Sample records for halogenated organic chemicals

  1. Aerosol-halogen interaction: Change of physico-chemical properties of SOA by naturally released halogen species

    NASA Astrophysics Data System (ADS)

    Ofner, J.; Balzer, N.; Buxmann, J.; Grothe, H.; Krüger, H.; Platt, U.; Schmitt-Kopplin, P.; Zetzsch, C.

    2011-12-01

    Reactive halogen species are released by various sources like photo-activated sea-salt aerosol or salt pans and salt lakes. These heterogeneous release mechanisms have been overlooked so far, although their potential of interaction with organic aerosols like Secondary Organic Aerosol (SOA), Biomass Burning Organic Aerosol (BBOA) or Atmospheric Humic LIke Substances (HULIS) is completely unknown. Such reactions can constitute sources of gaseous organo-halogen compounds or halogenated organic particles in the atmospheric boundary layer. To study the interaction of organic aerosols with reactive halogen species (RHS), SOA was produced from α-pinene, catechol and guaiacol using an aerosol smog-chamber. The model SOAs were characterized in detail using a variety of physico-chemical methods (Ofner et al., 2011). Those aerosols were exposed to molecular halogens in the presence of UV/VIS irradiation and to halogens, released from simulated natural halogen sources like salt pans, in order to study the complex aerosol-halogen interaction. The heterogeneous reaction of RHS with those model aerosols leads to different gaseous species like CO2, CO and small reactive/toxic molecules like phosgene (COCl2). Hydrogen containing groups on the aerosol particles are destroyed to form HCl or HBr, and a significant formation of C-Br bonds could be verified in the particle phase. Carbonyl containing functional groups of the aerosol are strongly affected by the halogenation process. While changes of functional groups and gaseous species were visible using FTIR spectroscopy, optical properties were studied using Diffuse Reflectance UV/VIS spectroscopy. Overall, the optical properties of the processed organic aerosols are significantly changed. While chlorine causes a "bleaching" of the aerosol particles, bromine shifts the maximum of UV/VIS absorption to the red end of the UV/VIS spectrum. Further physico-chemical changes were recognized according to the aerosol size-distributions or the

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

    PubMed

    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 (<0.1). General indices such as the 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.

  3. Likelihood of atom-atom contacts in crystal structures of halogenated organic compounds.

    PubMed

    Jelsch, Christian; Soudani, Sarra; Ben Nasr, Cherif

    2015-05-01

    The likelihood of occurrence of intermolecular contacts in crystals of halogenated organic compounds has been analysed statistically using tools based on the Hirshfeld surface. Several families of small halogenated molecules (containing organic F, Cl, Br or I atoms) were analysed, based on chemical composition and aromatic or aliphatic character. The behaviour of crystal contacts was also probed for molecules containing O or N. So-called halogen bonding (a halogen making short interactions with O or N, or a π interaction with C) is generally disfavoured, except when H is scarce on the molecular surface. Similarly, halogen⋯halogen contacts are more rare than expected, except for molecules that are poor in H. In general, the H atom is found to be the preferred partner of organic halogen atoms in crystal structures. On the other hand, C⋯C interactions in parallel π-stacking have a high propensity to occur in halogenated aromatic molecules. The behaviour of the four different halogen species (F, Cl, Br, I) is compared in several chemical composition contexts. The analysis tool can be refined by distinguishing several types for a given chemical species, such as H atoms bound to O or C. Such distinction shows, for instance, that C-H⋯Cl and O-H⋯O are the preferred interactions in compounds containing both O and Cl.

  4. Temporal dynamics of halogenated organic compounds in Marcellus Shale flowback.

    PubMed

    Luek, Jenna L; Harir, Mourad; Schmitt-Kopplin, Philippe; Mouser, Paula J; Gonsior, Michael

    2018-06-01

    The chemistry of hydraulic fracturing fluids and wastewaters is complex and is known to vary by operator, geologic formation, and fluid age. A time series of hydraulic fracturing fluids, flowback fluids, and produced waters was collected from two adjacent Marcellus Shale gas wells for organic chemical composition analyses using ultrahigh resolution mass spectrometry. Hierarchical clustering was used to compare and extract ions related to different fluid ages and many halogenated organic molecular ions were identified in flowback fluids and early produced waters based on exact mass. Iodinated organic compounds were the dominant halogen class in these clusters and were nearly undetectable in hydraulic fracturing fluid prior to injection. The iodinated ions increased in flowback and remained elevated after ten months of well production. We suggest that these trends are mainly driven by dissolved organic matter reacting with reactive halogen species formed abiotically through oxidizing chemical additives applied to the well and biotically via iodide-oxidizing bacteria. Understanding the implications of these identified halogenated organic compounds will require future investigation in to their structures and environmental fate. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Human exposures to volatile halogenated organic chemicals in indoor and outdoor air.

    PubMed Central

    Andelman, J B

    1985-01-01

    Volatile halogenated organic chemicals are found in indoor and outdoor air, often at concentrations substantially above those in remote, unpopulated areas. The outdoor ambient concentrations vary considerably among sampling stations throughout the United States, as well as diurnally and daily. The vapor pressures and air-water equilibrium (Henry's Law) constants of these chemicals influence considerably the likely relative human exposures for the air and water routes. Volatilization of chemicals from indoor uses of water can be a substantial source of exposure, as shown for radon-222. Measurements of air concentrations of trichloroethylene (TCE) in showers using TCE contaminated groundwater show increases with time to as high as one-third of occupational threshold limit values. Using a scaled down experimental shower, such volatilization and subsequent decay in air was also demonstrated. Using a simplified indoor air model and assuming complete volatilization from a full range of typical water uses within the home, calculations indicate that the expected air inhalation exposures can be substantially higher than those from ingestion of these chemicals in drinking water. Although the regulation of toxic chemicals in potable water supplies has focused traditionally on direct ingestion, the volatilization and inhalation from other much greater volume indoor uses of water should be considered as well. PMID:4085436

  6. Method for halogenating or radiohalogenating a chemical compound

    DOEpatents

    Kabalka, George W.

    2006-05-09

    A method for obtaining a halogenated organic compound, whereby an organotrifluoroborate compound is reacted with a halide ion in the presence of an oxidizing agent to produce the corresponding halogenated organic compound. The method may be used for producing radiohalogenated organic compounds.

  7. Electroreduction of Halogenated Organic Compounds

    NASA Astrophysics Data System (ADS)

    Rondinini, Sandra; Vertova, Alberto

    The electroreductive cleavage of the carbon-halogen bond in halogenated organic compounds has been extensively studied for more than 70 years, since it is prodromal to a large variety of synthetic applications in organic electrochemistry. Over the years the research interest have progressively included the environmental applications, since several organic halocompounds are known to have (or have had) a serious environmental impact because of their (present or past) wide use as cleaning agents, herbicides, cryogenic fluids, reagents (e.g. allyl and vinyl monomers) for large production materials, etc. Recent studies have also demonstrated the wide spread out- and in-door-presence of volatile organic halides, although at low level, in connexion with residential and non-residential (e.g. stores, restaurants and transportation) activities. In this context, the detoxification of emissions to air, water and land by the selective removal of the halogen group represents a valid treatment route, which, although not leading to the complete mineralization of the pollutants, produces less harmful streams to be easily treated by electrochemical or conventional techniques. The electroreduction process is analysed and discussed in terms of electrode material, reaction medium, cell design and operation, and of substrate classification.

  8. Enzymatic Halogenation and Dehalogenation Reactions: Pervasive and Mechanistically Diverse.

    PubMed

    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.

  9. Halogenated Organic Compounds Identified in Hydraulic Fracturing Wastewaters Using Ultrahigh Resolution Mass Spectrometry.

    PubMed

    Luek, Jenna L; Schmitt-Kopplin, Philippe; Mouser, Paula J; Petty, William Tyler; Richardson, Susan D; Gonsior, Michael

    2017-05-16

    Large volumes of water return to the surface following hydraulic fracturing of deep shale formations to retrieve oil and natural gas. Current understanding of the specific organic constituents in these hydraulic fracturing wastewaters is limited to hydrocarbons and a fraction of known chemical additives. In this study, we analyzed hydraulic fracturing wastewater samples using ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) as a nontargeted technique to assign unambiguous molecular formulas to singly charged molecular ions. Halogenated molecular formulas were identified and confirmed using isotopic simulation and MS-MS fragmentation spectra. The abundance of halogenated organic compounds in flowback fluids rather than older wastewaters suggested that the observed molecular ions might have been related to hydraulic fracturing additives and related subsurface reactions, such as through the reaction of shale-extracted chloride, bromide, and iodide with strong oxidant additives (e.g., hypochlorite, persulfate, hydrogen peroxide) and subsequently with diverse dissolved organic matter. Some molecular ions matched the exact masses of known disinfection byproducts including diiodoacetic acid, dibromobenzoic acid, and diiodobenzoic acid. The identified halogenated organic compounds, particularly iodinated organic molecules, are absent from inland natural systems and these compounds could therefore play an important role as environmental tracers.

  10. Halogenated volatile organic compounds from the use of chlorine-bleach-containing household products.

    PubMed

    Odabasi, Mustafa

    2008-03-01

    Sodium hypochlorite (NaOCl) and many organic chemicals contained in household cleaning products may react to generate halogenated volatile organic compounds (VOCs). Halogenated VOC emissions from eight different chlorine bleach containing household products (pure and diluted) were investigated by headspace experiments. Chloroform and carbon tetrachloride were the leading compounds along with several halogenated compounds in the headspace of chlorine bleach products. One of the most surprising results was the presence of carbon tetrachloride (a probable human carcinogen and a powerful greenhouse gas that was banned for household use by the U.S. Food and Drug Administration) in very high concentrations (up to 101 mg m(-3)). By mixing surfactants or soap with NaOCl, it was shown that the formation of carbon tetrachloride and several other halogenated VOCs is possible. In addition to quantitatively determined halogenated VOCs (n = 15), several nitrogen-containing (n = 4), chlorinated (n = 10), oxygenated compounds (n = 22), and hydrocarbons (n = 14) were identified in the headspace of bleach products. Among these, 1,1-dichlorobutane and 2-chloro-2-nitropropane were the most abundant chlorinated VOCs, whereas trichloronitromethane and hexachloroethane were the most frequently detected ones. Indoor air halogenated VOC concentrations resulting from the use of four selected household products were also measured before, during, and 30 min after bathroom, kitchen, and floor cleaning applications. Chloroform (2.9-24.6 microg m(-3)) and carbon tetrachloride (0.25-459 microg m(-3)) concentrations significantly increased during the use of bleach containing products. During/ before concentration ratios ranged between 8 and 52 (25 +/- 14, average +/- SD) for chloroform and 1-1170 (146 +/- 367, average +/- SD) for carbon tetrachloride, respectively. These results indicated that the bleach use can be important in terms of inhalation exposure to carbon tetrachloride, chloroform and

  11. Formation of halogen-induced secondary organic aerosol (XOA)

    NASA Astrophysics Data System (ADS)

    Kamilli, Katharina; Ofner, Johannes; Zetzsch, Cornelius; Held, Andreas

    2013-04-01

    Reactive halogen species (RHS) are very important due to their potential of stratospheric ozone depletion and surface ozone destruction. RHS seem to interact with precursors of secondary organic aerosol (SOA) similarly to common atmospheric oxidants like OH radicals and ozone. The potential interaction of RHS with preformed SOA has recently been studied (Ofner et al., 2012). Although aerosol formation from reaction of RHS with typical SOA precursors was previously studied (e.g. Cai et al., 2006), no data are available on bromine-induced aerosol formation from organic precursors yet. An aerosol smog-chamber was used to examine the halogen-induced secondary organic aerosol (XOA) formation under atmospheric conditions using simulated sunlight. With a concentration of 10 ppb for the organic precursor, 2 ppb for molecular chlorine, and 10 ppb for molecular bromine, the experimental setup is close to ambient conditions. By combined measurements of the aerosol size distribution, ozone and NOx mixing ratios, as well as the decay of the organic precursor, aerosol yields and aerosol growth rates were determined. The decay of the organic precursor was analyzed by capillary gas chromatography coupled with flame-ionization detection (GC-FID) and the aerosol size distribution was measured using a Scanning Mobility Particle Sizer (SMPS). Additionally, with the decay rate of the precursor and the calculated photolysis rates of molecular halogen species, based on the well-known spectrum of the solar simulator, mechanistic details on the XOA formation pathways can be determined. We observed XOA formation even at very low precursor and RHS concentrations with a diameter mode at 10-20 nm and a number concentration up to 1000000 particles cm-3. While the XOA formation from chlorine is very rapid, the interaction of bromine with the organic precursors is about five times slower. The aerosol yield reached maximum values of 0.01 for the reaction of chlorine with α-pinene and 0.0004 for

  12. 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

    NASA Astrophysics Data System (ADS)

    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.

  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.

    PubMed

    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. Graphical Abstract ᅟ.

  14. Volatile Halogenated Organic Compounds Released to Seawater from Temperate Marine Macroalgae

    NASA Astrophysics Data System (ADS)

    Gschwend, Philip M.; Macfarlane, John K.; Newman, Kathleen A.

    1985-03-01

    Volatile halogenated organic compounds synthesized by various industrial processes are troublesome pollutants because they are persistent in terrestrial ecosystems and because they may be present in sufficient quantities to alter the natural atmospheric cycles of the halogens. Certain of these compounds, including polybromomethanes and several previously unobserved alkyl monohalides and dihalides, appear to be natural products of the marine environment. A variety of temperate marine macroalgae (the brown algae Ascophyllum nodosum and Fucus vesiculosis, the green algae Enteromorpha linza and Ulva lacta, and the red alga Gigartina stellata) not only contain volatile halogenated organic compounds but also release them to seawater at rates of nanograms to micrograms of each compound per gram of dry algae per day. The macroalgae may be an important source of bromine-containing material released to the atmosphere.

  15. Chemical Action of Halogenated Agents in Fire Extinguishing

    NASA Technical Reports Server (NTRS)

    Belles, Frank E.

    1955-01-01

    The action of halogenated agents in preventing flame propagation in fuel-air mixtures in laboratory tests is discussed in terms of a possible chemical mechanism. The mechanism chosen is that of chain-breaking reactions between agent and active particles (hydrogen and oxygen atoms and hydroxyl radicsls). Data from the literature on the flammability peaks of n-heptane agent-air mixtures are treated. Ratings of agent effectiveness in terms of the fuel equivalent of the agent, based on both fuel and agent concentrations at the peak, are proposed as preferable to ratings in terms of agent concentration alone. These fuel-equivalent ratings are roughly correlated by reactivities assigned to halogen and hydrogen atoms in the agent molecules. It is concluded that the presence of hydrogen in agent need not reduce its fire-fighting ability, provided there is enough halogen to make the agent nonflammable. A method is presented for estimating from quenching-distance data a rate constant for the reaction of agent with active particles. A quantitative result is obtained for methyl bromide. This rate constant predicts the observed peak concentration of methyl bromide quite well. However, more data are needed to prove the validity of the method. The assumption that hal.ogenatedagents act mainly by chain-bresking reactions with active particles is consistent with the experimental facts and should help guide the selection of agents for further tests.

  16. Competition between Halogen, Hydrogen and Dihydrogen Bonding in Brominated Carboranes.

    PubMed

    Fanfrlík, Jindřich; Holub, Josef; Růžičková, Zdeňka; Řezáč, Jan; Lane, Paul D; Wann, Derek A; Hnyk, Drahomír; Růžička, Aleš; Hobza, Pavel

    2016-11-04

    Halogen bonds are a subset of noncovalent interactions with rapidly expanding applications in materials and medicinal chemistry. While halogen bonding is well known in organic compounds, it is new in the field of boron cluster chemistry. We have synthesized and crystallized carboranes containing Br atoms in two different positions, namely, bound to C- and B-vertices. The Br atoms bound to the C-vertices have been found to form halogen bonds in the crystal structures. In contrast, Br atoms bound to B-vertices formed hydrogen bonds. Quantum chemical calculations have revealed that halogen bonding in carboranes can be much stronger than in organic architectures. These findings open new possibilities for applications of carboranes, both in materials and medicinal chemistry. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Chemical cleaning-associated generation of dissolved organic matter and halogenated byproducts in ceramic MBR: Ozone versus hypochlorite.

    PubMed

    Sun, Huifang; Liu, Hang; Han, Jiarui; Zhang, Xiangru; Cheng, Fangqin; Liu, Yu

    2018-09-01

    This study characterized the dissolved organic matter (DOM) and byproducts generated after the exposure of activated sludge to ozone and NaClO in ceramic MBR. It was found that NaClO triggered more significant release of DOM than ozone. Proteins with the molecular weight greater than 20 kDa and humic acid like-substances were the principal components of DOM generated by NaClO, while ozone was found to effectively degrade larger biopolymers to low molecular weight substances. The results showed that more than 80% of DOM generated by NaClO and ozone could pass through the 0.2-μm ceramic membrane. Furthermore, total organic chlorine (TOCl) was determined to be the principal species of halogenated byproducts in both cases, while the generation of TOCl by NaClO was much more significant than that by ozone. Only a small fraction of TOCl was removed by the 0.2-μm ceramic membrane. More importantly, the toxic bioassays further revealed that the supernatant of sludge suspension and permeate in the MBR with NaClO cleaning exhibited higher developmental toxicity to the polychaete embryos than those by ozone. The results clearly showed that on-line chemical cleaning with ozone should be a more eco-friendly and safer approach for sustaining long-term membrane permeability in ceramic MBR. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Organic Halogen and Related Trace Gases in the Tropical Atmosphere: Results from Recent Airborne Campaigns Over the Pacific

    NASA Astrophysics Data System (ADS)

    Atlas, E. L.; Navarro, M. A.; Donets, V.; Schauffler, S.; Lueb, R.; Hendershot, R.; Gabbard, S.; Hornbrook, R. S.; Apel, E. C.; Riemer, D. D.; Pan, L.; Salawitch, R. J.; Nicely, J. M.; Montzka, S. A.; Miller, B.; Moore, F. L.; Elkins, J. W.; Hintsa, E. J.; Campos, T. L.; Quack, B.; Zhu, X.; Pope, L.

    2014-12-01

    Organic halogen gases, especially containing bromine and iodine, play a significant role as precursors to active halogen chemistry and ozone catalytic loss. Much of the reactive organic halogen originates from biological processes in the surface ocean, which can be quite variable by season and location. The tropics and coastal margins are potentially important sources that are being examined. The recent coordinated CONTRAST/ATTREX/CAST missions were conducted in the Western Tropical Pacific, a region that is a major transport pathway for tropospheric air entering the stratosphere. One of the goals of the missions was to identify sources, distributions, and transport of organic halogens from the ocean surface into the tropical lower stratosphere. The missions were conducted during the NH winter season, Jan-Feb, 2014. In this presentation, we will discuss the distributions and variability of organic halogen gases in the study region and will examine the input of organic halogen species into the Tropical Tropopause Layer (TTL). Comparison with other tracers, such as methyl nitrate and NMHC, will help identify source regions for these gases. We will focus on the measurements obtained in the CONTRAST and ATTREX missions with data from in-situ GC/MS measurements and whole air samples collected on the NSF GV and NASA Global Hawk aircraft. Comparisons with other recent airborne campaigns, such as HIPPO and TC4, and with several ship-based studies will provide an additional context for evaluating the variability of organic halogen species in the tropical atmosphere and their role in transporting reactive halogen compounds into the UT/LS.

  19. Thyroid disrupting effects of halogenated and next generation chemicals on the swim bladder development of zebrafish.

    PubMed

    Godfrey, Amy; Hooser, Blair; Abdelmoneim, Ahmed; Horzmann, Katharine A; Freemanc, Jennifer L; Sepúlveda, Maria S

    2017-12-01

    Endocrine disrupting chemicals (EDCs) can alter thyroid function and adversely affect growth and development. Halogenated compounds, such as perfluorinated chemicals commonly used in food packaging, and brominated flame retardants used in a broad range of products from clothing to electronics, can act as thyroid disruptors. Due to the adverse effects of these compounds, there is a need for the development of safer next generation chemicals. The objective of this study was to test the thyroid disruption potential of old use and next generation halogenated chemicals. Zebrafish embryos were exposed to three old use compounds, perfluorooctanoic acid (PFOA), tetrabromobisphenol A (TBBPA) and tris (1,3-dichloro-2-propyl) phosphate (TDCPP) and two next generation chemicals, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxdie (DOPO) and perfluorobutyric acid (PFBA). Sub-chronic (0-6days post fertilization (dpf)) and chronic (0-28dpf) exposures were conducted at 1% of the concentration known to kill 50% (LC 50 ) of the population. Changes in the surface area of the swim bladder as well as in expression levels of genes involved in the thyroid control of swim bladder inflation were measured. At 6dpf, zebrafish exposed to all halogenated chemicals, both old use and next generation, had smaller posterior swim bladder and increased expression in the gene encoding thyroid peroxidase, tpo and the genes encoding two swim bladder surfactant proteins, sp-a and sp-c. These results mirrored the effects of thyroid hormone-exposed positive controls. Fish exposed to a TPO inhibitor (methimazole, MMI) had a decrease in tpo expression levels at 28dpf. Effects on the anterior swim bladder at 28dpf, after exposure to MMI as well as both old and new halogenated chemicals, were the same, i.e., absence of SB in ∼50% of fish, which were also of smaller body size. Overall, our results suggest thyroid disruption by the halogenated compounds tested via the swim bladder surfactant system. However

  20. Atomic resolution ADF-STEM imaging of organic molecular crystal of halogenated copper phthalocyanine.

    PubMed

    Haruta, Mitsutaka; Yoshida, Kaname; Kurata, Hiroki; Isoda, Seiji

    2008-05-01

    Annular dark-field (ADF) scanning transmission electron microscopy (STEM) measurements are demonstrated for the first time to be applicable for acquiring Z-contrast images of organic molecules at atomic resolution. High-angle ADF imaging by STEM is a new technique that provides incoherent high-resolution Z-contrast images for organic molecules. In the present study, low-angle ADF-STEM is successfully employed to image the molecular crystal structure of hexadecachloro-Cu-phthalocyanine (Cl16-CuPc), an organic molecule. The structures of CuPc derivatives (polyhalogenated CuPc with Br and Cl) are determined quantitatively using the same technique to determine the occupancy of halogens at each chemical site. By comparing the image contrasts of atomic columns, the occupancy of Br is found to be ca. 56% at the inner position, slightly higher than that for random substitution and in good agreement with previous TEM results.

  1. Halogenation of Hydraulic Fracturing Additives in the Shale Well Parameter Space

    NASA Astrophysics Data System (ADS)

    Sumner, A. J.; Plata, D.

    2017-12-01

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

  2. A box model study on photochemical interactions between VOCs and reactive halogen species in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Toyota, K.; Kanaya, Y.; Takahashi, M.; Akimoto, H.

    2003-09-01

    A new chemical scheme is developed for the multiphase photochemical box model SEAMAC (size-SEgregated Aerosol model for Marine Air Chemistry) to investigate photochemical interactions between volatile organic compounds (VOCs) and reactive halogen species in the marine boundary layer (MBL). Based primarily on critically evaluated kinetic and photochemical rate parameters as well as a protocol for chemical mechanism development, the new scheme has achieved a near-explicit treatment of oxidative degradation of up to C3-hydrocarbons CH4, C2H6, C3H8, C2H4, C3H6, and C2H2) initiated by reactions with OH radicals, Cl- and Br-atoms, and O3. Rate constants and product yields for reactions involving halogen species are taken from the literature where available, but the majority of them need to be estimated. In particular, addition reactions of halogen atoms with alkenes will result in the formation of halogenated organic intermediates, whose photochemical loss rates are carefully evaluated in the present work. Model calculations with the new chemical scheme reveal that the oceanic emissions of acetaldehyde (CH3CHO) and alkenes (especially C3H6) are important factors for regulating reactive halogen chemistry in the MBL by promoting the conversion of Br atoms into HBr or more stable brominated intermediates in the organic form. The latter include brominated hydroperoxides, bromoacetaldehyde, and bromoacetone, which sequester bromine from reactive inorganic pool. The total mixing ratio of brominated organic species thus produced is likely to reach 10-20% or more of that of inorganic gaseous bromine species over wide regions over the ocean. On the other hand, the reaction between Br atoms and C2H2 is unimportant for determining the degree of bromine activation in the remote MBL. It is suggested that peroxyacetic acid formed via CH3CHO oxidation is one of the important chemical agents for triggering autocatalytic halogen release from sea-salt aerosols. These results imply that

  3. Environmental health sciences center task force review on halogenated organics in drinking water.

    PubMed

    Deinzer, M; Schaumburg, F; Klein, E

    1978-06-01

    The disinfection of drinking water by chlorination has in recent years come under closer scrutiny because of the potential hazards associated with the production of stable chlorinated organic chemicals. Organic chemical contaminants are common to all water supplies and it is now well-established that chlorinated by-products are obtained under conditions of disinfection, or during tertiary treatment of sewage whose products can ultimately find their way into drinking water supplies. Naturally occurring humic substances which are invariably present in drinking waters are probably the source of chloroform and other halogenated methanes, and chloroform has shown up in every water supply investigated thus far.The Environmental Protection Agency is charged with the responsibility of assessing the public health effects resulting from the consumption of contaminated drinking water. It has specifically undertaken the task of determining whether organic contaminants or their chlorinated derivatives have a special impact, and if so, what alternatives there are to protect the consumer against bacterial and viral diseases that are transmitted through infected drinking waters. The impetus to look at these chemicals is not entirely without some prima facie evidence of potential trouble. Epidemiological studies suggested a higher incidence of cancer along the lower Mississippi River where the contamination from organic chemicals is particularly high. The conclusions from these studies have, to be sure, not gone unchallenged.The task of assessing the effects of chemicals in the drinking water is a difficult one. It includes many variables, including differences in water supplies and the temporal relationship between contamination and consumption of the finished product. It must also take into account the relative importance of the effects from these chemicals in comparison to those from occupational exposure, ingestion of contaminated foods, inhalation of polluted air, and many

  4. Halogen Chemistry in the CMAQ Model

    EPA Science Inventory

    Halogens (iodine and bromine) emitted from oceans alter atmospheric chemistry and influence atmospheric ozone mixing ratio. We previously incorporated a representation of detailed halogen chemistry and emissions of organic and inorganic halogen species into the hemispheric Commun...

  5. SUBSTITUTION REACTIONS FOR THE DETOXIFICATION OF HAZARDOUS CHEMICALS

    EPA Science Inventory

    Chemical Treatment is one of several treatment techniques used for the remediation of toxic and hazardous chemicals. Chemical treatment in this report is defined as substitution of halogens by hydrogens for the conversion of halogenated organic toxicant into its native hydrocarb...

  6. A box model study on photochemical interactions between VOCs and reactive halogen species in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Toyota, K.; Kanaya, Y.; Takahashi, M.; Akimoto, H.

    2004-09-01

    A new chemical scheme is developed for the multiphase photochemical box model SEAMAC (size-SEgregated Aerosol model for Marine Air Chemistry) to investigate photochemical interactions between volatile organic compounds (VOCs) and reactive halogen species in the marine boundary layer (MBL). Based primarily on critically evaluated kinetic and photochemical rate parameters as well as a protocol for chemical mechanism development, the new scheme has achieved a near-explicit description of oxidative degradation of up to C3-hydrocarbons (CH4, C2H6, C3H8, C2H4, C3H6, and C2H2) initiated by reactions with OH radicals, Cl- and Br-atoms, and O3. Rate constants and product yields for reactions involving halogen species are taken from the literature where available, but the majority of them need to be estimated. In particular, addition reactions of halogen atoms with alkenes will result in forming halogenated organic intermediates, whose photochemical loss rates are carefully evaluated in the present work. Model calculations with the new chemical scheme reveal that the oceanic emissions of acetaldehyde (CH3CHO) and alkenes (especially C3H6) are important factors for regulating reactive halogen chemistry in the MBL by promoting the conversion of Br atoms into HBr or more stable brominated intermediates in the organic form. The latter include brominated hydroperoxides, bromoacetaldehyde, and bromoacetone, which sequester bromine from a reactive inorganic pool. The total mixing ratio of brominated organic species thus produced is likely to reach 10-20% or more of that of inorganic gaseous bromine species over wide regions over the ocean. The reaction between Br atoms and C2H2 is shown to be unimportant for determining the degree of bromine activation in the remote MBL. These results imply that reactive halogen chemistry can mediate a link between the oceanic emissions of VOCs and the behaviors of compounds that are sensitive to halogen chemistry such as dimethyl sulfide, NOx, and

  7. Impact of enhanced ozone deposition and halogen chemistry on model performance

    EPA Science Inventory

    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...

  8. Environmental health sciences center task force review on halogenated organics in drinking water

    PubMed Central

    Deinzer, M.; Schaumburg, F.; Klein, E.

    1978-01-01

    The disinfection of drinking water by chlorination has in recent years come under closer scrutiny because of the potential hazards associated with the production of stable chlorinated organic chemicals. Organic chemical contaminants are common to all water supplies and it is now well-established that chlorinated by-products are obtained under conditions of disinfection, or during tertiary treatment of sewage whose products can ultimately find their way into drinking water supplies. Naturally occurring humic substances which are invariably present in drinking waters are probably the source of chloroform and other halogenated methanes, and chloroform has shown up in every water supply investigated thus far. The Environmental Protection Agency is charged with the responsibility of assessing the public health effects resulting from the consumption of contaminated drinking water. It has specifically undertaken the task of determining whether organic contaminants or their chlorinated derivatives have a special impact, and if so, what alternatives there are to protect the consumer against bacterial and viral diseases that are transmitted through infected drinking waters. The impetus to look at these chemicals is not entirely without some prima facie evidence of potential trouble. Epidemiological studies suggested a higher incidence of cancer along the lower Mississippi River where the contamination from organic chemicals is particularly high. The conclusions from these studies have, to be sure, not gone unchallenged. The task of assessing the effects of chemicals in the drinking water is a difficult one. It includes many variables, including differences in water supplies and the temporal relationship between contamination and consumption of the finished product. It must also take into account the relative importance of the effects from these chemicals in comparison to those from occupational exposure, ingestion of contaminated foods, inhalation of polluted air, and many

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

    PubMed

    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.

  10. Room-Temperature Phosphorescence in Pure Organic Materials: Halogen Bonding Switching Effects.

    PubMed

    Xiao, Lu; Wu, Yishi; Yu, Zhenyi; Xu, Zhenzhen; Li, Jinbiao; Liu, Yanping; Yao, Jiannian; Fu, Hongbing

    2018-02-06

    Organic room-temperature phosphorescence (ORTP), when combined with external stimuli-responsive capability, is very attractive for sensors and bio-imaging devices, but remains challenging. Herein, by doping two β-iminoenamine-BF 2 derivatives (S-2CN and S-2I) into a 4-iodoaniline (I-Ph-NH 2 ) crystalline matrix, the formation of S-2CN⋅⋅⋅I-Ph-NH 2 and S-2I⋅⋅⋅I-Ph-NH 2 halogen bonds leads to bright-red RTP emissions from these two host-guest doped crystals (hgDCs) with quantum efficiencies up to 13.43 % and 15.96 %, respectively. Upon treatment with HCl, the competition of I-Ph-NH 2 ⋅HCl formation against S-2I⋅⋅⋅I-Ph-NH 2 halogen bonding switches off the red RTP from S-2I/I-Ph-NH 2 hgDCs, whereas the stable halogen-bonded S-2CN⋅⋅⋅I-Ph-NH 2 ensures red RTP from S-2CN/I-Ph-NH 2 hgDCs remains unchanged. A security protection luminescence pattern by using these different HCl-responsive RTP behaviors was designed. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Interactions between volatile organic compounds and reactive halogen in the tropical marine atmosphere using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Badia, Alba; Reeves, Claire E.; Baker, Alex; Volkamer, Rainer; von Glasow, Roland

    2016-04-01

    Halogen species (chlorine, bromine and iodine) are known to play an important role in the chemistry and oxidizing capacity of the troposphere, particularly in the marine boundary layer (MBL). Reactive halogens cause ozone (O3) destruction, change the HOx and NOX partitioning, affect the oxidation of volatile organic compounds (VOCs) and mercury, reduce the lifetime of methane, and take part in new particle formation. Numerical models predicted that reactive halogen compounds account for 30% of O3 destruction in the MBL and 5-20% globally. There are indications that the chemistry of reactive halogens and oxygenated VOCs (OVOCs) in the tropics are inter-related. Moreover, the presence of aldehydes, such as glyoxal (CHOCHO), has a potential impact on radical cycling and secondary organic aerosol (SOA) formation in the MBL and free troposphere (FT). Model calculations suggest aldehydes to be an important sink for bromine atoms and hence competition for their reaction with O3 forming BrO and so illustrating a link between the cycles of halogens and OVOCs in the marine atmosphere. The main objective of this contribution is to investigate the atmospheric chemistry in the tropical East Pacific with a focus on reactive halogens and OVOCs and their links using the latest version of the Weather Research and Forecasting (WRF) model coupled with Chemistry (WRF-Chem) and field data from the TORERO campaign. WRF-Chem is a highly flexible community model for atmospheric research where aerosol-radiation-cloud feedback processes are taken into account. Our current reaction mechanism in WRF-Chem is based on the MOZART mechanism and has been extended to include bromine, chlorine and iodine chemistry. The MOZART mechanism includes detailed gas-phase chemistry of CHOCHO formation as well as state-of-the-science pathways to form SOA. Oceanic emissions of aldehydes, including CHOCHO, and of organic halogens based on measurements from the TORERO campaign have been added into the model. Sea

  12. Effect of halogenated impurities on lifetime of organic light emitting diode

    NASA Astrophysics Data System (ADS)

    Yamawaki, Hayato; Suzuki, Kunihiko; Kubota, Tomohiro; Watabe, Takeyoshi; Ishigaki, Ayumi; Nakamura, Rina; Inoue, Hideko; Nakashima, Harue; Horikoshi, Nozomi; Nowatari, Hiromi; Kataishi, Riho; Hamada, Toshiki; Sasaki, Toshiki; Suzuki, Tsunenori; Seo, Satoshi

    2016-09-01

    We investigated a correlation between lifetime and the halogen element concentration in an organic light-emitting diode (OLED) and conducted experiments and simulations to discuss degradation mechanisms due to the halogen. OELD is generally formed of high-purity materials. Since the synthesis of high-purity materials takes time and cost, quantitative understanding of the kind, amount, and influence of impurities in OLED devices is expected. The results of combustion ion chromatography show that, if the chlorine concentration in the host material is more than several parts per million, the lifetime of the device is drastically reduced. The chlorine element, which is derived from the chlorinated by-product of the host material, is found to be transferred from the chloride to other materials (e.g., an emissive dopant) according to the results of LC-MS analysis. In addition, the electron transport layer including such impurities is also found to adversely affect the lifetime. The results of TOF-SIMS analysis suggest that the dissociated chlorine element diffuse to the light-emitting layer side when the device is driven. The results of simulations (Gaussian 09) and electrochemical analyses (cyclic voltammetry and electrolysis) reveal that the halogen element is easy to dissociate from halide by excitation or reduction. The halogen element can repeat reactions with the peripheral materials by excitation or reduction and cause damages, e.g., generate radicals or further reaction products due to the radicals. The results of simulation suggest that, such compounds have low energy level and become quenchers.

  13. Method and apparatus for low temperature destruction of halogenated hydrocarbons

    DOEpatents

    Reagen, William Kevin; Janikowski, Stuart Kevin

    1999-01-01

    A method and apparatus for decomposing halogenated hydrocarbons are provided. The halogenated hydrocarbon is mixed with solvating agents and maintained in a predetermined atmosphere and at a predetermined temperature. The mixture is contacted with recyclable reactive material for chemically reacting with the recyclable material to create dehalogenated hydrocarbons and halogenated inorganic compounds. A feature of the invention is that the process enables low temperature destruction of halogenated hydrocarbons.

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

    PubMed

    Lim, Seung Joo; Fox, Peter

    2014-02-01

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

  15. What’s New in Enzymatic Halogenations

    PubMed Central

    Fujimori, Danica Galoniæ; Walsh, Christopher T.

    2007-01-01

    Summary The halogenation of thousands of natural products occurs during biosynthesis and often confers important functional properties. While haloperoxidases had been the default paradigm for enzymatic incorporation of halogens, via X+ equivalents into organic scaffolds, a combination of microbial genome sequencing, enzymatic studies and structural biology have provided deep new insights into enzymatic transfer of halide equivalents in three oxidation states. These are: (1) the halide ions (X−) abundant in nature, (2) halogen atoms (X•), and (3) the X+ equivalents. The mechanism of halogen incorporation is tailored to the electronic demands of specific substrates and involves enzymes with distinct redox coenzyme requirements. PMID:17881282

  16. 40 CFR 721.8675 - Halogenated pyridines.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8675 Halogenated pyridines. (a) Chemical substances and significant new uses subject to... subject to reporting under this section for the significant new uses described in paragraph (a)(1)(i) of...

  17. 40 CFR 721.8675 - Halogenated pyridines.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8675 Halogenated pyridines. (a) Chemical substances and significant new uses subject to... subject to reporting under this section for the significant new uses described in paragraph (a)(1)(i) of...

  18. 40 CFR 721.8675 - Halogenated pyridines.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8675 Halogenated pyridines. (a) Chemical substances and significant new uses subject to... subject to reporting under this section for the significant new uses described in paragraph (a)(1)(i) of...

  19. Process for the solvent extraction for the radiolysis and dehalogenation of halogenated organic compounds in soils, sludges, sediments and slurries

    DOEpatents

    Golden, Jeffry

    2007-02-13

    A process of extracting halogenated organic compounds, and particularly PCBs, from soil, sediment, slurry, sludge and dehalogenating the compounds contacts a contaminated soil sample with an extraction medium of a mixture of an alkane and a water miscible alcohol. The organic compounds dissolve in the extraction medium which is separated from the soil by passing water upwardly through the soil. The extraction medium floats to the surface of the water and is separated. Thereafter, the extraction medium containing the halogenated organic contaminants is subjected to ionizing radiation to radiolytically dehalogenate the compounds.

  20. Process for the solvent extraction for the radiolysis and dehalogenation of halogenated organic compounds in soils, sludges, sediments and slurries

    DOEpatents

    Mincher, Bruce J.; Curry, Randy Dale; Clevenger, Thomas E.; Golden, Jeffry

    2003-05-27

    A process of extracting halogenated organic compounds, and particularly PCBs, from soil, sediment, slurry, sludge and dehalogenating the compounds contacts a contaminated soil sample with an extraction medium of a mixture of an alkane and a water miscible alcohol. The organic compounds dissolve in the extraction medium which is separated from the soil by passing water upwardly through the soil. The extraction medium floats to the surface of the water and is separated. Thereafter, the extraction medium containing the halogenated organic contaminants is subjected to ionizing radiation to radiolytically dehalogenate the compounds.

  1. Process for the solvent extraction for the radiolysis and dehalogenation of halogenated organic compounds in soils, sludges, sediments and slurries

    DOEpatents

    Mincher, Bruce J.; Curry, Randy Dale; Clevenger, Thomas E.; Golden, Jeffry

    2000-01-01

    A process of extracting halogenated organic compounds, and particularly PCBs, from soil, sediment, slurry, sludge and dehalogenating the compounds contacting a contaminated soil sample with an extraction medium of a mixture of an alkane and a water miscible alcohol. The organic compounds dissolve in the extraction medium which is separated from the soil by passing water upwardly through the soil. The extraction medium floats to the surface of the water and is separated. Thereafter, the extraction medium containing the halogenated organic contaminants is subjected to ionizing radiation to radiolytically dehalogenate the compounds.

  2. Tropospheric Halogen Chemistry

    NASA Astrophysics Data System (ADS)

    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

  3. 40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 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...

  4. 40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

    Code of Federal Regulations, 2010 CFR

    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...

  5. 40 CFR 721.535 - Halogenated alkane (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Section 721.535 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.535 Halogenated alkane (generic). (a) Chemical substance and significant new uses subject to...

  6. Photochemically and Thermally Driven Full-Color Reflection in a Self-Organized Helical Superstructure Enabled by a Halogen-Bonded Chiral Molecular Switch.

    PubMed

    Wang, Hao; Bisoyi, Hari Krishna; Wang, Ling; Urbas, Augustine M; Bunning, Timothy J; Li, Quan

    2018-02-05

    Supramolecular approaches toward the fabrication of functional materials and systems have been an enabling endeavor. Recently, halogen bonding has been harnessed as a promising supramolecular tool. Herein we report the synthesis and characterization of a novel halogen-bonded light-driven axially chiral molecular switch. The photoactive halogen-bonded chiral switch is able to induce a self-organized, tunable helical superstructure, that is, cholesteric liquid crystal (CLC), when doped into an achiral liquid crystal (LC) host. The halogen-bonded switch as a chiral dopant has a high helical twisting power (HTP) and shows a large change of its HTP upon photoisomerization. This light-driven dynamic modulation enables reversible selective reflection color tuning across the entire visible spectrum. The chiral switch also displays a temperature-dependent HTP change that enables thermally driven red, green, and blue (RGB) reflection colors in the self-organized helical superstructure. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    PubMed

    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.

  8. Process for removal of hydrogen halides or halogens from incinerator gas

    DOEpatents

    Huang, Hann S.; Sather, Norman F.

    1988-01-01

    A process for reducing the amount of halogens and halogen acids in high temperature combustion gases 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.

  9. Process for removal of hydrogen halides or halogens from incinerator gas

    DOEpatents

    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.

  10. Nontargeted Screening of Halogenated Organic Compounds in Bottlenose Dolphins (Tursiops truncatus) from Rio de Janeiro, Brazil.

    PubMed

    Alonso, Mariana B; Maruya, Keith A; Dodder, Nathan G; Lailson-Brito, José; Azevedo, Alexandre; Santos-Neto, Elitieri; Torres, Joao P M; Malm, Olaf; Hoh, Eunha

    2017-02-07

    To catalog the diversity and abundance of halogenated organic compounds (HOCs) accumulating in high trophic marine species from the southwestern Atlantic Ocean, tissue from bottlenose dolphins (Tursiops truncatus) stranded or incidentally captured along the coast of Rio de Janeiro, Brazil, were analyzed by a nontargeted approach based on GC×GC/TOF-MS. A total of 158 individual HOCs from 32 different structural classes were detected in the blubber of 4 adult male T. truncatus. Nearly 90% of the detected compounds are not routinely monitored in the environment. DDT-related and mirex/dechlorane-related compounds were the most abundant classes of anthropogenic origin. Methoxy-brominated diphenyl ethers (MeO-BDEs) and chlorinated methyl- and dimethyl bipyrroles (MBPs and DMBPs) were the most abundant natural products. Reported for the first time in southwestern Atlantic cetaceans and in contrast to North American marine mammals, chlorinated MBPs and DMBPs were more abundant than their brominated and/or mixed halogenated counterparts. HOC profiles in coastal T. truncatus from Brazil and California revealed a distinct difference, with a higher abundance of MeO-BDEs, mirex/dechloranes and chlorinated bipyrroles in the Brazilian dolphins. Thirty-six percent of the detected HOCs had an unknown structure. These results suggest broad geographical differences in the patterns of bioaccumulative chemicals found in the marine environment and indicate the need to develop more complete catalogs of HOCs from various marine environments.

  11. A new halogen-free chemical oscillator: the reaction between permanganate ion and ninhydrin in a continuously stirred tank reactor

    NASA Astrophysics Data System (ADS)

    Treindl, Ľudovít; Nagy, Arpád

    1987-07-01

    The reaction between permanganate ion and ninhydrin in the presence of phosphoric acid in aqueous solution shows sustained oscillations in a continuously stirred tank reactor (CSTR). It exhibits a kinetic bistability between an oscillatory and a stationary state. Our new oscillating system seems to be a second permanganate chemical oscillator, thus broadening the small group of non-halogen-based chemical oscillators.

  12. 40 CFR 721.8875 - Substituted halogenated pyridinol.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8875 Substituted halogenated pyridinol. (a) Chemical substances and significant new uses... pyridinol (PMN P-88-1273) is subject to reporting under this section for the significant new uses described...

  13. 40 CFR 721.8750 - Halogenated substituted pyridine.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8750 Halogenated substituted pyridine. (a) Chemical substances and significant new uses... pyridine (PMN P-86-838) is subject to reporting under this section for the significant new uses described...

  14. 40 CFR 721.8875 - Substituted halogenated pyridinol.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8875 Substituted halogenated pyridinol. (a) Chemical substances and significant new uses... pyridinol (PMN P-88-1273) is subject to reporting under this section for the significant new uses described...

  15. 40 CFR 721.8850 - Disubstituted halogenated pyridinol.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8850 Disubstituted halogenated pyridinol. (a) Chemical substances and significant new uses... pyridinol (PMN P-88-1274) is subject to reporting under this section for the significant new uses described...

  16. 40 CFR 721.8850 - Disubstituted halogenated pyridinol.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8850 Disubstituted halogenated pyridinol. (a) Chemical substances and significant new uses... pyridinol (PMN P-88-1274) is subject to reporting under this section for the significant new uses described...

  17. 40 CFR 721.8750 - Halogenated substituted pyridine.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8750 Halogenated substituted pyridine. (a) Chemical substances and significant new uses... pyridine (PMN P-86-838) is subject to reporting under this section for the significant new uses described...

  18. 40 CFR 721.8850 - Disubstituted halogenated pyridinol.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8850 Disubstituted halogenated pyridinol. (a) Chemical substances and significant new uses... pyridinol (PMN P-88-1274) is subject to reporting under this section for the significant new uses described...

  19. 40 CFR 721.8875 - Substituted halogenated pyridinol.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8875 Substituted halogenated pyridinol. (a) Chemical substances and significant new uses... pyridinol (PMN P-88-1273) is subject to reporting under this section for the significant new uses described...

  20. 40 CFR 721.8750 - Halogenated substituted pyridine.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8750 Halogenated substituted pyridine. (a) Chemical substances and significant new uses... pyridine (PMN P-86-838) is subject to reporting under this section for the significant new uses described...

  1. 40 CFR 721.8875 - Substituted halogenated pyridinol.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8875 Substituted halogenated pyridinol. (a) Chemical substances and significant new uses... pyridinol (PMN P-88-1273) is subject to reporting under this section for the significant new uses described...

  2. 40 CFR 721.8750 - Halogenated substituted pyridine.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8750 Halogenated substituted pyridine. (a) Chemical substances and significant new uses... pyridine (PMN P-86-838) is subject to reporting under this section for the significant new uses described...

  3. 40 CFR 721.8875 - Substituted halogenated pyridinol.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8875 Substituted halogenated pyridinol. (a) Chemical substances and significant new uses... pyridinol (PMN P-88-1273) is subject to reporting under this section for the significant new uses described...

  4. 40 CFR 721.8850 - Disubstituted halogenated pyridinol.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8850 Disubstituted halogenated pyridinol. (a) Chemical substances and significant new uses... pyridinol (PMN P-88-1274) is subject to reporting under this section for the significant new uses described...

  5. 40 CFR 721.8750 - Halogenated substituted pyridine.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8750 Halogenated substituted pyridine. (a) Chemical substances and significant new uses... pyridine (PMN P-86-838) is subject to reporting under this section for the significant new uses described...

  6. 40 CFR 721.8850 - Disubstituted halogenated pyridinol.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8850 Disubstituted halogenated pyridinol. (a) Chemical substances and significant new uses... pyridinol (PMN P-88-1274) is subject to reporting under this section for the significant new uses described...

  7. 40 CFR 721.275 - Halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Halogenated-N-(2-propenyl)-N... New Uses for Specific Chemical Substances § 721.275 Halogenated-N-(2-propenyl)-N-(substituted phenyl... identified generically as halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide (P-83-1085) is subject...

  8. 40 CFR 721.275 - Halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halogenated-N-(2-propenyl)-N... New Uses for Specific Chemical Substances § 721.275 Halogenated-N-(2-propenyl)-N-(substituted phenyl... identified generically as halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide (P-83-1085) is subject...

  9. The halogen bond: Nature and applications

    NASA Astrophysics Data System (ADS)

    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.

  10. 40 CFR 721.8700 - Halogenated alkyl pyridine.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8700 Halogenated alkyl pyridine. (a) Chemical substances and significant new uses subject to... subject to reporting under this section for the significant new uses described in paragraph (a)(1)(i) of...

  11. 40 CFR 721.8700 - Halogenated alkyl pyridine.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8700 Halogenated alkyl pyridine. (a) Chemical substances and significant new uses subject to... subject to reporting under this section for the significant new uses described in paragraph (a)(1)(i) of...

  12. 40 CFR 65.154 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Halogen scrubbers and other halogen... Routing to a Fuel Gas System or a Process § 65.154 Halogen scrubbers and other halogen reduction devices. (a) Halogen scrubber and other halogen reduction device equipment and operating requirements. (1) An...

  13. Fine tuning of graphene properties by modification with aryl halogens

    NASA Astrophysics Data System (ADS)

    Bouša, D.; Pumera, M.; Sedmidubský, D.; Šturala, J.; Luxa, J.; Mazánek, V.; Sofer, Z.

    2016-01-01

    Graphene and its derivatives belong to one of the most intensively studied materials. The radical reaction using halogen derivatives of arene-diazonium salts can be used for effective control of graphene's electronic properties. In our work we investigated the influence of halogen atoms (fluorine, chlorine, bromine and iodine) as well as their position on the benzene ring towards the electronic and electrochemical properties of modified graphenes. The electronegativity as well as the position of the halogen atoms on the benzene ring has crucial influence on graphene's properties due to the inductive and mesomeric effects. The results of resistivity measurement are in good agreement with the theoretical calculations of electron density within chemically modified graphene sheets. Such simple chemical modifications of graphene can be used for controllable and scalable synthesis of graphene with tunable transport properties.Graphene and its derivatives belong to one of the most intensively studied materials. The radical reaction using halogen derivatives of arene-diazonium salts can be used for effective control of graphene's electronic properties. In our work we investigated the influence of halogen atoms (fluorine, chlorine, bromine and iodine) as well as their position on the benzene ring towards the electronic and electrochemical properties of modified graphenes. The electronegativity as well as the position of the halogen atoms on the benzene ring has crucial influence on graphene's properties due to the inductive and mesomeric effects. The results of resistivity measurement are in good agreement with the theoretical calculations of electron density within chemically modified graphene sheets. Such simple chemical modifications of graphene can be used for controllable and scalable synthesis of graphene with tunable transport properties. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06295k

  14. Impact of Enhanced Ozone Deposition and Halogen Chemistry on Tropospheric Ozone over the Northern Hemisphere.

    PubMed

    Sarwar, Golam; Gantt, Brett; Schwede, Donna; Foley, Kristen; Mathur, Rohit; Saiz-Lopez, Alfonso

    2015-08-04

    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 chemistry in a comprehensive atmospheric modeling system. The enhanced ozone deposition treatment accounts for the interaction of iodide in seawater with ozone and increases deposition velocities by 1 order of magnitude. Halogen chemistry includes detailed chemical reactions of organic and inorganic bromine and iodine species. Two different simulations are completed with the halogen chemistry: without and with photochemical reactions of higher iodine oxides. Enhanced deposition reduces mean summer-time surface ozone by ∼3% over marine regions in the Northern Hemisphere. Halogen chemistry without the photochemical reactions of higher iodine oxides reduces surface ozone by ∼15% whereas simulations with the photochemical reactions of higher iodine oxides indicate ozone reductions of ∼48%. The model without these processes overpredicts ozone compared to observations whereas the inclusion of these processes improves predictions. The inclusion of photochemical reactions for higher iodine oxides leads to ozone predictions that are lower than observations, underscoring the need for further refinement of the halogen emissions and chemistry scheme in the model.

  15. Halogenated volatile organic compounds in chlorine-bleach-containing household products and implications for their use

    NASA Astrophysics Data System (ADS)

    Odabasi, Mustafa; Elbir, Tolga; Dumanoglu, Yetkin; Sofuoglu, Sait C.

    2014-08-01

    It was recently shown that substantial amounts of halogenated volatile organic compounds (VOCs) are formed in chlorine-bleach-containing household products as a result of reactions of sodium hypochlorite with organic product components. Use of these household products results in elevated indoor air halogenated VOC concentrations. Halogenated VOCs in several chlorine-bleach-containing household products (plain, n = 9; fragranced, n = 4; and surfactant-added, n = 29) from Europe and North America were measured in the present study. Chloroform and carbon tetrachloride were the dominating compounds having average concentrations of 9.5 ± 29.0 (average ± SD) and 23.2 ± 44.3 (average ± SD) mg L-1, respectively. Halogenated VOC concentrations were the lowest in plain bleach, slightly higher in fragranced products and the highest in the surfactant-added products. Investigation of the relationship between the halogenated VOCs and several product ingredients indicated that chlorinated VOC formation is closely related to product composition. Indoor air concentrations from the household use of bleach products (i.e., bathroom, kitchen, and hallway cleaning) were estimated for the two dominating VOCs (chloroform and carbon tetrachloride). Estimated indoor concentrations ranged between 0.5 and 1030 (34 ± 123, average ± SD) μg m-3 and 0.3-1124 (82 ± 194, average ± SD) μg m-3 for chloroform and carbon tetrachloride, respectively, indicating substantial increases compared to background. Results indicated that indoor air concentrations from surfactant-added products were significantly higher (p < 0.01) than other categories. The highest concentrations were from the use of surfactant-added bleach products for bathroom cleaning (92 ± 228 and 224 ± 334 μg m-3, average ± SD for chloroform and carbon tetrachloride, respectively). Associated carcinogenic risks from the use of these products were also estimated. The risk levels may reach to considerably high levels for a

  16. Organic halogenated contaminants in mother-fetus pairs of harbor seals (Phoca vitulina richardii) from Alaska, 2000-2002

    USDA-ARS?s Scientific Manuscript database

    Environmental stressors may interfere with foraging, survival and reproduction of marine mammals resulting in marine mammal population decline. In this study, organic halogenated pollutants [OHs, including organochlorine pesticides, polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCN...

  17. Sensitivity of Tropospheric Chemical Composition to Halogen-Radical Chemistry Using a Fully Coupled Size-Resolved Multiphase Chemistry-Global Climate System: Halogen Distributions, Aerosol Composition, and Sensitivity of Climate-Relevant Gases

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Long, M.; Keene, W. C.; Easter, Richard C.

    Observations and model studies suggest a significant but highly non-linear role for halogens, primarily Cl and Br, in multiphase atmospheric processes relevant to tropospheric chemistry and composition, aerosol evolution, radiative transfer, weather, and climate. The sensitivity of global atmospheric chemistry to the production of marine aerosol and the associated activation and cycling of inorganic Cl and Br was tested using a size-resolved multiphase coupled chemistry/global climate model (National Center for Atmospheric Research’s Community Atmosphere Model (CAM); v3.6.33). Simulation results showed strong meridional and vertical gradients in Cl and Br species. The simulation reproduced most available observations with reasonable confidence permittingmore » the formulation of potential mechanisms for several previously unexplained halogen phenomena including the enrichment of Br- in submicron aerosol, and the presence of a BrO maximum in the polar free troposphere. However, simulated total volatile Br mixing ratios were generally high in the troposphere. Br in the stratosphere was lower than observed due to the lack of long-lived organobromine species in the simulation. Comparing simulations using chemical mechanisms with and without reactive Cl and Br species demonstrated a significant temporal and spatial sensitivity of primary atmospheric oxidants (O3, HOx, NOx), CH4, and non-methane hydrocarbons (NMHC’s) to halogen cycling. Simulated O3 and NOx were globally lower (65% and 35%, respectively, less in the planetary boundary layer based on median values) in simulations that included halogens. Globally, little impact was seen in SO2 and non-sea-salt SO42- processing due to halogens. Significant regional differences were evident: The lifetime of nss-SO42- was extended downwind of large sources of SO2. The burden and lifetime of DMS (and its oxidation products) were lower by a factor of 5 in simulations that included halogens, versus those without, leading

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

    PubMed

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

    2018-02-20

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

  19. Low-Level detections of halogenated volatile organic compounds in groundwater: Use in vulnerability assessments

    USGS Publications Warehouse

    Plummer, Niel; Busenberg, E.; Eberts, S.M.; Bexfield, L.M.; Brown, C.J.; Fahlquist, L.S.; Katz, B.G.; Landon, M.K.

    2008-01-01

    Concentrations of halogenated volatile organic compounds (VOCs) were determined by gas chromatography (GC) with an electron-capture detector (GC-ECD) and by gas chromatography with mass spectrometry (GC-MS) in 109 groundwater samples from five study areas in the United States. In each case, the untreated water sample was used for drinking-water purposes or was from a monitoring well in an area near a drinking-water source. The minimum detection levels (MDLs) for 25 VOCs that were identified in GC-ECD chromatograms, typically, were two to more than four orders of magnitude below the GC-MS MDLs. At least six halogenated VOCs were detected in all of the water samples analyzed by GC-ECD, although one or more VOCs were detected in only 43% of the water samples analyzed by GC-MS. In nearly all of the samples, VOC concentrations were very low and presented no known health risk. Most of the low-level VOC detections indicated post-1940s recharge, or mixtures of recharge that contained a fraction of post-1940s water. Concentrations of selected halogenated VOCs in groundwater from natural and anthropogenic atmospheric sources were estimated and used to recognize water samples that are being impacted by nonatmospheric sources. A classification is presented to perform vulnerability assessments at the scale of individual wells using the number of halogenated VOC detections and total dissolved VOC concentrations in samples of untreated drinking water. The low-level VOC detections are useful in vulnerability assessments, particularly for samples in which no VOCs are detected by GC-MS analysis.

  20. 3D-QSAR based on quantum-chemical molecular fields: toward an improved description of halogen interactions.

    PubMed

    Güssregen, Stefan; Matter, Hans; Hessler, Gerhard; Müller, Marco; Schmidt, Friedemann; Clark, Timothy

    2012-09-24

    Current 3D-QSAR methods such as CoMFA or CoMSIA make use of classical force-field approaches for calculating molecular fields. Thus, they can not adequately account for noncovalent interactions involving halogen atoms like halogen bonds or halogen-π interactions. These deficiencies in the underlying force fields result from the lack of treatment of the anisotropy of the electron density distribution of those atoms, known as the "σ-hole", although recent developments have begun to take specific interactions such as halogen bonding into account. We have now replaced classical force field derived molecular fields by local properties such as the local ionization energy, local electron affinity, or local polarizability, calculated using quantum-mechanical (QM) techniques that do not suffer from the above limitation for 3D-QSAR. We first investigate the characteristics of QM-based local property fields to show that they are suitable for statistical analyses after suitable pretreatment. We then analyze these property fields with partial least-squares (PLS) regression to predict biological affinities of two data sets comprising factor Xa and GABA-A/benzodiazepine receptor ligands. While the resulting models perform equally well or even slightly better in terms of consistency and predictivity than the classical CoMFA fields, the most important aspect of these augmented field-types is that the chemical interpretation of resulting QM-based property field models reveals unique SAR trends driven by electrostatic and polarizability effects, which cannot be extracted directly from CoMFA electrostatic maps. Within the factor Xa set, the interaction of chlorine and bromine atoms with a tyrosine side chain in the protease S1 pocket are correctly predicted. Within the GABA-A/benzodiazepine ligand data set, PLS models of high predictivity resulted for our QM-based property fields, providing novel insights into key features of the SAR for two receptor subtypes and cross

  1. Halogen-bonding-triggered supramolecular gel formation

    NASA Astrophysics Data System (ADS)

    Meazza, Lorenzo; Foster, Jonathan A.; Fucke, Katharina; Metrangolo, Pierangelo; Resnati, Giuseppe; Steed, Jonathan W.

    2013-01-01

    Supramolecular gels are topical soft materials involving the reversible formation of fibrous aggregates using non-covalent interactions. There is significant interest in controlling the properties of such materials by the formation of multicomponent systems, which exhibit non-additive properties emerging from interaction of the components. The use of hydrogen bonding to assemble supramolecular gels in organic solvents is well established. In contrast, the use of halogen bonding to trigger supramolecular gel formation in a two-component gel (‘co-gel’) is essentially unexplored, and forms the basis for this study. Here, we show that halogen bonding between a pyridyl substituent in a bis(pyridyl urea) and 1,4-diiodotetrafluorobenzene brings about gelation, even in polar media such as aqueous methanol and aqueous dimethylsulfoxide. This demonstrates that halogen bonding is sufficiently strong to interfere with competing gel-inhibitory interactions and create a ‘tipping point’ in gel assembly. Using this concept, we have prepared a halogen bond donor bis(urea) gelator that forms co-gels with halogen bond acceptors.

  2. Degradation of halogenated aliphatic compounds by Xanthobacter autotrophicus GJ10.

    PubMed Central

    Janssen, D B; Scheper, A; Dijkhuizen, L; Witholt, B

    1985-01-01

    A bacterium that is able to utilize a number of halogenated short-chain hydrocarbons and halogenated carboxylic acids as sole carbon source for growth was identified as a strain of Xanthobacter autotrophicus. The organism constitutively produces two different dehalogenases. One enzyme is specific for halogenated alkanes, whereas the other, which is more heat stable and has a higher pH optimum, is specific for halogenated carboxylic acids. Haloalkanes were hydrolyzed in cell extracts to produce alcohols and halide ions, and a route for the metabolism of 1,2-dichlorethane is proposed. Both dehalogenases show a broad substrate specificity, allowing the degradation of bromine- and chlorine-substituted organic compounds. The results show that X. autotrophicus may play a role in the degradation of organochlorine compounds and that hydrolytic dehalogenases may be involved in the microbial metabolism of short-chain halogenated hydrocarbons in microorganisms. Images PMID:3994371

  3. Fluorescence spectroscopy for monitoring reduction of natural organic matter and halogenated furanone precursors by biofiltration.

    PubMed

    Peleato, Nicolás M; McKie, Michael; Taylor-Edmonds, Lizbeth; Andrews, Susan A; Legge, Raymond L; Andrews, Robert C

    2016-06-01

    The application of fluorescence spectroscopy to monitor natural organic matter (NOM) reduction as a function of biofiltration performance was investigated. This study was conducted at pilot-scale where a conventional media filter was compared to six biofilters employing varying enhancement strategies. Overall reductions of NOM were identified by measuring dissolved organic carbon (DOC), and UV absorbance at 254 nm, as well as characterization of organic sub-fractions by liquid chromatography-organic carbon detection (LC-OCD) and parallel factors analysis (PARAFAC) of fluorescence excitation-emission matrices (FEEM). The biofilter using granular activated carbon media, with exhausted absorptive capacity, was found to provide the highest removal of all identified PARAFAC components. A microbial or processed humic-like component was found to be most amenable to biodegradation by biofilters and removal by conventional treatment. One refractory humic-like component, detectable only by FEEM-PARAFAC, was not well removed by biofiltration or conventional treatment. All biofilters removed protein-like material to a high degree relative to conventional treatment. The formation potential of two halogenated furanones, 3-chloro-4(dichloromethyl)-2(5H)-furanone (MX) and mucochloric acid (MCA), as well as overall treated water genotoxicity are also reported. Using the organic characterization results possible halogenated furanone and genotoxicity precursors are identified. Comparison of FEEM-PARAFAC and LC-OCD results revealed polysaccharides as potential MX/MCA precursors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. 40 CFR 63.994 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... halogen scrubber or other halogen reduction technique used to reduce the vent stream halogen atom mass... subpart shall determine the halogen atom mass emission rate prior to the combustion device according to...

  5. 40 CFR 63.994 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... halogen scrubber or other halogen reduction technique used to reduce the vent stream halogen atom mass... subpart shall determine the halogen atom mass emission rate prior to the combustion device according to...

  6. 40 CFR 63.994 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... halogen scrubber or other halogen reduction technique used to reduce the vent stream halogen atom mass... subpart shall determine the halogen atom mass emission rate prior to the combustion device according to...

  7. 40 CFR 63.994 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... halogen scrubber or other halogen reduction technique used to reduce the vent stream halogen atom mass... subpart shall determine the halogen atom mass emission rate prior to the combustion device according to...

  8. 40 CFR 63.994 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... halogen scrubber or other halogen reduction technique used to reduce the vent stream halogen atom mass... subpart shall determine the halogen atom mass emission rate prior to the combustion device according to...

  9. Halogen-Mediated Conversion of Hydrocarbons to Commodities.

    PubMed

    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.

  10. Experimental and computational evidence of halogen bonds involving astatine

    NASA Astrophysics Data System (ADS)

    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.

  11. Halogenated methanesulfonic acids: A new class of organic micropollutants in the water cycle.

    PubMed

    Zahn, Daniel; Frömel, Tobias; Knepper, Thomas P

    2016-09-15

    Mobile and persistent organic micropollutants may impact raw and drinking waters and are thus of concern for human health. To identify such possible substances of concern nineteen water samples from five European countries (France, Switzerland, The Netherlands, Spain and Germany) and different compartments of the water cycle (urban effluent, surface water, ground water and drinking water) were enriched with mixed-mode solid phase extraction. Hydrophilic interaction liquid chromatography - high resolution mass spectrometry non-target screening of these samples led to the detection and structural elucidation of seven novel organic micropollutants. One structure could already be confirmed by a reference standard (trifluoromethanesulfonic acid) and six were tentatively identified based on experimental evidence (chloromethanesulfonic acid, dichloromethanesulfonic acid, trichloromethanesulfonic acid, bromomethanesulfonic acid, dibromomethanesulfonic acid and bromochloromethanesulfonic acid). Approximated concentrations for these substances show that trifluoromethanesulfonic acid, a chemical registered under the European Union regulation REACH with a production volume of more than 100 t/a, is able to spread along the water cycle and may be present in concentrations up to the μg/L range. Chlorinated and brominated methanesulfonic acids were predominantly detected together which indicates a common source and first experimental evidence points towards water disinfection as a potential origin. Halogenated methanesulfonic acids were detected in drinking waters and thus may be new substances of concern. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Defect engineered oxides for enhanced mechanochemical destruction of halogenated organic pollutants.

    PubMed

    Cagnetta, Giovanni; Huang, Jun; Lu, Mengnan; Wang, Bin; Wang, Yujue; Deng, Shubo; Yu, Gang

    2017-10-01

    Mechanochemical activation of metal oxides is studied by a novel methodology based on solid state reaction with a stable radical specie. Such approach corroborates that vacancy formation by high energy ball milling, also in nonreducible oxides, is responsible for electron release on particles' surfaces. This finding suggests a new defect engineering strategy to improve effectiveness of metal oxides as co-milling reagent for halogenated organic pollutant destruction. Results prove that high valent metal doping of a commonly employed co-milling reagent such as CaO determines 2.5 times faster pollutant degradation rate. This enhancement is due to electron-rich defects generated by the dopant; electrons are transferred to the organic pollutant thus causing its mineralization. The proposed strategy can be easily applied to other reagents. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Halogen dependent symmetry change in two series of wheel cluster organic frameworks built from La18 tertiary building units.

    PubMed

    Fang, Wei-Hui; Zhang, Lei; Zhang, Jian; Yang, Guo-Yu

    2016-01-25

    Two series of wheel cluster organic frameworks (WCOFs) built from La18 tertiary building units are hydrothermally made, which show halogen-dependent structural symmetry, and demonstrate different chiral performances.

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

    PubMed

    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

  15. Selection criteria for oxidation method in total organic carbon measurement.

    PubMed

    Yoon, GeunSeok; Park, Sang-Min; Yang, Heuiwon; Tsang, Daniel C W; Alessi, Daniel S; Baek, Kitae

    2018-05-01

    During the measurement of total organic carbon (TOC), dissolved organic carbon is converted into CO 2 by using high temperature combustion (HTC) or wet chemical oxidation (WCO). However, the criteria for selecting the oxidation methods are not clear. In this study, the chemical structures of organic material were considered as a key factor to select the oxidation method used. Most non-degradable organic compounds showed a similar oxidation efficiency in both methods, including natural organic compounds, dyes, and pharmaceuticals, and thus both methods are appropriate to measure TOC in waters containing these compounds. However, only a fraction of the carbon in the halogenated compounds (perfluorooctanoic acid and trifluoroacetic acid) were oxidized using WCO, resulting in measured TOC values that are considerably lower than those determined by HTC. This result is likely due to the electronegativity of halogen elements which inhibits the approach of electron-rich sulfate radicals in the WCO, and the higher bond strength of carbon-halogen pairs as compared to carbon-hydrogen bonds, which results in a lower degree of oxidation of the compounds. Our results indicate that WCO could be used to oxidize most organic compounds, but may not be appropriate to quantify TOC in organic carbon pools that contain certain halogenated compounds. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Structural Perspective on Enzymatic Halogenation

    PubMed Central

    2008-01-01

    and chemistry of these enzymes. In particular, the latest crystallographic snapshots of active site architecture and halide binding sites have provided key insights into enzyme catalysis. Herein is a summary of the five classes of halogenases, focusing on the three most recently discovered: flavin-dependent halogenases, non-heme iron-dependent halogenases, and nucleophilic halogenases. Further, the potential roles of halide-binding sites in determining halide selectivity are discussed, as well as whether or not binding-site composition is always a seminal factor for selectivity. Expanding our understanding of the basic chemical principles that dictate the activity of the halogenases will advance both biology and chemistry. A thorough mechanistic analysis will elucidate the biological principles that dictate specificity, and the application of those principles to new synthetic techniques will expand the utility of halogenations in small-molecule development. PMID:18774824

  17. The gas-chromatographic and gas-chromatographic-mass-spectrometric identification of halogen-containing organic compounds

    NASA Astrophysics Data System (ADS)

    Gidaspov, B. V.; Zenkevich, I. G.; Rodin, A. A.

    1989-09-01

    The problem of identifying halogen-containing organic compounds in their gas-chromatographic and gas-chromatographic-mass-spectrometric (GC-MS) determination in different materials has been examined. Particular attention has been paid not to the complete characterisation of methods for carrying out this analysis but to the most important problem of increasing the selectivity at the stages of sampling, separation, and interpretation of the gas-chromatographic and GC-MS information. The bibliography contains 292 references.

  18. Halogens in chondritic meteorites and terrestrial accretion

    NASA Astrophysics Data System (ADS)

    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

  19. VOLATILE ORGANIC CHEMICALS IN 10 PUBLIC-ACCESS BUILDINGS

    EPA Science Inventory

    The U.S. EPA carried out studies of indoor air quality in 10 buildings. Qualitative analysis identified over 200 aromatics, halogens, esters, alcohols, phenols, ethers, ketones, aldehydes, and epoxides, in addition to several hundred aliphatic hydrocarbons. The total organic load...

  20. Headspace GC-MS Analysis of Halogenated Volatile Organic Compounds in Aqueous Samples: An Experiment for General Chemistry Laboratory

    ERIC Educational Resources Information Center

    Keller, John W.; Fabbri, Cindy E.

    2012-01-01

    Analysis of halogenated volatile organic compounds (HVOCs) by GC-MS demonstrates the use of instrumentation in the environmental analysis of pollutant molecules and enhances student understanding of stable isotopes in nature. In this experiment, students separated and identified several HVOCs that have been implicated as industrial groundwater…

  1. Halogens and the Chemistry of the Free Troposphere

    NASA Technical Reports Server (NTRS)

    Lary, David John

    2004-01-01

    The role of halogens in both the marine boundary layer and the stratosphere has long been recognized, while their role in the free troposphere is often not considered in global chemical models. However, a careful examination of free-tropospheric chemistry constrained by observations using a full chemical data assimilation system shows that halogens do play a significant role in the free troposphere. In particular, the chlorine initiation of methane oxidation in the free troposphere can contribute more than 10%, and in some regions up to 50%, of the total rate of initiation. The initiation of methane oxidation by chlorine is particularly important below the polar vortex and in northern mid-latitudes. Likewise, the hydrolysis of BrONO2 alone can contribute more than 35% of the HNO3 production rate in the free-troposphere.

  2. Insights into enzymatic halogenation from computational studies

    PubMed Central

    Senn, Hans M.

    2014-01-01

    The halogenases are a group of enzymes that have only come to the fore over the last 10 years thanks to the discovery and characterization of several novel representatives. They have revealed the fascinating variety of distinct chemical mechanisms that nature utilizes to activate halogens and introduce them into organic substrates. Computational studies using a range of approaches have already elucidated many details of the mechanisms of these enzymes, often in synergistic combination with experiment. This Review summarizes the main insights gained from these studies. It also seeks to identify open questions that are amenable to computational investigations. The studies discussed herein serve to illustrate some of the limitations of the current computational approaches and the challenges encountered in computational mechanistic enzymology. PMID:25426489

  3. [Application of quantum-chemical methods to prediction of the carcinogenicity of chemical substances].

    PubMed

    Zholdikova, Z I; Kharchevnikova, N V

    2006-01-01

    A version of logical-combinatorial JSM type intelligent system was used to predict the presence and the degree of a carcinogenic effect. This version was based on combined description of chemical substances including both structural and numeric parameters. The new version allows for the fact that the toxicity and danger caused by chemical substances often depend on their biological activation in the organism. The authors substantiate classifying chemicals according to their carcinogenic activity, and illustrate the use of the system to predict the carcinogenicity of polycyclic aromatic hydrocarbons using a model of bioactivation via the formation of diolepoxides, and the carcinogenicity of halogenated alkanes using a model of bioactivation via oxidative dehalogenation. The paper defined the boundary level of an energetic parameter, the exceeding of which correlated with the inhibition of halogenated alkanes's metabolism and the absence of carcinogenic activity.

  4. Metal-Mediated Halogen Exchange in Aryl and Vinyl Halides: A Review

    PubMed Central

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

    2018-01-01

    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. PMID:29755967

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Biodegradation of Trihalomethanes and Other Halogenated Aliphatic Compounds

    NASA Technical Reports Server (NTRS)

    Smith, G. B.

    1996-01-01

    The biological dehalogenation of common water pollutants such as trichloromethane (chloroform) and other halogenated aliphatic compounds was the subject of this project. Samples from diverse water environments such as from groundwater contaminated with halogenated compounds and wastewaters from regional treatment plants were studied to identify conditions that favor certain dehalogenation reactions over others. Gene probe analyses of DNA extracted from the dichlormethane-degrading wastewater indicated the presence of the gene coding for dichloromethane dehalogenase, indicating the genetic basis for the dechlorination activity observed. These studies indicate that methanogenic bacteria are the organisms responsible for the chloroform dechlorination. Dechlorination of a common chlorofluorocarbon (CFC-11) was identified in samples taken from a regional aquifer contaminated with halogenated aliphatic compounds.

  7. Natural Abundance 15 N and 13 C Solid-State NMR Chemical Shifts: High Sensitivity Probes of the Halogen Bond Geometry.

    PubMed

    Cerreia Vioglio, Paolo; Catalano, Luca; Vasylyeva, Vera; Nervi, Carlo; Chierotti, Michele R; Resnati, Giuseppe; Gobetto, Roberto; Metrangolo, Pierangelo

    2016-11-14

    Solid-state nuclear magnetic resonance (SSNMR) spectroscopy is a versatile characterization technique that can provide a plethora of information complementary to single crystal X-ray diffraction (SCXRD) analysis. Herein, we present an experimental and computational investigation of the relationship between the geometry of a halogen bond (XB) and the SSNMR chemical shifts of the non-quadrupolar nuclei either directly involved in the interaction ( 15 N) or covalently bonded to the halogen atom ( 13 C). We have prepared two series of X-bonded co-crystals based upon two different dipyridyl modules, and several halobenzenes and diiodoalkanes, as XB-donors. SCXRD structures of three novel co-crystals between 1,2-bis(4-pyridyl)ethane, and 1,4-diiodobenzene, 1,6-diiodododecafluorohexane, and 1,8-diiodohexadecafluorooctane were obtained. For the first time, the change in the 15 N SSNMR chemical shifts upon XB formation is shown to experimentally correlate with the normalized distance parameter of the XB. The same overall trend is confirmed by density functional theory (DFT) calculations of the chemical shifts. 13 C NQS experiments show a positive, linear correlation between the chemical shifts and the C-I elongation, which is an indirect probe of the strength of the XB. These correlations can be of general utility to estimate the strength of the XB occurring in diverse adducts by using affordable SSNMR analysis. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Nontargeted Biomonitoring of Halogenated Organic Compounds in Two Ecotypes of Bottlenose Dolphins (Tursiops truncatus) from the Southern California Bight

    PubMed Central

    2015-01-01

    Targeted environmental monitoring reveals contamination by known chemicals, but may exclude potentially pervasive but unknown compounds. Marine mammals are sentinels of persistent and bioaccumulative contaminants due to their longevity and high trophic position. Using nontargeted analysis, we constructed a mass spectral library of 327 persistent and bioaccumulative compounds identified in blubber from two ecotypes of common bottlenose dolphins (Tursiops truncatus) sampled in the Southern California Bight. This library of halogenated organic compounds (HOCs) consisted of 180 anthropogenic contaminants, 41 natural products, 4 with mixed sources, 8 with unknown sources, and 94 with partial structural characterization and unknown sources. The abundance of compounds whose structures could not be fully elucidated highlights the prevalence of undiscovered HOCs accumulating in marine food webs. Eighty-six percent of the identified compounds are not currently monitored, including 133 known anthropogenic chemicals. Compounds related to dichlorodiphenyltrichloroethane (DDT) were the most abundant. Natural products were, in some cases, detected at abundances similar to anthropogenic compounds. The profile of naturally occurring HOCs differed between ecotypes, suggesting more abundant offshore sources of these compounds. This nontargeted analytical framework provided a comprehensive list of HOCs that may be characteristic of the region, and its application within monitoring surveys may suggest new chemicals for evaluation. PMID:25526519

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

    NASA Astrophysics Data System (ADS)

    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

  10. Halogen lamp experiment, HALEX

    NASA Technical Reports Server (NTRS)

    Schmitt, G.; Stapelmann, J.

    1986-01-01

    The main purpose of the Halogen Lamp Experiment (HALEX) was to investigate the operation of a halogen lamp during an extended period in a microgravity environment and to prove its behavior in space. The Mirror Heating Facilities for Crystal Growth and Material Science Experiments in space relies on one or two halogen lamps as a furnace to melt the specimens. The HALEX aim is to verify: full power operation of a halogen lamp for a period of about 60 hours; achievement of about 10% of its terrestrial life span; and operation of the halogen lamp under conditions similar to furnace operation.

  11. The Halogen Bond

    PubMed Central

    2016-01-01

    The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design. PMID:26812185

  12. The relation between molecular structure and biological activity among mononitrophenols containing halogens

    USGS Publications Warehouse

    Applegate, Vernon C.; Johnson, B.G.H.; Smith, Manning A.

    1966-01-01

    The results of tests of the biological activity of certain nitrophenols containing halogen are reported. Some of these are shown to be significantly more toxic to larvae of the sea lamprey (Petromyzon marinus L.) than to fishes. It is proposed that the death of lamprey larvae exposed to these compounds results from an acute hypotension (shock) with concomitant circulatory and respiratory failure. Rainbow trout (Salmo gairdneri), on the other hand, appear to die, at higher concentrations of the toxin, due to a chemically-caused mechanical interference with respiration through the gills. A systematic series of studies of mononitrophenols containing halogens disclosed that those phenols having the nitro group in the para-position and a halogen atom or group in the meta-position are generally more toxic to lampreys than to fish. The halogens or halogen groups used in this study were fluorine, chlorine, bromine, and trifluormethyl. The same substituents in other positions only occasionally gave rise to selectively toxic compounds. The relationship between the selectively active class of nitrophenols containing halogens and other related structures is discussed.

  13. Designing safer chemicals: Predicting the rates of metabolism of halogenated alkanes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yin, H.; Anders, M.W.; Higgins, L.

    1995-11-21

    A computational model is presented that can be used as a tool in the design of safer chemicals. This model predicts that rate of hydrogen-atom abstraction by cytochrome P450 enzymes. Excellent correlations between biotransformation rates and the calculated activation energies ({Delta}H{sub act}) of the cytochrome P450-mediated hydrogen-atom abstractions were obtained for the in vitro biotransformation of six halogenated alkanes (1-fluoro-1,1,1,2,2-tetrachloroethane, 1,1,1,2-tetrafluoro-2-chloroethane, 1,1,1,2,2-pentafluoroethane, and 2-bromo-2-chloro-1,1,1-trifluoroethane) with both rat and human enzyme preparations: (rate, human CYP2E1) = 44.99 - 1.79 ({Delta}H{sub act}), r{sup 2} = 0.86; In (rate, human Cyp2E1)= 46399 -1.77 ({Delta}H{sub act}), r{sup 2} = 0.97 (rates are in nmolmore » of product per min per nmol of cytochrome P450 and energies are in kcal/mol). Correlations were also obtained for five inhalation anesthetics (enflurane, sevoflurane, desflurane, methoxyflurane, and isoflurane) for both in vivo and in vitro data have been shown to agree in any species. The model presented herein provides an archetype for the methodology that may be used in the future design of safer chemicals, particularly hydrochlorofluorocarbons and inhalation anesthetics. 41 refs., 1 fig., 2 tabs.« less

  14. Halogen radicals contribute to photooxidation in coastal and estuarine waters

    PubMed Central

    Parker, Kimberly M.; Mitch, William A.

    2016-01-01

    Although halogen radicals are recognized to form as products of hydroxyl radical (•OH) scavenging by halides, their contribution to the phototransformation of marine organic compounds has received little attention. We demonstrate that, relative to freshwater conditions, seawater halides can increase photodegradation rates of domoic acid, a marine algal toxin, and dimethyl sulfide, a volatile precursor to cloud condensation nuclei, up to fivefold. Using synthetic seawater solutions, we show that the increased photodegradation is specific to dissolved organic matter (DOM) and halides, rather than other seawater salt constituents (e.g., carbonates) or photoactive species (e.g., iron and nitrate). Experiments in synthetic and natural coastal and estuarine water samples demonstrate that the halide-specific increase in photodegradation could be attributed to photochemically generated halogen radicals rather than other photoproduced reactive intermediates [e.g., excited-state triplet DOM (3DOM*), reactive oxygen species]. Computational kinetic modeling indicates that seawater halogen radical concentrations are two to three orders of magnitude greater than freshwater •OH concentrations and sufficient to account for the observed halide-specific increase in photodegradation. Dark •OH generation by gamma radiolysis demonstrates that halogen radical production via •OH scavenging by halides is insufficient to explain the observed effect. Using sensitizer models for DOM chromophores, we show that halogen radicals are formed predominantly by direct oxidation of Cl− and Br− by 3DOM*, an •OH-independent pathway. Our results indicate that halogen radicals significantly contribute to the phototransformation of algal products in coastal or estuarine surface waters. PMID:27162335

  15. 75 FR 70248 - Endocrine Disruptor Screening Program; Second List of Chemicals for Tier 1 Screening

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-17

    ...., persons who manufacture, import or process chemical substances. Pesticide, fertilizer, and other... pesticide, fertilizer and agricultural chemicals. Scientific research and development services (NAICS code... water contaminants, such as halogenated organic chemicals, dioxins, flame retardants (PBDEs, PCBs, PFCs...

  16. Comparison of dermal and inhalation routes of entry for organic chemicals

    NASA Technical Reports Server (NTRS)

    Jepson, Gary W.; Mcdougal, James N.; Clewell, Harvey J., III

    1992-01-01

    The quantitative comparison of the chemical concentration inside the body as the result of a dermal exposure versus an inhalation exposure is useful for assessing human health risks and deciding on an appropriate protective posture. In order to describe the relationship between dermal and inhalation routes of exposure, a variety of organic chemicals were evaluated. The types of chemicals chosen for the study were halogenated hydrocarbons, aromatic compounds, non-polar hydrocarbons and inhalation anesthetics. Both dermal and inhalation exposures were conducted in rats and the chemicals were in the form of vapors. Prior to the dermal exposure, rat fur was closely clipped and during the exposure rats were provided fresh breathing air through latex masks. Blood samples were taken during 4-hour exposures and analyzed for the chemical of interest. A physiologically based pharmacokinetic model was used to predict permeability constants (cm/hr) consistent with the observed blood concentrations of the chemical. The ratio of dermal exposure to inhalation exposure required to achieve the same internal dose of chemical was calculated for each test chemical. The calculated ratio in humans ranged from 18 for styrene to 1180 for isoflurane. This methodology can be used to estimate the dermal exposure required to reach the internal dose achieved by a specific inhalation exposure. Such extrapolation is important since allowable exposure standards are often set for inhalation exposures, but occupational exposures may be dermal.

  17. Halogen Bonding: A Powerful Tool for Modulation of Peptide Conformation

    PubMed Central

    2017-01-01

    Halogen bonding is a weak chemical force that has so far mostly found applications in crystal engineering. Despite its potential for use in drug discovery, as a new molecular tool in the direction of molecular recognition events, it has rarely been assessed in biopolymers. Motivated by this fact, we have developed a peptide model system that permits the quantitative evaluation of weak forces in a biologically relevant proteinlike environment and have applied it for the assessment of a halogen bond formed between two amino acid side chains. The influence of a single weak force is measured by detection of the extent to which it modulates the conformation of a cooperatively folding system. We have optimized the amino acid sequence of the model peptide on analogues with a hydrogen bond-forming site as a model for the intramolecular halogen bond to be studied, demonstrating the ability of the technique to provide information about any type of weak secondary interaction. A combined solution nuclear magnetic resonance spectroscopic and computational investigation demonstrates that an interstrand halogen bond is capable of conformational stabilization of a β-hairpin foldamer comparable to an analogous hydrogen bond. This is the first report of incorporation of a conformation-stabilizing halogen bond into a peptide/protein system, and the first quantification of a chlorine-centered halogen bond in a biologically relevant system in solution. PMID:28581720

  18. Reactive and organic halogen species in three different European coastal environments

    NASA Astrophysics Data System (ADS)

    Peters, C.; Pechtl, S.; Stutz, J.; Hebestreit, K.; Hönninger, G.; Heumann, K. G.; Schwarz, A.; Winterlik, J.; Platt, U.

    2005-08-01

    We present results of three field campaigns using active longpath DOAS (Differential Optical Absorption Spectroscopy) for the study of reactive halogen species (RHS) BrO, IO, OIO and I2. Two recent field campaigns took place in Spring 2002 in Dagebüll at the German North Sea Coast and in Spring 2003 in Lilia at the French Atlantic Coast of Brittany. In addition, data from a campaign in Mace Head, Ireland in 1998 was re-evaluated. During these field campaigns volatile halogenated organic compounds (VHOCs) were determined by GC/ECD-ICPMS in air and water. Due to the spatial distribution of macroalgae at the German North Sea Coast we found a clear connection between elevated levels of VHOCs and the appearance of macroalgae. Extraordinarily high concentrations of several VHOCs, especially CH3I and CH3Br of up to 1830 pptv and 875 pptv, respectively, were observed at the coast of Brittany, demonstrating the outstanding level of bioactivity there. We found CH2I2 at levels of up to 20 pptv, and a clear anti-correlation with the appearance of IO. The IO mixing ratio reached up to 7.7±0.5 ppt(pmol/mol) during the day, in reasonable agreement with model studies designed to represent the meteorological and chemical conditions in Brittany. For the two campaigns the DOAS spectra were evaluated for BrO, OIO and I2, but none of these species could be clearly identified (detection limits around 2 ppt, 3 ppt, 20 ppt, resp.). Only in the Mace Head spectra evidence was found for the presence of OIO. Since macroalgae under oxidative stress are suggested to be a further source for I2 in the marine boundary layer, we re-analyzed spectra in the 500-600 nm range taken during the 1998 PARFORCE campaign in Mace Head, Ireland, which had not previously been analyzed for I2. We identified molecular iodine above the detection limit (~20 ppt), with peak concentrations of 61±12 ppt. Since I2 was undetectable during the Brittany campaign, we suggest that iodine may not be released into the

  19. Binding interactions of halogenated bisphenol A with mouse PPARα: In vitro investigation and molecular dynamics simulation.

    PubMed

    Zhang, Jie; Li, Tiezhu; Wang, Tuoyi; Guan, Tianzhu; Yu, Hansong; Li, Zhuolin; Wang, Yongzhi; Wang, Yongjun; Zhang, Tiehua

    2018-02-01

    The binding of bisphenol A (BPA) and its halogenated derivatives (halogenated BPAs) to mouse peroxisome proliferator-activated receptor α ligand binding domain (mPPARα-LBD) was examined by a combination of in vitro investigation and in silico simulation. Fluorescence polarization (FP) assay showed that halogenated BPAs could bind to mPPARα-LBD* as the affinity ligands. The calculated electrostatic potential (ESP) illustrated the different charge distributions of halogenated BPAs with altered halogenation patterns. As electron-attracting substituents, halogens decrease the positive electrostatic potential and thereby have a significant influence on the electrostatic interactions of halogenated BPAs with mPPARα-LBD*. The docking results elucidated that hydrophobic and hydrogen-bonding interactions may also contribute to stabilize the binding of the halogenated BPAs to their receptor molecule. Comparison of the calculated binding energies with the experimentally determined affinities yielded a good correlation (R 2 =0.6659) that could provide a rational basis for designing environmentally benign chemicals with reduced toxicities. This work can potentially be used for preliminary screening of halogenated BPAs. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Halogenation of microcapsule walls

    NASA Technical Reports Server (NTRS)

    Davis, T. R.; Schaab, C. K.; Scott, J. C.

    1972-01-01

    Procedure for halogenation of confining walls of both gelatin and gelatin-phenolic resin capsules is similar to that used for microencapsulation. Ten percent halogen content renders capsule wall nonburning; any higher content enhances flame-retardant properties of selected internal phase material. Halogenation decreases permeability of wall material to encapsulated materials.

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

    PubMed

    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.

  2. NTP Renal Toxicity Studies of Selected Halogenated Ethanes Administered by Gavage to F344/N Rats.

    PubMed

    1996-02-01

    The National Cancer Institute and National Toxicology Program have performed 2-year toxicology and carcinogenesis studies with a number of ethanes substituted with chlorine or bromine. A review of the results of studies with these halogenated ethanes has revealed several consistencies between the pattern of halogen substitution and neoplastic responses in some affected organs. One of these consistencies was the finding of a modest increase in the incidence of renal tubule cell neoplasms in male rats administered penta- or hexachloroethane. Certain aspects of the nephropathy also noted in these studies resembled what is now recognized as a distinct hyaline droplet nephropathy typically associated with the accumulation of alpha[alpha]2&mgr;-globulin in renal tubule cells. In an attempt to determine some of the structure activity relationships involved in the induction of hyaline droplet nephropathy by halogenated ethanes, a series of commercially available ethanes substituted with three or more chlorines, four or more bromines, or a combination of chlorines and fluorines was studied in a short-term renal toxicity assessment in male F344/N rats. All chemicals were administered by gavage in corn oil to groups of five male rats once daily for 21 days. The doses selected for study, 0.62 and 1.24 mmol/kg per day, were based on those used in the 2-year pentachloroethane studies. The following chemicals were evaluated: 1,1,1,2- and 1,1,2,2-tetrachloroethane; pentachloroethane; 1,1,2,2-tetrachloro1,2-difluoroethane; 1,1,1-trichloro-2,2,2-trifluoroethane; 1,2-dichloro-1,1-difluoroethane; 1,1,1-trichloroethane; hexachloroethane; 1,1,1,2-and 1,1,2,2-tetrabromoethane; and pentabromoethane. Evaluations included survival, mean body weight gains, clinical signs, organ weights, urinalysis, and histopathologic examination of the right kidney and liver. The kidneys of rats that showed a difference in renal protein droplet accumulation compared to the controls were evaluated for

  3. ORGANIZATION II, NOVA SCIENCE UNIT 3.

    ERIC Educational Resources Information Center

    Broward County Schools, Fort Lauderdale, FL.

    THE ORGANIZATION OF THE NATURE OF SCIENCE IS EMPHASIZED THROUGH A FOCUS ON CHEMICAL REACTIONS. SIMILARITIES OF THE REACTIONS OF THE HALOGENS WITH THE ALKALI METALS OF LITHIUM, SODIUM, POTASSIUM, AND HYDROGEN ARE INTRODUCED TO THE STUDENT. STUDENTS ARE INTRODUCED TO THE PERIODIC TABLE OF ELEMENTS WHICH EMPHASIZES THE ORGANIZATION OF CHEMICAL…

  4. In situ thermally enhanced biodegradation of petroleum fuel hydrocarbons and halogenated organic solvents

    DOEpatents

    Taylor, Robert T.; Jackson, Kenneth J.; Duba, Alfred G.; Chen, Ching-I

    1998-01-01

    An in situ thermally enhanced microbial remediation strategy and a method for the biodegradation of toxic petroleum fuel hydrocarbon and halogenated organic solvent contaminants. The method utilizes nonpathogenic, thermophilic bacteria for the thermal biodegradation of toxic and carcinogenic contaminants, such as benzene, toluene, ethylbenzene and xylenes, from fuel leaks and the chlorinated ethenes, such as trichloroethylene, chlorinated ethanes, such as 1,1,1-trichloroethane, and chlorinated methanes, such as chloroform, from past solvent cleaning practices. The method relies on and takes advantage of the pre-existing heated conditions and the array of delivery/recovery wells that are created and in place following primary subsurface contaminant volatilization efforts via thermal approaches, such as dynamic underground steam-electrical heating.

  5. The Halogen Bond in the Design of Functional Supramolecular Materials: Recent Advances

    PubMed Central

    2013-01-01

    Halogen bonding is an emerging noncovalent interaction for constructing supramolecular assemblies. Though similar to the more familiar hydrogen bonding, four primary differences between these two interactions make halogen bonding a unique tool for molecular recognition and the design of functional materials. First, halogen bonds tend to be much more directional than (single) hydrogen bonds. Second, the interaction strength scales with the polarizability of the bond-donor atom, a feature that researchers can tune through single-atom mutation. In addition, halogen bonds are hydrophobic whereas hydrogen bonds are hydrophilic. Lastly, the size of the bond-donor atom (halogen) is significantly larger than hydrogen. As a result, halogen bonding provides supramolecular chemists with design tools that cannot be easily met with other types of noncovalent interactions and opens up unprecedented possibilities in the design of smart functional materials. This Account highlights the recent advances in the design of halogen-bond-based functional materials. Each of the unique features of halogen bonding, directionality, tunable interaction strength, hydrophobicity, and large donor atom size, makes a difference. Taking advantage of the hydrophobicity, researchers have designed small-size ion transporters. The large halogen atom size provided a platform for constructing all-organic light-emitting crystals that efficiently generate triplet electrons and have a high phosphorescence quantum yield. The tunable interaction strengths provide tools for understanding light-induced macroscopic motions in photoresponsive azobenzene-containing polymers, and the directionality renders halogen bonding useful in the design on functional supramolecular liquid crystals and gel-phase materials. Although halogen bond based functional materials design is still in its infancy, we foresee a bright future for this field. We expect that materials designed based on halogen bonding could lead to

  6. Chlorinated organic compounds in urban river sediments

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Soma, Y.; Shiraishi, H.; Inaba, K.

    1995-12-31

    Among anthropogenic chemicals, many chlorinated organic compounds have been used as insecticides and detected frequently as contaminants in urban river sediments so far. However, the number and total amount of chemicals produced commercially and used are increasing year by year, though each amount of chemicals is not so high. New types of contaminants in the environment may be detected by the use of newly developed chemicals. Chlorinated organic compounds in the urban river sediments around Tokyo and Kyoto, large cities in Japan, were surveyed and recent trends of contaminants were studied. Contaminants of the river sediments in industrial areas hadmore » a variety, but PCB (polychlorinated biphenyls) was detected in common in industrial areas. Concentration of PCB related well to the number of factories on both sides of rivers, although the use of PCB was stopped 20 years ago. In domestic areas, Triclosan (5-chloro-2-(2,4-dichlorophenoxy)-phenol) and Triclocarban (3,4,4{prime}-trichlorocarbanilide)(both are contained in soap or shampoo for fungicides), p-dichlorobenzene (insecticides for wears) and TCEP(tris-chloroethyl phosphate) were detected. EOX(extracted organic halogen) in the sediments was 5 to 10 times of chlorinated organic compounds detected by GC/MS. Major part of organic halogen was suggested to be included in chlorinated organics formed by bleaching or sterilization.« less

  7. Reactive and organic halogen species in three different European coastal environments

    NASA Astrophysics Data System (ADS)

    Peters, C.; Pechtl, S.; Stutz, J.; Hebestreit, K.; Hönninger, G.; Heumann, K. G.; Schwarz, A.; Winterlik, J.; Platt, U.

    2005-12-01

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

  8. Reactive and Organic Halogen Species in Three Different European Coastal Environments

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

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

  9. Reversible capture and release of Cl 2 and Br 2 with a redox-active metal–organic framework

    DOE PAGES

    Tulchinsky, Yuri; Hendon, Christopher H.; Lomachenko, Kirill A.; ...

    2017-03-28

    Extreme toxicity, corrosiveness, and volatility pose serious challenges for the safe storage and transportation of elemental chlorine and bromine, which play critical roles in the chemical industry. Solid materials capable of forming stable nonvolatile compounds upon reaction with elemental halogens may partially mitigate these challenges by allowing safe halogen release on demand. Here we demonstrate that elemental halogens quantitatively oxidize coordinatively unsaturated Co(II) ions in a robust azolate metal-organic framework (MOF) to produce stable and safe-to-handle Co(III) materials featuring terminal Co(III)-halogen bonds. Thermal treatment of the oxidized MOF causes homolytic cleavage of the Co(III)-halogen bonds, reduction to Co(II), and concomitantmore » release of elemental halogens. The reversible chemical storage and thermal release of elemental halogens occur with no significant losses of structural integrity, as the parent cobaltous MOF retains its crystallinity and porosity even after three oxidation/reduction cycles. Finally, these results highlight a material operating via redox mechanism that may find utility in the storage and capture of other noxious and corrosive gases.« less

  10. Substituent Effects on the [N-I-N](+) Halogen Bond.

    PubMed

    Carlsson, Anna-Carin C; Mehmeti, Krenare; Uhrbom, Martin; Karim, Alavi; Bedin, Michele; Puttreddy, Rakesh; Kleinmaier, Roland; Neverov, Alexei A; Nekoueishahraki, Bijan; Gräfenstein, Jürgen; Rissanen, Kari; Erdélyi, Máté

    2016-08-10

    We have investigated the influence of electron density on the three-center [N-I-N](+) halogen bond. A series of [bis(pyridine)iodine](+) and [1,2-bis((pyridine-2-ylethynyl)benzene)iodine](+) BF4(-) complexes substituted with electron withdrawing and donating functionalities in the para-position of their pyridine nitrogen were synthesized and studied by spectroscopic and computational methods. The systematic change of electron density of the pyridine nitrogens upon alteration of the para-substituent (NO2, CF3, H, F, Me, OMe, NMe2) was confirmed by (15)N NMR and by computation of the natural atomic population and the π electron population of the nitrogen atoms. Formation of the [N-I-N](+) halogen bond resulted in >100 ppm (15)N NMR coordination shifts. Substituent effects on the (15)N NMR chemical shift are governed by the π population rather than the total electron population at the nitrogens. Isotopic perturbation of equilibrium NMR studies along with computation on the DFT level indicate that all studied systems possess static, symmetric [N-I-N](+) halogen bonds, independent of their electron density. This was further confirmed by single crystal X-ray diffraction data of 4-substituted [bis(pyridine)iodine](+) complexes. An increased electron density of the halogen bond acceptor stabilizes the [N···I···N](+) bond, whereas electron deficiency reduces the stability of the complexes, as demonstrated by UV-kinetics and computation. In contrast, the N-I bond length is virtually unaffected by changes of the electron density. The understanding of electronic effects on the [N-X-N](+) halogen bond is expected to provide a useful handle for the modulation of the reactivity of [bis(pyridine)halogen](+)-type synthetic reagents.

  11. Substituent Effects on the [N–I–N]+ Halogen Bond

    PubMed Central

    2016-01-01

    We have investigated the influence of electron density on the three-center [N–I–N]+ halogen bond. A series of [bis(pyridine)iodine]+ and [1,2-bis((pyridine-2-ylethynyl)benzene)iodine]+ BF4– complexes substituted with electron withdrawing and donating functionalities in the para-position of their pyridine nitrogen were synthesized and studied by spectroscopic and computational methods. The systematic change of electron density of the pyridine nitrogens upon alteration of the para-substituent (NO2, CF3, H, F, Me, OMe, NMe2) was confirmed by 15N NMR and by computation of the natural atomic population and the π electron population of the nitrogen atoms. Formation of the [N–I–N]+ halogen bond resulted in >100 ppm 15N NMR coordination shifts. Substituent effects on the 15N NMR chemical shift are governed by the π population rather than the total electron population at the nitrogens. Isotopic perturbation of equilibrium NMR studies along with computation on the DFT level indicate that all studied systems possess static, symmetric [N–I–N]+ halogen bonds, independent of their electron density. This was further confirmed by single crystal X-ray diffraction data of 4-substituted [bis(pyridine)iodine]+ complexes. An increased electron density of the halogen bond acceptor stabilizes the [N···I···N]+ bond, whereas electron deficiency reduces the stability of the complexes, as demonstrated by UV-kinetics and computation. In contrast, the N–I bond length is virtually unaffected by changes of the electron density. The understanding of electronic effects on the [N–X–N]+ halogen bond is expected to provide a useful handle for the modulation of the reactivity of [bis(pyridine)halogen]+-type synthetic reagents. PMID:27265247

  12. Halogenated methyl-phenyl ethers (anisoles) in the environment: determination of vapor pressures, aqueous solubilities, Henry's law constants, and gas/water- (Kgw), n-octanol/water- (Kow) and gas/n-octanol (Kgo) partition coefficients.

    PubMed

    Pfeifer, O; Lohmann, U; Ballschmiter, K

    2001-11-01

    Halogenated methyl-phenyl ethers (methoxybenzenes, anisoles) are ubiquitous organics in the environment although they are not produced in industrial quantities. Modelling the fate of organic pollutants such as halogenated anisoles requires a knowledge of the fundamental physico-chemical properties of these compounds. The isomer-specific separation and detection of 60 of the 134 possible congeners allowing an environmental fingerprinting are reported in this study. The vapor pressure p0(L) of more than 60 and further physico-chemical properties of 26 available congeners are given. Vapor pressures p0(L), water solubilities S(L)W, and n-octanol/water partition coefficients Kow were determined by capillary HR-GC (High Resolution Gas Chromatography) on a non-polar phase and by RP-HPLC (Reversed Phase High Performance Liquid Chromatography) on a C18 phase with chlorobenzenes as reference standards. From these experimental data the Henry's law constants H, and the gas/water Kgw and gas/n-octanol Kgo partition coefficients were calculated. We found that vapor pressures, water solubilities, and n-octanol/water partition coefficients of the halogenated anisoles are close to those of the chlorobenzenes. A similar environmental fate of both groups can, therefore, be predicted.

  13. In situ thermally enhanced biodegradation of petroleum fuel hydrocarbons and halogenated organic solvents

    DOEpatents

    Taylor, R.T.; Jackson, K.J.; Duba, A.G.; Chen, C.I.

    1998-05-19

    An in situ thermally enhanced microbial remediation strategy and a method for the biodegradation of toxic petroleum fuel hydrocarbon and halogenated organic solvent contaminants are described. The method utilizes nonpathogenic, thermophilic bacteria for the thermal biodegradation of toxic and carcinogenic contaminants, such as benzene, toluene, ethylbenzene and xylenes, from fuel leaks and the chlorinated ethenes, such as trichloroethylene, chlorinated ethanes, such as 1,1,1-trichloroethane, and chlorinated methanes, such as chloroform, from past solvent cleaning practices. The method relies on and takes advantage of the pre-existing heated conditions and the array of delivery/recovery wells that are created and in place following primary subsurface contaminant volatilization efforts via thermal approaches, such as dynamic underground steam-electrical heating. 21 figs.

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

    PubMed

    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.

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

    PubMed

    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.

  16. Small-Molecule Organic Photovoltaic Modules Fabricated via Halogen-Free Solvent System with Roll-to-Roll Compatible Scalable Printing Method.

    PubMed

    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).

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

    PubMed

    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.

  18. Volatile organic compound sensor system

    DOEpatents

    Schabron, John F [Laramie, WY; Rovani, Jr., Joseph F.; Bomstad, Theresa M [Laramie, WY; Sorini-Wong, Susan S [Laramie, WY

    2009-02-10

    Generally, this invention relates to the development of field monitoring methodology for new substances and sensing chemical warfare agents (CWAs) and terrorist substances. It also relates to a portable test kit which may be utilized to measure concentrations of halogenated volatile organic compounds (VOCs) in the field. Specifically it relates to systems for reliably field sensing the potential presence of such items while also distinguishing them from other elements potentially present. It also relates to overall systems and processes for sensing, reacting, and responding to an indicated presence of such substance, including modifications of existing halogenated sensors and arrayed sensing systems and methods.

  19. Volatile organic compound sensor system

    DOEpatents

    Schabron, John F.; Rovani, Jr., Joseph F.; Bomstad, Theresa M.; Sorini-Wong, Susan S.; Wong, Gregory K.

    2011-03-01

    Generally, this invention relates to the development of field monitoring methodology for new substances and sensing chemical warfare agents (CWAs) and terrorist substances. It also relates to a portable test kit which may be utilized to measure concentrations of halogenated volatile organic compounds (VOCs) in the field. Specifically it relates to systems for reliably field sensing the potential presence of such items while also distinguishing them from other elements potentially present. It also relates to overall systems and processes for sensing, reacting, and responding to an indicated presence of such substance, including modifications of existing halogenated sensors and arrayed sensing systems and methods.

  20. Designing safer chemicals: predicting the rates of metabolism of halogenated alkanes.

    PubMed

    Yin, H; Anders, M W; Korzekwa, K R; Higgins, L; Thummel, K E; Kharasch, E D; Jones, J P

    1995-11-21

    A computational model is presented that can be used as a tool in the design of safer chemicals. This model predicts the rate of hydrogen-atom abstraction by cytochrome P450 enzymes. Excellent correlations between biotransformation rates and the calculated activation energies (delta Hact) of the cytochrome P450-mediated hydrogen-atom abstractions were obtained for the in vitro biotransformation of six halogenated alkanes (1-fluoro-1,1,2,2-tetrachloroethane, 1,1-difluoro-1,2,2-trichloroethane, 1,1,1-trifluro-2,2-dichloroethane, 1,1,1,2-tetrafluoro-2-chloroethane, 1,1,1,2,2,-pentafluoroethane, and 2-bromo-2-chloro-1,1,1-trifluoroethane) with both rat and human enzyme preparations: In(rate, rat liver microsomes) = 44.99 - 1.79(delta Hact), r2 = 0.86; In(rate, human CYP2E1) = 46.99 - 1.77(delta Hact), r2 = 0.97 (rates are in nmol of product per min per nmol of cytochrome P450 and energies are in kcal/mol). Correlations were also obtained for five inhalation anesthetics (enflurane, sevoflurane, desflurane, methoxyflurane, and isoflurane) for both in vivo and in vitro metabolism by humans: In[F(-)]peak plasma = 42.87 - 1.57(delta Hact), r2 = 0.86. To our knowledge, these are the first in vivo human metabolic rates to be quantitatively predicted. Furthermore, this is one of the first examples where computational predictions and in vivo and in vitro data have been shown to agree in any species. The model presented herein provides an archetype for the methodology that may be used in the future design of safer chemicals, particularly hydrochlorofluorocarbons and inhalation anesthetics.

  1. Designing safer chemicals: predicting the rates of metabolism of halogenated alkanes.

    PubMed Central

    Yin, H; Anders, M W; Korzekwa, K R; Higgins, L; Thummel, K E; Kharasch, E D; Jones, J P

    1995-01-01

    A computational model is presented that can be used as a tool in the design of safer chemicals. This model predicts the rate of hydrogen-atom abstraction by cytochrome P450 enzymes. Excellent correlations between biotransformation rates and the calculated activation energies (delta Hact) of the cytochrome P450-mediated hydrogen-atom abstractions were obtained for the in vitro biotransformation of six halogenated alkanes (1-fluoro-1,1,2,2-tetrachloroethane, 1,1-difluoro-1,2,2-trichloroethane, 1,1,1-trifluro-2,2-dichloroethane, 1,1,1,2-tetrafluoro-2-chloroethane, 1,1,1,2,2,-pentafluoroethane, and 2-bromo-2-chloro-1,1,1-trifluoroethane) with both rat and human enzyme preparations: In(rate, rat liver microsomes) = 44.99 - 1.79(delta Hact), r2 = 0.86; In(rate, human CYP2E1) = 46.99 - 1.77(delta Hact), r2 = 0.97 (rates are in nmol of product per min per nmol of cytochrome P450 and energies are in kcal/mol). Correlations were also obtained for five inhalation anesthetics (enflurane, sevoflurane, desflurane, methoxyflurane, and isoflurane) for both in vivo and in vitro metabolism by humans: In[F(-)]peak plasma = 42.87 - 1.57(delta Hact), r2 = 0.86. To our knowledge, these are the first in vivo human metabolic rates to be quantitatively predicted. Furthermore, this is one of the first examples where computational predictions and in vivo and in vitro data have been shown to agree in any species. The model presented herein provides an archetype for the methodology that may be used in the future design of safer chemicals, particularly hydrochlorofluorocarbons and inhalation anesthetics. PMID:7479940

  2. A Base-Resistant Metalloporphyrin Metal–Organic Framework for C–H Bond Halogenation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lv, Xiu-Liang; Wang, Kecheng; Wang, Bin

    A base-resistant porphyrin metal–organic framework (MOF), namely PCN-602 has been constructed with 12-connected [Ni 8(OH) 4(H 2O) 2Pz 12] (Pz = pyrazolate) cluster and a newly designed pyrazolate-based porphyrin ligand, 5,10,15,20-tetrakis(4-(pyrazolate-4-yl)phenyl)porphyrin under the guidance of the reticular synthesis strategy. Besides its robustness in hydroxide solution, PCN-602 also shows excellent stability in aqueous solutions of F –, CO 3 2–, and PO 4 3– ions. Interestingly, the Mn 3+-porphyrinic PCN-602, as a recyclable MOF catalyst, presents high catalytic activity for the C–H bond halogenation reaction in a basic system, significantly outperforming its homogeneous counterpart. For the first time, a porphyrinic MOFmore » was thus used as an efficient catalyst in a basic solution with coordinating anions, to the best of our knowledge.« less

  3. Evidence for Interfacial Halogen Bonding.

    PubMed

    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.

  4. Tropospheric impacts of volcanic halogen emissions: first simulations of reactive halogen chemistry in the Eyjafjallajökull eruption plume

    NASA Astrophysics Data System (ADS)

    Roberts, Tjarda

    2013-04-01

    Volcanic plumes are regions of high chemical reactivity. Instrumented research aircraft that probed the 2010 Icelandic Eyjafjallajökull eruption plume identified in-plume ozone depletion and reactive halogens (Cl, BrO), the latter also detected by satellite. These measurements add to growing evidence that volcanic plumes support rapid reactive halogen chemistry, with predicted impacts including depletion of atmospheric oxidants and mercury deposition. However, attempts to simulate volcanic plume halogen chemistry and predict impacts are subject to considerable uncertainties. e.g. in rate constants for HOBr reactive uptake (see this session: EGU2013-6076), or in the high-temperature initialisation. Model studies attempting to replicate volcanic plume halogen chemistry are restricted by a paucity of field data that is required both for model tuning and verification, hence reported model 'solutions' are not necessarily unique. To this end, the aircraft, ground-based and satellite studies of the Eyjafjallajökull eruption provide a valuable combination of datasets for improving our understanding of plume chemistry and impacts. Here, PlumeChem simulations of Eyjafjallajökull plume reactive halogen chemistry and impacts are presented and verified by observations for the first time. Observed ozone loss, a function of plume strength and age, is quantitatively reproduced by the model. Magnitudinal agreement to reported downwind BrO and Cl is also shown. The model predicts multi-day impacts, with reactive bromine mainly as BrO, HOBr and BrONO2 during daytime, and Br2 and BrCl at night. BrO/SO2 is reduced in more dispersed plumes due to enhanced partitioning to HOBr, of potential interest to satellite studies of BrO downwind of volcanoes. Additional predicted impacts of Eyjafjallajökull volcanic plume halogen chemistry include BrO-mediated depletion of HOx that reduces the rate of SO2 oxidation to H2SO4, hence the formation of sulphate aerosol. The model predicts NOx is

  5. Halogenated solvent remediation

    DOEpatents

    Sorenson, Jr., Kent S.

    2008-11-11

    Methods for enhancing bioremediation of ground water contaminated with nonaqueous halogenated solvents are disclosed. An illustrative method includes adding an electron donor for microbe-mediated anaerobic reductive dehalogenation of the halogenated solvents, which electron donor enhances mass transfer of the halogenated solvents from residual source areas into the aqueous phase of the ground water. Illustrative electron donors include C.sub.2-C.sub.4 carboxylic acids and hydroxy acids, salts thereof, esters of C.sub.2-C.sub.4 carboxylic acids and hydroxy acids, and mixtures thereof, of which lactic acid, salts of lactic acid--such as sodium lactate, lactate esters, and mixtures thereof are particularly illustrative. The microbes are either indigenous to the ground water, or such microbes can be added to the ground water in addition to the electron donor.

  6. Halogenated boron-dipyrromethenes: synthesis, properties and applications.

    PubMed

    Lakshmi, Vellanki; Rao, Malakalapalli Rajeswara; Ravikanth, Mangalampalli

    2015-03-07

    Boron-dipyrromethene dyes (BODIPYs) containing halogens at pyrrole carbons are very useful synthons for the synthesis of a variety of BOIDPYs for a wide range of applications. Among the functional groups, halogens are the functional groups which can be regiospecifically introduced at any desired pyrrole carbon of the BODIPY framework by adopting appropriate synthetic strategies. The halogenated BODIPYs can undergo facile nucleophilic substitution reactions to prepare several interesting BODIPY based compounds. This review describes the synthesis, properties and potential applications of halogenated BODIPYs containing one to six halogens at the pyrrole carbons of the BODIPY core as well as properties and applications of some of the substituted BODIPYs derived from halogenated BODIPYs.

  7. Halogen bond: a long overlooked interaction.

    PubMed

    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.

  8. Reduction of halogenated ethanes by green rust.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    O'Loughlin, E. J.; Burris, D. R.; Environmental Research

    Green rusts, mixed Fe{sup II}/Fe{sup III} hydroxide minerals present in many suboxic environments, have been shown to reduce a number of organic and inorganic contaminants. The reduction of halogenated ethanes was examined in aqueous suspensions of green rust, both alone and with the addition of Ag{sup I} (AgGR) and Cu{sup II} (CuGR). Hexachloroethane (HCA), pentachloroethane (PCA), 1,1,1,2-tetrachloroethane (1,1,1,2-TeCA), 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA), 1,1,1-trichloroethane (1,1,1-TCA), 1,1,2-trichloroethane (1,1,2-TCA), 1,1-dichloroethane (1,1-DCA), and 1,2-dibromoethane were reduced in the presence of green rust alone, AgGR, or CuGR; only 1,2-dichloroethane and chloroethane were nonreactive. The reduction was generally more rapid for more highly substituted ethanes than for ethanesmore » having fewer halogen groups (HCA > PCA > 1,1,1,2-TeCA > 1,1,1-TCA > 1,1,2,2-TeCA > 1,1,2-TCA > 1,1-DCA), and isomers with the more asymmetric distributions of halogen groups were more rapidly reduced than the isomer with greater symmetry (e.g., 1,1,1-TCA > 1,1,2-TCA). The addition of Ag{sup I} or Cu{sup II} to green rust suspensions resulted in a substantial increase in the rate of halogenated ethane reduction as well as significant differences in the product distributions with respect to green rust alone.« less

  9. Structure-Energy Relationships of Halogen Bonds in Proteins.

    PubMed

    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. Halogen bonding in solution: thermodynamics and applications.

    PubMed

    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.

  11. Chemoselective Hydrodehalogenation of Organic Halides Utilizing Two-Dimensional Anionic Electrons of Inorganic Electride [Ca2N]+·e.

    PubMed

    Kim, Ye Ji; Kim, Sun Min; Yu, Chunghyeon; Yoo, YoungMin; Cho, Eun Jin; Yang, Jung Woon; Kim, Sung Wng

    2017-01-31

    Halogenated organic compounds are important anthropogenic chemicals widely used in chemical industry, biology, and pharmacology; however, the persistence and inertness of organic halides cause human health problems and considerable environmental pollution. Thus, the elimination or replacement of halogen atoms with organic halides has been considered a central task in synthetic chemistry. In dehalogenation reactions, the consecutive single-electron transfer from reducing agents generates the radical and corresponding carbanion and thus removes the halogen atom as the leaving group. Herein, we report a new strategy for an efficient chemoselective hydrodehalogenation through the formation of stable carbanion intermediates, which are simply achieved by using highly mobile two-dimensional electrons of inorganic electride [Ca 2 N] + ·e - with effective electron transfer ability. The consecutive single-electron transfer from inorganic electride [Ca 2 N] + ·e - stabilized free carbanions, which is a key step in achieving the selective reaction. Furthermore, a determinant more important than leaving group ability is the stability control of free carbanions according to the s character determined by the backbone structure. We anticipate that this approach may provide new insight into selective chemical formation, including hydrodehalogenation.

  12. Engineering of new-to-nature halogenated indigo precursors in plants.

    PubMed

    Fräbel, Sabine; Wagner, Bastian; Krischke, Markus; Schmidts, Volker; Thiele, Christina M; Staniek, Agata; Warzecha, Heribert

    2018-03-01

    Plants are versatile chemists producing a tremendous variety of specialized compounds. Here, we describe the engineering of entirely novel metabolic pathways in planta enabling generation of halogenated indigo precursors as non-natural plant products. Indican (indolyl-β-D-glucopyranoside) is a secondary metabolite characteristic of a number of dyers plants. Its deglucosylation and subsequent oxidative dimerization leads to the blue dye, indigo. Halogenated indican derivatives are commonly used as detection reagents in histochemical and molecular biology applications; their production, however, relies largely on chemical synthesis. To attain the de novo biosynthesis in a plant-based system devoid of indican, we employed a sequence of enzymes from diverse sources, including three microbial tryptophan halogenases substituting the amino acid at either C5, C6, or C7 of the indole moiety. Subsequent processing of the halotryptophan by bacterial tryptophanase TnaA in concert with a mutant of the human cytochrome P450 monooxygenase 2A6 and glycosylation of the resulting indoxyl derivatives by an endogenous tobacco glucosyltransferase yielded corresponding haloindican variants in transiently transformed Nicotiana benthamiana plants. Accumulation levels were highest when the 5-halogenase PyrH was utilized, reaching 0.93 ± 0.089 mg/g dry weight of 5-chloroindican. The identity of the latter was unambiguously confirmed by NMR analysis. Moreover, our combinatorial approach, facilitated by the modular assembly capabilities of the GoldenBraid cloning system and inspired by the unique compartmentation of plant cells, afforded testing a number of alternative subcellular localizations for pathway design. In consequence, chloroplasts were validated as functional biosynthetic venues for haloindican, with the requisite reducing augmentation of the halogenases as well as the cytochrome P450 monooxygenase fulfilled by catalytic systems native to the organelle. Thus, our study

  13. Adsorption of halogens on metal surfaces

    NASA Astrophysics Data System (ADS)

    Andryushechkin, B. V.; Pavlova, T. V.; Eltsov, K. N.

    2018-06-01

    This paper presents a review of the experimental and theoretical investigations of halogen interaction with metal surfaces. The emphasis was placed on the recent measurements performed with a scanning tunneling microscope in combination with density functional theory calculations. The surface structures formed on metal surface after halogen interaction are classified into three groups: chemisorbed monolayer, surface halide, bulk-like halide. Formation of monolayer structures is described in terms of surface phase transitions. Surface halide phases are considered to be intermediates between chemisorbed halogen and bulk halide. The modern theoretical approaches in studying the dynamics of metal halogenation reactions are also presented.

  14. Halogenated solvent remediation

    DOEpatents

    Sorenson, Kent S.

    2004-08-31

    Methods for enhancing bioremediation of ground water contaminated with nonaqueous halogenated solvents are disclosed. A preferred method includes adding a composition to the ground water wherein the composition is an electron donor for microbe-mediated reductive dehalogenation of the halogenated solvents and enhances mass transfer of the halogenated solvents from residual source areas into the aqueous phase of the ground water. Illustrative compositions effective in these methods include surfactants such as C.sub.2 -C.sub.4 carboxylic acids and hydroxy acids, salts thereof, esters of C.sub.2 -C.sub.4 carboxylic acids and hydroxy acids, and mixtures thereof. Especially preferred compositions for use in these methods include lactic acid, salts of lactic acid, such as sodium lactate, lactate esters, and mixtures thereof. The microbes are either indigenous to the ground water, or such microbes can be added to the ground water in addition to the composition.

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

    USGS Publications Warehouse

    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.

  16. Halogenated arsenenes as Dirac materials

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

    2015-09-01

    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.

  18. Volatile halogenated hydrocarbons in foods

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Miyahara, Makoto; Toyoda, Masatake; Saito, Yukio

    1995-02-01

    Volatile halogenated organic compounds were determined in foods. Statistical treatment of the data for 13 sampled from 20 families living in suburban Tokyo (Saitama prefecture) indicated that the foods were contaminated by water pollution and/or substances introduced by the process of food production. Butter and margarine were contaminated by chlorinated ethylene, ethane, and related compounds released by dry cleaning and other operations. Soybean sprouts and tofu (soybean curd) contained chloroform and related trihalomethanes absorbed during the production process. 27 refs., 6 figs., 5 tabs.

  19. Generation of dissolved organic matter and byproducts from activated sludge during contact with sodium hypochlorite and its implications to on-line chemical cleaning in MBR.

    PubMed

    Cai, Weiwei; Liu, Jiaqi; Zhang, Xiangru; Ng, Wun Jern; Liu, Yu

    2016-11-01

    On-line chemical cleaning of membranes with sodium hypochlorite (NaClO) has been commonly employed for maintaining a constant permeability of membrane bioreactor (MBR) due to its simple and efficient operation. However, activated sludge is inevitably exposed to NaClO during this cleaning process. In spite of the broad applications of on-line chemical cleaning in MBR such as chemical cleaning-in-place (CIP) and chemical enhanced backwash (CEB), little information is currently available for the release of emerging dissolved organic matter (DOM) and byproducts from this prevalent practice. Therefore, in this study, activated sludge suspended in a phosphate buffered saline solution was exposed to different doses of NaClO in order to determine the generation of potential DOM and byproducts. The results showed the occurrence of significant DOM release (up to 24.7 mg/L as dissolved organic carbon) after exposure to NaClO for 30 min. The dominant components of the released DOM were characterized to be humic acid-like as well as protein-like substances by using an excitation-emission matrix fluorescence spectrophotometer. Furthermore, after the contact of activated sludge with NaClO, 19 kinds of chlorinated and brominated byproducts were identified by ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry, eight of which were confirmed and characterized with standard compounds. Many byproducts were found to be halogenated aromatic compounds, including halopyrroles and halo(hydro)benzoquinones, which had been reported to be significantly more toxic than the halogenated aliphatic ones. Consequently, this study offers new insights into the practice of on-line chemical cleaning, and opens up a window to re-examine the current operation of MBR by looking into the generation of micropollutants. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Metal halogen battery construction with improved technique for producing halogen hydrate

    DOEpatents

    Fong, Walter L.; Catherino, Henry A.; Kotch, Richard J.

    1983-01-01

    An improved electrical energy storage system comprising, at least one cell having a positive electrode and a negative electrode separated by aqueous electrolyte, a store means wherein halogen hydrate is formed and stored as part of an aqueous material having a liquid level near the upper part of the store, means for circulating electrolyte through the cell, conduit means for transmitting halogen gas formed in the cell to a hydrate forming apparatus associated with the store, said hydrate forming apparatus including, a pump to which there is introduced quantities of the halogen gas and chilled water, said pump being located in the store and an outlet conduit leading from the pump and being substantially straight and generally vertically disposed and having an exit discharge into the gas space above the liquid level in the store, and wherein said hydrate forming apparatus is highly efficient and very resistant to plugging or jamming. The disclosure also relates to an improved method for producing chlorine hydrate in zinc chlorine batteries.

  1. Activated persulfate for organic chemical degradation: A review.

    PubMed

    Matzek, Laura W; Carter, Kimberly E

    2016-05-01

    Activated persulfate reactions have widespread application for groundwater and environmental remediation, as many of these reactions involve destruction of environmental contaminants. Within the last five years, knowledge of activated persulfate degradation reactions has grown to include novel means of activating persulfate for enhanced removal of organic species. These current studies cover a long list of organic analytes, including pharmaceuticals, pesticides, halogenated compounds and dyes. An extensive review of recently published experimental parameters and results for the destruction of organic compounds via activated persulfate is presented. Focus is placed on emerging methodologies and manipulation of traditional activation techniques. Knowledge gaps are identified and discussed, as despite the number of publications on this subject, more broad-reaching guidelines are needed for optimizing applications of activated persulfate in water treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Halogenated compounds from marine algae.

    PubMed

    Cabrita, Maria Teresa; Vale, Carlos; Rauter, Amélia Pilar

    2010-08-09

    Marine algae produce a cocktail of halogenated metabolites with potential commercial value. Structures exhibited by these compounds go from acyclic entities with a linear chain to complex polycyclic molecules. Their medical and pharmaceutical application has been investigated for a few decades, however other properties, such as antifouling, are not to be discarded. Many compounds were discovered in the last years, although the need for new drugs keeps this field open as many algal species are poorly screened. The ecological role of marine algal halogenated metabolites has somehow been overlooked. This new research field will provide valuable and novel insight into the marine ecosystem dynamics as well as a new approach to comprehending biodiversity. Furthermore, understanding interactions between halogenated compound production by algae and the environment, including anthropogenic or global climate changes, is a challenging target for the coming years. Research of halogenated metabolites has been more focused on macroalgae than on phytoplankton. However, phytoplankton could be a very promising material since it is the base of the marine food chain with quick adaptation to environmental changes, which undoubtedly has consequences on secondary metabolism. This paper reviews recent progress on this field and presents trends on the role of marine algae as producers of halogenated compounds.

  3. Halogenated Compounds from Marine Algae

    PubMed Central

    Cabrita, Maria Teresa; Vale, Carlos; Rauter, Amélia Pilar

    2010-01-01

    Marine algae produce a cocktail of halogenated metabolites with potential commercial value. Structures exhibited by these compounds go from acyclic entities with a linear chain to complex polycyclic molecules. Their medical and pharmaceutical application has been investigated for a few decades, however other properties, such as antifouling, are not to be discarded. Many compounds were discovered in the last years, although the need for new drugs keeps this field open as many algal species are poorly screened. The ecological role of marine algal halogenated metabolites has somehow been overlooked. This new research field will provide valuable and novel insight into the marine ecosystem dynamics as well as a new approach to comprehending biodiversity. Furthermore, understanding interactions between halogenated compound production by algae and the environment, including anthropogenic or global climate changes, is a challenging target for the coming years. Research of halogenated metabolites has been more focused on macroalgae than on phytoplankton. However, phytoplankton could be a very promising material since it is the base of the marine food chain with quick adaptation to environmental changes, which undoubtedly has consequences on secondary metabolism. This paper reviews recent progress on this field and presents trends on the role of marine algae as producers of halogenated compounds. PMID:20948909

  4. Independent Evolution of Six Families of Halogenating Enzymes.

    PubMed

    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.

  5. Independent Evolution of Six Families of Halogenating Enzymes

    PubMed Central

    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. PMID:27153321

  6. Virucidal properties of metal oxide nanoparticles and their halogen adducts.

    PubMed

    Häggström, Johanna; Balyozova, Denitza; Klabunde, Kenneth J; Marchin, George

    2010-04-01

    Selected metal oxide nanoparticles are capable of strongly adsorbing large amounts of halogens (Cl(2), Br, I(2)) and mixed halogens. These solid adducts are relatively stable thermally, and they can be stored for long periods. However, in the open environment, they are potent biocides. Herein are described studies with a number of bacteriophage MS2, phiX174, and PRD-1 (virus examples). PRD-1 is generally more resistant to chemical disinfection, but in this paper it is shown to be very susceptible to selected interhalogen and iodine adducts of CeO(2), Al(2)O(3), and TiO(2) nanoparticles. Overall, the halogen adducts of TiO(2) and Al(2)O(3) were most effective. The mechanism of disinfection by these nanoparticles is not completely clear, but could include abrasive properties, as well as oxidative powers. A hypothesis that nanoparticles damage virons or stick to them and prevent binding to the host cell is a consideration that needs to be explored. Herein are reported comparative biocidal activities of a series of adducts and electron microscope images of before and after treatment.

  7. Identification of specific organic contaminants in different units of a chemical production site.

    PubMed

    Dsikowitzky, L; Botalova, O; al Sandouk-Lincke, N A; Schwarzbauer, J

    2014-07-01

    Due to the very limited number of studies dealing with the chemical composition of industrial wastewaters, many industrial organic contaminants still escape our view and consequently also our control. We present here the chemical characterization of wastewaters from different units of a chemical complex, thereby contributing to the characterization of industrial pollution sources. The chemicals produced in the investigated complex are widely and intensively used and the synthesis processes are common and applied worldwide. The chemical composition of untreated and treated wastewaters from the chemical complex was investigated by applying a non-target screening which allowed for the identification of 39 organic contaminants. According to their application most of them belonged to four groups: (i) unspecific educts or intermediates of industrial syntheses, (ii) chemicals for the manufacturing of pharmaceuticals, (iii) educts for the synthesis of polymers and resins, and (iv) compounds known as typical constituents of municipal sewage. A number of halogenated compounds with unknown toxicity and with very high molecular diversity belonged to the second group. Although these compounds were completely removed or degraded during wastewater treatment, they could be useful as "alarm indicators" for industrial accidents in pharmaceutical manufacturing units or for malfunctions of wastewater treatment plants. Three potential branch-specific indicators for polymer manufacturing were found in the outflow of the complex. Among all compounds, bisphenol A, which was present in the leachate water of the on-site waste deposit, occurred in the highest concentrations of up to 20 000 μg L(-1). The comparison of contaminant loads in the inflow and outflow of the on-site wastewater treatment facility showed that most contaminants were completely or at least significantly removed or degraded during the treatment, except two alkylthiols, which were enriched during the treatment process

  8. REDUCTIVE DEHALOGENATION OF ORGANIC CONTAMINANTS IN SOILS AND GROUND WATER

    EPA Science Inventory

    Introduction and large scale production of synthetic halogenated organic chemicals over the last 50 years has resulted in a group of contaminants which tend to persist in the environment and resist both biotic and abiotic degradation. The low solubility of these types of contamin...

  9. REDUCTIVE DEHALOGENATION OF ORGANIC CONTAMINANTS IN SOILS AND GROUND WATER

    EPA Science Inventory

    Introduction and large-scale production of synthetic halogenated organic chemicals over the last fifty years has resulted in a group of contaminants that tend to persist in the environment and resist both biotic and abiotic degradation. The low solubility of these types of contam...

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

    PubMed

    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.

  11. Use of integrated indoor concentrations of tracer gases and volatile organic compounds to distinguish soil sources from above-ground sources

    EPA Science Inventory

    Vapor intrusion refers to the situation in which harmful chemicals [such as halogenated or chlorinated volatile organic compounds (VOC) or petroleum products] in the groundwater or soil volatilize in the vadose zone and migrate into the indoor environment. These chemicals typical...

  12. Laboratory Investigations of Stratospheric Halogen Chemistry

    NASA Technical Reports Server (NTRS)

    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.

  13. Zebrafish Whole-Adult-Organism Chemogenomics for Large-Scale Predictive and Discovery Chemical Biology

    PubMed Central

    Lam, Siew Hong; Mathavan, Sinnakarupan; Tong, Yan; Li, Haixia; Karuturi, R. Krishna Murthy; Wu, Yilian; Vega, Vinsensius B.; Liu, Edison T.; Gong, Zhiyuan

    2008-01-01

    The ability to perform large-scale, expression-based chemogenomics on whole adult organisms, as in invertebrate models (worm and fly), is highly desirable for a vertebrate model but its feasibility and potential has not been demonstrated. We performed expression-based chemogenomics on the whole adult organism of a vertebrate model, the zebrafish, and demonstrated its potential for large-scale predictive and discovery chemical biology. Focusing on two classes of compounds with wide implications to human health, polycyclic (halogenated) aromatic hydrocarbons [P(H)AHs] and estrogenic compounds (ECs), we generated robust prediction models that can discriminate compounds of the same class from those of different classes in two large independent experiments. The robust expression signatures led to the identification of biomarkers for potent aryl hydrocarbon receptor (AHR) and estrogen receptor (ER) agonists, respectively, and were validated in multiple targeted tissues. Knowledge-based data mining of human homologs of zebrafish genes revealed highly conserved chemical-induced biological responses/effects, health risks, and novel biological insights associated with AHR and ER that could be inferred to humans. Thus, our study presents an effective, high-throughput strategy of capturing molecular snapshots of chemical-induced biological states of a whole adult vertebrate that provides information on biomarkers of effects, deregulated signaling pathways, and possible affected biological functions, perturbed physiological systems, and increased health risks. These findings place zebrafish in a strategic position to bridge the wide gap between cell-based and rodent models in chemogenomics research and applications, especially in preclinical drug discovery and toxicology. PMID:18618001

  14. Organic chemical evolution

    NASA Technical Reports Server (NTRS)

    Chang, S.

    1981-01-01

    The course of organic chemical evolution preceding the emergence of life on earth is discussed based on evidence of processes occurring in interstellar space, the solar system and the primitive earth. Following a brief review of the equilibrium condensation model for the origin and evolution of the solar system, consideration is given to the nature and organic chemistry of interstellar clouds, comets, Jupiter, meteorites, Venus and Mars, and the prebiotic earth. Major issues to be resolved in the study of organic chemical evolution on earth are identified regarding condensation and accretion in the solar nebula, early geological evolution, the origin and evolution of the atmosphere, organic production rates, organic-inorganic interactions, environmental fluctuations, phase separation and molecular selectivity.

  15. Iodine(III) Derivatives as Halogen Bonding Organocatalysts.

    PubMed

    Heinen, Flemming; Engelage, Elric; Dreger, Alexander; Weiss, Robert; Huber, Stefan M

    2018-03-26

    Hypervalent iodine(III) derivatives are known as versatile reagents in organic synthesis, but there is only one previous report on their use as Lewis acidic organocatalysts. Herein, we present first strong indications for the crucial role of halogen bonding in this kind of catalyses. To this end, the solvolysis of benzhydryl chloride and the Diels-Alder reaction of cyclopentadiene with methyl vinyl ketone served as benchmark reactions for halide abstraction and the activation of neutral compounds. Iodolium compounds (cyclic diaryl iodonium species) were used as activators or catalysts, and we were able to markedly reduce or completely switch off their activity by sterically blocking one or two of their electrophilic axes. Compared with previously established bidentate cationic halogen bond donors, the monodentate organoiodine derivatives used herein are at least similarly active (in the Diels-Alder reaction) or even decidedly more active (in benzhydryl chloride solvolysis). © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Treatment System for Removing Halogenated Compounds from Contaminated Sources

    NASA Technical Reports Server (NTRS)

    Clausen, Christian A. (Inventor); Yestrebsky, Cherie L. (Inventor); Quinn, Jacqueline W. (Inventor)

    2015-01-01

    A treatment system and a method for removal of at least one halogenated compound, such as PCBs, found in contaminated systems are provided. The treatment system includes a polymer blanket for receiving at least one non-polar solvent. The halogenated compound permeates into or through a wall of the polymer blanket where it is solubilized with at least one non-polar solvent received by said polymer blanket forming a halogenated solvent mixture. This treatment system and method provides for the in situ removal of halogenated compounds from the contaminated system. In one embodiment, the halogenated solvent mixture is subjected to subsequent processes which destroy and/or degrade the halogenated compound.

  17. Passivation of quartz for halogen-containing light sources

    DOEpatents

    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.

  18. 40 CFR 721.329 - Halogenated benzyl ester acrylate (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... halogenated benzyl ester acrylate (PMN P-90-1527) is subject to reporting under this section for the... substance may cause internal organ effects (kidney and blood). The requirements of this section do not apply... processors of this substance as specified in § 721.125 (a), (b), (c), (d), (f), (g), (h), and (i). (2...

  19. METHOD FOR PRODUCING ISOTOPIC METHANES AND PARTIALLY HALOGENATED DERIVATIVES THEROF

    DOEpatents

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Typical halogenated persistent organic pollutants in indoor dust and the associations with childhood asthma in Shanghai, China.

    PubMed

    Meng, Ge; Nie, Zhiqing; Feng, Yan; Wu, Xiaomeng; Yin, Yong; Wang, Yan

    2016-04-01

    Halogenated persistent organic pollutants (Hal-POPs) are significant contaminants in the indoor environment that are related to many human diseases. Ingestion of indoor dust is considered the major pathway of Hal-POP exposures, especially for children aged 3-6 years. Alongside a retrospective study on the associations between typical Hal-POP exposure and childhood asthma in Shanghai, indoor dust samples from asthmatic and non-asthmatic children's homes (n = 60, each) were collected. Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were measured by GC-MS. BDE-209, PCB-8 and p,p'-DDE were the predominant components in each chemical category. The concentrations of most Hal-POPs were significantly higher in the asthmatic families. The associations between Hal-POP exposure and asthma occurrence were examined by calculating the odds ratios (ORs) using a logistic regression model. A positive association was found between p,p'-DDE in indoor dust and childhood asthma (OR = 1.825, 95%CI: 1.004, 3.317; p = 0.048). The average daily doses of Hal-POP intake were calculated using the method provided by the USEPA. Non-carcinogenic health risks were preliminarily assessed. Our study indicated that exposure to p,p'-DDE via indoor dust may contribute to childhood asthma occurrence. Non-carcinogenic health risks were not found with the intake of Hal-POPs via the ingestion of indoor dust. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Large Plasmids from Soil Bacteria Enriched on Halogenated Alkanoic Acids

    PubMed Central

    Hardman, David J.; Gowland, Peter C.; Slater, J. Howard

    1986-01-01

    Four Pseudomonas species and two Alcaligenes species were isolated from soil with a capacity to grow on halogenated alkanoic acids. They were shown to contain one of five large plasmids. The plasmids had molecular weights ranging from 98,800 to 190,000. They were associated with the ability to utilize the halogenated substrates 2-monochloropropionic acid and 2-monochloroacetic acid and with resistance towards one or more of the heavy metals mercury, selenium, and tellurium. The largest plasmid, pUU204, was shown to be unstable in continuous-flow culture when the organism was supplied with succinate as the sole carbon source. The dehalogenase gene associated with pUU204 appeared to be readily transferred to an incP group plasmid, R68-45. PMID:16346975

  3. Inhibition of thyroid hormone sulfotransferase activity by brominated flame retardants and halogenated phenolics

    PubMed Central

    Butt, Craig M.; Stapleton, Heather M.

    2013-01-01

    Many halogenated organic contaminants (HOCs) are considered endocrine disruptors and affect the hypothalamic-pituitary-thyroid axis, often by interfering with circulating levels of thyroid hormones (THs). This study investigated one potential mechanism for TH disruption, inhibition of sulfotransferase activity. One of the primary roles of TH sulfation is to support the regulation of biologically active T3 through the formation of inactive THs. This study investigated TH sulfotransferase inhibition by 14 hydroxylated polybrominated diphenyl ethers (OH-BDEs), BDE 47, triclosan, and fluorinated, chlorinated, brominated and iodinated analogues of 2,4,6-trihalogenated phenol and BPA. A new mass spectrometry-based method was also developed to measure the formation rates of 3,3′-T2 sulfate (3,3′-T2S). Using pooled human liver cytosol we investigated the influence of these HOCs on the sulfation of 3,3′-T2, a major substrate for TH sulfation. For the formation of 3,3′-T2 sulfate, the Michaelis constant (Km) was 1070 ± 120 nM and the Vmax was 153 ± 6.6 pmol/min.mg protein. All chemicals investigated inhibited sulfotransferase activity with the exception of BDE 47. The 2,4,6-trihalogenated phenols were the most potent inhibitors followed by the OH-BDEs and then halogenated BPAs. The IC50 concentrations for the OH-BDEs were primarily in the low nM range, which may be environmentally relevant. In silico molecular modeling techniques were also used to simulate OH-BDE binding with SULT1A1. This study suggests that some HOCs, including anti-microbial chemicals and metabolites of flame retardants, may interfere with TH regulation through inhibition of sulfotransferase activity. PMID:24089703

  4. Rapid chemical evolution of tropospheric volcanic emissions from Redoubt Volcano, Alaska, based on observations of ozone and halogen-containing gases

    NASA Astrophysics Data System (ADS)

    Kelly, Peter J.; Kern, Christoph; Roberts, Tjarda J.; Lopez, Taryn; Werner, Cynthia; Aiuppa, Alessandro

    2013-06-01

    We report results from an observational and modeling study of reactive chemistry in the tropospheric plume emitted by Redoubt Volcano, Alaska. Our measurements include the first observations of Br and I degassing from an Alaskan volcano, the first study of O3 evolution in a volcanic plume, as well as the first detection of BrO in the plume of a passively degassing Alaskan volcano. This study also represents the first detailed spatially-resolved comparison of measured and modeled O3 depletion in a volcanic plume. The composition of the plume was measured on June 20, 2010 using base-treated filter packs (for F, Cl, Br, I, and S) at the crater rim and by an instrumented fixed-wing aircraft on June 21 and August 19, 2010. The aircraft was used to track the chemical evolution of the plume up to ~ 30 km downwind (2 h plume travel time) from the volcano and was equipped to make in situ observations of O3, water vapor, CO2, SO2, and H2S during both flights plus remote spectroscopic observations of SO2 and BrO on the August 19th flight. The airborne data from June 21 reveal rapid chemical O3 destruction in the plume as well as the strong influence chemical heterogeneity in background air had on plume composition. Spectroscopic retrievals from airborne traverses made under the plume on August 19 show that BrO was present ~ 6 km downwind (20 min plume travel time) and in situ measurements revealed several ppbv of O3 loss near the center of the plume at a similar location downwind. Simulations with the PlumeChem model reproduce the timing and magnitude of the observed O3 deficits and suggest that autocatalytic release of reactive bromine and in-plume formation of BrO were primarily responsible for the observed O3 destruction in the plume. The measurements are therefore in general agreement with recent model studies of reactive halogen formation in volcanic plumes, but also show that field studies must pay close attention to variations in the composition of ambient air

  5. Rapid chemical evolution of tropospheric volcanic emissions from Redoubt Volcano, Alaska, based on observations of ozone and halogen-containing gases

    USGS Publications Warehouse

    Werner, Cynthia A.; Kelly, Peter; Kern, Christoph; Roberts, T.J.; Aluppe, A.

    2013-01-01

    We report results from an observational and modeling study of reactive chemistry in the tropospheric plume emitted by Redoubt Volcano, Alaska. Our measurements include the first observations of Br and I degassing from an Alaskan volcano, the first study of O3 evolution in a volcanic plume, as well as the first detection of BrO in the plume of a passively degassing Alaskan volcano. This study also represents the first detailed spatially-resolved comparison of measured and modeled O3 depletion in a volcanic plume. The composition of the plume was measured on June 20, 2010 using base-treated filter packs (for F, Cl, Br, I, and S) at the crater rim and by an instrumented fixed-wing aircraft on June 21 and August 19, 2010. The aircraft was used to track the chemical evolution of the plume up to ~ 30 km downwind (2 h plume travel time) from the volcano and was equipped to make in situ observations of O3, water vapor, CO2, SO2, and H2S during both flights plus remote spectroscopic observations of SO2 and BrO on the August 19th flight. The airborne data from June 21 reveal rapid chemical O3 destruction in the plume as well as the strong influence chemical heterogeneity in background air had on plume composition. Spectroscopic retrievals from airborne traverses made under the plume on August 19 show that BrO was present ~ 6 km downwind (20 min plume travel time) and in situ measurements revealed several ppbv of O3 loss near the center of the plume at a similar location downwind. Simulations with the PlumeChem model reproduce the timing and magnitude of the observed O3 deficits and suggest that autocatalytic release of reactive bromine and in-plume formation of BrO were primarily responsible for the observed O3 destruction in the plume. The measurements are therefore in general agreement with recent model studies of reactive halogen formation in volcanic plumes, but also show that field studies must pay close attention to variations in the composition of

  6. Magnesium Bisamide-Mediated Halogen Dance of Bromothiophenes.

    PubMed

    Yamane, Yoshiki; Sunahara, Kazuhiro; Okano, Kentaro; Mori, Atsunori

    2018-03-16

    A magnesium bisamide-mediated halogen dance of bromothiophenes is described. The thienylmagnesium species generated in situ is more stable than the corresponding thienyllithium species, which was applied to trap the transient anion species with several electrophiles, such as allyl iodide, phenyl isocyanate, and tributylstannyl chloride. The utility of the magnesium bisamide-mediated halogen dance is useful in the concise synthesis of a medicinally advantageous compound via a one-pot, ester-directed halogen dance/Negishi cross coupling.

  7. Hydrogen bond and halogen bond inside the carbon nanotube

    NASA Astrophysics Data System (ADS)

    Wang, Weizhou; Wang, Donglai; Zhang, Yu; Ji, Baoming; Tian, Anmin

    2011-02-01

    The hydrogen bond and halogen bond inside the open-ended single-walled carbon nanotubes have been investigated theoretically employing the newly developed density functional M06 with the suitable basis set and the natural bond orbital analysis. Comparing with the hydrogen or halogen bond in the gas phase, we find that the strength of the hydrogen or halogen bond inside the carbon nanotube will become weaker if there is a larger intramolecular electron-density transfer from the electron-rich region of the hydrogen or halogen atom donor to the antibonding orbital of the X-H or X-Hal bond involved in the formation of the hydrogen or halogen bond and will become stronger if there is a larger intermolecular electron-density transfer from the electron-rich region of the hydrogen or halogen atom acceptor to the antibonding orbital of the X-H or X-Hal bond. According to the analysis of the molecular electrostatic potential of the carbon nanotube, the driving force for the electron-density transfer is found to be the negative electric field formed in the carbon nanotube inner phase. Our results also show that the X-H bond involved in the formation of the hydrogen bond and the X-Hal bond involved in the formation of the halogen bond are all elongated when encapsulating the hydrogen bond and halogen bond within the carbon nanotube, so the carbon nanotube confinement may change the blue-shifting hydrogen bond and the blue-shifting halogen bond into the red-shifting hydrogen bond and the red-shifting halogen bond. The possibility to replace the all electron nanotube-confined calculation by the simple polarizable continuum model is also evaluated.

  8. Effects of thermal treatment on halogenated disinfection by-products in drinking water.

    PubMed

    Wu, W W; Benjamin, M M; Korshin, G V

    2001-10-01

    The influence of heating or boiling on the formation and behavior of disinfection by-products (DBPs) was investigated in DBP-spiked reagent water, municipal tap water, and synthetic water containing chlorinated aquatic humic substances. Thermal cleavage of larger halogenated species leads to both formation of smaller chlorinated molecules (including THMs and HAAs) and dechlorination of organics. In parallel with their formation from larger molecules, THMs can be volatilized, and this latter process dominates the change in their concentration when water is boiled. HAAs are not volatile, but they can be destroyed by chemical reactions at elevated temperatures, with the net effect being loss of trihalogenated HAAs and either formation or loss of less chlorinated HAAs. Although other identifiable DBPs can be generated at slightly elevated temperatures, in most cases their concentrations decline dramatically when the solution is heated.

  9. The Halogens. Independent Learning Project for Advanced Chemistry (ILPAC). Unit I2.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit, which consists of two levels, focuses on the elements and compounds of Group IV (halogens) of the periodic table. Level one deals with the physical and chemical properties of the individual elements. Level two considers…

  10. Effects of halide ions on photodegradation of sulfonamide antibiotics: Formation of halogenated intermediates.

    PubMed

    Li, Yingjie; Qiao, Xianliang; Zhang, Ya-Nan; Zhou, Chengzhi; Xie, Huaijun; Chen, Jingwen

    2016-10-01

    The occurrence of sulfonamide antibiotics (SAs) in estuarine waters urges insights into their environmental fate for ecological risk assessment. Although many studies focused on the photochemical behavior of SAs, yet the effects of halide ions relevant to estuarine and marine environments on their photodegradation have been poorly understood. Here, we investigated the effects of halide ions on the photodegradation of SAs with sulfapyridine, sulfamethazine, and sulfamethoxazole as representative compounds. Results showed that halide ions did not significantly impact the photodegradation of sulfapyridine and sulfamethoxazole, while they significantly promoted the photodegradation of sulfamethazine. Further experiments found that ionic strength applied with NaClO4 significantly enhanced the photodegradation of the SAs, which was attributed to the decreased quenching rate constant of the triplet-excited SAs ((3)SA(∗)). Compared with ionic strength, specific Cl(-) effects retarded the photodegradation of the SAs. Our study found that triplet-excited sulfamethazine can oxidize halide ions to produce halogen radicals, subsequently leading to the halogenation of sulfamethazine, which was confirmed by the identification of both chlorinated and brominated intermediates. These results indicate that halide ions play an important role in the photochemical behavior of some SAs in estuarine waters and seawater. The occurrence of halogenation for certain organic pollutants can be predicted by comparing the oxidation potentials of triplet-excited contaminants with those of halogen radicals. Our findings are helpful in understanding the photochemical behavior and assessing the ecological risks of SAs and other organic pollutants in estuarine and marine environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    PubMed

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

    2018-06-20

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

  12. C–H bond halogenation catalyzed or mediated by copper: an overview

    PubMed Central

    Hao, Wenyan

    2015-01-01

    Summary Carbon–halogen (C–X) bonds are amongst the most fundamental groups in organic synthesis, they are frequently and widely employed in the synthesis of numerous organic products. The generation of a C–X bond, therefore, constitutes an issue of universal interest. Herein, the research advances on the copper-catalyzed and mediated C–X (X = F, Cl, Br, I) bond formation via direct C–H bond transformation is reviewed. PMID:26664634

  13. Optimization of on-line hydrogen stable isotope ratio measurements of halogen- and sulfur-bearing organic compounds using elemental analyzer-chromium/high-temperature conversion isotope ratio mass spectrometry (EA-Cr/HTC-IRMS).

    PubMed

    Gehre, Matthias; Renpenning, Julian; Geilmann, Heike; Qi, Haiping; Coplen, Tyler B; Kümmel, Steffen; Ivdra, Natalija; Brand, Willi A; Schimmelmann, Arndt

    2017-03-30

    Accurate hydrogen isotopic analysis of halogen- and sulfur-bearing organics has not been possible with traditional high-temperature conversion (HTC) because the formation of hydrogen-bearing reaction products other than molecular hydrogen (H 2 ) is responsible for non-quantitative H 2 yields and possible hydrogen isotopic fractionation. Our previously introduced, new chromium-based EA-Cr/HTC-IRMS (Elemental Analyzer-Chromium/High-Temperature Conversion Isotope Ratio Mass Spectrometry) technique focused primarily on nitrogen-bearing compounds. Several technical and analytical issues concerning halogen- and sulfur-bearing samples, however, remained unresolved and required further refinement of the reactor systems. The EA-Cr/HTC reactor was substantially modified for the conversion of halogen- and sulfur-bearing samples. The performance of the novel conversion setup for solid and liquid samples was monitored and optimized using a simultaneously operating dual-detection system of IRMS and ion trap MS. The method with several variants in the reactor, including the addition of manganese metal chips, was evaluated in three laboratories using EA-Cr/HTC-IRMS (on-line method) and compared with traditional uranium-reduction-based conversion combined with manual dual-inlet IRMS analysis (off-line method) in one laboratory. The modified EA-Cr/HTC reactor setup showed an overall H 2 -recovery of more than 96% for all halogen- and sulfur-bearing organic compounds. All results were successfully normalized via two-point calibration with VSMOW-SLAP reference waters. Precise and accurate hydrogen isotopic analysis was achieved for a variety of organics containing F-, Cl-, Br-, I-, and S-bearing heteroelements. The robust nature of the on-line EA-Cr/HTC technique was demonstrated by a series of 196 consecutive measurements with a single reactor filling. The optimized EA-Cr/HTC reactor design can be implemented in existing analytical equipment using commercially available material and

  14. A survey of chemicals inducing lipid peroxidation in biological systems.

    PubMed

    Kappus, H

    1987-01-01

    A great number of drugs and chemicals are reviewed which have been shown to stimulate lipid peroxidation in any biological system. The underlying mechanisms, as far as known, are also dealt with. Lipid peroxidation induced by iron ions, organic hydroperoxides, halogenated hydrocarbons, redox cycling drugs, glutathione depleting chemicals, ethanol, heavy metals, ozone, nitrogen dioxide and a number of miscellaneous compounds, e.g. hydrazines, pesticides, antibiotics, are mentioned. It is shown that lipid peroxidation is stimulated by many of these compounds. However, quantitative estimates cannot be given yet and it is still impossible to judge the biological relevance of chemical-induced lipid peroxidation.

  15. Halogenated Bisphenol-A Analogs Act as Obesogens in Zebrafish Larvae (Danio rerio)

    PubMed Central

    Pinto, Caroline L.; Grimaldi, Marina; Hillenweck, Anne; Perdu, Elisabeth; Zalko, Daniel; Bernard, Laure; Laudet, Vincent; Balaguer, Patrick; Bondesson, Maria; Gustafsson, Jan-Ake

    2014-01-01

    Obesity has increased dramatically over the past decades, reaching epidemic proportions. The reasons are likely multifactorial. One of the suggested causes is the accelerated exposure to obesity-inducing chemicals (obesogens). However, out of the tens of thousands of industrial chemicals humans are exposed to, very few have been tested for their obesogenic potential, mostly due to the limited availability of appropriate in vivo screening models. In this study, we investigated whether two commonly used flame retardants, the halogenated bisphenol-A (BPA) analogs tetrabromobisphenol-A (TBBPA) and tetrachlorobisphenol-A (TCBPA), could act as obesogens using zebrafish larvae as an in vivo animal model. The effect of embryonic exposure to these chemicals on lipid accumulation was analyzed by Oil Red-O staining, and correlated to their capacity to activate human and zebrafish peroxisome proliferator-activated receptor gamma (PPARγ) in zebrafish and in reporter cell lines. Then, the metabolic fate of TBBPA and TCBPA in zebrafish larvae was analyzed by high-performance liquid chromatography (HPLC) . TBBPA and TCBPA were readily taken up by the fish embryo and both compounds were biotransformed to sulfate-conjugated metabolites. Both halogenated-BPAs, as well as TBBPA-sulfate induced lipid accumulation in zebrafish larvae. TBBPA and TCBPA also induced late-onset weight gain in juvenile zebrafish. These effects correlated to their capacity to act as zebrafish PPARγ agonists. Screening of chemicals for inherent obesogenic capacities through the zebrafish lipid accumulation model could facilitate prioritizing chemicals for further investigations in rodents, and ultimately, help protect humans from exposure to environmental obesogens. PMID:24591153

  16. A reconnaissance study of halogenated organic compounds in catfish from the lower Mississippi river and its major tributaries

    USGS Publications Warehouse

    Leiker, T.J.; Rostad, C.E.; Barnes, C.R.; Pereira, W.E.

    1991-01-01

    Blue catfish, (Ictarurus furcatus), black bullhead catfish, (Ictalurus melas), channel catfish (Ictalurus punctatus), and flathead catfish (Pylodictus olivaris), were collected along a 1200 mile river reach of the Mississippi River and its major tributaries. Tissue samples were extracted and analyzed by fused silica capillary gas chromatography/mass spectrometry (GC/MS) to determine the concentrations of hydrophobic organic halogenated contaminants that have bioconcentrated within the tissues. The compounds identified in the tissue include chlordane, polychlorinated biphenyls (PCBs), DDT and its metabolites along with several other chlorinated pesticides. The data indicates that the southern reach of the river system appears to be more contaminated than the middle and upper reaches of the study area.

  17. Radiocarbon evidence for a naturally produced, bioaccumulating halogenated organic compound.

    PubMed

    Reddy, Christopher M; Xu, Li; O'Neil, Gregory W; Nelson, Robert K; Eglinton, Timothy I; Faulkner, D John; Norstrom, Ross; Ross, Peter S; Tittlemier, Sheryl A

    2004-04-01

    Halogenated organic compounds (HOCs) such as 1,1'-dimethyl-3,3',4,4'-tetrabromo-5,5'-dichloro-2,2'-bipyrrole (DBP-Br4Cl2) and heptachloro-1'-methyl-1,2'-bipyrrole (Q1) have been detected worldwide, sometimes at high levels in Antarctic air, seabird eggs, the blubber of marine mammals, and, most notably, even human milk. To date, it has been difficult to determine whether these compounds are natural products or derived from industrial synthesis. Molecular-level 14C analysis of these compounds is particularly appealing because most industrial compounds are manufactured from petrochemicals (14C-free) and natural compounds should have "modern" or "contemporary" 14C levels. To investigate the source of DBP-Br4Cl2, we isolated 600 microg of this compound (150 microg of carbon) from marine animal extracts by employing gel permeation chromatography, Florisil column chromatography, and two-dimensional preparative capillary gas chromatography. The purified DBP-Br4Cl2 was split into two samples (75 microg of carbon each) and analyzed by accelerator mass spectrometry for 14C content. The delta14C values were -449 percent per thousand and -467 percent per thousand, corresponding to conventional 14C ages of 4740 and 5000 years before present (BP), respectively. The presence of detectable 14C in the DBP-Br4Cl2 strongly points to at least a natural or biogenic source. However, these delta14C values for DBP-Br4Cl2 are more depleted than expected for a recently synthesized natural product. Several explanations are discussed, but additional samples

  18. Halogen Chemistry at North American Coastal Sites

    NASA Astrophysics Data System (ADS)

    Stutz, J.; Pikelnaya, O.; Laskin, A.; Sumner, A.; Jobson, B. T.; Finley, B.; Lawler, M.; Saltzman, E. S.; Pszenny, A. A.; Deegan, B.

    2007-12-01

    In recent years observational evidence has emerged that reactive halogen species (RHS), such as chlorine atoms, and bromine and iodine oxides, are present in coastal areas. Their chemistry can be significant as they catalytically destroy O3; oxidize hydrocarbons, dimethylsulfide, and S(IV); and modify NOx and HOx cycling. Despite their potential importance our observational database on RHS is still very limited. Most observations of RHS thus far have been made in clean areas and very few observations along the North American coast have been made. Here we will review our current understanding of RHS chemistry in both clean and polluted environments. Recent observations at coastal areas around the world will be discussed. We will also give an overview of an experiment performed by our group in Malibu, CA in October 2006 and present initial results. A suite of trace gases and environmental parameters, including halogen molecules, halogen oxides, Cl + VOC reaction products, aerosol composition, O3, NOx, CO, VOCs, meteorology, and radiation, were measured during a three week period. In addition, Cl + VOC reaction products were measured at two locations in urban Los Angeles. Clear evidence for the presence of various halogen species on the California coast was found. Observations during periods with relatively clean marine air and during times where our site was in the outflow of Los Angeles show the impact of pollution on coastal atmospheric chemistry. Our observations will be compared to earlier studies of halogen chemistry at coastal areas to further advance our understanding of halogen chemistry.

  19. A new class of halogen bonds that avoids the σ-hole

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Ma, Ning; Wang, Weizhou

    2012-04-01

    A new class of halogen bonds of the type X = Hal⋯Y has been investigated by using the density functional theory calculations. The strength of this new class of halogen bonds is in the range of 90-120 kcal/mol, which is greatly larger than that of the conventional halogen bond of the type X-Hal⋯Y. The geometry of this new class of halogen bonds is not determined by the halogen's positive σ-hole. Natural bond orbital analysis shows it is the n → π∗ interaction that determines the geometry of this new class of halogen bonds. Experimental results are in good agreement with the theoretical predictions.

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

    NASA Astrophysics Data System (ADS)

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

    2017-12-01

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

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

    PubMed

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

    2018-03-01

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

  2. 13C and 19F solid-state NMR and X-ray crystallographic study of halogen-bonded frameworks featuring nitrogen-containing heterocycles.

    PubMed

    Szell, Patrick M J; Gabriel, Shaina A; Gill, Russell D D; Wan, Shirley Y H; Gabidullin, Bulat; Bryce, David L

    2017-03-01

    Halogen bonding is a noncovalent interaction between the electrophilic region of a halogen (σ-hole) and an electron donor. We report a crystallographic and structural analysis of halogen-bonded compounds by applying a combined X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (SSNMR) approach. Single-crystal XRD was first used to characterize the halogen-bonded cocrystals formed between two fluorinated halogen-bond donors (1,4-diiodotetrafluorobenzene and 1,3,5-trifluoro-2,4,6-triiodobenzene) and several nitrogen-containing heterocycles (acridine, 1,10-phenanthroline, 2,3,5,6-tetramethylpyrazine, and hexamethylenetetramine). New structures are reported for the following three cocrystals, all in the P2 1 /c space group: acridine-1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C 6 F 3 I 3 ·C 13 H 9 N, 1,10-phenanthroline-1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C 6 F 3 I 3 ·C 12 H 8 N 2 , and 2,3,5,6-tetramethylpyrazine-1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C 6 F 3 I 3 ·C 8 H 12 N 2 . 13 C and 19 F solid-state magic-angle spinning (MAS) NMR is shown to be a convenient method to characterize the structural features of the halogen-bond donor and acceptor, with chemical shifts attributable to cocrystal formation observed in the spectra of both nuclides. Cross polarization (CP) from 19 F to 13 C results in improved spectral sensitivity in characterizing the perfluorinated halogen-bond donor when compared to conventional 1 H CP. Gauge-including projector-augmented wave density functional theory (GIPAW DFT) calculations of magnetic shielding constants, along with optimization of the XRD structures, provide a final set of structures in best agreement with the experimental 13 C and 19 F chemical shifts. Data for carbons bonded to iodine remain outliers due to well-known relativistic effects.

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

    PubMed

    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.

  4. Contamination of estuarine water, biota, and sediment by halogenated organic compounds: A field study

    USGS Publications Warehouse

    Pereira, W.E.; Rostad, C.E.; Chiou, C.T.; Brinton, T.I.; Barber, L.B.; Demcheck, D.K.; Demas, C.R.

    1988-01-01

    Studies conducted in the vicinity of an industrial outfall in the Calcasieu River estuary, Louisiana, have shown that water, bottom and suspended sediment, and four different species of biota are contaminated with halogenated organic compounds (HOC) including haloarenes. A "salting-out" effect in the estuary moderately enhanced the partitioning tendency of the contaminants into biota and sediments. Contaminant concentrations in water, suspended sediments, and biota were found to be far below the values predicted on the basis of the assumption of phase equilibria with respect to concentrations in bottom sediment. Relative concentration factors of HOC between biota (catfish) and bottom sediment increased with increasing octanol/estuarine water partition coefficients (Kow*), maximizing at log Kow* of about 5, although these ratios were considerably less than equilibrium values. In contrast, contaminant concentrations in water, biota, and suspended sediments were much closer to equilibrium values. Bioconcentration factors of HOC determined on the basis of lipid content for four different biotic species correlated reasonably well with equilibrium triolein/water partition coefficients (Ktw).

  5. Sources of halogens in the environment, influences on human and animal health.

    PubMed

    Fuge, R

    1988-06-01

    Of the halogens, fluorine has the highest crustal abundance (544 mg/kg) while iodine has the lowest (0.25 mg/kg), however, chlorine is by far the most abundant halogen in the cosmos. The geochemistries of the four naturally occurring halogens have some similarities with fluorine, chlorine and bromine being classified as lithophile elements while iodine is more chalcophile in nature. Bromine and iodine behave in a similar fashion in the secondary environment and could be classified as biophile elements being concentrated in organic matter. Chlorine, bromine and iodine are strongly enriched in the sea while iodine and to a lesser extent bromine are further concentrated in the marine algae.Apart from the occurrence of fluorine in fluorite (CaF2) there are few commonly occurring minerals which contain the halogens as essential constituents. In the igneous environment fluorine and chlorine tend to occupy hydroxyl lattice sites in micas, amphiboles, apatites etc., while in sediments clays can contain appreciable quantities of these elements. Bromine and iodine, however, would be unlikely to fit into the lattice sites of common rock-forming minerals.Bromine, like iodine, is probably volatilised from the marine environment and is carried on to land surfaces. This behaviour of iodine and bromine is reflected in the increased I/CI and Br/CI ratios of surface run-off in continental compared with near coastal environments.Limited information on the soil geochemistry of the halogens suggests that the soil contents of chlorine, bromine and iodine are influenced by proximity to the sea. Soil fluorine, however, is generally dependent on its content in the parent material. In some areas pollutant sources of the halogens contribute appreciably to their concentration in the environment.Iodine and chlorine are essential elements for mammals and fluorine has been shown to have beneficial effects on bone and tooth formation. However, excess quantities of dietary fluorine can be harmful

  6. Treatment of halogen-containing waste and other waste materials

    DOEpatents

    Forsberg, Charles W.; Beahm, Edward C.; Parker, George W.

    1997-01-01

    A process for treating a halogen-containing waste material. The process provides a bath of molten glass containing a sacrificial metal oxide capable of reacting with a halogen in the waste material. The sacrificial metal oxide is present in the molten glass in at least a stoichiometric amount with respect to the halogen in the waste material. The waste material is introduced into the bath of molten glass to cause a reaction between the halogen in the waste material and the sacrificial metal oxide to yield a metal halide. The metal halide is a gas at the temperature of the molten glass. The gaseous metal halide is separated from the molten glass and contacted with an aqueous scrubber solution of an alkali metal hydroxide to yield a metal hydroxide or metal oxide-containing precipitate and a soluble alkali metal halide. The precipitate is then separated from the aqueous scrubber solution. The molten glass containing the treated waste material is removed from the bath as a waste glass. The process of the invention can be used to treat all types of waste material including radioactive wastes. The process is particularly suited for separating halogens from halogen-containing wastes.

  7. Metal-organic scintillator crystals for X-ray, gamma ray, and neutron detection

    DOEpatents

    Boatner, Lynn A [Oak Ridge, TN; Kolopus, James A [Clinton, TN; Neal, John S [Knoxville, TN; Ramey, Joanne Oxendine [Knoxville, TN; Wisniewski, Dariusz J [Torun, PL

    2012-01-03

    New metal-organic materials are useful as scintillators and have the chemical formula LX.sub.3(CH.sub.3OH).sub.4 where L is Y, Sc, or a lanthanide element, and X is a halogen element. An example of the scintillator materials is CeCl.sub.3(CH.sub.3OH).sub.4.

  8. Halogen-free boron based electrolyte solution for rechargeable magnesium batteries

    NASA Astrophysics Data System (ADS)

    Zhu, Jinjie; Guo, Yongsheng; Yang, Jun; Nuli, Yanna; Zhang, Fan; Wang, Jiulin; Hirano, Shin-ichi

    2014-02-01

    All halogen containing electrolytes for Mg battery are apt to corrode conventional metal current collectors. In this paper, a new type of halogen-free boron based electrolyte (Mg[Mes3BPh]2/THF) is designed and prepared. Electrochemical tests show that this electrolyte system possesses high ion conductivity (1.5 × 10-3 S cm-1) and good Mg deposition-dissolution reversibility. More importantly, the same electrochemical window (2.6 V vs. Mg RE) of the electrolyte on Pt and stainless steel electrodes indicates that halogen-free electrolyte indeed lessens the corrosion to conventional metal current collectors. The surface morphologies of stainless steel, aluminum and copper are further observed after their anodic potentiostatic polarization in 0.25 mol L-1 Mg[Mes3BPh]2/THF electrolyte solution for 2 days. A comparison with halogen containing electrolytes proves that the presence of halogen in electrolyte is the reason for corrosion. This work provides a stepping stone for developing new halogen-free electrolyte systems for rechargeable Mg batteries.

  9. 40 CFR 721.2140 - Carbo-poly-cycli-col azo-alkyl-aminoalkyl-carbo-mono-cyclic ester, halogen acid salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... subject to reporting. (1) The chemical substance generically identified as carbopolycyclicol azo-al-kyl-a-mino-al-kyl-car-bo-mon-o-cyc-lic ester, halogen acid salt (PMN P-88-1682) is subject to reporting under...

  10. 40 CFR 721.2140 - Carbo-poly-cycli-col azo-alkyl-aminoalkyl-carbo-mono-cyclic ester, halogen acid salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... subject to reporting. (1) The chemical substance generically identified as carbopolycyclicol azo-al-kyl-a-mino-al-kyl-car-bo-mon-o-cyc-lic ester, halogen acid salt (PMN P-88-1682) is subject to reporting under...

  11. 40 CFR 721.2140 - Carbo-poly-cycli-col azo-alkyl-aminoalkyl-carbo-mono-cyclic ester, halogen acid salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... subject to reporting. (1) The chemical substance generically identified as carbopolycyclicol azo-al-kyl-a-mino-al-kyl-car-bo-mon-o-cyc-lic ester, halogen acid salt (PMN P-88-1682) is subject to reporting under...

  12. 40 CFR 721.2140 - Carbo-poly-cycli-col azo-alkyl-aminoalkyl-carbo-mono-cyclic ester, halogen acid salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... subject to reporting. (1) The chemical substance generically identified as carbopolycyclicol azo-al-kyl-a-mino-al-kyl-car-bo-mon-o-cyc-lic ester, halogen acid salt (PMN P-88-1682) is subject to reporting under...

  13. Investigating Planetary Volatile Accretion Mechanisms Using the Halogens

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Depletion of the volatile elements in the Earth relative to the CI chondrites is roughly correlated with volatility, or decreasing condensation temperature. For the heavy halogen group elements (Cl, Br and I), volatility alone does not account for their apparent depletion, which early data has suggested is far greater than predicted [1-2]. Such depletion has been used to argue for the preferential loss of halogens by, amongst other processes, impact-driven erosive loss from Earth's surface [2]. Little consensus exists as to why the halogens should exhibit such preferential behavior during accretionary processes. Early efforts to constrain halogen abundance and understand their behavior in both Earth and planetary materials [3-6] have been hampered by their typically low abundance (ppb level) in most geologic materials. We present the results of halogen analysis of 23 chondrite samples, selected to represent diverse groups and petrologic type. Halogen abundances were measured by neutron irradiation noble gas mass spectrometry (NI-NGMS). Significant concentration heterogeneity is observed within some samples. However, a single Br/Cl and I/Cl ratio of 1.9 ± 0.2 (x 10-3) and 335 ± 10 (x 10-6) can be defined for carbonaceous chondrites with a good correlation between Br and Cl (R2 = 0.97) and between I and Cl (R2 = 0.84). Ratios of I/Cl overlap with terrestrial estimates of Bulk Silicate Earth and Mid Ocean Ridge Basalts. Similarly, good correlations are derived for enstatite (E) chondrites and a sulfide- and halogen- rich subset of E-chondrites. Chlorine abundances of CI (Orgueil) in this study are lower by factor of ~ 3 than the value of ~ 700 ppm Cl (compilation in [1]). Our results are similar to early discarded low values for Ivuna and Orgueil from [5,6] and agree more closely with values for CM chondrites. Halogens may not be as depleted in Earth as previously suggested, or a high degree of heterogeneity in the abundance of these volatile elements in

  14. A quantum chemical study of the structures, stability, and spectroscopy of halogen- and hydrogen-boned complexes between cyanoacetaldehyde and hypochlorous acids

    NASA Astrophysics Data System (ADS)

    Tang, Qingjie; Guo, Zhenfu; Li, Qingzhong

    2014-03-01

    The complexes of cyanoacetaldehyde and hypohalous acid (HOX, X = Cl, Br, and I) have been investigated. They can form six different structures (A, B, C, D, E, and F), the former three structures are mainly combined through a N(O)⋯X halogen bond and the latter three structures are maintained mainly by a N(O)⋯H hydrogen bond, although other weaker interactions are also present in most structures. The hydrogen-bonded structures are more stable than the respective halogen-bonded structures. The Osbnd H and Osbnd X bonds in the halogen- and hydrogen-bonded complexes are lengthened and show an observed red shift, while those in the weaker secondary interactions are contracted and display a small blue shift. The orbital interactions in NBO analysis and the electron densities in AIM analysis provide useful and reliable information for the strength of each type of interaction in different structures.

  15. Synthesis, Characterization, and Multimillion-Atom Simulation of Halogen-Based Energetic Materials for Agent Defeat

    DTIC Science & Technology

    2013-04-01

    DTRA-TR-13-23 Synthesis, Characterization, and Multimillion -Atom Simulation of Halogen-Based Energetic Materials for Agent Defeat Approved for...reagents for the destruction of biologically active materials and a simulation of their reactions on a multimillion atom scale with quantum...explosives for destruction of chemical & biological agents. Multimillion -atom molecular dynamics simulations with quantum mechanical accuracy were

  16. Treatment of halogen-containing waste and other waste materials

    DOEpatents

    Forsberg, C.W.; Beahm, E.C.; Parker, G.W.

    1997-03-18

    A process is described for treating a halogen-containing waste material. The process provides a bath of molten glass containing a sacrificial metal oxide capable of reacting with a halogen in the waste material. The sacrificial metal oxide is present in the molten glass in at least a stoichiometric amount with respect to the halogen in the waste material. The waste material is introduced into the bath of molten glass to cause a reaction between the halogen in the waste material and the sacrificial metal oxide to yield a metal halide. The metal halide is a gas at the temperature of the molten glass. The gaseous metal halide is separated from the molten glass and contacted with an aqueous scrubber solution of an alkali metal hydroxide to yield a metal hydroxide or metal oxide-containing precipitate and a soluble alkali metal halide. The precipitate is then separated from the aqueous scrubber solution. The molten glass containing the treated waste material is removed from the bath as a waste glass. The process of the invention can be used to treat all types of waste material including radioactive wastes. The process is particularly suited for separating halogens from halogen-containing wastes. 3 figs.

  17. Halogenated Peptides as Internal Standards (H-PINS)

    PubMed Central

    Mirzaei, Hamid; Brusniak, Mi-Youn; Mueller, Lukas N.; Letarte, Simon; Watts, Julian D.; Aebersold, Ruedi

    2009-01-01

    As the application for quantitative proteomics in the life sciences has grown in recent years, so has the need for more robust and generally applicable methods for quality control and calibration. The reliability of quantitative proteomics is tightly linked to the reproducibility and stability of the analytical platforms, which are typically multicomponent (e.g. sample preparation, multistep separations, and mass spectrometry) with individual components contributing unequally to the overall system reproducibility. Variations in quantitative accuracy are thus inevitable, and quality control and calibration become essential for the assessment of the quality of the analyses themselves. Toward this end, the use of internal standards cannot only assist in the detection and removal of outlier data acquired by an irreproducible system (quality control) but can also be used for detection of changes in instruments for their subsequent performance and calibration. Here we introduce a set of halogenated peptides as internal standards. The peptides are custom designed to have properties suitable for various quality control assessments, data calibration, and normalization processes. The unique isotope distribution of halogenated peptides makes their mass spectral detection easy and unambiguous when spiked into complex peptide mixtures. In addition, they were designed to elute sequentially over an entire aqueous to organic LC gradient and to have m/z values within the commonly scanned mass range (300–1800 Da). In a series of experiments in which these peptides were spiked into an enriched N-glycosite peptide fraction (i.e. from formerly N-glycosylated intact proteins in their deglycosylated form) isolated from human plasma, we show the utility and performance of these halogenated peptides for sample preparation and LC injection quality control as well as for retention time and mass calibration. Further use of the peptides for signal intensity normalization and retention time

  18. Assessing California groundwater susceptibility using trace concentrations of halogenated volatile organic compounds

    USGS Publications Warehouse

    Deeds, Daniel A.; Kulongoski, Justin T.; Belitz, Kenneth

    2012-01-01

    Twenty-four halogenated volatile organic compounds (hVOCs) and SF6 were measured in groundwater samples collected from 312 wells across California at concentrations as low as 10–12 grams per kilogram groundwater. The hVOCs detected are predominately anthropogenic (i.e., “ahVOCs”) and as such their distribution delineates where groundwaters are impacted and susceptible to human activity. ahVOC detections were broadly consistent with air-saturated water concentrations in equilibrium with a combination of industrial-era global and regional hVOC atmospheric abundances. However, detection of ahVOCs in nearly all of the samples collected, including ancient groundwaters, suggests the presence of a sampling or analytical artifact that confounds interpretation of the very-low concentration ahVOC data. To increase our confidence in ahVOC detections we establish screening levels based on ahVOC concentrations in deep wells drawing ancient groundwater in Owens Valley. Concentrations of ahVOCs below the Owens Valley screening levels account for a large number of the detections in prenuclear groundwater across California without significant loss of ahVOC detections in shallow, recently recharged groundwaters. Over 80% of the groundwaters in this study contain at least one ahVOC after screening, indicating that the footprint of human industry is nearly ubiquitous and that most California groundwaters are vulnerable to contamination from land-surface activities.

  19. Integrated system for the destruction of organics by hydrolysis and oxidation with peroxydisulfate

    DOEpatents

    Cooper, John F.; Balazs, G. Bryan; Hsu, Peter; Lewis, Patricia R.; Adamson, Martyn G.

    2000-01-01

    An integrated system for destruction of organic waste comprises a hydrolysis step at moderate temperature and pressure, followed by direct chemical oxidation using peroxydisulfate. This system can be used to quantitatively destroy volatile or water-insoluble halogenated organic solvents, contaminated soils and sludges, and the organic component of mixed waste. The hydrolysis step results in a substantially single phase of less volatile, more water soluble hydrolysis products, thus enabling the oxidation step to proceed rapidly and with minimal loss of organic substrate in the off-gas.

  20. Chemical Characterization of Dissolved Organic Matter (DOM) in Seawater: Structure, Cycling and the Role of Biology

    DTIC Science & Technology

    2005-02-01

    concentration, excluding hydrocarbons , was less than 2% of the total organic carbon present in the samples, and the samples had not been pre-extracted to...carbon chains that make up the separation phase of the C18 134 column. This carbon chain was most likely generated from petroleum products, and had a...produced, bioaccumulating halogenated organic compound. Environmental Science and Technology 38: 1992-1997. Silfer, J. A., M. H. Engel and S. A

  1. Scientific conferences: A big hello to halogen bonding

    NASA Astrophysics Data System (ADS)

    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.

  2. Emission of Volatile OrganoHalogens by Southern African Solar Salt Works

    NASA Astrophysics Data System (ADS)

    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

  3. The Important Role of Halogen Bond in Substrate Selectivity of Enzymatic Catalysis

    NASA Astrophysics Data System (ADS)

    Jiang, Shuiqin; Zhang, Lujia; Cui, Dongbin; Yao, Zhiqiang; Gao, Bei; Lin, Jinping; Wei, Dongzhi

    2016-10-01

    The use of halogen bond is widespread in drug discovery, design, and clinical trials, but is overlooked in drug biosynthesis. Here, the role of halogen bond in the nitrilase-catalyzed synthesis of ortho-, meta-, and para-chlorophenylacetic acid was investigated. Different distributions of halogen bond induced changes of substrate binding conformation and affected substrate selectivity. By engineering the halogen interaction, the substrate selectivity of the enzyme changed, with the implication that halogen bond plays an important role in biosynthesis and should be used as an efficient and reliable tool in enzymatic drug synthesis.

  4. Importance of reactive halogens in the tropical marine atmosphere using WRF-chem

    NASA Astrophysics Data System (ADS)

    Badia, Alba; Reeves, Claire E.; Baker, Alex; Volkamer, Rainer; Apel, Eric; Saiz-Lopez, Alfonso; von Glasow, Roland

    2017-04-01

    Halogen species (chlorine, bromine and iodine) are known to play an important role in the chemistry and oxidizing capacity of the troposphere, particularly in the marine boundary layer (MBL). Reactive halogens participate in catalytic reaction cycles that efficiently destroy O3, change the HOX and NOX partitioning, affect the oxidation of volatile organic compounds (VOCs) and mercury, reduce the lifetime of methane, and take part in new particle formation. Numerical models predicted that reactive halogen compounds account for 30% of O3 destruction in the MBL and 5-20% globally. Up to 34% of O3 loss in the tropical East Pacific is due to I and Br combined. Recent studies have highlighted the key role that heterogeneous chemistry plays in explaining observations of BrO and IO abundances in the tropical troposphere. The main objective of this study is to investigate the atmospheric chemistry in the tropical East Pacific with a focus on reactive halogens using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) and field data from the TORERO campaign. Our reaction mechanism in WRF-Chem is based on the MOZART mechanism and has been extended to include bromine, chlorine and iodine chemistry. Heterogeneous recycling reactions involving sea-salt aerosol and other particles have been included into the model, along with oceanic emissions of important OVOCs and halocarbons. Sea surface emissions of inorganic iodine are calculated using the parameterisation of Carpenter et al., 2013. Focusing on TORERO observations from the ships and a selected number of flights we present the tropospheric impacts of halogens (BrO, IO) in the tropospheric chemistry of relevant species (O3, OH and OVOCS). Sensitivity runs are made in order to study the impact of heterogeneous chemistry in the iodine and bromine species partitioning. A comparison between the online calculation of Very Short Lived Halocarbons (VSLH) oceanic emissions with prescribed oceanic emissions is

  5. Halogen bonding based recognition processes: a world parallel to hydrogen bonding.

    PubMed

    Metrangolo, Pierangelo; Neukirch, Hannes; Pilati, Tullio; Resnati, Giuseppe

    2005-05-01

    Halogen bonding is the noncovalent interaction between halogen atoms (Lewis acids) and neutral or anionic Lewis bases. The main features of the interaction are given, and the close similarity with the hydrogen bonding will become apparent. Some heuristic principles are presented to develop a rational crystal engineering based on halogen bonding. The focus is on halogen-bonded supramolecular architectures given by halocarbons. The potential of the interaction is shown by useful applications in the field of synthetic chemistry, material science, and bioorganic chemistry.

  6. Design and verification of halogen-bonding system at the complex interface of human fertilization-related MUP PDZ5 domain with CAMK's C-terminal peptide.

    PubMed

    Wang, Juan; Guo, Yunjie; Zhang, Xue

    2018-02-01

    Calmodulin-dependent protein kinase (CAMK) is physiologically activated in fertilized human oocytes and is involved in the Ca 2+ response pathways that link the fertilization calmodulin signal to meiosis resumption and cortical granule exocytosis. The kinase has an unstructured C-terminal tail that can be recognized and bound by the PDZ5 domain of its cognate partner, the multi-PDZ domain protein (MUP). In the current study, we reported a rational biomolecular design of halogen-bonding system at the complex interface of CAMK's C-terminal peptide with MUP PDZ5 domain by using high-level computational approaches. Four organic halogens were employed as atom probes to explore the structural geometry and energetic property of designed halogen bonds in the PDZ5-peptide complex. It was found that the heavier halogen elements such as bromine Br and iodine I can confer stronger halogen bond but would cause bad atomic contacts and overlaps at the complex interface, while fluorine F cannot form effective halogen bond in the complex. In addition, the halogen substitution at different positions of peptide's aromatic ring would result in distinct effects on the halogen-bonding system. The computational findings were then verified by using fluorescence analysis; it is indicated that the halogen type and substitution position play critical role in the interaction strength of halogen bonds, and thus the PDZ5-peptide binding affinity can be improved considerably by optimizing their combination. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Structures and electronic states of halogen-terminated graphene nano-flakes

    NASA Astrophysics Data System (ADS)

    Tachikawa, Hiroto; Iyama, Tetsuji

    2015-12-01

    Halogen-functionalized graphenes are utilized as electronic devices and energy materials. In the present paper, the effects of halogen-termination of graphene edge on the structures and electronic states of graphene flakes have been investigated by means of density functional theory (DFT) method. It was found that the ionization potential (Ip) and electron affinity of graphene (EA) are blue-shifted by the halogen termination, while the excitation energy is red-shifted. The drastic change showed a possibility as electronic devices such as field-effect transistors. The change of electronic states caused by the halogen termination of graphene edge was discussed on the basis of the theoretical results.

  8. Structure-toxicity relationship study of para-halogenated styrene analogues in CYP2E1 transgenic cells

    PubMed Central

    Chung, Jou-Ku; Shen, Shuijie; Jiang, Zhiteng; Yuan, Wei; Zheng, Jiang

    2012-01-01

    Styrene is one of the most important industrial intermediates consumed in the world and is mainly used as a monomer for reinforced plastics and rubber. Styrene has been found to be hepatotoxic and pneumotoxic in humans and experimental animals. The toxicity of styrene is suggested to be metabolism-dependent. Styrene-7,8-oxide has been considered as the major metabolite responsible for styrene-induced cytotoxicity. The objective of the study was to investigate the correlation between cytotoxicity of styrene and chemical and biochemical properties of the vinyl group of styrene by development of structure activity relationships (SAR). 4-Fluorostyrene, 4-chlorostyrene and 4-bromostyrene were selected for the SAR study. Cytotoxicity of styrene and the halogenated styrene derivatives with an order of 4-bromostyrene > 4-chlorostyrene > 4-fluorostyrene ≈ styrene was observed in CYP2E1 transgenic cells. Similar orders in the efficiency of the metabolism of styrene and the halogenated styrene analogues to their oxides and in the electrophilicity of the corresponding oxides were observed. Additionally, the order of the potency of cellular glutathione depletion and the degree of protein adduction induced by styrene and the halogenated styrenes were consistent with that of their cytotoxicities. The wild-type cells were less susceptible to the toxicity of the corresponding model compounds than CYP2E1 cells. The present study provided insight into the roles of the biochemical and chemical properties of styrene in its cytotoxicity. PMID:22366341

  9. 40 CFR Table 1 to Subpart F of... - Synthetic Organic Chemical Manufacturing Industry Chemicals

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 10 2013-07-01 2013-07-01 false Synthetic Organic Chemical... Synthetic Organic Chemical Manufacturing Industry Pt. 63, Subpt. F, Table 1 Table 1 to Subpart F of Part 63—Synthetic Organic Chemical Manufacturing Industry Chemicals Chemical name a CAS No. b Group Acenaphthene...

  10. 40 CFR Table 1 to Subpart F of... - Synthetic Organic Chemical Manufacturing Industry Chemicals

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 10 2014-07-01 2014-07-01 false Synthetic Organic Chemical... Synthetic Organic Chemical Manufacturing Industry Pt. 63, Subpt. F, Table 1 Table 1 to Subpart F of Part 63—Synthetic Organic Chemical Manufacturing Industry Chemicals Chemical name a CAS No. b Group Acenaphthene...

  11. 40 CFR Table 1 to Subpart F of... - Synthetic Organic Chemical Manufacturing Industry Chemicals

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 10 2012-07-01 2012-07-01 false Synthetic Organic Chemical... Synthetic Organic Chemical Manufacturing Industry Pt. 63, Subpt. F, Table 1 Table 1 to Subpart F of Part 63—Synthetic Organic Chemical Manufacturing Industry Chemicals Chemical name a CAS No. b Group Acenaphthene...

  12. 40 CFR Table 1 to Subpart F of... - Synthetic Organic Chemical Manufacturing Industry Chemicals

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 9 2011-07-01 2011-07-01 false Synthetic Organic Chemical... Synthetic Organic Chemical Manufacturing Industry Pt. 63, Subpt. F, Table 1 Table 1 to Subpart F of Part 63—Synthetic Organic Chemical Manufacturing Industry Chemicals Chemical name a CAS No. b Group Acenaphthene...

  13. The halogenated metabolism of brown algae (Phaeophyta), its biological importance and its environmental significance.

    PubMed

    La Barre, Stéphane; Potin, Philippe; Leblanc, Catherine; Delage, Ludovic

    2010-03-31

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

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

    PubMed Central

    La Barre, Stéphane; Potin, Philippe; Leblanc, Catherine; Delage, Ludovic

    2010-01-01

    Brown algae represent a major component of littoral and sublittoral zones in temperate and subtropical ecosystems. An essential adaptive feature of this independent eukaryotic lineage is the ability to couple oxidative reactions resulting from exposure to sunlight and air with the halogenations of various substrates, thereby addressing various biotic and abiotic stresses i.e., defense against predators, tissue repair, holdfast adhesion, and protection against reactive species generated by oxidative processes. Whereas marine organisms mainly make use of bromine to increase the biological activity of secondary metabolites, some orders of brown algae such as Laminariales have also developed a striking capability to accumulate and to use iodine in physiological adaptations to stress. We review selected aspects of the halogenated metabolism of macrophytic brown algae in the light of the most recent results, which point toward novel functions for iodide accumulation in kelps and the importance of bromination in cell wall modifications and adhesion properties of brown algal propagules. The importance of halogen speciation processes ranges from microbiology to biogeochemistry, through enzymology, cellular biology and ecotoxicology. PMID:20479964

  15. Exhaled human breath measurement method for assessing exposure to halogenated volatile organic compounds.

    PubMed

    Pleil, J D; Lindstrom, A B

    1997-05-01

    The organic constituents of exhaled human breath are representative of blood-borne concentrations through gas exchange in the blood/breath interface in the lungs. The presence of specific compounds can be an indicator of recent exposure or represent a biological response of the subject. For volatile organic compounds (VOCs), sampling and analysis of breath is preferred to direct measurement from blood samples because breath collection is noninvasive, potentially infectious waste is avoided, and the measurement of gas-phase analytes is much simpler in a gas matrix rather than in a complex biological tissue such as blood. To exploit these advantages, we have developed the "single breath canister" (SBC) technique, a simple direct collection method for individual alveolar breath samples, and adapted conventional gas chromatography-mass spectrometry analytical methods for trace-concentration VOC analysis. The focus of this paper is to describe briefly the techniques for making VOC measurements in breath, to present some specific applications for which these methods are relevant, and to demonstrate how to estimate exposure to example VOCs on the basis of breath elimination. We present data from three different exposure scenarios: (a) vinyl chloride and cis-1,2-dichloroethene from showering with contaminated water from a private well, (b) chloroform and bromodichloromethane from high-intensity swimming in chlorinated pool water, and (c) trichloroethene from a controlled exposure chamber experiment. In all cases, for all subjects, the experiment is the same: preexposure breath measurement, exposure to halogenated VOC, and a postexposure time-dependent series of breath measurements. Data are presented only to demonstrate the use of the method and how to interpret the analytical results.

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

    PubMed

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

    2017-08-01

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

  17. Chemical Loss of Polar Ozone: Present Understanding and Remaining Uncertainties

    NASA Technical Reports Server (NTRS)

    Salawitch, Ross; Canty, Tim; Cunnold, Derek; Dorf, Marcel; Frieler, Katja; Godin-Beekman, Sophie; Newchurch, Michael; Pfeilsticker, Klaus; Rex, Markus; Stimpfle, Rick; hide

    2005-01-01

    Not long after the discovery of the Antarctic ozone hole, it was established that halogen compounds, supplied to the atmosphere mainly by anthropogenic activities, are the primary driver of polar ozone loss. We will briefly review the chemical mechanisms that cause polar ozone loss and the early evidence showing the key role played by anthropogenic halogens. Recently, stratospheric halogen loading has leveled off, due to adherence to the Montreal Protocol and its amendments that has essentially banned CFCs (chlorofluorocarbons) and other halocarbons. We will describe recent reports of the first stage of recovery of the Antarctic ozone hole (e.g., a statistically significant slowing of the downward trend), associated with the leveling off of stratospheric halogens. Despite this degree of understanding, we will discuss the tendency of photochemical models to underestimate the observed rate of polar ozone loss and a hypothesis that has recently been put forth that might resolve this discrepancy. Finally, we will briefly discuss chemical loss of Arctic ozone, which

  18. Formation of halogenated organics during waste-water disinfection

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Singer, P.C.; Brown, R.A.; Wiseman, J.F.

    The research examined the formation of trihalomethanes (THMs) and total organic halides (TOX) during wastewater chlorination at three wastewater treatment plants in the central Piedmont of North Carolina. Secondary effluent samples were collected before and after the addition of chlorine at each of the three treatment facilities; chlorinated samples were taken from various locations within the chlorine contact chambers and at the plant discharge. Water samples were also collected upstream and downstream from two of the plant outfalls to determine the increase and persistence of THMs and TOX below each plant. TOX and THM formation was evaluated in terms ofmore » effluent wastewater quality (e.g., residual chemical oxygen demand, total organic carbon and ammonia concentration), chlorine dose, chlorine contacting system, methods of chlorine addition, and chlorine-to-ammonia ratio. The results showed that TOX was present in the unchlorinated wastewater and that additional TOX was formed immediately after chlorine addition. Small to insignificant amounts of THMS were detected. TOX formation did not increase with increasing contact time, due to the rapid depletion of free chlorine and the formation of combined chlorine in the chlorine contact chamber.« less

  19. Ultrahigh-yield growth of GaN via halogen-free vapor-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Nakamura, Daisuke; Kimura, Taishi

    2018-06-01

    The material yield of Ga during GaN growth via halogen-free vapor-phase epitaxy (HF-VPE) was systematically investigated and found to be much higher than that obtained using conventional hydride VPE. This is attributed to the much lower process pressure and shorter seed-to-source distance, owing to the inherent chemical reactions and corresponding reactor design used for HF-VPE growth. Ultrahigh-yield GaN growth was demonstrated on a 4-in.-diameter sapphire seed substrate.

  20. Metal halogen battery system with multiple outlet nozzle for hydrate

    DOEpatents

    Bjorkman, Jr., Harry K.

    1983-06-21

    A metal halogen battery system, including at least one cell having a positive electrode and a negative electrode contacted by aqueous electrolyte containing the material of said metal and halogen, store means whereby halogen hydrate is formed and stored as part of an aqueous material, means for circulating electrolyte through the cell and to the store means, and conduit means for transmitting halogen gas formed in the cell to a hydrate former whereby the hydrate is formed in association with the store means, said store means being constructed in the form of a container which includes a filter means, said filter means being inoperative to separate the hydrate formed from the electrolyte, said system having, a hydrate former pump means associated with the store means and being operative to intermix halogen gas with aqueous electrolyte to form halogen hydrate, said hydrate former means including, multiple outlet nozzle means connected with the outlet side of said pump means and being operative to minimize plugging, said nozzle means being comprised of at least one divider means which is generally perpendicular to the rotational axes of gears within the pump means, said divider means acting to divide the flow from the pump means into multiple outlet flow paths.

  1. Identifying Chemical Groups for Biomonitoring

    PubMed Central

    Krowech, Gail; Hoover, Sara; Plummer, Laurel; Sandy, Martha; Zeise, Lauren; Solomon, Gina

    2016-01-01

    Summary: Regulatory agencies face daunting challenges identifying emerging chemical hazards because of the large number of chemicals in commerce and limited data on exposure and toxicology. Evaluating one chemical at a time is inefficient and can lead to replacement with uncharacterized chemicals or chemicals with structural features already linked to toxicity. The Office of Environmental Health Hazard Assessment (OEHHA) has developed a process for constructing and assessing chemical groups for potential biomonitoring in California. We screen for chemicals with significant exposure potential and propose possible chemical groups, based on structure and function. To support formal consideration of these groups by Biomonitoring California’s Scientific Guidance Panel, we conduct a detailed review of exposure and toxicity data and examine the likelihood of detection in biological samples. To date, 12 chemical groups have been constructed and added to the pool of chemicals that can be selected for Biomonitoring California studies, including p,p´-bisphenols, brominated and chlorinated organic compounds used as flame retardants, non-halogenated aromatic phosphates, and synthetic polycyclic musks. Evaluating chemical groups, rather than individual chemicals, is an efficient way to respond to shifts in chemical use and the emergence of new chemicals. This strategy can enable earlier identification of important chemicals for monitoring and intervention. PMID:27905275

  2. Understanding the Halogenation Effects in Diketopyrrolopyrrole-Based Small Molecule Photovoltaics.

    PubMed

    Sun, Shi-Xin; Huo, Yong; Li, Miao-Miao; Hu, Xiaowen; Zhang, Hai-Jun; Zhang, You-Wen; Zhang, You-Dan; Chen, Xiao-Long; Shi, Zi-Fa; Gong, Xiong; Chen, Yongsheng; Zhang, Hao-Li

    2015-09-16

    Two molecules containing a central diketopyrrolopyrrole and two oligothiophene units have been designed and synthesized. Comparisons between the molecules containing terminal F (FDPP) and Cl (CDPP) atoms allowed us to evaluate the effects of halogenation on the photovoltaic properties of the small molecule organic solar cells (OSCs). The OSCs devices employing FDPP:PC71BM films showed power conversion efficiencies up to 4.32%, suggesting that fluorination is an efficient method for constructing small molecules for OSCs.

  3. Effectiveness of Halogen-Based Disinfectants Against Acinetobacter Baumannii: Wound Care and Environmental Decontamination

    DTIC Science & Technology

    2006-11-01

    EFFECTIVENESS OF HALOGEN-BASED DISINFECTANTS AGAINST Acinetobacter baumannii: WOUND CARE AND ENVIROMENTAL DECONTAMINATION James...a standard E. coli comparator, in a novel bacterial culture system that incorporated a three log range of organic growth media concentrations. We...report the highest dilutions of stock disinfectant able to inhibit replication or kill the bacteria , denoted as the maximum inhibitory dilution

  4. Intrinsic Chemiluminescence Generation during Advanced Oxidation of Persistent Halogenated Aromatic Carcinogens.

    PubMed

    Mao, Li; Liu, Yu-Xiang; Huang, Chun-Hua; Gao, Hui-Ying; Kalyanaraman, Balaraman; Zhu, Ben-Zhan

    2015-07-07

    The ubiquitous distribution coupled with their carcinogenicity has raised public concerns on the potential risks to both human health and the ecosystem posed by the halogenated aromatic compounds (XAr). Recently, advanced oxidation processes (AOPs) have been increasingly favored as an "environmentally-green" technology for the remediation of such recalcitrant and highly toxic XAr. Here, we show that AOPs-mediated degradation of the priority pollutant pentachlorophenol and all other XAr produces an intrinsic chemiluminescence that directly depends on the generation of the extremely reactive hydroxyl radicals. We propose that the hydroxyl radical-dependent formation of quinoid intermediates and electronically excited carbonyl species is responsible for this unusual chemiluminescence production. A rapid, sensitive, simple, and effective chemiluminescence method was developed to quantify trace amounts of XAr and monitor their real-time degradation kinetics. These findings may have broad biological and environmental implications for future research on this important class of halogenated persistent organic pollutants.

  5. Remarkable effect of halogenation of aromatic compounds on efficiency of nanowire formation through polymerization/crosslinking by high-energy single particle irradiation

    NASA Astrophysics Data System (ADS)

    Horio, Akifumi; Sakurai, Tsuneaki; Kayama, Kazuto; Lakshmi, G. B. V. S.; Kumar Avasthi, Devesh; Sugimoto, Masaki; Yamaki, Tetsuya; Chiba, Atsuya; Saito, Yuichi; Seki, Shu

    2018-01-01

    Irradiation of high-energy ion particles on organic films induced solid-state polymerization and crosslinking reactions of the materials along the ion trajectories, resulting in the formation of insoluble uniform nanowires with a precise diameter. The nanowires were isolated by the development process i.e. the irradiated film was immersed in organic solvents, and their morphology was visualized by atomic force microscopy. The target organic materials are 4-vinyltriphenylamine, poly(4-vinyltriphenylamine), and polystyrene derivatives with/without the partial substitutions by halogen atoms. It was found that 4-vinyltriphenylamines, in spite of their small molecular sizes, afforded nanowires more clearly than poly(4-vinyltriphenylamine)s. Moreover, the efficiency of demonstrated polymerization/crosslinking reactions obviously depends on the substituted halogen atom species. The averaged diameters of nanowires from bromo- or iodo- substituted 4-vinyltriphenylamine (9.3 and 9.4 nm, respectively) were larger than that obtained from simple 4-vinyltriphenylamine (6.8 nm). The remarkable effect of halogenation of aromatic compounds on the efficiency of the radiation-induced reactions was also observed for polystyrene derivatives. This contrast was considered to originate from the sum of the efficiency of elementary reactions including dissociative electron attachment.

  6. Extending Halogen-based Medicinal Chemistry to Proteins

    PubMed Central

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

    2016-01-01

    Insulin, a protein critical for metabolic homeostasis, provides a classical model for protein design with application to human health. Recent efforts to improve its pharmaceutical formulation demonstrated that iodination of a conserved tyrosine (TyrB26) enhances key properties of a rapid-acting clinical analog. Moreover, the broad utility of halogens in medicinal chemistry has motivated the use of hybrid quantum- and molecular-mechanical methods to study proteins. Here, we (i) undertook quantitative atomistic simulations of 3-[iodo-TyrB26]insulin to predict its structural features, and (ii) tested these predictions by X-ray crystallography. Using an electrostatic model of the modified aromatic ring based on quantum chemistry, the calculations suggested that the analog, as a dimer and hexamer, exhibits subtle differences in aromatic-aromatic interactions at the dimer interface. Aromatic rings (TyrB16, PheB24, PheB25, 3-I-TyrB26, and their symmetry-related mates) at this interface adjust to enable packing of the hydrophobic iodine atoms within the core of each monomer. Strikingly, these features were observed in the crystal structure of a 3-[iodo-TyrB26]insulin analog (determined as an R6 zinc hexamer). Given that residues B24–B30 detach from the core on receptor binding, the environment of 3-I-TyrB26 in a receptor complex must differ from that in the free hormone. Based on the recent structure of a “micro-receptor” complex, we predict that 3-I-TyrB26 engages the receptor via directional halogen bonding and halogen-directed hydrogen bonding as follows: favorable electrostatic interactions exploiting, respectively, the halogen's electron-deficient σ-hole and electronegative equatorial band. Inspired by quantum chemistry and molecular dynamics, such “halogen engineering” promises to extend principles of medicinal chemistry to proteins. PMID:27875310

  7. Implementation of marine halogen chemistry into the Community Multiscale Air Quality (CMAQ) model

    NASA Astrophysics Data System (ADS)

    Gantt, B.; Sarwar, G.

    2017-12-01

    In two recent studies (Sarwar et al, 2015 and Gantt et al., 2017), the impact of marine halogen (bromine and iodine) chemistry on air quality has been evaluated using the Community Multiscale Air Quality (CMAQ) model. We found that marine halogen chemistry not only has the expected effect of reducing marine boundary layer ozone concentrations, but also reduces ozone in the free troposphere and inland from the coast. In Sarwar et al. (2015), the impact of the halogen chemistry without and with photochemical reactions of higher iodine oxides over the Northern Hemisphere was examined using the coarse horizontal grids of a hemispheric domain. Halogen chemistry without and with the photochemical reactions of higher iodine oxides reduces ozone over seawater by 15% and 48%, respectively. Using the results of the chemistry without the photochemical reactions of higher iodine oxides, we developed a simple first order ozone loss rate and implemented it into the public version of CMAQv52. In Gantt et al. (2017), the impact of the simple first order loss rate as well as the full halogen chemistry without photochemical reactions of higher iodine oxides over the continental United States was examined using finer horizontal grids of the regional domain and boundary conditions from the hemispheric domain with and without marine halogen chemistry. The boundary conditions obtained with the halogen chemistry as well as the simple halogen chemistry reduces ozone along the coast where CMAQ typically overpredicts the concentrations. Development of halogen chemistry in CMAQ has continued with the implementation of several heterogeneous reactions of bromine and iodine species, revised reactions of higher iodine oxides, and a refined marine halogen emissions inventory. Our latest version of halogen chemistry with photochemical reactions of higher iodine oxides reduces ozone by 23% over the seawater. This presentation will discuss the previous and ongoing implementation of revised halogen

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

    PubMed

    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.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ombaka, L.M.; Ndungu, P.G.; Department of Applied Chemistry, Doornfontein Campus, University of Johannesburg, P.O. Box 17011, Johannesburg 2028

    Nitrogen-doped carbon nanotubes (N-CNTs) have been synthesized at 850 °C via a CVD deposition technique by use of three ferrocenyl derivative catalysts, i.e. para-CN, -CF{sub 3} and -Cl substituted-phenyl rings. The synthesized catalysts have been characterized by NMR, IR, HR-MS and XRD. The XRD analysis of the para-CF{sub 3} catalyst indicates that steric factors influence the X-ray structure of 1,1′-ferrocenylphenyldiacrylonitriles. Acetonitrile or pyridine was used as carbon and nitrogen sources to yield mixtures of N-CNTs and carbon spheres (CS). The N-CNTs obtained from the para-CF{sub 3} catalysts, in pyridine, have the highest nitrogen-doping level, show a helical morphology and aremore » less thermally stable compared with those synthesized by use of the para-CN and -Cl as catalyst. This suggests that fluorine heteroatoms enhance nitrogen-doping in N-CNTs and formation of helical-N-CNTs (H-N-CNTs). The para-CF{sub 3} and para-Cl catalysts in acetonitrile yielded iron-filled N-CNTs, indicating that halogens promote encapsulation of iron into the cavity of N-CNT. The use of acetonitrile, as carbon and nitrogen source, with the para-CN and -Cl as catalysts also yielded a mixture of N-CNTs and carbon nanofibres (CNFs), with less abundance of CNFs in the products obtained using para-Cl catalysts. However, para-CF{sub 3} catalyst in acetonitrile gave N-CNTs as the only shaped carbon nanomaterials. - Graphical abstract: Graphical abstract showing the synthesis of N-CNTs using halogenated-ferrocenyl derivatives as catalyst with pyridine or acetonitrile as nitrogen and carbon sources via the chemical vapour deposition technique. - Highlights: • N-CNTs were synthesized from halogenated ferrocenyl catalysts. • Halogenated catalysts promote nitrogen-doping and pyridinic nitrogen in N-CNTs. • Halogenated catalysts facilitate iron filling of N-CNTs.« less

  10. Regulated and unregulated halogenated disinfection byproduct formation from chlorination of saline groundwater.

    PubMed

    Szczuka, Aleksandra; Parker, Kimberly M; Harvey, Cassandra; Hayes, Erin; Vengosh, Avner; Mitch, William A

    2017-10-01

    Coastal utilities exploiting mildly saline groundwater (<150 mg/L chloride) may be challenged by disinfection byproduct (DBP) formation, a concern likely to increase with sea-level rise. Groundwater from North Carolina coastal aquifers is characterized by large variations in concentrations of halides (bromide up to 10,600 μg/L) and dissolved organic carbon (up to 5.7 mg-C/L). Formation of 33 regulated and unregulated halogenated DBPs, including trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles, haloacetamides, and haloacetaldehydes, was measured after simulated chlorination of 24 coastal North Carolina groundwater samples under typical chlorination conditions. Results of chlorination simulation show that THM levels exceeded the Primary Maximum Contaminant Levels in half of the chlorinated samples. Addition of halides to a low salinity groundwater (110 mg/L chloride) indicated that elevated bromide triggered DBP formation, but chloride was not a critical factor for their formation. DBP speciation, but not overall molar formation, was strongly correlated with bromide variations in the groundwater. THMs and HAAs dominated the measured halogenated DBPs on a mass concentration basis. When measured concentrations were weighted by metrics of toxic potency, haloacetonitriles, and to a lesser degree, haloacetaldehydes and HAAs, were the predominant contributors to calculated DBP-associated toxicity. For some samples exhibiting elevated ammonia concentrations, the addition of chlorine to form chloramines in situ significantly reduced halogenated DBP concentrations and calculated toxicity. HAAs dominated the calculated toxicity of chloraminated waters. Reverse osmosis treatment of saline groundwater (chloride >250 mg/L) can reduce DBP formation by removing halides and organic precursors. However, we show that in a case where reverse osmosis permeate is blended with a separate raw groundwater, the residual bromide level in the permeate could still exceed

  11. Quantitative structure-activity relationships for primary aerobic biodegradation of organic chemicals in pristine surface waters: starting points for predicting biodegradation under acclimatization.

    PubMed

    Nolte, Tom M; Pinto-Gil, Kevin; Hendriks, A Jan; Ragas, Ad M J; Pastor, Manuel

    2018-01-24

    Microbial biomass and acclimation can affect the removal of organic chemicals in natural surface waters. In order to account for these effects and develop more robust models for biodegradation, we have compiled and curated removal data for un-acclimated (pristine) surface waters on which we developed quantitative structure-activity relationships (QSARs). Global analysis of the very heterogeneous dataset including neutral, anionic, cationic and zwitterionic chemicals (N = 233) using a random forest algorithm showed that useful predictions were possible (Q ext 2 = 0.4-0.5) though relatively large standard errors were associated (SDEP ∼0.7). Classification of the chemicals based on speciation state and metabolic pathway showed that biodegradation is influenced by the two, and that the dependence of biodegradation on chemical characteristics is non-linear. Class-specific QSAR analysis indicated that shape and charge distribution determine the biodegradation of neutral chemicals (R 2 ∼ 0.6), e.g. through membrane permeation or binding to P450 enzymes, whereas the average biodegradation of charged chemicals is 1 to 2 orders of magnitude lower, for which degradation depends more directly on cellular uptake (R 2 ∼ 0.6). Further analysis showed that specific chemical classes such as peptides and organic halogens are relatively less biodegradable in pristine surface waters, resulting in the need for the microbial consortia to acclimate. Additional literature data was used to verify an acclimation model (based on Monod-type kinetics) capable of extrapolating QSAR predictions to acclimating conditions such as in water treatment, downstream lakes and large rivers under μg L -1 to mg L -1 concentrations. The framework developed, despite being based on multiple assumptions, is promising and needs further validation using experimentation with more standardised and homogenised conditions as well as adequate characterization of the inoculum used.

  12. Halogen-Adatom Mediated Phase Transition of Two-Dimensional Molecular Self-Assembly on a Metal Surface.

    PubMed

    Niu, Tianchao; Wu, Jinge; Ling, Faling; Jin, Shuo; Lu, Guanghong; Zhou, Miao

    2018-01-09

    Construction of tunable and robust two-dimensional (2D) molecular arrays with desirable lattices and functionalities over a macroscopic scale relies on spontaneous and reversible noncovalent interactions between suitable molecules as building blocks. Halogen bonding, with active tunability of direction, strength, and length, is ideal for tailoring supramolecular structures. Herein, by combining low-temperature scanning tunneling microscopy and systematic first-principles calculations, we demonstrate novel halogen bonding involving single halogen atoms and phase engineering in 2D molecular self-assembly. On the Au(111) surface, we observed catalyzed dehalogenation of hexabromobenzene (HBB) molecules, during which negatively charged bromine adatoms (Br δ- ) were generated and participated in assembly via unique C-Br δ+ ···Br δ- interaction, drastically different from HBB assembly on a chemically inert graphene substrate. We successfully mapped out different phases of the assembled superstructure, including densely packed hexagonal, tetragonal, dimer chain, and expanded hexagonal lattices at room temperature, 60 °C, 90 °C, and 110 °C, respectively, and the critical role of Br δ- in regulating lattice characteristics was highlighted. Our results show promise for manipulating the interplay between noncovalent interactions and catalytic reactions for future development of molecular nanoelectronics and 2D crystal engineering.

  13. The effect of varying halogen substituent patterns on the cytochrome P450 catalysed dehalogenation of 4-halogenated anilines to 4-aminophenol metabolites.

    PubMed

    Cnubben, N H; Vervoort, J; Boersma, M G; Rietjens, I M

    1995-05-11

    The cytochrome P450 catalysed biotransformation of 4-halogenated anilines was studied in vitro with special emphasis on the dehalogenation to 4-aminophenol metabolites. The results demonstrated that a fluorine substituent at the C4 position was more easily eliminated from the aromatic ring than a chloro-, bromo- or iodo-substituent. HPLC analysis of in vitro biotransformation patterns revealed that the dehalogenation of the C4-position was accompanied by formation of non-halogenated 4-aminophenol, without formation of NIH-shifted metabolites. Changes in the apparent Vmax for the microsomal oxidative dehalogenation appeared to correlate with the electronegativity of the halogen substituent at C4, the fluorine substituent being the one most easily eliminated. A similar decrease in the rate of dehalogenation from a fluoro- to a chloro- to a bromo- to an iodo-substituent was observed in a system with purified reconstituted cytochrome P450 IIB1, in a tertiair butyl hydroperoxide supported microsomal cytochrome P450 system as well as in a system with microperoxidase 8. This microperoxidase 8 is a haem-based mini-enzyme without a substrate binding site, capable of catalysing cytochrome P450-like reaction chemistry. Together, these results excluded the possibility that the difference in the rate of dehalogenation with a varying C4-halogen substituent arose from a change in the contribution of cytochrome P450 enzymes involved in oxidative dehalogenation with a change in the halogen substituent. Rather, they strongly suggested that the difference was indeed due to an intrinsic electronic parameter of the various C4 halogenated anilines dependent on the type of halogen substituent. Additional in vitro experiments with polyfluorinated anilines demonstrated that elimination of the C4-fluorine substituent became more difficult upon the introduction of additional electron withdrawing fluorine substituents in the aniline-ring. 19F-NMR analysis of the metabolite patterns showed

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

    PubMed

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

    2017-08-01

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

  15. A Halogen-Containing Stilbene Derivative from the Leaves of Cajanus cajan that Induces Osteogenic Differentiation of Human Mesenchymal Stem Cells.

    PubMed

    Cai, Jia-Zhong; Tang, Rong; Ye, Gui-Fu; Qiu, Sheng-Xiang; Zhang, Nen-Ling; Hu, Ying-Jie; Shen, Xiao-Ling

    2015-06-11

    A new natural halogen-containing stilbene derivative was isolated from the leaves of Cajanus cajan (L.) Millsp. and identified as 3-O-(3-chloro-2-hydroxyl-propanyl)-longistylin A by comprehensive spectroscopic and chemical analysis, and named cajanstilbene H (1). It is the first halogen-containing stilbene derivative found from plants. In human mesenchymal stem cells (hMSC) from bone marrow, 1 did not promote cell proliferation, but distinctly enhanced osteogenic differentiation of hMSC in time- and dose-dependent manners. In six human cancer cell lines, 1 showed a moderate inhibitory effect on cell proliferation, with IC50 values of 21.42-25.85 μmol·L(-1).

  16. 40 CFR 721.2140 - Carbo-poly-cycli-col azo-alkyl-aminoalkyl-carbo-mono-cyclic ester, halogen acid salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Carbo-poly-cycli-col azo-alkyl-aminoalkyl-carbo-mono-cyclic ester, halogen acid salt. 721.2140 Section 721.2140 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specifi...

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

    PubMed

    Pan, Yang; Zhang, Xiangru

    2013-02-05

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

  18. Novel Halogenated Pyrazine-Based Chalcones as Potential Antimicrobial Drugs.

    PubMed

    Kucerova-Chlupacova, Marta; Vyskovska-Tyllova, Veronika; Richterova-Finkova, Lenka; Kunes, Jiri; Buchta, Vladimir; Vejsova, Marcela; Paterova, Pavla; Semelkova, Lucia; Jandourek, Ondrej; Opletalova, Veronika

    2016-10-27

    Chalcones, i.e., compounds with the chemical pattern of 1,3-diphenylprop-2-en-1-ones, exert a wide range of bio-activities, e.g., antioxidant, anti-inflammatory, anticancer, anti-infective etc. Our research group has been focused on pyrazine analogues of chalcones; several series have been synthesized and tested in vitro on antifungal and antimycobacterial activity. The highest potency was exhibited by derivatives with electron withdrawing groups (EWG) in positions 2 and 4 of the ring B. As halogens also have electron withdrawing properties, novel halogenated derivatives were prepared by Claisen-Schmidt condensation. All compounds were submitted for evaluation of their antifungal and antibacterial activity, including their antimycobacterial effect. In the antifungal assay against eight strains of selected fungi, growth inhibition of Candida glabrata and Trichophyton interdigitale (formerly T. mentagrophytes ) was shown by non-alkylated derivatives with 2-bromo or 2-chloro substitution. In the panel of selected bacteria, 2-chloro derivatives showed the highest inhibitory effect on Staphylococcus sp. In addition, all products were also screened for their antimycobacterial activity against Mycobacterium tuberculosis H37RV My 331/88, M. kansasii My 235/80, M. avium 152/80 and M. smegmatis CCM 4622. Some of the examined compounds, inhibited growth of M. kansasii and M. smegmatis with minimum inhibitory concentrations (MICs) comparable with those of isoniazid.

  19. Double-chamber electrode for spectrochemical determination of chlorine and other halogens

    USGS Publications Warehouse

    de Paiva, Azevedo; Specht, A.W.; Harner, R.S.

    1954-01-01

    A double-chamber, graphite electrode, suitable for d.c. arc determination of halogens by means of the alkaline earth halide bands, is described. An upper chamber holds the alkaline earth compound and an interconnected, lower chamber holds the halogen compound. This arrangement assures that there will be an abundance of alkaline earths in the arc by the time the halogen is volatilized from the lower chamber, and thereby promotes maximum emission of the alkaline earth halide bands. ?? 1954.

  20. Halogenated organic pollutants in marine biota from the Xuande Atoll, South China Sea: Levels, biomagnification and dietary exposure.

    PubMed

    Sun, Yu-Xin; Hu, Yong-Xia; Zhang, Zai-Wang; Xu, Xiang-Rong; Li, Heng-Xiang; Zuo, Lin-Zi; Zhong, Yi; Sun, Hong; Mai, Bi-Xian

    2017-05-15

    Six marine biota species were collected from the Xuande Atoll, South China Sea to investigate the bioaccumulation of dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE) and dechlorane plus (DP). Pike conger (Muraenesox talabonoides) had the highest concentrations of halogenated organic pollutants (HOPs) among the six marine biota species. DDTs were the predominant HOPs, followed by PCBs and PBDEs, with minor contributions of DBDPE and DP. Twenty-one percent of samples had ratios of (DDE+DDD)/ΣDDTs lower than 0.5, implying the presence of fresh DDT inputs in the environment of the Xuande Atoll. The biomagnification factor values for DDTs, PCBs, PBDEs and DP were higher than 1, suggesting biomagnification of these contaminants in the marine food chains. Consumption of seafood from the Xuande Atoll might not subject local residents in the coastal areas of South China to health risks as far as HOPs are concerned. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Deciphering Halogen Competition in Organometallic Halide Perovskite Growth

    DOE PAGES

    Keum, Jong Kahk; Ovchinnikova, Olga S.; Chen, Shiyou; ...

    2016-03-01

    Organometallic halide perovskites (OHPs) hold great promise for next-generation, low-cost optoelectronic devices. During the chemical synthesis and crystallization of OHP thin films a major unresolved question is the competition between multiple halide species (e.g. I-, Cl-, Br-) in the formation of the mixed halide perovskite crystals. Whether Cl- ions are successfully incorporated into the perovskite crystal structure or alternatively, where they are located, is not yet fully understood. Here, in situ X-ray diffraction measurements of crystallization dynamics are combined with ex situ TOF-SIMS chemical analysis to reveal that Br- or Cl- ions can promote crystal growth, yet reactive I- ionsmore » prevent them from incorporating into the lattice of the final perovskite crystal structure. The Cl- ions are located in the grain boundaries of the perovskite films. These findings significantly advance our understanding of the role of halogens during synthesis of hybrid perovskites, and provide an insightful guidance to the engineering of high-quality perovskite films, essential for exploring superior-performance and cost-effective optoelectronic devices.« less

  2. Deciphering Halogen Competition in Organometallic Halide Perovskite Growth

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Keum, Jong Kahk; Ovchinnikova, Olga S.; Chen, Shiyou

    Organometallic halide perovskites (OHPs) hold great promise for next-generation, low-cost optoelectronic devices. During the chemical synthesis and crystallization of OHP thin films a major unresolved question is the competition between multiple halide species (e.g. I-, Cl-, Br-) in the formation of the mixed halide perovskite crystals. Whether Cl- ions are successfully incorporated into the perovskite crystal structure or alternatively, where they are located, is not yet fully understood. Here, in situ X-ray diffraction measurements of crystallization dynamics are combined with ex situ TOF-SIMS chemical analysis to reveal that Br- or Cl- ions can promote crystal growth, yet reactive I- ionsmore » prevent them from incorporating into the lattice of the final perovskite crystal structure. The Cl- ions are located in the grain boundaries of the perovskite films. These findings significantly advance our understanding of the role of halogens during synthesis of hybrid perovskites, and provide an insightful guidance to the engineering of high-quality perovskite films, essential for exploring superior-performance and cost-effective optoelectronic devices.« less

  3. FT-Raman spectroscopy study of organic matrix degradation in nanofilled resin composite.

    PubMed

    Soares, Luís Eduardo Silva; Nahórny, Sídnei; Martin, Airton Abrahão

    2013-04-01

    This in vitro study evaluated the effect of light curing unit (LCU) type, mouthwashes, and soft drink on chemical degradation of a nanofilled resin composite. Samples (80) were divided into eight groups: halogen LCU, HS--saliva (control); HPT--Pepsi Twist®; HLC--Listerine®; HCP--Colgate Plax®; LED LCU, LS--saliva (control); LPT--Pepsi Twist®; LLC--Listerine®; LCP--Colgate Plax®. The degree of conversion analysis and the measure of the peak area at 2,930 cm-1 (organic matrix) of resin composite were done by Fourier-transform Raman spectroscopy (baseline, after 7 and 14 days). The data were subjected to multifactor analysis of variance (ANOVA) at a 95% confidence followed by Tukey's HSD post-hoc test. The DC ranged from 58.0% (Halogen) to 59.3% (LED) without significance. Differences in the peak area between LCUs were found after 7 days of storage in S and PT. A marked increase in the peak intensity of HLC and LLC groups was found. The soft-start light-activation may influence the chemical degradation of organic matrix in resin composite. Ethanol contained in Listerine® Cool Mint mouthwash had the most significant degradation effect. Raman spectroscopy is shown to be a useful tool to investigate resin composite degradation.

  4. Halogenation of cobalt dicarbollide

    DOEpatents

    Hurlburt, Paul K.; Abney, Kent D.; Kinkead, Scott A.

    1997-01-01

    A method for selectively adding chlorine, bromine, or iodine to cobalt dicarbollide anions by means of electrophilic substitution reactions. Halogens are added only to the B10 and B10' positions of the anion. The process involves use of hypohalous acid or N-halosuccinimide or gaseous chlorine in the presence of iron.

  5. EFFECT OF NON-TARGET ORGANICS ON ORGANIC CHEMICAL TRANSPORT

    EPA Science Inventory

    To improve our standard of living, man has synthesized organic compounds for use in products considered essential for life. These compounds are having and will continue to have a significant impact on the terrestrial environment. Understanding organic chemical transport through s...

  6. Halogenated naphthyl methoxy piperidines for mapping serotonin transporter sites

    DOEpatents

    Goodman, Mark M.; Faraj, Bahjat

    1999-01-01

    Halogenated naphthyl methoxy piperidines having a strong affinity for the serotonin transporter are disclosed. Those compounds can be labeled with positron-emitting and/or gamma emitting halogen isotopes by a late step synthesis that maximizes the useable lifeterm of the label. The labeled compounds are useful for localizing serotonin transporter sites by positron emission tomography and/or single photon emission computed tomography.

  7. Halogenated naphthyl methoxy piperidines for mapping serotonin transporter sites

    DOEpatents

    Goodman, M.M.; Faraj, B.

    1999-07-06

    Halogenated naphthyl methoxy piperidines having a strong affinity for the serotonin transporter are disclosed. Those compounds can be labeled with positron-emitting and/or gamma emitting halogen isotopes by a late step synthesis that maximizes the useable lifeterm of the label. The labeled compounds are useful for localizing serotonin transporter sites by positron emission tomography and/or single photon emission computed tomography.

  8. RESIDUAL RISK ASSESSMENT: HALOGENATED SOLVENTS

    EPA Science Inventory

    This source category previously subjected to a technology-based standard will be examined to determine if health or ecological risks are significant enough to warrant further regulation for Halogenated Solvent Degreasing Facilities. These assessments utilize existing models and d...

  9. Halogen Radicals Promote the Photodegradation of Microcystins in Estuarine Systems.

    PubMed

    Parker, Kimberly M; Reichwaldt, Elke S; Ghadouani, Anas; Mitch, William A

    2016-08-16

    The transport of microcystin, a hepatotoxin produced by cyanobacteria (e.g., Microcystis aeruginosa), to estuaries can adversely affect estuarine and coastal ecosystems. We evaluated whether halogen radicals (i.e., reactive halogen species (RHS)) could significantly contribute to microcystin photodegradation during transport within estuaries. Experiments in synthetic and natural water samples demonstrated that the presence of seawater halides increased quantum yields for microcystin indirect photodegradation by factors of 3-6. Additional experiments indicated that photoproduced RHS were responsible for this effect. Despite the fact that dissolved organic matter (DOM) concentrations decreased in more saline waters, the calculated photochemical half-life of microcystin decreased 6-fold with increasing salinity along a freshwater-estuarine transect due to the halide-associated increase in quantum yield. Modeling of microcystin photodegradation along this transect indicated that the time scale for RHS-mediated microcystin photodegradation is comparable to the time scale of transport. Microcystin concentrations decline by ∼98% along the transect when considering photodegradation by RHS, but only by ∼54% if this pathway were ignored. These results suggest the importance of considering RHS-mediated photodegradation in future models of microcystin fate in freshwater-estuarine systems.

  10. Dehalogenation of persistent halogenated organic compounds: A review of computational studies and quantitative structure-property relationships.

    PubMed

    Luo, Jin; Hu, Jiwei; Wei, Xionghui; Fu, Liya; Li, Lingyun

    2015-07-01

    Dehalogenation is one of the highly important degradation reactions for halogenated organic compounds (HOCs) in the environment, which is also being developed as a potential type of the remediation technologies. In combination with the experimental results, intensive efforts have recently been devoted to the development of efficient theoretical methodologies (e.g. multi-scale simulation) to investigate the mechanisms for dehalogenation of HOCs. This review summarizes the structural characteristics of neutral molecules, anionic species and excited states of HOCs as well as their adsorption behavior on the surface of graphene and the Fe cluster. It discusses the key physiochemical properties (e.g. frontier orbital energies and thermodynamic properties) calculated at various levels of theory (e.g. semiempirical, ab initio, density functional theory (DFT) and the periodic DFT) as well as their connections to the reactivity and reaction pathway for the dehalogenation. This paper also reviews the advances in the linear and nonlinear quantitative structure-property relationship models for the dehalogenation kinetics of HOCs and in the mathematical modeling of the dehalogenation processes. Furthermore, prospects of further expansion and exploration of the current research fields are described in this article. Published by Elsevier Ltd.

  11. Molecular Signature of Organic Carbon Along a Salinity Gradient in Suwannee River Plume

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Bianchi, T. S.; Ward, N. D.; Arellano, A. R.; Paša-Tolić, L.; Tolic, N.; Kuo, L. J.

    2016-12-01

    Humic and fulvic acid isolates from Suwannee River dissolved organic matter (DOM) have served as reference standards for the International Humic Substances Society (IHSS) for many decades. The large database on Suwannee DOM provides an excellent framework to further expand the application of Fourier transform ion cyclotron mass spectrometry (FT-ICR-MS) in characterizing the chemical composition of aquatic DOM. In this study, we examined the DOM signature of the lower Suwannee River and plume region at 5 stations along a salinity gradient (0 to 28) using FT-ICR-MS. The chemical characteristics of DOM show distinct differences across this steep salinity gradient. In general, samples collected from the coastal station have lower carbon number and are less aromatic. Molecular level analysis reveals that the magnitude weighted proportion of lipids increased as salinity increased. Interestingly, a similar trend was observed for lignin-like compounds. Target quantification of lignin-phenols showed that while the concentrations of these compounds were lower at the coastal station, the DOC-normalized concentrations were not significantly different between the river and coastal stations. In addition to traditional DOM moieties, we identified for the first time, halogenated organic compounds (HOC). We observed more chlorinated compounds in DOM and increased Cl/C as salinity increased. A relatively high proportion of halogenated lipids (compared to non-halogenated) were observed in the total pool of HOC across all stations. Although not significant in relative proportion, halogenated lignin-like compounds were the most abundant HOC moieties in our samples. CO2 concentrations decreased and became more 13C-enriched along the salinity gradient, ranging from 3,990 ppm (13CO2 = -17.3‰) at salinity 0 to 520 ppm (13CO2 = -7.5‰) at salinity 28, indicating high levels of DOM degradation in the river and a shift to primary production in the marine receiving waters, which is

  12. Halogenation of cobalt dicarbollide

    DOEpatents

    Hurlburt, P.K.; Abney, K.D.; Kinkead, S.A.

    1997-05-20

    A method for selectively adding chlorine, bromine, or iodine to cobalt dicarbollide anions by means of electrophilic substitution reactions. Halogens are added only to the B10 and B10{prime} positions of the anion. The process involves use of hypohalous acid or N-halosuccinimide or gaseous chlorine in the presence of iron. 1 fig.

  13. Do complex matrices modify the sorptive properties of polydimethylsiloxane (PDMS) for non-polar organic chemicals?

    PubMed

    Jahnke, Annika; Mayer, Philipp

    2010-07-16

    The partitioning of non-polar analytes into the silicone polydimethylsiloxane (PDMS) is the basis for many analytical approaches such as solid phase microextraction (SPME), stir bar sorptive extraction (SBSE) and environmental passive sampling. Recently, the methods have been applied to increasingly complex sample matrices. The present work investigated the possible effect of complex matrices on the sorptive properties of PDMS. First, SPME fibers with a 30 microm PDMS coating were immersed in 15 different matrices, including sediment, suspensions of soil and humic substances, mayonnaise, meat, fish, olive oil and fish oil. Second, the surface of the fibers was wiped clean, and together with matrix-free control fibers, they were exposed via headspace to 7 non-polar halogenated organic chemicals in spiked olive oil. The fibers were then solvent-extracted, analyzed, and the ratios of the mean concentrations in the matrix-immersed fibers to the control fibers were determined for all matrices. These ratios ranged from 92% to 112% for the four analytes with the highest analytical precision (i.e. polychlorinated biphenyls (PCBs) 3, 28, 52 and brominated diphenyl ether (BDE) 3), and they ranged from 74% to 133% for the other three compounds (i.e. PCBs 101, 105 and gamma-hexachlorocyclohexane (HCH)). We conclude that, for non-polar, hydrophobic chemicals, the sorptive properties of the PDMS were not modified by the diverse investigated media and consequently that PDMS is suited for sampling of these analytes even in highly complex matrices. 2010 Elsevier B.V. All rights reserved.

  14. Metal-organic frameworks for the removal of toxic industrial chemicals and chemical warfare agents.

    PubMed

    Bobbitt, N Scott; Mendonca, Matthew L; Howarth, Ashlee J; Islamoglu, Timur; Hupp, Joseph T; Farha, Omar K; Snurr, Randall Q

    2017-06-06

    Owing to the vast diversity of linkers, nodes, and topologies, metal-organic frameworks can be tailored for specific tasks, such as chemical separations or catalysis. Accordingly, these materials have attracted significant interest for capture and/or detoxification of toxic industrial chemicals and chemical warfare agents. In this paper, we review recent experimental and computational work pertaining to the capture of several industrially-relevant toxic chemicals, including NH 3 , SO 2 , NO 2 , H 2 S, and some volatile organic compounds, with particular emphasis on the challenging issue of designing materials that selectively adsorb these chemicals in the presence of water. We also examine recent research on the capture and catalytic degradation of chemical warfare agents such as sarin and sulfur mustard using metal-organic frameworks.

  15. Investigation of reactive halogens in the Arctic using a mobile instrumental laboratory

    NASA Astrophysics Data System (ADS)

    Custard, K.; Shepson, P. B.; Stephens, C. R.

    2011-12-01

    Custard, K kcustard@purdue.edu Chemistry Department, Purdue University, West Lafayette, IN, USA Shepson, P pshepson@purdue.edu Chemistry Department, Purdue University, West Lafayette, IN, USA Stephens, C thompscr@purdue.edu Chemistry Department, Purdue University, West Lafayette, IN, USA Investigation of the chemistry of reactive halogens in ice-covered regions is important because of its significant impact on atmospheric composition. Halogens in the Arctic react with ozone and gaseous elemental mercury to sometimes completely deplete them from the ambient atmosphere, at least during polar springtime. There is much uncertainty about the sources and concentrations of these atmospheric halogens in the Arctic, particularly with respect to chlorine. To gain a better understanding of them, we have developed a method to simultaneously measure the concentrations of BrOx and ClOx radicals using a flowtube method. The method involves reaction of the halogen atom with a halogenated alkene, to produce a multiply halogenated characteristic ketone product, which is then detected via GC/ECD. The system was deployed at Barrow, AK, using a mobile instrumental laboratory so that measurements could be made from multiple locations along the sea ice. In this paper we will discuss laboratory evaluation of the flowtube method, and present preliminary data from Barrow, AK, during the spring 2011 deployment.

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

    PubMed

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

    2017-05-26

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

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Halogen-free benzoxazine based curable compositions for high TG applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tietze, Roger; Nguyen, Yen-Loan

    The present invention provides a halogen-free curable composition including a benzoxazine monomer, at least one epoxy resin, a catalyst, a toughening agent and a solvent. The halogen-free curable composition is especially suited for use in automobile and aerospace applications since the composition, upon curing, produces a composite having a high glass transition temperature.

  19. Sorption of organic chemicals at biogeochemical interfaces - calorimetric measurements

    NASA Astrophysics Data System (ADS)

    Krüger, J.; Lang, F.; Siemens, J.; Kaupenjohann, M.

    2009-04-01

    Biogeochemical interfaces in soil act as sorbents for organic chemicals, thereby controlling the degradation and mobility of these substances in terrestrial environments. Physicochemical properties of the organic chemicals and the sorbent determine sorptive interactions. We hypothesize that the sorption of hydrophobic organic chemicals ("R-determined" chemicals) is an entropy-driven partitioning process between the bulk aqueous phase and biogeochemical interface and that the attachment of more polar organic chemicals ("F-determined" chemicals) to mineral surfaces is due to electrostatic interactions and ligand exchange involving functional groups. In order to determine thermodynamic parameters of sorbate/sorbent interactions calorimetric titration experiments have been conducted at 20˚ C using a Nanocalorimeter (TAM III, Thermometric). Solutions of different organic substances ("R-determined" chemicals: phenanthrene, bisphenol A, "F-determined" chemicals: MCPA, bentazone) with concentrations of 100 mol l-1 were added to suspensions of pure minerals (goethite, muscovite, and kaolinite and to polygalacturonic acid (PGA) as model substance for biofilms in soil. Specific surface, porosity, N and C content, particle size and point of zero charge of the mineral were analyzed to characterize the sorbents. The obtained heat quantities for the initial injection of the organic chemicals to the goethite were 55 and 71 J for bisphenol A and phenanthrene ("R-determined representatives") and 92 and 105 J for MCPA and bentazone ("F-determined" representatives). Further experiments with muscovite, kaolinite and PGA are in progress to determine G and H of the adsorption process.

  20. Halogen bonding (X-bonding): A biological perspective

    PubMed Central

    Scholfield, Matthew R; Zanden, Crystal M Vander; Carter, Megan; Ho, P Shing

    2013-01-01

    The concept of the halogen bond (or X-bond) has become recognized as contributing significantly to the specificity in recognition of a large class of halogenated compounds. The interaction is most easily understood as primarily an electrostatically driven molecular interaction, where an electropositive crown, or σ-hole, serves as a Lewis acid to attract a variety of electron-rich Lewis bases, in analogous fashion to a classic hydrogen bonding (H-bond) interaction. We present here a broad overview of X-bonds from the perspective of a biologist who may not be familiar with this recently rediscovered class of interactions and, consequently, may be interested in how they can be applied as a highly directional and specific component of the molecular toolbox. This overview includes a discussion for where X-bonds are found in biomolecular structures, and how their structure–energy relationships are studied experimentally and modeled computationally. In total, our understanding of these basic concepts will allow X-bonds to be incorporated into strategies for the rational design of new halogenated inhibitors against biomolecular targets or toward molecular engineering of new biological-based materials. PMID:23225628

  1. Process for oxidation of hydrogen halides to elemental halogens

    DOEpatents

    Lyke, Stephen E.

    1992-01-01

    An improved process for generating an elemental halogen selected from chlorine, bromine or iodine, from a corresponding hydrogen halide by absorbing a molten salt mixture, which includes sulfur, alkali metals and oxygen with a sulfur to metal molar ratio between 0.9 and 1.1 and includes a dissolved oxygen compound capable of reacting with hydrogen halide to produce elemental halogen, into a porous, relatively inert substrate to produce a substrate-supported salt mixture. Thereafter, the substrate-supported salt mixture is contacted (stage 1) with a hydrogen halide while maintaining the substrate-supported salt mixture during the contacting at an elevated temperature sufficient to sustain a reaction between the oxygen compound and the hydrogen halide to produce a gaseous elemental halogen product. This is followed by purging the substrate-supported salt mixture with steam (stage 2) thereby recovering any unreacted hydrogen halide and additional elemental halogen for recycle to stage 1. The dissolved oxygen compound is regenerated in a high temperature (stage 3) and an optical intermediate temperature stage (stage 4) by contacting the substrate-supported salt mixture with a gas containing oxygen whereby the dissolved oxygen compound in the substrate-supported salt mixture is regenerated by being oxidized to a higher valence state.

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

    PubMed

    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.

  3. A metagenomic-based survey of microbial (de)halogenation potential in a German forest soil

    PubMed Central

    Weigold, Pascal; El-Hadidi, Mohamed; Ruecker, Alexander; Huson, Daniel H.; Scholten, Thomas; Jochmann, Maik; Kappler, Andreas; Behrens, Sebastian

    2016-01-01

    In soils halogens (fluorine, chlorine, bromine, iodine) are cycled through the transformation of inorganic halides into organohalogen compounds and vice versa. There is evidence that these reactions are microbially driven but the key enzymes and groups of microorganisms involved are largely unknown. Our aim was to uncover the diversity, abundance and distribution of genes encoding for halogenating and dehalogenating enzymes in a German forest soil by shotgun metagenomic sequencing. Metagenomic libraries of three soil horizons revealed the presence of genera known to be involved in halogenation and dehalogenation processes such as Bradyrhizobium or Pseudomonas. We detected a so far unknown diversity of genes encoding for (de)halogenating enzymes in the soil metagenome including specific and unspecific halogenases as well as metabolic and cometabolic dehalogenases. Genes for non-heme, no-metal chloroperoxidases and haloalkane dehalogenases were the most abundant halogenase and dehalogenase genes, respectively. The high diversity and abundance of (de)halogenating enzymes suggests a strong microbial contribution to natural halogen cycling. This was also confirmed in microcosm experiments in which we quantified the biotic formation of chloroform and bromoform. Knowledge on microorganisms and genes that catalyze (de)halogenation reactions is critical because they are highly relevant to industrial biotechnologies and bioremediation applications. PMID:27353292

  4. Density functional IR, Raman, and VCD spectra of halogen substituted β-lactams

    NASA Astrophysics Data System (ADS)

    Rode, Joanna E.; Dobrowolski, Jan Cz.

    2003-06-01

    Halogenoazetidinones are important as synthetic intermediates for preparation of halogen β-lactam (2-azetidinone) antibiotics and as building blocks for carbohydrates and amino acids. In this paper, we consider the influence of the halogen atom, substituted at the C4 position of the 2-azetidinone ring, on the geometry, IR, Raman, and vibrational circular dichroism spectra. The vibrational spectra were calculated for the chiral 4-( R)-X-2-azetidinone (X=F, Cl or Br) molecules at the B3PW91/aug-cc-pVTZ level. It was shown that the geometry of the molecules studied do not change much upon the change of the halogen atom. In case of the vibrational spectra, the position but even more the intensities depend strongly on the kind of halogen substituent.

  5. Photocrystallographic observation of halide-bridged intermediates in halogen photoeliminations.

    PubMed

    Powers, David C; Anderson, Bryce L; Hwang, Seung Jun; Powers, Tamara M; Pérez, Lisa M; Hall, Michael B; Zheng, Shao-Liang; Chen, Yu-Sheng; Nocera, Daniel G

    2014-10-29

    Polynuclear transition metal complexes, which frequently constitute the active sites of both biological and chemical catalysts, provide access to unique chemical transformations that are derived from metal-metal cooperation. Reductive elimination via ligand-bridged binuclear intermediates from bimetallic cores is one mechanism by which metals may cooperate during catalysis. We have established families of Rh2 complexes that participate in HX-splitting photocatalysis in which metal-metal cooperation is credited with the ability to achieve multielectron photochemical reactions in preference to single-electron transformations. Nanosecond-resolved transient absorption spectroscopy, steady-state photocrystallography, and computational modeling have allowed direct observation and characterization of Cl-bridged intermediates (intramolecular analogues of classical ligand-bridged intermediates in binuclear eliminations) in halogen elimination reactions. On the basis of these observations, a new class of Rh2 complexes, supported by CO ligands, has been prepared, allowing for the isolation and independent characterization of the proposed halide-bridged intermediates. Direct observation of halide-bridged structures establishes binuclear reductive elimination as a viable mechanism for photogenerating energetic bonds.

  6. Noble gas isotopes and halogens in volatile-rich inclusions in diamonds

    NASA Technical Reports Server (NTRS)

    Burgess, Raymond; Turner, Grenville

    1994-01-01

    Application of the (40)Ar-(39)Ar method and noble gas studies to diamonds has increased our understanding of their age relationships to the host kimberlite or lamproite, and of the source and composition of volatile-rich fluids in the upper mantle. The properties of diamond (inert, high mechanical strength and low gas diffusivities) means they are especially useful samples for studying gases trapped deep within the earth (less than 150 km) as they are unlikely to have undergone loss or exchange of entrapped material since formation. Volatile-rich fluids (H2O-CO2) are important agents for metasomatic processes in the upper mantle, and the noble gases and halogens preferentially partition into this phase leading to a strong geochemical coherence between these groups of elements. The abundances of the halogens in the major reservoirs of the Earth shows a marked progression from chlorine, concentrated in the oceans, through to iodine which, through its affinity to organic material, is concentrated mainly in sediments. Abundances in the upper mantle are low. This is particularly true for iodine which is of special interest in view of its potential significance as an indicator of sediment recycling and by way of its link to (129)Xe amomalies in the mantle through the low extinct isotope (129)I. Extensions of the (40)Ar-(39)Ar technique enable measurements of halogens and other elements (K, Ca, Ba, U) by production of noble gas isotopes from these species during neutron irradiation. Samples analyzed in this way include 15 coated stones from an unknown source in Zaire, 3 boarts from the Jwaneng and 1 boart from the Orapa kimberlites, both in Botswana.

  7. Biosensor discovery of thyroxine transport disrupting chemicals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marchesini, Gerardo R.; Meimaridou, Anastasia; Haasnoot, Willem

    2008-10-01

    Ubiquitous chemicals may interfere with the thyroid system that is essential in the development and physiology of vertebrates. We applied a surface plasmon resonance (SPR) biosensor-based screening method for the fast screening of chemicals with thyroxine (T4) transport disrupting activity. Two inhibition assays using the main thyroid hormone transport proteins, T4 binding globulin (TBG) and transthyretin (TTR), in combination with a T4-coated biosensor chip were optimized and automated for screening chemical libraries. The transport protein-based biosensor assays were rapid, high throughput and bioeffect-related. A library of 62 chemicals including the natural hormones, polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs) and metabolites,more » halogenated bisphenol A (BPA), halogenated phenols, pharmaceuticals, pesticides and other potential environmentally relevant chemicals was tested with the two assays. We discovered ten new active compounds with moderate to high affinity for TBG with the TBG assay. Strikingly, the most potent binding was observed with hydroxylated metabolites of the brominated diphenyl ethers (BDEs) BDE 47, BDE 49 and BDE 99, that are commonly found in human plasma. The TTR assay confirmed the activity of previously identified hydroxylated metabolites of PCBs and PBDEs, halogenated BPA and genistein. These results show that the hydroxylated metabolites of the ubiquitous PBDEs not only target the T4 transport at the TTR level, but also, and to a great extent, at the TBG level where most of the T4 in humans is circulating. The optimized SPR biosensor-based transport protein assay is a suitable method for high throughput screening of large libraries for potential thyroid hormone disrupting compounds.« less

  8. Halogenated Natural Products in Dolphins: Brain-Blubber Distribution and Comparison with Halogenated Flame Retardants.

    PubMed

    Barón, E; Hauler, C; Gallistl, C; Giménez, J; Gauffier, P; Castillo, J J; Fernández-Maldonado, C; de Stephanis, R; Vetter, W; Eljarrat, E; Barceló, D

    2015-08-04

    Halogenated natural products (MHC-1, TriBHD, TetraBHD, MeO-PBDEs, Q1, and related PMBPs) and halogenated flame retardants (PBDEs, HBB, Dec 602, Dec 603, and DP) in blubber and brain are reported from five Alboran Sea delphinids (Spain). Both HNPs and HFRs were detected in brain, implying that they are able to surpass the blood-brain barrier and reach the brain, which represents a new finding for some compounds, such as Q1 and PMBPs, MHC-1, TriBHD, TetraBHD, or Dec 603. Moreover, some compounds (TetraBHD, BDE-153, or HBB) presented higher levels in brain than in blubber. This study evidence the high concentrations of HNPs in the marine environment, especially in top predators. It shows the importance of further monitoring these natural compounds and evaluating their potential toxicity, when most studies focus on anthropogenic compounds only. While no bioaccumulation was found for ∑HNPs, ∑HFRs increased significantly with body size for both common and striped dolphins. Studies evaluating BBB permeation mechanisms of these compounds together with their potential neurotoxic effects in dolphins are recommended.

  9. Analysis of organochlorine compounds and extractable organic halogen in three subspecies of ringed seal from northeast Europe

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kostamo, A.; Medvedev, N.; Pellinen, J.

    2000-04-01

    Organochlorine compounds in blubber samples of the ringed seal (Phoca hispida saimensis, P. H. ladogensis, and P. h. hispida) were analyzed in order to estimate the state of pollution in three different water areas in Northeast Europe, namely, Lake Saimaa in Finland, Lake Lodoga, and the White Sea in Russia. Geographic differences in concentrations and in relative concentrations of tri- and tetrachlorocymenes, hexachlorobenzene, {alpha}-HCH, {beta}-HCH, {gamma}-HCH (Lindane), seven polychlorinated biphenyl (PCB) congeners, and p,p{prime}-DDT and its metabolites in ringed seals were compared. Concentrations of chlorinated hydrocarbons varied between the water areas. The highest concentrations were found in Saimaa ringed seals,more » followed by Lodaga ringed seals, and the lowest concentrations were detected in ringed seals from the White Sea. Extractable organic halogen (EOX) concentrations in blubber were also analyzed. The concentrations showed a geographic trend similar to those for the individual compounds identified. In Lakes Ladoga and Saimaa, the concentrations of EOX and chlorinated hydrocarbons in the blubber were dependent on the age and sex of the seals, but no such relationship was observed in samples from the White Sea.« less

  10. Sorption of halogenated phenols and pharmaceuticals to biochar: affecting factors and mechanisms.

    PubMed

    Oh, Seok-Young; Seo, Yong-Deuk

    2016-01-01

    The feasibility of using biochar as a sorbent to remove nine halogenated phenols (2,4-dichlorophenol, 2,4-dibromophenol, 2,4-difluorophenol, 2-chlorophenol, 4-chlorophenol, 2-bromophenol, 4-bromophenol, 2-fluorophenol, and 4-fluorophenol) and two pharmaceuticals (triclosan and ibuprofen) from water was examined through a series of batch experiments. Types of biochar, synthesized using various biomasses including fallen leaves, rice straw, corn stalk, used coffee grounds, and biosolids, were evaluated. Compared to granular activated carbon (GAC), most of the biochar samples did not effectively remove halogenated phenols or pharmaceuticals from water. The increase in pH and deprotonation of phenols in biochar systems may be responsible for its ineffectiveness at this task. When pH was maintained at 4 or 7, the sorption capacity of biochar was markedly increased. Considering maximum sorption capacity and properties of sorbents and sorbates, it appears that the sorption capacity of biochar for halogenated phenols is related to the surface area and carbon content of the biochar and the hydrophobicity of halogenated phenols. In the cases of triclosan and ibuprofen, the sorptive capacities of GAC, graphite, and biochars were also significantly affected by pH, according to the point of zero charge (PZC) of sorbents and deprotonation of the pharmaceuticals. Pyrolysis temperature did not affect the sorption capacity of halogenated phenols or pharmaceuticals. Based on the experimental observations, some biochars are good candidates for removal of halogenated phenols, triclosan, and ibuprofen from water and soil.

  11. The contribution of hydrothermally altered ocean crust to the mantle halogen and noble gas cycles

    NASA Astrophysics Data System (ADS)

    Chavrit, Déborah; Burgess, Ray; Sumino, Hirochika; Teagle, Damon A. H.; Droop, Giles; Shimizu, Aya; Ballentine, Chris J.

    2016-06-01

    Recent studies suggest that seawater-derived noble gases and halogens are recycled into the deep mantle by the subduction of oceanic crust. To understand the processes controlling the availability of halogens and noble gases for subduction, we determined the noble gas elemental and isotopic ratios and halogen (Cl, Br, I) concentrations in 28 igneous samples from the altered oceanic crust (AOC) from 5 ODP sites in the Eastern and Western Pacific Ocean. Crushing followed by heating experiments enabled determination of noble gases and halogens in fluid inclusions and mineral phases respectively. Except for He and Ar, Ne, Kr and Xe isotopic ratios were all air-like suggesting that primary MORB signatures have been completely overprinted by air and/or seawater interaction. In contrast, 3He/4He ratios obtained by crushing indicate that a mantle helium component is still preserved, and 40Ar/36Ar values are affected by radiogenic decay in the mineral phases. The 130Xe/36Ar and 84Kr/36Ar ratios are respectively up to 15 times and 5 times higher than those of seawater and the highest ratios are found in samples affected by low temperature alteration (shallower than 800-900 m sub-basement). We consider three possible processes: (i) adsorption onto the clays present in the samples; (ii) fluid inclusions with a marine pore fluid composition; and (iii) fractionation of seawater through phase separation caused by boiling. Ninety percent of the Cl, Br and I were released during the heating experiments, showing that halogens are dominantly held in mineral phases prior to subduction. I/Cl ratios vary by 4 orders of magnitude, from 3 × 10-6 to 2 × 10-2. The mean Br/Cl ratio is 30% lower than in MORB and seawater. I/Cl ratios lower than MORB values are attributed to Cl-rich amphibole formation caused by hydrothermal alteration at depths greater than 800-900 m sub-basement together with different extents of I loss during low and high temperature alteration. At shallower depths, I

  12. Non-PBDE halogenated flame retardants in Canadian indoor house dust: sampling, analysis, and occurrence.

    PubMed

    Fan, Xinghua; Kubwabo, Cariton; Rasmussen, Pat E; Wu, Fang

    2016-04-01

    An analytical method was developed for the measurement of 18 novel halogenated flame retardants in house dust. Sample preparation was based on ultrasound-assisted solvent extraction and clean up with solid phase extraction (SPE). Sample extracts were analyzed by gas chromatography-mass spectrometry (GC/MS) operated in electron capture negative ion (ECNI) chemical ionization mode. Baseline data from 351 fresh (active) dust samples collected under the Canadian House Dust Study (CHDS) revealed that five out of 18 target chemicals were present with detection frequencies higher than 90 %. Median (range) concentrations for these five compounds were as follows: 104 (<1.5-13,000) ng/g for 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB), 8.5 (<1.7-2390) ng/g for 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), 10.2 (<1.7-430) ng/g for hexabromobenzene (HBB), 2.9 (<1.2-1410) ng/g for syn-dechlorane plus (syn-DP) and 5.6 (<1.9-1570) ng/g for anti-dechlorane plus (anti-DP). A comparison of two sampling methods in a subset of 40 homes showed significant positive correlations between samples of "active" dust and samples taken directly from the household vacuum cleaner for all target compounds having median values above their corresponding method detection limits (MDLs). In addition, the method was also applied to the analysis of the targeted compounds in National Institute of Standards and Technology (NIST) standard reference material (SRM 2585, organic contaminants in house dust). Results from the current study could contribute to the potential certification of target chemicals in SRM 2585.

  13. Cross-reactivity of Halogenated Platinum Salts

    EPA Science Inventory

    Halogenated platinum (Pt) salts are well-known respiratory sensitizers associated with the development of asthma. People may be exposed to a variety of platinum compounds in different contexts (e.g. occupationally, automobile exhaust). Published reports suggest that sensitizati...

  14. Process for removing halogenated aliphatic and aromatic compounds from petroleum products

    DOEpatents

    Googin, John M.; Napier, John M.; Travaglini, Michael A.

    1983-01-01

    A process for removing halogenated aliphatic and aromatic compounds, e.g., polychlorinated biphenyls, from petroleum products by solvent extraction. The halogenated aliphatic and aromatic compounds are extracted from a petroleum product into a polar solvent by 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.

  15. COSOLVENCY AND SOPRTION OF HYDROPHOBIC ORGANIC CHEMICALS

    EPA Science Inventory

    Sorption of hydrophobic organic chemicals (HOCs) by two soils was measured from mixed solvents containing water plus completely miscible organic solvents (CMOSs) and partially miscible organic solvents (PMOSs). The utility of the log-linear cosolvency model for predicting HOC sor...

  16. Loss of halogens from crystallized and glassy silicic volcanic rocks

    USGS Publications Warehouse

    Noble, D.C.; Smith, V.C.; Peck, L.C.

    1967-01-01

    One hundred and sixty-four F and Cl analyses of silicic welded tuffs and lavas and glass separates are presented. Comparison of the F and Cl contents of crystallized rocks with those of nonhydrated glass and hydrated glassy rocks from the same rock units shows that most of the halogens originally present were lost on crystallization. An average of about half of the F and four-fifths of the Cl originally present was lost. Analyses of hydrated natural glasses and of glassy rocks indicate that in some cases significant amounts of halogens may be removed from or added to hydrated glass through prolonged contact with ground water. The data show that the original halogen contents of the groundmass of a silicic volcanic rock can be reliably determined only from nonhydrated glass. ?? 1967.

  17. Mixing Halogens To Assemble an All-Inorganic Layered Perovskite with Warm White-Light Emission.

    PubMed

    Li, Xianfeng; Wang, Sasa; Zhao, Sangen; Li, Lina; Li, Yanqiang; Zhao, Bingqing; Shen, Yaoguo; Wu, Zhenyue; Shan, Pai; Luo, Junhua

    2018-05-01

    Most of single-component white-light-emitting materials focus on organic-inorganic hybrid perovskites, metal-organic frameworks, as well as all-inorganic semiconductors. In this work, we successfully assembled an all-inorganic layered perovskite by mixing two halogens of distinct ionic radii, namely, Rb 2 CdCl 2 I 2 , which emits "warm" white light with a high color rendering index of 88. To date, Rb 2 CdCl 2 I 2 is the first single-component white-light-emitting material with an all-inorganic layered perovskite structure. Furthermore, Rb 2 CdCl 2 I 2 is thermally highly stable up to 575 K. A series of luminescence measurements show that the white-light emission arises from the lattice deformation, which are closely related to the [CdCl 4 I 2 ] 2- octahedra with high distortion from the distinct ionic radii of Cl and I. The first-principles calculations reveal that both the Cl and I components make significant contributions to the electronic band structures of Rb 2 CdCl 2 I 2 . These findings indicate that mixing halogens is an effective route to design and synthesize new single-component white-light-emitting materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    NASA Technical Reports Server (NTRS)

    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.

  19. Chemical alternatives assessment of different flame retardants - A case study including multi-walled carbon nanotubes as synergist.

    PubMed

    Aschberger, Karin; Campia, Ivana; Pesudo, Laia Quiros; Radovnikovic, Anita; Reina, Vittorio

    2017-04-01

    Flame retardants (FRs) are a diverse group of chemicals used as additives in a wide range of products to inhibit, suppress, or delay ignition and to prevent the spread of fire. Halogenated FRs (HFRs) are widely used because of their low impact on other material properties and the low loading levels necessary to meet the required flame retardancy. Health and environmental hazards associated with some halogenated FRs have driven research for identifying safer alternatives. A variety of halogen-free FRs are available on the market, including organic (phosphorus and nitrogen based chemicals) and inorganic (metals) materials. Multi-walled carbon nanotubes (MWCNT) have been demonstrated to act as an effective/synergistic co-additive in some FR applications and could thereby contribute to reducing the loading of FRs in products and improving their performance. As part of the FP7 project DEROCA we carried out a chemical alternatives assessment (CAA). This is a methodology for identifying, comparing and selecting safer alternatives to chemicals of concern based on criteria for categorising human and environmental toxicity as well as environmental fate. In the project we assessed the hazard data of different halogen-free FRs to be applied in 5 industrial and consumer products and here we present the results for MWCNT, aluminium diethylphosphinate, aluminium trihydroxide, N-alkoxy hindered amines and red phosphorus compared to the HFR decabromodiphenylether. We consulted the REACH guidance, the criteria of the U.S.-EPA Design for Environment (DfE) and the GreenScreen® Assessment to assess and compare intrinsic properties affecting the hazard potential. A comparison/ranking of exposure reference values such as Derived No Effect Levels (DNELs) showed that FRs of concern are not identified by a low DNEL. A comparison based on hazard designations according to the U.S.-EPA DfE and GreenScreen® for human health endpoints, aquatic toxicity and environmental fate showed that the

  20. Do Halogen–Hydrogen Bond Donor Interactions Dominate the Favorable Contribution of Halogens to Ligand–Protein Binding?

    PubMed Central

    2017-01-01

    Halogens are present in a significant number of drugs, contributing favorably to ligand–protein binding. Currently, the contribution of halogens, most notably chlorine and bromine, is largely attributed to halogen bonds involving favorable interactions with hydrogen bond acceptors. However, we show that halogens acting as hydrogen bond acceptors potentially make a more favorable contribution to ligand binding than halogen bonds based on quantum mechanical calculations. In addition, bioinformatics analysis of ligand–protein crystal structures shows the presence of significant numbers of such interactions. It is shown that interactions between halogens and hydrogen bond donors (HBDs) are dominated by perpendicular C–X···HBD orientations. Notably, the orientation dependence of the halogen–HBD (X–HBD) interactions is minimal over greater than 100° with favorable interaction energies ranging from −2 to −14 kcal/mol. This contrasts halogen bonds in that X–HBD interactions are substantially more favorable, being comparable to canonical hydrogen bonds, with a smaller orientation dependence, such that they make significant, favorable contributions to ligand–protein binding and, therefore, should be actively considered during rational ligand design. PMID:28657759

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

    PubMed

    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.

  2. 40 CFR 414.60 - Applicability; description of the commodity organic chemicals subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... commodity organic chemicals subcategory. 414.60 Section 414.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Commodity Organic Chemicals § 414.60 Applicability; description of the commodity organic chemicals...

  3. 40 CFR 414.80 - Applicability; description of the specialty organic chemicals subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... specialty organic chemicals subcategory. 414.80 Section 414.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Specialty Organic Chemicals § 414.80 Applicability; description of the specialty organic chemicals...

  4. 40 CFR 414.80 - Applicability; description of the specialty organic chemicals subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... specialty organic chemicals subcategory. 414.80 Section 414.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Specialty Organic Chemicals § 414.80 Applicability; description of the specialty organic chemicals...

  5. 40 CFR 414.80 - Applicability; description of the specialty organic chemicals subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... specialty organic chemicals subcategory. 414.80 Section 414.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Specialty Organic Chemicals § 414.80 Applicability; description of the specialty organic chemicals...

  6. 40 CFR 414.60 - Applicability; description of the commodity organic chemicals subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... commodity organic chemicals subcategory. 414.60 Section 414.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Commodity Organic Chemicals § 414.60 Applicability; description of the commodity organic chemicals...

  7. 40 CFR 414.60 - Applicability; description of the commodity organic chemicals subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... commodity organic chemicals subcategory. 414.60 Section 414.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Commodity Organic Chemicals § 414.60 Applicability; description of the commodity organic chemicals...

  8. 40 CFR 414.60 - Applicability; description of the commodity organic chemicals subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... commodity organic chemicals subcategory. 414.60 Section 414.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Commodity Organic Chemicals § 414.60 Applicability; description of the commodity organic chemicals...

  9. 40 CFR 414.80 - Applicability; description of the specialty organic chemicals subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... specialty organic chemicals subcategory. 414.80 Section 414.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Specialty Organic Chemicals § 414.80 Applicability; description of the specialty organic chemicals...

  10. 40 CFR 414.60 - Applicability; description of the commodity organic chemicals subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... commodity organic chemicals subcategory. 414.60 Section 414.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Commodity Organic Chemicals § 414.60 Applicability; description of the commodity organic chemicals...

  11. 40 CFR 414.80 - Applicability; description of the specialty organic chemicals subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... specialty organic chemicals subcategory. 414.80 Section 414.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Specialty Organic Chemicals § 414.80 Applicability; description of the specialty organic chemicals...

  12. Evaluating the potential for halogen bonding in ketosteroid isomerase’s oxyanion hole using unnatural amino acid mutagenesis

    PubMed Central

    Kraut, Daniel A; Churchil, Michael J; Dawson, Phillip E

    2009-01-01

    There has recently been an increasing interest in controlling macromolecular conformations and interactions through halogen bonding. Halogen bonds are favorable electrostatic interactions between polarized, electropositive chlorine, bromine or iodine atoms and electronegative atoms such as oxygen or nitrogen. These interactions have been likened to hydrogen bonds both in terms of their favored acceptor molecules, their geometries, and their energetics. We asked whether a halogen bond could replace a hydrogen bond in the oxyanion hole of ketosteroid isomerase, using semi-synthetic enzyme containing para-halogenated phenylalanine derivatives to replace the tyrosine hydrogen bond donor. Formation of a halogen bond to the oxyanion in the transition state would be expected to rescue the effects of mutation to phenylalanine, but all of the halogenated enzymes were comparable in activity to the phenylalanine mutant. We conclude that, at least in this active site, a halogen bond cannot functionally replace a hydrogen bond. PMID:19260691

  13. Synthesis and photophysical properties of halogenated derivatives of (dibenzoylmethanato)boron difluoride

    NASA Astrophysics Data System (ADS)

    Kononevich, Yuriy N.; Surin, Nikolay M.; Sazhnikov, Viacheslav A.; Svidchenko, Evgeniya A.; Aristarkhov, Vladimir M.; Safonov, Andrei A.; Bagaturyants, Alexander A.; Alfimov, Mikhail V.; Muzafarov, Aziz M.

    2017-03-01

    A series of (dibenzoylmethanato)boron difluoride (BF2DBM) derivatives with a halogen atom in one of the phenyl rings at the para-position were synthesized and used to elucidate the effects of changing the attached halogen atom on the photophysical properties of BF2DBM. The room-temperature absorption and fluorescence maxima of fluoro-, chloro-, bromo- and iodo-substituted derivatives of BF2DBM in THF are red-shifted by about 2-10 nm relative to the corresponding peaks of the parent BF2DBM. The fluorescence quantum yields of the halogenated BF2DBMs (except the iodinated derivative) are larger than that of the unsubstituted BF2DBM. All the synthesized compounds are able to form fluorescent exciplexes with benzene and toluene (emission maxima at λem = 433 and 445 nm, respectively). The conformational structure and electronic spectral properties of halogenated BF2DBMs have been modeled by DFT/TDDFT calculations at the PBE0/SVP level of theory. The structure and fluorescence spectra of exciplexes were calculated using the CIS method with empirical dispersion correction.

  14. A Review of Hydrogen/Halogen Flow Cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cho, Kyu Taek; Tucker, Michael C.; Weber, Adam Z.

    Flow batteries provide an energy-storage solution for various grid-related stability and service issues that arise as renewable-energy-generation technologies are adopted. Among the most promising flow-battery systems are those using hydrogen/halogen redox couples, which promise the possibility of meeting the cost target of the US Department of Energy (DOE), due to their fast and reversible kinetics and low materials cost. However, significant critical issues and barriers for their adoption remain. In this review of halogen/hydrogen systems, technical and performance issues, and research and development progress are reviewed. The information in this review can be used as a technical guide for researchmore » and development of related redox-flow-battery systems and other electrochemical technologies.« less

  15. Method and apparatus for detecting halogenated hydrocarbons

    DOEpatents

    Monagle, Matthew; Coogan, John J.

    1997-01-01

    A halogenated hydrocarbon (HHC) detector is formed from a silent discharge (also called a dielectric barrier discharge) plasma generator. A silent discharge plasma device receives a gas sample that may contain one or more HHCs and produces free radicals and excited electrons for oxidizing the HHCs in the gas sample to produce water, carbon dioxide, and an acid including halogens in the HHCs. A detector is used to sensitively detect the presence of the acid. A conductivity cell detector combines the oxidation products with a solvent where dissociation of the acid increases the conductivity of the solvent. The conductivity cell output signal is then functionally related to the presence of HHCs in the gas sample. Other detectors include electrochemical cells, infrared spectrometers, and negative ion mobility spectrometers.

  16. A Review of Hydrogen/Halogen Flow Cells

    DOE PAGES

    Cho, Kyu Taek; Tucker, Michael C.; Weber, Adam Z.

    2016-05-17

    Flow batteries provide an energy-storage solution for various grid-related stability and service issues that arise as renewable-energy-generation technologies are adopted. Among the most promising flow-battery systems are those using hydrogen/halogen redox couples, which promise the possibility of meeting the cost target of the US Department of Energy (DOE), due to their fast and reversible kinetics and low materials cost. However, significant critical issues and barriers for their adoption remain. In this review of halogen/hydrogen systems, technical and performance issues, and research and development progress are reviewed. The information in this review can be used as a technical guide for researchmore » and development of related redox-flow-battery systems and other electrochemical technologies.« less

  17. Organic Chemicals: Angels or Goblins?

    ERIC Educational Resources Information Center

    Ferguson, Lloyd N.

    1978-01-01

    Discusses some of the controversial organic chemical substances such as DDT, Red Dye No. 2, DES, Tris, Laetrile, cyclamate, and saccharin. Concludes that the use of some has to be considered on a benefit/risk ratio. (GA)

  18. Halogens, Barium and Uranium in Mantle Fluid Inclusions

    NASA Astrophysics Data System (ADS)

    Villa, I. M.; Peverelli, V.; Oglialoro, E.; Pettke, D. T.; Frezzotti, M. L.

    2016-12-01

    Halogens are an underexplored geochemical marker. A way to measure halogens at ng/g levels is measuring Ar, Kr and Xe in irradiated samples [1,2]. We derive absolute halogen amounts from rare gas amounts via scapolite monitor SY [2]. Kr-Xe systematics also yield Ba and U concentrations. We combined irradiation with stepheating on carbonate-sulfate-rich fluid inclusions (FI)-bearing xe­no­liths from El Hierro, Canarias: spinel harzburgite XML-7 and spinel dunite XML-1 [3]. Three components are recognized in the rare gas release. (1) Atmospheric surface contamination occurs up to 1000 °C. (2) FI decrepitation by laboratory heating occurs above 1200 °C [4], corresponding to the release of 80,82Kr and 128Xe in the 1200 and 1400 °C steps. Br whole-rock concentrations are 3-8 ng/g; the molar Br/Cl and I/Cl ratios in the harzburgite FI, 9 E-4 resp. 2 E-4, are identical to those in the dunite FI. This sets the halogens in our FI apart from MORB [2]. Halogen-derived rare gases are closely associated to artificial 131Xe from Ba; Ba has a high affinity of for CO2-rich fluids. Daughter minerals in multiphase FI were identified by Raman micro­spectroscopy [4]. The calculated Ba concentrations are 2-6 µg/g. (3) The third component is U-derived 134,136Xe and 86Kr released in a spike at 1000 °C, decoupled from FI. This requires a different carrier than FI, e.g. Ti oxides. As U concentrations are 10-20 pg/g, the U-bearing phase needs to be below a ppm, invisible by petro­graphy. The 136Xe/134Xe ratio > 1 suggests retention of radio­genic Xe. However, analysis of an unirradiated sample detected no radiogenic Xe. It is likely that Xe-U produced in the core of the McMaster reactor (thermal, epithermal and fast neutrons) has a different isotopic composition from that in textbooks, as proposed by [2].[1] Jeffery & Reynolds (1961) J.Geophys. Res. 66, 3582 [2] Kendrick (2012) Chem. Geol. 292, 116 [3] Oglialoro et al (2015) AGU Fall Meeting abstract V21C-3046 [4] Roedder (1965

  19. Process for removing halogenated aliphatic and aromatic compounds from petroleum products

    DOEpatents

    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.

  20. 79/81Br nuclear quadrupole resonance spectroscopic characterization of halogen bonds in supramolecular assemblies.

    PubMed

    Cerreia Vioglio, P; Szell, P M J; Chierotti, M R; Gobetto, R; Bryce, D L

    2018-05-28

    Despite the applicability of solid-state NMR to study the halogen bond, the direct NMR detection of 79/81 Br covalently bonded to carbon remains impractical due to extremely large spectral widths, even at ultra-high magnetic fields. In contrast, nuclear quadrupole resonance (NQR) offers comparatively sharp resonances. Here, we demonstrate the abilities of 79/81 Br NQR to characterize the electronic changes in the C-Br···N halogen bonding motifs found in supramolecular assemblies constructed from 1,4-dibromotetrafluorobenzene and nitrogen-containing heterocycles. An increase in the bromine quadrupolar coupling constant is observed, which correlates linearly with the halogen bond distance ( d Br···N ). Notably, 79/81 Br NQR is able to distinguish between two symmetry-independent halogen bonds in the same crystal structure. This approach offers a rapid and reliable indication for the occurrence of a halogen bond, with experimental times limited only by the observation of 79/81 Br NQR resonances.

  1. Assembling supramolecular networks by halogen bonding in coordination polymers driven by 5-bromonicotinic acid

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gu, Jin-Zhong, E-mail: gujzh@lzu.edu.cn; Wu, Jiang; Kirillov, Alexander M.

    2014-05-01

    A series of six coordination compounds ([Zn(5-Brnic){sub 2}]·1.5H{sub 2}O){sub n} (1), [Cd(5-Brnic){sub 2}]{sub n} (2), [Co(5-Brnic){sub 2}(H{sub 2}O){sub 2}]{sub n} (3), [Zn(5-Brnic){sub 2}(H{sub 2}biim)]{sub n} (4), ([Cd(5-Brnic){sub 2}(phen)]·H{sub 2}O){sub n} (5), and [Pb(5-Brnic){sub 2}(phen)] (6) have been generated by the hydrothermal method from the metal(II) nitrates, 5-bromonicotinic acid (5-BrnicH), and an optional ancillary 1,10-phenanthroline (phen) or 2,2′-biimidazole (H{sub 2}biim) ligand. All the products 1–6 have been characterized by IR spectroscopy, elemental, thermal, powder and single-crystal X-ray diffraction analyses. Their 5-bromonicotinate-driven structures vary from the 3D metal-organic framework with the seh-3,5-P21/c topology (in 2) and the 2D interdigitated layers with themore » sql topology (in 1 and 3), to the 1D chains (in 4 and 5) and the 0D discrete monomers (in 6). The 5-bromonicotinate moiety acts as a versatile building block and its tethered bromine atom plays a key role in reinforcing and extending the structures into diverse 3D supramolecular networks via the various halogen bonding Br⋯O, Br⋯Br, and Br⋯π interactions, as well as the N–H⋯O and C–H⋯O hydrogen bonds. The obtained results demonstrate a useful guideline toward engineering the supramolecular architectures in the coordination network assembly under the influence of various halogen bonding interactions. The luminescent (for 1, 2, 4, 5, and 6) and magnetic (for 3) properties have also been studied and discussed in detail. - Graphical abstract: Six coordination compounds driven by 5-bromonicotinic acid have been generated and structurally characterized, revealing diverse metal-organic networks that are further reinforced and extended via various halogen bonding interactions. - Highlights: • 5-Bromonicotinic acid is a versatile ligand for Zn, Cd, Co and Pb derivatives. • Careful selection of co-ligands and metals resulted in different network

  2. Modulation of the fibrillogenesis inhibition properties of two transthyretin ligands by halogenation.

    PubMed

    Cotrina, Ellen Y; Pinto, Marta; Bosch, Lluís; Vilà, Marta; Blasi, Daniel; Quintana, Jordi; Centeno, Nuria B; Arsequell, Gemma; Planas, Antoni; Valencia, Gregorio

    2013-11-27

    The amyloidogenic protein transthyretin (TTR) is thought to aggregate into amyloid fibrils by tetramer dissociation which can be inhibited by a number of small molecule compounds. Our analysis of a series of crystallographic protein-inhibitor complexes has shown no clear correlation between the observed molecular interactions and the in vitro activity of the inhibitors. From this analysis, it emerged that halogen bonding (XB) could be mediating some key interactions. Analysis of the halogenated derivatives of two well-known TTR inhibitors has shown that while flufenamic acid affinity for TTR was unchanged by halogenation, diflunisal gradually improves binding up to 1 order of magnitude after iodination through interactions that can be interpreted as a suboptimal XB (carbonyl Thr106: I...O distance 3.96-4.05 Å; C-I...O angle 152-156°) or as rather optimized van der Waals contacts or as a mixture of both. These results illustrate the potential of halogenation strategies in designing and optimizing TTR fibrillogenesis inhibitors.

  3. Partial separation of halogens during the subduction of oceanic crust

    NASA Astrophysics Data System (ADS)

    Joachim, Bastian; Pawley, Alison; Lyon, Ian; Henkel, Torsten; Clay, Patricia L.; Ruzié, Lorraine; Burgess, Ray; Ballentine, Christopher J.

    2014-05-01

    Incompatible elements, such as halogens, have the potential to act as key tracers for volatile transport processes in Earth and planetary systems. The determination of halogen abundances and ratios in different mantle reservoirs gives us the ability to better understand volatile input mechanisms into the Earth's mantle through subduction of oceanic crust. Halogen partition coefficients were experimentally determined between forsterite, orthopyroxene and silicate melt at pressures ranging from 1.0 to 2.3 GPa and temperatures ranging from 1500-1600°C, thus representing partial melting conditions of the Earth's mantle. Combining our data with results of recent studies (Beyer et al. 2012; Dalou et al. 2012) shows that halogen partitioning between forsterite and melt increases by factors of about 1000 (fluorine) and 100 (chlorine) between 1300°C and 1600°C and does not show any pressure dependence. Chlorine partitioning between orthopyroxene and melt increases by a factor of about 1500 for a temperature increase of 100°C (anywhere between 1300°C and 1600°C), but decreases by a factor of about 1500 for a pressure increase of 1.0 GPa (anywhere between 1.0 GPa and 2.5 GPa). At similar P-T conditions, a comparable effect is observed for the fluorine partitioning behaviour, which increases by 500-fold for a temperature increase of 100°C and decreases with increasing pressure. Halogen abundances in mid-ocean ridge basalts (MORB; F=3-15, Cl=0.5-14ppm) and ocean island basalts (OIB; F=35-65, Cl=21-55 ppm) source regions were estimated by combining our experimentally determined partition coefficients with natural halogen concentrations in oceanic basalts (e.g. Ruzié et al. 2012). The estimated chlorine OIB source mantle concentration is in almost perfect agreement with primitive mantle estimates (Palme and O'Neill 2003). If we expect an OIB source mantle slightly depleted in incompatible elements, this suggests that at least small amounts of chlorine are recycled deep

  4. HYDRODEHALOGENATION OF 1- TO 3-CARBON HALOGENATED ORGANIC COMPOUNDS IN WATER USING A PALLADIUM CATALYST AND HYDROGEN GAS. (R825421)

    EPA Science Inventory

    Supported palladium (Pd) metal catalysts along with H2 gas show
    significant potential as a technology which can provide rapid, on-site
    destruction of halogenated groundwater contaminants. Pd catalyzes the rapid
    hydrodehalogenation of nine 1- to 3-carbon ...

  5. Comment on "Cosmic-ray-driven reaction and greenhouse effect of halogenated molecules: Culprits for atmospheric ozone depletion and global climate change"

    NASA Astrophysics Data System (ADS)

    Müller, Rolf; Grooß, Jens-Uwe

    2014-04-01

    Lu's "cosmic-ray-driven electron-induced reaction (CRE) theory" is based on the assumption that the CRE reaction of halogenated molecules (e.g., chlorofluorocarbons (CFCs), HCl, ClONO2) adsorbed or trapped in polar stratospheric clouds in the winter polar stratosphere is the key step in forming photoactive halogen species that are the cause of the springtime ozone hole. This theory has been extended to a warming theory of halogenated molecules for climate change. In this comment, we discuss the chemical and physical foundations of these theories and the conclusions derived from the theories. First, it is unclear whether the loss rates of halogenated molecules induced by dissociative electron attachment (DEA) observed in the laboratory can also be interpreted as atmospheric loss rates, but even if this were the case, the impact of DEA-induced reactions on polar chlorine activation and ozone loss in the stratosphere is limited. Second, we falsify several conclusions that are reported on the basis of the CRE theory: There is no polar ozone loss in darkness, there is no apparent 11-year periodicity in polar total ozone measurements, the age of air in the polar lower stratosphere is much older than 1-2 years, and the reported detection of a pronounced recovery (by about 20-25%) in Antarctic total ozone measurements by the year 2010 is in error. There are also conclusions about the future development of sea ice and global sea level which are fundamentally flawed because Archimedes' principle is neglected. Many elements of the CRE theory are based solely on correlations between certain datasets which are no substitute for providing physical and chemical mechanisms causing a particular behavior noticeable in observations. In summary, the CRE theory cannot be considered as an independent, alternative mechanism for polar stratospheric ozone loss and the conclusions on recent and future surface temperature and global sea level change do not have a physical basis.

  6. Long-term sorption of halogenated organic chemicals by aquifer material. 1. Equilibrium

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ball, W.P.; Roberts, P.V.

    1991-07-01

    The sorption of tetrachloroethene (PCE) and 1,2,4,5-tetrachlorobenzene (TeCB) was studied on sandy aquifer material from Borden, ON, by using a batch methodology designed to accurately measure sorption over long equilibration periods. Autoclaving was effective in inhibiting biotransformation, and use of fire-sealed glass ampules precluded volatilization losses. Data analysis techniques were developed to accurately account for partitioning to sample headspace and other losses. Sorption isotherms for PCE and TeCB with Borden solids deviated from linearity when a 4-5 order of magnitude range in aqueous concentration was considered. However, in the dilute range (<50 {mu}/l), the deviations from linearity were inconsequential. Themore » sorption of TeCB was approximately 40 times stronger than for PCE, in qualitative accordance with TeCB's approximately 100-fold greater octanol-water partitioning coefficient. For a given solute, the distribution coefficients differed by a factor of 30 among the various size fractions, being greatest for the largest grains. For most Borden solids, the long-term sorption of PCE and TeCB exceeded by more than 1 order of magnitude the predictions of generalized correlations based on hydrophobic partitioning into organic matter. This difference is believed to be partially the result of mineral contributions to sorption, but may also reflect unattainment of equilibrium in previously regressed results - in this study, contact times on the order of tens to hundreds of days were required. For Borden solids, pulverization of solid samples was shown to be a viable expedient to obviate the need for excessively long equilibrations.« less

  7. A linear solvation energy relationship model of organic chemical partitioning to dissolved organic carbon.

    PubMed

    Kipka, Undine; Di Toro, Dominic M

    2011-09-01

    Predicting the association of contaminants with both particulate and dissolved organic matter is critical in determining the fate and bioavailability of chemicals in environmental risk assessment. To date, the association of a contaminant to particulate organic matter is considered in many multimedia transport models, but the effect of dissolved organic matter is typically ignored due to a lack of either reliable models or experimental data. The partition coefficient to dissolved organic carbon (K(DOC)) may be used to estimate the fraction of a contaminant that is associated with dissolved organic matter. Models relating K(DOC) to the octanol-water partition coefficient (K(OW)) have not been successful for many types of dissolved organic carbon in the environment. Instead, linear solvation energy relationships are proposed to model the association of chemicals with dissolved organic matter. However, more chemically diverse K(DOC) data are needed to produce a more robust model. For humic acid dissolved organic carbon, the linear solvation energy relationship predicts log K(DOC) with a root mean square error of 0.43. Copyright © 2011 SETAC.

  8. Quantum descriptors for predictive toxicology of halogenated aliphatic hydrocarbons.

    PubMed

    Trohalaki, S; Pachter, R

    2003-04-01

    In order to improve Quantitative Structure-Activity Relationships (QSARs) for halogenated aliphatics (HA) and to better understand the biophysical mechanism of toxic response to these ubiquitous chemicals, we employ improved quantum-mechanical descriptors to account for HA electrophilicity. We demonstrate that, unlike the lowest unoccupied molecular orbital energy, ELUMO, which was previously used as a descriptor, the electron affinity can be systematically improved by application of higher levels of theory. We also show that employing the reciprocal of ELUMO, which is more consistent with frontier molecular orbital (FMO) theory, improves the correlations with in vitro toxicity data. We offer explanations based on FMO theory for a result from our previous work, in which the LUMO energies of HA anions correlated surprisingly well with in vitro toxicity data. Additional descriptors are also suggested and interpreted in terms of the accepted biophysical mechanism of toxic response to HAs and new QSARs are derived for various chemical categories that compose the data set employed. These alternate descriptors provide important insight and could benefit other classes of compounds where the biophysical mechanism of toxic response involves dissociative attachment.

  9. The Role of Halogens in High-Grade Metamorphism and Anatexis

    NASA Astrophysics Data System (ADS)

    Aranovich, L.; Safonov, O.

    2016-12-01

    We review factors controlling the distribution of the two major halogens, F and Cl, in high-grade metamorphic rocks; their compositional correlations and partitioning between minerals; experimental data on stability and phase equilibria of the halogen-bearing minerals; the influence of halogens on Fe-Mg exchange reactions; and the means of estimating concentrations/activity of halogen species concentration/ activity in the fluid phase ("chlorimetry and fluorimetry") via calculation of equilibrium conditions for mineral assemblages containing halogen-bearing phases. Clear negative correlation between the F content and XFe=Fe/(Fe+Mg) suggests that natural biotite and amphibole obey the Fe-F avoidance rule. A strong positive correlation exists between K and Cl in amphibole. A scattering of points on the XFe -Cl and TiO2- Cl diagrams indicate the possible involvement of an exotic Cl-rich phase (fluid or melt) during the formation of Cl-bearing biotite and amphibole. Fluorine and Cl substituting for OH-groups substantially stabilize minerals relative to dehydration and melting. They should also strongly affect partitioning of Fe and Mg between biotite, amphibole and anhydrous minerals. This effect is quantified for Fe-Mg exchange reactions involving biotite (Zhu and Sverjensky, 1992), but remains to be evaluated for amphibole. Calculations based on recent thermodynamic systematics show that the relatively Mg-rich, Cl-poor biotite (for example, XFe = 0.4 and about 0.2 wt.% Cl) may coexist with a fairly Cl-rich fluid, i.e. total Cl/(Cl+H2O) from 0.1-0.3, depending on the assemblage, under granulite facies P-T conditions. Alkali (and Ca) metasomatism caused by interaction of high grade rocks with halogen-bearing fluids has major impact on the subsolidus phase transformations and melting processes during high-grade metamorphism and anatexis. For example, an increase in sodium content in plagioclase (Pl) by 20 mol% due to infiltration of Na- fluid into the quartz (Qtz

  10. Inorganic Halogen Oxidizer Research

    DTIC Science & Technology

    1975-02-26

    K. 0. Christe and C. J. Schack, Advances Inorg. Chem. Radiochem. 15. "The NF * Radical Cation. Esr Studies of Radiation Effects in NF„+ Salts...and 25°) in a wide variety of polar and nonpolar solvents, such as aqueous solutions, alcohols, ketones , esters, ethers , and aromatic and halogenated... Studies of Radiation Effects in NF, Salts = 4 S. P. Mishra, M. C R. Symons, K. 0. Christe, R. D. Wilson and R. I. Wagner Received. . . August .9

  11. Chemical Evolution of Presolar Organics in Astromaterials

    NASA Technical Reports Server (NTRS)

    Nakamura-Messenger, K.; Clemett, S. J.; Messenger, Scott; Keller, L. P.

    2010-01-01

    Sub-micron, hollow organic globules reported from several carbonaceous chondrites, interplanetary dust particles, and comet Wild-2 samples returned by NASA?s Stardust mission are enriched in N-15/N-14 and D/H compared with terrestrial materials and the parent materials [1-4]. These anomalies are ascribed to the preservation of presolar cold molecular cloud material from where H, C, and N isotopic constraints point to chemical fractionation near 10 K [5]. An origin well beyond the planet forming region and their survival in meteorites suggests submicrometer organic globules were once prevalent throughout the solar nebula. The survival of the membrane structures indicates primitive meteorites and cometary dust particles would have delivered these organic precursors to the early Earth as well as other planets and satellites. The physical, chemical, and isotopic properties of the organic globules varies to its meteorite types and its lithologies. For example, organic globules in the Tagish Lake meteorite are always embedded in fined grained (poorly crystallized) saponite, and hardly encapsulated in coarse grained serpentine, even though saponite and serpentine are both main components of phyllosilicate matrix of the Tagish Lake meteorite. The organic globules are commonly observed in the carbonate-poor lithology but not in the carbonate-rich one. In Tagish Lake, isolated single globules are common, but in the Bells (CM2) meteorite, globules are mostly aggregated. We will review the evolutions of the organic globules from its birth to alteration in the parent bodies in terms of its own physical and chemical properties as well as its associated minerals.

  12. Regional distribution of halogenated organophosphate flame retardants in seawater samples from three coastal cities in China.

    PubMed

    Hu, Mengyang; Li, Jun; Zhang, Beibei; Cui, Qinglan; Wei, Si; Yu, Hongxia

    2014-09-15

    Thirteen samples of seawater were collected from Yellow Sea and East China Sea near Qingdao, Lianyungang, and Xiamen, China. They were analyzed for halogenated organophosphorus flame retardants (OPFRs). The compounds selected for detection were Tris(2-chloroethyl) phosphate (TCEP), Tris(2-chloroisopropyl) phosphate (TCPP), Tris (1,3-dichloro-2-propyl) phosphate (TDCPP), and Tris(2,3-dibromopropyl) phosphate (TDBPP). The total concentrations ranged from 91.87 to 1392 ng/L and the mean concentrations of these four chemicals were 134.44, 84.12, 109.28, and 96.70 ng/L, respectively. TCEP exhibited the highest concentrations, although concentrations of TCPP and TDCPP were also fairly high in Lianyungang and Xiamen. Generally, Lianyungang was the most heavily polluted district, with very high concentrations of TCEP at LYG-2 (550.54 ng/L) and LYG-4 (617.92 ng/L). The main sources of halogenated OPFRs were municipal and industrial effluents of wastewater treatment plants in the nearby economic and industrial zones. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Systematic trends in photonic reagent induced reactions in a homologous chemical family.

    PubMed

    Tibbetts, Katharine Moore; Xing, Xi; Rabitz, Herschel

    2013-08-29

    The growing use of ultrafast laser pulses to induce chemical reactions prompts consideration of these pulses as "photonic reagents" in analogy to chemical reagents. This work explores the prospect that photonic reagents may affect systematic trends in dissociative ionization reactions of a homologous family of halomethanes, much as systematic outcomes are often observed for reactions between homologous families of chemical reagents and chemical substrates. The experiments in this work with photonic reagents of varying pulse energy and linear spectral chirp reveal systematic correlations between observable ion yields and the following set of natural variables describing the substrate molecules: the ionization energy of the parent molecule, the appearance energy of each fragment ion, and the relative strength of carbon-halogen bonds in molecules containing two different halogens. The results suggest that reactions induced by photonic reagents exhibit systematic behavior analogous to that observed in reactions driven by chemical reagents, which provides a basis to consider empirical "rules" for predicting the outcomes of photonic reagent induced reactions.

  14. Color Coding Organic Chemicals for Inventory Control.

    ERIC Educational Resources Information Center

    Wystrach, V. P.; George, Babu

    1985-01-01

    Describes a system in which organic chemicals are recoded for inventory control and reshelving purposes. The system works well in undergraduate organic chemistry or biology laboratories but can be expanded to handle a larger and more complicated inventory. (JN)

  15. Synthesis of observations of halogen-containing gases, ozone, and gaseous elemental mercury in the tropospheric plume of Redoubt Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Kelly, P. J.; Kern, C.; Lopez, T. M.; Werner, C. A.; Roberts, T. J.; Aiuppa, A.; Wang, B.

    2011-12-01

    Volcanoes are strong natural sources of halogen-containing acid gases and mercury. Most halogens are emitted from volcanoes as relatively non-reactive hydrogen halide gases, but recent field and modeling studies have shown that these species can be rapidly transformed into reactive forms via heterogeneous in-plume reactions. In order to further examine the chemical reactions that occur in volcanic plumes and their atmospheric impacts, we made ground and aircraft-based measurements of the composition of the tropospheric plume emitted from Redoubt Volcano, Alaska, which injected over 1 Tg of SO2, plus other gases and aerosols, into the subarctic free troposphere during 2009 and 2010. To our knowledge, our data include the first detailed study of ozone in a volcanic plume as well as the first measurements of HBr, HI, gaseous elemental mercury (GEM), and BrO in the plume of an Alaskan volcano. The composition of the plume was measured on June 20, 2010 using base-treated filter packs at the crater rim and by an instrumented fixed-wing aircraft on June 21 and August 19, 2010. The aircraft was used to track the chemical evolution of the plume up to ~30 km downwind (2 hours plume travel time) from the volcano. The airborne data from June 21 reveals rapid chemical ozone destruction in the plume as well as the strong influence chemical heterogeneity in background air had on plume composition. Airborne measurements on August 19 revealed several ppbv of ozone depletion near the center of the plume at a location ~5 km (20 minutes plume travel time) downwind and spectroscopic retrievals from traverses made under the plume show that BrO was present at a similar location. Simulations with the PlumeChem model reproduce the main features of the observed ozone deficits and evolution with time. The field measurements and model results suggest that autocatalytic release of reactive bromine and the formation of BrO can explain ozone destruction in the plume. Thus, volcanic eruptions in

  16. Halogen free benzoxazine based curable compositions for high T.sub.g applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tietze, Roger; Nguyen, Yen-Loan

    A method for forming a halogen-free curable composition containing a benzoxazine monomer, at least one epoxy resin, a catalyst, a toughening agent and a solvent. The halogen-free curable composition is especially suited for use in automobile and aerospace applications since the composition, upon curing, produces a composite having a high glass transition temperature.

  17. α-Halogenated oxaphosphinanes: Synthesis, unexpected reactions and evaluation as inhibitors of cancer cell proliferation.

    PubMed

    Babouri, Rachida; Rolland, Marc; Sainte-Catherine, Odile; Kabouche, Zahia; Lecouvey, Marc; Bakalara, Norbert; Volle, Jean-Noël; Virieux, David; Pirat, Jean-Luc

    2015-11-02

    This paper describes the preparation and the biological evaluation of α-halogenated oxaphosphinanes. These halogen derivatives were synthetized from a short and stereoselective synthetic sequence starting by previously described hydroxy-precursors 1 and 2 with respectively a glucose and mannose-like configuration. The in vitro biological tests of these unnatural halogenated phosphinosugars, on several cell lines, highlighted, for some of them, their antiproliferative and anti migration and invasion properties at nanomolar concentration. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  18. Symmetric and asymmetric halogen-containing metallocarboranylporphyrins and uses thereof

    DOEpatents

    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.

  19. Occurrence of organic wastewater and other contaminants in cave streams in northeastern Oklahoma and northwestern Arkansas.

    PubMed

    Bidwell, Joseph R; Becker, Carol; Hensley, Steve; Stark, Richard; Meyer, Michael T

    2010-02-01

    The prevalence of organic wastewater compounds in surface waters of the United States has been reported in a number of recent studies. In karstic areas, surface contaminants might be transported to groundwater and, ultimately, cave ecosystems, where they might impact resident biota. In this study, polar organic chemical integrative samplers (POCISs) and semipermeable membrane devices (SPMDs) were deployed in six caves and two surface-water sites located within the Ozark Plateau of northeastern Oklahoma and northwestern Arkansas in order to detect potential chemical contaminants in these systems. All caves sampled were known to contain populations of the threatened Ozark cavefish (Amblyopsis rosae). The surface-water site in Oklahoma was downstream from the outfall of a municipal wastewater treatment plant and a previous study indicated a hydrologic link between this stream and one of the caves. A total of 83 chemicals were detected in the POCIS and SPMD extracts from the surface-water and cave sites. Of these, 55 chemicals were detected in the caves. Regardless of the sampler used, more compounds were detected in the Oklahoma surface-water site than in the Arkansas site or the caves. The organic wastewater chemicals with the greatest mass measured in the sampler extracts included sterols (cholesterol and beta-sitosterol), plasticizers [diethylhexylphthalate and tris(2-butoxyethyl) phosphate], the herbicide bromacil, and the fragrance indole. Sampler extracts from most of the cave sites did not contain many wastewater contaminants, although extracts from samplers in the Oklahoma surface-water site and the cave hydrologically linked to it had similar levels of diethylhexyphthalate and common detections of carbamazapine, sulfamethoxazole, benzophenone, N-diethyl-3-methylbenzamide (DEET), and octophenol monoethoxylate. Further evaluation of this system is warranted due to potential ongoing transport of wastewater-associated chemicals into the cave. Halogenated organics

  20. Occurrence of organic wastewater and other contaminants in cave streams in northeastern Oklahoma and northwestern Arkansas

    USGS Publications Warehouse

    Bidwell, Joseph R.; Becker, C.; Hensley, S.; Stark, R.; Meyer, M.T.

    2010-01-01

    The prevalence of organic wastewater compounds in surface waters of the United States has been reported in a number of recent studies. In karstic areas, surface contaminants might be transported to groundwater and, ultimately, cave ecosystems, where they might impact resident biota. In this study, polar organic chemical integrative samplers (POCISs) and semipermeable membrane devices (SPMDs) were deployed in six caves and two surface-water sites located within the Ozark Plateau of northeastern Oklahoma and northwestern Arkansas in order to detect potential chemical contaminants in these systems. All caves sampled were known to contain populations of the threatened Ozark cavefish (Amblyopsis rosae). The surface-water site in Oklahoma was downstream from the outfall of a municipal wastewater treatment plant and a previous study indicated a hydrologic link between this stream and one of the caves. A total of 83 chemicals were detected in the POCIS and SPMD extracts from the surface-water and cave sites. Of these, 55 chemicals were detected in the caves. Regardless of the sampler used, more compounds were detected in the Oklahoma surface-water site than in the Arkansas site or the caves. The organic wastewater chemicals with the greatest mass measured in the sampler extracts included sterols (cholesterol and ??-sitosterol), plasticizers [diethylhexylphthalate and tris (2-butoxyethyl) phosphate], the herbicide bromacil, and the fragrance indole. Sampler extracts from most of the cave sites did not contain many wastewater contaminants, although extracts from samplers in the Oklahoma surfacewater site and the cave hydrologically linked to it had similar levels of diethylhexyphthalate and common detections of carbamazapine, sulfamethoxazole, benzophenone, N-diethyl-3-methylbenzamide (DEET), and octophenol monoethoxylate. Further evaluation of this system is warranted due to potential ongoing transport of wastewaterassociated chemicals into the cave. Halogenated organics

  1. Skin Sensitizing Potency of Halogenated Platinum Salts.

    EPA Science Inventory

    The relationship between occupational exposure to halogenated platinum (Pt) salts and Pt-specific allergic sensitization is well-established. Although human case reports and clinical studies demonstrate that Pt salts are potent skin sensitizers, no studies have been published tha...

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

    PubMed

    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.

  3. Equilibrium sorption and diffusion rate studies with halogenated organic chemical and sandy aquifer material

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ball, W.P.

    1990-01-01

    Concepts for rate limitation of sorptive uptake of hydrophobic organic solutes by aquifer solids are reviewed, emphasizing physical diffusion models and in the context of effects on contaminant transport. Data for the sorption of tetrachloroethene (PCE) and 1,2,4,5-tetrachlorobenzene (TeCB) on Borden sand are presented, showing that equilibrium is attained very slowly, requiring equilibration times on the order of tens of days for PCE and hundreds of days for TeCB. The rate of approach to equilibrium decreased with increasing particle size and sorption distribution coefficient, in accordance with retarded intragranular diffusion models. Pulverization of the samples significantly decreased the required timemore » to equilibrium without changing the sorption capacity of the solids. Batch sorption methodology was refined to allow accurate measurement of long-term distribution coefficients, using purified {sup 14}C-labelled solute spikes and sealed glass ampules. Sorption isotherms for PCE and TeCB were conducted with size fractions of Borden sand over four to five orders of magnitude in aqueous concentration, and were found to be slightly nonlinear (Freundlich exponent = 0.8). A concentrated set of data in the low concentration range (<50 ug/L) revealed that sorption in this range could be equally well described by a linear isotherm. Distribution coefficients of the two solutes with seven size fractions of Borden sand, measured at low concentration and at full equilibrium, were between seven and sixty times the value predicted on the basis of recent correlations with organic carbon content. Rate results for coarse size fractions support a simple pore diffusion model, with pore diffusion coefficients estimated to be approximately 3 {times} 10{sup {minus}8} cm{sup 2}/sec, more than 200{times} lower than the aqueous diffusivities.« less

  4. DESTRUCTION OF HALOGENATED HYDROCARBONS WITH SOLVATED ELECTRONS IN THE PRESENCE OF WATER. (R826180)

    EPA Science Inventory

    Model halogenated aromatic and aliphatic hydrocarbons and halogenated phenols were dehalogenated in seconds by solvated electrons generated from sodium in both anhydrous liquid ammonia and ammonia/water solutions. The minimum sodium required to completely dehalogenate these mo...

  5. Linking precious metal enrichment and halogen cycling in mafic magmatic systems: insights from the Rum layered intrusion, NW Scotland

    NASA Astrophysics Data System (ADS)

    Kelly, A. P.; O'Driscoll, B.; Clay, P. L.; Burgess, R.

    2017-12-01

    Layered intrusions host the world's largest known concentrations of the platinum-group elements (PGE). Emphasis has been attached to the role of halogen-bearing fluids in concentrating the precious metals, but whether this occurs at the magmatic stage, or via subsequent metasomatism, is actively debated. One obstacle to progress has been the analytical difficulty of measuring low abundances of the halogens in the cumulate products of layered intrusions. To elucidate the importance of the halogens in facilitating PGE-mineralisation, as well as fingerprint halogen provenance and assess the importance of halogen cycling in mafic magma systems more generally, a suite of samples encompassing different stages of activity of the Palaeogene Rum layered intrusion was investigated. Halogen abundances were measured by neutron irradiation noble gas mass spectrometric analysis, permitting the detection of relatively low (ppm-ppb) abundances of Cl, Br and I in mg-sized samples. The samples include PGE-enriched chromite seams, various cumulates (e.g., peridotites), picrites (approximating the Rum parental magma), and pegmatites representing volatile-rich melts that circulated the intrusion at a late-stage in its solidification history. The new data reveal that PGE-bearing chromite seams contain relatively low Cl concentrations (2-3 ppm), with high molar ratios of Br/Cl and I/Cl (0.005 and 0.009, respectively). The picrites and cumulates have Br/Cl and I/Cl ratios close to sub-continental lithospheric mantle values of approximately 0.0013 and 0.00002, respectively, and thus likely reflect the Rum magma source region. A positive correlation between Cl and Br signifies comparable partitioning behaviour in all samples. However, I is more variable, displaying a positive correlation with Cl for more primitive samples (e.g. picrite and peridotite), and seemingly decoupling from Br and Cl in chromite seams and pegmatites. The relative enrichment of I over Cl in the chromite seams points

  6. Removal of trace organic chemical contaminants by a membrane bioreactor.

    PubMed

    Trinh, T; van den Akker, B; Stuetz, R M; Coleman, H M; Le-Clech, P; Khan, S J

    2012-01-01

    Emerging wastewater treatment processes such as membrane bioreactors (MBRs) have attracted a significant amount of interest internationally due to their ability to produce high quality effluent suitable for water recycling. It is therefore important that their efficiency in removing hazardous trace organic contaminants be assessed. Accordingly, this study investigated the removal of trace organic chemical contaminants through a full-scale, package MBR in New South Wales, Australia. This study was unique in the context of MBR research because it characterised the removal of 48 trace organic chemical contaminants, which included steroidal hormones, xenoestrogens, pesticides, caffeine, pharmaceuticals and personal care products (PPCPs). Results showed that the removal of most trace organic chemical contaminants through the MBR was high (above 90%). However, amitriptyline, carbamazepine, diazepam, diclofenac, fluoxetine, gemfibrozil, omeprazole, sulphamethoxazole and trimethoprim were only partially removed through the MBR with the removal efficiencies of 24-68%. These are potential indicators for assessing MBR performance as these chemicals are usually sensitive to changes in the treatment systems. The trace organic chemical contaminants detected in the MBR permeate were 1 to 6 orders of magnitude lower than guideline values reported in the Australian Guidelines for Water Recycling. The outcomes of this study enhanced our understanding of the levels and removal of trace organic contaminants by MBRs.

  7. Halogen Bonding versus Hydrogen Bonding: A Molecular Orbital Perspective

    PubMed Central

    Wolters, Lando P; Bickelhaupt, F Matthias

    2012-01-01

    We have carried out extensive computational analyses of the structure and bonding mechanism in trihalides DX⋅⋅⋅A− and the analogous hydrogen-bonded complexes DH⋅⋅⋅A− (D, X, A=F, Cl, Br, I) using relativistic density functional theory (DFT) at zeroth-order regular approximation ZORA-BP86/TZ2P. One purpose was to obtain a set of consistent data from which reliable trends in structure and stability can be inferred over a large range of systems. The main objective was to achieve a detailed understanding of the nature of halogen bonds, how they resemble, and also how they differ from, the better understood hydrogen bonds. Thus, we present an accurate physical model of the halogen bond based on quantitative Kohn–Sham molecular orbital (MO) theory, energy decomposition analyses (EDA) and Voronoi deformation density (VDD) analyses of the charge distribution. It appears that the halogen bond in DX⋅⋅⋅A− arises not only from classical electrostatic attraction but also receives substantial stabilization from HOMO–LUMO interactions between the lone pair of A− and the σ* orbital of D–X. PMID:24551497

  8. INFLUENCE OF ORGANIC COSOLVENTS ON THE SORPTION KINETICS OF HYDROPHOBIC ORGANIC CHEMICALS

    EPA Science Inventory

    A quantitative examination of the kinetics of sorption of hydrophobic organic chemicals by soils from mixed solvents reveals that the reverse sorption rate constant (k2) increases log-linearly with increasing volume fraction of organic cosolvent (fc). This relationship was expec...

  9. ORGANIC COSOLVENT EFFECTS ON THE SORPTION AND TRANSPORT OF NEUTRAL ORGANIC CHEMICALS

    EPA Science Inventory

    Soil column miscible displacement techniques were used to investigate the effects of an organic cosolvent (methanol) on the sorption and transport of three neutral organic chemicals; naphthalene, phenanthrene, and the herbicide diuron, through a sandy surface soil. A two-domain, ...

  10. Microwave assisted pyrolysis of halogenated plastics recovered from waste computers.

    PubMed

    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.

  11. Synthetic Organic Chemicals: United States Production and Sales, 1976.

    ERIC Educational Resources Information Center

    Adams, Roger; And Others

    This is the sixth annual report of the U.S. Trade Commission on domestic production and sales of synthetic organic chemicals and the raw materials from which they are made. The report consists of 15 sections, each covering a specified group (based primarily on use) of organic chemicals as follows: tar and tar crudes; primary products from…

  12. Halogenated organic contaminants (HOCs) in sediment from a highly eutrophicated lake, China: occurrence, distribution and mass inventories.

    PubMed

    Wang, Ji-Zhong; Liu, Liang-Ying; Zhang, Kai; Liang, Bo; Li, Guo-Lian; Chen, Tian-Hu

    2012-11-01

    Halogenated organic contaminants (HOCs) including 16 polybrominated diphenyl ethers (PBDEs) and 37 polychlorinated biphenyls (PCBs) were determined in 49 surfacial sediments from Chaohu Lake, a highly eutrophicated lake, China. PBDEs were detected in almost samples with the range of the total concentration (defined as Σ(16)PBDEs) from 0.84 to 86.6 ng g(-1). Compared with the occurrence of PBDEs in Pearl River Delta and Yangtze River Delta in China, lower percentage of BDE-209 over the concentration of Σ(16)PBDEs was inferred by the high-volume application of penta-BDE mixture product for local domestic furniture purpose. The total concentration of 37 PCBs (Σ(37)PCBs) ranged from 0.05 to 3.36 ng g(-1) with the most detection of PCB-1, -4, -52 and -71. Both the concentrations of Σ(16)PBDE and Σ(37)PCB poorly correlated with total organic carbon (TOC), suggesting the significant contribution of phytoplankton organic carbons to sediment TOC. The contamination by PBDEs and PCBs in western region of the lake was significantly more serious than in eastern lake. Our findings about the higher residues of PBDEs and PCBs in sediments at the estuary of Nanfei River compared to the other estuaries also supported the conclusion that urban area (Hefei city) was the main source of PBDEs and PCBs. The comparison with the concentration of HOC in the present study with those in other lacustrine sediments around the world suggested the contamination by PBDEs in Chaohu Lake is at middle of the global concentration range, whereas PCBs is at low end of the global range which could be elucidated by local economic development and historical usage of PBDEs and PCBs. The mass inventories of HOCs in the lake were estimated at 561 and 38 kg, which corresponds to only 0.000006% and 0.0001% of these global historical produce volumes, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Groundwater and organic chemicals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dawson, H.E.

    1995-12-01

    Groundwater is a major source of drinking water for many communities. Unfortunately, organic chemicals such as dry cleaning fluids, solvent, fuels, and pesticides have contaminated groundwater in many areas, rendering the groundwater useless as a drinking water resource. In many cases, the groundwater cannot be cleaned up with current technologies, particularly if the groundwater has been contaminated with immiscible (low solubility) organic liquids. In this talk, I will describe the path I have followed from geologist to geochemist and finally to environmental engineer. As a geologist, I studied the chemistry of rock metamorphosis. As a geochemist, I explored for goldmore » and other metals. Now as an environmental engineer, I investigate the behavior of organic liquids in the subsurface. While these fields all appear very different, in reality I have always focused on the interaction of rocks or sediments with the fluids with which they come in contact.« less

  14. Energetics of halogen impurities in thorium dioxide

    NASA Astrophysics Data System (ADS)

    Kuganathan, Navaratnarajah; Ghosh, Partha S.; Arya, Ashok K.; Dey, Gautam K.; Grimes, Robin W.

    2017-11-01

    Defect energies for halogen impurity atoms (Cl, Br and I) in thoria are calculated using the generalized gradient approximation and projector augmented plane wave potentials under the framework of density functional theory. The energy to place a halogen atom at a pre-existing lattice site is the incorporation energy. Seven sites are considered: octahedral interstitial, O vacancy, Th vacancy, Th-O di-vacancy cluster (DV) and the three O-Th-O tri-vacancy cluster (NTV) configurations. For point defects and vacancy clusters, neutral and all possible defect charge states up to full formal charge are considered. The most favourable incorporation site for Cl is the singly charged positive oxygen vacancy while for Br and I it is the NTV1 cluster. By considering the energy to form the defect sites, solution energies are generated. These show that in both ThO2-x and ThO2 the most favourable solution equilibrium site for halides is the single positively charged oxygen vacancy (although in ThO2, I demonstrates the same solubility in the NTV1 and DV clusters). Solution energies are much lower in ThO2-x than in ThO2 indicating that stoichiometry is a significant factor in determining solubility. In ThO2, all three halogens are highly insoluble and in ThO2-x Br and I remain insoluble. Although ½Cl2 is soluble in ThO2-x alternative phases such as ZrCl4 exist which are of lower energy.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chandra, Sankhabrata; Bhattacharya, Atanu, E-mail: atanub@ipc.iisc.ernet.in; Periyasamy, Ganga

    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 ismore » 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.« less

  16. LOSS OF ORGANIC CHEMICALS IN SOIL: PURE COMPOUND TREATABILITY STUDIES

    EPA Science Inventory

    Comprehensive screening data on the treatability of 32 organic chemicals in soil were developed. Of the evaluated chemicals, 22 were phenolic compounds. Aerobic batch laboratory microcosm experiments were conducted using two soils: an acidic clay soil with <1% organic matter and ...

  17. Reconciliation of Halogen-Induced Ozone Loss with the Total-Column Ozone Record

    NASA Technical Reports Server (NTRS)

    Shepherd, T. G.; Plummer, D. A.; Scinocca, J. F.; Hegglin, M. I.; Fioletov, V. E.; Reader, M. C.; Remsberg, E.; von Clarmann, T.; Wang, H. J.

    2014-01-01

    The observed depletion of the ozone layer from the 1980s onwards is attributed to halogen source gases emitted by human activities. However, the precision of this attribution is complicated by year-to-year variations in meteorology, that is, dynamical variability, and by changes in tropospheric ozone concentrations. As such, key aspects of the total-column ozone record, which combines changes in both tropospheric and stratospheric ozone, remain unexplained, such as the apparent absence of a decline in total-column ozone levels before 1980, and of any long-term decline in total-column ozone levels in the tropics. Here we use a chemistry-climate model to estimate changes in halogen-induced ozone loss between 1960 and 2010; the model is constrained by observed meteorology to remove the eects of dynamical variability, and driven by emissions of tropospheric ozone precursors to separate out changes in tropospheric ozone. We show that halogen-induced ozone loss closely followed stratospheric halogen loading over the studied period. Pronounced enhancements in ozone loss were apparent in both hemispheres following the volcanic eruptions of El Chichon and, in particular, Mount Pinatubo, which significantly enhanced stratospheric aerosol loads. We further show that approximately 40% of the long-term non-volcanic ozone loss occurred before 1980, and that long-term ozone loss also occurred in the tropical stratosphere. Finally, we show that halogeninduced ozone loss has declined by over 10% since stratospheric halogen loading peaked in the late 1990s, indicating that the recovery of the ozone layer is well underway.

  18. Scientific Studies in Association with the Halogen Occultation Experiment

    NASA Technical Reports Server (NTRS)

    Mickley, Lorretta J.; Frederick, John E.

    1996-01-01

    This work examines measurements of ozone, NO, NO2, and HCl made by the Halogen Occultation Experiment (HALOE) to track chemical change in the stratosphere. In addition, HALOE observations of two long-lived species, HF and CH4, are used as tracers to distinguish between change due to transport processes and change due to chemistry. The first study investigates the response of NO(x), (NO and NO2) and ozone to the presence of large amounts of sulfate aerosol in the stratosphere following the 1991 eruption of Mount Pinatubo. As the Pinatubo aerosol cleared the atmosphere at 17 mb (about 27-28 km), the partitioning of total reactive nitrogen shifted more toward NO(x), and ozone amounts declined. This trend is opposite that observed at lower altitudes. The second study examines the chemical aftermath of severe ozone depletion over Antarctica in spring. When ozone levels drop to a threshold amount (about 1 ppm near 20 km), the partitioning of the total chlorine family shifts rapidly from reactive species to the reservoir molecule HCl. This sudden repartitioning shuts down further ozone loss and may be significant as filaments of air peel off the polar vortex and mix with mid-latitude air.

  19. Synthesis and characterization of lead-free tin silver nanosolders and their application to halogen free nanosolder pastes

    NASA Astrophysics Data System (ADS)

    Wernicki, Evan

    Solder paste is a key material used in attaching electronic components to printed circuit boards (PCBs). Commonly used lead-based solders, such as eutectic Sn/37Pb, are currently being replaced by lead-free alloy materials due to health and environmental concerns associated with lead. Many solder pastes, both lead-containing and lead-free, contain halogens which act as activators to remove surface oxide and enhance surface wetting, posing further environmental concern from the halogen species. Difficulties in obtaining reliable joints can occur since lead-free solder material candidates have higher melting temperatures (30-50 °C) than that of lead-based solders. Differences in material properties between the numerous materials used in assembly and packaging processes can lead to component damage during manufacturing. Furthermore, designs that include more electrical interconnects in smaller areas give rise for the need for new materials to allow this trend to continue. A surfactant-assisted chemical reduction method was used to synthesize Sn/Ag alloy nanoparticles with a target composition range of 3.5-5 wt% Ag that served as the lead-free solder material within a nanosolder paste. Structure and size characterization via SEM and TEM showed Sn-Ag nanosolders size average approximately 19 nm. Differential scanning calorimetry (DSC) measurements of the nanosolder samples containing 4.5 wt% Ag showed an endothermic peak at 222.5 °C and an onset of 219.2 °C, indicating up to 17.5 °C melting temperature depression when compared to the bulk liquidus value of 240 °C. Composition of the nanosolder material was confirmed using energy dispersive x-ray spectroscopy (EDS) and structures formed were analyzed via x-ray diffraction (XRD). Both halogen-free and halogen-containing flux materials were combined with the nanosolder material, respectively, with varying preparation parameters to form a design of experiments (DoE) for nanosolder paste preparation. Solder pastes

  20. Mouse Model of Halogenated Platinum Salt Hypersensitivity

    EPA Science Inventory

    Occupational exposure to halogenated platinum salts can trigger the development of asthma. Concern for increased asthma risk exists for the general population due to the use of platinum (Pt) in catalytic converters and its emerging use as a diesel fuel additive. To investigate a...

  1. Technology for radiation efficiency measurement of high-power halogen tungsten lamp used in calibration of high-energy laser energy meter.

    PubMed

    Wei, Ji Feng; Hu, Xiao Yang; Sun, Li Qun; Zhang, Kai; Chang, Yan

    2015-03-20

    The calibration method using a high-power halogen tungsten lamp as a calibration source has many advantages such as strong equivalence and high power, so it is very fit for the calibration of high-energy laser energy meters. However, high-power halogen tungsten lamps after power-off still reserve much residual energy and continually radiate energy, which is difficult to be measured. Two measuring systems were found to solve the problems. One system is composed of an integrating sphere and two optical spectrometers, which can accurately characterize the radiative spectra and power-time variation of the halogen tungsten lamp. This measuring system was then calibrated using a normal halogen tungsten lamp made of the same material as the high-power halogen tungsten lamp. In this way, the radiation efficiency of the halogen tungsten lamp after power-off can be quantitatively measured. In the other measuring system, a wide-spectrum power meter was installed far away from the halogen tungsten lamp; thus, the lamp can be regarded as a point light source. The radiation efficiency of residual energy from the halogen tungsten lamp was computed on the basis of geometrical relations. The results show that the halogen tungsten lamp's radiation efficiency was improved with power-on time but did not change under constant power-on time/energy. All the tested halogen tungsten lamps reached 89.3% of radiation efficiency at 50 s after power-on. After power-off, the residual energy in the halogen tungsten lamp gradually dropped to less than 10% of the initial radiation power, and the radiation efficiency changed with time. The final total radiation energy was decided by the halogen tungsten lamp's radiation efficiency, the radiation efficiency of residual energy, and the total power consumption. The measuring uncertainty of total radiation energy was 2.4% (here, the confidence factor is two).

  2. Inorganic Halogen Oxidizer Research

    DTIC Science & Technology

    1981-04-21

    International Rocketdyne Division 6633 Canoga Avenue Canoga Park, California 91304 RI/R.D8l1-14O A ’N-NUAL REPORT INORGANIC HALOGEN OXIDIZER RESEARCH (I...March 1980 through 8 February 198L) 21 April 1981 "Contract N00014-79-C-0176 . GO. 95067 . , Office of Naval Research I-- Power Branch , ,, Code 473...Office of Naval Research Power Branch 11 I-ar Ccovie 473 ~ UMBER OF PA’E1 Arlington. VA 22217 . 76" 74 AONIYONING AGENCY NAME III Dw~S~ d, I f,. .f

  3. Wavelength-tunable waveguides based on polycrystalline organic-inorganic perovskite microwires

    NASA Astrophysics Data System (ADS)

    Wang, Ziyu; Liu, Jingying; Xu, Zai-Quan; Xue, Yunzhou; Jiang, Liangcong; Song, Jingchao; Huang, Fuzhi; Wang, Yusheng; Zhong, Yu Lin; Zhang, Yupeng; Cheng, Yi-Bing; Bao, Qiaoliang

    2016-03-01

    Hybrid organic-inorganic perovskites have emerged as new photovoltaic materials with impressively high power conversion efficiency due to their high optical absorption coefficient and long charge carrier diffusion length. In addition to high photoluminescence quantum efficiency and chemical tunability, hybrid organic-inorganic perovskites also show intriguing potential for diverse photonic applications. In this work, we demonstrate that polycrystalline organic-inorganic perovskite microwires can function as active optical waveguides with small propagation loss. The successful production of high quality perovskite microwires with different halogen elements enables the guiding of light with different colours. Furthermore, it is interesting to find that out-coupled light intensity from the microwire can be effectively modulated by an external electric field, which behaves as an electro-optical modulator. This finding suggests the promising applications of perovskite microwires as effective building blocks in micro/nano scale photonic circuits.

  4. Wavelength-tunable waveguides based on polycrystalline organic-inorganic perovskite microwires.

    PubMed

    Wang, Ziyu; Liu, Jingying; Xu, Zai-Quan; Xue, Yunzhou; Jiang, Liangcong; Song, Jingchao; Huang, Fuzhi; Wang, Yusheng; Zhong, Yu Lin; Zhang, Yupeng; Cheng, Yi-Bing; Bao, Qiaoliang

    2016-03-28

    Hybrid organic-inorganic perovskites have emerged as new photovoltaic materials with impressively high power conversion efficiency due to their high optical absorption coefficient and long charge carrier diffusion length. In addition to high photoluminescence quantum efficiency and chemical tunability, hybrid organic-inorganic perovskites also show intriguing potential for diverse photonic applications. In this work, we demonstrate that polycrystalline organic-inorganic perovskite microwires can function as active optical waveguides with small propagation loss. The successful production of high quality perovskite microwires with different halogen elements enables the guiding of light with different colours. Furthermore, it is interesting to find that out-coupled light intensity from the microwire can be effectively modulated by an external electric field, which behaves as an electro-optical modulator. This finding suggests the promising applications of perovskite microwires as effective building blocks in micro/nano scale photonic circuits.

  5. Auger analysis of films formed on metals in sliding contact with halogenated polymers

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1974-01-01

    The use of Auger electron spectroscopy (AES) to search for transferred polymer must contend with the fact that there has been no published work on Auger analysis of polymers. Since this is a new area for AES, the Auger spectra of polymers and of halogenated polymers in particular is discussed. It is shown that the Auger spectra of halogenated polymers have certain characteristics that permit an assessment of whether a polymeric transfer film has been established by sliding contact. The discussion is general and the concepts should be useful in considering the Auger analysis of any polymer. The polymers chosen for this study are the halogenated polymers polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), and polychlorotrifluorethylene (PCTFE).

  6. Evidence for halogen bond covalency in acyclic and interlocked halogen-bonding receptor anion recognition

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Robinson, Sean W.; Mustoe, Chantal L.; White, Nicholas G.

    The synthesis and anion binding properties of novel halogen-bonding (XB) bis-iodotriazole-pyridinium-containing acyclic and [2]catenane anion host systems are described. The XB acyclic receptor displays selectivity for acetate over halides with enhanced anion recognition properties compared to the analogous hydrogen-bonding (HB) acyclic receptor. A reversal in halide selectivity is observed in the XB [2]catenane, in comparison to the acyclic XB receptor, due to the interlocked host’s unique three-dimensional binding cavity, and no binding is observed for oxoanions. Notable halide anion association constant values determined for the [2]catenane in competitive organic–aqueous solvent mixtures demonstrate considerable enhancement of anion recognition as compared tomore » the HB catenane analogue. X-ray crystallographic analysis of a series of halide catenane complexes reveal strong XB interactions in the solid state. These interactions were studied using Cl and Br K-edge X-ray Absorption Spectroscopy (XAS) indicating intense pre-edge features characteristic of charge transfer from the halide to its bonding partner (σ AX←X–* ← X1s), and providing a direct measure of the degree of covalency in the halogen bond(s). Lastly, the data reveal that the degree of covalency is similar to that which is observed in transition metal coordinate covalent bonds. These results are supported by DFT results, which correlate well with the experimental data.« less

  7. Evidence for halogen bond covalency in acyclic and interlocked halogen-bonding receptor anion recognition

    DOE PAGES

    Robinson, Sean W.; Mustoe, Chantal L.; White, Nicholas G.; ...

    2014-12-05

    The synthesis and anion binding properties of novel halogen-bonding (XB) bis-iodotriazole-pyridinium-containing acyclic and [2]catenane anion host systems are described. The XB acyclic receptor displays selectivity for acetate over halides with enhanced anion recognition properties compared to the analogous hydrogen-bonding (HB) acyclic receptor. A reversal in halide selectivity is observed in the XB [2]catenane, in comparison to the acyclic XB receptor, due to the interlocked host’s unique three-dimensional binding cavity, and no binding is observed for oxoanions. Notable halide anion association constant values determined for the [2]catenane in competitive organic–aqueous solvent mixtures demonstrate considerable enhancement of anion recognition as compared tomore » the HB catenane analogue. X-ray crystallographic analysis of a series of halide catenane complexes reveal strong XB interactions in the solid state. These interactions were studied using Cl and Br K-edge X-ray Absorption Spectroscopy (XAS) indicating intense pre-edge features characteristic of charge transfer from the halide to its bonding partner (σ AX←X–* ← X1s), and providing a direct measure of the degree of covalency in the halogen bond(s). Lastly, the data reveal that the degree of covalency is similar to that which is observed in transition metal coordinate covalent bonds. These results are supported by DFT results, which correlate well with the experimental data.« less

  8. Multinuclear Solid-State Magnetic Resonance as a Sensitive Probe of Structural Changes upon the Occurrence of Halogen Bonding in Co-crystals.

    PubMed

    Widdifield, Cory M; Cavallo, Gabriella; Facey, Glenn A; Pilati, Tullio; Lin, Jingxiang; Metrangolo, Pierangelo; Resnati, Giuseppe; Bryce, David L

    2013-09-02

    Although the understanding of intermolecular interactions, such as hydrogen bonding, is relatively well-developed, many additional weak interactions work both in tandem and competitively to stabilize a given crystal structure. Due to a wide array of potential applications, a substantial effort has been invested in understanding the halogen bond. Here, we explore the utility of multinuclear ((13)C, (14/15)N, (19)F, and (127)I) solid-state magnetic resonance experiments in characterizing the electronic and structural changes which take place upon the formation of five halogen-bonded co-crystalline product materials. Single-crystal X-ray diffraction (XRD) structures of three novel co-crystals which exhibit a 1:1 stoichiometry between decamethonium diiodide (i.e., [(CH3)3N(+)(CH2)10N(+)(CH3)3][2 I(-)]) and different para-dihalogen-substituted benzene moieties (i.e., p-C6X2Y4, X=Br, I; Y=H, F) are presented. (13)C and (15)N NMR experiments carried out on these and related systems validate sample purity, but also serve as indirect probes of the formation of a halogen bond in the co-crystal complexes in the solid state. Long-range changes in the electronic environment, which manifest through changes in the electric field gradient (EFG) tensor, are quantitatively measured using (14)N NMR spectroscopy, with a systematic decrease in the (14)N quadrupolar coupling constant (CQ) observed upon halogen bond formation. Attempts at (127)I solid-state NMR spectroscopy experiments are presented and variable-temperature (19)F NMR experiments are used to distinguish between dynamic and static disorder in selected product materials, which could not be conclusively established using solely XRD. Quantum chemical calculations using the gauge-including projector augmented-wave (GIPAW) or relativistic zeroth-order regular approximation (ZORA) density functional theory (DFT) approaches complement the experimental NMR measurements and provide theoretical corroboration for the changes in NMR

  9. Encoding of Fundamental Chemical Entities of Organic Reactivity Interest using chemical ontology and XML.

    PubMed

    Durairaj, Vijayasarathi; Punnaivanam, Sankar

    2015-09-01

    Fundamental chemical entities are identified in the context of organic reactivity and classified as appropriate concept classes namely ElectronEntity, AtomEntity, AtomGroupEntity, FunctionalGroupEntity and MolecularEntity. The entity classes and their subclasses are organized into a chemical ontology named "ChemEnt" for the purpose of assertion, restriction and modification of properties through entity relations. Individual instances of entity classes are defined and encoded as a library of chemical entities in XML. The instances of entity classes are distinguished with a unique notation and identification values in order to map them with the ontology definitions. A model GUI named Entity Table is created to view graphical representations of all the entity instances. The detection of chemical entities in chemical structures is achieved through suitable algorithms. The possibility of asserting properties to the entities at different levels and the mechanism of property flow within the hierarchical entity levels is outlined. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Identification of methyl triclosan and halogenated analogues in male common carp (Cyprinus carpio) from Las Vegas Bay and semipermeable membrane devices from Las Vegas Wash, Nevada

    USGS Publications Warehouse

    Leiker, T.J.; Abney, S.R.; Goodbred, S.L.; Rosen, Michael R.

    2009-01-01

    Methyl triclosan and four halogenated analogues have been identified in extracts of individual whole-body male carp (Cyprinus carpio) tissue that were collected from Las Vegas Bay, Nevada, and Semipermeable Membrane Devices (SPMD) that were deployed in Las Vegas Wash, Nevada. Methyl triclosan is believed to be the microbially methylated product of the antibacterial agent triclosan (2, 4, 4'-trichloro-4-hydroxydiphenyl ether, Chemical Abstract Service Registry Number 3380-34-5, Irgasan DP300). The presence of methyl triclosan and four halogenated analogues was confirmed in SPMD extracts by comparing low- and high-resolution mass spectral data and Kovats retention indices of methyl triclosan with commercially obtained triclosan that was derivatized to the methyl ether with ethereal diazomethane. The four halogenated analogues of methyl triclosan detected in both whole-body tissue and SPMD extracts were tentatively identified by high resolution mass spectrometry. Methyl triclosan was detected in all 29 male common carp from Las Vegas Bay with a mean concentration of 596????g kg- 1 wet weight (ww) which is more than an order of magnitude higher than previously reported concentrations in the literature. The halogenated analogs were detected less frequently (21%-76%) and at much lower concentrations (< 51????g kg- 1 ww). None of these compounds were detected in common carp from a Lake Mead reference site in Overton Arm, Nevada.

  11. 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)

    NASA Astrophysics Data System (ADS)

    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.

  12. Quantum Dot and Polymer Composite Cross-Reactive Array for Chemical Vapor Detection.

    PubMed

    Bright, Collin J; Nallon, Eric C; Polcha, Michael P; Schnee, Vincent P

    2015-12-15

    A cross-reactive chemical sensing array was made from CdSe Quantum Dots (QDs) and five different organic polymers by inkjet printing to create segmented fluorescent composite regions on quartz substrates. The sensor array was challenged with exposures from two sets of analytes, including one set of 14 different functionalized benzenes and one set of 14 compounds related to security concerns, including the explosives trinitrotoluene (TNT) and ammonium nitrate. The array was broadly responsive to analytes with different chemical functionalities due to the multiple sensing mechanisms that altered the QDs' fluorescence. The sensor array displayed excellent discrimination between members within both sets. Classification accuracy of more than 93% was achieved, including the complete discrimination of very similar dinitrobenzene isomers and three halogenated, substituted benzene compounds. The simple fabrication, broad responsivity, and high discrimination capacity of this type of cross-reactive array are ideal qualities for the development of sensors with excellent sensitivity to chemical and explosive threats while maintaining low false alarm rates.

  13. Organic Elemental Analysis.

    ERIC Educational Resources Information Center

    Ma, T. S.; Wang, C. Y.

    1984-01-01

    Presents a literature review on methods used to analyze organic elements. Topic areas include methods for: (1) analyzing carbon, hydrogen, and nitrogen; (2) analyzing oxygen, sulfur, and halogens; (3) analyzing other elements; (4) simultaneously determining several elements; and (5) determing trace elements. (JN)

  14. Uptake, Metabolism, and Tissue Distribution of Chemicals in Organisms

    EPA Science Inventory

    This talk will explain how chemicals get into aquatic species, what tissues and organs the chemicals move into, and what can happen to the chemicals once they get there. This will be presented using examples from recent studies conducted using state-of-the-art microscopy with em...

  15. Combined Diffraction and Density Functional Theory Calculations of Halogen-Bonded Cocrystal Monolayers

    PubMed Central

    2013-01-01

    This work describes the combined use of synchrotron X-ray diffraction and density functional theory (DFT) calculations to understand the cocrystal formation or phase separation in 2D monolayers capable of halogen bonding. The solid monolayer structure of 1,4-diiodobenzene (DIB) has been determined by X-ray synchrotron diffraction. The mixing behavior of DIB with 4,4′-bipyridyl (BPY) has also been studied and interestingly is found to phase-separate rather than form a cocrystal, as observed in the bulk. DFT calculations are used to establish the underlying origin of this interesting behavior. The DFT calculations are demonstrated to agree well with the recently proposed monolayer structure for the cocrystal of BPY and 1,4-diiodotetrafluorobenzene (DITFB) (the perfluorinated analogue of DIB), where halogen bonding has also been identified by diffraction. Here we have calculated an estimate of the halogen bond strength by DFT calculations for the DITFB/BPY cocrystal monolayer, which is found to be ∼20 kJ/mol. Computationally, we find that the nonfluorinated DIB and BPY are not expected to form a halogen-bonded cocrystal in a 2D layer; for this pair of species, phase separation of the components is calculated to be lower energy, in good agreement with the diffraction results. PMID:24215390

  16. Combined diffraction and density functional theory calculations of halogen-bonded cocrystal monolayers.

    PubMed

    Sacchi, Marco; Brewer, Adam Y; Jenkins, Stephen J; Parker, Julia E; Friščić, Tomislav; Clarke, Stuart M

    2013-12-03

    This work describes the combined use of synchrotron X-ray diffraction and density functional theory (DFT) calculations to understand the cocrystal formation or phase separation in 2D monolayers capable of halogen bonding. The solid monolayer structure of 1,4-diiodobenzene (DIB) has been determined by X-ray synchrotron diffraction. The mixing behavior of DIB with 4,4'-bipyridyl (BPY) has also been studied and interestingly is found to phase-separate rather than form a cocrystal, as observed in the bulk. DFT calculations are used to establish the underlying origin of this interesting behavior. The DFT calculations are demonstrated to agree well with the recently proposed monolayer structure for the cocrystal of BPY and 1,4-diiodotetrafluorobenzene (DITFB) (the perfluorinated analogue of DIB), where halogen bonding has also been identified by diffraction. Here we have calculated an estimate of the halogen bond strength by DFT calculations for the DITFB/BPY cocrystal monolayer, which is found to be ∼20 kJ/mol. Computationally, we find that the nonfluorinated DIB and BPY are not expected to form a halogen-bonded cocrystal in a 2D layer; for this pair of species, phase separation of the components is calculated to be lower energy, in good agreement with the diffraction results.

  17. Mechanochemical synthesis of small organic molecules

    PubMed Central

    Achar, Tapas Kumar; Bose, Anima

    2017-01-01

    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. PMID:29062410

  18. 40 CFR 455.20 - Applicability; description of the organic pesticide chemicals manufacturing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... organic pesticide chemicals manufacturing subcategory. 455.20 Section 455.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) PESTICIDE CHEMICALS Organic Pesticide Chemicals Manufacturing Subcategory § 455.20 Applicability; description of the organic...

  19. 40 CFR 455.20 - Applicability; description of the organic pesticide chemicals manufacturing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... organic pesticide chemicals manufacturing subcategory. 455.20 Section 455.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS PESTICIDE CHEMICALS Organic Pesticide Chemicals Manufacturing Subcategory § 455.20 Applicability; description of the organic pesticide...

  20. 40 CFR 455.20 - Applicability; description of the organic pesticide chemicals manufacturing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... organic pesticide chemicals manufacturing subcategory. 455.20 Section 455.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS PESTICIDE CHEMICALS Organic Pesticide Chemicals Manufacturing Subcategory § 455.20 Applicability; description of the organic pesticide...

  1. Desorption kinetics of organic chemicals from albumin.

    PubMed

    Krause, Sophia; Ulrich, Nadin; Goss, Kai-Uwe

    2018-03-01

    When present in blood, most chemicals tend to bind to the plasma protein albumin. For distribution into surrounding tissues, desorption from albumin is necessary, because only the unbound form of a chemical is assumed to be able to cross cell membranes. For metabolism of chemicals, the liver is a particularly important organ. One potentially limiting step for hepatic uptake of the chemicals is desorption from albumin, because blood passes the human liver within seconds. Desorption kinetics from albumin can thus be an important parameter for our pharmacokinetic and toxicokinetic understanding of chemicals. This work presents a dataset of measured desorption rate constants and reveals a possibility for their prediction. Additionally, the obtained extraction profiles directly indicate physiological relevance of desorption kinetics, because desorption of the test chemicals is still incomplete after time frames comparable to the residence time of blood in the liver.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Vacuum-based surface modification of organic and metallic substrates

    NASA Astrophysics Data System (ADS)

    Torres, Jessica

    Surface physico-chemical properties play an important role in the development and performance of materials in different applications. Consequently, understanding the chemical and physical processes involved during surface modification strategies is of great scientific and technological importance. This dissertation presents results from the surface modification of polymers, organic films and metallic substrates with reactive species, with the intent of simulating important modification processes and elucidating surface property changes of materials under different environments. The reactions of thermally evaporated copper and titanium with halogenated polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC) are used to contrast the interaction of metals with polymers. Results indicate that reactive metallization is thermodynamically favored when the metal-halogen bond strength is greater than the carbon-halogen bond strength. X-ray post-metallization treatment results in an increase in metal-halide bond formation due to the production of volatile halogen species in the polymer that react with the metallic overlayer. The reactions of atomic oxygen (AO) and atomic chlorine with polyethylene (PE) and self-assembled monolayers (SAMs) films were followed to ascertain the role of radical species during plasma-induced polymer surface modification. The reactions of AO with X-ray modified SAMs are initially the dominated by the incorporation of new oxygen containing functionality at the vacuum/film interface, leading to the production of volatile carbon containing species such as CO2 that erodes the hydrocarbon film. The reaction of atomic chlorine species with hydrocarbon SAMs, reveals that chlorination introduces C-Cl and C-Cl2 functionalities without erosion. A comparison of the reactions of AO and atomic chlorine with PE reveal a maximum incorporation of the corresponding C-O and C-Cl functionalities at the polymer surface. A novel method to prepare phosphorous

  4. Engaging the Terminal: Promoting Halogen Bonding Interactions with Uranyl Oxo Atoms.

    PubMed

    Carter, Korey P; Kalaj, Mark; Surbella, Robert G; Ducati, Lucas C; Autschbach, Jochen; Cahill, Christopher L

    2017-11-02

    Engaging the nominally terminal oxo atoms of the linear uranyl (UO 2 2+ ) cation in non-covalent interactions represents both a significant challenge and opportunity within the field of actinide hybrid materials. An approach has been developed for promoting oxo atom participation in a range of non-covalent interactions, through judicious choice of electron donating equatorial ligands and appropriately polarizable halogen-donor atoms. As such, a family of uranyl hybrid materials was generated based on a combination of 2,5-dihalobenzoic acid and aromatic, chelating N-donor ligands. Delineation of criteria for oxo participation in halogen bonding interactions has been achieved by preparing materials containing 2,5-dichloro- (25diClBA) and 2,5-dibromobenzoic acid (25diBrBA) coupled with 2,2'-bipyridine (bipy) (1 and 2), 1,10-phenanthroline (phen) (3-5), 2,2':6',2''-terpyridine (terpy) (6-8), or 4'-chloro-2,2':6',2''-terpyridine (Cl-terpy) (9-10), which have been characterized through single crystal X-ray diffraction, Raman, Infrared (IR), and luminescence spectroscopy, as well as through density functional calculations of electrostatic potentials. Looking comprehensively, these results are compared with recently published analogues featuring 2,5-diiodobenzoic acid which indicate that although inclusion of a capping ligand in the uranyl first coordination sphere is important, it is the polarizability of the selected halogen atom that ultimately drives halogen bonding interactions with the uranyl oxo atoms. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. High-performance air-stable n-channel organic thin film transistors based on halogenated perylene bisimide semiconductors.

    PubMed

    Schmidt, Rüdiger; Oh, Joon Hak; Sun, Ya-Sen; Deppisch, Manuela; Krause, Ana-Maria; Radacki, Krzysztof; Braunschweig, Holger; Könemann, Martin; Erk, Peter; Bao, Zhenan; Würthner, Frank

    2009-05-06

    The syntheses and comprehensive characterization of 14 organic semiconductors based on perylene bisimide (PBI) dyes that are equipped with up to four halogen substituents in the bay area of the perylene core and five different highly fluorinated imide substituents are described. The influence of the substituents on the LUMO level and the solid state packing of PBIs was examined by cyclic voltammetry and single crystal structure analyses of seven PBI derivatives, respectively. Top-contact/bottom-gate organic thin film transistor (OTFT) devices were constructed by vacuum deposition of these PBIs on SiO(2) gate dielectrics that had been pretreated with n-octadecyl triethoxysilane in vapor phase (OTS-V) or solution phase (OTS-S). The electrical characterization of all devices was accomplished in a nitrogen atmosphere as well as in air, and the structural features of thin films were explored by grazing incidence X-ray diffraction (GIXD) and atomic force microscopy (AFM). Several of those PBIs that bear only hydrogen or up to two fluorine substitutents at the concomitantly flat PBI core afforded excellent n-channel transistors, in particular, on OTS-S substrate and even in air (mu > 0.5 cm(2) V(-1) s(-1); I(on)/I(off) > 10(6)). The best OTFTs were obtained for 2,2,3,3,4,4,4-heptafluorobutyl-substituted PBI 1a ("PTCDI-C4F7") on OTS-S with n-channel field effect mobilities consistently >1 cm(2) V(-1) s(-1) and on-to-off current rations of 10(6) in a nitrogen atmosphere and in air. For distorted core-tetrahalogenated (fluorine, chlorine, or bromine) PBIs, less advantageous solid state packing properties were found and high performance OTFTs were obtained from only one tetrachlorinated derivative (2d on OTS-S). The excellent on-to-off current modulation combined with high mobility in air makes these PBIs suitable for a wide range of practical applications.

  6. ESTIMATING DISSOLVED ORGANIC CARBON PARTITION COEFFICIENTS FOR NONIONIC ORGANIC CHEMICALS

    EPA Science Inventory

    A literature search was performed for dissolved organic carbon/water partition coefficients for nonionic chemicals (Kdoc) and Kdoc data was taken from more than sixty references. The Kdoc data were evaluated as a function of the n-octanol/water partition coefficients (Kow). A pre...

  7. Carotenoids Database: structures, chemical fingerprints and distribution among organisms.

    PubMed

    Yabuzaki, Junko

    2017-01-01

    To promote understanding of how organisms are related via carotenoids, either evolutionarily or symbiotically, or in food chains through natural histories, we built the Carotenoids Database. This provides chemical information on 1117 natural carotenoids with 683 source organisms. For extracting organisms closely related through the biosynthesis of carotenoids, we offer a new similarity search system 'Search similar carotenoids' using our original chemical fingerprint 'Carotenoid DB Chemical Fingerprints'. These Carotenoid DB Chemical Fingerprints describe the chemical substructure and the modification details based upon International Union of Pure and Applied Chemistry (IUPAC) semi-systematic names of the carotenoids. The fingerprints also allow (i) easier prediction of six biological functions of carotenoids: provitamin A, membrane stabilizers, odorous substances, allelochemicals, antiproliferative activity and reverse MDR activity against cancer cells, (ii) easier classification of carotenoid structures, (iii) partial and exact structure searching and (iv) easier extraction of structural isomers and stereoisomers. We believe this to be the first attempt to establish fingerprints using the IUPAC semi-systematic names. For extracting close profiled organisms, we provide a new tool 'Search similar profiled organisms'. Our current statistics show some insights into natural history: carotenoids seem to have been spread largely by bacteria, as they produce C30, C40, C45 and C50 carotenoids, with the widest range of end groups, and they share a small portion of C40 carotenoids with eukaryotes. Archaea share an even smaller portion with eukaryotes. Eukaryotes then have evolved a considerable variety of C40 carotenoids. Considering carotenoids, eukaryotes seem more closely related to bacteria than to archaea aside from 16S rRNA lineage analysis. : http://carotenoiddb.jp. © The Author(s) 2017. Published by Oxford University Press.

  8. 40 CFR 455.30 - Applicability; description of the metallo-organic pesticide chemicals manufacturing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... metallo-organic pesticide chemicals manufacturing subcategory. 455.30 Section 455.30 Protection of...) PESTICIDE CHEMICALS Metallo-Organic Pesticide Chemicals Manufacturing Subcategory § 455.30 Applicability; description of the metallo-organic pesticide chemicals manufacturing subcategory. The provisions of this...

  9. 40 CFR 455.30 - Applicability; description of the metallo-organic pesticide chemicals manufacturing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... metallo-organic pesticide chemicals manufacturing subcategory. 455.30 Section 455.30 Protection of...) PESTICIDE CHEMICALS Metallo-Organic Pesticide Chemicals Manufacturing Subcategory § 455.30 Applicability; description of the metallo-organic pesticide chemicals manufacturing subcategory. The provisions of this...

  10. 40 CFR 455.30 - Applicability; description of the metallo-organic pesticide chemicals manufacturing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... metallo-organic pesticide chemicals manufacturing subcategory. 455.30 Section 455.30 Protection of...) PESTICIDE CHEMICALS Metallo-Organic Pesticide Chemicals Manufacturing Subcategory § 455.30 Applicability; description of the metallo-organic pesticide chemicals manufacturing subcategory. The provisions of this...

  11. Organic Elemental Analysis.

    ERIC Educational Resources Information Center

    Ma, T. S.; Gutterson, Milton

    1980-01-01

    Reviews general developments in computerization and data processing of organic elemental analyses; carbon, hydrogen, and nitrogen analyzers; procedures for determining oxygen, sulfur, and halogens, as well as other nometallic elements and organometallics. Selected papers on trace analysis of nonmetals and determination of metallic elements are…

  12. Organic Lecture Demonstrations.

    ERIC Educational Resources Information Center

    Silversmith, Ernest F.

    1988-01-01

    Provides a listing of 35 demonstrations designed to generate interest in organic chemistry and help put points across. Topics include opening lecture; molecular structure and properties; halogenation; nucleophilic substitution, alkenes and dienes, stereochemistry, spectroscopy, alcohols and phenols, aldehydes and ketones; carboxylic acids, amines,…

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

    EPA Science Inventory

    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...

  14. Comparing colour discrimination and proofreading performance under compact fluorescent and halogen lamp lighting.

    PubMed

    Mayr, Susanne; Köpper, Maja; Buchner, Axel

    2013-01-01

    Legislation in many countries has banned inefficient household lighting. Consequently, classic incandescent lamps have to be replaced by more efficient alternatives such as halogen and compact fluorescent lamps (CFL). Alternatives differ in their spectral power distributions, implying colour-rendering differences. Participants performed a colour discrimination task - the Farnsworth-Munsell 100 Hue Test--and a proofreading task under CFL or halogen lighting of comparable correlated colour temperatures at low (70 lx) or high (800 lx) illuminance. Illuminance positively affected colour discrimination and proofreading performance, whereas the light source was only relevant for colour discrimination. Discrimination was impaired with CFL lighting. There were no differences between light sources in terms of self-reported physical discomfort and mood state, but the majority of the participants correctly judged halogen lighting to be more appropriate for discriminating colours. The findings hint at the colour-rendering deficiencies associated with energy-efficient CFLs. In order to compare performance under energy-efficient alternatives of classic incandescent lighting, colour discrimination and proofreading performance was compared under CFL and halogen lighting. Colour discrimination was impaired under CFLs, which hints at the practical drawbacks associated with the reduced colour-rendering properties of energy-efficient CFLs.

  15. Extensive halogen-mediated ozone destruction over the tropical Atlantic Ocean.

    PubMed

    Read, Katie A; Mahajan, Anoop S; Carpenter, Lucy J; Evans, Mathew J; Faria, Bruno V E; Heard, Dwayne E; Hopkins, James R; Lee, James D; Moller, Sarah J; Lewis, Alastair C; Mendes, Luis; McQuaid, James B; Oetjen, Hilke; Saiz-Lopez, Alfonso; Pilling, Michael J; Plane, John M C

    2008-06-26

    Increasing tropospheric ozone levels over the past 150 years have led to a significant climate perturbation; the prediction of future trends in tropospheric ozone will require a full understanding of both its precursor emissions and its destruction processes. A large proportion of tropospheric ozone loss occurs in the tropical marine boundary layer and is thought to be driven primarily by high ozone photolysis rates in the presence of high concentrations of water vapour. A further reduction in the tropospheric ozone burden through bromine and iodine emitted from open-ocean marine sources has been postulated by numerical models, but thus far has not been verified by observations. Here we report eight months of spectroscopic measurements at the Cape Verde Observatory indicative of the ubiquitous daytime presence of bromine monoxide and iodine monoxide in the tropical marine boundary layer. A year-round data set of co-located in situ surface trace gas measurements made in conjunction with low-level aircraft observations shows that the mean daily observed ozone loss is approximately 50 per cent greater than that simulated by a global chemistry model using a classical photochemistry scheme that excludes halogen chemistry. We perform box model calculations that indicate that the observed halogen concentrations induce the extra ozone loss required for the models to match observations. Our results show that halogen chemistry has a significant and extensive influence on photochemical ozone loss in the tropical Atlantic Ocean boundary layer. The omission of halogen sources and their chemistry in atmospheric models may lead to significant errors in calculations of global ozone budgets, tropospheric oxidizing capacity and methane oxidation rates, both historically and in the future.

  16. CHEMICAL TRANSPORT FACILITATED BY COLLOIDAL-SIZED ORGANIC MOLECULES

    EPA Science Inventory

    The fluid passing through the pores of soils and geologic materials is not just water with dissolved inorganic chemicals, but a complex mixture of organic and inorganic molecules. Large organic molecules such as humic and fulvic materials may impact the movement of contaminants. ...

  17. Bioanalytical and chemical assessment of the disinfection by-product formation potential: role of organic matter.

    PubMed

    Farré, Maria José; Day, Sophie; Neale, Peta A; Stalter, Daniel; Tang, Janet Y M; Escher, Beate I

    2013-09-15

    Disinfection by-products (DBP) formed from natural organic matter and disinfectants like chlorine and chloramine may cause adverse health effects. Here, we evaluate how the quantity and quality of natural organic matter and other precursors influence the formation of DBPs during chlorination and chloramination using a comprehensive approach including chemical analysis of regulated and emerging DBPs, total organic halogen quantification, organic matter characterisation and bioanalytical tools. In vitro bioassays allow us to assess the hazard potential of DBPs early in the chain of cellular events, when the DBPs react with their molecular target(s) and activate stress response and defence mechanisms. Given the reactive properties of known DBPs, a suite of bioassays targeting reactive modes of toxic action including genotoxicity and sensitive early warning endpoints such as protein damage and oxidative stress were evaluated in addition to cytotoxicity. Coagulated surface water was collected from three different drinking water treatment plants, along with reverse osmosis permeate from a desalination plant, and DBP formation potential was assessed after chlorination and chloramination. While effects were low or below the limit of detection before disinfection, the observed effects and DBP levels increased after disinfection and were generally higher after chlorination than after chloramination, indicating that chlorination forms higher concentrations of DBPs or more potent DBPs in the studied waters. Bacterial cytotoxicity, assessed using the bioluminescence inhibition assay, and induction of the oxidative stress response were the most sensitive endpoints, followed by genotoxicity. Source waters with higher dissolved organic carbon levels induced increased DBP formation and caused greater effects in the endpoints related to DNA damage repair, glutathione conjugation/protein damage and the Nrf2 oxidative stress response pathway after disinfection. Fractionation studies

  18. Unexpected autumnal halogen activity in the lower troposphere at Neumayer III/Antarctica

    NASA Astrophysics Data System (ADS)

    Nasse, Jan-Marcus; Frieß, Udo; Pöhler, Denis; Schmitt, Stefan; Weller, Rolf; Schaefer, Thomas; Platt, Ulrich

    2017-04-01

    The influence of Reactive Halogen Species (RHS, like IO, BrO, ClO, etc.) on the lower polar troposphere has been subject of intense research for several decades. Ozone Depletion Events (ODEs) caused by the catalytic reaction of tropospheric ozone with inorganic halogen species or the oxidation of gaseous elemental mercury are well observed phenomena that occur during the respective springtime in both Arctic and Antarctica. Chlorine atoms also react more efficiently with hydrocarbons than e.g. OH radicals and all reactive halogen species can furthermore influence the atmospheric sulphur or nitrate cycles. While an autocatalytic release mechanism from salty surfaces, the so called bromine explosion, has been identified to rapidly increase inorganic bromine mixing ratios many aspects of atmospheric halogen chemistry in polar regions remains unclear. Since January 2016, we are operating an active Long Path DOAS instrument at Neumayer III on the Antarctic Ekström shelf ice designed for autonomous measurements. This instrument is able to detect a wide range of trace gases absorbing in the UV/Vis including ClO, BrO, OClO, IO, I2, OIO, ozone, NO2, H2O, O4, and SO2 at a temporal resolution of 5-30 minutes. The analysis of the first year of observations shows several surprising findings which give new insights into polar halogen chemistry. E.g. we observe surprisingly strong bromine activity in late summer and autumn (in addition to well-known springtime events) with mixing ratios often higher than 20 pptv. We could even observe peak mixing ratios of 110 pptv. The observed BrO levels could be the result of local/regional chemistry rather than long-range transport and modulated by the stability of the boundary layer. Also, there are hints for NOx - driven halogen activation. Furthermore, chlorine monoxide (ClO) and OClO mixing ratios of several ten pptv could be detected on a number of days, however the source mechanism for reactive chlorine remains unclear. We will give an

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

    PubMed

    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.

  20. Temperature response of litter and soil organic matter decomposition is determined by chemical composition of organic material.

    PubMed

    Erhagen, Björn; Öquist, Mats; Sparrman, Tobias; Haei, Mahsa; Ilstedt, Ulrik; Hedenström, Mattias; Schleucher, Jürgen; Nilsson, Mats B

    2013-12-01

    The global soil carbon pool is approximately three times larger than the contemporary atmospheric pool, therefore even minor changes to its integrity may have major implications for atmospheric CO2 concentrations. While theory predicts that the chemical composition of organic matter should constitute a master control on the temperature response of its decomposition, this relationship has not yet been fully demonstrated. We used laboratory incubations of forest soil organic matter (SOM) and fresh litter material together with NMR spectroscopy to make this connection between organic chemical composition and temperature sensitivity of decomposition. Temperature response of decomposition in both fresh litter and SOM was directly related to the chemical composition of the constituent organic matter, explaining 90% and 70% of the variance in Q10 in litter and SOM, respectively. The Q10 of litter decreased with increasing proportions of aromatic and O-aromatic compounds, and increased with increased contents of alkyl- and O-alkyl carbons. In contrast, in SOM, decomposition was affected only by carbonyl compounds. To reveal why a certain group of organic chemical compounds affected the temperature sensitivity of organic matter decomposition in litter and SOM, a more detailed characterization of the (13) C aromatic region using Heteronuclear Single Quantum Coherence (HSQC) was conducted. The results revealed considerable differences in the aromatic region between litter and SOM. This suggests that the correlation between chemical composition of organic matter and the temperature response of decomposition differed between litter and SOM. The temperature response of soil decomposition processes can thus be described by the chemical composition of its constituent organic matter, this paves the way for improved ecosystem modeling of biosphere feedbacks under a changing climate. © 2013 John Wiley & Sons Ltd.

  1. Rapid and reliable determination of the halogenating peroxidase activity in blood samples.

    PubMed

    Flemmig, Jörg; Schwarz, Pauline; Bäcker, Ingo; Leichsenring, Anna; Lange, Franziska; Arnhold, Jürgen

    2014-12-15

    By combining easy and fast leukocyte enrichment with aminophenyl-fluorescein (APF) staining we developed a method to quickly and specifically address the halogenating activity of the immunological relevant blood heme peroxidases myeloperoxidase and eosinophil peroxidase, respectively. For leukocyte enrichment a two-fold hypotonic lysis procedure of the blood with Millipore water was chosen which represents a cheap, fast and reliable method to diminish the amount of erythrocytes in the samples. This procedure is shown to be suitable both to human and murine blood micro-samples, making it also applicable to small animal experiments with recurring blood sampling. As all types of leukocytes are kept in the sample during the preparation, they can be analysed separately after discrimination during the flow cytometry analysis. This also holds for all heme peroxidase-containing cells, namely neutrophils, eosinophils and monocytes. Moreover additional parameters (e.g. antibody staining) can be combined with the heme peroxidase activity determination to gain additional information about the different immune cell types. Based on previous results we applied APF for specifically addressing the halogenating activity of leukocyte peroxidases in blood samples. This dye is selectively oxidized by the MPO and EPO halogenation products hypochlorous and hypobromous acid. This approach may provide a suitable tool to gain more insights into the immune-physiological role of the halogenating activity of heme peroxidases. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Laws of organization and chemical analysis: Blainville and Müller.

    PubMed

    Duchesneau, François

    2016-12-01

    When "general physiology" emerged as a basic field of research within biology in the early nineteenth century, Henri Ducrotay de Blainville (1777-1850) on the one hand and Johannes Peter Müller (1801-1858) on the other appealed to chemical analysis to account for the properties and operations of organisms that were observed to differ from what was found in inorganic compounds. Their aim was to establish laws of vital organization that would be based on organic chemical processes, but would also be of use to explain morphological and functional differences among life forms. The intent of this paper is to specify for each of these leading physiologists the different presuppositions that provided theoretical frameworks for their interpretation of what they conceived of as laws of organization underpinning the dynamics of vital phenomena. Blainville presumed that the properties of organic compounds depended on the chemical properties of their constitutive molecules, but combined according to patterns of functional development, and that the latter could only be inferred from an empirical survey of modes of organization across the spectrum of life forms. For Müller, while all vital processes involved chemical reactions, in the formative and functional operations of organisms, these reactions would result from the action of life forces that were responsible for the production of organic combinations and thus for vital and animal functions. As both physiologists set significant methodological patterns for their many disciples and followers, their respective quasi-reductionist and anti-reductionist positions need to be accounted for.

  3. Volatile organic compounds in stormwater from a community of Beijing, China.

    PubMed

    Li, Haiyan; Wang, Youshu; Liu, Fei; Tong, Linlin; Li, Kun; Yang, Hua; Zhang, Liang

    2018-08-01

    Stormwater samples were collected from six different land use sites with three time-intervals during a precipitation event on August 12, 2016, from a community of Beijing, China. A total of 46 species volatile organic compounds (VOCs) were detected in these stormwater samples, including methyl tertiary-butyl ether (MTBE), aromatic hydrocarbons, halogenated aromatics, Halogenated alkanes, and alkenes. The total VOC concentrations varied in the six sites following order: highway junction > city road > gas station > park > campus > residential area, except for MTBE, which was much higher at gas station compared to other land use sites. ANOVA results indicated both land use and precipitation time intervals could significantly affect the VOC concentrations even in the small area. The Beijing atmospheric VOC concentrations were too low to explain the high concentrations in stormwater, suggesting that land surfaces may be the main sources of VOC other than the ambient atmosphere. MTBE and other VOCs correlation analysis indicated that MTBE mostly came from gasoline emissions, spills or vehicle exhausts, whereas the BTEX (benzene, toluene, ethylbenzene, Xylenes) and the halogenated aromatics were transferred from chemical plants through land surfaces accumulating and the wind blowing atmospheric VOCs. Xylenes/ethylbenzene (X/E) ratios variations indicated that stormwater incorporated larger amount of fresh emitted air during the precipitation event than prior to it. Information of these stormwater VOCs in this study could be used in the community pollution reduction strategies. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Syntheses of halogen derivatives of L-tryptophan, L-tyrosine and L-phenylalanine labeled with hydrogen isotopes.

    PubMed

    Pająk, Małgorzata; Pałka, Katarzyna; Winnicka, Elżbieta; Kańska, Marianna

    2016-01-01

    Halogenated, labeled with tritium and doubly with deuterium and tritium, derivatives of L-tryptophan, i.e. 5'-bromo-[2-(3)H]-, 5'-bromo-[2-(2)H/(3)H]-, 5'-fluoro-[2-(3)H]-5'-fluoro-[2-(2)H/(3)H]-, 6'-fluoro-[2-(3)H]-, 6'-fluoro-[2-(2)H/(3)H]-L-tryptophan, as well as, L-tyrosine, i.e. 3'-fluoro-[2-(3)H]-, 3'-fluoro-[2-(2)H/(3)H]-, 3'-chloro-[2-(3)H]-, and 3'-chloro-[2-(2)H/(3)H]-L-tyrosine, and also L-phenylalanine, i.e. 2'-fluoro-[(3S)-(3)H]-, 2'-fluoro-[(3S)-(2)H/(3) H]-, 2'-chloro-[(3S)-(3)H]-, 2'-chloro-[(3S)-(2)H/(3)H]-, 4'-chloro-[(3S)-(3)H]-, and 4'-chloro-[(3S)-(2)H/(3)H]-L-phenylalanine were synthesized using enzymatic methods. Isotopomers of L-tryptophan were synthesized by coupling of halogenated indoles with S-methyl-L-cysteine carried out in deuteriated or tritiated incubation media. Labeled halogenated derivatives of L-tyrosine were obtained by the enzymatically supported exchange between halogenated L-tyrosine and isotopic water. Labeled halogenated isotopologues of L-Phe were synthesized by the enzymatic addition of ammonia to halogenated cinnamic acid. As a source of hydrogen tritiated water (HTO) and heavy water (D2O) with addition of HTO were used. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Comparison of halogen, plasma and LED curing units.

    PubMed

    Nomoto, Rie; McCabe, John F; Hirano, Susumu

    2004-01-01

    This study evaluated the characteristics of two kinds of recently developed light-curing unit; plasma arc and blue light emitting diodes (LED), in comparison with a conventional tungsten-halogen light-curing unit. The light intensity and spectral distribution of light from these light-curing units, the temperature rise of the bovine enamel surface and the depth of cure of composites exposed to each unit were investigated. The light intensity and depth of cure were determined according to ISO standards. The spectral distributions of emitted light were measured using a spectro-radiometer. The temperature increase induced by irradiation was measured by using a thermocouple. Generally, light intensities in the range 400-515 nm emitted from the plasma arc were greater than those from other types. Light in the UV-A region was emitted from some plasma arc units. The required irradiation times were six to nine seconds for the plasma arc units and 40 to 60 seconds for the LED units to create a depth of cure equal to that produced by the tungsten-halogen light with 20 seconds of irradiation. The temperature increased by increasing the irradiation time for every light-curing unit. The temperature increases were 15 degrees C to 60 degrees C for plasma arc units, around 15 degrees C for a conventional halogen unit and under 10 degrees C for LED units. Both the plasma arc and LED units required longer irradiation times than those recommended by their respective manufacturers. Clinicians should be aware of potential thermal rise and UV-A hazard when using plasma arc units.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Jin-Feng; Sun, Yin-Yin; Li, Miao-Miao

    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 overestimatesmore » 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.« less

  7. Co-exposure with fullerene may strengthen health effects of organic industrial chemicals.

    PubMed

    Lehto, Maili; Karilainen, Topi; Róg, Tomasz; Cramariuc, Oana; Vanhala, Esa; Tornaeus, Jarkko; Taberman, Helena; Jänis, Janne; Alenius, Harri; Vattulainen, Ilpo; Laine, Olli

    2014-01-01

    In vitro toxicological studies together with atomistic molecular dynamics simulations show that occupational co-exposure with C60 fullerene may strengthen the health effects of organic industrial chemicals. The chemicals studied are acetophenone, benzaldehyde, benzyl alcohol, m-cresol, and toluene which can be used with fullerene as reagents or solvents in industrial processes. Potential co-exposure scenarios include a fullerene dust and organic chemical vapor, or a fullerene solution aerosolized in workplace air. Unfiltered and filtered mixtures of C60 and organic chemicals represent different co-exposure scenarios in in vitro studies where acute cytotoxicity and immunotoxicity of C60 and organic chemicals are tested together and alone by using human THP-1-derived macrophages. Statistically significant co-effects are observed for an unfiltered mixture of benzaldehyde and C60 that is more cytotoxic than benzaldehyde alone, and for a filtered mixture of m-cresol and C60 that is slightly less cytotoxic than m-cresol. Hydrophobicity of chemicals correlates with co-effects when secretion of pro-inflammatory cytokines IL-1β and TNF-α is considered. Complementary atomistic molecular dynamics simulations reveal that C60 co-aggregates with all chemicals in aqueous environment. Stable aggregates have a fullerene-rich core and a chemical-rich surface layer, and while essentially all C60 molecules aggregate together, a portion of organic molecules remains in water.

  8. Hydrophobic Organic Compounds in Hydraulic Fracturing Flowback Waters: Identification and Source Apportionment

    NASA Astrophysics Data System (ADS)

    Plata, D.; Shregglman, K.; Elsner, M.; Getzinger, G.; Ferguson, L.; Drollette, B.; Karatum, O.; Nelson, R. K.; Reddy, C. M.

    2014-12-01

    Current hydraulic fracturing technologies rely on organic chemicals to serve multiple critical functions, including corrosion inhibition, in situ gel formation, and friction reduction. While industrial users have disclosed several hundreds of compound and mixture identities, it is unclear which of these are used and where, in what proportion, and with what frequency. Furthermore, while flowback and production waters contain both fracturing additive and geogenic compounds, they may contain potential reaction byproducts as well. Here, we identified several hundred organic compounds present in six hydraulic fracturing flowback waters over the Fayetteville shale. Identifications were made via non-target analysis using two-dimensional gas chromatography with time of flight mass spectrometry for hydrophobic organic compounds and liquid chromatography- orbitrap mass spectrometry. Compound identities were confirmed using purchased standards when available. Using the SkyTruth database and the Waxman list of disclosed compounds, we assigned compounds as either fracturing-fluid-derived or geogenic (or both), or a putative transformation products thereof. Several unreported halogenated compounds were detected, including chlorinated, brominated, and iodated species that have no known natural sources. Control studies indicated that these could not be formed under typical laboratory or field storage conditions, suggesting that halogenation reactions may give rise to novel compounds in the subsurface, presumably via reaction between fracturing fluid additives and shale-derived brines. Further, the six samples were strikingly heterogeneous, reflecting the diversity in fracturing fluid composition and flowback handling procedures at the time of the study.

  9. Temperature analysis during bonding of brackets using LED or halogen light base units.

    PubMed

    Silva, Paulo César Gomes; De Fátima Zanirato Lizarelli, Rosane; Moriyama, Lílian Tan; De Toledo Porto Neto, Sizenando; Bagnato, Vanderlei Salvador

    2005-02-01

    The purpose of our investigation is to compare the intrapulpal temperature changes following blue LED system and halogen lamp irradiation at the enamel surface of permanent teeth. The fixation of brackets using composite resin is more comfortable and faster when using a photo-curable composite. Several light sources can be used: halogens, arc plasma, lasers, and recently blue LED systems. An important aspect to be observed during such a procedures is the temperature change. In this study, we have used nine human extracted permanent teeth: three central incisors, three lateral incisors, and three canines. Teeth were exposed to two light sources: blue LED system (preliminary commercial model LEC 470-II) and halogen lamp (conventional photo-cure equipment). The surface of teeth was exposed for 20, 40, and 60 sec at the buccal and lingual enamel surface with an angle of 45 degrees. Temperature values measured by a thermistor placed at pulpar chamber were read in time intervals of 1 sec. We obtained plots showing the temperature evolution as a function of time for each experiment. There is a correlation between heating quantity and exposition time of light source: with increasing exposition time, heating increases into the pulpal chamber. The halogen lamp showed higher heating than the LED system, which showed a shorter time of cooling than halogen lamp. The blue LED system seems like the indicated light source for photo-cure of composite resin during the bonding of brackets. The fixation of brackets using composite resin is more comfortable and faster when using a photo-curable composite. Blue LED equipment did not heat during its use. This could permit a shorter clinical time of operation and better performance.

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

    PubMed

    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.

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

    PubMed

    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. Source identification and apportionment of halogenated compounds observed at a remote site in East Asia.

    PubMed

    Li, Shanlan; Kim, Jooil; Park, Sunyoung; Kim, Seung-Kyu; Park, Mi-Kyung; Mühle, Jens; Lee, Gangwoong; Lee, Meehye; Jo, Chun Ok; Kim, Kyung-Ryul

    2014-01-01

    The sources of halogenated compounds in East Asia associated with stratospheric ozone depletion and climate change are relatively poorly understood. High-precision in situ measurements of 18 halogenated compounds and carbonyl sulfide (COS) made at Gosan, Jeju Island, Korea, from November 2007 to December 2011 were analyzed by a positive matrix factorization (PMF). Seven major industrial sources were identified from the enhanced concentrations of halogenated compounds observed at Gosan and corresponding concentration-based source contributions were also suggested: primary aluminum production explaining 37% of total concentration enhancements, solvent usage of which source apportionment is 25%, fugitive emissions from HCFC/HFC production with 11%, refrigerant replacements (9%), semiconductor/electronics industry (9%), foam blowing agents (6%), and fumigation (3%). Statistical trajectory analysis was applied to specify the potential emission regions for seven sources using back trajectories. Primary aluminum production, solvent usage and fugitive emission sources were mainly contributed by China. Semiconductor/electronics sources were dominantly located in Korea. Refrigerant replacement, fumigation and foam blowing agent sources were spread throughout East Asian countries. The specified potential source regions are consistent with country-based consumptions and emission patterns, verifying the PMF analysis results. The industry-based emission sources of halogenated compounds identified in this study help improve our understanding of the East Asian countries' industrial contributions to halogenated compound emissions.

  13. Metal organic frameworks for the catalytic detoxification of chemical warfare nerve agents

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hupp, Joseph T.; Farha, Omar K.; Katz, Michael J.

    A method of using a metal organic framework (MOF) comprising a metal ion and an at least bidendate organic ligand to catalytically detoxify chemical warfare nerve agents including exposing the metal-organic-framework (MOF) to the chemical warfare nerve agent and catalytically decomposing the nerve agent with the MOF.

  14. 40 CFR 721.4484 - Halogenated indane (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Halogenated indane (generic name). 721.4484 Section 721.4484 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... into a plastic, resin matrix, or pelletized so humans are not reasonally likely to be exposed. (2) The...

  15. 40 CFR 721.4484 - Halogenated indane (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halogenated indane (generic name). 721.4484 Section 721.4484 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... into a plastic, resin matrix, or pelletized so humans are not reasonally likely to be exposed. (2) The...

  16. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Modified reaction products of alkyl... Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound... identified generically as modified reaction products of alkyl alcohol, halogenated alkane, substituted...

  17. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified reaction products of alkyl... Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound... identified generically as modified reaction products of alkyl alcohol, halogenated alkane, substituted...

  18. The influence of ocean halogen and sulfur emissions in the air quality of a coastal megacity: The case of Los Angeles.

    PubMed

    Muñiz-Unamunzaga, Maria; Borge, Rafael; Sarwar, Golam; Gantt, Brett; de la Paz, David; Cuevas, Carlos A; Saiz-Lopez, Alfonso

    2018-01-01

    The oceans are the main source of natural halogen and sulfur compounds, which have a significant influence on the oxidizing capacity of the marine atmosphere; however, their impact on the air quality of coastal cities is currently unknown. We explore the effect of marine halogens (Cl, Br and I) and dimethyl sulfide (DMS) on the air quality of a large coastal city through a set of high-resolution (4-km) air quality simulations for the urban area of Los Angeles, US, using the Community Multiscale Air Quality (CMAQ model). The results indicate that marine halogen emissions decrease ozone and nitrogen dioxide levels up to 5ppbv and 2.5ppbv, respectively, in the city of Los Angeles. Previous studies suggested that the inclusion of chlorine in air quality models leads to the generation of ozone in urban areas through photolysis of nitryl chloride (ClNO 2 ). However, we find that when considering the chemistry of Cl, Br and I together the net effect is a reduction of surface ozone concentrations. Furthermore, combined ocean emissions of halogens and DMS cause substantial changes in the levels of key urban atmospheric oxidants such as OH, HO 2 and NO 3 , and in the composition and mass of fine particles. Although the levels of ozone, NO 3 and HO x are reduced, we find a 10% increase in secondary organic aerosol (SOA) mean concentration, attributed to the increase in aerosol acidity and sulfate aerosol formation when combining DMS and bromine. Therefore, this new pathway for enhanced SOA formation may potentially help with current model under predictions of urban SOA. Although further observations and research are needed to establish these preliminary conclusions, this first city-scale investigation suggests that the inclusion of oceanic halogens and DMS in air quality models may improve regional air quality predictions over coastal cities around the world. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Novel halogen chemistry in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Plane, J. M.; Saiz-Lopez, A.; Shillito, J. A.

    2003-12-01

    This paper will report the first observations of I2 in the marine boundary layer, made by Differential Optical Absorption (DOAS) spectroscopy during a field campaign at Mace Head (Ireland) in the summer of 2002. Very large I2 concentrations correlating with low tide indicate that the source is emission from macro-algae. Simple scaling suggests that this coastal emission could approach 2 Tg per year, making it a major contribution to the global iodine budget. During the same campaign, DOAS observations were also made of the halogen oxides IO, OIO and BrO. The pulses of IO and BrO that were measured at sunrise are strong evidence for heterogeneous processing on sea-salt aerosol producing high levels of IBr during the night. Simple modelling shows that the observed concentrations of the halogen radicals will play important roles in ozone depletion, the oxidation of dimethyl sulfide, and the formation of new particles in the marine boundary layer.

  20. [Removal of AOX and Chroma in Biologically Treated Effluent of Chemical Dyestuff Wastewater with Nanoscale Ni/Fe].

    PubMed

    Shu, Xiao-ming; Xu, Can-can; Liu, Rui; Zhao, Yuan; Chen, Lü-jun

    2016-02-15

    Nanoscale Ni/Fe was applied to biologically treated effluent of chemical dyestuff wastewater. The removal rates of absorbable organic halogens (AOX) and chroma were investigated at different Ni loadings (0-5%), initial wastewater pH (4.1-10.0), Ni/Fe dosage (1-5 g x L(-1)) and reaction time (0.5-96 h). The results showed that the removal rates of AOX and chroma firstly increased and then decreased with the increase of the Ni loading, while continuously increased with the decrease of the initial wastewater pH and the increase of Ni/Fe dosage. The optimal condition was Ni loading of 1%, initial wastewater pH of 4.1 and Ni/Fe dosage of 3 g x L(-1), under which 29.2% of AOX and 79.6% of chroma were removed after 24 h reaction, and 50.6% of AOX and 80.7% of chroma were removed after 96 h reaction. GC-MS analysis revealed that toxicants such as chlorinated anilines, p-nitroaniline, 4-methoxy-2-nitroaniline and halogenated hydrocarbons were efficiently removed.

  1. Carotenoids Database: structures, chemical fingerprints and distribution among organisms

    PubMed Central

    2017-01-01

    Abstract To promote understanding of how organisms are related via carotenoids, either evolutionarily or symbiotically, or in food chains through natural histories, we built the Carotenoids Database. This provides chemical information on 1117 natural carotenoids with 683 source organisms. For extracting organisms closely related through the biosynthesis of carotenoids, we offer a new similarity search system ‘Search similar carotenoids’ using our original chemical fingerprint ‘Carotenoid DB Chemical Fingerprints’. These Carotenoid DB Chemical Fingerprints describe the chemical substructure and the modification details based upon International Union of Pure and Applied Chemistry (IUPAC) semi-systematic names of the carotenoids. The fingerprints also allow (i) easier prediction of six biological functions of carotenoids: provitamin A, membrane stabilizers, odorous substances, allelochemicals, antiproliferative activity and reverse MDR activity against cancer cells, (ii) easier classification of carotenoid structures, (iii) partial and exact structure searching and (iv) easier extraction of structural isomers and stereoisomers. We believe this to be the first attempt to establish fingerprints using the IUPAC semi-systematic names. For extracting close profiled organisms, we provide a new tool ‘Search similar profiled organisms’. Our current statistics show some insights into natural history: carotenoids seem to have been spread largely by bacteria, as they produce C30, C40, C45 and C50 carotenoids, with the widest range of end groups, and they share a small portion of C40 carotenoids with eukaryotes. Archaea share an even smaller portion with eukaryotes. Eukaryotes then have evolved a considerable variety of C40 carotenoids. Considering carotenoids, eukaryotes seem more closely related to bacteria than to archaea aside from 16S rRNA lineage analysis. Database URL: http://carotenoiddb.jp PMID:28365725

  2. Tailoring topological states in silicene using different halogen-passivated Si(111) substrates

    NASA Astrophysics Data System (ADS)

    Derakhshan, Vahid; Moghaddam, Ali G.; Ceresoli, Davide

    2018-03-01

    We investigate the band structure and topological phases of silicene embedded on halogenated Si(111) surface using density functional theory calculations. Our results show that the Dirac character of low-energy excitations in silicene is almost preserved in the presence of a silicon substrate passivated by various halogens. Nevertheless, the combined effects of symmetry breaking due to both direct and van der Waals interactions between silicene and the substrate, charge transfer from suspended silicene into the substrate, and, finally, the hybridization which leads to the charge redistribution result in a gap in the spectrum of the embedded silicene. We further take the spin-orbit interaction into account and obtain the resulting modification in the gap. The energy gaps with and without spin-orbit coupling vary significantly when different halogen atoms are used for the passivation of the Si surface, and for the case of iodine, they become on the order of 100 meV. To examine the topological properties, we calculate the projected band structure of silicene from which the Berry curvature and Z2 invariant based on the evolution of Wannier charge centers are obtained. As a key finding, it is shown that silicene on halogenated Si substrates has a topological insulating state which can survive even at room temperature for the substrates with iodine and bromine at the surface. Therefore, these results suggest that we can have a reliable, stable, and robust silicene-based two-dimensional topological insulator using the considered substrates.

  3. Method for selective dehalogenation of halogenated polyaromatic compounds

    DOEpatents

    Farcasiu, Malvina; Petrosius, Steven C.

    1994-01-01

    A method for dehalogenating halogenated polyaromatic compounds is provided wherein the polyaromatic compounds are mixed with a hydrogen donor solvent and a carbon catalyst in predetermined proportions, the mixture is maintained at a predetermined pressure, and the mixture is heated to a predetermined temperature and for a predetermined time.

  4. Photoproduction of halogens using platinized TiO2

    NASA Technical Reports Server (NTRS)

    Reichman, B.; Byvik, C. E.

    1981-01-01

    Unlike electrolysis of halide salt solutions, technique using powdered titanium dioxide catalyst requires no external power other than ultraviolet radiation source. Semiconductor powders photocatalyze and photosynthesize many useful reactions; applications are production of halogen molecules, oxidation of hazardous materials in wastewater, and conversion of carbon monoxide to carbon dioxide.

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

    PubMed

    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.

  6. Chemical transformation of iodate(IO3-) and nitrite(NO2-) in frozen solution and its environmental implications.

    NASA Astrophysics Data System (ADS)

    Kim, Kitae

    2017-04-01

    Ice is ubiquitous on earth and involved in various chemical reactions in the environment. Most chemical reactions are slowed down when temperature decreases according to Arrhenius equation. However, several chemical processes can be enhanced in frozen state. Reactive halogen species play important roles in the global environment. In particular, the presence of gaseous halogens in the polar and marine boundary layers is of great interest because these highly reactive species can affect ozone and mercury depletion events, oxidizing capacity, and DMS(dimethylsulfide) oxidation to form cloud-condensation nuclei. Among halogen compounds, the sources and emission mechanisms of inorganic iodine species in the polar region remain unclear. Iodide(I-) and iodate(IO3-) are the most dominant iodine species in nature and their chemical transformation or I-/IO3- ratio in frozen state remains poorly understood. Recent study shows that the production of active iodine compounds from frozen iodate salts during photochemical reaction. In previous study, nitrite(NO2-) oxidation to nitrate(NO3-), which is very slow reaction in aqueous solution, was significantly (105 times) accelerated in frozen state. The enhanced proton and oxygen concentration within ice grain boundaries are suspected that the enhanced oxidation of nitrite by freezing. Here we investigate chemical transformation of iodate/nitrite mixture in ice. The results show that the chemical reaction between iodate and nitrite in ice can potentially provide a new pathway for the source of reactive iodine species to the polar atmosphere. The detailed experimental conditions and mechanism will be discussed in the presentation.

  7. Halogen bonding, chalcogen bonding, pnictogen bonding, tetrel bonding: origins, current status and discussion.

    PubMed

    Brammer, Lee

    2017-10-13

    The role of the closing lecture in a Faraday Discussion is to summarise the contributions made to the Discussion over the course of the meeting and in so doing capture the main themes that have arisen. This article is based upon my Closing Remarks Lecture at the 203 rd Faraday Discussion meeting on Halogen Bonding in Supramolecular and Solid State Chemistry, held in Ottawa, Canada, on 10-12 th July, 2017. The Discussion included papers on fundamentals and applications of halogen bonding in the solid state and solution phase. Analogous interactions involving main group elements outside group 17 were also examined. In the closing lecture and in this article these contributions have been grouped into the four themes: (a) fundamentals, (b) beyond the halogen bond, (c) characterisation, and (d) applications. The lecture and paper also include a short reflection on past work that has a bearing on the Discussion.

  8. Halogen-Enriched Fragment Libraries as Leads for Drug Rescue of Mutant p53

    PubMed Central

    2012-01-01

    The destabilizing p53 cancer mutation Y220C creates a druggable surface crevice. We developed a strategy exploiting halogen bonding for lead discovery to stabilize the mutant with small molecules. We designed halogen-enriched fragment libraries (HEFLibs) as starting points to complement classical approaches. From screening of HEFLibs and subsequent structure-guided design, we developed substituted 2-(aminomethyl)-4-ethynyl-6-iodophenols as p53-Y220C stabilizers. Crystal structures of their complexes highlight two key features: (i) a central scaffold with a robust binding mode anchored by halogen bonding of an iodine with a main-chain carbonyl and (ii) an acetylene linker, enabling the targeting of an additional subsite in the crevice. The best binders showed induction of apoptosis in a human cancer cell line with homozygous Y220C mutation. Our structural and biophysical data suggest a more widespread applicability of HEFLibs in drug discovery. PMID:22439615

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

    NASA Astrophysics Data System (ADS)

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

    2018-06-01

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

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

    PubMed

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

    2016-12-30

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

  11. Room Temperature Halogenation of Polyimide Film Surface using Chlorine Trifluoride Gas

    NASA Astrophysics Data System (ADS)

    Habuka, Hitoshi; Kosuga, Takahiro; Koike, Kunihiko; Aida, Toshihiro; Takeuchi, Takashi; Aihara, Masahiko

    2004-02-01

    In order to develop a new application of chlorine trifluoride gas, the halogenation of a polyimide film surface at room temperature and at atmospheric pressure is studied for the first time. The polyimide film surface after exposure to the chlorine trifluoride gas shows a decreased water contact angle with increasing chlorine trifluoride gas concentration and exposure period. Since both X-ray photoelectron spectroscopy and infrared absorption spectroscopy simultaneously showed the formation of a carbon-chlorine bond and carbon-fluorine bond, it is concluded that the chlorine trifluoride gas can easily and safely perform the halogenation of the polyimide film surface under the stated conditions using a low-cost process and equipment.

  12. C-I···π Halogen Bonding Driven Supramolecular Helix of Bilateral N-Amidothioureas Bearing β-Turns.

    PubMed

    Cao, Jinlian; Yan, Xiaosheng; He, Wenbin; Li, Xiaorui; Li, Zhao; Mo, Yirong; Liu, Maili; Jiang, Yun-Bao

    2017-05-17

    We report the first example of C-I···π halogen bonding driven supramolecular helix in highly dilute solution of micromolar concentration, using alanine based bilateral I-substituted N-amidothioureas that contain helical fragments, the β-turn structures. The halogen bonding interactions afford head-to-tail linkages that help to propagate the helicity of the helical fragments. In support of this action of the halogen bonding, chiral amplification was observed in the supramolecular helix formed in acetonitrile solution. The present finding provides alternative tools in the design of self-assembling macromolecules.

  13. [Near infrared light irradiator using halogen lamp].

    PubMed

    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.

  14. Halogen and LED light curing of composite: temperature increase and Knoop hardness.

    PubMed

    Schneider, L F; Consani, S; Correr-Sobrinho, L; Correr, A B; Sinhoreti, M A

    2006-03-01

    This study assessed the Knoop hardness and temperature increase provided by three light curing units when using (1) the manufacturers' recommended times of photo-activation and (2) standardizing total energy density. One halogen--XL2500 (3M/ESPE)--and two light-emitting diode (LED) curing units--Freelight (3M/ESPE) and Ultrablue IS (DMC)--were used. A type-K thermocouple registered the temperature change produced by the composite photo-activation in a mold. Twenty-four hours after the photo-activation procedures, the composite specimens were submitted to a hardness test. Both temperature increase and hardness data were submitted to ANOVA and Tukey's test (5% significance). Using the first set of photo-activation conditions, the halogen unit produced a statistically higher temperature increase than did both LED units, and the Freelight LED resulted in a lower hardness than did the other curing units. When applying the second set of photo-activation conditions, the two LED units produced statistically greater temperature increase than did the halogen unit, whereas there were no statistical differences in hardness among the curing units.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. POSSIBLE MOLECULAR TARGETS OF HALOGENATED ARMOATIC HYDROCARBONS IN NEURONAL CELLS.

    EPA Science Inventory

    Halogenated aromatic hydrocarbons including polychlorinated biphenyls (PCBs) are persistent bioaccumulative toxicants. Due to these characteristics, there is considerable regulatory concern over the potential adverse health affects, especially to children, associated with exposur...

  17. Force Field Model of Periodic Trends in Biomolecular Halogen Bonds

    PubMed Central

    Scholfield, Matthew R.; Ford, Melissa Coates; Vander Zanden, Crystal M.; Billman, M. Marie; Ho, P. Shing; Rappé, Anthony K.

    2016-01-01

    The study of the noncovalent interaction now defined as a halogen bond (X-bond) has become one of the fastest growing areas in experimental and theoretical chemistry—its applications as a design tool are highly extensive. The significance of the interaction in biology has only recently been recognized, but has now become important in medicinal chemistry. We had previously derived a set of empirical potential energy functions to model the structure-energy relationships for bromines in biomolecular X-bonds (BXBs). Here, we have extended this force field for BXBs (ffBXB) to the halogens (Cl, Br, and I) that are commonly seen to form stable X-bonds. The ffBXB calculated energies show a remarkable one-to-one linear relationship to explicit BXB energies determined from an experimental DNA junction system, thereby validating the approach and the model. The resulting parameters allow us to interpret the stabilizing effects of BXBs in terms of well-defined physical properties of the halogen atoms, including their size, shape, and charge, showing periodic trends that are predictable along the Group VII column of elements. Consequently, we have established the ffBXB as accurate computational tool that can be applied to, for example, for the design of new therapeutic compounds against clinically important targets and new biomolecular based materials. PMID:25338128

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

    PubMed

    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.

  19. Biological Activity of Recently Discovered Halogenated Marine Natural Products

    PubMed Central

    Gribble, Gordon W.

    2015-01-01

    This review presents the biological activity—antibacterial, antifungal, anti-parasitic, antiviral, antitumor, antiinflammatory, antioxidant, and enzymatic activity—of halogenated marine natural products discovered in the past five years. Newly discovered examples that do not report biological activity are not included. PMID:26133553

  20. Mercury and halogens in coal: Chapter 2

    USGS Publications Warehouse

    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

  1. ON DEVELOPING CLEANER ORGANIC UNIT PROCESSES

    EPA Science Inventory

    Organic waste products, potentially harmful to the human health and the environment, are primarily produced in the synthesis stage of manufacturing processes. Many such synthetic unit processes, such as halogenation, oxidation, alkylation, nitration, and sulfonation are common to...

  2. Influence of the chemical structure on odor qualities and odor thresholds of halogenated guaiacol-derived odorants

    NASA Astrophysics Data System (ADS)

    Juhlke, Florian; Lorber, Katja; Wagenstaller, Maria; Buettner, Andrea

    2017-12-01

    Chlorinated guaiacol derivatives are found in waste water of pulp mills using chlorine in the bleaching process of wood pulp. They can also be detected in fish tissue, possibly causing off-odors. To date, there is no systematic investigation on the odor properties of halogenated guaiacol derivatives. To close this gap, odor thresholds in air and odor qualities of 14 compounds were determined by gas chromatography-olfactometry. Overall, the investigated compounds elicited smells that are characteristic for guaiacol, namely smoky, sweet, vanilla-like, but also medicinal and plaster-like. Their odor thresholds in air were, however, very low, ranging from 0.00072 to 23 ng/Lair. The lowest thresholds were found for 5-chloro- and 5-bromoguaiacol, followed by 4,5-dichloro- and 6-chloroguaiacol. Moreover, some inter-individual differences in odor threshold values could be observed, with the highest variations having been recorded for the individual values of 5-iodo- and 4-bromoguaiacol.

  3. AOX removal from industrial wastewaters using advanced oxidation processes: assessment of a combined chemical-biological oxidation.

    PubMed

    Luyten, J; Sniegowski, K; Van Eyck, K; Maertens, D; Timmermans, S; Liers, Sven; Braeken, L

    2013-01-01

    In this paper, the abatement of adsorbable halogenated organic compounds (AOX) from an industrial wastewater containing relatively high chloride concentrations by a combined chemical and biological oxidation is assessed. For chemical oxidation, the O(3)/UV, H(2)O(2)/UV and photo-Fenton processes are evaluated on pilot scale. Biological oxidation is simulated in a 4 h respirometry experiment with periodic aeration. The results show that a selective degradation of AOX with respect to the matrix compounds (expressed as chemical oxygen demand) could be achieved. For O(3)/UV, lowering the ratio of O(3) dosage to UV intensity leads to a better selectivity for AOX. During O(3)-based experiments, the AOX removal is generally less than during the H(2)O(2)-based experiments. However, after biological oxidation, the AOX levels are comparable. For H(2)O(2)/UV, optimal operating parameters for UV and H(2)O(2) dosage are next determined in a second run with another wastewater sample.

  4. Halogenated Solvent Cleaning: National Emission Standards for Hazardous Air Pollutants (NESHAP)

    EPA Pesticide Factsheets

    Learn about the Maximum Achievable Control Technology (MACT) standards for halogenated solvent cleaner. Find the rule history information, federal register citations, legal authority, and additional resources.

  5. Target organs in chronic bioassays of 533 chemical carcinogens

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gold, L.S.; Slone, T.H.; Manley, N.B.

    1991-06-01

    A compendium of carcinogenesis bioassay results organized by target organ is presented for 533 chemicals that are carcinogenic in at least one species. This compendium is based primarily on experiments in rats or mice; results in hamsters, nonhuman primates, and dogs are also reported. The compendium can be used to identify chemicals that induce tumors at particular sites, and to determine whether target sites are the same for chemicals positive in more than one species. The Carcinogenic Potency Database (CPDB), which includes results of 3969 experiments, is used in the analysis. The published CPDB includes details on each test, andmore » literature references. Chemical carcinogens are reported for 35 different target organs in rats or mice. More than 80% of the carcinogens in each of these species are positive in at least one of the 8 most frequent target sites; liver, lung, mammary gland, stomach, vascular system, kidney, hematopoietic system, and urinary bladder. An analysis is presented of how well one can predict the carcinogenic response in mice from results in rats, or vice versa. Among chemicals tested in both species, 76% of rat carcinogens are positive in mice, and 71% of mouse carcinogens are positive in rats. Prediction is less accurate to the same target site: 52% of rat carcinogens are positive in the same site in mice, and 48% of mouse carcinogens are positive in the same site in rats. The liver is the most frequent site in common between rats and mice.« less

  6. Five-year trends of selected halogenated flame retardants in the atmosphere of Northeast China.

    PubMed

    Li, Wen-Long; Liu, Li-Yan; Song, Wei-Wei; Zhang, Zi-Feng; Qiao, Li-Na; Ma, Wan-Li; Li, Yi-Fan

    2016-01-01

    This study collected 227 pairs of gas phase and particle phase air samples in a typical urban city of Northeast China from 2008 to 2013. Four alternative halogenated flame retardants for polybrominated diphenyl ethers (PBDEs) were analyzed, namely 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EHTBB), bis (2-ethylhexyl) tetrabromophthalate (BEHTBP), syn-dechlorane plus (syn-DP) and anti-dechlorane plus (anti-DP). The average concentrations for EHTBB and BEHTBP were 5.2 ± 20 and 30 ± 200 pg/m3, respectively, while for syn-DP and anti-DPwere 1.9±5.1 and 5.8±18 pg/m3, respectively. Generally, they were frequently detected in the particle phase, and the gas/particle partitioning suggested they were the maximum partition chemicals. The fractional abundance of EHTBB (fEHTBB) and syn-DP (fsyn)were comparablewith those in other studies. Strong local sources were identified based on the air parcel backward trajectories and the potential source contribution function. The concentrations of these chemicals were significantly increased during this sampling campaign, possibly suggesting their increasing usages from 2008 to 2013 in China.

  7. Post-synthetic halide conversion and selective halogen capture in hybrid perovskites† †Electronic supplementary information (ESI) available. CCDC 1048945–1048947. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc01135c

    PubMed Central

    Solis-Ibarra, D.; Smith, I. C.

    2015-01-01

    Reaction with halogen vapor allows us to post-synthetically exchange halides in both three- (3D) and two-dimensional (2D) organic–inorganic metal-halide perovskites. Films of 3D Pb–I perovskites cleanly convert to films of Pb–Br or Pb–Cl perovskites upon exposure to Br2 or Cl2 gas, respectively. This gas–solid reaction provides a simple method to produce the high-quality Pb–Br or Pb–Cl perovskite films required for optoelectronic applications. Reactivity with halogens can be extended to the organic layers in 2D metal-halide perovskites. Here, terminal alkene groups placed between the inorganic layers can capture Br2 gas through chemisorption to form dibromoalkanes. This reaction's selectivity for Br2 over I2 allows us to scrub Br2 to obtain high-purity I2 gas streams. We also observe unusual halogen transfer between the inorganic and organic layers within a single perovskite structure. Remarkably, the perovskite's crystallinity is retained during these massive structural rearrangements. PMID:29218171

  8. PREDICTING SOIL SORPTION COEFFICIENTS OF ORGANIC CHEMICALS USING A NEURAL NETWORK MODEL

    EPA Science Inventory

    The soil/sediment adsorption partition coefficient normalized to organic carbon (Koc) is extensively used to assess the fate of organic chemicals in hazardous waste sites. Several attempts have been made to estimate the value of Koc from chemical structure ...

  9. Organic chemicals jeopardize the health of freshwater ecosystems on the continental scale

    PubMed Central

    Malaj, Egina; von der Ohe, Peter C.; Grote, Matthias; Kühne, Ralph; Mondy, Cédric P.; Usseglio-Polatera, Philippe; Brack, Werner; Schäfer, Ralf B.

    2014-01-01

    Organic chemicals can contribute to local and regional losses of freshwater biodiversity and ecosystem services. However, their overall relevance regarding larger spatial scales remains unknown. Here, we present, to our knowledge, the first risk assessment of organic chemicals on the continental scale comprising 4,000 European monitoring sites. Organic chemicals were likely to exert acute lethal and chronic long-term effects on sensitive fish, invertebrate, or algae species in 14% and 42% of the sites, respectively. Of the 223 chemicals monitored, pesticides, tributyltin, polycyclic aromatic hydrocarbons, and brominated flame retardants were the major contributors to the chemical risk. Their presence was related to agricultural and urban areas in the upstream catchment. The risk of potential acute lethal and chronic long-term effects increased with the number of ecotoxicologically relevant chemicals analyzed at each site. As most monitoring programs considered in this study only included a subset of these chemicals, our assessment likely underestimates the actual risk. Increasing chemical risk was associated with deterioration in the quality status of fish and invertebrate communities. Our results clearly indicate that chemical pollution is a large-scale environmental problem and requires far-reaching, holistic mitigation measures to preserve and restore ecosystem health. PMID:24979762

  10. Predicting the bioconcentration factor of highly hydrophobic organic chemicals.

    PubMed

    Garg, Rajni; Smith, Carr J

    2014-07-01

    Bioconcentration refers to the process of uptake and buildup of chemicals in living organisms. Experimental measurement of bioconcentration factor (BCF) is time-consuming and expensive, and is not feasible for a large number of chemicals of regulatory concern. Quantitative structure-activity relationship (QSAR) models are used for estimating BCF values to help in risk assessment of a chemical. This paper presents the results of a QSAR study conducted to address an important problem encountered in the prediction of the BCF of highly hydrophobic chemicals. A new QSAR model is derived using a dataset of diverse organic chemicals previously tested in a United States Environmental Protection Agency laboratory. It is noted that the linear relationship between the BCF and hydrophobic parameter, i.e., calculated octanol-water partition coefficient (ClogP), breaks down for highly hydrophobic chemicals. The parabolic QSAR equation, log BCF=3.036 ClogP-0.197 ClogP(2)-0.808 MgVol (n=28, r(2)=0.817, q(2)=0.761, s=0.558) (experimental log BCF range=0.44-5.29, ClogP range=3.16-11.27), suggests that a non-linear relationship between BCF and the hydrophobic parameter, along with inclusion of additional molecular size, weight and/or volume parameters, should be considered while developing a QSAR model for more reliable prediction of the BCF of highly hydrophobic chemicals. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  11. 40 CFR 455.30 - Applicability; description of the metallo-organic pesticide chemicals manufacturing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... metallo-organic pesticide chemicals manufacturing subcategory. 455.30 Section 455.30 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS PESTICIDE CHEMICALS Metallo-Organic Pesticide Chemicals Manufacturing Subcategory § 455.30 Applicability; description of the...

  12. 40 CFR 455.30 - Applicability; description of the metallo-organic pesticide chemicals manufacturing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... metallo-organic pesticide chemicals manufacturing subcategory. 455.30 Section 455.30 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS PESTICIDE CHEMICALS Metallo-Organic Pesticide Chemicals Manufacturing Subcategory § 455.30 Applicability; description of the...

  13. Halogenated flame retardants in the Great Lakes environment.

    PubMed

    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

  14. A realistic chemical system presenting a self-organized critical behavior

    NASA Astrophysics Data System (ADS)

    Gaveau, Bernard; Latrémolière, Daniel; Moreau, Michel

    2003-04-01

    We consider a realistic example of chemical system which presents self-organized criticality. We can study the kinetic equations analytically, and show that the conditions for self-organized criticality are satisfied. We find power relaxation laws for certain variables near the critical state, confirming the self-organized critical behavior.

  15. Oxidation of hydrogen halides to elemental halogens

    DOEpatents

    Rohrmann, Charles A.; Fullam, Harold T.

    1985-01-01

    A process for oxidizing hydrogen halides having substantially no sulfur impurities by means of a catalytically active molten salt is disclosed. A mixture of the subject hydrogen halide and an oxygen bearing gas is contacted with a molten salt containing an oxidizing catalyst and alkali metal normal sulfates and pyrosulfates to produce an effluent gas stream rich in the elemental halogen and substantially free of sulfur oxide gases.

  16. 40 CFR 63.2465 - What requirements must I meet for process vents that emit hydrogen halide and halogen HAP or HAP...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

  17. 40 CFR 63.2465 - What requirements must I meet for process vents that emit hydrogen halide and halogen HAP or HAP...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

  18. 40 CFR 63.2465 - What requirements must I meet for process vents that emit hydrogen halide and halogen HAP or HAP...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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

  19. Organic Pollutants in Shale Gas Flowback and Produced Waters: Identification, Potential Ecological Impact, and Implications for Treatment Strategies.

    PubMed

    Butkovskyi, Andrii; Bruning, Harry; Kools, Stefan A E; Rijnaarts, Huub H M; Van Wezel, Annemarie P

    2017-05-02

    Organic contaminants in shale gas flowback and produced water (FPW) are traditionally expressed as total organic carbon (TOC) or chemical oxygen demand (COD), though these parameters do not provide information on the toxicity and environmental fate of individual components. This review addresses identification of individual organic contaminants in FPW, and stresses the gaps in the knowledge on FPW composition that exist so far. Furthermore, the risk quotient approach was applied to predict the toxicity of the quantified organic compounds for fresh water organisms in recipient surface waters. This resulted in an identification of a number of FPW related organic compounds that are potentially harmful namely those compounds originating from shale formations (e.g., polycyclic aromatic hydrocarbons, phthalates), fracturing fluids (e.g., quaternary ammonium biocides, 2-butoxyethanol) and downhole transformations of organic compounds (e.g., carbon disulfide, halogenated organic compounds). Removal of these compounds by FPW treatment processes is reviewed and potential and efficient abatement strategies are defined.

  20. Organic Pollutants in Shale Gas Flowback and Produced Waters: Identification, Potential Ecological Impact, and Implications for Treatment Strategies

    PubMed Central

    2017-01-01

    Organic contaminants in shale gas flowback and produced water (FPW) are traditionally expressed as total organic carbon (TOC) or chemical oxygen demand (COD), though these parameters do not provide information on the toxicity and environmental fate of individual components. This review addresses identification of individual organic contaminants in FPW, and stresses the gaps in the knowledge on FPW composition that exist so far. Furthermore, the risk quotient approach was applied to predict the toxicity of the quantified organic compounds for fresh water organisms in recipient surface waters. This resulted in an identification of a number of FPW related organic compounds that are potentially harmful namely those compounds originating from shale formations (e.g., polycyclic aromatic hydrocarbons, phthalates), fracturing fluids (e.g., quaternary ammonium biocides, 2-butoxyethanol) and downhole transformations of organic compounds (e.g., carbon disulfide, halogenated organic compounds). Removal of these compounds by FPW treatment processes is reviewed and potential and efficient abatement strategies are defined. PMID:28376616

  1. TOMS and SBUV Data: Comparison to 3D Chemical-Transport Model Results

    NASA Technical Reports Server (NTRS)

    Stolarski, Richard S.; Douglass, Anne R.; Steenrod, Steve; Frith, Stacey

    2003-01-01

    We have updated our merged ozone data (MOD) set using the TOMS data from the new version 8 algorithm. We then analyzed these data for contributions from solar cycle, volcanoes, QBO, and halogens using a standard statistical time series model. We have recently completed a hindcast run of our 3D chemical-transport model for the same years. This model uses off-line winds from the finite-volume GCM, a full stratospheric photochemistry package, and time-varying forcing due to halogens, solar uv, and volcanic aerosols. We will report on a parallel analysis of these model results using the same statistical time series technique as used for the MOD data.

  2. Influence of 5-HALOGENATION on the Structure of Protonated Uridine: Irmpd Action Spectroscopy and Theoretical Studies of the Protonated 5-HALOURIDINES

    NASA Astrophysics Data System (ADS)

    Roy, Harrison; Hamlow, Lucas; Lee, Justin; Rodgers, M. T.; Berden, Giel; Oomens, Jos

    2016-06-01

    The chemical and structural diversity and the extent of post-transcriptional modification of RNA is remarkable! Presently, there are 142 different naturally-occurring and many more synthetically modified nucleosides known. Uridine (Urd) is the most commonly modified nucleoside among those that occur naturally, but has also been an important target for synthesis and development of modified nucleosides for pharmaceutical applications. Indeed, modified nucleosides are of pharmaceutical interest due to their bioactivities. In particular, 5-bromouridine (br5Urd) has been shown to exhibit antiviral activity to human immunodeficiency virus and has been used in RNA labeling studies. Halogenation is a common modification employed in pharmaceutical studies that enables systematic variation is the electronic properties of the molecule of interest due to the availability of halogen substituents that vary in size, dipole moment, polarizability, and electron withdrawing properties. In order to elucidate the influence of 5-halogenation on the intrinsic gas-phase structure and stability on the protonated form of Urd, synergistic spectroscopic and theoretical studies of the protonated forms of the 5-halouridines are performed here, where x5Urd = 5-fluorouridine (f5Urd), 5-chlorouridine (cl5Urd), br5Urd, and 5-iodouridine (i5Urd). Infrared multiple photon dissociation (IRMPD) action spectra of the protonated forms of the 5-halouridines, [x5Urd+H]+, are measured over the IR fingerprint region using the FELIX free electron laser and the hydrogen stretching region using an OPO/OPA laser from 3300-3800 wn. Complementary electronic structure calculations are performed to determine the stable low-energy conformations available to these species and to predict their IR spectra. Comparative analyses of the measured IRMPD spectra and predicted IR spectra are performed to elucidate the preferred sites of protonation, and the low-energy tautomeric conformations that are populated by

  3. Channel-resolved photo- and Auger-electron spectroscopy of halogenated hydrocarbons

    NASA Astrophysics Data System (ADS)

    Ablikim, Utuq; Kaderiya, B.; Kumarapan, V.; Kushawaha, R.; Rudenko, A.; Rolles, D.; Xiong, H.; Berrah, N.; Bomme, C.; Savelyev, E.; Kilcoyne, D.

    2016-05-01

    Inner-shell photoelectron and Auger electron spectra of polyatomic molecules such as halogenated hydrocarbons are typically hard to interpret and assign due to many overlapping states that form broad bands even in high-resolution measurements. With the help of electron-ion-ion coincidence measurements performed using the velocity map imaging technique, we are able to detect high-energy (<= 150 eV) photo- and Auger electrons in coincidence with two- or many-body ionic fragmentation channels. Such channel-resolved measurements allow disentangling the overlapping electronic structures and help assigning individual components of the electron spectra to specific potential surfaces and final states. In this work, we present measurements on CH3 I, CH2 IBr, and CH2 ICl molecules in the gas-phase using soft x-ray light provided by the Advanced Light Source at LBNL. This project is supported by the DOE, Office of Science, BES, Division of Chemical, Geological and Biological Sciences under Award Number DE-FG02-86ER13491 (U.A., B.K., V.K., A.R., D.R.) and Award Number DE-SC0012376 (H.X., N.B.).

  4. 15 CFR Supplement No. 1 to Part 715 - Definition of an Unscheduled Discrete Organic Chemical

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Organic Chemical No. Supplement No. 1 to Part 715 Commerce and Foreign Trade Regulations Relating to... WEAPONS CONVENTION REGULATIONS ACTIVITIES INVOLVING UNSCHEDULED DISCRETE ORGANIC CHEMICALS (UDOCs) Pt. 715, Supp. 1 Supplement No. 1 to Part 715—Definition of an Unscheduled Discrete Organic Chemical Unscheduled...

  5. 78 FR 37222 - Columbia Organic Chemical Company Site, Columbia, Richland County, South Carolina; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-20

    ... ENVIRONMENTAL PROTECTION AGENCY [FRL-9826-7; CERCLA-04-2013-3761] Columbia Organic Chemical... Agency has entered into a settlement with Stephen Reichlyn concerning the Columbia Organic Chemical... comments by site name Columbia Organic Chemical Company by one of the following methods: www.epa.gov...

  6. 15 CFR Supplement No. 1 to Part 715 - Definition of an Unscheduled Discrete Organic Chemical

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Organic Chemical No. Supplement No. 1 to Part 715 Commerce and Foreign Trade Regulations Relating to... WEAPONS CONVENTION REGULATIONS ACTIVITIES INVOLVING UNSCHEDULED DISCRETE ORGANIC CHEMICALS (UDOCs) Pt. 715, Supp. 1 Supplement No. 1 to Part 715—Definition of an Unscheduled Discrete Organic Chemical Unscheduled...

  7. 15 CFR Supplement No. 1 to Part 715 - Definition of an Unscheduled Discrete Organic Chemical

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Organic Chemical No. Supplement No. 1 to Part 715 Commerce and Foreign Trade Regulations Relating to... WEAPONS CONVENTION REGULATIONS ACTIVITIES INVOLVING UNSCHEDULED DISCRETE ORGANIC CHEMICALS (UDOCs) Pt. 715, Supp. 1 Supplement No. 1 to Part 715—Definition of an Unscheduled Discrete Organic Chemical Unscheduled...

  8. 15 CFR Supplement No. 1 to Part 715 - Definition of an Unscheduled Discrete Organic Chemical

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Organic Chemical No. Supplement No. 1 to Part 715 Commerce and Foreign Trade Regulations Relating to... WEAPONS CONVENTION REGULATIONS ACTIVITIES INVOLVING UNSCHEDULED DISCRETE ORGANIC CHEMICALS (UDOCs) Pt. 715, Supp. 1 Supplement No. 1 to Part 715—Definition of an Unscheduled Discrete Organic Chemical Unscheduled...

  9. Evaluating gas chromatography with a halogen-specific detector for the determination of disinfection by-products in drinking water.

    PubMed

    Andersson, Anna; Ashiq, Muhammad Jamshaid; Shoeb, Mohammad; Karlsson, Susanne; Bastviken, David; Kylin, Henrik

    2018-02-28

    The occurrence of disinfection by-products (DBPs) in drinking water has become an issue of concern during the past decades. The DBPs pose health risks and are suspected to cause various cancer forms, be genotoxic, and have negative developmental effects. The vast chemical diversity of DBPs makes comprehensive monitoring challenging. Only few of the DBPs are regulated and included in analytical protocols. In this study, a method for simultaneous measurement of 20 DBPs from five different structural classes (both regulated and non-regulated) was investigated and further developed for 11 DBPs using solid-phase extraction and gas chromatography coupled with a halogen-specific detector (XSD). The XSD was highly selective towards halogenated DBPs, providing chromatograms with little noise. The method allowed detection down to 0.05 μg L -1 and showed promising results for the simultaneous determination of a range of neutral DBP classes. Compounds from two classes of emerging DBPs, more cytotoxic than the "traditional" regulated DBPs, were successfully determined using this method. However, haloacetic acids (HAAs) should be analyzed separately as some HAA methyl esters may degrade giving false positives of trihalomethanes (THMs). The method was tested on real water samples from two municipal waterworks where the target DBP concentrations were found below the regulatory limits of Sweden.

  10. On the physical nature of halogen bonds: a QTAIM study.

    PubMed

    Syzgantseva, Olga A; Tognetti, Vincent; Joubert, Laurent

    2013-09-12

    In this article, we report a detailed study on halogen bonds in complexes of CHCBr, CHCCl, CH2CHBr, FBr, FCl, and ClBr with a set of Lewis bases (NH3, OH2, SH2, OCH2, OH(-), Br(-)). To obtain insight into the physical nature of these bonds, we extensively used Bader's Quantum Theory of Atoms-in-Molecules (QTAIM). With this aim, in addition to the examination of the bond critical points properties, we apply Pendás' Interacting Quantum Atoms (IQA) scheme, which enables rigorous and physical study of each interaction at work in the formation of the halogen-bonded complexes. In particular, the influence of primary and secondary interactions on the stability of the complexes is analyzed, and the roles of electrostatics and exchange are notably discussed and compared. Finally, relationships between QTAIM descriptors and binding energies are inspected.

  11. Distribution of volatile organic chemicals in outdoor and indoor air

    NASA Technical Reports Server (NTRS)

    Shah, Jitendra J.; Singh, Hanwant B.

    1988-01-01

    The EPA volatile organic chemistry (VOC) national ambient data base (Shah, 1988) is discussed. The 320 chemicals included in the VOC data base are listed. The methods used to obtain the data are reviewed and the availability, accessibility, and operation of the data base are examined. Tables of the daily outdoor concentrations for 66 chemicals and the daily indoor concentrations for 35 chemicals are presented.

  12. Measuring indigenous photosynthetic organisms to detect chemical warefare agents in water

    DOEpatents

    Greenbaum, Elias; Sanders, Charlene A.

    2005-11-15

    A method of testing water to detect the presence of a chemical or biological warfare agent is disclosed. The method is carried out by establishing control data by providing control water containing indigenous organisms but substantially free of a chemical and a biological warfare agent. Then measuring photosynthetic activity of the control water with a fluorometer to obtain control data to compare with test data to detect the presence of the chemical or agent. The test data is gathered by providing test water comprising the same indigenous organisms as contained in the control water. Further, the test water is suspected of containing the chemical or agent to be tested for. Photosynthetic activity is also measured by fluorescence induction in the test water using a fluorometer.

  13. MIXTURES OF THYROID DISRUPTING CHEMICALS: TESTING ADDITIVITY OF HEPATIC INDUCERS AND THYROID PEROXIDASE INHIBITORS.

    EPA Science Inventory

    Humans are exposed to chemical mixtures via diet, occupation, and the environment. Previous data demonstrated that low doses of polycyclic halogenated aromatic hydrocarbons (PHAHs) acting through similar mechanisms result in an additive reduction of thyroxine (T4). If xenobioti...

  14. Pharmaceuticals and other organic chemicals in selected north-central and northwestern Arkansas streams

    USGS Publications Warehouse

    Haggard, B.E.; Galloway, J.M.; Green, W.R.; Meyer, M.T.

    2006-01-01

    Recently, our attention has focused on the low level detection of many antibiotics, pharmaceuticals, and other organic chemicals in water resources. The limited studies available suggest that urban or rural streams receiving wastewater effluent are more susceptible to contamination. The purpose of this study was to evaluate the occurrence of antibiotics, pharmaceuticals, and other organic chemicals at 18 sites on seven selected streams in Arkansas, USA, during March, April, and August 2004. Water samples were collected upstream and downstream from the influence of effluent discharges in northwestern Arkansas and at one site on a relatively undeveloped stream in north-central Arkansas. At least one antibiotic, pharmaceutical, or other organic chemical was detected at all sites, except at Spavinaw Creek near Mayesville, Arkansas. The greatest number of detections was observed at Mud Creek downstream from an effluent discharge, including 31 pharmaceuticals and other organic chemicals. The detection of these chemicals occurred in higher frequency at sites downstream from effluent discharges compared to those sites upstream from effluent discharges; total chemical concentration was also greater downstream. Wastewater effluent discharge increased the concentrations of detergent metabolites, fire retardants, fragrances and flavors, and steroids in these streams. Antibiotics and associated degradation products were only found at two streams downstream from effluent discharges. Overall, 42 of the 108 chemicals targeted in this study were found in water samples from at least one site, and the most frequently detected organic chemicals included caffeine, phenol, para-cresol, and acetyl hexamethyl tetrahydro naphthalene (AHTN). ?? ASA, CSSA, SSSA.

  15. REMOVAL OF URANIUM FROM ORGANIC LIQUIDS

    DOEpatents

    Vavalides, S.P.

    1959-08-25

    A process is described for recovering small quantities of uranium from organic liquids such as hydrocarbon oils. halogen-substituted hydrocarbons, and alcohols. The organic liquid is contacted with a comminuted alkaline earth hydroxide, calcium hydroxide particularly, and the resulting uranium-bearing solid is separated from the liquid by filtration. Uranium may then be recovered from the solid by means of dissolution in nitric acid and conventional extraction with an organic solvent such as tributyl phosphate.

  16. A Continued Study of Polymeric Materials for Protection Against Chemical and Biological Contaminants and Halogen Oxidants for Immobilization in Protective Materials and Coatings

    DTIC Science & Technology

    2013-03-01

    household bleach in water at a pH controlled at 7–10, or in a dilute solution of bromine. The loading of the halogen on the coatings was determined using ...or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process...disclosed, or represents that its use would not infringe privately owned rights. Standard Form 298 (Rev. 8/98) REPORT DOCUMENTATION PAGE Prescribed

  17. Computing chemical organizations in biological networks.

    PubMed

    Centler, Florian; Kaleta, Christoph; di Fenizio, Pietro Speroni; Dittrich, Peter

    2008-07-15

    Novel techniques are required to analyze computational models of intracellular processes as they increase steadily in size and complexity. The theory of chemical organizations has recently been introduced as such a technique that links the topology of biochemical reaction network models to their dynamical repertoire. The network is decomposed into algebraically closed and self-maintaining subnetworks called organizations. They form a hierarchy representing all feasible system states including all steady states. We present three algorithms to compute the hierarchy of organizations for network models provided in SBML format. Two of them compute the complete organization hierarchy, while the third one uses heuristics to obtain a subset of all organizations for large models. While the constructive approach computes the hierarchy starting from the smallest organization in a bottom-up fashion, the flux-based approach employs self-maintaining flux distributions to determine organizations. A runtime comparison on 16 different network models of natural systems showed that none of the two exhaustive algorithms is superior in all cases. Studying a 'genome-scale' network model with 762 species and 1193 reactions, we demonstrate how the organization hierarchy helps to uncover the model structure and allows to evaluate the model's quality, for example by detecting components and subsystems of the model whose maintenance is not explained by the model. All data and a Java implementation that plugs into the Systems Biology Workbench is available from http://www.minet.uni-jena.de/csb/prj/ot/tools.

  18. Uptake and mobilization of organic chemicals with clouds: evidence from a hail sample.

    PubMed

    Ma, Jianmin; Sverko, Ed; Su, Yushan; Zhang, Junhua; Gao, Hong

    2013-09-03

    Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were measured in hail samples collected during a storm that occurred on a spring morning in Toronto, Canada. The presence of these organic chemicals in hail suggests that clouds likely provide an atmospheric transport pathway for these substances in the free atmosphere. Results reported here may carry significant implications for atmospheric transport, mass balance, tropospheric cold trapping, and environmental fate of organic chemicals. Backward trajectories along with measured and modeled cloud cover show that clouds causing the hail event were formed and advected from the midwestern and southeastern United States. After being emitted to the atmosphere, the organic chemicals were likely lifted by atmospheric ascending motions to a higher atmospheric elevation and partitioned onto clouds. These clouds then carry the organic chemicals to a downwind location where they are deposited to the ground surface via precipitation. We found that the organic chemicals with high solubility and vapor pressure tend to partition into clouds through sorption to cloudwater droplets and ice particles. It was found that approximately 7-30% of pyrene could be sorbed into cloudwater droplets and ice particles in this hail event at the expense of reduced gas-phase concentrations.

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

    NASA Astrophysics Data System (ADS)

    Rammohan, A.; Kumar, C. Ramesh

    2017-11-01

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

  20. Spectroscopic detection of halogen bonding resolves dye regeneration in the dye-sensitized solar cell.

    PubMed

    Parlane, Fraser G L; Mustoe, Chantal; Kellett, Cameron W; Simon, Sarah J; Swords, Wesley B; Meyer, Gerald J; Kennepohl, Pierre; Berlinguette, Curtis P

    2017-11-24

    The interactions between a surface-adsorbed dye and a soluble redox-active electrolyte species in the dye-sensitized solar cell has a significant impact on the rate of regeneration of photo-oxidized dye molecules and open-circuit voltage of the device. Dyes must therefore be designed to encourage these interfacial interactions, but experimentally resolving how such weak interactions affect electron transfer is challenging. Herein, we use X-ray absorption spectroscopy to confirm halogen bonding can exist at the dye-electrolyte interface. Using a known series of triphenylamine-based dyes bearing halogen substituents geometrically positioned for reaction with halides in solution, halogen bonding was detected only in cases where brominated and iodinated dyes were photo-oxidized. This result implies that weak intermolecular interactions between photo-oxidized dyes and the electrolyte can impact device photovoltages. This result was unexpected considering the low concentration of oxidized dyes (less than 1 in 100,000) under full solar illumination.

  1. Regional atmospheric emissions determined from measurements at Jeju Island, Korea: Halogenated compounds from China

    NASA Astrophysics Data System (ADS)

    Kim, Jooil; Li, Shanlan; Kim, Kyung-Ryul; Stohl, Andreas; Mühle, Jens; Kim, Seung-Kyu; Park, Mi-Kyung; Kang, Dong-Jin; Lee, Gangwoong; Harth, Christina M.; Salameh, Peter K.; Weiss, Ray F.

    2010-06-01

    High-frequency in-situ measurements of a wide range of halogenated compounds including chlorofluorocarbons (CFCs), halons, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorinated compounds (PFCs), sulfur hexafluoride (SF6), and other chlorinated and brominated compounds have been made at Gosan (Jeju Island, Korea). Regional emissions of HCFC-22 (CHClF2) calculated from inverse modeling were combined with interspecies correlation methods to estimate national emissions for China, a major emitter of industrial halogenated gases. Our results confirm the signs of successful phase-out of primary ozone-depleting species such as CFCs, halons and many chlorinated or brominated compounds, along with substantial emissions of replacement HCFCs. Emissions derived for HFCs, PFCs, and SF6 were compared to published estimates and found to be a significant fraction of global totals. Overall, Chinese emissions of the halogenated compounds discussed here represent 19(14-17)% and 20(15-26)% of global emissions when evaluated in terms of their Ozone Depletion Potentials and 100-year Global Warming Potentials, respectively.

  2. Comparative developmental toxicity of new aromatic halogenated DBPs in a chlorinated saline sewage effluent to the marine polychaete Platynereis dumerilii.

    PubMed

    Yang, Mengting; Zhang, Xiangru

    2013-10-01

    Using seawater for toilet flushing may introduce high levels of bromide and iodide into a city's sewage treatment works, and result in the formation of brominated and iodinated disinfection byproducts (DBPs) during chlorination to disinfect sewage effluents. In a previous study, the authors' group has detected the presence of many brominated DBPs and identified five new aromatic brominated DBPs in chlorinated saline sewage effluents. The presence of brominated DBPs in chlorinated saline effluents may pose adverse implications for marine ecology. In this study, besides the detection and identification of another seven new aromatic halogenated DBPs in a chlorinated saline sewage effluent, their developmental toxicity was evaluated using the marine polychaete Platynereis dumerilii. For comparison, the developmental toxicity of some commonly known halogenated DBPs was also examined. The rank order of the developmental toxicity of 20 halogenated DBPs was 2,5-dibromohydroquinone > 2,6-diiodo-4-nitrophenol ≥ 2,4,6-triiodophenol > 4-bromo-2-chlorophenol ≥ 4-bromophenol > 2,4-dibromophenol ≥ 2,6-dibromo-4-nitrophenol > 2-bromo-4-chlorophenol > 2,6-dichloro-4-nitrophenol > 2,4-dichlorophenol > 2,4,6-tribromophenol > 3,5-dibromo-4-hydroxybenzaldehyde > bromoform ≥ 2,4,6-trichlorophenol > 2,6-dibromophenol > 2,6-dichlorophenol > iodoacetic acid ≥ tribromoacetic acid > bromoacetic acid > chloroacetic acid. On the basis of developmental toxicity data, a quantitative structure-activity relationship (QSAR) was established. The QSAR involved two physical-chemical property descriptors (log P and pKa) and two electronic descriptors (the lowest unoccupied molecular orbital energy and the highest occupied molecular orbital energy) to indicate the transport, biouptake, and biointeraction of these DBPs. It can well predict the developmental toxicity of most of the DBPs tested.

  3. CTEPP-OH DATA ANALYTICAL RESULTS ORGANIZED BY CHEMICAL AND MEDIA

    EPA Science Inventory

    This data set contains the field sample data by chemical and matrix for CTEPP-OH. The data is organized at the sample, chemical level.

    The Children’s Total Exposure to Persistent Pesticides and Other Persistent Pollutant (CTEPP) study was one of the largest aggregate exposure ...

  4. CTEPP NC DATA ANALYTICAL RESULTS ORGANIZED BY CHEMICAL AND MEDIA

    EPA Science Inventory

    This data set contains the field sample data by chemical and matrix. The data are organized at the sample, chemical level.

    The Children’s Total Exposure to Persistent Pesticides and Other Persistent Pollutant (CTEPP) study was one of the largest aggregate exposure studies of y...

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

    PubMed

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

    2011-05-01

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

  6. Role of halogen and hydrogen bonds for stabilization of antithyroid drugs with hypohalous acids (HOX, X = I, Br, and Cl) adducts

    NASA Astrophysics Data System (ADS)

    El-Sheshtawy, Hamdy S.; El-Mehasseb, Ibrahim

    2017-11-01

    The mechanism for the inhibition of thyroid hormones by the thioamide-like antithyroid drug is a key process in the thyroid gland function. Therefore, in this study theoretical investigation of the molecular interaction between two antithyroid drugs, namely methimazol (MMI) and thiazoline-2-thione (T2T), with the hypohalous acids (HOX, X = I, Br, and Cl), which act as heme-linked halogenated species to tyrosine residue was discussed. The calculations were performed by M06-2X and MP2 using aug-cc-pVDZ level of theory. In addition, wB97xd/6-31G* level of theory was used in order to account for the dispersion forces. The results show the possible formation of three adducts, which is stabilized by halogen bond (I), both halogen and hydrogen bonds (II), two hydrogen bonds (III). The binding energies of the complexes reveals stabilization in the order III > II > I. The binding energies of the complexes was increased with increasing the electron affinity and polarizability of halogen atom, the dipole moment of the complexes (I and II), the electrostatic potential on halogen atom (Vmax:i.e σ-hole), and the charge-transfer process through the halogen bond in I. On the other hand, the binding energies of the complexes decreased with increasing the halogen atom electronegativity and the dipole moment of complex III. Natural bond orbital (NBO) analysis was used to investigate the molecular orbital interactions and the charge transfer process upon complexation.

  7. Halogen bonds in some dihalogenated phenols: applications to crystal engineering.

    PubMed

    Mukherjee, Arijit; Desiraju, Gautam R

    2014-01-01

    3,4-Dichlorophenol (1) crystallizes in the tetragonal space group I41/a with a short axis of 3.7926 (9) Å. The structure is unique in that both type I and type II Cl⋯Cl interactions are present, these contact types being distinguished by the angle ranges of the respective C-Cl⋯Cl angles. The present study shows that these two types of contacts are utterly different. The crystal structures of 4-bromo-3-chlorophenol (2) and 3-bromo-4-chlorophenol (3) have been determined. The crystal structure of (2) is isomorphous to that of (1) with the Br atom in the 4-position participating in a type II interaction. However, the monoclinic P21/c packing of compound (3) is different; while the structure still has O-H⋯O hydrogen bonds, the tetramer O-H⋯O synthon seen in (1) and (2) is not seen. Rather than a type I Br⋯Br interaction which would have been mandated if (3) were isomorphous to (1) and (2), Br forms a Br⋯O contact wherein its electrophilic character is clearly evident. Crystal structures of the related compounds 4-chloro-3-iodophenol (4) and 3,5-dibromophenol (5) were also determined. A computational survey of the structural landscape was undertaken for (1), (2) and (3), using a crystal structure prediction protocol in space groups P21/c and I41/a with the COMPASS26 force field. While both tetragonal and monoclinic structures are energetically reasonable for all compounds, the fact that (3) takes the latter structure indicates that Br prefers type II over type I contacts. In order to differentiate further between type I and type II halogen contacts, which being chemically distinct are expected to have different distance fall-off properties, a variable-temperature crystallography study was performed on compounds (1), (2) and (4). Length variations with temperature are greater for type II contacts compared with type I. The type II Br⋯Br interaction in (2) is stronger than the corresponding type II Cl⋯Cl interaction in (1), leading to elastic bending

  8. Influence of Selected Organic Micropollutants on Organisms

    NASA Astrophysics Data System (ADS)

    Włodarczyk-Makuła, Maria

    2017-03-01

    This article describes the toxicity of organic micropollutants on tested microorganisms. Itis a current issue because organic micropollutants are identified in all elements of environmental (surface water, ground water, soils) and in food products. The organic micropollutants include: polychlorinated dibenzodioxyns PCDD, polychlorinated dibenzofurans PCDF, polychlorinated biphenyls PCB, polycyclic aromatic hydrocarbons PAH, halogenated compounds and by-products of water treatment. Some organic compounds cause hazard for health and human life due to their estrogenic biological activity, carcinogenic, mutagenic or teratogenic activity. The influence on organisms indicators of these compounds based on literature data were presented. The level of TEQ (toxic equivalency) in response to organic chlorine derivatives (PCDDs, PCDF, PCBs) is usually determined by toxic equivalency factor (TEF). The International Agency for Research on Cancer classifies organic micropollutants as carcinogenic to humans (Group 1), possibly carcinogenic (Group 2A) or probably carcinogenic to humans (Group 2B).

  9. Apparatus for sensing volatile organic chemicals in fluids

    DOEpatents

    Hughes, Robert C.; Manginell, Ronald P.; Jenkins, Mark W.; Kottenstette, Richard; Patel, Sanjay V.

    2005-06-07

    A chemical-sensing apparatus is formed from the combination of a chemical preconcentrator which sorbs and concentrates particular volatile organic chemicals (VOCs) and one or more chemiresistors that sense the VOCs after the preconcentrator has been triggered to release them in concentrated form. Use of the preconcentrator and chemiresistor(s) in combination allows the VOCs to be detected at lower concentration than would be possible using the chemiresistor(s) alone and further allows measurements to be made in a variety of fluids, including liquids (e.g. groundwater). Additionally, the apparatus provides a new mode of operation for sensing VOCs based on the measurement of decay time constants, and a method for background correction to improve measurement precision.

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

    PubMed

    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.

  11. DFT +U Modeling of Hole Polarons in Organic Lead Halide Perovskites

    NASA Astrophysics Data System (ADS)

    Welch, Eric; Erhart, Paul; Scolfaro, Luisa; Zakhidov, Alex

    Due to the ever present drive towards improved efficiencies in solar cell technology, new and improved materials are emerging rapidly. Organic halide perovskites are a promising prospect, yet a fundamental understanding of the organic perovskite structure and electronic properties is missing. Particularly, explanations of certain physical phenomena, specifically a low recombination rate and high mobility of charge carriers still remain controversial. We theoretically investigate possible formation of hole polarons adopting methodology used for oxide perovskites. The perovskite studied here is the ABX3structure, with A being an organic cation, B lead and C a halogen; the combinations studied allow for A1,xA2 , 1 - xBX1,xX2 , 3 - xwhere the alloy convention is used to show mixtures of the organic cations and/or the halogens. Two organic cations, methylammonium and formamidinium, and three halogens, iodine, chlorine and bromine are studied. Electronic structures and polaron behavior is studied through first principle density functional theory (DFT) calculations using the Vienna Ab Initio Simulation Package (VASP). Local density approximation (LDA) pseudopotentials are used and a +U Hubbard correction of 8 eV is added; this method was shown to work with oxide perovskites. It is shown that a localized state is realized with the Hubbard correction in systems with an electron removed, residing in the band gap of each different structure. Thus, hole polarons are expected to be seen in these perovskites.

  12. Modulation of persistent organic pollutant toxicity through nutritional intervention: emerging opportunities in biomedicine and environmental remediation.

    PubMed

    Petriello, Michael C; Newsome, Bradley J; Dziubla, Thomas D; Hilt, J Zach; Bhattacharyya, Dibakar; Hennig, Bernhard

    2014-09-01

    Environmental pollution is increasing worldwide, and there is evidence that exposure to halogenated persistent organic pollutants (POPs) such as polychlorinated biphenyls can contribute to the pathology of inflammatory diseases such as atherosclerosis, diabetes, and cancer. Pollutant removal from contaminated sites and subsequent pollutant degradation are critical for reducing the long-term health risks associated with exposure. However, complete remediation of a toxicant from the environment is very difficult and cost-prohibitive. Furthermore, remediation technologies often result in the generation of secondary toxicants. Considering these circumstances, environmentally-friendly and sustainable remediation technologies and biomedical solutions to reduce vulnerability to environmental chemical insults need to be explored to reduce the overall health risks associated with exposure to environmental pollutants. We propose that positive lifestyle changes such as healthful nutrition and consumption of diets rich in fruits and vegetables or bioactive nutrients with antioxidant and/or anti-inflammatory properties will reduce the body's vulnerability to environmental stressors and thus reduce toxicant-mediated disease pathologies. Interestingly, emerging evidence now implicates the incorporation of bioactive nutrients, such as plant-derived polyphenols, in technologies focused on the capture, sensing and remediation of halogenated POPs. We propose that human nutritional intervention in concert with the use of natural polyphenol sensing and remediation platforms may provide a sensible means to develop primary and long-term prevention strategies of diseases associated with many environmental toxic insults including halogenated POPs. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Modulation of persistent organic pollutant toxicity through nutritional intervention: emerging opportunities in biomedicine and environmental remediation

    PubMed Central

    Petriello, Michael C.; Newsome, Bradley J.; Dziubla, Thomas D.; Hilt, J. Zach; Bhattacharyya, Dibakar; Hennig, Bernhard

    2014-01-01

    Environmental pollution is increasing worldwide, and there is evidence that exposure to halogenated persistent organic pollutants (POPs) such as polychlorinated biphenyls can contribute to the pathology of inflammatory diseases such as atherosclerosis, diabetes, and cancer. Pollutant removal from contaminated sites and subsequent pollutant degradation are critical for reducing the long-term health risks associated with exposure. However, complete remediation of a toxicant from the environment is very difficult and cost-prohibitive. Furthermore, remediation technologies often result in the generation of secondary toxicants. Considering these circumstances, environmentally-friendly and sustainable remediation technologies and biomedical solutions to reduce vulnerability to environmental chemical insults need to be explored to reduce the overall health risks associate with exposure to environmental pollutants. We propose that positive lifestyle changes such as healthful nutrition and consumption of diets rich in fruits and vegetables or bioactive nutrients with antioxidant and/or anti-inflammatory properties will reduce the body’s vulnerability to environmental stressors and thus reduce toxicant-mediated disease pathologies. Interestingly, emerging evidence now implicates the incorporation of bioactive nutrients, such as plant-derived polyphenols, in technologies focused on the capture, sensing and remediation of halogenated POPs. We propose that human nutritional intervention in concert with the use of natural polyphenol sensing and remediation platforms may provide a sensible means to develop primary and long-term prevention strategies of diseases associated with many environmental toxic insults including halogenated POPs. PMID:24530186

  14. THE DETERMINATION OF TOTAL ORGANIC HALIDE IN WATER: A COMPARATIVE STUDY OF TWO INSTRUMENTS

    EPA Science Inventory

    Total organic halide (TOX) analyzers are commonly used to measure the amount of dissolved halogenated organic byproducts in disinfected waters. ecause of the lack of information on the identity of disinfection byproducts, rigorous testing of the dissolved organic halide (DOX) pro...

  15. Reactivity of some halogenated alkanes of 13X molecular sieve

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fevrier, D.; Vernet, J.L.; Mignon, P.

    1977-12-01

    The decomposition and transhalogenation products of trichlorofluoromethane (F 11), dichlorodifluoromethane (F-12), dichlorofluoromethane (F-21), chlorodifluoromethane (F-22), trichlorotrifluoroethane (F-113), and bromotrifluoromethane (F-13B1) in air on 13X molecular sieve at 150/sup o/ and 320/sup o/C were analyzed. All compounds decomposed to some extent except F-13B1 and F-113 at 150/sup o/C. The decomposition product was carbon dioxide except from F-21 and F-22, which decomposed more readily than the other Freons because of their hydrogen atoms and which yielded carbon monoxide. The sieves were not regenerated by sweeping with water in nitrogen, although adsorbed halogens were displaced and formed strong acids. Halogenated hydracids formed alongmore » with carbon dioxide by reaction with constitutional water of the sieves are probably responsible for the destruction of the sieve. Diagram, graphs, tables, and 17 references.« less

  16. Organic chemical aging mechanisms: An annotated bibliography. Waste Tank Safety Program

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Samuels, W.D.; Camaioni, D.M.; Nelson, D.A.

    1993-09-01

    An annotated bibliography has been compiled of the potential chemical and radiological aging mechanisms of the organic constituents (non-ferrocyanide) that would likely be found in the UST at Hanford. The majority of the work that has been conducted on the aging of organic chemicals used for extraction and processing of nuclear materials has been in conjunction with the acid or PUREX type processes. At Hanford the waste being stored in the UST has been stabilized with caustic. The aging factors that were used in this work were radiolysis, hydrolysis and nitrite/nitrate oxidation. The purpose of this work was two-fold: tomore » determine whether or not research had been or is currently being conducted on the species associated with the Hanford UST waste, either as a mixture or as individual chemicals or chemical functionalities, and to determine what areas of chemical aging need to be addressed by further research.« less

  17. Micropollutants and chemical residues in organic and conventional meat.

    PubMed

    Dervilly-Pinel, Gaud; Guérin, Thierry; Minvielle, Brice; Travel, Angélique; Normand, Jérôme; Bourin, Marie; Royer, Eric; Dubreil, Estelle; Mompelat, Sophie; Hommet, Frédéric; Nicolas, Marina; Hort, Vincent; Inthavong, Chanthadary; Saint-Hilaire, Mailie; Chafey, Claude; Parinet, Julien; Cariou, Ronan; Marchand, Philippe; Le Bizec, Bruno; Verdon, Eric; Engel, Erwan

    2017-10-01

    The chemical contamination levels of both conventional and organic meats were assessed. The objective was to provide occurrence data in a context of chronic exposure. Environmental contaminants (17 polychlorinated dibenzodioxins/dibenzofurans, 18 polychlorinated biphenyls (PCBs), 3 hexabromocyclododecane (HBCD) isomers, 6 mycotoxins, 6 inorganic compounds) together with chemical residues arising from production inputs (75 antimicrobials, 10 coccidiostats and 121 pesticides) have been selected as relevant compounds. A dedicated sampling strategy, representative of the French production allowed quantification of a large sample set (n=266) including both conventional (n=139) and organic (n=127) raw meat from three animal species (bovine, porcine, poultry). While contamination levels below regulatory limits were measured in all the samples, significant differences were observed between both species and types of farming. Several environmental contaminants (Dioxins, PCBs, HBCD, Zn, Cu, Cd, Pb, As) were measured at significantly higher levels in organic samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    PubMed

    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.

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

    PubMed

    Bani-Yaseen, Abdulilah Dawoud

    2016-08-21

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

  20. Ab Initio Studies of Halogen and Nitrogen Oxide Species of Interest in Stratospheric Chemistry

    NASA Technical Reports Server (NTRS)

    Lee, Timothy J.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    The ability of modern state-of-the art ab initio quantum chemical techniques to characterize reliably the gas-phase molecular structure, vibrational spectrum, electronic spectrum, and thermal stability of fluorine, chlorine, bromine and nitrogen oxide species will be demonstrated by presentation of some example studies. The ab initio results are shown to be in excellent agreement with the available experimental data, and where the experimental data are either not known or are inconclusive, the theoretical results are shown to fill in the gaps and to resolve experimental controversies. In addition, ab initio studies in which the electronic spectra and the characterization of excited electronic states of halogen oxide species will also be presented. Again where available, the ab initio results are compared to experimental observations, and are used to aid in the interpretation of experimental studies.