently and selectively convert even unactivated aliphatic C–H bonds to C–Cl bonds. An understanding of this novel reactivity derived from results obtained for the oxidation of the mechanistically diagnostic substrate and radical clock, norcarane. Significantly, the oxygen rebound rate in Mn-mediated hydroxylation is highly correlated with the nature of the trans-axial ligands bound to the manganese center (L–MnV$=$O). Based on the ability of fluoride ion to decelerate the oxygen rebound step, we envisaged that a relatively long-lived substrate radical could be trapped by a Mn–F fluorine source, effecting carbon–fluorine bond

  5. 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.

  6. 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.

  7. 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

  8. High performance Mo adsorbent PZC

    Energy Technology Data Exchange (ETDEWEB)

    Anon,

    1998-10-01

    We have developed Mo adsorbents for natural Mo(n, {gamma}){sup 99}Mo-{sup 99m}Tc generator. Among them, we called the highest performance adsorbent PZC that could adsorb about 250 mg-Mo/g. In this report, we will show the structure, adsorption mechanism of Mo, and the other useful properties of PZC when you carry out the examination of Mo adsorption and elution of {sup 99m}Tc. (author)

  9. Kinetics of conformational changes of fibronectin adsorbed onto model surfaces.

    Science.gov (United States)

    Baujard-Lamotte, L; Noinville, S; Goubard, F; Marque, P; Pauthe, E

    2008-05-01

    Fibronectin (FN), a large glycoprotein found in body fluids and in the extracellular matrix, plays a key role in numerous cellular behaviours. We investigate FN adsorption onto hydrophilic bare silica and hydrophobic polystyrene (PS) surfaces using Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) in aqueous medium. Adsorption kinetics using different bulk concentrations of FN were followed for 2h and the surface density of adsorbed FN and its time-dependent conformational changes were determined. When adsorption occurs onto the hydrophilic surface, FN molecules keep their native conformation independent of the adsorption conditions, but the amount of adsorbed FN increases with time and the bulk concentration. Although the protein surface density is the same on the hydrophobic PS surface, this has a strong impact on the average conformation of the adsorbed FN layer. Indeed, interfacial hydration changes induced by adsorption onto the hydrophobic surface lead to a decrease in unhydrated beta-sheet content and cause an increase in hydrated beta-strand and hydrated random domain content of adsorbed FN. This conformational change is mainly dependent on the bulk concentration. Indeed, at low bulk concentrations, the secondary structures of adsorbed FN molecules undergo strong unfolding, allowing an extended and hydrated conformation of the protein. At high bulk concentrations, the molecular packing reduces the unfolding of the stereoregular structures of the FN molecules, preventing stronger spreading of the protein.

  10. Positronium chemistry in porous adsorbents

    International Nuclear Information System (INIS)

    Foti, G.; Nagy, L.G.; Moravcsik, G.; Schay, G.

    1981-01-01

    Kinetic studies on the annihilation of orthopositronium in porous adsorbents have been performed using lifetime spectroscopy. The positron source applied was 22 Na with 0.2 MBq activity. The adsorbents investigated were silica gels of different particle size and pore structure. The appearance of the long-lived component in the lifetime spectra can be explained by the diffusion of the orthopositronium into the pores affected by the particle size and the pore size of the adsorbent, the coverage on it and the chemical nature of the adsorbate. The long-term aim of the work is to determine and to explain these effects. (author)

  11. 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.

  12. 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.

  13. Characterisation of lignite as an industrial adsorbent

    Energy Technology Data Exchange (ETDEWEB)

    Ying Qi; Andrew F.A. Hoadley; Alan L. Chaffee; Gil Garnier [Monash University, Clayton, Vic. (Australia). Department of Chemical Engineering

    2011-04-15

    An alternative use of the abundant and inexpensive lignite (also known as brown coal) as an industrial adsorbent has been characterised. The adsorptive properties of two Victorian lignite without any pre-treatment were investigated using the cationic methylene blue dye as a model compound in aqueous solutions. Two commercial activated carbon products were also studied for comparison. The adsorption equilibrium of the four adsorbents was better described by the Langmuir isotherm model than the Freundlich model. The adsorption capacities of the two untreated lignite adsorbents, Loy Yang and Yallourn, calculated using Langmuir isotherms were 286 and 370 mg/g, respectively, higher than a coconut shell-based activated carbon (167 mg/g), but lower than a coal-based activated carbon (435 mg/g). Surface area results suggested that larger micropores and mesopores were important for achieving good methylene blue adsorption by the activated carbons. However, FTIR and cation exchange capacity analyses revealed that, for the lignite, chemical interactions between lignite surface functional groups and methylene blue molecules occurred, thereby augmenting its adsorption capacity. 63 refs., 3 figs., 7 tabs.

  14. 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)

  15. 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.

  16. Adsorbate-induced lifting of substrate relaxation is a general mechanism governing titania surface chemistry.

    Science.gov (United States)

    Silber, David; Kowalski, Piotr M; Traeger, Franziska; Buchholz, Maria; Bebensee, Fabian; Meyer, Bernd; Wöll, Christof

    2016-09-30

    Under ambient conditions, almost all metals are coated by an oxide. These coatings, the result of a chemical reaction, are not passive. Many of them bind, activate and modify adsorbed molecules, processes that are exploited, for example, in heterogeneous catalysis and photochemistry. Here we report an effect of general importance that governs the bonding, structure formation and dissociation of molecules on oxidic substrates. For a specific example, methanol adsorbed on the rutile TiO 2 (110) single crystal surface, we demonstrate by using a combination of experimental and theoretical techniques that strongly bonding adsorbates can lift surface relaxations beyond their adsorption site, which leads to a significant substrate-mediated interaction between adsorbates. The result is a complex superstructure consisting of pairs of methanol molecules and unoccupied adsorption sites. Infrared spectroscopy reveals that the paired methanol molecules remain intact and do not deprotonate on the defect-free terraces of the rutile TiO 2 (110) surface.

  17. The synthesis of a new type adsorbent for the removal of toxic gas by radiation-induced graft polymerization

    International Nuclear Information System (INIS)

    Okamoto, Jiro; Sugo, Takanobu

    1990-01-01

    A new type of adsorbent containing sulfuric acid group for the removal of ammonia gas was synthesized by radiation-induced graft polymerization of styrene onto fibrous and nonwoven type polypropylene followed by sulufonation with chlorosulfonic acid. The rate of the adsorption of ammonia gas by H-type adsorbent is independent of the ion-exchange capacity. The amount of ammonia gas adsorbed by the chemical adsorption was dependent on the ion-exchange capacity of H-type fibrous adsorbent and was kept constant value in spite of the equilibrium pressure of ammonia gas. Cu(II)- and Ni(II)-types fibrous adsorbent were prepared by the ion exchange reaction of Na-type fibrous adsorbent with metal nitrate solutions. Although, the rate of adsorption of ammonia gas by metal-type fibrous adsorbent is lower than that of H-type adsorbent, the amount of ammonia gas adsorbed increases compared to H-type adsorbent with the same ion exchange capacity. It was related to the highest coordination number of metal ion. The ratio of the number of ammonia molecules adsorbed chemically and the number of metal ion adsorbed in fibrous adsorbent was 4 for Cu-type and 6 for Ni-type fibrous adsorbent, respectively. (author)

  18. Irradiation Degradation of Adsorbents for Minor Actinides Recovery

    International Nuclear Information System (INIS)

    Watanabe, S.; Sano, Y.; Kofuji, H.; Takeuchi, M.; Koizumi, T.

    2015-01-01

    Extraction chromatography is one of the promising technologies for minor actinides (MA: Am and Cm) recovery from high-level liquid waste. The degradation behaviour of the organic species in the adsorbents under radiation exposure is important to discuss the safety and durability of the adsorbent in the extraction chromatography process. In this study, gamma-ray irradiation experiments on TODGA/SiO 2 -P adsorbent were carried out to investigate the degradation products from radiolysis of the adsorbent. The degraded organic species eluted from the adsorbent and those remaining inside the adsorbent were thoroughly identified by GC/MS, FT-IR and NMR analyses. The species suspected as hydrolysis products of TODGA were mainly detected from the analyses. Since some radicals such as.H or.OH are generated by the gamma-ray irradiation on water molecules, it was discussed that the radicals products from radiolysis of HNO 3 solution are related to the degradation reaction of the extractants. (authors)

  19. 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

  20. 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.

  1. Self-assembly of iodine in superfluid helium droplets. Halogen bonds and nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    He, Yunteng; Zhang, Jie; Lei, Lei; Kong, Wei [Department of Chemistry, Oregon State University, Corvallis, OR (United States)

    2017-03-20

    We present evidence of halogen bond in iodine clusters formed in superfluid helium droplets based on results from electron diffraction. Iodine crystals are known to form layered structures with intralayer halogen bonds, with interatomic distances shorter than the sum of the van der Waals radii of the two neighboring atoms. The diffraction profile of dimer dominated clusters embedded in helium droplets reveals an interatomic distance of 3.65 Aa, much closer to the value of 3.5 Aa in iodine crystals than to the van der Waals distance of 4.3 Aa. The profile from larger iodine clusters deviates from a single layer structure; instead, a bi-layer structure qualitatively fits the experimental data. This work highlights the possibility of small halogen bonded iodine clusters, albeit in a perhaps limited environment of superfluid helium droplets. The role of superfluid helium in guiding the trapped molecules into local potential minima awaits further investigation. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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...

  7. Black Sprayable Molecular Adsorber Coating

    Data.gov (United States)

    National Aeronautics and Space Administration — The main objective of this technology project is to develop, optimize, and flight qualify a black version of the molecular adsorber coating and a conductive version...

  8. 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.

  9. 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.

  10. [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.

  11. Distribution of adsorbed molecules in electronic nose sensors

    DEFF Research Database (Denmark)

    Swann, M.J.; Glidle, A.; Gadegaard, Nikolaj

    2000-01-01

    Neutron reflectivity measurements of thin films of electropolymerised poly(pyrrole) show that swelling of these insoluble polymers does occur following vapour adsorption. The variation in swelling found for different vapours is correlated with corresponding changes in polymer conductivity and mass...

  12. Formation and decomposition of astatine molecules

    International Nuclear Information System (INIS)

    Takahashi, Naruto; Ishikuro, Mituhiro; Baba Hiroshi

    1989-01-01

    A method determining the boiling points of elementary astatine and astatine iodide has been developed (K. Otozai and N. Takahashi, Radio. Chim. Acta 31, (1982) 201). Further, it was concluded from the simple rule among the boiling point of elementary halogens and interhalogen compounds that elementary astatine might exist in diatomic molecules as the other halogens. In the present work the reaction mechanisms of elementary astatine with radioactive iodine and organic solvents were studied by means of radiogaschromatography in order to obtain further experimental evidences for diatomic astaine molecules. The following conclusions were obtained by the analysis of reaction kinetics. Two astatine atoms are lost from the elementary astatine fraction per each radioactive decay of astatine. The astatine radical or hot atom liberated by the decay of the complementary astatine atom immediately reacts with iodine or organic solvents. Thus formed astatine compounds decompose in turn due to the decay of astatine

  13. 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.

  14. Quantitative relationship between adsorbed amount of solute and solvent composition

    International Nuclear Information System (INIS)

    Wang Yan; Geng Xindu; Zebolsky, Don M.

    2003-01-01

    A new adsorption isotherm that relates the amount of solute adsorbed to the solvent concentration is proposed. The new equation is derived from Geng and Shi's stoichiometric displacement model for adsorption (SDM-A). The obtained equation may be simplified to an expression containing two parameters. The equation with two parameters, valid for low concentrations of solute, is a logarithmically linear relationship. The intercept contains a thermodynamic equilibrium constant of the solute displacing solvent from the adsorbent. The slope is the negative value of the stoichiometric displacement parameter (Z), the average total number of solvent molecules displaced from an active site on the adsorbent and from the solute. Tests with a homologous series of aromatic alcohols by frontal analysis in reversed phase liquid chromatography demonstrate that experimental results fit the equation well

  15. 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)

  16. 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.

  17. Transport through a Single Octanethiol Molecule

    NARCIS (Netherlands)

    Kockmann, D.; Poelsema, Bene; Zandvliet, Henricus J.W.

    2009-01-01

    Octanethiol molecules adsorbed on Pt chains are studied with scanning tunneling microscopy and spectroscopy at 77 K. The head of the octanethiol binds to a Pt atom and the tail is lying flat down on the chain. Open-loop current time traces reveal that the molecule wags its tail and attaches to the

  18. Controlled contact to a C-60 molecule

    DEFF Research Database (Denmark)

    Neel, N.; Kröger, J.; Limot, L.

    2007-01-01

    The tip of a low-temperature scanning tunneling microscope is approached towards a C-60 molecule adsorbed at a pentagon-hexagon bond on Cu(100) to form a tip-molecule contact. The conductance rapidly increases to approximate to 0.25 conductance quanta in the transition region from tunneling to co...

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Krypton retention on solid adsorbents

    International Nuclear Information System (INIS)

    Monson, P.R. Jr.

    1980-01-01

    Radioactive krypton-85 is released to the atmosphere in the off-gas from nuclear reprocessing plants. Three main methods have been suggested for removal of krypton from off-gas streams: cryogenic distillation; fluorocarbon absorption; and adsorption on solid sorbents. Use of solid adsorbents is the least developed of these methods, but offers the potential advantages of enhanced safety and lower operating costs. An experimental laboratory program was developed that will be used to investigate systematically many solid adsorbents (such as zeolites, i.e., mordenites) for trapping krypton in air. The objective of this investigation is to find an adsorbent that is more economical than silver-exchanged mordenite. Various physical and chemical characteristics such as adsorption isotherms, decontamination factors, co-adsorption, regeneration, and the mechanism and kinetics of noble gas adsorption were used to characterize the adsorbents. In the experimental program, a gas chromatograph using a helium ionization detector was used to measure the krypton in air before and after the adsorbent bed. This method can determine directly decontamination factors greater than 100

  4. The condensation of water on adsorbed viruses.

    Science.gov (United States)

    Alonso, José María; Tatti, Francesco; Chuvilin, Andrey; Mam, Keriya; Ondarçuhu, Thierry; Bittner, Alexander M

    2013-11-26

    The wetting and dewetting behavior of biological nanostructures and to a greater degree single molecules is not well-known even though their contact with water is the basis for all biology. Here, we show that environmental electron microscopy (EM) can be applied as a means of imaging the condensation of water onto viruses. We captured the formation of submicrometer water droplets and filaments on single viral particles by environmental EM and by environmental transmission EM. The condensate structures are compatible with capillary condensation between adsorbed virus particles and with known droplet shapes on patterned surfaces. Our results confirm that such droplets exist down to condensation/evaporation cycle as expected from their stability in air and water. Moreover we developed procedures that overcome problems of beam damage and of resolving structures with a low atomic number.

  5. 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

  6. 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

  7. Krypton retention on solid adsorbents

    International Nuclear Information System (INIS)

    Monson, P.R. Jr.

    1982-01-01

    An experimental laboratory program was conducted to develop economical solid adsorbents for the retention of krypton from a dissolver off-gas stream. The study indicates that a solid adsorbent system is feasible and competitive with other developing systems which utilize fluorocarbon absorption nd cryogenic distillation. This technology may have potential applications not only in nuclear fuel reprocessing plants, but also in nuclear reactors and in environmental monitoring. Of the 13 prospective adsorbents evaluated with respect to adsorption capacity and cost, the commercially available hydrogen mordenite was the most cost-effective material at subambient temperatures (-40 0 to -80 0 C). Silver mordenite has a higher capacity for krypton retention, but is 50 times more expensive than hydrogen mordenite

  8. Membrane adsorber for endotoxin removal

    Directory of Open Access Journals (Sweden)

    Karina Moita de Almeida

    Full Text Available ABSTRACT The surface of flat-sheet nylon membranes was modified using bisoxirane as the spacer and polyvinyl alcohol as the coating polymer. The amino acid histidine was explored as a ligand for endotoxins, aiming at its application for endotoxin removal from aqueous solutions. Characterization of the membrane adsorber, analysis of the depyrogenation procedures and the evaluation of endotoxin removal efficiency in static mode are discussed. Ligand density of the membranes was around 7 mg/g dry membrane, allowing removal of up to 65% of the endotoxins. The performance of the membrane adsorber prepared using nylon coated with polyvinyl alcohol and containing histidine as the ligand proved superior to other membrane adsorbers reported in the literature. The lack of endotoxin adsorption on nylon membranes without histidine confirmed that endotoxin removal was due to the presence of the ligand at the membrane surface. Modified membranes were highly stable, exhibiting a lifespan of approximately thirty months.

  9. Browns Ferry charcoal adsorber incident

    International Nuclear Information System (INIS)

    Mays, G.T.

    1979-01-01

    The article reviews the temperature excursion in the charcoal adsorber beds of the Browns Ferry Unit 3 off-gas system that occurred on July 17, 1977. Significant temperature increases were experienced in the charcoal adsorber beds when charcoal fines were ignited by the ignition of a combustible mixture of hydrogen and oxygen in the off-gas system. The Browns Ferry off-gas system is described, and events leading up to and surrounding the incident are discussed. The follow-up investigation by Tennessee Valley Authority and General Electric Company personnel and their recommendations for system and operational modifications are summarized

  10. Krypton retention on solid adsorbents

    International Nuclear Information System (INIS)

    Monson, P.R. Jr.

    1981-08-01

    Over a dozen prospective adsorbents for krypton were studied and evaluated with respect to adsorption capacity and cost for dissolver off-gas streams from nuclear reprocessing plants. Results show that, at subambient temperature (-40 0 to -80 0 C), the commercially available hydrogen mordenite has sufficient adsorptive capacity to be the most cost-effective material studied. Silver mordenite has a higher capacity for krypton retention, but is 50 times more expensive than hydrogen mordenite. The results indicate that a solid adsorbent system is feasible and competitive with other developing systems whih utilize fluorocarbon absorption and cryogenic distillation

  11. Radiolysis of alanine adsorbed in a clay mineral

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar-Ovando, Ellen Y.; Negron-Mendoza, Alicia [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico (UNAM), Circuito Exterior s/n, Ciudad Universitaria, Apartado Postal 70-543, Deleg. Coyoacan, C.P. 04510 (Mexico)

    2013-07-03

    Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically {gamma}-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine.

  12. Radiolysis of alanine adsorbed in a clay mineral

    International Nuclear Information System (INIS)

    Aguilar-Ovando, Ellen Y.; Negrón-Mendoza, Alicia

    2013-01-01

    Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically γ-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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...

  18. 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.

  19. Graphene symmetry-breaking with molecular adsorbates: modeling and experiment

    Science.gov (United States)

    Groce, M. A.; Hawkins, M. K.; Wang, Y. L.; Cullen, W. G.; Einstein, T. L.

    2012-02-01

    Graphene's structure and electronic properties provide a framework for understanding molecule-substrate interactions and developing techniques for band gap engineering. Controlled deposition of molecular adsorbates can create superlattices which break the degeneracy of graphene's two-atom unit cell, opening a band gap. We simulate scanning tunneling microscopy and spectroscopy measurements for a variety of organic molecule/graphene systems, including pyridine, trimesic acid, and isonicotinic acid, based on density functional theory calculations using VASP. We also compare our simulations to ultra-high vacuum STM and STS results.

  20. Iodine and fluorine removal of the water using two synthetic adsorbents of great fixation capacity

    International Nuclear Information System (INIS)

    Neri G, M.; Badillo A, V. E.

    2012-10-01

    In this work is studied the affinity of two synthetic adsorbents of great fixation capacity, the alumina and the hydroxyapatite, as alternative for the removal of two halogens, iodine and fluorine of the water; the first of importance in the radioactive wastes management and the second of interest in public health. This study was carried out applying the technique of radioactive tracers, with 131 I and the radionuclide 18 F (it produced in the unit PET-cyclotron of the UNAM). The affinity of the synthetic adsorbents for the halogens is expressed in terms of the distribution coefficient and of the retention percent in function of the solution ph. The results obtained for the iodine and fluorine in the synthetic solids are markedly different; in the case of the iodine, the retention is worthless in the whole interval of studied ph while for the fluorine high distribution coefficient and fixation percentages are presented of until 100%. Also for the fluorine in hydroxyapatite high distribution coefficients and superiors are obtained in relation to those that are obtained in the alumina. In both solids the fluorine retention diminishes as the ph of the solution increases, what shows the competition with the hydroxyl ions for the active places in surface. (Author)

  1. High resolution spectroscopy of dissociating molecules: Final report, December 15, 1986-October 14, 1987

    International Nuclear Information System (INIS)

    Janda, K.C.

    1988-01-01

    The goal of this project has been to study the structure and dynamics of rare gas-halogen van der Waals molecules. These molecules are important because they provide the only chemical dynamics problem for which precise state-to-state dynamics can be determined by both experiment and full, three-dimensional quantum mechanics theory

  2. Excitation and dissociation of molecules by low-energy (0-15 eV) electrons

    International Nuclear Information System (INIS)

    Verhaart, G.J.

    1980-01-01

    The author deals with excitation and dissociation processes which result from the interaction between low-energy (0.15 eV) electrons and molecules. Low-energy electron-impact spectroscopy is used to gain a better knowledge of the electronic structure of halomethanes, ethylene and some of its halogen substituted derivatives, and some more complex organic molecules. (Auth.)

  3. Bicarbonate Elution of Uranium from Amidoxime-Based Polymer Adsorbents for Sequestering Uranium from Seawater

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Horng-Bin [Department of Chemistry, University of Idaho, Moscow, Idaho 83844 USA; Wai, Chien M. [Department of Chemistry, University of Idaho, Moscow, Idaho 83844 USA; Kuo, Li-Jung [Pacific Northwest National Laboratory, Marine Sciences Laboratory, Sequim, Washington 98382 USA; Gill, Gary [Pacific Northwest National Laboratory, Marine Sciences Laboratory, Sequim, Washington 98382 USA; Tian, Guoxin [Lawrence Berkeley National Laboratory, Berkeley, California 94720 USA; Rao, Linfeng [Lawrence Berkeley National Laboratory, Berkeley, California 94720 USA; Das, Sadananda [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 USA; Mayes, Richard T. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 USA; Janke, Christopher J. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 USA

    2017-05-02

    Uranium adsorbed on amidoxime-based polyethylene fibers in simulated seawater can be quantitatively eluted using 3 M KHCO3 at 40°C. Thermodynamic calculations are in agreement with the experimental observation that at high bicarbonate concentrations (3 M) uranyl ions bound to amidoxime molecules are converted to uranyl tris-carbonato complex in the aqueous solution. The elution process is basically the reverse reaction of the uranium adsorption process which occurs at a very low bicarbonate concentration (~10-3 M) in seawater. In real seawater experiments, the bicarbonate elution is followed by a NaOH treatment to remove natural organic matter adsorbed on the polymer adsorbent. Using the sequential bicarbonate and NaOH elution, the adsorbent is reusable after rinsing with deionized water and the recycled adsorbent shows no loss of uranium loading capacity based on real seawater experiments.

  4. Structures of adsorbed CO on atomically smooth and on stepped sngle crystal surfaces

    International Nuclear Information System (INIS)

    Madey, T.E.; Houston, J.E.

    1980-01-01

    The structures of molecular CO adsorbed on atomically smooth surfaces and on surfaces containing monatomic steps have been studied using the electron stimulated desorption ion angular distribution (ESDIAD) method. For CO adsorbed on the close packed Ru(001) and W(110) surfaces, the dominant bonding mode is via the carbon atom, with the CO molecular axis perpendicular to the plane of the surface. For CO on atomicaly rough Pd(210), and for CO adsorbed at step sites on four different surfaces vicinal to W(110), the axis of the molecule is tilted or inclined away from the normal to the surface. The ESDIAD method, in which ion desorption angles are related to surface bond angles, provides a direct determination of the structures of adsorbed molecules and molecular complexes on surfaces

  5. Heat transfer between adsorbate and laser-heated hot electrons

    International Nuclear Information System (INIS)

    Ueba, H; Persson, B N J

    2008-01-01

    Strong short laser pulses can give rise to a strong increase in the electronic temperature at metal surfaces. Energy transfer from the hot electrons to adsorbed molecules may result in adsorbate reactions, e.g. desorption or diffusion. We point out the limitations of an often used equation to describe the heat transfer process in terms of a friction coupling. We propose a simple theory for the energy transfer between the adsorbate and hot electrons using a newly introduced heat transfer coefficient, which depends on the adsorbate temperature. We calculate the transient adsorbate temperature and the reaction yield for a Morse potential as a function of the laser fluency. The results are compared to those obtained using a conventional heat transfer equation with temperature-independent friction. It is found that our equation of energy (heat) transfer gives a significantly lower adsorbate peak temperature, which results in a large modification of the reaction yield. We also consider the heat transfer between different vibrational modes excited by hot electrons. This mode coupling provides indirect heating of the vibrational temperature in addition to the direct heating by hot electrons. The formula of heat transfer through linear mode-mode coupling of two harmonic oscillators is applied to the recent time-resolved study of carbon monoxide and atomic oxygen hopping on an ultrafast laser-heated Pt(111) surface. It is found that the maximum temperature of the frustrated translation mode can reach high temperatures for hopping, even when direct friction coupling to the hot electrons is not strong enough

  6. Iodine removal adsorbent histories, aging and regeneration

    International Nuclear Information System (INIS)

    Hunt, J.R.; Rankovic, L.; Lubbers, R.; Kovach, J.L.

    1976-01-01

    The experience of efficiency changes with life under various test conditions is described. The adsorbents were periodically removed from both standby and continuously operating systems and tested under various test methods for residual iodine adsorption efficiency. Adsorbent from several conventional ''sampler'' cartridges versus the bulk adsorbent was also tested showing deficiency in the use of cartridge type sampling. Currently required test conditions were found inadequate to follow the aging of the adsorbent because pre-equilibration of the sample acts as a regenerant and the sample is not tested in the ''as is'' condition. The most stringent test was found to be the ambient temperature, high humidity test to follow the aging of the adsorbent. Several methods were evaluated to regenerate used adsorbents; of these high temperature steaming and partial reimpregnation were found to produce adsorbents with near identical properties of freshly prepared adsorbents

  7. 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

  8. 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).

  9. Structure of solid surfaces and of adsorbates by low-energy electron diffraction

    International Nuclear Information System (INIS)

    Somorjai, G.A.

    1977-01-01

    LEED theory has developed to the point where the diffraction beam intensities can be computed using the locations of the surface atoms as the only adjustable parameters. The position of atoms in many clean monatomic solid surfaces and the surface structures of ordered monolayers of adsorbed atoms have been determined this way. Surface crystallography studies are now extended to small hydrocarbon molecules that are adsorbed on metal surfaces. These studies are reviewed

  10. Atomic-Scale Control of Electron Transport through Single Molecules

    DEFF Research Database (Denmark)

    Wang, Y. F.; Kroger, J.; Berndt, R.

    2010-01-01

    Tin-phthalocyanine molecules adsorbed on Ag(111) were contacted with the tip of a cryogenic scanning tunneling microscope. Orders-of-magnitude variations of the single-molecule junction conductance were achieved by controllably dehydrogenating the molecule and by modifying the atomic structure...

  11. Supercritical fluid regeneration of adsorbents

    Science.gov (United States)

    Defilippi, R. P.; Robey, R. J.

    1983-05-01

    The results of a program to perform studies supercritical (fluid) carbon dioxide (SCF CO2) regeneration of adsorbents, using samples of industrial wastewaters from manufacturing pesticides and synthetic solution, and to estimate the economics of the specific wastewater treatment regenerations, based on test data are given. Processing costs for regenerating granular activated carbon GAC) for treating industrial wastewaters depend on stream properties and regeneration throughput.

  12. Molecule nanoweaver

    Science.gov (United States)

    Gerald, II; Rex, E [Brookfield, IL; Klingler, Robert J [Glenview, IL; Rathke, Jerome W [Homer Glen, IL; Diaz, Rocio [Chicago, IL; Vukovic, Lela [Westchester, IL

    2009-03-10

    A method, apparatus, and system for constructing uniform macroscopic films with tailored geometric assemblies of molecules on the nanometer scale. The method, apparatus, and system include providing starting molecules of selected character, applying one or more force fields to the molecules to cause them to order and condense with NMR spectra and images being used to monitor progress in creating the desired geometrical assembly and functionality of molecules that comprise the films.

  13. Adsorption of diclofenac and nimesulide on activated carbon: Statistical physics modeling and effect of adsorbate size

    Science.gov (United States)

    Sellaoui, Lotfi; Mechi, Nesrine; Lima, Éder Cláudio; Dotto, Guilherme Luiz; Ben Lamine, Abdelmottaleb

    2017-10-01

    Based on statistical physics elements, the equilibrium adsorption of diclofenac (DFC) and nimesulide (NM) on activated carbon was analyzed by a multilayer model with saturation. The paper aimed to describe experimentally and theoretically the adsorption process and study the effect of adsorbate size using the model parameters. From numerical simulation, the number of molecules per site showed that the adsorbate molecules (DFC and NM) were mostly anchored in both sides of the pore walls. The receptor sites density increase suggested that additional sites appeared during the process, to participate in DFC and NM adsorption. The description of the adsorption energy behavior indicated that the process was physisorption. Finally, by a model parameters correlation, the size effect of the adsorbate was deduced indicating that the molecule dimension has a negligible effect on the DFC and NM adsorption.

  14. On theory of single-molecule transistor

    International Nuclear Information System (INIS)

    Tran Tien Phuc

    2009-01-01

    The results of the study on single-molecule transistor are mainly investigated in this paper. The structure of constructed single-molecule transistor is similar to a conventional MOSFET. The conductive channel of the transistors is a single-molecule of halogenated benzene derivatives. The chemical simulation software CAChe was used to design and implement for the essential parameter of the molecules utilized as the conductive channel. The GUI of Matlab has been built to design its graphical interface, calculate and plot the output I-V characteristic curves for the transistor. The influence of temperature, length and width of the conductive channel, and gate voltage is considered. As a result, the simulated curves are similar to the traditional MOSFET's. The operating temperature range of the transistors is wider compared with silicon semiconductors. The supply voltage for transistors is only about 1 V. The size of transistors in this research is several nanometers.

  15. Interaction of atomic hydrogen with ethylene adsorbed on nickel films

    International Nuclear Information System (INIS)

    Korchak, V.N.; Tret'yakov, I.I.; Kislyuk, M.U.

    1976-01-01

    The reactivity of ethylene adsorbed on the pure films of nickel at various temperatures was studied with respect to hydrogen atoms generated in the gaseous phase. The experiments were conducted in a glass vacuum apparatus enabling one to obtain the highest vacuum up to 2x20 -10 torr. The catalyst, nickel films, was produced by their deposition onto the walls of the glass reactor at a pressure of the residual gas of 10 -9 torr and a temperature of the walls of 25 deg C. Gas purity was analyzed by the mass spectrometric method. The ethylene adsorbed at the temperatures below 173 deg K reacted readily with the hydrogen atoms to yield ethane. The process ran without practically any activation energy involved and was limited by the attachment of the first hydrogen atom to the ethylene molecule. The efficiency of this interaction was 0.02 of the number of the hydrogen atoms collisions against the surface occupied by the ethylene. The adsorption of the ethylene at room and higher temperatures was accompanied by its disproportioning with the release of the hydrogen into the gaseous phase and a serious destruction of the ethylene molecules adsorbed to produce hydrogen residues interacting with neither molecular nor atomic hydrogen [ru

  16. Distribution of metal and adsorbed guest species in zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Chmelka, B.F.

    1989-12-01

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

  17. Distribution of metal and adsorbed guest species in zeolites

    International Nuclear Information System (INIS)

    Chmelka, B.F.

    1989-12-01

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

  18. Dynamics of copper-phthalocyanine molecules on Au/Ge(001)

    NARCIS (Netherlands)

    Sotthewes, Kai; Heimbuch, Rene; Zandvliet, Henricus J.W.

    2015-01-01

    Spatially resolved current-time scanning tunneling spectroscopy combined with current-distance spectroscopy has been used to characterize the dynamic behavior of copper-phthalocyanine (CuPc) molecules adsorbed on a Au-modified Ge(001) surface. The analyzed CuPc molecules are adsorbed in a “molecular

  19. Kinetics of Adsorbable Organic Halides (AOX Reduction in Laccase-Aided Chlorine Dioxide Bleaching of Bagasse Pulp

    Directory of Open Access Journals (Sweden)

    Xueping Song

    2016-07-01

    Full Text Available This paper presents a kinetic model of the laccase-aided chlorine dioxide bleaching of bagasse pulp. The kinetic model was based on the rate of reduction of adsorbed organic halogen (AOX. The effects of the laccase enzyme dosage, the mediator 1-hydroxybenzotriazole (HBT dosage, and the reaction temperature on the AOX content of the bleaching effluent are discussed. Good fits were obtained for the experimental data obtained from the different laccase enzyme dosages, HBT dosages, and reaction temperatures, indicating the feasibility of the kinetic model as a means of predicting the optimal operation conditions for the laccase-aided chlorine dioxide bleaching of bagasse pulp in the future.

  20. 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.

  1. 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.

  2. 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

  3. 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)

  4. Probing the dynamics of 3He atoms adsorbed on MCM-41 with pulsed NMR

    Science.gov (United States)

    Huan, C.; Masuhara, N.; Adams, J.; Lewkowitz, M.; Sullivan, N. S.

    2018-03-01

    We report measurements of the nuclear spin-spin and spin-lattice relaxation times for 3He adsorbed on MCM-41 for temperatures 0.08 < T < 1.2 K. Deviations from Curie behavior are observed at low temperatures. The relaxation times exhibit a two-component behavior representing the differing dynamics of the mobile quasi-free molecules in the center of the tubes compared to the adsorbed layer on the walls. The amplitudes of the two components provide an accurate measure of the number of fluid-like molecules traveling in the center of the nanotubes.

  5. 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.

  6. 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.

  7. 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.)

  8. 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...

  9. 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.

  10. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 4. Molecule Matters – van der Waals Molecules - History and Some Perspectives on Intermolecular Forces. E Arunan. Feature Article Volume 14 Issue 4 April 2009 pp 346-356 ...

  11. A novel fiber-based adsorbent technology

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, T.A. [Chemica Technologies, Inc., Bend, OR (United States)

    1997-10-01

    In this Phase I Small Business Innovation Research program, Chemica Technologies, Inc. is developing an economical, robust, fiber-based adsorbent technology for removal of heavy metals from contaminated water. The key innovation is the development of regenerable adsorbent fibers and adsorbent fiber cloths that have high capacity and selectivity for heavy metals and are chemically robust. The process has the potential for widespread use at DOE facilities, mining operations, and the chemical process industry.

  12. Equilibrium and heat of adsorption of diethyl phthalate on heterogeneous adsorbents

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, W.M.; Xu, Z.W.; Pan, B.C.; Hong, C.H.; Jia, K.; Jiang, P.J.; Zhang, Q.J.; Pan, B.J. [Nanjing University, Nanjing (China)

    2008-09-15

    Removal of phthalate esters from water has been of considerable concern recently. In the present study, the adsorptive removal performance of diethyl phthalate (DEP) from water was investigated with the aminated polystyrene resin (NDA-101) and oxidized polystyrene resin (NDA-702). In addition, the commercial homogeneous polystyrene resin (XAD-4) and acrylic ester resin (Amberlite XAD-7) as well as coal-based granular activated carbon (AC-750) were chosen for comparison. The corresponding equilibrium isotherms are well described by the Freundlich equation and the adsorption capacities for DEP followed the order NDA-702 > NDA-101 > AC-750 > XAD-4 > XAD-7. Analysis of adsorption mechanisms suggested that these adsorbents spontaneously adsorb DEP molecules driven mainly by enthalpy change, and the adsorption process was derived by multiple adsorbent-adsorbate interactions such as hydrogen bonding, {pi}-{pi} stacking, and micropore filling. The information related to the adsorbent surface heterogeneity and the adsorbate-adsorbate interaction was obtained by Do's model. All the results indicate that heterogeneous resins NDA-702 and NDA-101 have excellent potential as an adsorption material for the removal of DEP from the contaminated water.

  13. Magnetic susceptibility of oxygen adsorbed on the surface of spherical and fibrous activated carbon.

    Directory of Open Access Journals (Sweden)

    Kiyoshi Kawamura

    2009-02-01

    Full Text Available The magnetic susceptibilities of oxygen adsorbed on the surface of bead-shaped activated carbon and activated carbon fibers were evaluated as a function of temperature between 4.2 K and 300 K, and found to exhibit a sharp peak at around 50 K. This implies that the adsorbed oxygen molecules form an antiferromagnetic state. The relation between the susceptibility and the adsorbed mass suggest that the thickness of the adsorbed oxygen is thin enough to consider a two-dimensional structure for bead–shaped activated carbon and carbon fibers across the fiber axis but thick enough to regard it as three-dimensional along the fiber axis. The result is discussed with reference to the study on one-dimensional oxygen array.

  14. Electronic properties of adsorbates and clean surfaces of metals and semiconductors

    International Nuclear Information System (INIS)

    Lecante, J.

    1980-01-01

    This paper surveys recent progress in experimental studies on electronic properties of adsorbates and clean metal surfaces. Electron spectroscopy and particularly angle resolved photoelectron spectroscopy appears to be a very powerful tool to get informations on electronic levels of adsorbates or clean surfaces. Moreover this technique may also give informations about the atomic geometry of the surface. Experimental investigation about surface plasmons, surface states, core level shifts are presented for clean surfaces. As examples of adsorbate covered surfaces two typical cases are chosen: two dimensional band structure and oriented molecules. Finally the photoelectron diffraction may be used for surface structure determination either in the case of an adsorbate or a clean metal surface [fr

  15. Structure of adsorbed monolayers. The surface chemical bond

    International Nuclear Information System (INIS)

    Somorjai, G.A.; Bent, B.E.

    1984-06-01

    This paper attempts to provide a summary of what has been learned about the structure of adsorbed monolayers and about the surface chemical bond from molecular surface science. While the surface chemical bond is less well understood than bonding of molecules in the gas phase or in the solid state, our knowledge of its properties is rapidly accumulating. The information obtained also has great impact on many surface science based technologies, including heterogeneous catalysis and electronic devices. It is hoped that much of the information obtained from studies at solid-gas interfaces can be correlated with molecular behavior at solid-liquid interfaces. 31 references, 42 figures, 1 table

  16. 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)

  17. 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.

  18. 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

  19. 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 ...

  20. 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.

  1. 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.)

  2. Structure formation in bis(terpyridine) derivative adlayers: molecule-substrate versus molecule-molecule interactions.

    Science.gov (United States)

    Hoster, Harry E; Roos, Matthias; Breitruck, Achim; Meier, Christoph; Tonigold, Katrin; Waldmann, Thomas; Ziener, Ulrich; Landfester, Katharina; Behm, R Jürgen

    2007-11-06

    The influence of the substrate and the deposition conditions-vapor deposition versus deposition from solution-on the structures formed upon self-assembly of deposited bis(terpyridine) derivative (2,4'-BTP) monolayers on different hexagonal substrates, including highly oriented pyrolytic graphite (HOPG), Au(111), and (111)-oriented Ag thin films, was investigated by high-resolution scanning tunneling microscopy and by model calculations of the intermolecular energies and the lateral corrugation of the substrate-adsorbate interaction. Similar quasi-quadratic network structures with almost the same lattice constants obtained on all substrates are essentially identical to the optimum configuration expected from an optimization of the adlayer structure with C-H...N-type bridging bonds as a structure-determining factor, which underlines a key role of the intermolecular interactions in adlayer order. Slight distortions from the optimum values to form commensurate adlayer structures on the metal substrates and the preferential orientation of the adlayer with respect to the substrate are attributed to the substrate-adsorbate interactions, specifically, the lateral corrugation in the substrate-adsorbate interaction upon lateral displacement and rotation of the adsorbed BTP molecules. The fact that similar adlayer structures are obtained on HOPG under ultrahigh vacuum conditions (solid|gas interface) and on HOPG in trichlorobenzene (solid|liquid interface) indicates that the intermolecular interactions are not severely affected by the solvent.

  3. Neutron scattering from adsorbed species

    International Nuclear Information System (INIS)

    Shuwang An

    1998-01-01

    Neutron reflection has been used to investigate the structure of layers of water-soluble diblock copolymers poly(2-(dimethylamino)ethyl methacrylate-block-methyl methacrylate (poly(DMAEMA-b-MMA)) (70 mol% DMAEMA, M n = 10k, 80 mol% DMAEMA, M n = 10k, and 70 mol% DMAEMA, M n = 20k) adsorbed at the air-liquid and solid-liquid interfaces. The surface tension behaviour of these copolymers at the air-liquid interface has also been investigated. The study of the structure of layers of poly(DMAEMA-b-MMA) adsorbed at the air-water interface forms the main part of the thesis. The surface structure, the effects of pH and ionic strength, and the effects of composition and molecular weight of the copolymers have been studied systematically. For the 70%-10k copolymer at pH 7.5, the adsorption isotherm shows that there is a surface phase transition. The concentration of copolymer at which the phase transition occurs is close to that at which micellar aggregation in the bulk solution also occurs. At low concentrations (below the CMC), the two blocks of the copolymer are approximately uniformly distributed in the direction normal to the interface and the layer is partially immersed in water. At high concentrations (above the CMC), the adsorbed layer has a cross-sectional structure resembling that expected for a micelle with the majority of the MMA blocks forming the core. The outer layers, comprising predominantly DMAEMA blocks, are not equivalent, being more highly extended on the aqueous side of the interface. The effects of pH and added electrolyte on the structure of layers of the 70%-10k copolymer show that the layered structure is promoted by any changes in the bulk solution that enhance the surface coverage but is inhibited by an increase in the fractional charge on the polyelectrolyte part of the copolymer. The effect of lowering the pH is to increase the positive charge on the weak polyelectrolyte block. Addition of electrolyte generally enhances the amount adsorbed and

  4. Organic adsorbates on metal surfaces. PTCDA and NTCDA on AG(110)

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, Afshin

    2010-02-22

    Polyaromatic molecules functionalized with carboxylic groups have served as model systems for the growth of organic semiconducting films on a large variety of substrates. Most non-reactive substrates allow for a growth mode compatible with the bulk phase of the molecular crystal with two molecules in the unit cell, but some more reactive substrates including Ag(111) and Ag(110) can induce substantial changes in the first monolayer (ML). In the specific case of Ag(110), the adsorbate unit cell of both NTCDA and PTCDA resembles a brickwall structure, with a single molecule in the unit cell. From this finding, it can be concluded that the adsorbate-substrate interaction is stronger than typical inter-molecular binding energies in the respective bulk phases. In the present work, the interactions between small Ag(110) clusters and a single NTCDA or PTCDA molecule are investigated with different ab initio techniques. Four major ingredients contribute to the binding between adsorbate and substrate: Directional bonds between Ag atoms in the topmost layer and the oxygen atoms of the molecule, Pauli repulsion between filled orbitals of molecule and substrate, an attractive van-der-Waals interaction, and a negative net charge on the molecule inducing positive image charges in the substrate, resulting therefore in an attractive Coulomb interaction between these opposite charges. As both Hartree-Fock theory and density functional theory with typical gradient-corrected density functional do not contain any long range correlation energy required for dispersion interactions, we compare these approaches with the fastest numerical technique where the leading term of the van-der-Waals interaction is included, i.e. second order Moeller-Plesset theory (MP2). Both Hartree-Fock and density functional theory result in bended optimized geometries where the adsorbate is interacting mainly via the oxygen atoms, with the core of the molecule repelled from the substrate. Only at the MP2 level

  5. Filter-adsorber aging assessment

    Energy Technology Data Exchange (ETDEWEB)

    Winegardner, W.K. [Pacific Northwest Laboratory, Richland, WA (United States)

    1995-02-01

    An aging assessment of high-efficiency particulate (HEPA) air filters and activated carbon gas adsorption units was performed by the Pacific Northwest Laboratory as part of the U.S. Nuclear Regulatory Commission`s (USNRC) Nuclear Plant Aging Research (NPAR) Program. This evaluation of the general process in which characteristics of these two components gradually change with time or use included the compilation of information concerning failure experience, stressors, aging mechanisms and effects, and inspection, surveillance, and monitoring methods (ISMM). Stressors, the agents or stimuli that can produce aging degradation, include heat, radiation, volatile contaminants, and even normal concentrations of aerosol particles and gasses. In an experimental evaluation of degradation in terms of the tensile breaking strength of aged filter media specimens, over forty percent of the samples did not meet specifications for new material. Chemical and physical reactions can gradually embrittle sealants and gaskets as well as filter media. Mechanisms that can lead to impaired adsorber performance are associated with the loss of potentially available active sites as a result of the exposure of the carbon to airborne moisture or volatile organic compounds. Inspection, surveillance, and monitoring methods have been established to observe filter pressure drop buildup, check HEPA filters and adsorbers for bypass, and determine the retention effectiveness of aged carbon. These evaluations of installed filters do not reveal degradation in terms of reduced media strength but that under normal conditions aged media can continue to effectively retain particles. However, this degradation may be important when considering the likelihood of moisture, steam, and higher particle loadings during severe accidents and the fact it is probable that the filters have been in use for an extended period.

  6. 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.

  7. Miscibility and interaction between 1-alkanol and short-chain phosphocholine in the adsorbed film and micelles.

    Science.gov (United States)

    Takajo, Yuichi; Matsuki, Hitoshi; Kaneshina, Shoji; Aratono, Makoto; Yamanaka, Michio

    2007-09-01

    The miscibility and interaction of 1-hexanol (C6OH) and 1-heptanol (C7OH) with 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) in the adsorbed films and micelles were investigated by measuring the surface tension of aqueous C6OH-DHPC and aqueous C7OH-DHPC solutions. The surface density, the mean molecular area, the composition of the adsorbed film, and the excess Gibbs energy of adsorption g(H,E), were estimated. Further, the critical micelle concentration of the mixtures was determined from the surface tension versus molality curves; the micellar composition was calculated. The miscibility of the 1-alkanols and DHPC molecules in the adsorbed film and micelles was examined using the phase diagram of adsorption (PDA) and that of micellization (PDM). The PDA and the composition dependence of g(H,E) indicated the non-ideal mixing of the 1-alkanols and DHPC molecules due to the attractive interaction between the molecules in the adsorbed film, while the PDM indicated that the 1-alkanol molecules were not incorporated in the micelles within DHPC rich region. The dependence of the mean molecular area of the mixtures on the surface composition suggested that the packing property of the adsorbed film depends on the chain length of 1-alkanol: C6OH expands the DHPC adsorbed film more than C7OH.

  8. 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.

  9. Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent

    Energy Technology Data Exchange (ETDEWEB)

    Janke, Chris [ORNL; Yatsandra, Oyola [ORNL; Mayes, Richard [ORNL; none,; Gill, Gary [PNNL; Li-Jung, Kuo [PNNL; Wood, Jordana [PNNL; Sadananda, Das [ORNL

    2014-04-30

    ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.

  10. Atkins' molecules

    CERN Document Server

    Atkins, Peters

    2003-01-01

    Originally published in 2003, this is the second edition of a title that was called 'the most beautiful chemistry book ever written'. In it, we see the molecules responsible for the experiences of our everyday life - including fabrics, drugs, plastics, explosives, detergents, fragrances, tastes, and sex. With engaging prose Peter Atkins gives a non-technical account of an incredible range of aspects of the world around us, showing unexpected connections, and giving an insight into how this amazing world can be understood in terms of the atoms and molecules from which it is built. The second edition includes dozens of extra molecules, graphical presentation, and an even more accessible and enthralling account of the molecules themselves.

  11. Interstellar Molecules

    Science.gov (United States)

    Solomon, Philip M.

    1973-01-01

    Radioastronomy reveals that clouds between the stars, once believed to consist of simple atoms, contain molecules as complex as seven atoms and may be the most massive objects in our Galaxy. (Author/DF)

  12. Theoretical and experimental study of the vibrational excitations in ethane monolayers adsorbed on graphite (0001) surfaces

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Taub, H.

    1987-01-01

    The collective vibrational excitations of two different crystalline monolayer phases of ethane (C2H6) adsorbed on the graphite (0001) surface have been investigated theoretically and experimentally. The monolayer phases studied are the commensurate 7/8 ×4 structure in which the ethane molecules lie...

  13. Thermodynamics of gas adsorption on solid adsorbents

    International Nuclear Information System (INIS)

    Budrugeac, P.

    1979-01-01

    Starting with several hypotheses about the adsorbtion system and the adsorption phenomenon, a thermodynamic treatment of gas adsorption on solid adsorbants is presented. The relationships for determination from isotherms and calorimetric data of thermodynamic functions are derived. The problem of the phase changes in adsorbed layer is discussed. (author)

  14. Infrared spectroscopic and voltammetric study of adsorbed CO on stepped surfaces of copper monocrystalline electrodes

    International Nuclear Information System (INIS)

    Koga, O.; Teruya, S.; Matsuda, K.; Minami, M.; Hoshi, N.; Hori, Y.

    2005-01-01

    Voltammetric and infrared (IR) spectroscopic measurements were carried out to study adsorbed CO on two series of copper single crystal electrodes n(111)-(111) and n(111)-(100) in 0.1M KH 2 PO 4 +0.1M K 2 HPO 4 at 0 o C. Reversible voltammetric waves were observed below -0.55V versus SHE for adsorption of CO which displaces preadsorbed phosphate anions. The electric charge of the redox waves is proportional to the step atom density for both single crystal series. This fact indicates that phosphate anions are specifically adsorbed on the step sites below -0.55V versus SHE. Voltammetric measurements indicated that (111) terrace of Cu is covered with adsorbed CO below -0.5V versus SHE. Nevertheless, no IR absorption band of adsorbed CO is detected from (111) terrace. Presence of adsorbed CO on (111) terrace is presumed which is not visible by the potential difference spectroscopy used in the present work. IR spectroscopic measurements showed that CO is reversibly adsorbed with an on-top manner on copper single crystal electrodes of n(111)-(111) and n(111)-(100) with approximately same wavenumber of C?O stretching vibration of 2070cm -1 . The IR band intensity is proportional to the step atom density. Thus CO is adsorbed on (111) or (100) steps on the single crystal surfaces. An analysis of the IR band intensity suggested that one CO molecule is adsorbed on every two or more Cu step atom of the monocrystalline surface. The spectroscopic data were compared with those reported for uhv system. The C-O stretching wavenumber of adsorbed CO in the electrode-electrolyte system is 30-40cm -1 lower than those in uhv system

  15. The interaction of linear and ring forms of DNA molecules with nanodiamonds synthesized by detonation

    International Nuclear Information System (INIS)

    Purtov, K V; Burakova, L P; Puzyr, A P; Bondar, V S

    2008-01-01

    Nanodiamonds synthesized by detonation have been found not to immobilize the ring form of pUC19 plasmid DNA. Linear pUC19 molecules with blunt ends, prepared by restriction of the initial ring form of pUC19 DNA, and linear 0.25-10 kb DNA fragments are adsorbed on nanodiamonds. The amount of adsorbed linear DNA molecules depends on the size of the molecules and the size of the nanodiamond clusters

  16. Imaging and manipulation of a polar molecule on Ag(111)

    DEFF Research Database (Denmark)

    Lin, R.; Braun, K.F.; Tang, H.

    2001-01-01

    A scanning tunneling microscope (STM) was applied to image and laterally manipulate isolated phosphangulene molecules on Ag(111) at 6 K. Atomic-resolution images clearly revealed three characteristic types of appearances (three-lobed, fish and bump shape) for the adsorbed molecules, which could...

  17. 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.

  18. Probing Electron-Induced Bond Cleavage at the Single-Molecule Level Using DNA Origami Templates

    DEFF Research Database (Denmark)

    Keller, Adrian Clemens; Bald, Ilko; Rotaru, Alexandru

    2012-01-01

    Low-energy electrons (LEEs) play an important role in nanolithography, atmospheric chemistry, and DNA radiation damage. Previously, the cleavage of specific chemical bonds triggered by LEEs has been demonstrated in a variety of small organic molecules such as halogenated benzenes and DNA nucleoba...

  19. Analysis of Adsorbate-Adsorbate and Adsorbate-Adsorbent Interactions to Decode Isosteric Heats of Gas Adsorption.

    Science.gov (United States)

    Madani, S Hadi; Sedghi, Saeid; Biggs, Mark J; Pendleton, Phillip

    2015-12-21

    A qualitative interpretation is proposed to interpret isosteric heats of adsorption by considering contributions from three general classes of interaction energy: fluid-fluid heat, fluid-solid heat, and fluid-high-energy site (HES) heat. Multiple temperature adsorption isotherms are defined for nitrogen, T=(75, 77, 79) K, argon at T=(85, 87, 89) K, and for water and methanol at T=(278, 288, 298) K on a well-characterized polymer-based, activated carbon. Nitrogen and argon are subjected to isosteric heat analyses; their zero filling isosteric heats of adsorption are consistent with slit-pore, adsorption energy enhancement modelling. Water adsorbs entirely via specific interactions, offering decreasing isosteric heat at low pore filling followed by a constant heat slightly in excess of water condensation enthalpy, demonstrating the effects of micropores. Methanol offers both specific adsorption via the alcohol group and non-specific interactions via its methyl group; the isosteric heat increases at low pore filling, indicating the predominance of non-specific interactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Inorganic chemically active adsorbents (ICAAs)

    Energy Technology Data Exchange (ETDEWEB)

    Ally, M.R. [Oak Ridge National Lab., TN (United States); Tavlarides, L.

    1997-10-01

    Oak Ridge National Laboratory (ORNL) researchers are developing a technology that combines metal chelation extraction technology and synthesis chemistry. They begin with a ceramic substrate such as alumina, titanium oxide or silica gel because they provide high surface area, high mechanical strength, and radiolytic stability. One preparation method involves silylation to hydrophobize the surface, followed by chemisorption of a suitable chelation agent using vapor deposition. Another route attaches newly designed chelating agents through covalent bonding by the use of coupling agents. These approaches provide stable and selective, inorganic chemically active adsorbents (ICAAs) tailored for removal of metals. The technology has the following advantages over ion exchange: (1) higher mechanical strength, (2) higher resistance to radiation fields, (3) higher selectivity for the desired metal ion, (4) no cation exchange, (5) reduced or no interference from accompanying anions, (6) faster kinetics, and (7) easy and selective regeneration. Target waste streams include metal-containing groundwater/process wastewater at ORNL`s Y-12 Plant (multiple metals), Savannah River Site (SRS), Rocky Flats (multiple metals), and Hanford; aqueous mixed wastes at Idaho National Engineering Laboratory (INEL); and scrubber water generated at SRS and INEL. Focus Areas that will benefit from this research include Mixed Waste, and Subsurface Contaminants.

  1. Studies of ethylene hydrogenation and of adsorbed C/sub 2/H/sub 4/ and H/sub 2/ on chromia and lanthana catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Khodakov, Y.S.; Makarov, P.A.; Delzer, G.; Minachev, K.M.

    1980-01-01

    Temperature-programed desorption of ethylene or hydrogen adsorbed at -78/sup 0/, -68/sup 0/, and +20/sup 0/C on chromic oxide, a 1:7 chromic oxide/alumina catalyst prepared by impregnation, alumina, and lanthanum oxide pretreated at 400/sup 0/-900/sup 0/C in vacuo showed that ethylene adsorbed on these oxides on three different sites from which it desorbed at -40/sup 0/ to +10/sup 0/C, at 50/sup 0/-100/sup 0/C, and at 350/sup 0/-400/sup 0/C; and that hydrogen adsorbed only on the latter two sites. One preadsorbed ethylene molecule was displaced at room temperature by 16 molecules of carbon monoxide, 79 molecules of carbon dioxide, or 135 molecules of water. Hydrogen was displaced at lower temperature. The nature of the surface sites and of the adsorbed species, and their reactivities are discussed.

  2. sup(60)Co hot atom chemistry of tris(acetylacetonato) cobalt(III) adsorbed on silica gel

    International Nuclear Information System (INIS)

    Nishioji, H.; Sakai, Y.; Tominaga, T.

    1985-01-01

    The sup(60)Co hot atom reactions were studied in tris(acetylacetonato)cobalt(III) adsorbed on silica gel surface. sup(57)Fe Moessbauer spectra of tris(acetylacetonato)iron(III) in the corresponding system were also measured in order to examine the state of dispersion of complex molecules on silica gel. The retention formation processes were discussed in terms of the dependence of sup(60)Co retention on the adsorbed amount (concentration) of cobalt(III) complexes. (author)

  3. Theory and simulation of epitaxial rotation. Light particles adsorbed on graphite

    DEFF Research Database (Denmark)

    Vives, E.; Lindgård, P.-A.

    1993-01-01

    We present a theory and Monte Carlo simulations of adsorbed particles on a corrugated substrate. We have focused on the case of rare gases and light molecules, H-2 and D2, adsorbed on graphite. The competition between the particle-particle and particle-substrate interactions gives rise to frustra...... found a modulated 4 x 4 structure. Energy, structure-factor intensities, peak positions, and epitaxial rotation angles as a function of temperature and coverage have been determined from the simulations. Good agreement with theory and experimental data is found.......We present a theory and Monte Carlo simulations of adsorbed particles on a corrugated substrate. We have focused on the case of rare gases and light molecules, H-2 and D2, adsorbed on graphite. The competition between the particle-particle and particle-substrate interactions gives rise...... between the commensurate and incommensurate phase for the adsorbed systems. From our simulations and our theory, we are, able to understand the gamma phase of D2 as an ordered phase stabilized by disorder. It can be described as a 2q-modulated structure. In agreement with the experiments, we have also...

  4. Adhesion molecules

    CERN Document Server

    Preedy, Victor R

    2016-01-01

    This book covers the structure and classification of adhesion molecules in relation to signaling pathways and gene expression. It discusses immunohistochemical localization, neutrophil migration, and junctional, functional, and inflammatory adhesion molecules in pathologies such as leukocyte decompression sickness and ischemia reperfusion injury. Highlighting the medical applications of current research, chapters cover diabetes, obesity, and metabolic syndrome; hypoxia; kidney disease; smoking, atrial fibrillation, and heart disease, the brain and dementia; and tumor proliferation. Finally, it looks at molecular imaging and bioinformatics, high-throughput technologies, and chemotherapy.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.)

  11. SFG investigation of adsorbed CO and NO on NiO(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Bandara, Athula; Dobashi, Shinsaku; Kubota, Jun; Onda, Ken; Wada, Akihide; Domen, Kazunari; Hirose, Chiaki [Tokyo Inst. of Tech., Yokohama (Japan). Research Lab. of Resources Utilization; Kano, S.S.

    1997-07-01

    Adsorption structures of CO and NO on the NiO(111) film grown on Ni(111) crystal have been investigated by sum frequency generation (SFG) spectroscopy and infrared reflection absorption spectroscopy (IRAS). The CO stretching band of adsorbed CO on NiO(111) was observed at 2144 cm{sup -1} on the SFG spectra for both p- and s-polarized visible light. However, adsorbed NO on NiO(111) was observed at 1805 cm{sup -1} on the SFG spectra only for the p-polarized visible light. The results suggest that the adsorbed CO molecule was tilted from the surface normal but the NO molecule was perpendicular to the surface. These orientations of CO and NO reflect the surface structure of NiO(111) which has (2 x 2)-reconstructed microfacets. Adsorption of CO on Ni(111) instead of NiO(111) was also examined by SFG and IRAS. Absorption bands due to linear and bridged CO were observed at 2076 and 1918 cm{sup -1}, respectively, by IRAS. On the other hand, the linear CO molecules on Ni(111) gave an SFG peak at 2076 cm{sup -1} only for the p-polarized visible light indicating the CO molecules are perpendicular to the surface, and bridged CO molecules did not give any SFG signal. The absence of the bridged CO signal is believed to be due to the smaller Raman tensor of bridged CO. (author)

  12. SFG investigation of adsorbed CO and NO on NiO(111) surface

    International Nuclear Information System (INIS)

    Bandara, Athula; Dobashi, Shinsaku; Kubota, Jun; Onda, Ken; Wada, Akihide; Domen, Kazunari; Hirose, Chiaki; Kano, S.S.

    1997-01-01

    Adsorption structures of CO and NO on the NiO(111) film grown on Ni(111) crystal have been investigated by sum frequency generation (SFG) spectroscopy and infrared reflection absorption spectroscopy (IRAS). The CO stretching band of adsorbed CO on NiO(111) was observed at 2144 cm -1 on the SFG spectra for both p- and s-polarized visible light. However, adsorbed NO on NiO(111) was observed at 1805 cm -1 on the SFG spectra only for the p-polarized visible light. The results suggest that the adsorbed CO molecule was tilted from the surface normal but the NO molecule was perpendicular to the surface. These orientations of CO and NO reflect the surface structure of NiO(111) which has (2 x 2)-reconstructed microfacets. Adsorption of CO on Ni(111) instead of NiO(111) was also examined by SFG and IRAS. Absorption bands due to linear and bridged CO were observed at 2076 and 1918 cm -1 , respectively, by IRAS. On the other hand, the linear CO molecules on Ni(111) gave an SFG peak at 2076 cm -1 only for the p-polarized visible light indicating the CO molecules are perpendicular to the surface, and bridged CO molecules did not give any SFG signal. The absence of the bridged CO signal is believed to be due to the smaller Raman tensor of bridged CO. (author)

  13. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Molecule Matters - Dinitrogen. A G Samuelson J Jabadurai. Volume 16 Issue 12 ... Author Affiliations. A G Samuelson1 J Jabadurai1. Department of Inroganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

  14. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 9. Molecule Matters - A Chromium Compound with a Quintuple Bond. K C Kumara Swamy. Feature Article Volume 11 Issue 9 September 2006 pp 72-75. Fulltext. Click here to view fulltext PDF. Permanent link:

  15. 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.

  16. 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.

  17. 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

  18. Alkali metal adsorbate sputtering by molecular impact

    International Nuclear Information System (INIS)

    Moran, J.P.; Wachman, H.Y.; Trilling, L.

    1974-01-01

    An exploratory study of the sputtering by a krypton molecular beam of rubidium adsorbed at low coverage on a tungsten substrate has been described in a previous paper. An extension of this work is reported now

  19. PERVAPORATION USING ADSORBENT-FILLED MEMBRANES

    Science.gov (United States)

    Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic co...

  20. Chitin Adsorbents for Toxic Metals: A Review

    Directory of Open Access Journals (Sweden)

    Ioannis Anastopoulos

    2017-01-01

    Full Text Available Wastewater treatment is still a critical issue all over the world. Among examined methods for the decontamination of wastewaters, adsorption is a promising, cheap, environmentally friendly and efficient procedure. There are various types of adsorbents that have been used to remove different pollutants such as agricultural waste, compost, nanomaterials, algae, etc., Chitin (poly-β-(1,4-N-acetyl-d-glucosamine is the second most abundant natural biopolymer and it has attracted scientific attention as an inexpensive adsorbent for toxic metals. This review article provides information about the use of chitin as an adsorbent. A list of chitin adsorbents with maximum adsorption capacity and the best isotherm and kinetic fitting models are provided. Moreover, thermodynamic studies, regeneration studies, the mechanism of adsorption and the experimental conditions are also discussed in depth.

  1. Black Sprayable Molecular Adsorber Coating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The main objective of this technology project is to develop, optimize, and flight qualify a black version of the molecular adsorber coating and a conductive version...

  2. Methyl iodide tests on used adsorbents

    International Nuclear Information System (INIS)

    Kovach, J.L.

    1993-01-01

    This paper discusses the history of events leading to the current problems in radioiodine test conditions. These radioiodine tests are performed in the adsorbent media from both safety and non-safety related Nuclear Air Treatment Systems (NATS). The main problem addressed is that currently there are still numerous plant technical specifications for NATS which reference outdated test protocols for the surveillance testing of the radioactive methyl iodide performance of the adsorbents. Recommendations for correcting the test condition problems are presented. 7 refs

  3. Dissolved Air Flotation of arsenic adsorbent particles

    Directory of Open Access Journals (Sweden)

    Mario Enrique Santander Muñoz

    2015-01-01

    Full Text Available The removal of arsenic from synthetic effluent was studied using the adsorbent particle flotation technique (APF and dissolved air flotation (DAF. A sample of an iron mineral was used as adsorbent particles of arsenic, ferric chloride as coagulant, cationic poly-acrylamide (NALCO 9808 as flocculants, and sodium oleate as collector. Adsorption studies to determine the pH influence, contact time, and adsorbent particles concentration on the adsorption of arsenic were carried out along with flotation studies to determine the removal efficiency of adsorbents particles. The results achieved indicate that the adsorption kinetic of arsenic is very rapid and that in range of pH’s from 2 to 7 the adsorption percentages remain constant. The equilibrium conditions were achieved in 60 minutes and about 95% of arsenic was adsorbed when used an adsorbent concentration of 2 g/L and pH 6.3. The maximum adsorption capacity of adsorbent particles was 4.96 mg/g. The mean free energy of adsorption (E was found to be 2.63 kJ/mol, which suggests physisorption. The results of the flotation studies demonstrated that when synthetic effluents with 8.9 mg/L of arsenic were treated under the following experimental conditions; 2 g/L of adsorbent particles, 120 mg/L of Fe(III, 2 mg/L of Nalco 9808, 20 mg/L of sodium oleate, and 40% of recycle ratio in the DAF, it was possible to reach 98% of arsenic removal and 6.3 NTU of residual turbidity in clarified synthetic effluent.

  4. Properties and selection criteria for adsorbents

    International Nuclear Information System (INIS)

    Wirth, H.

    1976-01-01

    The paper gives a survey of the most important industrial adsorbents and of their suitability for different purposes. With special consideration of activated carbon, the properties and characteristic data are discussed which are used for assessing adsorbents. These, among other things, are as follows: specific surface area, pore size distribution, adsorption isotherms, hydrophobic properties, catalytic properties, chemical resistance, heat resistance, particle size and hardness. (orig.) [de

  5. Protein purification using magnetic adsorbent particles

    DEFF Research Database (Denmark)

    Franzreb, M; Siemann-Herzberg, M.; Hobley, Timothy John

    2006-01-01

    The application of functionalised magnetic adsorbent particles in combination with magnetic separation techniques has received considerable attention in recent years. The magnetically responsive nature of such adsorbent particles permits their selective manipulation and separation in the presence...... separations are fast, gentle, scaleable, easily automated, can achieve separations that would be impossible or impractical to achieve by other techniques, and have demonstrated credibility in a wide range of disciplines, including minerals processing, wastewater treatment, molecular biology, cell sorting...

  6. Mesoporous Silica: A Suitable Adsorbent for Amines

    Directory of Open Access Journals (Sweden)

    Abdollahzadeh-Ghom Sara

    2009-01-01

    Full Text Available Abstract Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices.

  7. Self-consistent field theory of polymer-ionic molecule complexation

    OpenAIRE

    Nakamura, Issei; Shi, An-Chang

    2010-01-01

    A self-consistent field theory is developed for polymers that are capable of binding small ionic molecules (adsorbates). The polymer-ionic molecule association is described by Ising-like binding variables, C_(i)^(a)(kΔ)(= 0 or 1), whose average determines the number of adsorbed molecules, nBI. Polymer gelation can occur through polymer-ionic molecule complexation in our model. For polymer-polymer cross-links through the ionic molecules, three types of solutions for nBI are obtained, depending...

  8. 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

  9. 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.

  10. 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

  11. 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)

  12. Photoelectron diffraction studies of small adsorbates on single crystal surfaces

    International Nuclear Information System (INIS)

    Pascal, Mathieu

    2002-01-01

    The structural determination of small molecules adsorbed on single crystal surfaces has been investigated using scanned energy mode photoelectron diffraction (PhD). The experimental PhD data were compared to theoretical models using a simulation program based on multiple scattering calculations. Three adsorption systems have been examined on Ag(110), Cu(110) and Cu(111) crystals. The structure of the (2x1)-O adsorption phase on Ag(110) revealed that the O atoms occupied the long bridge site and are almost co-planar with the top layer of Ag atoms. The best agreement between multiple scattering theory and experiment has been obtained for a missing-row (or equivalently an 'added- row') reconstruction. Alternative buckled-row and unreconstructed surface models can be excluded. The adsorption of the benzoate species on Cu(110) has been found to occur via the carboxylate group. The molecules occupy short bridge sites with the O atoms being slightly displaced from atop sites and are aligned along the close-packed azimuth. The tilt of the molecule with respect to the surface and the degree to which the surface is relaxed have also been investigated. The adsorption of methyl on Cu(111) was studied using either azomethane or methyl iodide to prepare the surface layers. At saturation coverage the preferred adsorption site is the fcc threefold hollow site, whereas at half saturation coverage ∼ 30 % of the methyl species occupy the hop threefold hollow sites. Best agreement between theory and experiment corresponded to a methyl group adsorbed with C 3v symmetry. The height of the C above the surface in a pure methyl layer was 1.66 ± 0.02 A, but was reduced to 1.62 ± 0.02 A in the presence of co-adsorbed iodine, suggesting that iodine increases the strength of adsorption. Iodine was also found to occupy the fee threefold hollow sites with a Cu-l bondlength of 2.61 ± 0.02 A. (author)

  13. Development and characterization of activated hydrochars from orange peels as potential adsorbents for emerging organic contaminants.

    Science.gov (United States)

    Fernandez, M E; Ledesma, B; Román, S; Bonelli, P R; Cukierman, A L

    2015-05-01

    Activated hydrochars obtained from the hydrothermal carbonization of orange peels (Citrus sinensis) followed by various thermochemical processing were assessed as adsorbents for emerging contaminants in water. Thermal activation under flows of CO2 or air as well as chemical activation with phosphoric acid were applied to the hydrochars. Their characteristics were analyzed and related to their ability to uptake three pharmaceuticals (diclofenac sodium, salicylic acid and flurbiprofen) considered as emerging contaminants. The hydrothermal carbonization and subsequent activations promoted substantial chemical transformations which affected the surface properties of the activated hydrochars; they exhibited specific surface areas ranging from 300 to ∼620 m(2)/g. Morphological characterization showed the development of coral-like microspheres dominating the surface of most hydrochars. Their ability to adsorb the three pharmaceuticals selected was found largely dependent on whether the molecules were ionized or in their neutral form and on the porosity developed by the new adsorbents. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Electron-Stimulated Desorption of Positive Ions from Methanol Adsorbed on a Solid Ar Substrate

    Science.gov (United States)

    Kawanowa, H.; Hanatani, K.; Gotoh, Y.; Souda, R.

    Electron-stimulated desorption (ESD) of positive ions from weakly physisorbed molecules has been investigated. From methanol adsorbed on a solid Ar substrate, the protonated cluster ions of the type H+(CH3OH)n (n = 1 - 4) are emitted, together with the fragment ions such as CHn+ (n = 0 - 3), H3O+, CHO+, CH3O+, etc. The yields of these ions are markedly enhanced at the smallest coverage and decay steeply with increasing coverage. Coulomb explosion between valence holes confined in adsorbed nanoclusters is responsible for the enhanced ion yields. Very few ions except for H+ are emitted from a thick layer as well as nanoclusters adsorbed directly on a metal substrate due to the delocalization of valence holes.

  15. Novel Fiber-Based Adsorbent Technology; FINAL

    International Nuclear Information System (INIS)

    Nixon, P.G.; Tsukamoto, T.; Brose, D.J.

    2001-01-01

    The overall of this Department of Energy (DOE) Phase II SBIR program was to develop a new class of highly robust fiber-based adsorbents for recovery of heavy metals from aqueous waste-streams. The fiber-based adsorbents,when commercialized,will be used for clean up metals in aqueous waste-streams emanating from DOE facilities,industry,mining,and groundwater-cleanup operations.The amount of toxic waste released by these streams is of great significance.The U.S.Environment Protection Agency (EPA) reports that in 1990 alone,4.8 billion pounds of toxic chemicals were released into the environment.Of this waste,the metals-containing waste was the second largest contributor,representing 569 million pounds. This report presents the results of the Phase II program,which successfully synthesized noval fiber-based adsorbents for the removal of Group 12 metals(i.e.mercury),Group 14 metals (lead),and Group 10 metals(platinum and palladium) from contaminated groundwater and industrial waste streams.These fiber-based adsorbents are ideally suited for the recovery of metal ions from aqueous waste streams presently not treatable due to the degrading nature of corrosive chemicals or radioactive components in the feed stream. The adsorbents developed in this program rely on chemically resistant and robust carbon fibers and fabrics as supports for metal-ion selective ligands.These adsorbents demonstrate loading capacities and selectivities for metal ions exceeding those of conventional ion-exchange resins.The adsorbents were also used to construct filter modules that demonstrate minimal fouling,minimal compaction,chemical and physical robustness,and regeneration of metal loading capacity without loss of performance

  16. Relationship between centrifugation and drying of sludge and the organic halogens

    Directory of Open Access Journals (Sweden)

    Karel Hrich

    2010-01-01

    Full Text Available This work is focused on determination of adsorbable organic halogens (AOX concentration in the digested sludge from the sewage treatment plant and the losses of this component during dewatering and drying of sludge. Drying of the sludge from wastewater treatment plant is not extended too much in Czech Republic. In this work, the AOX are monitored, because AOX is one of the limits restraining use of the sludge on an agricultural land. Another reason is technological demand for using the sludge in cement processing, because chlorine in AOX can cause decrease in a heat transfer effect in a cement kiln. It is clear from the results that both centrifuged and dried sludge from the sewage treatment plant Brno fulfilled limits for using sludge on agriculture land. They can also be composted, in case they meet other requirements. If not, it is a possibility of co-incineration in cement kiln. In such case, limit for total chlorine including the AOX is required too. This limit was not exceeded. Another aim was to calculate a mass balance of AOX during the centrifugation and drying processes. It was found out, that after centrifugation the main part of AOX remained in the centrifuged sludge (96.4 %. The rest was drawn-off with reject water. 60 % of AOX in the reject water were dissolved compounds. A similar situation occurred during the drying process. More than 99 % of AOX was bound in the dried sludge. The air and vaporised water contained such quantity of AOX, which corresponded with the amount of the dust in the air and the amount of particles of sludge in vaporised water.

  17. Photochemical dynamics of surface oriented molecules

    International Nuclear Information System (INIS)

    Ho, W.

    1992-01-01

    The period 8/01/91-7/31/92 is the first year of a new project titled ''Photochemical Dynamics of Surface Oriented Molecules'', initiated with DOE Support. The main objective of this project is to understand the dynamics of elementary chemical reactions by studying photochemical dynamics of surface-oriented molecules. In addition, the mechanisms of photon-surface interactions need to be elucidated. The strategy is to carry out experiments to measure the translational energy distribution, as a function of the angle from the surface normal, of the photoproducts by time-of-flight (TOF) technique by varying the photon wavelength, intensity, polarization, and pulse duration. By choosing adsorbates with different bonding configuration, the effects of adsorbate orientation on surface photochemical dynamics can be studied

  18. Integrated analysis of halogenated organic pollutants in sub-millilitre volumes of venous and umbilical cord blood sera

    Energy Technology Data Exchange (ETDEWEB)

    Grimalt, Joan O.; Carrizo, Daniel; Otero, Raquel; Vizcaino, Esther [Institute of Environmental Assessment and Water Research (IDAeA-CSIC), Department of Environmental Chemistry, Barcelona, Catalonia (Spain); Howsam, Mike [Universite de Lille 2, Centre Universitaire de Mesure et d' Analyse, Faculte de Pharmacie, Lille (France); Rodrigues de Marchi, Mary Rosa [Institute of Chemistry UNESP, Department of Analytical Chemistry, Araraquara, SP (Brazil)

    2010-03-15

    A rapid, robust and economical method for the analysis of persistent halogenated organic compounds in small volumes of human serum and umbilical cord blood is described. The pollutants studied cover a broad range of molecules of contemporary epidemiological and legislative concern, including polychlorobiphenyls (PCBs), polychlorobenzenes (CBs), hexachlorocyclohexanes (HCHs), DDTs, polychlorostyrenes (PCSs) and polybromodiphenyl ethers (PBDEs). Extraction and clean-up with n-hexane and concentrated sulphuric acid was followed with analysis by gas chromatography coupled to electron capture (GC-ECD) and GC coupled to negative ion chemical ionisation mass spectrometry (GC-NICI-MS). The advantages of this method rest in the broad range of analytes and its simplicity and robustness, while the use of concentrated sulphuric acid extraction/clean-up destroys viruses that may be present in the samples. Small volumes of reference serum between 50 and 1000{mu}L were extracted and the limits of detection/quantification and repeatability were determined. Recoveries of spiked compounds for the extraction of small volumes ({>=}300 {mu}L) of the spiked reference serum were between 90% and 120%. The coefficients of variation of repeatability ranged from 0.1-14%, depending on the compound. Samples of 4-year-old serum and umbilical cord blood (n=73 and 40, respectively) from a population inhabiting a village near a chloro-alkali plant were screened for the above-mentioned halogenated pollutants using this method and the results are briefly described. (orig.)

  19. 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.

  20. 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

  1. Process for producing zeolite adsorbent and process for treating radioactive liquid waste with the zeolite adsorbent

    International Nuclear Information System (INIS)

    Motojima, K.; Kawamura, F.

    1984-01-01

    Zeolite is contacted with an aqueous solution containing at least one of copper, nickel, cobalt, manganese and zinc salts, preferably copper and nickel salts, particularly preferably copper salt, in such a form as sulfate, nitrate, or chloride, thereby adsorbing the metal on the zeolite in its pores by ion exchange, then the zeolite is treated with a water-soluble ferrocyanide compound, for example, potassium ferrocyanide, thereby forming metal ferrocyanide on the zeolite in its pores. Then, the zeolite is subjected to ageing treatment, thereby producing a zeolite adsorbent impregnated with metal ferrocyanide in the pores of zeolite. The adsorbent can selectively recover cesium with a high percent cesium removal from a radioactive liquid waste containing at least radioactive cesium, for example, a radioactive liquid waste containing cesium and such coexisting ions as sodium, magnesium, calcium and carbonate ions at the same time at a high concentration. The zeolite adsorbent has a stable adsorbability for a prolonged time

  2. Method for modifying trigger level for adsorber regeneration

    Science.gov (United States)

    Ruth, Michael J.; Cunningham, Michael J.

    2010-05-25

    A method for modifying a NO.sub.x adsorber regeneration triggering variable. Engine operating conditions are monitored until the regeneration triggering variable is met. The adsorber is regenerated and the adsorbtion efficiency of the adsorber is subsequently determined. The regeneration triggering variable is modified to correspond with the decline in adsorber efficiency. The adsorber efficiency may be determined using an empirically predetermined set of values or by using a pair of oxygen sensors to determine the oxygen response delay across the sensors.

  3. Adsorbent catalytic nanoparticles and methods of using the same

    Energy Technology Data Exchange (ETDEWEB)

    Slowing, Igor Ivan; Kandel, Kapil

    2017-01-31

    The present invention provides an adsorbent catalytic nanoparticle including a mesoporous silica nanoparticle having at least one adsorbent functional group bound thereto. The adsorbent catalytic nanoparticle also includes at least one catalytic material. In various embodiments, the present invention provides methods of using and making the adsorbent catalytic nanoparticles. In some examples, the adsorbent catalytic nanoparticles can be used to selectively remove fatty acids from feedstocks for biodiesel, and to hydrotreat the separated fatty acids.

  4. From illite/smectite clay to mesoporous silicate adsorbent for efficient removal of chlortetracycline from water.

    Science.gov (United States)

    Wang, Wenbo; Tian, Guangyan; Zong, Li; Zhou, Yanmin; Kang, Yuru; Wang, Qin; Wang, Aiqin

    2017-01-01

    A series of mesoporous silicate adsorbents with superior adsorption performance for hazardous chlortetracycline (CTC) were sucessfully prepared via a facile one-pot hydrothermal reaction using low-cost illite/smectite (IS) clay, sodium silicate and magnesium sulfate as the starting materials. In this process, IS clay was "teared up" and then "rebuilt" as new porous silicate adsorbent with high specific surface area of 363.52m 2 /g (about 8.7 folds higher than that of IS clay) and very negative Zeta potential (-34.5mV). The inert SiOSi (Mg, Al) bonds in crystal framework of IS were broken to form Si(Al) O - groups with good adsorption activity, which greatly increased the adsorption sites served for holding much CTC molecules. Systematic evaluation on adsorption properties reveals the optimal silicate adsorbent can adsorb 408.81mg/g of CTC (only 159.7mg/g for raw IS clay) and remove 99.3% (only 46.5% for raw IS clay) of CTC from 100mg/L initial solution (pH3.51; adsorption temperature 30°C; adsorbent dosage, 3g/L). The adsorption behaviors of CTC onto the adsorbent follows the Langmuir isotherm model, Temkin equation and pseudo second-order kinetic model. The mesopore adsorption, electrostatic attraction and chemical association mainly contribute to the enhanced adsorption properties. As a whole, the high-efficient silicate adsorbent could be candidates to remove CTC from the wastewater with high amounts of CTC. Copyright © 2016. Published by Elsevier B.V.

  5. 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

  6. 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...

  7. Many-body dispersion effects in the binding of adsorbates on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Maurer, Reinhard J. [Department of Chemistry, Yale University, New Haven, Connecticut 06520 (United States); Ruiz, Victor G.; Tkatchenko, Alexandre [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany)

    2015-09-14

    A correct description of electronic exchange and correlation effects for molecules in contact with extended (metal) surfaces is a challenging task for first-principles modeling. In this work, we demonstrate the importance of collective van der Waals dispersion effects beyond the pairwise approximation for organic–inorganic systems on the example of atoms, molecules, and nanostructures adsorbed on metals. We use the recently developed many-body dispersion (MBD) approach in the context of density-functional theory [Tkatchenko et al., Phys. Rev. Lett. 108, 236402 (2012) and Ambrosetti et al., J. Chem. Phys. 140, 18A508 (2014)] and assess its ability to correctly describe the binding of adsorbates on metal surfaces. We briefly review the MBD method and highlight its similarities to quantum-chemical approaches to electron correlation in a quasiparticle picture. In particular, we study the binding properties of xenon, 3,4,9,10-perylene-tetracarboxylic acid, and a graphene sheet adsorbed on the Ag(111) surface. Accounting for MBD effects, we are able to describe changes in the anisotropic polarizability tensor, improve the description of adsorbate vibrations, and correctly capture the adsorbate–surface interaction screening. Comparison to other methods and experiment reveals that inclusion of MBD effects improves adsorption energies and geometries, by reducing the overbinding typically found in pairwise additive dispersion-correction approaches.

  8. Electrochemical Properties of Alkanethiol Monolayers Adsorbed on Nanoporous Au Surfaces

    International Nuclear Information System (INIS)

    Chu, Yeon Yi; Seo, Bora; Kim, Jong Won

    2010-01-01

    We investigated the electrochemical properties of alkanethiol monolayers adsorbed on NPG surfaces by cyclic voltammetry and electrochemical impedance spectroscopy, and the results are compared to those on flat Au surfaces. The reductive desorption of alkanethiols on NPG surfaces is observed in more negative potential regions than that on flat Au surfaces due the stronger S-Au interaction on NPG surfaces. While the electron transfer through alkanethiol monolayers on flat Au surfaces occurs via a tunneling process through the monolayer films, the redox species can permeate through the monolayers on NPG surfaces to transfer the electrons to the Au surfaces. The results presented here will help to elucidate the intrinsic electrochemical properties of alkanethiol monolayers adsorbed on curved Au surfaces, particularly on the surface of AuNPs. Self-assembled monolayers (SAMs) of thiolate molecules on Au surfaces have been the subject of intensive research for the last few decades due to their unique physical and chemical properties. The well-organized surface structures of thiolate SAMs with various end-group functionalities can be further utilized for many applications in biology and nanotechnology. In addition to the practical applications, SAMs of thiolate molecules on Au surfaces also provide unique opportunities to address fundamental issues in surface chemistry such as self-organized surface structures, electron transfer behaviors, and moleculesubstrate interactions. Although there have been numerous reports on the fundamental physical and chemical properties of thiolate SAMs on Au surfaces, most of them were investigated on flat Au surfaces, typically on well-defined Au(111) surfaces

  9. 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.

  10. 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

  11. To bend or not to bend – are heteroatom interactions within conjugated molecules effective in dictating conformation and planarity?

    KAUST Repository

    Conboy, Gary; Spencer, Howard J.; Angioni, Enrico; Kanibolotsky, Alexander L.; Findlay, Neil J.; Coles, Simon J.; Wilson, Claire; Pitak, Mateusz B.; Risko, Chad; Coropceanu, Veaceslav; Bredas, Jean-Luc; Skabara, Peter J.

    2016-01-01

    We consider the roles of heteroatoms (mainly nitrogen, the halogens and the chalcogens) in dictating the conformation of linear conjugated molecules and polymers through non-covalent intramolecular interactions. Whilst hydrogen bonding is a competitive and sometimes more influential interaction, we provide unambiguous evidence that heteroatoms are able to determine the conformation of such materials with reasonable predictability.

  12. To bend or not to bend – are heteroatom interactions within conjugated molecules effective in dictating conformation and planarity?

    KAUST Repository

    Conboy, Gary

    2016-04-26

    We consider the roles of heteroatoms (mainly nitrogen, the halogens and the chalcogens) in dictating the conformation of linear conjugated molecules and polymers through non-covalent intramolecular interactions. Whilst hydrogen bonding is a competitive and sometimes more influential interaction, we provide unambiguous evidence that heteroatoms are able to determine the conformation of such materials with reasonable predictability.

  13. 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

  14. Scanning tunneling microscopy studies of organic monolayers adsorbed on the rhodium(111) crystal surface

    Energy Technology Data Exchange (ETDEWEB)

    Cernota, Paul Davis [Univ. of California, Berkeley, CA (United States)

    1999-08-01

    Scanning Tunneling Microscopy studies were carried out on ordered overlayers on the (111) surface of rhodium. These adsorbates include carbon monoxide (CO), cyclohexane, cyclohexene, 1,4-cyclohexadiene, para-xylene, and meta-xylene. Coadsorbate systems included: CO with ethylidyne, CO with para- and meta-xylene, and para-xylene with meta-xylene. In the case of CO, the structure of the low coverage (2x2) overlayer has been observed. The symmetry of the unit cell in this layer suggests that the CO is adsorbed in the 3-fold hollow sites. There were also two higher coverage surface structures with (√7x√7) unit cells. One of these is composed of trimers of CO and has three CO molecules in each unit cell. The other structure has an additional CO molecule, making a total of four. This extra CO sits on a top site.

  15. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 12. Molecule Matters van der Waals Molecules - Noble Gas Clusters are London Molecules! E Arunan. Feature Article Volume 14 Issue 12 December 2009 pp 1210-1222 ...

  16. 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.

  17. Halogenated 1-Hydroxynaphthalene-2-Carboxanilides Affecting Photosynthetic Electron Transport in Photosystem II

    Directory of Open Access Journals (Sweden)

    Tomas Gonec

    2017-10-01

    Full Text Available Series of seventeen new multihalogenated 1-hydroxynaphthalene-2-carboxanilides was prepared and characterized. All the compounds were tested for their activity related to the inhibition of photosynthetic electron transport (PET in spinach (Spinacia oleracea L. chloroplasts. 1-Hydroxy-N-phenylnaphthalene-2-carboxamides substituted in the anilide part by 3,5-dichloro-, 4-bromo-3-chloro-, 2,5-dibromo- and 3,4,5-trichloro atoms were the most potent PET inhibitors (IC50 = 5.2, 6.7, 7.6 and 8.0 µM, respectively. The inhibitory activity of these compounds depends on the position and the type of halogen substituents, i.e., on lipophilicity and electronic properties of individual substituents of the anilide part of the molecule. Interactions of the studied compounds with chlorophyll a and aromatic amino acids present in pigment-protein complexes mainly in PS II were documented by fluorescence spectroscopy. The section between P680 and plastoquinone QB in the PET chain occurring on the acceptor side of PS II can be suggested as the site of action of the compounds. The structure-activity relationships are discussed.

  18. Analysis of the physical atomic forces between noble gas atoms, alkali ions and halogen ions

    Science.gov (United States)

    Wilson, J. W.; Heinbockel, J. H.; Outlaw, R. A.

    1986-01-01

    The physical forces between atoms and molecules are important in a number of processes of practical importance, including line broadening in radiative processes, gas and crystal properties, adhesion, and thin films. The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base for the dispersion forces is developed from the literature based on evaluations with the harmonic oscillator dispersion model for higher order coefficients. The Zener model of the repulsive core is used in the context of the recent asymptotic wave functions of Handler and Smith; and an effective ionization potential within the Handler and Smith wave functions is defined to analyze the two body potential data of Waldman and Gordon, 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 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.

  19. Theoretical Insight of Physical Adsorption for a Single Component Adsorbent + Adsorbate System: II. The Henry Region

    KAUST Repository

    Chakraborty, Anutosh

    2009-07-07

    The Henry coefficients of a single component adsorbent + adsorbate system are calculated from experimentally measured adsorption isotherm data, from which the heat of adsorption at zero coverage is evaluated. The first part of the papers relates to the development of thermodynamic property surfaces for a single-component adsorbent + adsorbate system1 (Chakraborty, A.; Saha, B. B.; Ng, K. C.; Koyama, S.; Srinivasan, K. Langmuir 2009, 25, 2204). A thermodynamic framework is presented to capture the relationship between the specific surface area (Ai) and the energy factor, and the surface structural and the surface energy heterogeneity distribution factors are analyzed. Using the outlined approach, the maximum possible amount of adsorbate uptake has been evaluated and compared with experimental data. It is found that the adsorbents with higher specific surface areas tend to possess lower heat of adsorption (ΔH°) at the Henry regime. In this paper, we have established the definitive relation between Ai and ΔH° for (i) carbonaceous materials, metal organic frameworks (MOFs), carbon nanotubes, zeolites + hydrogen, and (ii) activated carbons + methane systems. The proposed theoretical framework of At and AH0 provides valuable guides for researchers in developing advanced porous adsorbents for methane and hydrogen uptake. © 2009 American Chemical Society.

  20. Volatile organic compounds adsorption using different types of adsorbent

    Directory of Open Access Journals (Sweden)

    Pimanmes Chanayotha

    2014-09-01

    Full Text Available Adsorbents were synthesized from coconut shell, coal and coke by pyrolysis followed by chemical activation process. These synthesized materials were used as adsorbents in adsorption test to determine the amount of volatile organic compounds (VOCs namely, 2-Hydroxyethyl methacrylate (HEMA, Octamethylcyclotetrasiloxane and Alkanes standard solution (C8-C20. The adsorption capacities of both synthesized adsorbents and commercial grade adsorbents (Carbotrap™ B and Carbotrap™ C were also compared. It was found that adsorbent A402, which was produced from coconut shell, activated with 40% (wt. potassium hydroxide and at activating temperature of 800°C for 1 hr, could adsorb higher amount of both HEMA and Octamethylcyclotetrasiloxane than other synthesized adsorbents. The maximum adsorption capacity of adsorbent A402 in adsorbing HEMA and Octamethylcyclotetrasiloxane were 77.87% and 50.82% respectively. These adsorption capabilities were 79.73% and 70.07% of the adsorption capacity of the commercial adsorbent Carbotrap™ B respectively. All three types of the synthesized adsorbent (A402, C302, C402 showed the capability to adsorb alkanes standard solution through the range of C8-C20 . However, their adsorption capacities were high in a specific range of C10-C11. The result from the isotherm plot was indicated that surface adsorption of synthesized adsorbent was isotherm type I while the surface adsorption of commercial adsorbent was isotherm type III.

  1. Towards a better understanding of the geometrical and orientational aspects of the electronic structure of halogens (F–I) adsorption on graphene

    International Nuclear Information System (INIS)

    Widjaja, Hantarto; Jiang, Zhong-Tao; Altarawneh, Mohammednoor; Yin, Chun-Yang; Goh, Bee-Min; Mondinos, Nicholas; Dlugogorski, Bogdan Z.

    2015-01-01

    Graphical abstract: - Highlights: • Examines the orientation (zigzag, armchair) effects of F/Cl/Br/I-adsorbed graphene. • F cases are site-dependent, while Cl/Br/I cases have minimal orientation dependence. • F is adsorbed to graphene at about three times stronger than Cl/Br/I. • To prompt re-examination of elemental-graphene systems to account for orientation. - Abstract: Adding impurities or doping through adsorption is an effective way to modify the properties of graphene-based materials. The capability of making predictions pertinent to the trends of elemental adsorption on graphene is very instrumental towards a better understanding of the more complex adsorption cases. It also affords useful guidelines for fabricating 2-D graphene materials with novel properties. The electronic structure of elemental adsorption on graphene is affected by side of adsorption (single- or double-sided), site of adsorption (i.e. bridge, hollow or top), and the relative orientation of the adsorbed sites (i.e. zigzag or armchair). In this contribution, we apply density functional theory (DFT) calculations to investigate the electronic structures of halogens (F, Cl, Br, I) adsorbed on graphene at lower concentrations spanning 1:6, 1:8 and 1:18 atomic ratios, in order to elucidate effects of adsorption trends. We demonstrate that adsorption of F is merely site-dependent (top). On the contrary, adsorptions of Cl, Br and I display a minimal dependence towards orientation (i.e. the effects of the deployed supercells). Our findings provide a deeper understanding of the elemental adsorption on graphene in terms of geometry which may aid in reexamining previous studies and producing better predictions for future studies, in which the inclusion of orientation is indispensable.

  2. Adsorbed layers on (111)InAs faces in contact with In-As-Cl-H gas phase, and the possibility of phase transitions in the adsorbed layers

    Science.gov (United States)

    Chernov, A. A.; Ruzaikin, M. P.

    1981-04-01

    Adsorption of various species existing in the In-As-Cl-H CVD gaseous system on both InAs (111) faces is considered. Arsenic is supposed to be adsorbed in the form of triangles As 3 and tetrahedrons As 4, each of them occupying 3 atomic sites above In or As atoms on (111)In or (111)As, respectively. The system of polyatomic adsorption equations was used to find the coverages of the faces by various species. Admolecule-surface bond strengths are taken to be equal to the ones for the single bonds in molecules. Pauling electronegativities were used to find the effective charges of the atoms in the adsorption layer. Thus, the dipole moments of adsorbed molecules which arise are directed along the In-As bonds in the InAs lattice. With this geometry, the calculated electrostatic dipole-dipole attraction between InCl molecules forming a dense layer on (111)As exceeds 12 kcal/mol. Thus, condensation of the two-dimensional gas of adsorbed InCl molecules should be expected. Corresponding S-shape isotherms θ( P) are calculated for different As 3 vapor pressures, θ and P being the surface coverage and bulk vapor pressure of InCl. Intervals of {InCl 3}/{H 2} ratios at different temperatures where the two-dimensional condensation may occur, are presented for realistic CVD conditions. Two-dimensional condensation may result in sharp changes in kinetic coefficient and thus in autho-oscillations in growth rate and doping level creating periodic superstructures. Nucleation and CVD growth processes are discussed.

  3. Kinetics of the homogeneous exchange of alpha-lactalbumin adsorbed on titanium oxide surface.

    Science.gov (United States)

    Bentaleb, A; Haïkel, Y; Voegel, J C; Schaaf, P

    1998-06-05

    The homogeneous exchange process whereby alpha-lactalbumine molecules adsorbed on hydrophilic titanium oxide particles are replaced by alpha-lactalbumine molecules in solution has been investigated by means of a 125I radio-labeling technique, alpha-lactalbumine is a compact and highly negatively charged protein, making this study complementary to previous work devoted to the general understanding of the exchange mechanisms of adsorbed proteins on solid surfaces. The isotherm of alpha-lactalbumine exhibits bimodal adsorption shape, and the exchange process whereby adsorbed proteins are replaced by new incoming ones from the bulk solution has been studied at both the upper and the lower plateau of the isotherm. In the upper plateau the exchange process was found to be of first order with respect to the bulk molecules, and the release rate constant was equal to 0.914 L. mol-1.s-1. This behavior is identical to what has been observed with other proteinic systems. In the lower plateau domain, in contrast, the protein release process is independent of the concentration of proteins in the bulk, but the release rates are higher than the pure desorption rates. This constitutes, to our knowledge, a behavior that never before has been observed and that remains to be explained.

  4. Photoemission spectroscopy of surfaces and adsorbates

    International Nuclear Information System (INIS)

    Chiang, T.C.; Kaindl, G.; Himpsel, F.J.; Eastman, D.E.

    1982-01-01

    Core level photoelectron spectroscopy is providing new information concerning the electronic properties of adsorbates and surfaces. Several examples will be discussed, including studies of adsorbed rare gas submonolayers and multilayers as well as clean metal surfaces. For rare gas multilayers adsorbed on metal surfaces, the photoelectrons and Auger electrons exhibit well-resolved increases in kinetic energy with decreasing distance between the excited atom and the substrate, allowing a direct labeling of the layers. These energy shifts are mainly due to the substrate screening effects, and can be described well by an image-charge model. For a Kr/Xe bilayer system prepared by first coating a Pd substrate with a monolayer of Kr and then overcoating with a layer of Xe, a thermally activated layer inversion process is observed when the temperature is raised, with Xe coming in direct contact with the substrate. For rare gas submonolayers adsorbed on the Al(111) surface, coverage-dependent core level shift and work function measurements provide information about the adatom spatial distributions, polarizabilities, and dipole moments for the ground and excited states. We have also studied the 2p core level shifts for a clean Al(001) surface relative to the bulk. The shifts have a large contribution from the initial-state effects

  5. Heterogeneous membranes filled with hypercrosslinked microparticle adsorbent

    Czech Academy of Sciences Publication Activity Database

    Hradil, Jiří; Krystl, V.; Hrabánek, P.; Bernauer, B.; Kočiřík, Milan

    2005-01-01

    Roč. 65, 1-2 (2005), s. 57-68 ISSN 1381-5148 R&D Projects: GA ČR GA104/03/0680 Institutional research plan: CEZ:AV0Z40500505 Keywords : heterogeneous membranes * hypercrosslinked adsorbent * microparticle s Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.565, year: 2005

  6. Structural and electronic properties of the adsorbed and defected Cu nanowires: A density-functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Ying-Ni [College of Physics and Information Technology, Shaanxi Normal University, Xian 710062, Shaanxi (China); Department of Medical Engineering and Technology, Xinjiang Medical University, Urumqi 830011, Xinjiang (China); Zhang, Jian-Min, E-mail: jianm_zhang@yahoo.com [College of Physics and Information Technology, Shaanxi Normal University, Xian 710062, Shaanxi (China); Fan, Xiao-Xi [Department of Medical Engineering and Technology, Xinjiang Medical University, Urumqi 830011, Xinjiang (China); Xu, Ke-Wei [College of Physics and Mechanical and Electronic Engineering, Xian University of Arts and Science, Xian 710065, Shaanxi (China)

    2014-12-01

    Using first-principles calculations based on density-functional theory, we systematically investigate the influence of adsorbates (CO molecule and O atom) and defects (adsorb one extra Cu atom and monovacancy) on the structural and electronic properties of Cu{sub 5-1}NW and Cu{sub 6-1}NW. For both nanowires, CO molecule prefers to adsorb on the top site, while O atom prefers to adsorb on the center site. The hybridization between the CO and Cu states is dominated by the donation–backdonation process, which leads to the formation of bonding/antibonding pairs, 5σ{sub b}/5σ{sub a} and 2π{sub b}{sup ⁎}/2π{sub a}{sup ⁎}. The larger adsorption energies, larger charge transfers to O adatom and larger decrease in quantum conductance 3G{sub 0} for an O atom adsorbed on the Cu{sub 5-1}NW and Cu{sub 6-1}NW show both Cu{sub 5-1}NW and Cu{sub 6-1}NW can be used as an O sensor. Furthermore, the decrease in quantum conductance 1G{sub 0} for a CO molecule adsorbed on the Cu{sub 6-1}NW also shows the Cu{sub 6-1}NW can be used to detect CO molecule. So we expect these results may have implications for CuNW based chemical sensing. High adsorption energy of one extra Cu atom and relatively low formation energy of a monovacancy suggest that these two types of defects are likely to occur in the fabrication of CuNWs. One extra Cu atom does not decrease the quantum conductance, while a Cu monovacancy leads to a drop of the quantum conductance.

  7. Constructing a proton titration curve from ion-step measurements, applied to a membrane with adsorbed protein

    NARCIS (Netherlands)

    Eijkel, Jan C.T.; Bosch, Coen; Olthuis, Wouter; Bergveld, Piet

    1997-01-01

    A new measuring method is described for obtaining a proton titration curve. The curve is obtained from a microporous composite membrane, consisting of polystyrene beads in an agarose matrix, with lysozyme molecules adsorbed to the bead surface. The membrane is incorporated into a sensor system by

  8. Mechanochemical synthesis of small organic molecules

    Directory of Open Access Journals (Sweden)

    Tapas Kumar Achar

    2017-09-01

    Full Text Available With the growing interest in renewable energy and global warming, it is important to minimize the usage of hazardous chemicals in both academic and industrial research, elimination of waste, and possibly recycle them to obtain better results in greener fashion. The studies under the area of mechanochemistry which cover the grinding chemistry to ball milling, sonication, etc. are certainly of interest to the researchers working on the development of green methodologies. In this review, a collection of examples on recent developments in organic bond formation reactions like carbon–carbon (C–C, carbon–nitrogen (C–N, carbon–oxygen (C–O, carbon–halogen (C–X, etc. is documented. Mechanochemical syntheses of heterocyclic rings, multicomponent reactions and organometallic molecules including their catalytic applications are also highlighted.

  9. Biological regeneration of carrier material for the adsorption of halogen hydrocarbons in plants for cleaning up contaminated groundwater. Final report

    International Nuclear Information System (INIS)

    Ressel, K.

    1993-06-01

    Halogen hydrocarbons and above all chlorinated hydrocarbons are widespread harmful substances in soils and in groundwater. When cleaning up groundwater contamination, the contaminants are brought into the gas phase by strip processes. From the gas phase, the contaminants can be adsorbed on different carrier materials, mostly active carbon. One was searching for ways to regenerate this adsorption material. The mixed culture from a sea sediment most suitable for the decomposition of chlorinated hydrocarbons was optimized regarding its decomposition performance and was later used on the technical scale. In the decomposition experiments on the large technical scale, the cultures were lodged on filling bodies which has a much higher amount of gaps. In this case, an optimum supply of the micro-organisms with oxygen and methane is guaranteed, which is used as co-substrate. No intermediate product was found in a gas chromatography examination. The biologically occupied stage is situated between a desorption column and the active carbon filters, and reduces the load of harmful substances which can no longer be brought into the gas phase by stripping out. This has the advantage that it can be integrated in existing plants and can be adapted to any case of contamination by lodging adapted micro-organisms on it. The basis for each application must be separately researched. (orig.) [de

  10. 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.

  11. Oxidation of monovacancies in graphene by oxygen molecules

    KAUST Repository

    Kaloni, Thaneshwor P.

    2011-10-14

    We study the oxidation of monovacancies in graphene by oxygen molecules using first principles calculations. In particular, we address the local magnetic moments which develop at monovacancies and show that they remain intact when a molecule is adsorbed such that the dangling carbon bonds are not fully saturated. However, the lowest energy configuration does not maintain dangling bonds and is found to be semiconducting. Our data can explain the experimentally observed behavior of graphene under exposure to an oxygen plasma.

  12. Oxidation of monovacancies in graphene by oxygen molecules

    KAUST Repository

    Kaloni, Thaneshwor P.; Cheng, Yingchun; Faccio, R.; Schwingenschlö gl, Udo

    2011-01-01

    We study the oxidation of monovacancies in graphene by oxygen molecules using first principles calculations. In particular, we address the local magnetic moments which develop at monovacancies and show that they remain intact when a molecule is adsorbed such that the dangling carbon bonds are not fully saturated. However, the lowest energy configuration does not maintain dangling bonds and is found to be semiconducting. Our data can explain the experimentally observed behavior of graphene under exposure to an oxygen plasma.

  13. The adsorber loop concept for the contact between seawater and adsorber granulate

    International Nuclear Information System (INIS)

    Koske, P.H.; Ohlrogge, K.

    1984-01-01

    The present paper deals with the so-called ''adsorber loop concept'' in which the adsorber granulate is carried along with the seawater to be processed in a loop-like configuration and is separated again from the depleted water before this is leaving the adsorption unit. This concept enables high seawater velocities thus reducing the required bed area. Theoretical considerations are presented together with experimental results from field tests. (orig.) [de

  14. Molecules and Models The molecular structures of main group element compounds

    CERN Document Server

    Haaland, Arne

    2008-01-01

    This book provides a systematic description of the molecular structures and bonding in simple compounds of the main group elements with particular emphasis on bond distances, bond energies and coordination geometries. The description includes the structures of hydrogen, halogen and methyl derivatives of the elements in each group, some of these molecules are ionic, some polar covalent. The survey of molecules whose structures conform to well-established trends is followed byrepresentative examples of molecules that do not conform. We also describe electron donor-acceptor and hydrogen bonded co

  15. Possible pore size effects on the state of tris(8-quinolinato)aluminum(III) (Alq3) adsorbed in mesoporous silicas and their temperature dependence.

    Science.gov (United States)

    Tagaya, Motohiro; Ogawa, Makoto

    2008-12-07

    The states of tris(8-quinolinato)aluminum(III) (Alq3) adsorbed in mesoporous silicas with different pore sizes (2.5, 3.1 and 5.0 nm) were investigated. Alq3 was successfully occluded into the mesoporous silicas from solution and the adsorbed amount of Alq3 per BET surface area was effectively controlled by changing the added amount Alq3 to the solution. The state of Alq3 in the mesopore varied depending on the pore size as well as the adsorbed amount of Alq3 as revealed by variation of the photoluminescence spectra. The luminescence of the adsorbed Alq3 was found to be temperature-dependent, indicating the mobility of the adsorbed Alq3 to temperature variations. The temperature-dependence also depended on the pore size. The guest-guest interactions between Alq3 molecules as well as the host-guest interactions between Alq3 and the mesopore were controlled by the pore size.

  16. Electronic spectral properties of surfaces and adsorbates and atom-adsorbate van der Waals interactions

    International Nuclear Information System (INIS)

    Lovric, D.; Gumhalter, B.

    1988-01-01

    The relevance of van der Waals interactions in the scattering of neutral atoms from adsorbates has been recently confirmed by highly sensitive molecular-beam techniques. The theoretical descriptions of the collision dynamics which followed the experimental studies have necessitated very careful qualitative and quantitative examinations and evaluations of the properties of atom-adsorbate van der Waals interactions for specific systems. In this work we present a microscopic calculation of the strengths and reference-plane positions for van der Waals potentials relevant for scattering of He atoms from CO adsorbed on various metallic substrates. In order to take into account the specificities of the polarization properties of real metals (noble and transition metals) and of chemisorbed CO, we first calculate the spectra of the electronic excitations characteristic of the respective electronic subsystems by using various data sources available and combine them with the existing theoretical models. The reliability of the calculated spectra is then verified in each particular case by universal sum rules which may be established for the electronic excitations of surfaces and adsorbates. The substrate and adsorbate polarization properties which derive from these calculations serve as input data for the evaluation of the strengths and reference-plane positions of van der Waals potentials whose computed values are tabulated for a number of real chemisorption systems. The implications of the obtained results are discussed in regard to the atom-adsorbate scattering cross sections pertinent to molecular-beam scattering experiments

  17. Characterization of Adsorbents for Cytokine Removal from Blood in an In Vitro Model.

    Science.gov (United States)

    Harm, Stephan; Gabor, Franz; Hartmann, Jens

    2015-01-01

    Cytokines are basic targets that have to be removed effectively in order to improve the patient's health status in treating severe inflammation, sepsis, and septic shock. Although there are different adsorbents commercially available, the success of their clinical use is limited. Here, we tested different adsorbents for their effective removal of cytokines from plasma and the resulting effect on endothelial cell activation. The three polystyrene divinylbenzene (PS-DVB) based adsorbents Amberchrom CG161c and CG300m and a clinically approved haemoperfusion adsorbent (HAC) were studied with regard to cytokine removal in human blood. To induce cytokine release from leucocytes, human blood cells were stimulated with 1 ng/ml LPS for 4 hours. Plasma was separated and adsorption experiments in a dynamic model were performed. The effect of cytokine removal on endothelial cell activation was evaluated using a HUVEC-based cell culture model. The beneficial outcome was assessed by measuring ICAM-1, E-selectin, and secreted cytokines IL-8 and IL-6. Additionally the threshold concentration for HUVEC activation by TNF-α and IL-1β was determined using this cell culture model. CG161c showed promising results in removing the investigated cytokines. Due to its pore size the adsorbent efficiently removed the key factor TNF-α, outperforming the commercially available adsorbents. The CG161c treatment reduced cytokine secretion and expression of cell adhesion molecules by HUVEC which underlines the importance of effective removal of TNF-α in inflammatory diseases. These results confirm the hypothesis that cytokine removal from the blood should approach physiological levels in order to reduce endothelial cell activation.

  18. Sulfur removal from fuel using zeolites/polyimide mixed matrix membrane adsorbents

    International Nuclear Information System (INIS)

    Lin, Ligang; Wang, Andong; Dong, Meimei; Zhang, Yuzhong; He, Benqiao; Li, Hong

    2012-01-01

    Graphical abstract: Membrane adsorption process is proposed for sulfur removal. Three-dimensional network structure is key to fulfill adsorption function of MMMs, which adsorption/desorption behavior is markedly related with binding force with sulfur molecules. Highlights: ► Membrane adsorption process is proposed for sulfur removal. ► Three-dimensional network structure of MMMs is key to fulfill adsorption function. ► Adsorption/desorption behavior is markedly related with binding force. - Abstract: A novel membrane adsorption process was proposed for the sulfur removal from fuels. The mixed matrix membranes (MMMs) adsorbents composed of polyimide (PI) and various Y zeolites were prepared. By the detailed characterization of FT-IR, morphology, thermal and mechanical properties of MMMs adsorbents, combining the adsorption and desorption behavior research, the process–structure–function relationship was discussed. Field-emission scanning electron microscope (FESEM) images show that the functional particles are incorporated into the three-dimensional network structure. MMMs adsorbents with 40% of zeolites content possess better physical properties, which was confirmed by mechanical strength and thermo stability analysis. Influence factors including post-treatment, content of incorporated zeolites, adsorption time, temperature, initial sulfur concentration as well as sulfur species on the adsorption performance of MMMs adsorbents have been evaluated. At 4 wt.% zeolites content, adsorption capacity for NaY/PI, AgY/PI and CeY/PI MMMs adsorbents come to 2.0, 7.5 and 7.9 mg S/g, respectively. And the regeneration results suggest that the corresponding spent membranes can recover about 98%, 90% and 70% of the desulfurization capacity, respectively. The distinct adsorption and desorption behavior of MMMs adsorbents with various functional zeolites was markedly related with their various binding force and binding mode with sulfur compounds.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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....

  4. 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.

  5. 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....

  6. 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.

  7. Observing single molecule chemical reactions on metal nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    Emory, S. R. (Steven R.); Ambrose, W. Patrick; Goodwin, P. M. (Peter M); Keller, Richard A.

    2001-01-01

    We report the study of the photodecomposition of single Rhodamine 6G (R6G) dye molecules adsorbed on silver nanoparticles. The nanoparticles were immobilized and spatially isolated on polylysine-derivatized glass coverslips, and confocal laser microspectroscopy was used to obtain surface-enhanced Raman scattering (SERS) spectra from individual R6G molecules. The photodecomposition of these molecules was observed with 150-ms temporal resolution. The photoproduct was identified as graphitic carbon based on the appearance of broad SERS vibrational bands at 1592 cm{sup -1} and 1340 cm{sup -1} observed in both bulk and averaged single-molecule photoproduct spectra. In contrast, when observed at the single-molecule level, the photoproduct yielded sharp SERS spectra. The inhomogeneous broadening of the bulk SERS spectra is due to a variety of photoproducts in different surface orientations and is a characteristic of ensemble-averaged measurements of disordered systems. These single-molecule studies indicate a photodecomposition pathway by which the R6G molecule desorbs from the metal surface, an excited-state photoreaction occurs, and the R6G photoproduct(s) readsorbs to the surface. A SERS spectrum is obtained when either the intact R6G or the R6G photoproduct(s) are adsorbed on a SERS-active site. This work further illustrates the power of single-molecule spectroscopy (SMS) to reveal unique behaviors of single molecules that are not discernable with bulk measurements.

  8. 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.

  9. Adsorbents for radioactive organic solvent wastes

    International Nuclear Information System (INIS)

    Ichinose, Shigeo; Kiribayashi, Takehiko.

    1986-01-01

    Purpose: To enable to settle radioactive solvents such as tributyl phosphate (TBP) and n-dodecane as they are without using hydrophobicizing agent such as quaternary ammonium salts. Constitution: The adsorbents are prepared by replacing interlaminer ions of swelling-type synthetic mica with alkaline earth metals or metal ions. For instance, synthetic micas introduced with Zr 4+ or Ca 2+ between the layers provide quite different functions from those of starting materials due to the properties of ions introduced between the layers. That is, they provide an intense affinity to organic phosphates such as TBP and transform into material showing a property of adsorbing and absorbing them. Particularly, the fixing nature to the phosphor content constituting TBP is significantly increased. (Horiuchi, T.)

  10. Analysis of Adsorbed Natural Gas Tank Technology

    Science.gov (United States)

    Knight, Ernest; Schultz, Conrad; Rash, Tyler; Dohnke, Elmar; Stalla, David; Gillespie, Andrew; Sweany, Mark; Seydel, Florian; Pfeifer, Peter

    With gasoline being an ever decreasing finite resource and with the desire to reduce humanity's carbon footprint, there has been an increasing focus on innovation of alternative fuel sources. Natural gas burns cleaner, is more abundant, and conforms to modern engines. However, storing compressed natural gas (CNG) requires large, heavy gas cylinders, which limits space and fuel efficiency. Adsorbed natural gas (ANG) technology allows for much greater fuel storage capacity and the ability to store the gas at a much lower pressure. Thus, ANG tanks are much more flexible in terms of their size, shape, and weight. Our ANG tank employs monolithic nanoporous activated carbon as its adsorbent material. Several different configurations of this Flat Panel Tank Assembly (FPTA) along with a Fuel Extraction System (FES) were examined to compare with the mass flow rate demands of an engine.

  11. Adsorption of aromatic compounds by carbonaceous adsorbents: a comparative study on granular activated carbon, activated carbon fiber, and carbon nanotubes.

    Science.gov (United States)

    Zhang, Shujuan; Shao, Ting; Kose, H Selcen; Karanfil, Tanju

    2010-08-15

    Adsorption of three aromatic organic compounds (AOCs) by four types of carbonaceous adsorbents [a granular activated carbon (HD4000), an activated carbon fiber (ACF10), two single-walled carbon nanotubes (SWNT, SWNT-HT), and a multiwalled carbon nanotube (MWNT)] with different structural characteristics but similar surface polarities was examined in aqueous solutions. Isotherm results demonstrated the importance of molecular sieving and micropore effects in the adsorption of AOCs by carbonaceous porous adsorbents. In the absence of the molecular sieving effect, a linear relationship was found between the adsorption capacities of AOCs and the surface areas of adsorbents, independent of the type of adsorbent. On the other hand, the pore volume occupancies of the adsorbents followed the order of ACF10 > HD4000 > SWNT > MWNT, indicating that the availability of adsorption site was related to the pore size distributions of the adsorbents. ACF10 and HD4000 with higher microporous volumes exhibited higher adsorption affinities to low molecular weight AOCs than SWNT and MWNT with higher mesopore and macropore volumes. Due to their larger pore sizes, SWNTs and MWNTs are expected to be more efficient in adsorption of large size molecules. Removal of surface oxygen-containing functional groups from the SWNT enhanced adsorption of AOCs.

  12. Ballistic thermophoresis of adsorbates on free-standing graphene.

    Science.gov (United States)

    Panizon, Emanuele; Guerra, Roberto; Tosatti, Erio

    2017-08-22

    The textbook thermophoretic force which acts on a body in a fluid is proportional to the local temperature gradient. The same is expected to hold for the macroscopic drift behavior of a diffusive cluster or molecule physisorbed on a solid surface. The question we explore here is whether that is still valid on a 2D membrane such as graphene at short sheet length. By means of a nonequilibrium molecular dynamics study of a test system-a gold nanocluster adsorbed on free-standing graphene clamped between two temperatures [Formula: see text] apart-we find a phoretic force which for submicron sheet lengths is parallel to, but basically independent of, the local gradient magnitude. This identifies a thermophoretic regime that is ballistic rather than diffusive, persisting up to and beyond a 100-nanometer sheet length. Analysis shows that the phoretic force is due to the flexural phonons, whose flow is known to be ballistic and distance-independent up to relatively long mean-free paths. However, ordinary harmonic phonons should only carry crystal momentum and, while impinging on the cluster, should not be able to impress real momentum. We show that graphene and other membrane-like monolayers support a specific anharmonic connection between the flexural corrugation and longitudinal phonons whose fast escape leaves behind a 2D-projected mass density increase endowing the flexural phonons, as they move with their group velocity, with real momentum, part of which is transmitted to the adsorbate through scattering. The resulting distance-independent ballistic thermophoretic force is not unlikely to possess practical applications.

  13. Band mapping of surface states vs. adsorbate coverage

    International Nuclear Information System (INIS)

    Rotenberg, E.; Kevan, S.D.; Denlinger, J.D.; Chung, Jin-Wook

    1997-01-01

    The theory of electron bands, which arises from basic quantum mechanical principles, has been the cornerstone of solid state physics for over 60 years. Simply put, an energy band is an electron state in a solid whose energy varies with its momentum (similar to, but with a more complicated dependence than, how a free electron's energy is proportional to its momentum squared). Much attention over the last 15 years has been given to the study of band structure of surfaces and interfaces, especially as the applications of these two-dimensional systems have become increasingly important to industry and science. The ultraESCA endstation at beamline 7.01 at the Advanced Light Source was developed for very high-energy - (∼50 meV) and angular - ( 12 photons/sec) makes the detailed study of the evolution of bands possible. The authors are interested in learning how, when one forms a chemical bond between a metal and an overlaying atom or molecule, the resulting charge transfer to or from the adsorbate affects the surface bands. In some cases of interest, intermediate coverages lead to different band structure than at the extremes of clean and saturated surfaces. Surfaces of tungsten are particularly interesting, as their atomic geometry has been shown to be exquisitely sensitive to both the surface vibrational and electronic properties. In this study, the authors looked at the surface bands of tungsten ((110) surface), as a function both of coverage and mass of overlaying atoms. The adsorbed atoms were hydrogen and the alkali atoms lithium and cesium

  14. Green Adsorbents for Wastewaters: A Critical Review

    Directory of Open Access Journals (Sweden)

    George Z. Kyzas

    2014-01-01

    Full Text Available One of the most serious environmental problems is the existence of hazardous and toxic pollutants in industrial wastewaters. The major hindrance is the simultaneous existence of many/different types of pollutants as (i dyes; (ii heavy metals; (iii phenols; (iv pesticides and (v pharmaceuticals. Adsorption is considered to be one of the most promising techniques for wastewater treatment over the last decades. The economic crisis of the 2000s led researchers to turn their interest in adsorbent materials with lower cost. In this review article, a new term will be introduced, which is called “green adsorption”. Under this term, it is meant the low-cost materials originated from: (i agricultural sources and by-products (fruits, vegetables, foods; (ii agricultural residues and wastes; (iii low-cost sources from which most complex adsorbents will be produced (i.e., activated carbons after pyrolysis of agricultural sources. These “green adsorbents” are expected to be inferior (regarding their adsorption capacity to the super-adsorbents of previous literature (complex materials as modified chitosans, activated carbons, structurally-complex inorganic composite materials etc., but their cost-potential makes them competitive. This review is a critical approach to green adsorption, discussing many different (maybe in some occasions doubtful topics such as: (i adsorption capacity; (ii kinetic modeling (given the ultimate target to scale up the batch experimental data to fixed-bed column calculations for designing/optimizing commercial processes and (iii critical techno-economical data of green adsorption processes in order to scale-up experiments (from lab to industry with economic analysis and perspectives of the use of green adsorbents.

  15. Generating Atomistic Slab Surfaces with Adsorbates

    Science.gov (United States)

    2017-12-01

    slabs of various thickness and with various vacuum spacing need be calculated. This can occur in serial or simultaneously . If performed in serial, the...the user. Although the optimization of the slab thickness and vacuum padding can be done simultaneously , it is more computationally conservative to...monolayer is a slab (True if slab), the type of mesh desired (adsorbates.py was written for “Gamma”), how detailed the mesh should be (in units of inverse

  16. Green Adsorbents for Wastewaters: A Critical Review

    Science.gov (United States)

    Kyzas, George Z.; Kostoglou, Margaritis

    2014-01-01

    One of the most serious environmental problems is the existence of hazardous and toxic pollutants in industrial wastewaters. The major hindrance is the simultaneous existence of many/different types of pollutants as (i) dyes; (ii) heavy metals; (iii) phenols; (iv) pesticides and (v) pharmaceuticals. Adsorption is considered to be one of the most promising techniques for wastewater treatment over the last decades. The economic crisis of the 2000s led researchers to turn their interest in adsorbent materials with lower cost. In this review article, a new term will be introduced, which is called “green adsorption”. Under this term, it is meant the low-cost materials originated from: (i) agricultural sources and by-products (fruits, vegetables, foods); (ii) agricultural residues and wastes; (iii) low-cost sources from which most complex adsorbents will be produced (i.e., activated carbons after pyrolysis of agricultural sources). These “green adsorbents” are expected to be inferior (regarding their adsorption capacity) to the super-adsorbents of previous literature (complex materials as modified chitosans, activated carbons, structurally-complex inorganic composite materials etc.), but their cost-potential makes them competitive. This review is a critical approach to green adsorption, discussing many different (maybe in some occasions doubtful) topics such as: (i) adsorption capacity; (ii) kinetic modeling (given the ultimate target to scale up the batch experimental data to fixed-bed column calculations for designing/optimizing commercial processes) and (iii) critical techno-economical data of green adsorption processes in order to scale-up experiments (from lab to industry) with economic analysis and perspectives of the use of green adsorbents. PMID:28788460

  17. Adsorbate Diffusion on Transition Metal Nanoparticles

    Science.gov (United States)

    2015-01-01

    correlation is a Bronsted-Evans-Polanyi ( BEP )- type of correlation, similar to other BEP correlations established earlier for surface-catalyzed bond- breaking...bond-making reactions.6-9 The universal BEP -type correlation is independent of the nature of the adsorbed species and that of the metal surface. For...a certain class of surface-catalyzed reactions, the existence of a BEP -type correlation reflects a similarity between the geometry of the transition

  18. Theoretical Insight of Physical Adsorption for a Single-Component Adsorbent + Adsorbate System: I. Thermodynamic Property Surfaces

    KAUST Repository

    Chakraborty, Anutosh; Saha, Bidyut Baran; Ng, Kim Choon; Koyama, Shigeru; Srinivasan, Kandadai

    2009-01-01

    Thermodynamic property surfaces for a single-component adsorbent + adsorbate system are derived and developed from the viewpoint of classical thermodynamics, thermodynamic requirements of chemical equilibrium, Gibbs law, and Maxwell relations

  19. Biological adsorbent for water decontamination from uranium

    Energy Technology Data Exchange (ETDEWEB)

    Jilek, R [Vyzkumny Ustav Veterinarniho Lekarstvi, Brno-Medlanky (Czechoslovakia); Fuska, J; Nemec, P [Slovenska Vysoka Skola Technicka, Bratislava (Czechoslovakia). Chemickotechnologicka Fakulta

    1978-01-01

    A study was made into the capacity of native and heat-denaturated mycelium to adsorb uranium salts from solutions and into the effect of uranium on the growth of the microorganism biomass. The presence of uranium did not inhibit the growth of Penicillium and Aspergillus strains used at a concentration of up to 5x10/sup -4/ M/dm/sup 3/. Uranium added to a nutrient medium produced complexes with phosphorus ions which were adsorbed on the surface of growing hyphae, thus the removal of the mycelium also removed uranium. The results of the experiments with denaturated mycelium of the same strains suggested that uranium was also bound to the biomass with chemical bonds so that mycelium acted as a ''multifunction ion exchanger'' from which adsorbed uranium can be removed step by step by elution. A sorbent of a three-dimensional structure could be prepared from a dried native mycelium using reinforcing resins, which prevented leakage of the biomass. Uranium sorption by biosorbents is a function of the concentration of the cation sorbed and of the pH of the solution.

  20. Biological adsorbent for water decontamination from uranium

    International Nuclear Information System (INIS)

    Jilek, R.; Fuska, J.; Nemec, P.

    1978-01-01

    A study was made into the capacity of native and heat-denaturated mycelium to adsorb uranium salts from solutions and into the effect of uranium on the growth of the microorganism biomass. The presence of uranium did not inhibit the growth of Penicillium and Aspergillus strains used at a concentration of up to 5x10 -4 M/dm 3 . Uranium added to a nutrient medium produced complexes with phosphorus ions which were adsorbed on the surface of growing hyphae, thus the removal of the mycelium also removed uranium. The results of the experiments with denaturated mycelium of the same strains suggested that uranium was also bound to the biomass with chemical bonds so that mycelium acted as a ''multifunction ion exchanger'' from which adsorbed uranium can be removed step by step by elution. A sorbent of a three-dimensional structure could be prepared from a dried native mycelium using reinforcing resins, which prevented leakage of the biomass. Uranium sorption by biosorbents is a function of the concentration of the cation sorbed and of the pH of the solution. (author)

  1. Optimization of the elaboration conditions of an adsorber for the hydrogen storage; Optimisation des conditions d'elaboration d'un adsorbant pour le stockage d'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Fierro, V.; Mareche, J.F.; Furdin, G. [Nancy-1 Univ. Henri Poincare, UMR - CNRS 7555, Laboratoire de Chimie du Solide Mineral, 54 - Vandoeuvre-les-Nancy (France); Szczurek, A.; Albiniak, A. [Wroclaw Univ. of Technology, Laboratory for Lignites and Carbon Adsorbents, Institute of Chemistry and Technology of Petroleum and Coal (Poland); Latroche, M. [Chimie Metallurgique des Terres Rares, ICMPE, UMR 7182, CNRS, 94 - Thiais (France); Celzard, A. [Nancy-Univ., ENSTIB, Laboratoire de Chimie du Solide Mineral, UMR CNRS 7555, 88 - Epinal (France)

    2008-07-01

    The microporous carbon are very efficient adsorbents for the hydrogen storage, because of pores size under 2 nm. This study describes the optimization of the elaboration conditions for a carbon adsorbent for the hydrogen storage by adsorption. The storage capacity has been measured at 25 C for 20 MPa and also at 77 K for pressures between 6 and 9 MPa. the porous texture characterization has been realized by four molecule probes of increasing diameter: CO{sub 2}, N{sub 2}, C{sub 6}H{sub 6} and CCl{sub 4}. (A.L.B.)

  2. Toluene and acetaldehyde removal from air on to graphene-based adsorbents with microsized pores.

    Science.gov (United States)

    Kim, Ji Min; Kim, Ji Hoon; Lee, Chang Yeon; Jerng, Dong Wook; Ahn, Ho Seon

    2018-02-15

    Volatile organic compound (VOC) gases can cause harm to the human body with exposure over the long term even at very low concentrations (ppmv levels); thus, effective absorbents for VOC gas removal are an important issue. In this study, accordingly, graphene-based adsorbents with microsized pores were used as adsorbents to remove toluene and acetaldehyde gases at low concentrations (30ppm). Sufficient amounts of the adsorbents were prepared for use on filters and were loaded uniformly at 0.1-0.5g on a 50×50mm 2 area, to evaluate their adsorption features with low gas concentrations. The morphology and chemical composition of the adsorbents were characterized using scanning electron microscopy, N 2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and Raman spectroscopy. Microwave irradiation and heat treatment near 800°C under KOH activation resulted in enlargement of the pristine graphene surface and its specific surface area; maximum volume capacities of 3510m 3 /g and 630m 3 /g were observed for toluene and acetaldehyde gas. The high removal efficiency for toluene (98%) versus acetaldehyde (30%) gas was attributed to π-π interactions between the pristine graphene surface and toluene molecules. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. 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

  4. 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.

  5. 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...

  6. 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.

  7. 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)

  8. Electron and photon-beam induced reactions of adsorbed disilane: Low-temperature thin-film growth

    International Nuclear Information System (INIS)

    Bozso, F.; Avouris, Ph.

    1991-01-01

    Electrons and photons of sufficient energy can cause fragmentation and desorption of adsorbed molecules or fragments of them, by inducing electronic excitations to dissociative states. The surface species after such excitations are mostly of highly reactive radical character, which readily react with the substrate and with other molecular or radical species in the adsorbed layer. This paper discusses the adsorption, thermal and electron/photon-beam induced reactions of disilane, oxygen and ammonia on Si(111)-7x7, and the electron/photon-induced growth of silicon, silicon dioxide and silicon nitride films at 100K

  9. Study of composite adsorbent synthesis and characterization for the removal of Cs in the high-salt and high-radioactive wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jimin; Lee, Keun Young; Kim, Kwang Wook; Lee, Eil Hee; Chung, Dong Yong; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Hyun, Jae Hyuk [Chungnam National University, Daejeon (Korea, Republic of)

    2017-03-15

    For the removal of cesium (Cs) from high radioactive/high salt-laden liquid waste, this study synthesized a highly efficient composite adsorbent (potassium cobalt ferrocyanide (PCFC)-loaded chabazite (CHA)) and evaluated its applicability. The composite adsorbent used CHA, which could accommodate Cs as well as other molecules, as a supporting material and was synthesized by immobilizing the PCFC in the pores of CHA through stepwise impregnation/precipitation with CoCl{sub 2} and K{sub 4}Fe (CN){sub 6} solutions. When CHA, with average particle size of more than 10 μm, is used in synthesizing the composite adsorbent, the PCFC particles were immobilized in a stable form. Also, the physical stability of the composite adsorbent was improved by optimizing the washing methodology to increase the purity of the composite adsorbent during the synthesis. The composite adsorbent obtained from the optimal synthesis showed a high adsorption rate of Cs in both fresh water (salt-free condition) and seawater (high-salt condition), and had a relatively high value of distribution coefficient (larger than 10{sup 4} mL·g{sup -1}) regardless of the salt concentration. Therefore, the composite adsorbent synthesized in this study is an optimized material considering both the high selectivity of PCFC on Cs and the physical stability of CHA. It is proved that this composite adsorbent can remove rapidly Cs contained in high radioactive/high salt-laden liquid waste with high efficiency.

  10. 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.

  11. The adsorber loop concept for the contact between seawater and adsorber granulate

    International Nuclear Information System (INIS)

    Koske, P.H.; Ohlrogge, K.

    1984-01-01

    For the production of 1 kg uranium from seawater about 10 9 kg seawater - depending on the extraction efficiency - have to be processed in a production plant. Such high seawater flows have to be put through adsorber beds the area of which depends on the flow velocity of the water in the bed. For a typical polyamidoxim (PAO) adsorber granulate with a grain size distribution of 0.3 to 1.2 mm the velocity in a fluidized bed is limited to about 1 cm/s in order to prevent carry out of the adsorber material. The consequences of this rather low bed velocity are large and expensive bed areas for technical production plants. The present paper deals with the so-called ''adsorber loop concept'' in which the adsorber granulate is carried along with the seawater to be processed in a loop-like configuration and is separated again from the water before this is leaving the adsorption unit. This concept enables considerably higher seawater velocities thus reducing the bed area. Theoretical considerations are presented together with experimental results from field tests. (author)

  12. Surface enhanced Raman scattering of new acridine based fluorophore adsorbed on silver electrode

    Science.gov (United States)

    Solovyeva, Elena V.; Myund, Liubov A.; Denisova, Anna S.

    2015-10-01

    4,5-Bis(N,N-di(2-hydroxyethyl)iminomethyl)acridine (BHIA) is a new acridine based fluoroionophore and a highly-selective sensor for cadmium ion. The direct interaction of the aromatic nitrogen atom with a surface is impossible since there are bulky substituents in the 4,5-positions of the acridine fragment. Nevertheless BHIA molecule shows a reliable SERS spectrum while adsorbed on a silver electrode. The analysis of SERS spectra pH dependence reveals that BHIA species adsorbed on a surface can exist in both non-protonated and protonated forms. The adsorption of BHIA from alkaline solution is accompanied by carbonaceous species formation at the surface. The intensity of such "carbon bands" turned out to be related with the supporting electrolyte (KCl) concentration. Upon lowering the electrode potential the SERS spectra of BHIA do not undergo changes but the intensity of bands decreases. This indicates that the adsorption mechanism on the silver surface is realized via aromatic system of acridine fragment. In case of such an adsorption mechanism the chelate fragment of the BHIA molecule is capable of interaction with the solution components. Addition of Cd2+ ions to a system containing BHIA adsorbed on a silver electrode in equilibrium with the solution leads to the formation of BHIA/Cd2+ complex which desorption causes the loss of SERS signal.

  13. Hindered rotation of a copper phthalocyanine molecule on C60 : Experiments and molecular mechanics calculations

    NARCIS (Netherlands)

    Fendrich, M.; Wagner, Th.; Stöhr, M.; Möller, R.

    2006-01-01

    If copper phthalocyanine (CuPc) molecules are deposited on a Au(111) surface covered with a monolayer of C60, the molecules are found to adsorb individually onto the close-packed layer of C60. As the adsorption site of the CuPc is not symmetric with respect to the underlying C60 layer, the CuPc

  14. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Molecule Matters van der Waals Molecules - Rg•••HF Complexes are Debye Molecules! E Arunan. Feature Article Volume 15 Issue 7 July 2010 pp 667-674. Fulltext. Click here to view fulltext PDF. Permanent link:

  15. 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

  16. 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)

  17. Removal of adsorbent particles od copper ions by Jet flotation

    International Nuclear Information System (INIS)

    Santander, M.; Tapia, P.; Pavez, O.; Valderrama, L.; Guzman, D.

    2009-01-01

    The present study shows the results obtained on the removal of copper ions from synthetic effluents by using the adsorbent particles flotation technique (APF) in a Jet flotation cell (Jameson type). In a typical experimental run, a mineral with high quartz content was used as adsorbent particles in the adsorption and flotation experiments, to determine optimal pH conditions, adsorbent particles concentration; flotation reagents dosage and air/effluent flow ratio for applying in the Jet cell to maximize the efficiency of copper ions adsorptions and the removal of particles adsorbents containing the absorbed copper ions. The results indicate the at pH>7 and at adsorbent particles concentration of 2 kg.m - 3, 99% of copper ions is adsorbed and, when the air/effluent flow ratio applied in the Jet cell is 0,2, 98% of absorbent particles containing the adsorbed copper ions is removed. (Author) 39 refs.

  18. Adsorption of different amphiphilic molecules onto polystyrene latices.

    Science.gov (United States)

    Jódar-Reyes, A B; Ortega-Vinuesa, J L; Martín-Rodríguez, A

    2005-02-15

    In order to know the influence of the surface characteristics and the chain properties on the adsorption of amphiphilic molecules onto polystyrene latex, a set of experiments to study the adsorption of ionic surfactants, nonionic surfactants and an amphiphilic synthetic peptide on different latex dispersions was performed. The adsorbed amount versus the equilibrium surfactant concentration was determined. The main adsorption mechanism was the hydrophobic attraction between the nonpolar tail of the molecule and the hydrophobic regions of the latex surface. This attraction overcame the electrostatic repulsion between chains and latex surface with identical charge sign. However, the electrostatic interactions chain-surface and chain-chain also played a role. General patterns for the adsorption of ionic chains on charged latex surfaces could be established. Regarding the shape, the isotherms presented different plateaus corresponding to electrostatic effects and conformational changes. The surfactant size also affects the adsorption results: the higher the hydrophilic moiety in the surfactant molecule the lower the adsorbed amount.

  19. Reaction of Br2 with adsorbed CO on Pt, studied by the surface interrogation mode of scanning electrochemical microscopy.

    Science.gov (United States)

    Wang, Qian; Rodríguez-López, Joaquín; Bard, Allen J

    2009-12-02

    Scanning electrochemical microscopy surface interrogation (SI-SECM) in the cyclic voltammetry mode was successfully used to detect and quantify adsorbed CO on a Pt electrode by reaction with electrogenerated Br(2). The two-electrode setup used in this new technique allowed the production of Br(2) on an interrogator tip, which reported a transient positive feedback above a Pt substrate at open circuit as an indication of the reactivity of this halogen with CO((ads)). Br(-) and CO(2) are shown to be the main products of the reaction (in the absence of O(2)), which may involve the formation of bromophosgene as a hydrolyzable intermediate. Under saturation conditions, CO((ads)) was reproducibly quantified at the polycrystalline Pt surface with theta(CO) approximately = 0.5. The reaction is shown to be blocked by the action of pre-adsorbed cyanide, which demonstrates the surface character of the process. The formation of CO(2) as an end product was further tested in a bulk experiment: addition of Pt black to a mixture of Br(2) in 0.5 M H(2)SO(4) through which CO was bubbled gave a precipitate of BaCO(3) in a saturated solution of Ba(OH)(2). The use of SI-SECM allowed access to a reaction that would otherwise be difficult to prove through conventional electrochemistry on a single electrode.

  20. Collisions of halogen (2P) and rare gas (1S) atoms

    International Nuclear Information System (INIS)

    Becker, C.H.

    1978-12-01

    Differential cross sections I (THETA) at several collision energies measured in crossed molecular beam experiments are reported for several combinations of halogen atoms ( 2 P) scattered off rare gas-rare gas atoms ( 1 S 0 ), namely, F + Ne, F + Ar, F + Kr, F + Xe, C1 + Xe. The scattering is described by an elastic model appropriate to Hund's case c coupling. With the use of this model, the X 1/2, I 3/2, and II 1/2 interaction potential energy curves are derived by fitting calculated differential cross sections, based on analytic representations of the potentials, to the data. The F - Xe X 1/2 potential shows a significant bonding qualitatively different than for the other F-rare gases. The I 3/2 and II 1/2 potentials closely resemble the van der Waals interactions of the one electron richer ground state rare gas-rare gas systems. Coupled-channel scattering calculations are carried out for F + Ar, F + Xe, and C1 + Xe using the realistic potential curves derived earlier. The results justify the use of the elastic model, and give additional information on intramultiplet and intermultiplet transitions. The transitions are found to be governed by the crossing of the two Ω = 1/2 potentials in the complex plane. The measured I (theta) and I (THETA) derived from the coupled-channel computations show small oscillations or perturbations (Stueckelberg oscillations) though quantitative agreement is not obtained.The nature of the anomalous F - Xe X 1/2 potential is discussed as is the approximation of a constant spin orbit coupling over the experimentally accessible range of internuclear distances for these open shell molecules. 55 references

  1. Structural, electronic, and magnetic properties of pristine and oxygen-adsorbed graphene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Miwa, R.H.; Veiga, R.G.A. [Instituto de Fisica, Universidade Federal de Uberlandia, Caixa Postal 593, CEP 38400-902, Uberlandia, MG (Brazil); Srivastava, G.P., E-mail: gps@excc.ex.ac.uk [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

    2010-07-15

    The structural, electronic and magnetic properties of pristine and oxygen-adsorbed (3,0) zigzag and (6,1) armchair graphene nanoribbons have been investigated theoretically, by employing the ab initio pseudopotential method within the density functional scheme. The zigzag nanoribbon is more stable with antiferromagnetically coupled edges, and is semiconducting. The armchair nanoribbon does not show any preference for magnetic ordering and is semiconducting. The oxygen molecule in its triplet state is adsorbed most stably at the edge of the zigzag nanoribbon. The Stoner metallic behaviour of the ferromagnetic nanoribbons and the Slater insulating (ground state) behaviour of the antiferromagnetic nanoribbons remain intact upon oxygen adsorption. However, the local magnetic moment of the edge carbon atom of the ferromagnetic zigzag ribbon is drastically reduced, due to the formation of a spin-paired C-O bond.

  2. Aggregate formation of eosin-Y adsorbed on nanocrystalline TiO2 films

    Science.gov (United States)

    Yaguchi, Kaori; Furube, Akihiro; Katoh, Ryuzi

    2012-11-01

    We have studied the adsorption of eosin-Y on nanocrystalline TiO2 films with two different solvents namely acetonitrile (ACN) and ethanol (EtOH). A Langmuir-type adsorption isotherm was observed with ACN. In contrast, a Freundlich-type adsorption isotherm was observed with EtOH, suggesting that EtOH molecules co-adsorbed on TiO2 surface. Absorption spectra of the dye adsorbed films clearly show aggregate formation at high concentrations of dye in the solutions. From the analysis of the spectra, we conclude that head-to-tail type aggregates are observed with ACN, whereas various types of aggregates, including H-type and head-to-tail type aggregates, are observed with EtOH.

  3. Comparative study of normal and branched alkane monolayer films adsorbed on a solid surface. I. Structure

    DEFF Research Database (Denmark)

    Enevoldsen, Ann Dorrit; Hansen, Flemming Yssing; Diama, A.

    2007-01-01

    their backbone and squalane has, in addition, six methyl side groups. Upon adsorption, there are significant differences as well as similarities in the behavior of these molecular films. Both molecules form ordered structures at low temperatures; however, while the melting point of the two-dimensional (2D......The structure of a monolayer film of the branched alkane squalane (C30H62) adsorbed on graphite has been studied by neutron diffraction and molecular dynamics (MD) simulations and compared with a similar study of the n-alkane tetracosane (n-C24H52). Both molecules have 24 carbon atoms along...... temperature. The neutron diffraction data show that the translational order in the squalane monolayer is significantly less than in the tetracosane monolayer. The authors' MD simulations suggest that this is caused by a distortion of the squalane molecules upon adsorption on the graphite surface. When...

  4. 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.

  5. Diffusion Monte Carlo simulations of gas phase and adsorbed D2-(H2)n clusters

    Science.gov (United States)

    Curotto, E.; Mella, M.

    2018-03-01

    We have computed ground state energies and analyzed radial distributions for several gas phase and adsorbed D2(H2)n and HD(H2)n clusters. An external model potential designed to mimic ionic adsorption sites inside porous materials is used [M. Mella and E. Curotto, J. Phys. Chem. A 121, 5005 (2017)]. The isotopic substitution lowers the ground state energies by the expected amount based on the mass differences when these are compared with the energies of the pure clusters in the gas phase. A similar impact is found for adsorbed aggregates. The dissociation energy of D2 from the adsorbed clusters is always much higher than that of H2 from both pure and doped aggregates. Radial distributions of D2 and H2 are compared for both the gas phase and adsorbed species. For the gas phase clusters, two types of hydrogen-hydrogen interactions are considered: one based on the assumption that rotations and translations are adiabatically decoupled and the other based on nonisotropic four-dimensional potential. In the gas phase clusters of sufficiently large size, we find the heavier isotopomer more likely to be near the center of mass. However, there is a considerable overlap among the radial distributions of the two species. For the adsorbed clusters, we invariably find the heavy isotope located closer to the attractive interaction source than H2, and at the periphery of the aggregate, H2 molecules being substantially excluded from the interaction with the source. This finding rationalizes the dissociation energy results. For D2-(H2)n clusters with n ≥12 , such preference leads to the desorption of D2 from the aggregate, a phenomenon driven by the minimization of the total energy that can be obtained by reducing the confinement of (H2)12. The same happens for (H2)13, indicating that such an effect may be quite general and impact on the absorption of quantum species inside porous materials.

  6. LEED crystallography studies of the structure of clean and adsorbate-covered Ir, Pt and Rh crystal surfaces

    International Nuclear Information System (INIS)

    Koestner, R.J.

    1982-08-01

    There have only been a few Low Energy Electron Diffraction (LEED) intensity analyses carried out to determine the structure of molecules adsorbed on metal surfaces; most surface crystallography studies concentrated on the structure of clean unreconstructed or atomic adsorbate-covered transition metal faces. The few molecular adsorption systems already investigated by dynamical LEED are CO on Ni(100), Cu(100) and Pd(100) as well as C 2 H 2 and C 2 H 4 adsorbed on Pt(111). The emphasis of this thesis research has been to extend the applicability of LEED crystallography to the more complicated unit cells found in molecular overlayers on transition metals or in there constructed surfaces of clean transition metals

  7. LEED crystallography studies of the structure of clean and adsorbate-covered Ir, Pt and Rh crystal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Koestner, R.J.

    1982-08-01

    There have only been a few Low Energy Electron Diffraction (LEED) intensity analyses carried out to determine the structure of molecules adsorbed on metal surfaces; most surface crystallography studies concentrated on the structure of clean unreconstructed or atomic adsorbate-covered transition metal faces. The few molecular adsorption systems already investigated by dynamical LEED are CO on Ni(100), Cu(100) and Pd(100) as well as C/sub 2/H/sub 2/ and C/sub 2/H/sub 4/ adsorbed on Pt(111). The emphasis of this thesis research has been to extend the applicability of LEED crystallography to the more complicated unit cells found in molecular overlayers on transition metals or in there constructed surfaces of clean transition metals.

  8. Identification and quantification of the halogenated natural product BC-3

    Energy Technology Data Exchange (ETDEWEB)

    Melcher, J.; Olbrich, D.; Vetter, W. [Hohenheim Univ., Stuttgart (Germany). Inst. fuer Lebensmittelchemie; Marsh, G. [Stockholm Univ. (Sweden). Dept. of Environmental Chemistry; Gaus, C.; Mueller, J.F. [National Research Centre for Environmental Toxicology, Coopers Plains (Australia)

    2004-09-15

    Halogenated natural products (HNPs) of marine origin are increasingly recognized as critical residues in foodstuff (e. g. fish) and environmental samples (e. g. marine mammals and birds). Some of these HNPs (Q1, MHC-1, BC-2, and HDBPs including BC-10) were detected in diverse fish and marine mammal samples at concentrations sometimes exceeding those of PCBs, DDT, and other anthropogenic pollutants. Recent studies with marine mammal samples from Australia led to the detection of six abundant HNPs (Q1, BC-1, BC-2, BC-3, BC-10, and BC-11). In the meantime, Q1 was identified as heptachloro-1{sup '}-methyl-1,2{sup '}-bipyrrole, BC-2 as 4,6-dibromo-2-(2{sup '},4{sup '}-dibromo)phenoxyanisole, BC- 10 as 1,1{sup '}-dimethyl-3,3{sup '},4,4{sup '}-tetrabromo-5,5{sup '}-dichloro-2,2{sup '}-bipyrrole, and BC-11 as 3,5-dibromo- 2-(3{sup '},5{sup '}-dibromo,2{sup '}-methoxy)phenoxyanisole. However the identity of BC-1 and BC-3 remained unclear. The goal of the present study was the identification of BC-3. The tetrabromo compound BC-3 has previously been detected in marine mammals from four continents. Furthermore, we attempted establishing quantitative concentrations in diverse marine biota samples.

  9. 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.

  10. Development of adsorbents for recovery of uranium from seawater

    International Nuclear Information System (INIS)

    Egawa, Hiroaki; Furusaki, Shintaro.

    1987-01-01

    The largest subject for putting the extraction of uranium from seawater in practical use is the development of high performance adsorbents for uranium. In this paper, the way of thinking about the development of adsorbents for extracting uranium from seawater and the recent reports on this subject are described. Next, the research on the adsorbing capacity and adsorbing rate of the adsorbents developed so far is summarized, and the way of thinking about the evaluation of adsorbent performance which is the base of the design of a system for extracting uranium from seawater is explained, taking amidoxime type adsorbent as the example. For Japan where energy resources are scant, the uranium contained in seawater, which is estimated to be about 4.2 billion t, is the most luring important element. Uranium is contained in seawater is very low concentration of 3 ppb, and exists as anion complex salt. In 1960s, the Harwell Atomic Energy Research Establishment in UK found out that titanium oxide hydrate is the most promising as the adsorbent. Also a number of organic absorbents have been developed. In order to bring adsorbents in contact with seawater, pumping, ocean current and wave force are utilized. Adsorbents are in spherical, fiber and film forms, and held as fixed beds and fluidized beds. (Kako, I.) 48 refs

  11. Synthesis of Isotactic-block-Syndiotactic Poly(methyl Methacrylate via Stereospecific Living Anionic Polymerizations in Combination with Metal-Halogen Exchange, Halogenation, and Click Reactions

    Directory of Open Access Journals (Sweden)

    Naoya Usuki

    2017-12-01

    Full Text Available Isotactic (it- and syndiotactic (st- poly(methyl methacrylates (PMMAs form unique crystalline stereocomplexes, which are attractive from both fundamental and application viewpoints. This study is directed at the efficient synthesis of it- and st-stereoblock (it-b-st- PMMAs via stereospecific living anionic polymerizations in combination with metal-halogen exchange, halogenation, and click reactions. The azide-capped it-PMMA was prepared by living anionic polymerization of MMA, which was initiated with t-BuMgBr in toluene at –78 °C, and was followed by termination using CCl4 as the halogenating agent in the presence of a strong Lewis base and subsequent azidation with NaN3. The alkyne-capped st-PMMA was obtained by living anionic polymerization of MMA, which was initiated via an in situ metal-halogen exchange reaction between 1,1-diphenylhexyl lithium and an α-bromoester bearing a pendent silyl-protected alkyne group. Finally, copper-catalyzed alkyne-azide cycloaddition (CuAAC between these complimentary pairs of polymers resulted in a high yield of it-b-st-PMMAs, with controlled molecular weights and narrow molecular weight distributions. The stereocomplexation was evaluated in CH3CN and was affected by the block lengths and ratios.

  12. 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.

  13. Theoretical Insight of Physical Adsorption for a Single Component Adsorbent + Adsorbate System: II. The Henry Region

    KAUST Repository

    Chakraborty, Anutosh; Saha, Bidyut Baran; Ng, Kim Choon; Koyama, Shigeru; Srinivasan, Kandadai

    2009-01-01

    evaluated and compared with experimental data. It is found that the adsorbents with higher specific surface areas tend to possess lower heat of adsorption (ΔH°) at the Henry regime. In this paper, we have established the definitive relation between Ai and ΔH

  14. Natural adsorbents of dyes from aqueous solution

    Science.gov (United States)

    Rahmani, Meryem; El Hajjaji, souad; Dahchour, Abdelmalek; El M'Rabet, Mohammadine

    2017-04-01

    Contamination of natural waters is a current environmental problem and lot of work has been done to find methods for its, prevention and remediation such as ionic exchange, adsorption on active carbon, filtration, electrolysis, biodegradation …etc. Adsorption is one of the most applied methods according to its effectiveness and easy management. Some adsorbents with good properties such as active alumina, zeolites, crop residues … etc, are suitable to substitute usual active carbon. This study aimed at the removal of dyes using oil shale as natural support, and its optimization by factorial experiment. Three factors were considered namly:pollutant concentration, pH and weight of the adsorbent. Tests have been performed with cationic and anionic dyes. Experimental results show that pseudo-first-order kinetic model provided the best fit to the experimental data for the adsorption by the oil shale. Langmuir, Freundlich and Temkin isotherm models were tested to fit experimental data, the adsorption equilibrium was well described by Freundlich isotherm for methylorange and Temkin for methyl blue. Analysis were completed by oil shale characterization educing XRD, IR, XRF techniques, and cationic exchange capacity.

  15. Optimizing heterosurface adsorbent synthesis for liquid chromatography

    Science.gov (United States)

    Bogoslovskii, S. Yu.; Serdan, A. A.

    2016-03-01

    The structural and geometric parameters of a silica matrix (SM) for the synthesis of heterosurface adsorbents (HAs) are optimized. Modification is performed by shielding the external surfaces of alkyl-modified silica (AS) using human serum albumin and its subsequent crosslinking. The structural and geometric characteristics of the SM, AS, and HA are measured via low-temperature nitrogen adsorption. It is found that the structural characteristics of AS pores with diameters D 9 nm reduces significantly due to adsorption of albumin. It is concluded that silica gel with a maximum pore size distribution close to 5 nm and a minimal proportion of pores with D > 9 nm is optimal for HA synthesis; this allows us to achieve the greatest similarity between the chromatographic retention parameters for HA and AS. The suitability of the synthesized adsorbents for analyzing drugs in biological fluids through direct sample injection is confirmed by chromatography. It was found that the percentage of the protein fraction detected at the outlet of the chromatographic column is 98%.

  16. Surface-enhanced Raman spectrum of Gly-Gly adsorbed on the silver colloidal surface

    Science.gov (United States)

    Xiaojuan, Yuan; Huaimin, Gu; Jiwei, Wu

    2010-08-01

    Raman and SERS spectra of homodipeptide Gly-Gly and Gly were recorded and compared in this paper, and band assignment for the functional groups contained in these molecules was analyzed in detail. Time-dependent and pH-dependent SERS spectra of Gly-Gly molecule adsorbed on nano-colloidal silver surface were also studied. The time-dependent SERS spectra of Gly-Gly are characterized by the increase in intensity of bands primarily representing the vibrational signatures emanating from the amino and amide moiety of Gly-Gly molecule. It is found that the adsorption style of Gly-Gly on the silver colloid changes as time goes on; at 5 min after adding the sample to the silver colloid, Gly-Gly adsorbs on silver surface firstly through the carboxylate, amino and amide groups, and then the carboxylate group is far away from the silver surface at 10 min to 3 days. The SERS variation of Gly-Gly with the change of pH suggests that the adsorption style is pH-dependent, the different adsorption behavior of the Gly-Gly occurs on silver surface at different pH values.

  17. New type of amidoxime-group-containing adsorbent for the recovery of uranium from seawater. III. Recycle use of adsorbent

    International Nuclear Information System (INIS)

    Omichi, H.; Katakai, A.; Sugo, T.; Okamoto, J.

    1986-01-01

    An amidoxime-group adsorbent for recovering uranium from seawater was made by radiation-induced graft polymerization of acrylonitrile onto polymeric fiber, followed by amidoximation. Uranium adsorption of the adsorbent contacted with seawater in a column increased with the increase in flow rate, then leveled off. The relationship between uranium adsorption in a batch process and the ratio of the amount of seawater to that of adsorbent was found to be effective in evaluating adsorbent contacted with any amount of seawater. The conditioning of the adsorbent with an alkaline solution at higher temperature (∼80 0 C) after the acid desorption recovered the adsorption ability to the original level. This made it possible to apply the adsorbent to recycle use. On the other hand, the adsorbent conditioned at room temperature or that without conditioning lost adsorption ability during recycle use. The increase in water uptake was observed as one of the physical changes produced during recycle use of the alkaline-conditioned adsorbent, while the decrease in water uptake was observed with the unconditioned adsorbent. The IR spectra of the adsorbent showed a probability of reactions of amidoxime groups with acid and alkaline solutions, which can explain the change in uranium adsorption during the adsorption-desorption cycle

  18. Organized single-molecule magnets: direct observation of new Mn12 derivatives on gold

    International Nuclear Information System (INIS)

    Cornia, A.; Fabretti, A.C.; Pacchioni, M.; Zobbi, L.; Bonacchi, D.; Caneschi, A.; Gatteschi, D.; Biagi, R.; Del Pennino, U.; De Renzi, V.; Gurevich, L.; Zant, H.S.J. van der

    2004-01-01

    Gold adsorbates of the dodecamanganese(III,IV) single-molecule magnet (SMM) [Mn 12 O 12 (L) 16 (H 2 O) 4 ] where L=16-(acetylthio)hexadecanoate have been prepared and investigated by X-ray photoelectron spectroscopy and scanning tunneling microscopy (STM). The successful imaging of Mn 12 molecules by STM represents a first step toward the magnetic addressing of individual SMMs and the development of molecule-based devices for magnetic information storage

  19. On determination of the dynamics of hydrocarbon molecules on catalyst's surfaces by means of neutron scattering

    International Nuclear Information System (INIS)

    Stockmeyer, R.

    1976-01-01

    The intensity distribution of slow neutrons scattered by adsorbed hydrocarbon molecules contains information on the dynamics of the molecules. In this paper the scattering law for incoherently scattering molecules is derived taking into account the very different mobility perpendicular and parallel to the surface. In contrast to the well known scattering law of threedimensionally diffusing particles the scattering law for twodimensional diffusion diverges logarithmically at zero energy transfer. Conclusions relevant to the interpretation of neutron scattering data are discussed. (orig.) [de

  20. Volumetric interpretation of protein adsorption: interfacial packing of protein adsorbed to hydrophobic surfaces from surface-saturating solution concentrations.

    Science.gov (United States)

    Kao, Ping; Parhi, Purnendu; Krishnan, Anandi; Noh, Hyeran; Haider, Waseem; Tadigadapa, Srinivas; Allara, David L; Vogler, Erwin A

    2011-02-01

    The maximum capacity of a hydrophobic adsorbent is interpreted in terms of square or hexagonal (cubic and face-centered-cubic, FCC) interfacial packing models of adsorbed blood proteins in a way that accommodates experimental measurements by the solution-depletion method and quartz-crystal-microbalance (QCM) for the human proteins serum albumin (HSA, 66 kDa), immunoglobulin G (IgG, 160 kDa), fibrinogen (Fib, 341 kDa), and immunoglobulin M (IgM, 1000 kDa). A simple analysis shows that adsorbent capacity is capped by a fixed mass/volume (e.g. mg/mL) surface-region (interphase) concentration and not molar concentration. Nearly analytical agreement between the packing models and experiment suggests that, at surface saturation, above-mentioned proteins assemble within the interphase in a manner that approximates a well-ordered array. HSA saturates a hydrophobic adsorbent with the equivalent of a single square or hexagonally-packed layer of hydrated molecules whereas the larger proteins occupy two-or-more layers, depending on the specific protein under consideration and analytical method used to measure adsorbate mass (solution depletion or QCM). Square or hexagonal (cubic and FCC) packing models cannot be clearly distinguished by comparison to experimental data. QCM measurement of adsorbent capacity is shown to be significantly different than that measured by solution depletion for similar hydrophobic adsorbents. The underlying reason is traced to the fact that QCM measures contribution of both core protein, water of hydration, and interphase water whereas solution depletion measures only the contribution of core protein. It is further shown that thickness of the interphase directly measured by QCM systematically exceeds that inferred from solution-depletion measurements, presumably because the static model used to interpret solution depletion does not accurately capture the complexities of the viscoelastic interfacial environment probed by QCM. Copyright © 2010

  1. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    International Nuclear Information System (INIS)

    Tsouris, Costas; Mayes, Richard T.; Janke, Christopher James; Dai, Sheng; Das, S.; Liao, W.P.; Kuo, Li-Jung; Wood, Jordana; Gill, Gary; Byers, Maggie Flicker; Schneider, Eric

    2015-01-01

    The Fuel Resources program of the Fuel Cycle Research and Development program of the Office of Nuclear Energy (NE) is focused on identifying and implementing actions to assure that nuclear fuel resources are available in the United States. An immense source of uranium is seawater, which contains an estimated amount of 4.5 billion tonnes of dissolved uranium. This unconventional resource can provide a price cap and ensure centuries of uranium supply for future nuclear energy production. NE initiated a multidisciplinary program with participants from national laboratories, universities, and research institutes to enable technical breakthroughs related to uranium recovery from seawater. The goal is to develop advanced adsorbents to reduce the seawater uranium recovery technology cost and uncertainties. Under this program, Oak Ridge National Laboratory (ORNL) has developed a new amidoxime-based adsorbent of high surface area, which tripled the uranium capacity of leading Japanese adsorbents. Parallel efforts have been focused on the optimization of the physicochemical and operating parameters used during the preparation of the adsorbent for deployment. A set of parameters that need to be optimized are related to the conditioning of the adsorbent with alkali solution, which is necessary prior to adsorbent deployment. Previous work indicated that alkali-conditioning parameters significantly affect the adsorbent performance. Initiated in 2014, this study had as a goal to determine optimal parameters such as base type and concentration, temperature, and duration of conditioning that maximize the uranium adsorption performance of amidoxime functionalized adsorbent, while keeping the cost of uranium production low. After base-treatment at various conditions, samples of adsorbent developed at ORNL were tested in this study with batch simulated seawater solution of 8-ppm uranium concentration, batch seawater spiked with uranium nitrate at 75-100 ppb uranium, and continuous

  2. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mayes, Richard T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Janke, Christopher James [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dai, Sheng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Das, S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liao, W. -P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wood, Jordana [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gill, Gary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Byers, Maggie Flicker [Univ. of Texas, Austin, TX (United States); Schneider, Eric [Univ. of Texas, Austin, TX (United States)

    2015-09-30

    The Fuel Resources program of the Fuel Cycle Research and Development program of the Office of Nuclear Energy (NE) is focused on identifying and implementing actions to assure that nuclear fuel resources are available in the United States. An immense source of uranium is seawater, which contains an estimated amount of 4.5 billion tonnes of dissolved uranium. This unconventional resource can provide a price cap and ensure centuries of uranium supply for future nuclear energy production. NE initiated a multidisciplinary program with participants from national laboratories, universities, and research institutes to enable technical breakthroughs related to uranium recovery from seawater. The goal is to develop advanced adsorbents to reduce the seawater uranium recovery technology cost and uncertainties. Under this program, Oak Ridge National Laboratory (ORNL) has developed a new amidoxime-based adsorbent of high surface area, which tripled the uranium capacity of leading Japanese adsorbents. Parallel efforts have been focused on the optimization of the physicochemical and operating parameters used during the preparation of the adsorbent for deployment. A set of parameters that need to be optimized are related to the conditioning of the adsorbent with alkali solution, which is necessary prior to adsorbent deployment. Previous work indicated that alkali-conditioning parameters significantly affect the adsorbent performance. Initiated in 2014, this study had as a goal to determine optimal parameters such as base type and concentration, temperature, and duration of conditioning that maximize the uranium adsorption performance of amidoxime functionalized adsorbent, while keeping the cost of uranium production low. After base-treatment at various conditions, samples of adsorbent developed at ORNL were tested in this study with batch simulated seawater solution of 8-ppm uranium concentration, batch seawater spiked with uranium nitrate at 75-100 ppb uranium, and continuous

  3. Creation of the technical adsorbent from local raw materials

    International Nuclear Information System (INIS)

    Isobaev, M.D.; Davlatnazarova, M.D.; Abdullaev, T.H.

    2016-01-01

    The results showed the possibility of obtaining effective adsorbents of walnut shell and the sunflower for environmental purposes, in particular for the purification of polluted waters from heavy metals. It has been shown, that 1 g of walnut shell adsorbent can adsorb on its surface ions of lead in amount of 47% by weight. The dependence of the adsorption activity of the semi-coke received from walnut shell from particle size and concentration of the solution. (author)

  4. Analysis of Halogen-Mercury Reactions in Flue Gas

    Energy Technology Data Exchange (ETDEWEB)

    Paula Buitrago; Geoffrey Silcox; Constance Senior; Brydger Van Otten

    2010-01-01

    Oxidized mercury species may be formed in combustion systems through gas-phase reactions between elemental mercury and halogens, such as chorine or bromine. This study examines how bromine species affect mercury oxidation in the gas phase and examines the effects of mixtures of bromine and chlorine on extents of oxidation. Experiments were conducted in a bench-scale, laminar flow, methane-fired (300 W), quartz-lined reactor in which gas composition (HCl, HBr, NO{sub x}, SO{sub 2}) and temperature profile were varied. In the experiments, the post-combustion gases were quenched from flame temperatures to about 350 C, and then speciated mercury was measured using a wet conditioning system and continuous emissions monitor (CEM). Supporting kinetic calculations were performed and compared with measured levels of oxidation. A significant portion of this report is devoted to sample conditioning as part of the mercury analysis system. In combustion systems with significant amounts of Br{sub 2} in the flue gas, the impinger solutions used to speciate mercury may be biased and care must be taken in interpreting mercury oxidation results. The stannous chloride solution used in the CEM conditioning system to convert all mercury to total mercury did not provide complete conversion of oxidized mercury to elemental, when bromine was added to the combustion system, resulting in a low bias for the total mercury measurement. The use of a hydroxylamine hydrochloride and sodium hydroxide solution instead of stannous chloride showed a significant improvement in the measurement of total mercury. Bromine was shown to be much more effective in the post-flame, homogeneous oxidation of mercury than chlorine, on an equivalent molar basis. Addition of NO to the flame (up to 400 ppmv) had no impact on mercury oxidation by chlorine or bromine. Addition of SO{sub 2} had no effect on mercury oxidation by chlorine at SO{sub 2} concentrations below about 400 ppmv; some increase in mercury oxidation

  5. 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.

  6. 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.

  7. WGS-Adsorbent Reaction Studies at Laboratory Scale

    International Nuclear Information System (INIS)

    Marano, M.; Torreiro, Y.

    2014-01-01

    This document reports the most significant results obtained during the experimental work performed under task WGS adsorbent experimental studies within CAPHIGAS project (National Research Plan 2008-2011, ref: ENE2009-08002). The behavior of the binary adsorbent-catalyst system which will be used in the hybrid system is described in this document. Main results reported here were used during the design and development of the hybrid system adsorbent catalyst- membrane proposed in the CAPHIGAS project. The influence of main operating parameters and the optimized volume ratio adsorbent-catalyst are also presented in this report. (Author)

  8. Neutralization of Rubidium Adsorbate Electric Fields by Electron Attachment

    Energy Technology Data Exchange (ETDEWEB)

    Sedlacek, J. A. [Univ. of Oklahoma, Norman, OK (United States); Kim, E. [Univ. of Nevada, Las Vegas, NV (United States); Rittenhouse, S. T. [Western Washington Univ., Bellingham, WA (United States); US Naval Academy, Annapolis, MD (United States); Weck, Philippe F [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sadeghpour, H. R. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Shaffer, J. P. [Univ. of Oklahoma, Norman, OK (United States)

    2015-10-01

    We investigate the (0001) surface of single crystal quartz with a submonolayer of Rb adsorbates. Using Rydberg atom electromagnetically induced transparency, we investigate the electric elds resulting from Rb adsorbed on the quartz surface, and measure the activation energy of the Rb adsorbates. We show that the Rb induces a negative electron affnity (NEA) on the quartz surface. The NEA surface allows for low energy electrons to bind to the surface and cancel the electric eld from the Rb adsorbates. Our results have implications for integrating Rydberg atoms into hybrid quantum systems and the fundamental study of atom-surface interactions, as well as applications for electrons bound to a 2D surface.

  9. Mobility of adsorbed Cry1Aa insecticidal toxin from Bacillus thuringiensis (Bt) on montmorillonite measured by fluorescence recovery after photobleaching (FRAP)

    Science.gov (United States)

    Helassa, Nordine; Daudin, Gabrielle; Noinville, Sylvie; Janot, Jean-Marc; Déjardin, Philippe; Staunton, Siobhán; Quiquampoix, Hervé

    2010-06-01

    The insecticidal toxins produced by genetically modified Bt crops are introduced into soil through root exudates and tissue decomposition and adsorb readily on soil components, especially on clays. This immobilisation and the consequent concentration of the toxins in "hot spots" could increase the exposure of soil organisms. Whereas the effects on non-target organisms are well documented, few studies consider the migration of the toxin in soil. In this study, the residual mobility of Bt Cry1Aa insecticidal toxin adsorbed on montmorillonite was assessed using fluorescence recovery after photobleaching (FRAP). This technique, which is usually used to study dynamics of cytoplasmic and membrane molecules in live cells, was applied for the first time to a protein adsorbed on a finely divided swelling clay mineral, montmorillonite. No mobility of adsorbed toxin was observed at any pH and at different degrees of surface saturation.

  10. Simultaneous determination of radioactive halogen isotopes and 99Tc

    International Nuclear Information System (INIS)

    Kabai, E.; Vajda, N.; Gaca, P.

    2003-01-01

    The purpose of this study was to develop a simplified method for simultaneous determination of radiologically important halogen isotopes and 99 Tc from different types of samples like environmental, biological and waste samples. Due to their long half-lives (longer than 10 5 years) they play important role in the nuclear cycle, especially in environmental monitoring and protection. For a rapid response in the evaluation of 129 I, 36 Cl and 99 Tc contamination levels of these samples it is advantageous to combine the existing individual methods. According to the present procedure, iodine, chlorine and technetium are separated selectively from the same sample aliquot followed by the β spectrometry of the purified fractions. Increased sensitivities can be achieved by neutron activation (NA) especially in the case of 129 I. Our work intends to solve the problem by combining the well-known hot acidic distillation method for iodine separation with the organic extraction process characteristic for technetium separation. The major objective of the work was to separate the disturbing halides from iodine. For this purpose a selective oxidant was applied. For the sample destruction and fractionated distillation an air flow-through installation was used with hot concentrated sulphuric and nitric acids. The trap for iodine contained 3 M NaOH solution. After iodine separation the trap was exchanged for a new one containing the same solution for trapping chlorine or bromine with an addition of 0.01 M KMnO 4 solution as an oxidative agent. As expected, the main part of technetium was contained in the acidic residue after distillation. Tc purification was performed by organic extraction with TBP and TEVA column. (author)

  11. 13C separation by IRMPD of halogenated difluoromethanes

    International Nuclear Information System (INIS)

    Ma Peihua; Chen Guancheng; Wu Bin; Liu Julin; Jing Yan; Chu Minxiong; Arai, Shigeyoshi.

    1995-01-01

    Isotopically-selective consecutive two-stage infrared multiphoton dissociation (IRMPD) of halogenated difluoromethanes in the presence of scavengers produces carbon-13 over 95 %. The reaction mechanism for the IRMPD of mixture of CHClF 2 and HI can be explained by a series of first-order dissociation reactions and followed radical-scavenger reactions occurred in a continuous irradiation procedure. Furthermore, 13 C enrichment at laboratory scaling-up level by the 13 C selective IRMPD of CHClF 2 /Br 2 mixture has been investigated in a flow reactor. The 13 C production rates, 13 C atomic fractions in the CBr 2 F 2 products and 13 C depletions in the CHClF 2 reactants at different flow rates and laser repetition frequencies were examined to optimize the parameters suitable for large-scale production of carbon isotope. The data obtained from the flow tests demonstrated a 40 mg h -1 production rate for CB 2 F 2 at 65 % carbon-13 by using a 40 W (4J, 10 Hz) laser beam focused with a lens of focal length 120 cm. If a reliable TEA CO 2 laser can be operated with 100 W (10 J, 10 Hz) output, the production rate of CBr 2 F 2 for carbon-13 at 60 % can attain 200 mg h -1 . The measurements of spatial profile of focused laser beam imply a 2 g h -1 production rate for the 60 % carbon-13 product for an incident power of 200 W (20 J, 10 Hz). (author)

  12. Scanning tunneling microscopy I general principles and applications to clean and adsorbate-covered surfaces

    CERN Document Server

    Wiesendanger, Roland

    1992-01-01

    Scanning Tunneling Microscopy I provides a unique introduction to a novel and fascinating technique that produces beautiful images of nature on an atomic scale. It is the first of three volumes that together offer a comprehensive treatment of scanning tunneling microscopy, its diverse applications, and its theoretical treatment. In this volume the reader will find a detailed description of the technique itself and of its applications to metals, semiconductors, layered materials, adsorbed molecules and superconductors. In addition to the many representative results reviewed, extensive references to original work will help to make accessible the vast body of knowledge already accumulated in this field.

  13. Raman spectroscopy of adsorbed water in clays: first attempt at band assignment

    Energy Technology Data Exchange (ETDEWEB)

    Ligny, Dominique de; Guillaud, Emmanuel [Institut Lumiere Matiere, CNRS, Universite Lyon 1, 12 rue Ada Byron, 69622 Villeurbanne (France); Gailhanou, Helene; Blanc, Philippe [BRGM, Service D3E, 3 avenue Claude Guillemin, 45000 Orleans (France)

    2013-07-01

    Raman spectroscopy can be a useful tool to determine water content within clays, or even in highly saturated solutions. The following assignment is proposed for the OH region of SAz-2: the two large bands at 3260 and 3475 cm{sup -1} are assigned to water in pores, the first one to water molecules coordinated to the interlayer cations, and the second one to structural Al-OH groups The band at 3600 cm{sup -1} is therefore more likely related to adsorbed water on the clay surface. Simple intensity ratios of these different bands give good estimates of water content. (authors)

  14. Theory and Monte-Carlo simulation of adsorbates on corrugated surfaces

    DEFF Research Database (Denmark)

    Vives, E.; Lindgård, P.-A.

    1993-01-01

    -phase between the commensurate and incommensurate phase stabilized by defects. Special attention has been given to the study of the epitaxial rotation angles of the different phases. Available experimental data is in agreement with the simulations and with a general theory for the epitaxial rotation which takes......Phase transitions in systems of adsorbed molecules on corrugated surfaces are studied by means of Monte Carlo simulation. Particularly, we have studied the phase diagram of D2 on graphite as a function of coverage and temperature. We have demonstrated the existence of an intermediate gamma...

  15. Theoretical Insight of Physical Adsorption for a Single-Component Adsorbent + Adsorbate System: I. Thermodynamic Property Surfaces

    KAUST Repository

    Chakraborty, Anutosh

    2009-02-17

    Thermodynamic property surfaces for a single-component adsorbent + adsorbate system are derived and developed from the viewpoint of classical thermodynamics, thermodynamic requirements of chemical equilibrium, Gibbs law, and Maxwell relations. They enable us to compute the entropy and enthalpy of the adsorbed phase, the isosteric heat of adsorption, specific heat capacity, and the adsorbed phase volume thoroughly. These equations are very simple and easy to handle for calculating the energetic performances of any adsorption system. We have shown here that the derived thermodynamic formulations fill up the information gap with respect to the state of adsorbed phase to dispel the confusion as to what is the actual state of the adsorbed phase. We have also discussed and established the temperature-entropy diagrams of (i) CaCl 2-in-silica gel + water system for cooling applications, and (ii) activated carbon (Maxsorb III) + methane system for gas storage. © Copyright 2009 American Chemical Society.

  16. Influence of adsorbed hydrogen molecules on the hydrogen permeation and recycling

    International Nuclear Information System (INIS)

    Banno, T.

    1987-01-01

    Hydrogen permeation through a thin iron membrane has been measured using a molecular hydrogen gas and/or a weakly ionized rf-discharge as particle sources. Transient and steady state values of the permeation flux φ p were obtained in the regime where the surface penetration of H and the recombinative release of H 2 are rate-determining. φ p is then proportional to the flux density ψ of the particles which impinge on the membrane upstream. The proportionality factors depend on the nature (atomic or molecular) of the incident particles, on temperature (in particular for a molecular driving gas) and on the ratio of the surface recombinative release rate constants (2σk r ) u and (2σk r ) d up- and downstream, respectively. (orig.)

  17. Spectroscopy of surface adsorbed molecules (scanning tunneling microscopy). Progress report, May 1, 1985-April 30, 1986

    International Nuclear Information System (INIS)

    Coleman, R.V.

    1986-01-01

    A review of the scanning tunneling microscopy program is given. This article contains a description of the design and fabrication of the microscope in addition to description of studies which use the microscope: studies of charge-density waves and studies of tunnel junctions doped with metals and semiconductors. 48 refs., 26 figs

  18. Micro-differential thermal analysis detection of adsorbed explosive molecules using microfabricated bridges

    DEFF Research Database (Denmark)

    Senesac, Larry R.; Yi, Dechang; Greve, Anders

    2009-01-01

    Although micromechanical sensors enable chemical vapor sensing with unprecedented sensitivity using variations in mass and stress, obtaining chemical selectivity using the micromechanical response still remains as a crucial challenge. Chemoselectivity in vapor detection using immobilized selective...... layers that rely on weak chemical interactions provides only partial selectivity. Here we show that the very low thermal mass of micromechanical sensors can be used to produce unique responses that can be used for achieving chemical selectivity without losing sensitivity or reversibility. We demonstrate...

  19. Functionalized molecules studied by STM: motion, switching and reactivity

    International Nuclear Information System (INIS)

    Grill, Leonhard

    2008-01-01

    Functionalized molecules represent the central issue of molecular nanotechnology. Scanning tunnelling microscopy (STM) is a powerful method to investigate such molecules, because it allows us to image them with sub-molecular resolution when adsorbed on a surface and can be used at the same time as a tool to manipulate single molecules in a controlled way. Such studies permit deep insight into the conformational, mechanical and electronic structure and thus functionalities of the molecules. In this review, recent experiments on specially designed molecules, acting as model systems for molecular nanotechnology, are reviewed. The presented studies focus on key functionalities: lateral rolling and hopping motion on a supporting surface, the switching behaviour of azobenzene derivatives by using the STM tip and the controlled reactivity of molecular side groups, which enable the formation of covalently bound molecular nanoarchitectures. (topical review)

  20. Ion exchange/adsorbent pilot plant

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    A decontamination of greater than 99% of the actinides and fission products contained in radioactive waste water can be obtained using ion exchange resins. A system for achieving this result is described in this paper. This ion exchange pilot-plant design is the culmination of five years of study of the decontamination of radioactive waste streams by ion exchange resins and other adsorbents at Mound. In order to maintain maximum flexibility of treatments, this pilot-plant design is a conceptual design with specific flows, resins, and column specifications, but with many optional features and no rigid equipment specifications. This flexibility allows the system to be amenable to almost any radioactive waste stream. Very specific designs can be constructed from this conceptual design for the treatment of any specific waste stream. Operating and capital costs are also discussed. 1 figure, 5 tables

  1. Canyon solvent cleaning with solid adsorbents

    International Nuclear Information System (INIS)

    Reif, D.J.

    1987-01-01

    The HM Process at the Savannah River Plant (SRP) uses 7.5% tributyl phosphate in n-paraffin as an extraction solvent. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials that influence product losses, product decontamination, and separation efficiencies. Laboratory studies to improve online solvent cleaning have shown that carbonate washing, although removing residual solvent activity, does not remove binding ligands that hold fission products in the solvent. Treatment of solvent with a solid adsorbent removes binding ligands and significantly improves recycle solvent performance. Both laboratory work defining a full-scale adsorption process and the use of the process to clean HM Process first cycle solvent are presented

  2. Arsenic Remediation by Synthetic and Natural Adsorbents

    Directory of Open Access Journals (Sweden)

    Muhammad Saqaf Jagirani

    2017-06-01

    Full Text Available The contagion of toxic metals in water is a serious environmental and health concern and threatening problem worldwide. Particularly arsenic contamination in ground water has became great dilemma in the earlier decades. With advent in research for arsenic remediation, standard of drinking water is improving and now reduced to few parts per million (ppm level of arsenic in drinking water sources. However, due to continuous enhancement in environmental pollution, remediation techniques are still needed to achieve the drinking water quality standard. Development of novel and economically feasible removal techniques or materials for selective separation of this toxic specie has been the main focus of research. Several arsenic removal techniques, including membrane separation, coagulation, precipitation, anion exchange have been developed. The aim of this article is to review briefly arsenic chemistry and previous and current available technologies that have been reported various low-cost adsorbents for arsenic removal.

  3. Applications of core level spectroscopy to adsorbates

    International Nuclear Information System (INIS)

    Nilsson, Anders

    2002-01-01

    In the following review different applications of core-level spectroscopy to atomic and molecular adsorbates will be shown. Core-holes are created through core-level ionization and X-ray absorption processes and the core-hole decays by radiant and non-radiant processes. This forms the basis for X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, Auger electron spectroscopy and X-ray emission spectroscopy. We will demonstrate how we can use the different methods to obtain information about the chemical state, local geometric structure, nature of chemical bonding and dynamics in electron transfer processes. The adsorption of N 2 and CO on Ni(100) will be used as prototype systems for chemisorption while N 2 on graphite and Ar on Pt for physisorption

  4. In vitro hydroxyapatite adsorbed salivary proteins

    International Nuclear Information System (INIS)

    Vitorino, Rui; Lobo, Maria Joao C.; Duarte, Jose; Ferrer-Correia, Antonio J.; Tomer, Kenneth B.; Dubin, Joshua R.; Domingues, Pedro M.; Amado, Francisco M.L.

    2004-01-01

    In spite of the present knowledge about saliva components and their respective functions, the mechanism(s) of pellicle and dental plaque formation have hitherto remained obscure. This has prompted recent efforts on in vitro studies using hydroxyapatite (HA) as an enamel model. In the present study salivary proteins adsorbed to HA were extracted with TFA and EDTA and resolved by 2D electrophoresis over a pH range between 3 and 10, digested, and then analysed by MALDI-TOF/TOF mass spectrometry and tandem mass spectrometry. Nineteen different proteins were identified using automated MS and MS/MS data acquisition. Among them, cystatins, amylase, carbonic anhydrase, and calgranulin B, were identified

  5. Biodegradation of bacterial polysaccharides adsorbed on montmorillonite

    International Nuclear Information System (INIS)

    Guckert, A.; Tok, H.H.; Jacquin, F.

    1977-01-01

    In this research, by means of a model, a study was made of the biodegradation of microbial organic compounds adsorbed on clays, with a parallel experiment on Fontainebleau sand serving as the control. During incubation the three classes of organic matter ( 14 C-labelled glucose, 14 C-labelled polysaccharides and 14 C-labelled microbial cells) mineralize more actively in the presence of sand than in the presence of clay, since the latter provides protection against biodegradation. Mineralization of the adsorbed organic compounds, however, is marked by clear-cut differences after three weeks - glucose (55%)>polysaccharides (43%)>microbial organisms (7.3%). After incubation, chemical extraction of the organo-mineral complexes by alkaline solvents shows only water-soluble and alkali-soluble products in the case of sand; conversely, in that of montmorillonite the bulk of the 14 C was found in the non-extractable fraction or humin (18.1% of the initial 14 C for glucose, 27.3% for the polysaccharides, and 67.6% for the microbial organisms). A second incubation carried out after a phase in which there was drying and remoistening of the organo-mineral complexes, brings to light the important part played by climatic alternations during the biodegradation process. A new mineralization phase is observed, affecting more the bacterial organisms (14.1%) than the polysaccharides (6.3%), with the glucose-base complexes occupying an intermediate position (11.2%). The chemical fractioning of the organo-mineral complexes following re-incubation shows the stability of 14 C in humin very clearly, especially in the case of polysaccharides, where the mineralization phase relates primarily to the products extractable with alkalis. (author)

  6. Pulse radiolysis study of reaction of bull serum albumin electron adduct with oxygen. Polychromatic kinetics of reaction with adsorbed oxygen

    International Nuclear Information System (INIS)

    Pribush, A.G.

    1986-01-01

    By the method of pulse radiolysis the reaction of bull serum albumin electron adduct with oxygen is investigated. As pulsed radiation source electron linear accelerators with particle energy of 8.0 and 4.5 MeV and pulse time of 40 ns and 2.2 μs, respectively have been used. It is assumed that the disappearance of protein electron adduct occurs in the course of its interaction with oxygen adsorbed on protein globular molecule

  7. Understanding Trends in Catalytic Activity: The Effect of Adsorbate-Adsorbate Interactions for CO Oxidation Over Transition Metals

    DEFF Research Database (Denmark)

    Grabow, Lars; Larsen, Britt Hvolbæk; Nørskov, Jens Kehlet

    2010-01-01

    Using high temperature CO oxidation as the example, trends in the reactivity of transition metals are discussed on the basis of density functional theory (DFT) calculations. Volcano type relations between the catalytic rate and adsorption energies of important intermediates are introduced...... and the effect of adsorbate-adsorbate interaction on the trends is discussed. We find that adsorbate-adsorbate interactions significantly increase the activity of strong binding metals (left side of the volcano) but the interactions do not change the relative activity of different metals and have a very small...... influence on the position of the top of the volcano, that is, on which metal is the best catalyst....

  8. The environmental effect on the radial breathing mode of carbon nanotubes. II. Shell model approximation for internally and externally adsorbed fluids

    Science.gov (United States)

    Longhurst, M. J.; Quirke, N.

    2006-11-01

    We have previously shown that the upshift in the radial breathing mode (RBM) of closed (or infinite) carbon nanotubes in solution is almost entirely due to coupling of the RBM with an adsorbed layer of fluid on the nanotube surface. The upshift can be modeled analytically by considering the adsorbed fluid as an infinitesimally thin shell, which interacts with the nanotube via a continuum Lennard-Jones potential. Here we extend the model to include internally as well as externally adsorbed waterlike molecules, and find that filling the nanotubes leads to an additional upshift of two to six wave numbers. We show that using molecular dynamics, the RBM can be accurately reproduced by replacing the fluid molecules with a mean field harmonic shell potential, greatly reducing simulation times.

  9. 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

  10. 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.

  11. 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.

  12. 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)

  13. 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)

  14. 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)

  15. 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.

  16. 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.

  17. 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.

  18. Mass and Force Sensing of an Adsorbate on a Beam Resonator Sensor

    Directory of Open Access Journals (Sweden)

    Yin Zhang

    2015-06-01

    Full Text Available The mass sensing superiority of a micro-/nano-mechanical resonator sensor over conventional mass spectrometry has been, or at least is being firmly established. Because the sensing mechanism of a mechanical resonator sensor is the shifts of resonant frequencies, how to link the shifts of resonant frequencies with the material properties of an analyte formulates an inverse problem. Besides the analyte/adsorbate mass, many other factors, such as position and axial force, can also cause the shifts of resonant frequencies. The in situ measurement of the adsorbate position and axial force is extremely difficult if not impossible, especially when an adsorbate is as small as a molecule or an atom. Extra instruments are also required. In this study, an inverse problem of using three resonant frequencies to determine the mass, position and axial force is formulated and solved. The accuracy of the inverse problem solving method is demonstrated, and how the method can be used in the real application of a nanomechanical resonator is also discussed. Solving the inverse problem is helpful to the development and application of a mechanical resonator sensor for two reasons: reducing extra experimental equipment and achieving better mass sensing by considering more factors.

  19. Accelerator Analysis of Tributyltin Adsorbed onto the Surface of a Tributyltin Resistant Marine Pseudoalteromonas sp. Cell

    Directory of Open Access Journals (Sweden)

    Akira Kitamura

    2008-10-01

    Full Text Available Tributyltin (TBT released into seawater from ship hulls is a stable marine pollutant and obviously remains in marine environments. We isolated a TBT resistant marine Pseudoalteromonas sp. TBT1 from sediment of a ship’s ballast water. The isolate (109.3 ± 0.2 colony-forming units mL-1 adsorbed TBT in proportion to the concentrations of TBTCl externally added up to 3 mM, where the number of TBT adsorbed by a single cell was estimated to be 108.2. The value was reduced to about one-fifth when the lysozyme-treated cells were used. The surface of ethanol treated cells became rough, but the capacity of TBT adsorption was the same as that for native cells. These results indicate that the function of the cell surface, rather than that structure, plays an important role to the adsorption of TBT. The adsorption state of TBT seems to be multi-layer when the number of more than 106.8 TBT molecules is adsorbed by a single cell.

  20. Development of a computationally-designed polymeric adsorbent specific for mycotoxin patulin.

    Science.gov (United States)

    Piletska, Elena V; Pink, Demi; Karim, Kal; Piletsky, Sergey A

    2017-12-04

    Patulin is a toxic compound which is found predominantly in apples affected by mould rot. Since apples and apple-containing products are a popular food for the elderly, children and babies, the monitoring of the toxin is crucial. This paper describes a development of a computationally-designed polymeric adsorbent for the solid-phase extraction of patulin, which provides an effective clean-up of the food samples and allows the detection and accurate quantification of patulin levels present in apple juice using conventional chromatography methods. The developed bespoke polymer demonstrates a quantitative binding towards the patulin present in undiluted apple juice. The polymer is inexpensive and easy to mass-produce. The contributing factors to the function of the adsorbent is a combination of acidic and basic functional monomers producing a zwitterionic complex in the solution that formed stronger binding complexes with the patulin molecule. The protocols described in this paper provide a blueprint for the development of polymeric adsorbents for other toxins or different food matrices.

  1. A Novel Nanohybrid Nanofibrous Adsorbent for Water Purification from Dye Pollutants.

    Science.gov (United States)

    Homaeigohar, Shahin; Zillohu, Ahnaf Usman; Abdelaziz, Ramzy; Hedayati, Mehdi Keshavarz; Elbahri, Mady

    2016-10-19

    In this study, we devised a novel nanofibrous adsorbent made of polyethersulfone (PES) for removal of methylene blue (MB) dye pollutant from water. The polymer shows a low isoelectric point thus at elevated pHs and, being nanofibrous, can offer a huge highly hydroxylated surface area for adsorption of cationic MB molecules. As an extra challenge, to augment the adsorbent's properties in terms of adsorption capacity in neutral and acidic conditions and thermal stability, vanadium pentoxide (V₂O₅) nanoparticles were added to the nanofibers. Adsorption data were analyzed according to the Freundlich adsorption model. The thermodynamic parameters verified that only at basic pH is the adsorption spontaneous and in general the process is entropy-driven and endothermic. The kinetics of the adsorption process was evaluated by the pseudo-first- and pseudo-second-order models. The latter model exhibited the highest correlation with data. In sum, the adsorbent showed a promising potential for dye removal from industrial dyeing wastewater systems, especially when envisaging their alkaline and hot conditions.

  2. Motion of Adsorbed Nano-Particles on Azobenzene Containing Polymer Films

    Directory of Open Access Journals (Sweden)

    Sarah Loebner

    2016-12-01

    Full Text Available We demonstrate in situ recorded motion of nano-objects adsorbed on a photosensitive polymer film. The motion is induced by a mass transport of the underlying photoresponsive polymer material occurring during irradiation with interference pattern. The polymer film contains azobenzene molecules that undergo reversible photoisomerization reaction from trans- to cis-conformation. Through a multi-scale chain of physico-chemical processes, this finally results in the macro-deformations of the film due to the changing elastic properties of polymer. The topographical deformation of the polymer surface is sensitive to a local distribution of the electrical field vector that allows for the generation of dynamic changes in the surface topography during irradiation with different light interference patterns. Polymer film deformation together with the motion of the adsorbed nano-particles are recorded using a homemade set-up combining an optical part for the generation of interference patterns and an atomic force microscope for acquiring the surface deformation. The particles undergo either translational or rotational motion. The direction of particle motion is towards the topography minima and opposite to the mass transport within the polymer film. The ability to relocate particles by photo-induced dynamic topography fluctuation offers a way for a non-contact simultaneous manipulation of a large number of adsorbed particles just in air at ambient conditions.

  3. Vibrations of a molecule in an external force field.

    Science.gov (United States)

    Okabayashi, Norio; Peronio, Angelo; Paulsson, Magnus; Arai, Toyoko; Giessibl, Franz J

    2018-05-01

    The oscillation frequencies of a molecule on a surface are determined by the mass distribution in the molecule and the restoring forces that occur when the molecule bends. The restoring force originates from the atomic-scale interaction within the molecule and with the surface, which plays an essential role in the dynamics and reactivity of the molecule. In 1998, a combination of scanning tunneling microscopy with inelastic tunneling spectroscopy revealed the vibrational frequencies of single molecules adsorbed on a surface. However, the probe tip itself exerts forces on the molecule, changing its oscillation frequencies. Here, we combine atomic force microscopy with inelastic tunneling spectroscopy and measure the influence of the forces exerted by the tip on the lateral vibrational modes of a carbon monoxide molecule on a copper surface. Comparing the experimental data to a mechanical model of the vibrating molecule shows that the bonds within the molecule and with the surface are weakened by the proximity of the tip. This combination of techniques can be applied to analyze complex molecular vibrations and the mechanics of forming and loosening chemical bonds, as well as to study the mechanics of bond breaking in chemical reactions and atomic manipulation.

  4. 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.

  5. 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.

  6. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. 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

  9. 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.

  10. An in situ XPS study of L-cysteine co-adsorbed with water on polycrystalline copper and gold

    Science.gov (United States)

    Jürgensen, Astrid; Raschke, Hannes; Esser, Norbert; Hergenröder, Roland

    2018-03-01

    The interactions of biomolecules with metal surfaces are important because an adsorbed layer of such molecules introduces complex reactive functionality to the substrate. However, studying these interactions is challenging: they usually take place in an aqueous environment, and the structure of the first few monolayers on the surface is of particular interest, as these layers determine most interfacial properties. Ideally, this requires surface sensitive analysis methods that are operated under ambient conditions, for example ambient pressure x-ray photoelectron spectroscopy (AP-XPS). This paper focuses on an AP-XPS study of the interaction of water vapour and l-Cysteine on polycrystalline copper and gold surfaces. Thin films of l-Cysteine were characterized with XPS in UHV and in a water vapour atmosphere (P ≤ 1 mbar): the structure of the adsorbed l-Cysteine layer depended on substrate material and deposition method, and exposure of the surface to water vapour led to the formation of hydrogen bonds between H2O molecules and the COO- and NH2 groups of adsorbed l-Cysteine zwitterions and neutral molecules, respectively. This study also proved that it is possible to investigate monolayers of biomolecules in a gas atmosphere with AP-XPS using a conventional laboratory Al-Kα x-ray source.

  11. Pulse radiolysis investigation of the reaction of the electronic adduct of bovine serum albumin with oxygen. Polychromatic kinetics of the reaction with adsorbed oxygen

    International Nuclear Information System (INIS)

    Pribush, A.G.

    1986-01-01

    The method of pulse radiolysis was used to investigate the reaction of the electronic adduct of bovine serum albumin with oxygen. It was suggested that the disappearance of the electronic adduct of the protein occurs in the course of its interaction with oxygen adsorbed on the globular protein molecule

  12. High-resolution ellipsometric study of an n-alkane film, dotriacontane, adsorbed on a SiO2 surface

    DEFF Research Database (Denmark)

    Volkmann, U.G.; Pino, M.; Altamirano, L.A.

    2002-01-01

    -crystal substrates. Our results suggest a model of a solid dotriacontane film that has a phase closest to the SiO2 surface in which the long-axis of the molecules is oriented parallel to the interface. Above this "parallel film" phase, a solid monolayer adsorbs in which the molecules are oriented perpendicular...... at higher coverages. In addition, we have performed high-resolution ellipsometry and stray-light measurements on dotriacontane films deposited from solution onto highly oriented pyrolytic graphite substrates. After film deposition, these substrates proved to be less stable in air than SiO2....

  13. The Condensation of Water on Adsorbed Viruses

    NARCIS (Netherlands)

    Alonso Carnicero, J.M.; Tatti, F.; Chuvilin, A.; Mam, K.; Ondarcuhu, T.; Bittner, A.M.

    2013-01-01

    The wetting and dewetting behavior of biological nanostructures and to a greater degree single molecules is not well-known even though their contact with water is the basis for all biology. Here, we show that environmental electron microscopy (EM) can be applied as a means of imaging the

  14. 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)

  15. 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....

  16. 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.

  17. 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.

  18. Tuning the electronic structure of graphene through alkali metal and halogen atom intercalation

    Science.gov (United States)

    Ahmad, Sohail; Miró, Pere; Audiffred, Martha; Heine, Thomas

    2018-04-01

    The deposition, intercalation and co-intercalation of heavy alkali metals and light halogens atoms in graphene mono- and bilayers have been studied using first principles density-functional calculations. Both the deposition and the intercalation of alkali metals gives rise to n-type doping due to the formation of M+-C- pairs. The co-intercalation of a 1:1 ratio of alkali metals and halogens derives into the formation of ionic pairs among the intercalated species, unaltering the electronic structure of the layered material.

  19. A nuclear standard high-efficiency adsorber for iodine

    International Nuclear Information System (INIS)

    Wang Jianmin; Qian Yinge

    1988-08-01

    The structure of a nuclear standard high-efficiency adsorber, adsorbent and its performance are introduced. The performance and structure were compared with the same kind product of other firms. The results show that the leakage rate is less than 0.005%

  20. Comparative evaluation of selected starches as adsorbent for Thin ...

    African Journals Online (AJOL)

    The most commonly used is silica gel which is an inorganic adsorbent. Organic substances like cellulose, polyethylene are also used. All these are imported into Nigeria and are unhealthy for economic policies. Most commonly used adsorbent may not be easy to produce locally, but starch, which is a very common product, ...

  1. Synthesis and properties of porous zeolite aluminosilicate adsorbents

    International Nuclear Information System (INIS)

    Shilina, A.S.; Milinchuk, V.K.; Burukhin, S.B.; Gordienko, A.B.

    2015-01-01

    Environmentally safe non-energy-intensive methods of the synthesis have been developed and the properties of solid inorganic nanostructured zeolite-like adsorbents of a broad spectrum have been studied. The sorption capacities of the adsorbents with respect to various components of water pollution have been determined [ru

  2. Development of ultrafiltration and inorganic adsorbents: January--March 1977

    International Nuclear Information System (INIS)

    Koenst, J.W. Jr.

    1977-01-01

    Ultrafiltration media with and without the assistance of bone char filters were evaluated to determine their effectiveness in removing radionuclides from contaminated solutions. Precipitants, resin, adsorbents, and inorganic adsorbents were studied to determine their effectiveness in decontaminating solutions. A study of the effects of radiation on ultrafiltration media was initiated. An ultrafiltration media pilot plant was ordered and is being installed

  3. Mixed-matrix membrane adsorbers for protein separation

    NARCIS (Netherlands)

    Avramescu, M.E.; Borneman, Z.; Wessling, M.

    2003-01-01

    The separation of two similarly sized proteins, bovine serum albumin (BSA) and bovine hemoglobin (Hb) was carried out using a new type of ion-exchange mixed-matrix adsorber membranes. The adsorber membranes were prepared by incorporation of various types of Lewatit ion-exchange resins into an

  4. Single bank NOx adsorber for heavy duty diesel engines

    NARCIS (Netherlands)

    Genderen, M. van; Aken, M.G. van

    2003-01-01

    In a NOx adsorber programme the feasibility for applying this technology to heavy duty diesel engines was investigated. After modelling and simulations for realising best λ < 1 engine conditions a platform was build which was used to obtain good NOx adsorber regeneration settings in a number of

  5. 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)

  6. 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.

  7. 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...

  8. 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...

  9. 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

  10. Halogenated flame retardants in the Great Lakes environment.

    Science.gov (United States)

    Venier, Marta; Salamova, Amina; Hites, Ronald A

    2015-07-21

    Flame retardants are widely used industrial chemicals that are added to polymers, such as polyurethane foam, to prevent them from rapidly burning if exposed to a small flame or a smoldering cigarette. Flame retardants, especially brominated flame retardants, are added to many polymeric products at percent levels and are present in most upholstered furniture and mattresses. Most of these chemicals are so-called "additive" flame retardants and are not chemically bound to the polymer; thus, they migrate from the polymeric materials into the environment and into people. As a result, some of these chemicals have become widespread pollutants, which is a concern given their possible adverse health effects. Perhaps because of their environmental ubiquity, the most heavily used group of brominated flame retardants, the polybrominated diphenyl ethers (PBDEs), was withdrawn from production and use during the 2004-2013 period. This led to an increasing demand for other flame retardants, including other brominated aromatics and organophosphate esters. Although little is known about the use or production volumes of these newer flame retardants, it is evident that some of these chemicals are also becoming pervasive in the environment and in humans. In this Account, we describe our research on the occurrence of halogenated and organophosphate flame retardants in the environment, with a specific focus on the Great Lakes region. This Account starts with a short introduction to the first generation of brominated flame retardants, the polybrominated biphenyls, and then presents our measurements of their replacement, the PBDEs. We summarize our data on PBDE levels in babies, bald eagles, and in air. Once these compounds came off the market, we began to measure several of the newer flame retardants in air collected on the shores of the Great Lakes once every 12 days. These new measurements focus on a tetrabrominated benzoate, a tetrabrominated phthalate, a hexabrominated diphenoxyethane

  11. A molecular dynamics study on the transport of a charged biomolecule in a polymeric adsorbent medium and its adsorption onto a charged ligand.

    Science.gov (United States)

    Riccardi, E; Wang, J-C; Liapis, A I

    2010-08-28

    The transport of a charged adsorbate biomolecule in a porous polymeric adsorbent medium and its adsorption onto the covalently immobilized ligands have been modeled and investigated using molecular dynamics modeling and simulations as the third part of a novel fundamental methodology developed for studying ion-exchange chromatography based bioseparations. To overcome computational challenges, a novel simulation approach is devised where appropriate atomistic and coarse grain models are employed simultaneously and the transport of the adsorbate is characterized through a number of locations representative of the progress of the transport process. The adsorbate biomolecule for the system studied in this work changes shape, orientation, and lateral position in order to proceed toward the site where adsorption occurs and exhibits decreased mass transport coefficients as it approaches closer to the immobilized ligand. Furthermore, because the ligands are surrounded by counterions carrying the same type of charge as the adsorbate biomolecule, it takes the biomolecule repeated attempts to approach toward a ligand in order to displace the counterions in the proximity of the ligand and to finally become adsorbed. The formed adsorbate-ligand complex interacts with the counterions and polymeric molecules and is found to evolve slowly and continuously from one-site (monovalent) interaction to multisite (multivalent) interactions. Such a transition of the nature of adsorption reduces the overall adsorption capacity of the ligands in the adsorbent medium and results in a type of surface exclusion effect. Also, the adsorption of the biomolecule also presents certain volume exclusion effects by not only directly reducing the pore volume and the availability of the ligands in the adjacent regions, but also causing the polymeric molecules to change to more compact structures that could further shield certain ligands from being accessible to subsequent adsorbate molecules. These

  12. Ionogenic adsorbents based on local raw materials for radiation protection

    International Nuclear Information System (INIS)

    Isobaev, M.D.; Davlatnazarova, M.; Turdialiev, M.Z.; Abdullayev, T.H.; Pulatov, E.H.

    2012-01-01

    The successful management of uranium wastes and creating the conditions for effective rehabilitation activities require special adsorbents capable of holding on the surface complexes, including radioactive elements. Currently tested and have shown promising synthetic adsorbents based pitted apricot fruits and other fruit plants. This report presents data for the establishment of ionic type available adsorbents based on Tajikistan coal. As the base for the creation of this type of adsorbent were taken the coal of the 'Ziddi' deposits. As follows from our data on the chemical composition, the studied coals contain more than 20% of the ash. According to the available literature theses ashes contains various minerals compositions that can form the adsorbent's active surface. Thus, the model for this type of activated carbon can serve as a mixture of zeolite, ion exchange resins and activated carbon itself.

  13. Processing method and device for iodine adsorbing material

    International Nuclear Information System (INIS)

    Watanabe, Shin-ichi; Shiga, Reiko.

    1997-01-01

    An iodine adsorbing material adsorbing silver compounds is reacted with a reducing gas, so that the silver compounds are converted to metal silver and stored. Then, the silver compounds are not melted or recrystallized even under a highly humid condition, accordingly, peeling of the adsorbed materials from a carrier can be prevented, and the iodine adsorbing material can be stored stably. Since the device is disposed in an off gas line for discharging off gases from a nuclear power facility, the iodine adsorbing material formed by depositing silver halides to the carrier is contained, and a reducing or oxidizing gas is supplied to the vessel as required, and silver halides can be converted to metal silver or the metal silver can be returned to silver halide. (T.M.)

  14. Nano-sized Adsorbate Structure Formation in Anisotropic Multilayer System

    Science.gov (United States)

    Kharchenko, Vasyl O.; Kharchenko, Dmitrii O.; Yanovsky, Vladimir V.

    2017-05-01

    In this article, we study dynamics of adsorbate island formation in a model plasma-condensate system numerically. We derive the generalized reaction-diffusion model for adsorptive multilayer system by taking into account anisotropy in transfer of adatoms between neighbor layers induced by electric field. It will be found that with an increase in the electric field strength, a structural transformation from nano-holes inside adsorbate matrix toward separated nano-sized adsorbate islands on a substrate is realized. Dynamics of adsorbate island sizes and corresponding distributions are analyzed in detail. This study provides an insight into details of self-organization of adatoms into nano-sized adsorbate islands in anisotropic multilayer plasma-condensate systems.

  15. Noble gas separation with the use of inorganic adsorbents

    International Nuclear Information System (INIS)

    Pence, D.T.; Chou, C.C.; Christian, J.D.; Paplawsky, W.J.

    1979-01-01

    A noble gas separation process is proposed for application to airborne nuclear fuel reprocessing plant effluents. The process involves the use of inorganic adsorbents for the removal of contaminant gases and noble gas separation through selective adsorption. Water and carbon dioxide are removed with selected zeolites that do not appreciably adsorb the noble gases. Xenon is essentially quantitatively removed with a specially developed adsorbent using conventional adsorption-desorption techniques. Oxygen is removed to low ppM levels by the use of a rapid cycle adsorption technique on a special adsorbent leaving a krypton-nitrogen mixture. Krypton is separated from nitrogen with a special adsorbent operated at about -80 0 C. Because the separation process does not require high pressures and oxygen is readily removed to sufficiently limit ozone formation to insignificant levels, appreciable capital and operating cost savings with this process are possible compared with other proposed processes. In addition, the proposed process is safer to operate

  16. Flow boundary conditions for chain-end adsorbing polymer blends.

    Science.gov (United States)

    Zhou, Xin; Andrienko, Denis; Delle Site, Luigi; Kremer, Kurt

    2005-09-08

    Using the phenol-terminated polycarbonate blend as an example, we demonstrate that the hydrodynamic boundary conditions for a flow of an adsorbing polymer melt are extremely sensitive to the structure of the epitaxial layer. Under shear, the adsorbed parts (chain ends) of the polymer melt move along the equipotential lines of the surface potential whereas the adsorbed additives serve as the surface defects. In response to the increase of the number of the adsorbed additives the surface layer becomes thinner and solidifies. This results in a gradual transition from the slip to the no-slip boundary condition for the melt flow, with a nonmonotonic dependence of the slip length on the surface concentration of the adsorbed ends.

  17. Influence of Adsorbed Water on the Oxygen Evolution Reaction on Oxides

    DEFF Research Database (Denmark)

    Siahrostami, Samira; Vojvodic, Aleksandra

    2015-01-01

    We study the interface between adsorbed water and stoichiometric, defect-free (110) rutile oxide surfaces of TiO2, RuO2, and IrO2 in order to understand how water influences the stabilities of the intermediates of the oxygen evolution reaction (OER). In our model the water is treated as explicitly...... molecules binding to bridging oxygens. The third chain interacts weakly and predominantly with the H2O molecules of the second layer, resembling bulk water. We find that the stability of the water layer close to the oxide surface is almost the same as the one found on flat metal surfaces, such as the Pt(111...... of RuO2 and IrO2, while it is increased by similar to 0.4 eV for TiO2....

  18. Surface Chirality of Gly-Pro Dipeptide Adsorbed on a Cu(110) Surface.

    Science.gov (United States)

    Cruguel, Hervé; Méthivier, Christophe; Pradier, Claire-Marie; Humblot, Vincent

    2015-07-01

    The adsorption of chiral Gly-Pro dipeptide on Cu(110) has been characterized by combining in situ polarization modulation infrared reflection absorption spectroscopy (PM-RAIRS) and X-ray photoelectron spectroscopy (XPS). The chemical state of the dipeptide, and its anchoring points and adsorption geometry, were determined at various coverage values. Gly-Pro molecules are present on Cu(110) in their anionic form (NH2 /COO(-)) and adsorb under a 3-point binding via both oxygen atoms of the carboxylate group and via the nitrogen atom of the amine group. Low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) have shown the presence of an extended 2D chiral array, sustained via intermolecular H-bonds interactions. Furthermore, due to the particular shape of the molecule, only one homochiral domain is formed, creating thus a truly chiral surface. © 2015 Wiley Periodicals, Inc.

  19. Theoretical investigation on the molecular structure, Infrared, Raman and NMR spectra of para-halogen benzenesulfonamides, 4-X-C 6H 4SO 2NH 2 (X = Cl, Br or F)

    Science.gov (United States)

    Karabacak, Mehmet; Çınar, Mehmet; Çoruh, Ali; Kurt, Mustafa

    2009-02-01

    In the present study, the structural properties of para-halogen benzenesulfonamides, 4-XC 6H 4SO 2NH 2 (4-chlorobenzenesulfonamide (I), 4-bromobenzenesulfonamide (II) and 4-fluorobenzenesulfonamide (III)) have been studied extensively utilizing ab initio Hartree-Fock (HF) and density functional theory (DFT) employing B3LYP exchange correlation. The vibrational frequencies were calculated and scaled values were compared with experimental values. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The effects of the halogen substituent on the characteristic benzenesulfonamides bands in the spectra are discussed. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecules were calculated using the Gauge-Invariant Atomic Orbital (GIAO) method. Finally, geometric parameters, vibrational bands and chemical shifts were compared with available experimental data of the molecules. The fully optimized geometries of the molecules were found to be consistent with the X-ray crystal structures. The observed and calculated frequencies and chemical shifts were found to be in very good agreement.

  20. 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.

  1. The growth and electronic structure of azobenzene-based functional molecules on layered crystals

    International Nuclear Information System (INIS)

    Iwicki, J; Ludwig, E; Buck, J; Kalläne, M; Kipp, L; Rossnagel, K; Köhler, F; Herges, R

    2012-01-01

    In situ ultraviolet photoelectron spectroscopy is used to study the growth of ultrathin films of azobenzene-based functional molecules (azobenzene, Disperse Orange 3 and a triazatriangulenium platform with an attached functional azo-group) on the layered metal TiTe 2 and on the layered semiconductor HfS 2 at liquid nitrogen temperatures. Effects of intermolecular interactions, of the substrate electronic structure, and of the thermal energy of the sublimated molecules on the growth process and on the adsorbate electronic structure are identified and discussed. A weak adsorbate-substrate interaction is particularly observed for the layered semiconducting substrate, holding the promise of efficient molecular photoswitching.

  2. Influence of Exchange-Correlation Functional in the Calculations of Vertical Excitation Energies of Halogenated Copper Phthalocyanines using Time-Dependent Density Functional Theory (TD-DFT)

    International Nuclear Information System (INIS)

    Lee, Sang Uck

    2013-01-01

    The accurate prediction of vertical excitation energies is very important for the development of new materials in the dye and pigment industry. A time-dependent density functional theory (TD-DFT) approach coupled with 22 different exchange-correlation functionals was used for the prediction of vertical excitation energies in the halogenated copper phthalocyanine molecules in order to find the most appropriate functional and to determine the accuracy of the prediction of the absorption wavelength and observed spectral shifts. Among the tested functional, B3LYP functional provides much more accurate vertical excitation energies and UV-vis spectra. Our results clearly provide a benchmark calibration of the TD-DFT method for phthalocyanine based dyes and pigments used in industry

  3. Bioavailability of Carbon Nanomaterial-Adsorbed Polycyclic Aromatic Hydrocarbons to Pimphales promelas: Influence of Adsorbate Molecular Size and Configuration.

    Science.gov (United States)

    Linard, Erica N; Apul, Onur G; Karanfil, Tanju; van den Hurk, Peter; Klaine, Stephen J

    2017-08-15

    Despite carbon nanomaterials' (CNMs) potential to alter the bioavailability of adsorbed contaminants, information characterizing the relationship between adsorption behavior and bioavailability of CNM-adsorbed contaminants is still limited. To investigate the influence of CNM morphology and organic contaminant (OC) physicochemical properties on this relationship, adsorption isotherms were generated for a suite of polycyclic aromatic hydrocarbons (PAHs) on multiwalled carbon nanotubes (MWCNTs) and exfoliated graphene (GN) in conjunction with determining the bioavailability of the adsorbed PAHs to Pimphales promelas using bile analysis via fluorescence spectroscopy. Although it appeared that GN adsorbed PAHs indiscriminately compared to MWCNTs, the subsequent bioavailability of GN-adsorbed PAHs was more sensitive to PAH morphology than MWCNTs. GN was effective at reducing bioavailability of linear PAHs by ∼70%, but had little impact on angular PAHs. MWCNTs were sensitive to molecular size, where bioavailability of two-ringed naphthalene was reduced by ∼80%, while bioavailability of the larger PAHs was reduced by less than 50%. Furthermore, the reduction in bioavailability of CNM-adsorbed PAHs was negatively correlated with the amount of CNM surface area covered by the adsorbed-PAHs. This study shows that the variability in bioavailability of CNM-adsorbed PAHs is largely driven by PAH size, configuration and surface area coverage.

  4. Milestone Report - Complete New Adsorbent Materials for Marine Testing to Demonstrate 4.5 g-U/kg Adsorbent

    Energy Technology Data Exchange (ETDEWEB)

    Janke, Christopher James [ORNL; Das, Sadananda [ORNL; Oyola, Yatsandra [ORNL; Mayes, Richard T. [ORNL; Saito, Tomonori [ORNL; Brown, Suree [ORNL; Gill, Gary [PNNL; Kuo, Li-Jung [PNNL; Wood, Jordana [PNNL

    2014-08-01

    This report describes work on the successful completion of Milestone M2FT-14OR03100115 (8/20/2014) entitled, “Complete new adsorbent materials for marine testing to demonstrate 4.5 g-U/kg adsorbent”. This effort is part of the Seawater Uranium Recovery Program, sponsored by the U.S. Department of Energy, Office of Nuclear Energy, and involved the development of new adsorbent materials at the Oak Ridge National Laboratory (ORNL) and marine testing at the Pacific Northwest National Laboratory (PNNL). ORNL has recently developed two new families of fiber adsorbents that have demonstrated uranium adsorption capacities greater than 4.5 g-U/kg adsorbent after marine testing at PNNL. One adsorbent was synthesized by radiation-induced graft polymerization of itaconic acid and acrylonitrile onto high surface area polyethylene fibers followed by amidoximation and base conditioning. This fiber showed a capacity of 4.6 g-U/kg adsorbent in marine testing at PNNL. The second adsorbent was prepared by atom-transfer radical polymerization of t-butyl acrylate and acrylonitrile onto halide-functionalized round fibers followed by amidoximation and base hydrolysis. This fiber demonstrated uranium adsorption capacity of 5.4 g-U/kg adsorbent in marine testing at PNNL.

  5. 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

  6. 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.

  7. 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.

  8. SERS and DFT study of p-hydroxybenzoic acid adsorbed on colloidal silver particles.

    Science.gov (United States)

    Chen, Y; Chen, S J; Li, S; Wei, J J

    2015-10-16

    In this study, normal Raman spectra of p—hydroxybenzoic acid (PHBA) powder and its surface—enhanced Raman scattering (SERS) spectra in silver colloidal solutions were measured under near infrared excitation conditions. In theoretical calculation, two models of PHBA adsorbed on the surfaces of silver nanoparticles were established. The Raman frequencies of these two models using density functional theory (DFT) method were calculated, and compared with the experimental results. It was found that the calculated Raman frequencies were in good agreement with experimental values, which indicates that there are two enhanced mechanism physical (electromagnetic, EM) enhancement and chemical (charge—transfer, CT) enhancement, in silver colloidal solutions regarding SERS effect. Furthermore, from high—quality SERS spectrum of PHBA obtained in silver colloids, we inferred that PHBA molecules in silver colloids adsorb onto the metal surfaces through carboxyl at a perpendicular orientation. The combination of SERS spectra and DFT calculation is thus useful for studies of the adsorption—orientation of a molecule on a metal colloid.

  9. The Tunable Bandgap of AB-Stacked Bilayer Graphene on SiO2 with H2O Molecule Adsorption

    International Nuclear Information System (INIS)

    Wang Tao; Guo Qing; Liu Yan; Wang Wen-Bo; Sheng Kuang; Ao Zhi-Min; Yu Bin

    2011-01-01

    The atomic and electronic structures of AB-stacking bilayer graphene (BLG) in the presence of H 2 O molecules are investigated by density functional theory calculations. For free-standing BLG, the bandgap is opened to 0.101 eV with a single H 2 O molecule adsorbed on its surface. The perfectly suspended BLG is sensitive to H 2 O adsorbates, which break the BLG lattice symmetry and open an energy gap. While a single H 2 O molecule is adsorbed on the BLG surface with a SiO 2 substrate, the bandgap widens to 0.363 eV. Both the H 2 O molecule adsorption and the oxide substrate contribute to the BLG bandgap opening. The phenomenon is interpreted with the charge transfer process in 2D carbon nanostructures. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  10. Surface characterization of Ag/Titania adsorbents

    International Nuclear Information System (INIS)

    Samokhvalov, Alexander; Nair, Sachin; Duin, Evert C.; Tatarchuk, Bruce J.

    2010-01-01

    The Ag/Titania adsorbent for selective removal of the desulfurization-refractive polycyclic aromatic sulfur heterocycles (PASHs) from liquid hydrocarbon fuels was prepared, its total and the Ag specific surface area were determined and the surface reaction sites in the sorbent that may be active in the adsorptive selective desulfurization were characterized by several spectroscopic and surface science techniques. The sorbent contains Ag, Ti, O and spurious C on its surface, as by the XPS measurements. Silver is present as an oxide, as judged by the XPS Auger parameter (AP). The complementary electron spin resonance (ESR) spectroscopy confirms that the majority of Ag is present in the diamagnetic Ag 1+ form, with the minor concentration (∼0.1% of total Ag) present as Ag 2+ . The findings by XPS and ESR are confirmed by the XRD, UV-vis spectroscopy and thermodynamic considerations. The supported Ag is highly dispersed on the surface of the titania support, with the particle size of ∼30-60 A depending on Ag content, with an Ag specific surface area of ∼7-14 m 2 /g, vs. the total surface area of ∼114-58 m 2 /g.

  11. Self-consistent field theory of polymer-ionic molecule complexation.

    Science.gov (United States)

    Nakamura, Issei; Shi, An-Chang

    2010-05-21

    A self-consistent field theory is developed for polymers that are capable of binding small ionic molecules (adsorbates). The polymer-ionic molecule association is described by Ising-like binding variables, C(i) ((a))(kDelta)(=0 or 1), whose average determines the number of adsorbed molecules, n(BI). Polymer gelation can occur through polymer-ionic molecule complexation in our model. For polymer-polymer cross-links through the ionic molecules, three types of solutions for n(BI) are obtained, depending on the equilibrium constant of single-ion binding. Spinodal lines calculated from the mean-field free energy exhibit closed-loop regions where the homogeneous phase becomes unstable. This phase instability is driven by the excluded-volume interaction due to the single occupancy of ion-binding sites on the polymers. Moreover, sol-gel transitions are examined using a critical degree of conversion. A gel phase is induced when the concentration of adsorbates is increased. At a higher concentration of the adsorbates, however, a re-entrance from a gel phase into a sol phase arises from the correlation between unoccupied and occupied ion-binding sites. The theory is applied to a model system, poly(vinyl alcohol) and borate ion in aqueous solution with sodium chloride. Good agreement between theory and experiment is obtained.

  12. 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),...

  13. 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.

  14. 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.

  15. 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....

  16. 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.

  17. 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

  18. 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

  19. 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...

  20. 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