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Sample records for halogen absorbing means

  1. Absorbing boundaries in the mean-field approximation

    SciTech Connect

    Jhala, Chirag; Dreissigacker, Ingo; Lein, Manfred

    2010-12-15

    Absorbing boundaries in the mean-field approximation are investigated and applied to small systems interacting with strong laser fields. Two types of calculations are considered: (i) a variational approach with a complex absorbing potential included in the full Hamiltonian and (ii) the inclusion of a complex absorbing potential in the single-particle equations. It is elucidated that the second approach outperforms the variational approach for small grids.

  2. Sense or no-sense of the sum parameter for water soluble "adsorbable organic halogens" (AOX) and "absorbed organic halogens" (AOX-S18) for the assessment of organohalogens in sludges and sediments.

    PubMed

    Müller, German

    2003-07-01

    mineralogenic components derived from the erosion of fine grained sediments or soils. Assuming 50% geogenic particles with a mean Cl concentration of 103 mg/kg (as in shales and clays) the mineralogenic Cl-content could add about 50 mg/kg to the organic AOX in sewage sludge. The occurrence of insoluble and non-adsorbable PVC in sewage sludge exhibits the same problems as the mineralogenic constituents: a detection as AOX-S18 is possible when the final high temperature analytical step is applied. Plants as major sources of organohalogens have never been doubted. Only recently [Science 295 (2002) 985] based on the determination of the form of Cl with near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy and extended X-ray adsorption showed the variations in the inorganic Cl(-) and organo-Cl compounds with increasing humification of plant leaves from "fresh leaves--senescent leaves on plants--senescent leaves on soil--powdered top soil--isolated soil humus". His finding of exclusively inorganic Cl(-) in the starting material (fresh leaves) is controverse to our earlier results indicating the presence of ionic inorganic Cl together with water insoluble absorbed organohalogens (AOX-S18) in eight different macrophytes of both terrestrial and marine environments. Our research on AOX in interstitial water of anaerobic limnic sediments has led to the role of bromine playing in the diagenesis of the organic matter of sediments. In sediments of Lake Constance Br(-) concentrations in lake water at the sediment water interface increased from <0.01 to 0.25 mg/l in the pore water at 77 cm sediment depth. In the Neckar River a Br concentrations of 0.02 mg/l at the water/sediment interface increasing to 0.74 mg/l in pore water in 85 cm depth was found. Here a parallel development could be found with ammonium concentration and alkalinity. The very high positive correlation ammonium:bromide and bromide:alkalinity leads to the conclusion, that bromine, originally a high molecular

  3. Destruction of halogen-containing pesticides by means of detonation combustion.

    PubMed

    Biegańska, Jolanta

    2013-02-01

    Pesticides that contain a halogen functional group have been destructed by means of detonative combustion. The following compounds were examined: (1) atrazine-2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine-herbicide; (2) bromophos-O,4-bromo-2,5-dichlorophenyl O,O-dimethyl phosphorothioate-insecticide; (3) chloridazon-5-amino-4-chloro-2-phenylopyridazin-3(2H)-one-herbicide; (4) linuron-3-(3,4-dichlorophenyl)-1-metoxy-1-methylurea-herbicide; (5) metoxychlor-1,1,1-trichloro-2,2-bis(4-metoxyphenyl)ethane-insecticide and acaricide; and (6) trichlorfon-dimethyl 2,2,2-trichloro-1-hydroxyethylphosphonate-insecticide. Explosive material has been produced on the basis of ammonium nitrate, which served as an oxidizer while the pesticides were used as fuels. Composition of the explosive was adjusted in such a way as to respect thermodynamic parameters. Detonative decomposition of the mixtures has been carried out in shot-holes pre-drilled in soil. Efficiency of the pesticide decomposition has been examined with gas chromatography in order to determine pesticides residues in the environment. It was found that for some, the amount of pesticides in some compounds in the analyzed samples after decomposition was below the determination threshold of the applied method. PMID:23128990

  4. 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

  5. Pain and Mean Absorbed Dose to the Pubic Bone After Radiotherapy Among Gynecological Cancer Survivors

    SciTech Connect

    Waldenstroem, Ann-Charlotte; Olsson, Caroline; Wilderaeng, Ulrica; Dunberger, Gail; Lind, Helena; Al-Abany, Massoud; Palm, Asa; Avall-Lundqvist, Elisabeth; Johansson, Karl-Axel; Steineck, Gunnar

    2011-07-15

    Purpose: To analyze the relationship between mean absorbed dose to the pubic bone after pelvic radiotherapy for gynecological cancer and occurrence of pubic bone pain among long-term survivors. Methods and Materials: In an unselected, population-based study, we identified 823 long-term gynecological cancer survivors treated with pelvic radiotherapy during 1991-2003. For comparison, we used a non-radiation-treated control population of 478 matched women from the Swedish Population Register. Pain, intensity of pain, and functional impairment due to pain in the pubic bone were assessed with a study-specific postal questionnaire. Results: We analyzed data from 650 survivors (participation rate 79%) with median follow-up of 6.3 years (range, 2.3-15.0 years) along with 344 control women (participation rate, 72 %). Ten percent of the survivors were treated with radiotherapy; ninety percent with surgery plus radiotherapy. Brachytherapy was added in 81%. Complete treatment records were recovered for 538/650 survivors, with dose distribution data including dose-volume histograms over the pubic bone. Pubic bone pain was reported by 73 survivors (11%); 59/517 (11%) had been exposed to mean absorbed external beam doses <52.5 Gy to the pubic bone and 5/12 (42%) to mean absorbed external beam doses {>=}52.5 Gy. Thirty-three survivors reported pain affecting sleep, a 13-fold increased prevalence compared with control women. Forty-nine survivors reported functional impairment measured as pain walking indoors, a 10-fold increased prevalence. Conclusions: Mean absorbed external beam dose above 52.5 Gy to the pubic bone increases the occurrence of pain in the pubic bone and may affect daily life of long-term survivors treated with radiotherapy for gynecological cancer.

  6. 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.

  7. 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.

  8. [Source emission characteristics and impact factors of volatile halogenated organic compounds from wastewater treatment plant].

    PubMed

    He, Jie; Wang, Bo-Guang; Liu, Shu-Le; Zhao, De-Jun; Tang, Xiao-Dong; Zou, Yu

    2011-12-01

    A low enrichment method of using Tenax as absorbent and liquid nitrogen as refrigerant has been established to sample the volatile halogenated organic compounds in Guangzhou Liede municipal wastewater treatment plant as well as its ambient air. The composition and concentration of target halogenated hydrocarbons were analyzed by combined thermal desorption/GC-MS to explore its sources profile and impact factors. The result showed that 19 halogenated organic compounds were detected, including 11 halogenated alkanets, 3 halogenated alkenes, 3 halogenated aromatic hydrocarbons and 2 haloesters, with their total concentrations ranged from 34.91 microg x m(-3) to 127.74 microg x m(-3) and mean concentrations ranged from n.d. to 33.39 microg x m(-3). Main pollutants of the studied plant were CH2Cl2, CHCl3, CFC-12, C2H4Cl2, CFC-11, C2HCl3 and C2Cl4, they came from the wastewater by volatilization. Among the six processing units, the dehydration room showed the highest level of halogenated organic compounds, followed by pumping station, while the sludge thickener was the lowest. The emissions from pumping station, aeration tank and biochemical pool were significantly affected by temperature and humidity of environment. PMID:22468521

  9. Doppler-width thermodynamic thermometry by means of line-absorbance analysis

    SciTech Connect

    Castrillo, A.; De Vizia, M. D.; Gianfrani, L.; Moretti, L.; Galzerano, G.; Laporta, P.; Merlone, A.

    2011-09-15

    A clean and effective implementation of Doppler-width thermometry is described. Exploiting the relationship between line-center absorbance and integrated absorbance, the Doppler width of a molecular spectral line can be retrieved from a set of profiles resulting from different gas pressures. The method is validated by its application to numerically simulated spectra. Preliminary experiments, in water vapor samples, turn out to be successful, demonstrating Doppler-widths' retrieval in the near-infrared with a precision of 8x10{sup -5}, at the water triple point temperature. The direct link to the Boltzmann constant makes the proposed method very attractive for temperature metrology as a tool for the realization of a new thermodynamic temperature scale.

  10. CHARACTERIZATION OF AN ADVANCED GADOLINIUM NEUTRON ABSORBER ALLOY BY MEANS OF NEUTRON TRANSMISSION

    SciTech Connect

    Gregg W. Wachs

    2007-09-01

    Neutron transmission experiments were performed on samples of an advanced nickel-chromium-molybdenum-gadolinium (Ni-Cr-Mo-Gd) neutron absorber alloy. The primary purpose of the experiments was to demonstrate the thermal neutron absorbing capability of the alloy at specific gadolinium dopant levels. The new alloy is to be deployed for criticality control of highly enriched DOE SNF. For the transmission experiments, alloy test samples were fabricated with 0.0, 1.58 and 2.1 wt% natural gadolinium dispersed in a Ni-Cr-Mo base alloy. The transmission experiments were successfully carried out at the Los Alamos Neutron Science Center (LANSCE). Measured data from the neutron transmission experiments were compared to calculated results derived from a simple exponential transmission formula using only radiative capture cross sections. Excellent agreement between the measured and calculated results demonstrated the expected strong thermal absorption capability of the gadolinium poison and in addition, verified the measured elemental composition of the alloy test samples. The good agreement also indirectly confirmed that the gadolinium was dispersed fairly uniformly in the alloy and the ENDF VII radiative capture cross section data were accurate.

  11. Metal Halogen Battery Construction with Combustion Arrester to Prevent Self Propagation of Hydrogen-Halogen Reactions

    SciTech Connect

    Hammond, M. J.; Kilic, S.

    1983-12-27

    A metal halogen battery construction containing a special reactor means having a combustion arrester device and a reaction initiator device, whereby the reactor means permits controlled recombination of hydrogen gas and halogen gas in the system to form hydrogen halide, which is then dispersed into the store means of the battery.

  12. Mean apical concentration and duration in the comparative bioavailability of slowly absorbed and eliminated drug preparations.

    PubMed

    Pollak, P T; Freeman, D J; Carruthers, S G

    1988-06-01

    Present criteria for comparing bioavailability are inadequate when the Cmax and tmax cannot be reliably identified in individual subjects. Drug formulations which are slowly absorbed and eliminated have concentration-time profiles with a broad apex, increasing the likelihood that samples taken at the apical region of the curve will have statistically indistinguishable concentrations. Using data from a study of three dosage forms of piroxicam, we propose an alternative approach which decreases the influence of sampling bias and analytical error on the identification of the apex of the concentration-time curve and provides a simple tool for describing the shape of the curve around the apex. An adequate frequency of sampling around the expected apex of the concentration-time curve and consideration of the coefficient of variation (CV) of the analytical assay when assessing the observed Cmax are used in defining new parameters. This approach may be useful for studying the relationship of onset and duration of maximal plasma concentration to the efficacy and toxicity of drugs and in developing standards for comparing the bioavailability of slow-release preparations, which is of increasing interest to pharmaceutical companies and regulatory agencies. PMID:3171924

  13. Mean Absorbed Dose to the Anal-Sphincter Region and Fecal Leakage among Irradiated Prostate Cancer Survivors

    SciTech Connect

    Alsadius, David; Hedelin, Maria; Lundstedt, Dan; Pettersson, Niclas; Wilderaeng, Ulrica; Steineck, Gunnar

    2012-10-01

    Purpose: To supplement previous findings that the absorbed dose of ionizing radiation to the anal sphincter or lower rectum affects the occurrence of fecal leakage among irradiated prostate-cancer survivors. We also wanted to determine whether anatomically defining the anal-sphincter region as the organ at risk could increase the degree of evidence underlying clinical guidelines for restriction doses to eliminate this excess risk. Methods and Materials: We identified 985 men irradiated for prostate cancer between 1993 and 2006. In 2008, we assessed long-term gastrointestinal symptoms among these men using a study-specific questionnaire. We restrict the analysis to the 414 men who had been treated with external beam radiation therapy only (no brachytherapy) to a total dose of 70 Gy in 2-Gy daily fractions to the prostate or postoperative prostatic region. On reconstructed original radiation therapy dose plans, we delineated the anal-sphincter region as an organ at risk. Results: We found that the prevalence of long-term fecal leakage at least once per month was strongly correlated with the mean dose to the anal-sphincter region. Examining different dose intervals, we found a large increase at 40 Gy; {>=}40 Gy compared with <40 Gy gave a prevalence ratio of 3.8 (95% confidence interval 1.6-8.6). Conclusions: This long-term study shows that mean absorbed dose to the anal-sphincter region is associated with the occurrence of long-term fecal leakage among irradiated prostate-cancer survivors; delineating the anal-sphincter region separately from the rectum and applying a restriction of a mean dose <40 Gy will, according to our data, reduce the risk considerably.

  14. 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.

  15. 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.

  16. Volatile halogenated hydrocarbons in foods

    SciTech Connect

    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.

  17. 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

  18. The Halogen Bond.

    PubMed

    Cavallo, Gabriella; Metrangolo, Pierangelo; Milani, Roberto; Pilati, Tullio; Priimagi, Arri; Resnati, Giuseppe; Terraneo, Giancarlo

    2016-02-24

    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

  19. Metal halogen electrochemical cell

    DOEpatents

    Bellows, Richard J.; Kantner, Edward

    1988-08-23

    It has now been discovered that reduction in the coulombic efficiency of metal halogen cells can be minimized if the microporous separator employed in such cells is selected from one which is preferably wet by the aqueous electrolyte and is not wet substantially by the cathodic halogen.

  20. Halogen bonding anion recognition.

    PubMed

    Brown, Asha; Beer, Paul D

    2016-07-01

    A halogen bond is an attractive non-covalent interaction between an electrophilic region in a covalently bonded halogen atom and a Lewis base. While these interactions have long been exploited as a tool in crystal engineering their powerful ability to direct supramolecular self-assembly and molecular recognition processes in solution has, until recently, been overlooked. During the last decade however an ever-increasing number of studies on solution-phase halogen-bond-mediated anion recognition processes has emerged. This Feature Article summarises advancements which have been made thus far in this rapidly developing research area. We survey the use of iodoperfluoroarene, haloimidazolium and halotriazole/triazolium halogen-bond-donor motifs in anion receptor design, before providing an account of our research into the application of mechanically interlocked rotaxane and catenane frameworks as halogen bonding anion host systems. PMID:27273600

  1. Relative Importance of Hip and Sacral Pain Among Long-Term Gynecological Cancer Survivors Treated With Pelvic Radiotherapy and Their Relationships to Mean Absorbed Doses

    SciTech Connect

    Waldenstroem, Ann-Charlotte; Olsson, Caroline; Wilderaeng, Ulrica; Dunberger, Gail; Lind, Helena; Alevronta, Eleftheria; Al-Abany, Massoud; Tucker, Susan; Avall-Lundqvist, Elisabeth; Johansson, Karl-Axel; Steineck, Gunnar

    2012-10-01

    Purpose: To investigate the relative importance of patient-reported hip and sacral pain after pelvic radiotherapy (RT) for gynecological cancer and its relationship to the absorbed doses in these organs. Methods and Materials: We used data from a population-based study that included 650 long-term gynecological cancer survivors treated with pelvic RT in the Gothenburg and Stockholm areas in Sweden with a median follow-up of 6 years (range, 2-15) and 344 population controls. Symptoms were assessed through a study-specific postal questionnaire. We also analyzed the hip and sacral dose-volume histogram data for 358 of the survivors. Results: Of the survivors, one in three reported having or having had hip pain after completing RT. Daily pain when walking was four times as common among the survivors compared to controls. Symptoms increased in frequency with a mean absorbed dose >37.5 Gy. Also, two in five survivors reported pain in the sacrum. Sacral pain also affected their walking ability and tended to increase with a mean absorbed dose >42.5 Gy. Conclusions: Long-term survivors of gynecological cancer treated with pelvic RT experience hip and sacral pain when walking. The mean absorbed dose was significantly related to hip pain and was borderline significantly related to sacral pain. Keeping the total mean absorbed hip dose below 37.5 Gy during treatment might lower the occurrence of long-lasting pain. In relation to the controls, the survivors had a lower occurrence of pain and pain-related symptoms from the hips and sacrum compared with what has previously been reported for the pubic bone.

  2. 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.

  3. Halogens in the atmosphere

    NASA Technical Reports Server (NTRS)

    Cicerone, R. J.

    1981-01-01

    Atmospheric halogen measurement data are presented for: (1) inorganic and organic gaseous compounds of chlorine, fluorine, bromine and iodine; and (2) chloride, fluoride, bromide and iodine in particulate form and in precipitation. The roles that these data and other, unavailable data play in the determination of the global cycles of the halogens are discussed. It is found that the speciation of the halogen gases in the troposphere is uncertain, with the only inorganic species detected by species-specific methods being HC1 and SF6. It is shown that heterogeneous reactions, both gas-to-particle and particle-to-gas processes, precipitation removal, and sea-salt aerosol generation and fractionation processes, need quantitative investigation to allow progress in estimating halogen sources and sinks. Where practical, quantitative comparisons are made between measured and predicted concentrations.

  4. Occurrence of halogenated alkaloids.

    PubMed

    Gribble, Gordon W

    2012-01-01

    Once considered to be isolation artifacts or chemical "mistakes" of nature, the number of naturally occurring organohalogen compounds has grown from a dozen in 1954 to >5000 today. Of these, at least 25% are halogenated alkaloids. This is not surprising since nitrogen-containing pyrroles, indoles, carbolines, tryptamines, tyrosines, and tyramines are excellent platforms for biohalogenation, particularly in the marine environment where both chloride and bromide are plentiful for biooxidation and subsequent incorporation into these electron-rich substrates. This review presents the occurrence of all halogenated alkaloids, with the exception of marine bromotyrosines where coverage begins where it left off in volume 61 of The Alkaloids. Whereas the biological activity of these extraordinary compounds is briefly cited for some examples, a future volume of The Alkaloids will present full coverage of this topic and will also include selected syntheses of halogenated alkaloids. Natural organohalogens of all types, especially marine and terrestrial halogenated alkaloids, comprise a rapidly expanding class of natural products, in many cases expressing powerful biological activity. This enormous proliferation has several origins: (1) a revitalization of natural product research in a search for new drugs, (2) improved compound characterization methods (multidimensional NMR, high-resolution mass spectrometry), (3) specific enzyme-based and other biological assays, (4) sophisticated collection methods (SCUBA and remote submersibles for deep ocean marine collections), (5) new separation and purification techniques (HPLC and countercurrent separation), (6) a greater appreciation of traditional folk medicine and ethobotany, and (7) marine bacteria and fungi as novel sources of natural products. Halogenated alkaloids are truly omnipresent in the environment. Indeed, one compound, Q1 (234), is ubiquitous in the marine food web and is found in the Inuit from their diet of whale

  5. Sources of Halogen Oxides Along the Coastline of New Zealand: A Field Measurement Study

    NASA Astrophysics Data System (ADS)

    Martínez-Avilés, Mónica; Kreher, Karin; Johnston, Paul; Thomas, Alan; Hay, Tim; Schofield, Robyn; Kenntner, Mareike

    2010-05-01

    The 2006 WMO/UNEP Scientific Assessment of Ozone Depletion identified halogenated very short-lived substances (VSLS) as contributors to the atmospheric budget of halogens. As well, it raised a question regarding the extent of the contribution of halogenated VSLS to atmospheric Bry and Iy. Traditionally, scientists have been more concerned in determining the anthropogenic budget of halogenated compounds while nature is the major producer of such species. In order to have a complete atmospheric budget of halogenated VSLS, it is important to have a better understanding of what species are biogenically produced as well as their respective degradation pathways. Oceanic emissions of halocarbons may be a new link between climate change and the composition of the global atmosphere. The rates of halocarbon emissions are sensitive to sea-surface temperatures (SSTs), nutrient supply and upwelling; all of which are to be affected by climate change. Therefore, increases in SSTs will increase emission rates. On the one hand, seaweed has been identified as a major producer of biogenic polyhalogenated VSLS. Marine macroalgae (kelp) and phytoplankton emit halogen containing gases into the marine boundary layer, constituting 90 to 95% of the total global flux of volatile halocarbons to the atmosphere. On the other hand, the possibility of industrial scale marine kelp farming as a means of carbon sequestration (i.e. marine analogy of the Kyoto Protocol forest) is being pondered by countries with long coastlines and little land suitable for forestation. Would a Kyoto Protocol forest analog be the right strategy for climate change mitigation? With the use of a portable Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) spectrometer, studies have been performed in the coast of New Zealand in order to determine the presence of BrO and IO during the spring and summer months of the Southern Hemisphere. MAX-DOAS uses scattered sunlight received from multiple viewing

  6. 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.

  7. 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.

  8. Biogeochemistry of Halogenated Hydrocarbons

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

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

  9. Cytotoxicity of halogenated graphenes

    NASA Astrophysics Data System (ADS)

    Teo, Wei Zhe; Khim Chng, Elaine Lay; Sofer, Zdeněk; Pumera, Martin

    2013-12-01

    Graphene and its family of derivatives possess unique and remarkable physicochemical properties which make them valuable materials for applications in many areas like electronics, energy storage and biomedicine. In response to the possibility of its large-scale manufacturing as commercial products in the future, an investigation was conducted to determine the cytotoxicity of one particular family of graphene derivatives, the halogenated graphenes, for the first time. Halogenated graphenes were prepared through thermal exfoliation of graphite oxide in gaseous chlorine, bromine or iodine atmospheres to yield chlorine- (TRGO-Cl), bromine- (TRGO-Br) and iodine-doped graphene (TRGO-I) respectively. 24 h exposure of human lung carcinoma epithelial cells (A549) to the three halogenated graphenes and subsequent cell viability assessments using methylthiazolyldiphenyl-tetrazolium bromide (MTT) and water-soluble tetrazolium salt (WST-8) assays revealed that all the halogenated graphenes examined are rather cytotoxic at the concentrations tested (3.125 μg mL-1 to 200 μg mL-1) and the effects are dose-dependent, with TRGO-Cl reducing the cell viability to as low as 25.7% at the maximum concentration of 200 μg mL-1. Their levels of cytotoxicity can be arranged in the order of TRGO-Cl > TRGO-Br > TRGO-I, and it is suggested that the amount of halogen present in the graphene material is the determining factor for the observed trend. Control experiments were carried out to test for possible nanomaterial-induced interference as a consequence of reaction between the halogenated graphenes and the viability markers (MTT/WST-8 reagent) or binding of the formazan products under cell-free conditions. The data obtained eliminate the probability of significant influence by these interferents as the change in the normalized percentage of formazan formed is relatively small and thorough washings were performed prior to the viability assessments to reduce the amount of halogenated

  10. CATALYTIC DEHYDROHALOGENATION: A CHEMICAL DESTRUCTION METHOD FOR HALOGENATED ORGANICS

    EPA Science Inventory

    Dehydrohalogenation shows potential as a means for converting certain halogenated organics in wastes to inorganic salts and gaseous aliphatic compounds. Dehydrohalogenation is a dehalogenation/elimination reaction that is initiated by a strong base. The resulting products are the...

  11. Halogens in CM Chondrites

    NASA Astrophysics Data System (ADS)

    Menard, J. M.; Caron, B.; Jambon, A.; Michel, A.; Villemant, B.

    2013-09-01

    We set up an extraction line of halogens (fluorine, chlorine) by pyrohydrolysis with 50 mg of rock. We analyzed 7 CM2 chondrites found in Antarctica and found that the Cl content of meteorites with an intact fusion crust is higher than those without.

  12. Asymmetric bifurcated halogen bonds.

    PubMed

    Novák, Martin; Foroutan-Nejad, Cina; Marek, Radek

    2015-03-01

    Halogen bonding (XB) is being extensively explored for its potential use in advanced materials and drug design. Despite significant progress in describing this interaction by theoretical and experimental methods, the chemical nature remains somewhat elusive, and it seems to vary with the selected system. In this work we present a detailed DFT analysis of three-center asymmetric halogen bond (XB) formed between dihalogen molecules and variously 4-substituted 1,2-dimethoxybenzene. The energy decomposition, orbital, and electron density analyses suggest that the contribution of electrostatic stabilization is comparable with that of non-electrostatic factors. Both terms increase parallel with increasing negative charge of the electron donor molecule in our model systems. Depending on the orientation of the dihalogen molecules, this bifurcated interaction may be classified as 'σ-hole - lone pair' or 'σ-hole - π' halogen bonds. Arrangement of the XB investigated here deviates significantly from a recent IUPAC definition of XB and, in analogy to the hydrogen bonding, the term bifurcated halogen bond (BXB) seems to be appropriate for this type of interaction. PMID:25656525

  13. Type II halogen···halogen contacts are halogen bonds.

    PubMed

    Metrangolo, Pierangelo; Resnati, Giuseppe

    2014-01-01

    Cl/Br/I alternative substitutions in a series of dihalophenols indicate that type I and type II halogen···halogen contacts have different chemical nature. Only the latter ones qualify as true halogen bonds, according to the recent IUPAC definition. PMID:25075314

  14. Biological dehalogenation and halogenation reactions.

    PubMed

    van Pée, Karl Heinz; Unversucht, Susanne

    2003-07-01

    A large number of halogenated compounds is produced by chemical synthesis. Some of these compounds are very toxic and cause enormous problems to human health and to the environment. Investigations on the degradation of halocompounds by microorganisms have led to the detection of various dehalogenating enzymes catalyzing the removal of halogen atoms under aerobic and anaerobic conditions involving different mechanisms. On the other hand, more than 3500 halocompounds are known to be produced biologically, some of them in great amounts. Until 1997, only haloperoxidases were thought to be responsible for incorporation of halogen atoms into organic compounds. However, recent investigations into the biosynthesis of halogenated metabolites by bacteria have shown that a novel type of halogenating enzymes, FADH(2)-dependent halogenases, are involved in biosyntheses of halogenated metabolites. In every gene cluster coding for the biosynthesis of a halogenated metabolite, isolated so far, one or several genes for FADH(2)-dependent halogenases have been identified. PMID:12738254

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

    USGS Publications Warehouse

    de Paiva, Azevedo, L.H.; 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.

  17. Meaning

    NASA Astrophysics Data System (ADS)

    Harteveld, Casper

    The second world to be considered concerns Meaning. In contrast to Reality and Play, this world relates to the people, disciplines, and domains that are focused on creating a certain value. For example, if this value is about providing students knowledge about physics, it involves teachers, the learning sciences, and the domains education and physics. This level goes into the aspects and criteria that designers need to take into account from this perspective. The first aspect seems obvious when we talk of “games with a serious purpose.” They have a purpose and this needs to be elaborated on, for example in terms of what “learning objectives” it attempts to achieve. The subsequent aspect is not about what is being pursued but how. To attain a value, designers have to think about a strategy that they employ. In my case this concerned looking at the learning paradigms that have come into existence in the past century and see what they have to tell us about learning. This way, their principles can be translated into a game environment. This translation involves making the strategy concrete. Or, in other words, operationalizing the plan. This is the third aspect. In this level, I will further specifically explain how I derived requirements from each of the learning paradigms, like reflection and exploration, and how they can possibly be related to games. The fourth and final aspect is the context in which the game is going to be used. It matters who uses the game and when, where, and how the game is going to be used. When designers have looked at these aspects, they have developed a “value proposal” and the worth of it may be judged by criteria, like motivation, relevance, and transfer. But before I get to this, I first go into how we human beings are meaning creators and what role assumptions, knowledge, and ambiguity have in this. I will illustrate this with some silly jokes about doctors and Mickey Mouse, and with an illusion.

  18. 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.

  19. 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.

  20. Modern halogen leak detectors /Review/

    NASA Astrophysics Data System (ADS)

    Evlampiev, A. I.; Karpov, V. I.; Levina, L. E.

    1981-04-01

    The halogen method is one of the basic techniques of leak detection for monitoring airtightness in such objects as refrigeration equipment and aerosol containers. Sensitivity has been improved by heated platinum emitters which stabilize background currents. Methods for protecting the region in which the gas is selected include placing the sensitive element in a new flow gauge and keeping the chamber at a certain distance from the tested surface. Chromatograph separating columns both increase sensitivity and distinguish test materials on a background of extraneous halogen-containing materials. Solid-state platinum diodes have been used as the sensitive elements of halogen leak detectors. Leak detectors based on electron-capture practically eliminate the effect of contamination of the surrounding atmosphere on leak detector sensitivity. A technique of vacuum testing is based on the high affinity of halogen-containing materials for electrons.

  1. Modern halogen leak detectors /Review/

    NASA Astrophysics Data System (ADS)

    Evlampiev, A. I.; Karpov, V. I.; Levina, L. E.

    1980-09-01

    The halogen method is one of the basic techniques of leak detection for monitoring airtightness in such objects as refrigeration equipment and aerosol containers. Sensitivity has been improved by heated platinum emitters which stabilize background currents. Methods for protecting the region in which the gas is selected include placing the sensitive element in a new flow gauge and keeping the chamber at a certain distance from the tested surface. Chromatograph separating columns both increase sensitivity and distinguish test materials on a background of extraneous halogen-containing materials. Solid-state platinum diodes have been used as the sensitive elements of halogen leak detectors. Leak detectors based on electron-capture practically eliminate the effect of contamination of the surrounding atmosphere on leak detector sensitivity. A technique of vacuum testing is based on the high affinity of halogen-containing materials for electrons.

  2. 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.

  3. The Halogen Occultation Experiment

    NASA Technical Reports Server (NTRS)

    Russell, James M., III; Gordley, Larry L.; Park, Jae H.; Drayson, S. R.; Hesketh, W. D.; Cicerone, Ralph J.; Tuck, Adrian F.; Frederick, John E.; Harries, John E.; Crutzen, Paul J.

    1993-01-01

    The Halogen Occultation Experiment (HALOE) uses solar occultation to measure vertical profiles of O3, HCl, HF, CH4, H2O, NO, NO2, aerosol extinction, and temperature versus pressure with an instantaneous vertical field of view of 1.6 km at the earth limb. Latitudinal coverage is from 80 deg S to 80 deg N over the course of 1 year and includes extensive observations of the Antarctic region during spring. The altitude range of the measurements extends from about 15 km to about 60-130 km, depending on channel. Experiment operations have been essentially flawless, and all performance criteria either meet or exceed specifications. Internal data consistency checks, comparisons with correlative measurements, and qualitative comparisons with 1985 atmospheric trace molecule spectroscopy (ATMOS) results are in good agreement. Examples of pressure versus latitude cross sections and a global orthographic projection for the September 21 to October 15, 1992, period show the utility of CH4, HF, and H2O as tracers, the occurrence of dehydration in the Antarctic lower stratosphere, the presence of the water vapor hygropause in the tropics, evidence of Antarctic air in the tropics, the influence of Hadley tropical upwelling, and the first global distribution of HCl, HF, and NO throughout the stratosphere. Nitric oxide measurements extend through the lower thermosphere.

  4. Mercury and halogens in coal: Chapter 2

    USGS Publications Warehouse

    Kolker, Allan; Quick, Jeffrey C.

    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

  5. 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.

  6. 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. PMID:27060916

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

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... is subject to regulations in 40 CFR parts 264 through 266 that have required a determination of the... 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...

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... is subject to regulations in 40 CFR parts 264 through 266 that have required a determination of the... 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...

  9. 40 CFR 63.994 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... is subject to regulations in 40 CFR parts 264 through 266 that have required a determination of the... 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...

  10. 40 CFR 63.994 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... is subject to regulations in 40 CFR parts 264 through 266 that have required a determination of the... 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...

  11. 40 CFR 63.994 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... is subject to regulations in 40 CFR parts 264 through 266 that have required a determination of the... 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...

  12. ATMOSPHERIC FREONS AND HALOGENATED COMPOUNDS

    EPA Science Inventory

    Ambient levels of atmospheric Freons, halogenated hydrocarbons, and SF6 were measured at various locations in the U.S.A. Compounds such as CCl3F, CCl2F2, CH3-CCl3, and CCl4 were ubiquitious and generally measured at sub ppb levels. Tropospherically reactive compounds such as C2Cl...

  13. Sound Absorbers

    NASA Astrophysics Data System (ADS)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  14. Halogen bonds in biological molecules

    PubMed Central

    Auffinger, Pascal; Hays, Franklin A.; Westhof, Eric; Ho, P. Shing

    2004-01-01

    Short oxygen–halogen interactions have been known in organic chemistry since the 1950s and recently have been exploited in the design of supramolecular assemblies. The present survey of protein and nucleic acid structures reveals similar halogen bonds as potentially stabilizing inter- and intramolecular interactions that can affect ligand binding and molecular folding. A halogen bond in biomolecules can be defined as a short CX···OY interaction (CX is a carbon-bonded chlorine, bromine, or iodine, and OY is a carbonyl, hydroxyl, charged carboxylate, or phosphate group), where the X···O distance is less than or equal to the sums of the respective van der Waals radii (3.27 Å for Cl···O, 3.37Å for Br···O, and 3.50 Å for I···O) and can conform to the geometry seen in small molecules, with the CX···O angle ≈165° (consistent with a strong directional polarization of the halogen) and the X···OY angle ≈120°. Alternative geometries can be imposed by the more complex environment found in biomolecules, depending on which of the two types of donor systems are involved in the interaction: (i) the lone pair electrons of oxygen (and, to a lesser extent, nitrogen and sulfur) atoms or (ii) the delocalized π -electrons of peptide bonds or carboxylate or amide groups. Thus, the specific geometry and diversity of the interacting partners of halogen bonds offer new and versatile tools for the design of ligands as drugs and materials in nanotechnology. PMID:15557000

  15. Halogen bonds in biological molecules.

    PubMed

    Auffinger, Pascal; Hays, Franklin A; Westhof, Eric; Ho, P Shing

    2004-11-30

    Short oxygen-halogen interactions have been known in organic chemistry since the 1950s and recently have been exploited in the design of supramolecular assemblies. The present survey of protein and nucleic acid structures reveals similar halogen bonds as potentially stabilizing inter- and intramolecular interactions that can affect ligand binding and molecular folding. A halogen bond in biomolecules can be defined as a short C-X...O-Y interaction (C-X is a carbon-bonded chlorine, bromine, or iodine, and O-Y is a carbonyl, hydroxyl, charged carboxylate, or phosphate group), where the X...O distance is less than or equal to the sums of the respective van der Waals radii (3.27 A for Cl...O, 3.37 A for Br...O, and 3.50 A for I...O) and can conform to the geometry seen in small molecules, with the C-X...O angle approximately 165 degrees (consistent with a strong directional polarization of the halogen) and the X...O-Y angle approximately 120 degrees . Alternative geometries can be imposed by the more complex environment found in biomolecules, depending on which of the two types of donor systems are involved in the interaction: (i) the lone pair electrons of oxygen (and, to a lesser extent, nitrogen and sulfur) atoms or (ii) the delocalized pi -electrons of peptide bonds or carboxylate or amide groups. Thus, the specific geometry and diversity of the interacting partners of halogen bonds offer new and versatile tools for the design of ligands as drugs and materials in nanotechnology. PMID:15557000

  16. Structural Perspective on Enzymatic Halogenation

    PubMed Central

    2008-01-01

    Simple halogen substituents frequently afford key structural features that account for the potency and selectivity of natural products, including antibiotics and hormones. For example, when a single chlorine atom on the antibiotic vancomycin is replaced by hydrogen, the resulting antibacterial activity decreases by up to 70% (HarrisC. M.; KannanR.; KopeckaH.; HarrisT. M.J. Am. Chem. Soc.1985, 107, 6652−6658). This Account analyzes how structure underlies mechanism in halogenases, the molecular machines designed by nature to incorporate halogens into diverse substrates. Traditional synthetic methods of integrating halogens into complex molecules are often complicated by a lack of specificity and regioselectivity. Nature, however, has developed a variety of elegant mechanisms for halogenating specific substrates with both regio- and stereoselectivity. An improved understanding of the biological routes toward halogenation could lead to the development of novel synthetic methods for the creation of new compounds with enhanced functions. Already, researchers have co-opted a fluorinase from the microorganism Streptomyces cattleya to produce 18F-labeled molecules for use in positron emission tomography (PET) (DengH.; CobbS. L.; GeeA. D.; LockhartA.; MartarelloL.; McGlincheyR. P.; O’HaganD.; OnegaM.Chem. Commun.2006, 652−654). Therefore, the discovery and characterization of naturally occurring enzymatic halogenation mechanisms has become an active area of research. The catalogue of known halogenating enzymes has expanded from the familiar haloperoxidases to include oxygen-dependent enzymes and fluorinases. Recently, the discovery of a nucleophilic halogenase that catalyzes chlorinations has expanded the repertoire of biological halogenation chemistry (DongC.; HuangF.; DengH.; SchaffrathC.; SpencerJ. B.; O’HaganD.; NaismithJ. H.Nature2004, 427, 561−56514765200). Structural characterization has provided a basis toward a mechanistic understanding of the specificity

  17. 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

  18. 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.

  19. 40 CFR 721.505 - Halogenated acrylonitrile.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.505 Halogenated acrylonitrile. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as halogenated acrylonitrile, (PMN P-90-299)...

  20. 40 CFR 721.505 - Halogenated acrylonitrile.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.505 Halogenated acrylonitrile. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as halogenated acrylonitrile, (PMN P-90-299)...

  1. Halogen Chemistry on Catalytic Surfaces.

    PubMed

    Moser, Maximilian; Pérez-Ramírez, Javier

    2016-01-01

    Halogens are key building blocks for the manufacture of high-value products such as chemicals, plastics, and pharmaceuticals. The catalytic oxidation of HCl and HBr is an attractive route to recover chlorine and bromine in order to ensure the sustainability of the production processes. Very few materials withstand the high corrosiveness and the strong exothermicity of the reactions and among them RuO2 and CeO2-based catalysts have been successfully applied in HCl oxidation. The search for efficient systems for HBr oxidation was initiated by extrapolating the results of HCl oxidation based on the chemical similarity of these reactions. Interestingly, despite its inactivity in HCl oxidation, TiO2 was found to be an outstanding HBr oxidation catalyst, which highlighted that the latter reaction is more complex than previously assumed. Herein, we discuss the results of recent comparative studies of HCl and HBr oxidation on both rutile-type (RuO2, IrO2, and TiO2) and ceria-based catalysts using a combination of advanced experimental and theoretical methods to provide deeper molecular-level understanding of the reactions. This knowledge aids the design of the next-generation catalysts for halogen recycling. PMID:27131113

  2. Competition between hydrogen and halogen bonding in halogenated 1-methyluracil: Water systems.

    PubMed

    Hogan, Simon W L; van Mourik, Tanja

    2016-03-30

    The competition between hydrogen- and halogen-bonding interactions in complexes of 5-halogenated 1-methyluracil (XmU; X = F, Cl, Br, I, or At) with one or two water molecules in the binding region between C5-X and C4O4 is investigated with M06-2X/6-31+G(d). In the singly-hydrated systems, the water molecule forms a hydrogen bond with C4O4 for all halogens, whereas structures with a halogen bond between the water oxygen and C5-X exist only for X = Br, I, and At. Structures with two waters forming a bridge between C4O and C5-X (through hydrogen- and halogen-bonding interactions) exist for all halogens except F. The absence of a halogen-bonded structure in singly-hydrated ClmU is therefore attributed to the competing hydrogen-bonding interaction with C4O4. The halogen-bond angle in the doubly-hydrated structures (150-160°) is far from the expected linearity of halogen bonds, indicating that significantly non-linear halogen bonds may exist in complex environments with competing interactions. © 2016 Wiley Periodicals, Inc. PMID:26773851

  3. Halogen Bonding in Hypervalent Iodine Compounds.

    PubMed

    Catalano, Luca; Cavallo, Gabriella; Metrangolo, Pierangelo; Resnati, Giuseppe; Terraneo, Giancarlo

    2016-01-01

    Halogen bonds occur when electrophilic halogens (Lewis acids) attractively interact with donors of electron density (Lewis bases). This term is commonly used for interactions undertaken by monovalent halogen derivatives. The aim of this chapter is to show that the geometric features of the bonding pattern around iodine in its hypervalent derivatives justify the understanding of some of the longer bonds as halogen bonds. We suggest that interactions directionality in ionic and neutral λ(3)-iodane derivatives is evidence that the electron density distribution around iodine atoms is anisotropic, a region of most positive electrostatic potential exists on the extensions of the covalent bonds formed by iodine, and these positive caps affect, or even determine, the crystal packing of these derivatives. For instance, the short cation-anion contacts in ionic λ(3)-iodane and λ(5)-iodane derivatives fully match the halogen bond definition and geometrical prerequisites. The same holds for the short contacts the cation of ionic λ(3)-iodanes forms with lone-pair donors or the short contacts given by neutral λ(3)-iodanes with incoming nucleophiles. The longer and weaker bonds formed by iodine in hypervalent compounds are usually called secondary bondings and we propose that the term halogen bond can also be used. Compared to the term secondary bond, halogen bond may possibly be more descriptive of some bonding features, e.g., its directionality and the relationships between structure of interacting groups and interaction strength. PMID:26809623

  4. 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. PMID:25504313

  5. Does fluorine participate in halogen bonding?

    PubMed

    Eskandari, Kiamars; Lesani, Mina

    2015-03-16

    When R is sufficiently electron withdrawing, the fluorine in the R-F molecules could interact with electron donors (e.g., ammonia) and form a noncovalent bond (F⋅⋅⋅N). Although these interactions are usually categorized as halogen bonding, our studies show that there are fundamental differences between these interactions and halogen bonds. Although the anisotropic distribution of electronic charge around a halogen is responsible for halogen bond formations, the electronic charge around the fluorine in these molecules is spherical. According to source function analysis, F is the sink of electron density at the F⋅⋅⋅N BCP, whereas other halogens are the source. In contrast to halogen bonds, the F⋅⋅⋅N interactions cannot be regarded as lump-hole interactions; there is no hole in the valence shell charge concentration (VSCC) of fluorine. Although the quadruple moment of Cl and Br is mainly responsible for the existence of σ-holes, it is negligibly small in the fluorine. Here, the atomic dipole moment of F plays a stabilizing role in the formation of F⋅⋅⋅N bonds. Interacting quantum atoms (IQA) analysis indicates that the interaction between halogen and nitrogen in the halogen bonds is attractive, whereas it is repulsive in the F⋅⋅⋅N interactions. Virial-based atomic energies show that the fluorine, in contrast to Cl and Br, stabilize upon complex formation. According to these differences, it seems that the F⋅⋅⋅N interactions should be referred to as "fluorine bond" instead of halogen bond. PMID:25652256

  6. 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

    2015-08-01

    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. PMID:26151227

  7. Enzyme mimics: Halogen and chalcogen team up

    NASA Astrophysics Data System (ADS)

    Metrangolo, Pierangelo; Resnati, Giuseppe

    2012-06-01

    The behaviour of di-selenol enzyme mimics indicates that a halogen bond between selenium and iodine, and a chalcogen interaction between the two selenium atoms, play an important role in the activation of thyroid hormones.

  8. Efficiency of light-emitting diode and halogen units in reducing residual monomers

    PubMed Central

    de Assis Ribeiro Carvalho, Felipe; Almeida, Rhita C.; Almeida, Marco Antonio; Cevidanes, Lucia H. S.; Leite, Marcia C. Amorim M.

    2011-01-01

    Introduction In this in-vitro study, we aimed to compare the residual monomers in composites beneath brackets bonded to enamel, using a light-emitting diode (LED) or a halogen unit, and to compare the residual monomers in the central to the peripheral areas of the composite. Methods Twenty bovine teeth preserved in 0.1% thymol were used in this study. Ten teeth were used to standardize the thickness of the composite film, since different thicknesses would cause different absorbance of light. Brackets were bonded to 10 bovine incisors, with the halogen light (n = 5) and the LED (n = 5). The brackets were debonded, and the remaining composite on the enamel surface was sectioned in 2 regions: peripheral (0.8 mm) and central, resulting in 2 subgroups per group: central halogen (n = 5), peripheral halogen (n = 5), central LED (n = 5), and peripheral LED (n = 5). The spectrometric analysis in the infrared region was used to measure the free monomers with the attenuated total reflectance method. Results Normal distribution was tested by using the Kolmogorov-Smirnov test. Data were compared by 2-way analysis of variance (ANOVA) at P <0.05. The LED group showed fewer residual monomers than did the halogen group (P = 0.014). No differences were found among the regions (P = 0.354), and there were no interactions between light type and region (P = 0.368). Conclusions LED leaves less residual monomer than does the halogen light, even with half of the irradiation time; there were no differences between the central and peripheral regions, and no interaction between light type and region. PMID:21055603

  9. ASCORBIC ACID TREATMENT TO REDUCE RESIDUAL HALOGEN-BASED OXIDANTS PRIOR TO THE DETERMINATION OF HALOGENATED DISINFECTION BYPRODUCTS IN POTABLE WATER

    EPA Science Inventory

    Treatment of potable water samples with ascorbic acid has been investigated as a means for reducing residual halogen-based oxidants (disinfectants)i.e., HOCl, Cl2, Brw and BrCl, prior to determination of EPA Method 551.1A and 551.1B analytes. These disinfection byproducts include...

  10. FIELD SCREENING FOR HALOGENATED VOLATILE ORGANIC COMPOUNDS

    SciTech Connect

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

    2002-06-01

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

  11. Solar radiation absorbing material

    DOEpatents

    Googin, John M.; Schmitt, Charles R.; Schreyer, James M.; Whitehead, Harlan D.

    1977-01-01

    Solar energy absorbing means in solar collectors are provided by a solar selective carbon surface. A solar selective carbon surface is a microporous carbon surface having pores within the range of 0.2 to 2 micrometers. Such a surface is provided in a microporous carbon article by controlling the pore size. A thermally conductive substrate is provided with a solar selective surface by adhering an array of carbon particles in a suitable binder to the substrate, a majority of said particles having diameters within the range of about 0.2-10 microns.

  12. Halogenation of graphene with chlorine, bromine, or iodine by exfoliation in a halogen atmosphere.

    PubMed

    Poh, Hwee Ling; Šimek, Petr; Sofer, Zdeněk; Pumera, Martin

    2013-02-18

    Nanoarchitectonics on graphene implicates a specific and exact anchoring of molecules or nanoparticles onto the surface of graphene. One such example of an effective anchoring group that is highly reactive is the halogen moiety. Herein we describe a simple and scalable method for the introduction of halogen (chlorine, bromine, and iodine) moieties onto the surface of graphene by thermal exfoliation/reduction of graphite oxide in the corresponding gaseous halogen atmosphere. We characterized the halogenated graphene by using various techniques, including scanning and transmission electron microscopy, Raman spectroscopy, high-resolution X-ray photoelectron spectroscopy, and electrochemistry. The halogen atoms that have successfully been attached to the graphene surfaces will serve as basic building blocks for further graphene nanoarchitectonics. PMID:23296548

  13. Treatment System for Removing Halogenated Compounds from Contaminated Sources

    NASA Technical Reports Server (NTRS)

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

  14. Biodegradation of halogenated organic compounds.

    PubMed Central

    Chaudhry, G R; Chapalamadugu, S

    1991-01-01

    In this review we discuss the degradation of chlorinated hydrocarbons by microorganisms, emphasizing the physiological, biochemical, and genetic basis of the biodegradation of aliphatic, aromatic, and polycyclic compounds. Many environmentally important xenobiotics are halogenated, especially chlorinated. These compounds are manufactured and used as pesticides, plasticizers, paint and printing-ink components, adhesives, flame retardants, hydraulic and heat transfer fluids, refrigerants, solvents, additives for cutting oils, and textile auxiliaries. The hazardous chemicals enter the environment through production, commercial application, and waste. As a result of bioaccumulation in the food chain and groundwater contamination, they pose public health problems because many of them are toxic, mutagenic, or carcinogenic. Although synthetic chemicals are usually recalcitrant to biodegradation, microorganisms have evolved an extensive range of enzymes, pathways, and control mechanisms that are responsible for catabolism of a wide variety of such compounds. Thus, such biological degradation can be exploited to alleviate environmental pollution problems. The pathways by which a given compound is degraded are determined by the physical, chemical, and microbiological aspects of a particular environment. By understanding the genetic basis of catabolism of xenobiotics, it is possible to improve the efficacy of naturally occurring microorganisms or construct new microorganisms capable of degrading pollutants in soil and aquatic environments more efficiently. Recently a number of genes whose enzyme products have a broader substrate specificity for the degradation of aromatic compounds have been cloned and attempts have been made to construct gene cassettes or synthetic operons comprising these degradative genes. Such gene cassettes or operons can be transferred into suitable microbial hosts for extending and custom designing the pathways for rapid degradation of recalcitrant

  15. Biodegradation of halogenated organic compounds.

    PubMed

    Chaudhry, G R; Chapalamadugu, S

    1991-03-01

    In this review we discuss the degradation of chlorinated hydrocarbons by microorganisms, emphasizing the physiological, biochemical, and genetic basis of the biodegradation of aliphatic, aromatic, and polycyclic compounds. Many environmentally important xenobiotics are halogenated, especially chlorinated. These compounds are manufactured and used as pesticides, plasticizers, paint and printing-ink components, adhesives, flame retardants, hydraulic and heat transfer fluids, refrigerants, solvents, additives for cutting oils, and textile auxiliaries. The hazardous chemicals enter the environment through production, commercial application, and waste. As a result of bioaccumulation in the food chain and groundwater contamination, they pose public health problems because many of them are toxic, mutagenic, or carcinogenic. Although synthetic chemicals are usually recalcitrant to biodegradation, microorganisms have evolved an extensive range of enzymes, pathways, and control mechanisms that are responsible for catabolism of a wide variety of such compounds. Thus, such biological degradation can be exploited to alleviate environmental pollution problems. The pathways by which a given compound is degraded are determined by the physical, chemical, and microbiological aspects of a particular environment. By understanding the genetic basis of catabolism of xenobiotics, it is possible to improve the efficacy of naturally occurring microorganisms or construct new microorganisms capable of degrading pollutants in soil and aquatic environments more efficiently. Recently a number of genes whose enzyme products have a broader substrate specificity for the degradation of aromatic compounds have been cloned and attempts have been made to construct gene cassettes or synthetic operons comprising these degradative genes. Such gene cassettes or operons can be transferred into suitable microbial hosts for extending and custom designing the pathways for rapid degradation of recalcitrant

  16. Halogen Radical Chemistry at Aqueous Interfaces.

    PubMed

    Enami, Shinichi; Hoffmann, Michael R; Colussi, A J

    2016-08-11

    Halogens play key roles in the chemical composition of marine boundary layers, the free troposphere and the stratosphere. Atmospheric halogen chemistry is dominated by reactions between gas-phase and aqueous species on the surfaces of the ocean and marine aerosol. The mechanisms of interfacial halogen radical/halide reactions, however, are not fully understood, partly due to the dearth of techniques for in situ monitoring of the products and intermediates of fast interfacial halogen radical reactions. Here, we report the online electrospray mass spectrometric identification of the species produced on the surface of aqueous Br(-) and I(-) microjets collided by I(•)(g) pulses generated from the 266 nm laser photolysis of CH3I/O2/N2 gas mixtures. Mass-specific identification of intermediates and products in D2O and H2(18)O solutions and their dependences on I(•)(g) fluxes let us outline mechanisms of formation. We found that the uptake of I(•)(g) on the surface of Br(-) and I(-) microjets (effective uptake coefficient γeff ≥ 2 × 10(-4)) yields IBr(•)(-)/I2(•)(-) radical intermediates, which rapidly react with additional I(•) to produce trihalides I2Br(-)/IBr2(-)/I3(-) plus I3On(-) (n = 1, 2) species within ∼10 μs. Our findings point to a new halogen activation pathway initiated by photogenerated I(•). PMID:27414750

  17. 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.

  18. Investigation of Halogenated Components Formed from Chlorination of Natural Waters: Preliminary Studies

    SciTech Connect

    Bean, R. M.; Riley, R. G.

    1980-11-01

    Chlorination of power plant cooling water is extensively used as a means of controlling biofouling. This practice presents the potential for formation of halogenated organic compounds hazardous to man and his environment. Accordingly, the organic composition resulting from the chlorination of natural waters (northern Olympic Penn1sula sea water and the Columbia River in Washington State} has been investigated. Nonpolar lipophilic organic halogens were extracted by passing large volumes of water over columns of XAD-2 macroreticular resins. Examination of ether extracts from the resin columns using capillary gas chromatography revealed the presence of halogenated methanes, as well as other electron-capturing components~ that were not found when unchlorinated water was sampled. Examination of the chlorinated water extracts using gas chromatography/mass spectrometry revealed complex mixtures which generally were not separable into individual components~ even when high efficiency WCOT capillary columns were used. The samples were separated into fractions of increasing polarity using a water-deactivated silica gel column. Fractions were thus obtained which were more amenable to GC/MS investigation. Haloforms were identified as the major halogenated product from chlorination of the waters studied. Other halogenated products were found at much lower concentrations.

  19. 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.

  20. 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.

  1. Determination of small halogenated carboxylic acid residues in drug substances by high performance liquid chromatography-diode array detection following derivatization with nitro-substituted phenylhydrazines.

    PubMed

    Hou, Desheng; Fan, Jingjing; Han, Lingfei; Ruan, Xiaoling; Feng, Feng; Liu, Wenyuan; Zheng, Feng

    2016-03-18

    A method for the determination of small halogenated carboxylic acid (HCA) residues in drug substances is urgently needed because of the potential of HCAs for genotoxicity and carcinogenicity in humans. We have now developed a simple method, involving derivatization followed by high performance liquid chromatography-diode array detection (HPLC-DAD), for the determination of six likely residual HCAs (monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, 2-chloropropionic acid, 2-bromopropionic acid and 3-chloropropionic acid) in drug substances. Different nitro-substituted phenylhydrazines (NPHs) derivatization reagents were systematically compared and evaluated. 2-Nitrophenylhydrazine hydrochloride (2-NPH·HCl) was selected as the most suitable choice since its derivatives absorb strongly at 392 nm, a region of the spectrum where most drug substances and impurities absorb very weakly. During the derivatization process, the commonly used catalyst, pyridine, caused rapid dechlorination or chlorine substitution of α-halogenated derivatives. To avoid these unwanted side reactions, a reliable derivatization method that did not use pyridine was developed. Reaction with 2-NPH·HCl using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as coupling agent in acetonitrile-water (70:30) at room temperature for 2h gave complete reaction and avoided degradation products. The derivatives were analyzed, without any pretreatment, using gradient HPLC with detection in the near visible region. Organic acids commonly found in drug substances and other impurities did not interfere with the analysis. Good linearity (r>0.999) and low limits of quantitation (0.05-0.12 μg mL(-1)) were obtained. The mean recoveries were in the range of 80-115% with RSD <5.81% except for 3-CPA in ibuprofen which was 78.5%. The intra- and inter-day precisions were expressed as RSD <1.98% and <4.39%, respectively. Finally, the proposed method was successfully used for the residue

  2. NOXIOUS TRACE GASES IN THE AIR. PART II. HALOGENATED POLLUTANTS

    EPA Science Inventory

    The chemistry of chlorofluorocarbons and other halogenated air pollutants is discussed. A summary is presented of the present levels of concentration of such compounds, along with comments on anticipated increases. Chemical reactions that transform and remove halogenated pollutan...

  3. Evaluation of halogenated coumarins for antimosquito properties.

    PubMed

    Narayanaswamy, Venugopala K; Gleiser, Raquel M; Kasumbwe, Kabange; Aldhubiab, Bandar E; Attimarad, Mahesh V; Odhav, Bharti

    2014-01-01

    Mosquitoes are the major vectors of parasites and pathogens affecting humans and domestic animals. The widespread development of insecticide resistance and negative environmental effects of most synthetic compounds support an interest in finding and developing alternative products against mosquitoes. Natural coumarins and synthetic coumarin analogues are known for their several pharmacological properties, including being insecticidal. In the present study halogenated coumarins (3-mono/dibromo acetyl, 6-halogenated coumarin analogues) were screened for larvicidal, adulticidal, and repellent properties against Anopheles arabiensis, a zoophilic mosquito that is one of the dominant vectors of malaria in Africa. Five compounds exerted 100% larval mortality within 24 h of exposure. All coumarins and halogenated coumarins reversibly knocked down adult mosquitoes but did not kill them after 24 h of exposure. Repellent properties could not be evidenced. Five compounds were considered potential larvicidal agents for further research and development, while adulticidal activity was considered only mild to moderate. PMID:25610898

  4. Evaluation of Halogenated Coumarins for Antimosquito Properties

    PubMed Central

    Narayanaswamy, Venugopala K.; Gleiser, Raquel M.; Kasumbwe, Kabange; Aldhubiab, Bandar E.; Attimarad, Mahesh V.; Odhav, Bharti

    2014-01-01

    Mosquitoes are the major vectors of parasites and pathogens affecting humans and domestic animals. The widespread development of insecticide resistance and negative environmental effects of most synthetic compounds support an interest in finding and developing alternative products against mosquitoes. Natural coumarins and synthetic coumarin analogues are known for their several pharmacological properties, including being insecticidal. In the present study halogenated coumarins (3-mono/dibromo acetyl, 6-halogenated coumarin analogues) were screened for larvicidal, adulticidal, and repellent properties against Anopheles arabiensis, a zoophilic mosquito that is one of the dominant vectors of malaria in Africa. Five compounds exerted 100% larval mortality within 24 h of exposure. All coumarins and halogenated coumarins reversibly knocked down adult mosquitoes but did not kill them after 24 h of exposure. Repellent properties could not be evidenced. Five compounds were considered potential larvicidal agents for further research and development, while adulticidal activity was considered only mild to moderate. PMID:25610898

  5. Halogen Oxide Measurements at Masaya Volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Kern, C.; Vogel, L.; Sihler, H.; Rivera, C.; Strauch, W.; Galle, B.; Platt, U.

    2007-12-01

    Sulphur dioxide (SO2) and halogen oxide emissions were measured at Masaya Volcano in Nicaragua in April 2007 using differential optical absorption spectroscopy (DOAS). Next to passive DOAS measurements using scattered sunlight, an active long-path DOAS system was operated for several days with the light beam crossing the crater of the volcano. These measurements for the first time give an insight into the night-time halogen chemistry occurring at volcanoes. While the passive DOAS instruments measured sulphur dioxide (SO2) and bromine monoxide (BrO) in various viewing geometries and distances from the crater during daytime, the active instrument additionally allowed a quantification of chlorine monoxide (ClO) and chlorine dioxide (OClO), as well as being able to measure round-the-clock. The results of the field measurements will be presented and their implications for halogen chemistry at volcanoes will be discussed.

  6. 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. PMID:18837495

  7. Halogen chemistry in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Plane, J. M. C.; Gomez Martin, J. C.; Kumar, R.; Mahajan, A. S.; Oetjen, H.; Saunders, R. W.

    2009-04-01

    Important atmospheric sources of iodine include the air-sea exchange of biogenic iodocarbons, and the emission of I2 from macro-algae. The major source of bromine is the release of bromide ions from sea-salt aerosol. The subsequent atmospheric chemistry of these halogens (1), changes the oxidizing capacity of the marine boundary layer by destroying ozone and changing the hydroxyl radical concentration; (2), reacts efficiently with dimethyl sulphide and mercury (in the polar regions); and (3), leads to the formation of ultra-fine particles which may contribute to cloud condensation nuclei (CCN) and hence affect climate. This paper will report observations of IO, BrO, OIO and I2 made by the technique of differential optical absorption spectroscopy, in several contrasting marine environments: the equatorial mid-Atlantic (Cape Verde); mid-latitude clean coastal (Mace Head, Ireland); polluted coastal (Roscoff, France); and the polar marine boundary layer (Hudson Bay, Canada). Both IO and BrO are observed in all these locations at significant concentrations (> 1 pptv), and so have a major impact on (1) and (2) above. To complement the field campaigns we have also carried out wide-ranging laboratory investigation. A new study of OIO photochemistry shows that absorption in the visible bands between 490 and 630 nm leads to I atom production with a quantum yield of unity, which now means that iodine is a particularly powerful ozone-depleting agent. We have also studied the formation and growth kinetics of iodine oxide nano-particles, and their uptake of water, sulphuric acid and di-carboxylic organic acids, in order to model their growth to a size where they can act as CCN. Their ice-nucleating properties will also be reported.

  8. 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.

  9. Palladium-Catalyzed Carbamate-Directed Regioselective Halogenation: A Route to Halogenated Anilines.

    PubMed

    Moghaddam, Firouz Matloubi; Tavakoli, Ghazal; Saeednia, Borna; Langer, Peter; Jafari, Behzad

    2016-05-01

    This study describes an efficient method for ortho-selective halogenation of N-arylcarbamates under mild conditions for the first time. Although being weakly coordinating, N-arylcarbamates act very well as a removable directing group for activation of C-H bonds. The developed procedure results in extremely valuable halogenated N-arylcarbmates that can further be hydrolyzed to halogenated anilines. The obtained reaction conditions showed broad scope and wide functional group tolerance. All the products were formed in good yields with extremely high selectivity. PMID:27072283

  10. Boundary layer halogens in coastal Antarctica.

    PubMed

    Saiz-Lopez, Alfonso; Mahajan, Anoop S; Salmon, Rhian A; Bauguitte, Stephane J-B; Jones, Anna E; Roscoe, Howard K; Plane, John M C

    2007-07-20

    Halogens influence the oxidizing capacity of Earth's troposphere, and iodine oxides form ultrafine aerosols, which may have an impact on climate. We report year-round measurements of boundary layer iodine oxide and bromine oxide at the near-coastal site of Halley Station, Antarctica. Surprisingly, both species are present throughout the sunlit period and exhibit similar seasonal cycles and concentrations. The springtime peak of iodine oxide (20 parts per trillion) is the highest concentration recorded anywhere in the atmosphere. These levels of halogens cause substantial ozone depletion, as well as the rapid oxidation of dimethyl sulfide and mercury in the Antarctic boundary layer. PMID:17641195

  11. HALOGEN: Approximate synthetic halo catalog generator

    NASA Astrophysics Data System (ADS)

    Avila Perez, Santiago; Murray, Steven

    2015-05-01

    HALOGEN generates approximate synthetic halo catalogs. Written in C, it decomposes the problem of generating cosmological tracer distributions (eg. halos) into four steps: generating an approximate density field, generating the required number of tracers from a CDF over mass, placing the tracers on field particles according to a bias scheme dependent on local density, and assigning velocities to the tracers based on velocities of local particles. It also implements a default set of four models for these steps. HALOGEN uses 2LPTic (ascl:1201.005) and CUTE (ascl:1505.016); the software is flexible and can be adapted to varying cosmologies and simulation specifications.

  12. Halogenated silanes, radicals, and cations

    NASA Astrophysics Data System (ADS)

    Wang, Liming; He, Yi-Liang

    2008-09-01

    Quantum chemistry study has been carried out on the structure and energetics of halogenated silanes, radicals, and cations (SiHxXy0,+1, X = F, Cl, Br; x + y = 1-4). The geometries are optimized at B3LYP/6-31+G(2df,p) level. The adiabatic ionization energiess (IEas), relative energetics of cations, proton affinities (PAs) of silanes, and the enthalpies of formation are predicted using G3(CC) model chemistry. Non-classical ion complex structures are found for hydrogenated cations and transition states connecting classical and non-classical structures are also located. The most stable cations for silylene and silyl radicals have their classical divalent and trivalent structures, and those for silanes have non-classical structures except for SiH3Br+ and SiH2Br2+. The non-classical structures for halosilane cations imply difficulty in experimentally measurement of the adiabatic ionization energies using photoionization or photoelectron studies. For SiH3X, SiH2X2, and SiHX3, the G3(CC) adiabatic IEas to classical ionic structures closest to their neutrals agree better with the photoelectron spectroscopic measurements. The transition states between classical and non-classical structures also hamper the photoionization determination of the appearance energies for silylene cations from silanes. The G3(CC) results for SiHx0,+1 agree excellently with the photoionization mass spectrometric study, and the results for fluorinated and chlorinated species also agree with the previous theoretical predictions at correlation levels from BAC-MP4 to CCSD(T)/CBS. The predicted enthalpy differences between SiH2Cl+, SiHCl2+, and SiCl3+ are also in accordance with previous kinetics study. The G3(CC) results show large discrepancies to the collision-induced charge transfer and/or dissociation reactions involving SiFx+ and SiClx+ ions, for which the G3(CC) enthalpies of formation are also significantly differed from the previous theoretical predictions, especially on SiFx+ (x = 2-4). The G3

  13. 40 CFR 721.5546 - Halogen substituted oxetanes (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Halogen substituted oxetanes (generic... Substances § 721.5546 Halogen substituted oxetanes (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as halogen substituted...

  14. 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.

  15. 40 CFR 721.5546 - Halogen substituted oxetanes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Halogen substituted oxetanes (generic... Substances § 721.5546 Halogen substituted oxetanes (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as halogen substituted...

  16. 40 CFR 721.5546 - Halogen substituted oxetanes (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Halogen substituted oxetanes (generic... Substances § 721.5546 Halogen substituted oxetanes (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as halogen substituted...

  17. 40 CFR 721.5546 - Halogen substituted oxetanes (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halogen substituted oxetanes (generic... Substances § 721.5546 Halogen substituted oxetanes (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as halogen substituted...

  18. 40 CFR 721.5546 - Halogen substituted oxetanes (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Halogen substituted oxetanes (generic... Substances § 721.5546 Halogen substituted oxetanes (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as halogen substituted...

  19. 40 CFR 721.10259 - Halogenated aromatic hydrocarbon (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Halogenated aromatic hydrocarbon... Specific Chemical Substances § 721.10259 Halogenated aromatic hydrocarbon (generic). (a) Chemical substance... halogenated aromatic hydrocarbon (PMN P-09-540) is subject to reporting under this section for the...

  20. 40 CFR 721.10259 - Halogenated aromatic hydrocarbon (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Halogenated aromatic hydrocarbon... Specific Chemical Substances § 721.10259 Halogenated aromatic hydrocarbon (generic). (a) Chemical substance... halogenated aromatic hydrocarbon (PMN P-09-540) is subject to reporting under this section for the...

  1. 40 CFR 721.10259 - Halogenated aromatic hydrocarbon (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Halogenated aromatic hydrocarbon... Specific Chemical Substances § 721.10259 Halogenated aromatic hydrocarbon (generic). (a) Chemical substance... halogenated aromatic hydrocarbon (PMN P-09-540) is subject to reporting under this section for the...

  2. NXY halogen bonds. Comparison with NHY H-bonds and CXY halogen bonds.

    PubMed

    Nepal, Binod; Scheiner, Steve

    2016-07-21

    Quantum calculations examine how the NHY H-bond compares to the equivalent NXY halogen bond, as well as to comparable CH/CX donors. Succinimide and saccharin, and their corresponding halogen-substituted derivatives, are chosen as the prototype NH/NX donors, paired with a wide range of electron donor molecules. The NHY H-bond is weakened if the bridging H is replaced by Cl, and strengthened by I; a Br halogen bond is roughly comparable to a H-bond. The lone pairs of the partner molecule are stronger electron donors than are π-systems. Whereas Coulombic forces represent the largest fraction of the attractive force in the H-bonds, induction energy is magnified in the halogen bonds, surpassing electrostatics in several cases. Mutation of NH/NX to CH/CX weakens the binding energy to roughly half its original value, while also lengthening the intermolecular distances by 0.3-0.8 Å. PMID:27327538

  3. Herringbone structures of 2,7-dihalogenated acridine tailored by halogen-halogen interactions

    NASA Astrophysics Data System (ADS)

    Yamamura, Masaki; Ikuma, Seira; Nabeshima, Tatsuya

    2015-08-01

    The crystal structures of the 2,7-dibromo- and 2,7-diiodoacridines (2 and 3) were determined by single-crystal X-ray diffraction analysis. Molecules of the brominated 2 were assembled through different types of halogen-halogen interactions (Type-I and Type-II). Conversely, molecules of the iodinated 3 were assembled only through Type-II interactions. Although both compounds were packed in a herringbone way, the intermolecular π-π stacking was observed only in the brominated 2. In the solution and solid-state absorption spectra, a bathochromic shift in the absorption was observed, as the mass of the halogen atoms increased. Theoretical calculation indicated a substituent effect of the halogen on the π-orbital of the acridine moiety. In the solid state, the iodinated 3 exhibited a significant absorption in the orange-to-red wavelength region.

  4. Adaptive inertial shock-absorber

    NASA Astrophysics Data System (ADS)

    Faraj, Rami; Holnicki-Szulc, Jan; Knap, Lech; Seńko, Jarosław

    2016-03-01

    This paper introduces and discusses a new concept of impact absorption by means of impact energy management and storage in dedicated rotating inertial discs. The effectiveness of the concept is demonstrated in a selected case-study involving spinning management, a recently developed novel impact-absorber. A specific control technique performed on this device is demonstrated to be the main source of significant improvement in the overall efficiency of impact damping process. The influence of various parameters on the performance of the shock-absorber is investigated. Design and manufacturing challenges and directions of further research are formulated.

  5. Retention of Halogens in Waste Glass

    SciTech Connect

    Hrma, Pavel R.

    2010-05-01

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

  6. 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...

  7. 40 CFR 721.505 - Halogenated acrylonitrile.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... reporting. (1) The chemical substance identified generically as halogenated acrylonitrile, (PMN P-90-299) is... specified in § 721.125 (a) through (h). (2) Limitations or revocation of certain notification requirements... Section 721.505 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC...

  8. 40 CFR 721.505 - Halogenated acrylonitrile.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... reporting. (1) The chemical substance identified generically as halogenated acrylonitrile, (PMN P-90-299) is... specified in § 721.125 (a) through (h). (2) Limitations or revocation of certain notification requirements... Section 721.505 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC...

  9. ALIPHATIC HALOGENATED HYDROCARBONS PRODUCE VOLATILE 'SALMONELLA' MUTAGENS

    EPA Science Inventory

    Production of volatile mutagenic metabolites from 5 halogenated promutagens was examined by a simple modification of the conventional Salmonella/microsome mutagenicity assay. This method incorporates the taping together of 2 agar plates face to face during the initial portion of ...

  10. Iron Catalyzed Halogenation Processes in Saline Soils

    NASA Astrophysics Data System (ADS)

    Tubbesing, C.; Lippe, S.; Kullik, V.; Hauck, L.; Krause, T.; Keppler, F.; Schoeler, H. F.

    2014-12-01

    Within upcoming years the extent of salt deserts and salt lakes will probably increase due to climate change. It is known that volatile organic halogens (VOX) are released from saline soils and thus higher emissions from these environments are likely expected in the future. The origin of some organohalogens is not reasonably constrained by established natural halogenation processes. Therefore detailed biogeochemical investigations of these environments are necessary to identify the specific halogenation pathways. Redox-sensitive metals like iron are already known as triggers of chemical reactions via so called Fenton and Fenton-like reactions requiring H2O2 which is photochemically produced in water. In this study we collected soil samples from several salt lakes in Western Australia with pH values ranging from 2 to 8. The high pH variability was considered useful to study the impact of iron mobility and availability on halogenation processes. Iron was found to mainly occur as oxides and sulfides within the alkaline soils and acidic soils, respectively. All soil samples were lyophilised and finely ground prior to incubation at 40 °C for 24 h in aqueous solutions. Formation of volatile organic compounds (VOC) and VOX from these soils was observed using GC-FID and GC-MS. When H2O2 was added to the samples much higher concentrations of VOC and VOX were observed. Furthermore, when the pH of the soils was changed towards lower values higher emissions of VOC were also observed. Based on C-H activation processes we delineate a halide containing iron complex as a provider of anions reacting with previously generated hydrocarbon radicals. We suggest iron sulfate derivatives as those complexes which are generated if the above-mentioned natural H2O2 addition to iron sulfates and sulfides occurs. The origin of these complexes is able to explain the halogenation of chemically unreactive alkanes.

  11. Composition for absorbing hydrogen

    DOEpatents

    Heung, L.K.; Wicks, G.G.; Enz, G.L.

    1995-05-02

    A hydrogen absorbing composition is described. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  12. Composition for absorbing hydrogen

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Enz, Glenn L.

    1995-01-01

    A hydrogen absorbing composition. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  13. Determination of halogens and sulfur in high-purity polyimide by IC after digestion by MIC.

    PubMed

    Krzyzaniak, Sindy R; Santos, Rafael F; Dalla Nora, Flavia M; Cruz, Sandra M; Flores, Erico M M; Mello, Paola A

    2016-09-01

    In this work, a method for sample preparation of high-purity polyimide was proposed for halogens and sulfur determination by ion chromatography (IC) with conductivity detection and, alternatively, by inductively coupled plasma mass spectrometry (ICP-MS). A relatively high polyimide mass (600mg) was completely digested by microwave-induced combustion (MIC) using 20bar of O2 and 50mmolL(-1) NH4OH as absorbing solution. These conditions allowed final solutions with low carbon content (<10mgL(-1)) and suitable pH for analysis by both IC and ICP-MS. The accuracy was evaluated using a certified reference material of polymer for Cl, Br and S and spike recovery experiments for all analytes. No statistical difference (t-test, 95% of confidence level) was observed between the results obtained for Cl, Br and S by IC after MIC and the certified values. In addition, spike recoveries obtained for F, Cl, Br, I and S ranged from 94% to 101%. The proposed method was suitable for polyimide decomposition for further determination of halogens and sulfur by IC and by ICP-MS (Br and I only). Taking into account the lack of methods and the difficulty of bringing this material into solution, MIC can be considered as a suitable alternative for the decomposition of polyimide for routine quality control of halogens and sulfur using IC or ICP-MS. PMID:27343595

  14. Modelling Absorbent Phenomena of Absorbent Structure

    NASA Astrophysics Data System (ADS)

    Sayeb, S.; Ladhari, N.; Ben Hassen, M.; Sakli, F.

    Absorption, retention and strike through time, as evaluating criteria of absorbent structures quality were studied. Determination of influent parameters on these criteria were realized by using the design method of experimental sets. In this study, the studied parameters are: Super absorbent polymer (SAP)/fluff ratio, compression and the porosity of the non woven used as a cover stock. Absorption capacity and retention are mostly influenced by SAP/fluff ratio. However, strike through time is affected by compression. Thus, a modelling of these characteristics in function of the important parameter was established.

  15. Halogen bonding origin properties and applications

    SciTech Connect

    Hobza, Pavel

    2015-12-31

    σ-hole bonding represents an unusual and novel type of noncovalent interactions in which atom with σ- hole interacts with Lewis base such as an electronegative atom (oxygen, nitrogen, …) or aromatic systems. This bonding is of electrostatic nature since the σ-hole bears a positive charge. Dispersion energy forms equally important energy term what is due to the fact that two heavy atoms (e.g. halogen and oxygen) having high polarizability lie close together (the respective distance is typically shorter than the sum of van der Waals radii). Among different types of σ-hole bondings the halogen bonding is by far the most known but chalcogen and pnictogen bondings are important as well.

  16. 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.

  17. Halogenating activities detected in Antarctic macroalgae

    SciTech Connect

    Laturnus, F.; Adams, F.C.; Gomez, I.; Mehrtens, G.

    1997-03-01

    Halogenating activities were determined in samples of 18 cultivated species of brown, red and green macroalgae from the Antarctic. Activities for the halogenating organic compounds with bromide, iodide and chloride were found. Investigated red algae (rhodophytes) showed higher brominating and iodinating activities compared to brown (phaeophytes) and green (chlorophytes) algae. The highest brominating and iodinating activities were measured in the red algae Plocamium cartilagineum (1.11 {+-} 0.01 U g{sup -1} wet algal weight and 0.18 U g{sup -1} wet algal weight, respectively) and Myriogramme mangini (3.62 {+-} 0.17 U g{sup -1} wet algal weight and 4.5 U g{sup -1} wet algal weight, respectively). Chlorinating activities were detected in the red alga Plocamium cartilagineum only (0.086 U g{sup -1} wet algal weight). 30 refs., 2 figs., 1 tab.

  18. Methods for absorbing neutrons

    DOEpatents

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  19. Externally tuned vibration absorber

    DOEpatents

    Vincent, Ronald J.

    1987-09-22

    A vibration absorber unit or units are mounted on the exterior housing of a hydraulic drive system of the type that is powered from a pressure wave generated, e.g., by a Stirling engine. The hydraulic drive system employs a piston which is hydraulically driven to oscillate in a direction perpendicular to the axis of the hydraulic drive system. The vibration absorbers each include a spring or other resilient member having one side affixed to the housing and another side to which an absorber mass is affixed. In a preferred embodiment, a pair of vibration absorbers is employed, each absorber being formed of a pair of leaf spring assemblies, between which the absorber mass is suspended.

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    Reactive halogen species (RHS), such as X·, X2 and HOX containing X = chlorine and/or bromine, are released by various sources like photo-activated sea-salt aerosol or from salt pans, and salt lakes. Despite many studies of RHS reactions, the potential of RHS reacting with secondary organic aerosol (SOA) and organic aerosol derived from biomass-burning (BBOA) has been neglected. Such reactions can constitute sources of gaseous organohalogen compounds or halogenated organic matter in the tropospheric boundary layer and can influence physicochemical properties of atmospheric aerosols. Model SOA from α-pinene, catechol, and guaiacol was used to study heterogeneous interactions with RHS. Particles were exposed to molecular chlorine and bromine in an aerosol smog-chamber in the presence of UV/VIS irradiation and to RHS released from simulated natural halogen sources like salt pans. Subsequently the aerosol was characterized in detail using a variety of physicochemical and spectroscopic methods. Fundamental features were correlated with heterogeneous halogenation, which result in new functional groups, changed UV/VIS absorption, or aerosol size distribution. However, the halogen release mechanisms were also found to be affected by the presence of organic aerosol. Those interaction processes, changing chemical and physical properties of the aerosol are likely to influence e.g. the ability of the aerosol to act as cloud condensation nuclei, its potential to adsorb other gases with low-volatility, or its contribution to radiative forcing and ultimately the Earth's radiation balance.

  1. 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.

  2. 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.

  3. Computational Tools To Model Halogen Bonds in Medicinal Chemistry.

    PubMed

    Ford, Melissa Coates; Ho, P Shing

    2016-03-10

    The use of halogens in therapeutics dates back to the earliest days of medicine when seaweed was used as a source of iodine to treat goiters. The incorporation of halogens to improve the potency of drugs is now fairly standard in medicinal chemistry. In the past decade, halogens have been recognized as direct participants in defining the affinity of inhibitors through a noncovalent interaction called the halogen bond or X-bond. Incorporating X-bonding into structure-based drug design requires computational models for the anisotropic distribution of charge and the nonspherical shape of halogens, which lead to their highly directional geometries and stabilizing energies. We review here current successes and challenges in developing computational methods to introduce X-bonding into lead compound discovery and optimization during drug development. This fast-growing field will push further development of more accurate and efficient computational tools to accelerate the exploitation of halogens in medicinal chemistry. PMID:26465079

  4. Infrared Spectroscopy of Halogenated Species for Atmospheric Remote Sensing

    NASA Astrophysics Data System (ADS)

    Harrison, Jeremy J.

    2014-06-01

    Fluorine- and chlorine-containing molecules in the atmosphere are very strong greenhouse gases, meaning that even small amounts of these gases contribute significantly to the radiative forcing of climate. Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are regulated by the 1987 Montreal Protocol because they deplete the ozone layer. Hydrofluorocarbons (HFCs), which do not deplete the ozone layer and are not regulated by the Montreal Protocol, have been introduced as replacements for CFCs and HCFCs. HFCs have global-warming potentials many times greater than carbon dioxide, and are increasing in the atmosphere at a very fast rate. Various satellite instruments monitor many of these molecules by detecting infrared radiation that has passed through the Earth's atmosphere. However, the quantification of their atmospheric abundances crucially requires accurate quantitative infrared spectroscopy. This talk will focus on new and improved laboratory spectroscopic measurements for a number of important halogenated species.

  5. Direct conversion of halogen-containing wastes to borosilicate glass

    SciTech Connect

    Forsberg, C.W.; Beahm, E.C.; Rudolph, J.C.

    1996-12-09

    Glass has become a preferred waste form worldwide for radioactive wastes: however, there are limitations. Halogen-containing wastes can not be converted to glass because halogens form poor-quality waste glasses. Furthermore, halides in glass melters often form second phases that create operating problems. A new waste vitrification process, the Glass Material Oxidation and dissolution System (GMODS), removes these limitations by converting halogen-containing wastes into borosilicate glass and a secondary, clean, sodium-halide stream.

  6. Potential halogenated industrial carcinogenic and mutagenic chemicals. II. Halogenated saturated hydrocarbons.

    PubMed

    Fishbein, L

    1979-03-01

    The halogenated saturated hydrocarbons analogously to the previously considered halogenated unsaturated hydrocarbons (Part I) possess considerable utility in a broad spectrum of applications including; solvents, dry-cleaning fluids, refrigerants, fumigants, degreasing agents, propellants and intermediates in the production of other chemicals, textiles and plastics. Methyl chloride, methylene chloride, chloroform, carbon tetrachloride, methyl chloroform, 1,1,2-trichloroethane, hexachloroethane, ethyl chloride and fluorocarbons were reviewed principally in terms of their synthesis (or occurrence), areas of application, stability, distribution, reactivity, levels of exposure, populations at risk, carcinogenicity, mutagenicity and metabolism. PMID:373115

  7. Hexahalogenated and their mixed benzene derivatives as prototypes for the understanding of halogen···halogen intramolecular interactions: New insights from combined DFT, QTAIM-, and RDG-based NCI analyses.

    PubMed

    Varadwaj, Pradeep R; Varadwaj, Arpita; Jin, Bih-Yaw

    2015-12-01

    A large number of fully halogenated benzene derivatives containing the fluorine, chlorine, bromine, and iodine atoms have been experimentally synthesized both as single- and co-crystals (e.g., Desiraju et al., Chem. Eur. J. 2006, 12, 2222), yet the natures of the halogen ··· halogen interactions between the vicinal halogens in these compounds within the intramolecular domain are undisclosed. Given a fundamental understanding of these interactions is incredibly important in many areas of chemical, biological, supramolecular, and material sciences, we present here our newly discovered theoretical results that delineate whilst the nature of an F···F interaction in a pair of two adjacent fluorine atoms in either of the hexafluorobenzene and 1,4-dibromotetrafluorobenzene compounds examined is almost unclear, each of the latter three hexahalogenated benzene derivatives (viz., C6 Cl6 , C6 Br6 , and C6 I6 ), and each of the seven of their fully mixed hexahalogenated benzene analogues, are found to be stabilized by means of a number of halogen···halogen interactions, each a form of long-range attraction within the intramolecular domain. The Molecular Electrostatic Surface Potential model was found to be unsurprisingly unsuitable in unraveling any of the aforesaid attractions between the halogen atoms. However, such interactions successfully enunciated by a set of noncovalent interaction descriptors of geometrical, topological, and electrostatic origins. These latter properties were extracted combining the results of the Density Functional Theory electronic structure calculations with those revealed from Atoms in Molecules, and Reduced Density Gradient charge density-based topological calculations, and are expounded in detail to formalize the conclusions. © 2015 Wiley Periodicals, Inc. PMID:26505258

  8. Plants absorb heavy metals

    SciTech Connect

    Parry, J.

    1995-02-01

    Decontamination of heavy metals-polluted soils remains one of the most intractable problems of cleanup technology. Currently available techniques include extraction of the metals by physical and chemical means, such as acid leaching and electroosmosis, or immobilization by vitrification. There are presently no techniques for cleanup which are low cost and retain soil fertility after metals removal. But a solution to the problem could be on the horizon. A small but growing number of plants native to metalliferous soils are known to be capable of accumulating extremely high concentrations of metals in their aboveground portions. These hyperaccumulators, as they are called, contain up to 1,000 times larger metal concentrations in their aboveground parts than normal species. Their distribution is global, including many different families of flowering plants of varying growth forms, from herbaceous plants to trees. Hyperaccumulators absorb metals they do not need for their own nutrition. The metals are accumulated in the leaf and stem vacuoles, and to a lesser extent in the roots.

  9. Advanced neutron absorber materials

    DOEpatents

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  10. Multispectral metamaterial absorber.

    PubMed

    Grant, J; McCrindle, I J H; Li, C; Cumming, D R S

    2014-03-01

    We present the simulation, implementation, and measurement of a multispectral metamaterial absorber (MSMMA) and show that we can realize a simple absorber structure that operates in the mid-IR and terahertz (THz) bands. By embedding an IR metamaterial absorber layer into a standard THz metamaterial absorber stack, a narrowband resonance is induced at a wavelength of 4.3 μm. This resonance is in addition to the THz metamaterial absorption resonance at 109 μm (2.75 THz). We demonstrate the inherent scalability and versatility of our MSMMA by describing a second device whereby the MM-induced IR absorption peak frequency is tuned by varying the IR absorber geometry. Such a MSMMA could be coupled with a suitable sensor and formed into a focal plane array, enabling multispectral imaging. PMID:24690713

  11. Using a refrigerant leak detector to monitor waste gases from halogenated anesthetics.

    PubMed

    Rasmussen, Henrik; Thorud, Syvert

    2007-09-01

    Although halogenated gas anesthetics are indispensable in laboratory animal medicine, they are hazardous when present in the working environment. A simple technique of real-time leak detection and environmental spot monitoring can provide valuable adjunct information to current techniques of time-weighted monitoring. We investigated the minimal limit of detection of halothane, isoflurane, sevoflurane, and desflurane of a leak detector for halogenated gas refrigerants which provides a qualitative response only. We connected a container to an infrared gas analyzer to create a 135-l closed-circuit system and injected liquid halothane, isoflurane, sevoflurane, and desflurane to create calculated gas concentrations of 0.7 to 3.4 parts per million (ppm). The infrared absorbance and response of the leak detector were recorded, and a total of 5 measurements were made per concentration. The actual gas concentrations were calculated by comparison with the agent-specific absorbance standard curve. The leak detector clearly and consistently responded to halothane, isoflurane, sevoflurane, and desflurane from minimal concentrations of 2.1 +/- 0.2, 1.4 +/- 0.04, 0.8 +/- 0.04, and 1.2 +/- 0.4 ppm, respectively, as determined by infrared analysis. Although the detector does not provide numerical and time-weighted results, leak testing of equipment and repeated monitoring of the environment (spot monitoring) can provide valuable real-time information. In addition, with appropriate consideration of the methodological limitations, spot monitoring can be used to predict the likelihood of compliance with time-weighted exposure recommendations. A leak detector therefore represents a simple, effective, and inexpensive instrument for monitoring the leakage of halogenated anesthetic gases from equipment and into the working environment. PMID:17877331

  12. Copper-Catalyzed Aza-Diels-Alder Reaction and Halogenation: An Approach To Synthesize 7-Halogenated Chromenoquinolines.

    PubMed

    Yu, Xiaoqiang; Wang, Jiao; Xu, Zhanwei; Yamamoto, Yoshinori; Bao, Ming

    2016-05-20

    A new halogenation method to construct halogen-substituted quinoline moieties is described. The Cu-catalyzed intramolecular aza-Diels-Alder reaction and halogenation reaction proceeded smoothly under mild conditions to produce the corresponding 7-chloro-6H-chromeno[4,3-b]quinolines and 7-chloro-6H-thiochromeno[4,3-b]quinolines in satisfactory yields. PMID:27145113

  13. Predictive Models for Halogen-bond Basicity of Binding Sites of Polyfunctional Molecules.

    PubMed

    Glavatskikh, Marta; Madzhidov, Timur; Solov'ev, Vitaly; Marcou, Gilles; Horvath, Dragos; Graton, Jérôme; Le Questel, Jean-Yves; Varnek, Alexandre

    2016-02-01

    Halogen bonding (XB) strength assesses the ability of an electron-enriched group to be involved in complexes with polarizable electrophilic halogenated or diatomic halogen molecules. Here, we report QSPR models of XB of particular relevance for an efficient screening of large sets of compounds. The basicity is described by pKBI2 , the decimal logarithm of the experimental 1 : 1 (B : I2 ) complexation constant K of organic compounds (B) with diiodine (I2 ) as a reference halogen-bond donor in alkanes at 298 K. Modeling involved ISIDA fragment descriptors, using SVM and MLR methods on a set of 598 organic compounds. Developed models were then challenged to make predictions for an external test set of 11 polyfunctional compounds for which unambiguous assignment of the measured effective complexation constant to specific groups out of the putative acceptor sites is not granted. At this stage, developed models were used to predict pKBI2 of all putative acceptor sites, followed by an estimation of the predicted effective complexation constant using the ChemEqui program. The best consensus models perform well both in cross-validation (root mean squared error RMSE=0.39-0.47 logKBI2 units) and external predictions (RMSE=0.49). The SVM models are implemented on our website (http://infochim.u-strasbg.fr/webserv/VSEngine.html) together with the estimation of their applicability domain and an automatic detection of potential halogen-bond acceptor atoms. PMID:27491792

  14. Oxidation of hydrogen halides to elemental halogens with catalytic molten salt mixtures

    DOEpatents

    Rohrmann, Charles A.

    1978-01-01

    A process for oxidizing hydrogen halides by means of a catalytically active molten salt is disclosed. The subject hydrogen halide is contacted with a molten salt containing an oxygen compound of vanadium and alkali metal sulfates and pyrosulfates to produce an effluent gas stream rich in the elemental halogen. The reduced vanadium which remains after this contacting is regenerated to the active higher valence state by contacting the spent molten salt with a stream of oxygen-bearing gas.

  15. Internal absorber solar collector

    DOEpatents

    Sletten, Carlyle J.; Herskovitz, Sheldon B.; Holt, F. S.; Sletten, E. J.

    1981-01-01

    Thin solar collecting panels are described made from arrays of small rod collectors consisting of a refracting dielectric rod lens with an absorber imbedded within it and a reflecting mirror coated on the back side of the dielectric rod. Non-tracking collector panels on vertical walls or roof tops receive approximately 90% of solar radiation within an acceptance zone 60.degree. in elevation angle by 120.degree. or more in the azimuth sectors with a collector concentration ratio of approximately 3.0. Miniaturized construction of the circular dielectric rods with internal absorbers reduces the weight per area of glass, plastic and metal used in the collector panels. No external parts or insulation are needed as heat losses are low due to partial vacuum or low conductivity gas surrounding heated portions of the collector. The miniature internal absorbers are generally made of solid copper with black selective surface and the collected solar heat is extracted at the collector ends by thermal conductivity along the absorber rods. Heat is removed from end fittings by use of liquid circulants. Several alternate constructions are provided for simplifying collector panel fabrication and for preventing the thermal expansion and contraction of the heated absorber or circulant tubes from damaging vacuum seals. In a modified version of the internal absorber collector, oil with temperature dependent viscosity is pumped through a segmented absorber which is now composed of closely spaced insulated metal tubes. In this way the circulant is automatically diverted through heated portions of the absorber giving higher collector concentration ratios than theoretically possible for an unsegmented absorber.

  16. 40 CFR 65.154 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... subject to regulations in 40 CFR parts 264 through 266 that have required a determination of the liquid to... which it is part, as specified in 40 CFR 63.100(k) (if the referencing subpart is 40 CFR part 63... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Halogen scrubbers and other...

  17. 40 CFR 65.154 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... subject to regulations in 40 CFR parts 264 through 266 that have required a determination of the liquid to... which it is part, as specified in 40 CFR 63.100(k) (if the referencing subpart is 40 CFR part 63... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Halogen scrubbers and other...

  18. 40 CFR 65.154 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... subject to regulations in 40 CFR parts 264 through 266 that have required a determination of the liquid to... which it is part, as specified in 40 CFR 63.100(k) (if the referencing subpart is 40 CFR part 63... 40 Protection of Environment 16 2014-07-01 2014-07-01 false Halogen scrubbers and other...

  19. 40 CFR 65.154 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... subject to regulations in 40 CFR parts 264 through 266 that have required a determination of the liquid to... which it is part, as specified in 40 CFR 63.100(k) (if the referencing subpart is 40 CFR part 63... 40 Protection of Environment 16 2013-07-01 2013-07-01 false Halogen scrubbers and other...

  20. 40 CFR 65.154 - Halogen scrubbers and other halogen reduction devices.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... subject to regulations in 40 CFR parts 264 through 266 that have required a determination of the liquid to... which it is part, as specified in 40 CFR 63.100(k) (if the referencing subpart is 40 CFR part 63... 40 Protection of Environment 16 2012-07-01 2012-07-01 false Halogen scrubbers and other...

  1. Metal shearing energy absorber

    NASA Technical Reports Server (NTRS)

    Fay, R. J.; Wittrock, E. P. (Inventor)

    1973-01-01

    A metal shearing energy absorber is described. The absorber is composed of a flat thin strip of metal which is pulled through a slot in a cutter member of a metal, harder than the metal of the strip. The slot's length, in the direction perpendicular to the pull direction, is less than the strip's width so that as the strip is pulled through the slot, its edges are sheared off, thereby absorbing some of the pulling energy. In one embodiment the cutter member is a flat plate of steel, while in another embodiment the cutter member is U-shaped with the slot at its base.

  2. Lipid-absorbing Polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.; Wallace, C. J.

    1973-01-01

    The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

  3. Review of Rate Constants and Exploration of Correlations of the Halogen Transfer Reaction of Tri-substituted Carbon-centered Radicals with Molecular Halogens

    SciTech Connect

    Poutsma, Marvin L

    2012-01-01

    Rate constants for the reaction (R 3C + X2 R 3CX + X ; X = F, Cl, Br, and I) are reviewed. Because of curved Arrhenius plots and negative EX values, empirical structure-reactivity correlations are sought for log kX,298 rather than EX. The well-known poor correlation with measures of reaction enthalpy is demonstrated. The best quantitative predictor for R 3C is p, the sum of the Hammett p constants for the three substituents, R . Electronegative substituents with lone pairs, such as halogen or oxygen, thus appear to destabilize the formation of a polarized pre-reaction complex and/or TS ( +R---X---X -) by -inductive/field electron withdrawal while simultaneously stabilizing them by -resonance electron donation. The best quantitative predictor of the reactivity order of the halogens, I2 > Br2 >> Cl2 F2, is the polarizability of the halogen, (X-X). For the data set of 60 rate constants which span 6.5 orders of magnitude, a modestly successful correlation of log kX,298 is achieved with only two parameters, p and (X-X), with a mean unsigned deviation of 0.59 log units. How much of this residual variance is the result of inaccuracies in the data compared with over-simplification of the correlation approach remains to be seen.

  4. FIELD SCREENING FOR HALOGENATED VOLATILE ORGANIC COMPOUNDS

    SciTech Connect

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

    2003-07-01

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

  5. Retrieval Algorithms for the Halogen Occultation Experiment

    NASA Technical Reports Server (NTRS)

    Thompson, Robert E.; Gordley, Larry L.

    2009-01-01

    The Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) provided high quality measurements of key middle atmosphere constituents, aerosol characteristics, and temperature for 14 years (1991-2005). This report is an outline of the Level 2 retrieval algorithms, and it also describes the great care that was taken in characterizing the instrument prior to launch and throughout its mission life. It represents an historical record of the techniques used to analyze the data and of the steps that must be considered for the development of a similar experiment for future satellite missions.

  6. Degradation of halogenated carbons in alkaline alcohol

    NASA Astrophysics Data System (ADS)

    Nakagawa, Seiko; Shimokawa, Toshinari

    2002-02-01

    1,1,2-Trichloro-trifluoroethane, 1,2-dibromo-tetrafluoroethane, 2,3,4,6-tetrachlorophenol, 1,2,4-trichlorobenzene, and 2,4,6-trichloroanisole were dissolved in alkaline isopropyl alcohol and irradiated with 60Co gamma rays after purged with pure nitrogen gas. The concentration of the hydroxide ions and the parent molecules decreased with the dose, while that of the halide ions and the organic products, with less halogen atoms than the parent, increased. Chain degradation will occur in alkaline isopropyl alcohol.

  7. 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.

  8. Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants

    NASA Astrophysics Data System (ADS)

    Yoshida, Suguru; Fujita, Yasunobu

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

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

    DOEpatents

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

    1982-03-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

    Reactive halogen species (RHS), such as X·, X2 and HOX containing X = chlorine and/or bromine, are released by various sources like photo-activated sea-salt aerosol or from salt pans, and salt lakes. Despite many studies of RHS reactions, the potential of RHS reacting with secondary organic aerosol (SOA) and organic aerosol derived from biomass-burning (BBOA) has been neglected. Such reactions can constitute sources of gaseous organohalogen compounds or halogenated organic matter in the tropospheric boundary layer and can influence physicochemical properties of atmospheric aerosols. Model SOA from α-pinene, catechol, and guaiacol was used to study heterogeneous interactions with RHS. Particles were exposed to molecular chlorine and bromine in an aerosol smog-chamber in the presence of UV/VIS irradiation and to RHS, released from simulated natural halogen sources like salt pans. Subsequently, the aerosol was characterized in detail using a variety of physicochemical and spectroscopic methods. Fundamental features were correlated with heterogeneous halogenation, which results in new functional groups (FTIR spectroscopy), changes UV/VIS absorption, chemical composition (ultrahigh resolution mass spectroscopy (ICR-FT/MS)), or aerosol size distribution. However, the halogen release mechanisms were also found to be affected by the presence of organic aerosol. Those interaction processes, changing chemical and physical properties of the aerosol are likely to influence e.g. the ability of the aerosol to act as cloud condensation nuclei, its potential to adsorb other gases with low-volatility, or its contribution to radiative forcing and ultimately the Earth's radiation balance.

  11. [Possibility of using halogen lamps in surgical light sources].

    PubMed

    Mel'kin, A A; Kopli, V A

    1980-01-01

    For higher efficiency of surgical light-sources the halogen lamps are recommended for them instead of incandescent lamps. First experimental results indicated the following advantages of halogen lamps: lesser consumption of electrical power per unit of illumination, prolonged service term, and lower temperature of operative field. PMID:7402019

  12. 40 CFR 721.10015 - Halogenated benzimidazole (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halogenated benzimidazole (generic... Specific Chemical Substances § 721.10015 Halogenated benzimidazole (generic). (a) Chemical substance and... benzimidazole (PMN P-01-110) is subject to reporting under this section for the significant new uses...

  13. Field-Reversal Source for Negative Halogen Ions

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Orient, O. J.; Aladzhadzhyan, S. H.

    1987-01-01

    Large zero-energy electron-attachment cross sections result in intense ion beams. Concept for producing negative halogen ions takes advantage of large cross sections at zero kinetic energy for dissociative attachment of electrons to such halogen-containing gases as SF6, CFCI3, and CCI4.

  14. 40 CFR 721.8700 - Halogenated alkyl pyridine.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halogenated alkyl pyridine. 721.8700 Section 721.8700 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.8700 Halogenated alkyl...

  15. 40 CFR 721.3480 - Halogenated biphenyl glycidyl ethers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halogenated biphenyl glycidyl ethers... Substances § 721.3480 Halogenated biphenyl glycidyl ethers. (a) Chemical substance and significant new uses... ethers (PMNs P-90-1844, P-90-1845, and P-90-1846) are subject to reporting under this section for...

  16. 40 CFR 721.3480 - Halogenated biphenyl glycidyl ethers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Halogenated biphenyl glycidyl ethers... Substances § 721.3480 Halogenated biphenyl glycidyl ethers. (a) Chemical substance and significant new uses... ethers (PMNs P-90-1844, P-90-1845, and P-90-1846) are subject to reporting under this section for...

  17. 40 CFR 721.4484 - Halogenated indane (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Halogenated indane (generic name). 721.4484 Section 721.4484 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.4484 Halogenated indane (generic name). (a) Chemical substance and significant new...

  18. 40 CFR 721.4484 - Halogenated indane (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Halogenated indane (generic name). 721.4484 Section 721.4484 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.4484 Halogenated indane (generic name). (a) Chemical substance and significant new...

  19. 40 CFR 721.4484 - Halogenated indane (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Halogenated indane (generic name). 721.4484 Section 721.4484 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.4484 Halogenated indane (generic name). (a) Chemical substance and significant new...

  20. 40 CFR 721.535 - Halogenated alkane (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 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 reporting. (1) The chemical substance identified generically as halogenated alkane (PMN P-01-433) is...

  1. 40 CFR 721.536 - Halogenated phenyl alkane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.536 Halogenated phenyl alkane. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as halogenated phenyl alkane (PMN P-89-867)...

  2. 40 CFR 721.535 - Halogenated alkane (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 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 reporting. (1) The chemical substance identified generically as halogenated alkane (PMN P-01-433) is...

  3. 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.

  4. 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.

  5. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

  6. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

  7. Iron Chalcogenide Photovoltaic Absorbers

    SciTech Connect

    Yu, Liping; Lany, Stephan; Kykyneshi, Robert; Jieratum, Vorranutch; Ravichandran, Ram; Pelatt, Brian; Altschul, Emmeline; Platt, Heather A. S.; Wager, John F.; Keszler, Douglas A.; Zunger, Alex

    2011-08-10

    An integrated computational and experimental study of FeS₂ pyrite reveals that phase coexistence is an important factor limiting performance as a thin-film solar absorber. This phase coexistence is suppressed with the ternary materials Fe₂SiS₄ and Fe₂GeS₄, which also exhibit higher band gaps than FeS₂. Thus, the ternaries provide a new entry point for development of thin-film absorbers and high-efficiency photovoltaics.

  8. "Smart" Electromechanical Shock Absorber

    NASA Technical Reports Server (NTRS)

    Stokes, Lebarian; Glenn, Dean C.; Carroll, Monty B.

    1989-01-01

    Shock-absorbing apparatus includes electromechanical actuator and digital feedback control circuitry rather than springs and hydraulic damping as in conventional shock absorbers. Device not subject to leakage and requires little or no maintenance. Attenuator parameters adjusted in response to sensory feedback and predictive algorithms to obtain desired damping characteristic. Device programmed to decelerate slowly approaching vehicle or other large object according to prescribed damping characteristic.

  9. 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

  10. Electrochemical activation of a tetrathiafulvalene halogen bond donor in solution.

    PubMed

    Oliveira, R; Groni, S; Fave, C; Branca, M; Mavré, F; Lorcy, D; Fourmigué, M; Schöllhorn, B

    2016-06-21

    The halogen bond donor properties of iodo-tetrathiafulvalene (I-TTF) can be electrochemically switched and controlled via reversible oxidation in the solution phase. Interestingly the activation of only one single halogen bond yielded already a strong and selective interaction, quantified by cyclic voltammetry. The standard potentials of the redox couples I-TTF(0/1+) and I-TTF(1+/2+) were observed to shift upon the addition of halides. These anions selectively stabilize the cationic I-TTF species through halogen bonding in polar liquid electrolytes. The thermodynamic affinity constants for chloride and bromide binding to the oxidized species have been determined. Competition in halide binding between I-TTF(1+) and other halogen bond donors allowed for comparing the relative donor strength of the respective electrophilic species. Furthermore it has been shown that halogen bonding can prevail over hydrogen bonding in the investigated system. PMID:27231819

  11. The halogen analogs of thiolated gold nanoclusters

    SciTech Connect

    Jiang, Deen; Walter, Michael

    2012-01-01

    Is it possible to replace all the thiolates in a thiolated gold nanocluster with halogens while still maintaining the geometry and the electronic structure? In this work, we show from density functional theory that such halogen analogs of thiolated gold nanoclusters are highly likely. Using Au{sub 25}X{sub 18}{sup -} as an example, where X = F, Cl, Br, or I replaces -SR, we find that Au{sub 25}Cl{sub 18}{sup -} demonstrates a high similarity to Au{sub 25}(SR){sub 18}{sup -} by showing Au-Cl distances, Cl-Au-Cl angles, band gap, and frontier orbitals similar to those in Au{sub 25}(SR){sub 18}{sup -}. DFT-based global minimization also indicates the energetic preference of staple formation for the Au{sub 25}Cl{sub 18}{sup -} cluster. The similarity between Au{sub m}(SR){sub n} and Au{sub m}X{sub n} could be exploited to make viable Au{sub m}X{sub n} clusters and to predict structures for Au{sub m}(SR){sub n}.

  12. On The Nature of the Halogen Bond.

    PubMed

    Wang, Changwei; Danovich, David; Mo, Yirong; Shaik, Sason

    2014-09-01

    The wide-ranging applications of the halogen bond (X-bond), notably in self-assembling materials and medicinal chemistry, have placed this weak intermolecular interaction in a center of great deal of attention. There is a need to elucidate the physical nature of the halogen bond for better understanding of its similarity and differences vis-à-vis other weak intermolecular interactions, for example, hydrogen bond, as well as for developing improved force-fields to simulate nano- and biomaterials involving X-bonds. This understanding is the focus of the present study that combines the insights of a bottom-up approach based on ab initio valence bond (VB) theory and the block-localized wave function (BLW) theory that uses monomers to reconstruct the wave function of a complex. To this end and with an aim of unification, we studied the nature of X-bonds in 55 complexes using the combination of VB and BLW theories. Our conclusion is clear-cut; most of the X-bonds are held by charge transfer interactions (i.e., intermolecular hyperconjugation) as envisioned more than 60 years ago by Mulliken. This is consistent with the experimental and computational findings that X-bonds are more directional than H-bonds. Furthermore, the good linear correlation between charge transfer energies and total interaction energies partially accounts for the success of simple force fields in the simulation of large systems involving X-bonds. PMID:26588518

  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. PMID:22860296

  14. Study on the volatility of halogenated fluorenes.

    PubMed

    Oliveira, Juliana A S A; Oliveira, Tânia S M; Gaspar, Alexandra; Borges, Fernanda; Ribeiro da Silva, Maria D M C; Monte, Manuel J S

    2016-08-01

    This work reports the experimental determination of relevant thermophysical properties of five halogenated fluorenes. The vapor pressures of the compounds studied were measured at different temperatures using two different experimental techniques. The static method was used for studying 2-fluorofluorene (liquid and crystal vapor pressures between 321.04 K and 411.88 K), 2-iodofluorene (liquid and crystal vapor pressures between 362.63 K and 413.86 K), and 2,7-dichlorofluorene (crystal vapor pressures between 364.64 K and 394.22 K). The Knudsen effusion method was employed to determine the vapor pressures of 2,7-difluorofluorene (crystal vapor pressures between 299.17 K and 321.19 K), 2,7-diiodofluorene (crystal vapor pressures between 393.19 K and 415.14 K), and (again) 2-iodofluorene (crystal vapor pressures between 341.16 K and 361.12 K). The temperatures and the molar enthalpies of fusion of the five compounds were determined using differential scanning calorimetry. The application to halogenated fluorenes of recently developed methods for predicting vapor pressures and enthalpies of sublimation and vaporization of substituted benzenes is also discussed. PMID:27206270

  15. Non-Absorbable Gas Behavior in the Absorber/Evaporator of a Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Nagamoto, Wataru; Sugiyama, Takahide

    A two-dimensional numerical study on non-absorbable gas behavior in the absorber/evaporator of an absorption chiller has been performed. In the present study, the effect of the pitch-to-diameter ratio of a cylinder bundle in the absorber was highlighted. From the results, a sudden decrease of the overall heat transfer coefficient of the absorber was observed at a certain mean concentration of non-absorbable gas for each pitch-to-diameter ratio. Such a critical concentration was also found to decrease as the pitch-to- diameter ratio increased. The sudden decrease occurs due to the sudden disappearance of recirculating region, which is formed between the absorber and the evaporator, and where most of non-absorbable gas stays when it exists. As the pitch-to-diameter ratio increases, the recirculating region becomes weak because the velocity of the high velocity region supporting the recirculating flow decreases. Then, the critical mean concentration of non-absorbable gas is found to decrease as pitch-to-ratio increases.

  16. Unidirectional perfect absorber.

    PubMed

    Jin, L; Wang, P; Song, Z

    2016-01-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices. PMID:27615125

  17. 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

  18. Vibrational Spectroscopy of Halogen Substituted Benzene Derivatives

    NASA Astrophysics Data System (ADS)

    Dwivedi, Y.; Rai, S. B.

    2008-11-01

    The absorption spectra of halogen substituted benzenes have been studied in its pure form in the 400-20000 cm-1 region. Large number of bands involving fundamental, C-H overtones and combination bands has been observed. Vibrational frequencies, anharmonicity constants and dissociation energies, for the C-H stretch vibrations have been determined using local mode model. The frequencies obtained are compared with the frequencies obtained theoretically using B3LYP/6-311G* method. Effect of hydrogen atom substitution by chlorine and bromine atoms has been studied by measuring changes in the vibrational frequency and bond length of the C-H bond. Frequency changes have been well correlated with the change in charge density on the carbon as well as chlorine atoms.

  19. Halogen occultation experiment intergrated test plan

    NASA Technical Reports Server (NTRS)

    Mauldin, L. E., III; Butterfield, A. J.

    1986-01-01

    The test program plan is presented for the Halogen Occultation Experiment (HALOE) instrument, which is being developed in-house at the Langley Research Center for the Upper Atmosphere Research Satellite (UARS). This comprehensive test program was developed to demonstrate that the HALOE instrument meets its performance requirements and maintains integrity through UARS flight environments. Each component, subsystem, and system level test is described in sufficient detail to allow development of the necessary test setups and test procedures. Additionally, the management system for implementing this test program is given. The HALOE instrument is a gas correlation radiometer that measures vertical distribution of eight upper atmospheric constituents: O3, HC1, HF, NO, CH4, H2O, NO2, and CO2.

  20. 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

  1. Insights into enzymatic halogenation from computational studies

    NASA Astrophysics Data System (ADS)

    Senn, Hans

    2014-11-01

    The halogenases are a group of enzymes that have only come to the fore over the last ten years thanks to the discovery and characterization of several of novel representatives. They have re-vealed the fascinating variety of distinct chemical mechanisms that nature utilizes to activate and introduce halogens 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 stud-ies. It also seeks to identify open questions that are amenable to computational investigations. The studies discussed herein also serve to illustrate some of the limitations of the current computa-tional approaches and the challenges encountered in computational mechanistic enzymology.

  2. Long term trend of selected halogenated hydrocarbons

    NASA Technical Reports Server (NTRS)

    Borchers, R.; Gunawardena, R.; Rasmussen, R. A.

    1994-01-01

    The so-called 'Library of Background Air' at the Oregon Graduate Institute was used to determine the trend in volume mixing ratios of selected halogenated hydrocarbons in the time period 1977-1989. This library consists of background air samples most of them taken at Cape Meares (Oregon). For storage stainless steel containers are used. Tests have shown the gases under consideration to be stable in these containers. Analyses using a GC/MS-system were performed for the CFCs 11, 12, 12B1 (HALON 1211, CBrClF2), 22, 113, 114 and CH3Cl, CH3Br, CH3CCl3, CCl4. The advantage of this unique investigation: different aged air samples are analyzed at the same time with the same instrument. No calibrations or intercalibrations are needed. All data are presented in normalized mixing ratios versus time. We discuss the results, derive rate constants and present a formula to describe the nonlinear increases.

  3. Prediction of Thermodynamic Properties for Halogenated Hydrocarbon

    NASA Astrophysics Data System (ADS)

    Higashi, Yukihiro

    The predictive methods of thermodynamic properties are discussed with respect to the halogenated hydrocarbons using as working fluids for refrigeration and heat pump cycles. The methods introduced into this paper can be calculated by the limited information; critical properties, normal boiling point and acentric factor. The results of prediction are compared with the experimental values of PVT property, vapor pressure and saturated liquid density. On the basis of these comparisons, Lydersen's method for predicting the critical properties, the generalized vapor pressure correlation by Ashizawa et, al., and Hankinson-Thomson's method for predicting saturated liquid density can be recommended. With respect to the equation of state, either Soave equation or Peng-Robinson equation is effective in calculating the thermodynamic properties except high density region.

  4. Halogenated coumarin derivatives as novel seed protectants.

    PubMed

    Brooker, N; Windorski, J; Bluml, E

    2008-01-01

    Development of new and improved antifungal compounds that are target-specific is backed by a strong Federal, public and commercial mandate. Many plant-derived chemicals have proven fungicidal properties, including the coumarins (1,2-Benzopyrone) found in a variety of plants such as clover, sweet woodruff and grasses. Preliminary research has shown the coumarins to be a highly active group of molecules with a wide range of antimicrobial activity against both fungi and bacteria. It is believed that these cyclic compounds behave as natural pesticidal defence molecules for plants and they represent a starting point for the exploration of new derivative compounds possessing a range of improved antifungal activity. Within this study, derivatives of coumarin that were modified with halogenated side groups were screened for their antifungal activity against a range of soil-borne plant pathogenic fungi. Fungi included in this in vitro screen included Macrophomina phaseolina (charcoal rot), Phytophthora spp. (damping off and seedling rot), Rhizoctonia spp. (damping off and root rot) and Pythium spp. (seedling blight), four phylogenetically diverse and economically important plant pathogens. Studies indicate that these halogenated coumarin derivatives work very effectively in vitro to inhibit fungal growth and some coumarin derivatives have higher antifungal activity and stability as compared to the original coumarin compound alone. The highly active coumarin derivatives are brominated, iodinated and chlorinated compounds and results suggest that besides being highly active, very small amounts can be used to achieve LD100 rates. In addition to the in vitro fungal inhibition assays, results of polymer seed coating compatibility and phytotoxicity testing using these compounds as seed treatments will also be reported. These results support additional research in this area of natural pesticide development. PMID:19226745

  5. Reactive halogen chemistry in volcanic plumes

    NASA Astrophysics Data System (ADS)

    Bobrowski, N.; von Glasow, R.; Aiuppa, A.; Inguaggiato, S.; Louban, I.; Ibrahim, O. W.; Platt, U.

    2007-03-01

    Bromine monoxide (BrO) and sulphur dioxide (SO2) abundances as a function of the distance from the source were measured by ground-based scattered light Multiaxis Differential Optical Absorption Spectroscopy (MAX-DOAS) in the volcanic plumes of Mt. Etna on Sicily, Italy, in August-October 2004 and May 2005 and Villarica in Chile in November 2004. BrO and SO2 spatial distributions in a cross section of Mt. Etna's plume were also determined by Imaging DOAS. We observed an increase in the BrO/SO2 ratio in the plume from below the detection limit near the vent to about 4.5 × 10-4 at 19 km (Mt. Etna) and to about 1.3 × 10-4 at 3 km (Villarica) distance, respectively. Additional attempts were undertaken to evaluate the compositions of individual vents on Mt. Etna. Furthermore, we detected the halogen species ClO and OClO. This is the first time that OClO could be detected in a volcanic plume. Using calculated thermodynamic equilibrium compositions as input data for a one-dimensional photochemical model, we could reproduce the observed BrO and SO2 vertical columns in the plume and their ratio as function of distance from the volcano as well as vertical BrO and SO2 profiles across the plume with current knowledge of multiphase halogen chemistry, but only when we assumed the existence of an "effective source region," where volcanic volatiles and ambient air are mixed at about 600°C (in the proportions of 60% and 40%, respectively).

  6. Multiple-layer Radiation Absorber

    NASA Astrophysics Data System (ADS)

    Baker, Robert M. L.; Baker, Bonnie Sue

    A structure is discussed for absorbing incident radiation, either electromagnetic (EM) or sound. Such a surface structure is needed, for example, in a highly sensitive high-frequency gravitational wave or HFGW detector such as the Li-Baker. The multi-layer absorber, which is discussed, is constructed with metamaterial [MM] layer or layers on top. This MM is configured for a specific EM or sound radiation frequency band, which absorbs incident EM or sound radiation without reflection. Below these top MM layers is a substrate of conventional EM-radiation absorbing or acoustical absorbing reflective material, such as an array of pyramidal foam absorbers. Incident radiation is partially absorbed by the MM layer or layers, and then it is more absorbed by the lower absorbing and reflecting substrate. The remaining reflected radiation is even further absorbed by the MM layers on its "way out_ so that essentially all of the incident radiation is absorbed _ a nearly perfect black-body absorber. In a HFGW detector a substrate, such as foam absorbers, may outgas into a high vacuum and reduce the capability of the vacuum-producing equipment, however, the layers above this lowest substrate will seal the absorbing and reflecting substrate from any external vacuum. The layers also serve to seal the absorbing material against air or water flow past the surfaces of aircraft, watercraft or submarines. Other applications for such a multiple-level radiation absorber include stealth aircraft, missiles and submarines.

  7. Neutron Absorbing Alloys

    DOEpatents

    Mizia, Ronald E.; Shaber, Eric L.; DuPont, John N.; Robino, Charles V.; Williams, David B.

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  8. 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. PMID:27016810

  9. 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. PMID:18580948

  10. A naphthalimide-based fluorescent sensor for halogenated solvents.

    PubMed

    Dai, Li; Wu, Di; Qiao, Qinglong; Yin, Wenting; Yin, Jun; Xu, Zhaochao

    2016-02-01

    A fluorescent sensor for halogenated solvents termed AMN is reported. AMN shows strong fluorescence in most halogenated solvents (QE > 0.1) but weak fluorescence (QE<0.01) in most non-halogenated solvents. In chlorinated solvents, the fluorescence intensity decreased with the reduction of chlorine content. On the contrary, in brominated solvents the fluorescence intensity increased with the reduction of bromine content. It is worth mentioning that AMN displayed fluorescence emission centered at 520 nm in CCl4 with a quantum yield of 0.607, at 556 nm in CHCl3 with a quantum yield of 0.318, at 584 nm in CH2Cl2 with a quantum yield of 0.128, whereas in CHBr3 was centered at 441 nm with a quantum yield of 0.012. AMN was shown to have the ability to differentiate CCl4, CHCl3, CH2Cl2 and CHBr3 halogenated solvents. PMID:26691881

  11. Halogen Bonding Promotes Higher Dye-Sensitized Solar Cell Photovoltages.

    PubMed

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

    2016-08-24

    We report here an enhancement in photovoltage for dye-sensitized solar cells (DSSCs) where halogen-bonding interactions exist between a nucleophilic electrolyte species (I(-)) and a photo-oxidized dye immobilized on a TiO2 surface. The triarylamine-based dyes under investigation showed larger rate constants for dye regeneration (kreg) by the nucleophilic electrolyte species when heavier halogen substituents were positioned on the dye. The open-circuit voltages (VOC) tracked these kreg values. This analysis of a homologous series of dyes that differ only in the identity of two halogen substituents provides compelling evidence that the DSSC photovoltage is sensitive to kreg. This study also provides the first direct evidence that halogen-bonding interactions between the dye and the electrolyte can bolster DSSC performance. PMID:27518595

  12. Determination of halogens in coal after digestion using the microwave-induced combustion technique

    SciTech Connect

    Flores, E.M.M.; Mesko, M.F.; Moraes, D.P.; Pereira, J.S.F.; Mello, P.A.; Barin, J.S.; Knapp, G.

    2008-03-15

    The microwave-induced combustion (MIC) technique was applied for coal digestion and further determination of bromide, chloride, fluoride, and iodide by ion chromatography (IC). Samples (up to 500 mg) were combusted at 2 MPa of oxygen. Combustion was complete in less than 50 s, and analytes were absorbed in water or (NH{sub 4}){sub 2}CO{sub 3} solution. A reflux step was applied to improve analyte absorption. Accuracy was evaluated for Br, Cl, and F using certified reference coal and spiked samples for I. For Br, Cl, and F, the agreement was between 96 and 103% using 50 mmol L{sup -1} (NH{sub 4}){sub 2}CO{sub 3} as the absorbing solution and 5 min of reflux. With the use of the same conditions, the recoveries for I were better than 97%. Br, Cl, and I were also determined in MIC digests by inductively coupled plasma mass spectrometry, inductively coupled plasma optical emission spectrometry, and F was determined by an ion-selective electrode with agreement better than 95% to the values obtained using IC. Temperature during combustion was higher than 1350 {sup o}C, and the residual carbon content was lower than 1%. With the use of the MIC technique, up to eight samples could be processed simultaneously, and a single absorbing solution was suitable for all analytes and determination techniques (limit of detection by IC was better than 3 {mu} g g{sup -1} for all halogens).

  13. 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.

  14. 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.

  15. 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.

  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. Fluid/Melt Partition Coefficients Of Halogens In Basaltic Melt

    NASA Astrophysics Data System (ADS)

    Alletti, M.; Baker, D.; Scaillet, B.; Aiuppa, A.; Moretti, R.; Ottolini, L.

    2007-12-01

    Despite the importance of halogens (F, Cl) in volcanic degassing, solubility and fluid/melt partitioning of these elements have not been comprehensively studied in natural basaltic melts. Experimental determinations of halogen solubility in Mount Etna melts are lacking, despite this volcano being one of the most active and intensively monitored on Earth with an estimated output of thousands tonnes of halogens per day. In order to better understand halogen degassing, we present the results of a series of halogen partitioning experiments performed at different pressures (1-200 MPa), redox conditions (from Δ NNO = + 2 to Δ NNO = - 0.3) and fluid compositions. Experiments used a hawaiitic, glassy, alkaline basalt with Mg# = 0.59, sampled during the July 2001 eruption of Mount Etna. A series of experiments were conducted using H2O-NaCl or H2O-NaF solutions. The effect of CO2 in multi-component fluid H2O-CO2-NaCl or H2O-CO2-NaF was also investigated. The experimental run products were mostly glasses, but a few run products contained less than 10% crystals. The concentration of halogens in the fluid phase after the experiment was calculated from mass balance, and the partition coefficients for both Cl and F at the studied conditions determined. Using these measurements and thermodynamical models, the dependence of these partition coefficients on the fugacities of various gaseous species was investigated.

  18. Metasurface Broadband Solar Absorber

    DOE PAGESBeta

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    Here, we demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Moreover, our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributionsmore » to elucidate how the absorption occurs within the metasurface structure.« less

  19. Metasurface Broadband Solar Absorber

    PubMed Central

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

  20. Metasurface Broadband Solar Absorber

    NASA Astrophysics Data System (ADS)

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.

  1. Metasurface Broadband Solar Absorber.

    PubMed

    Azad, Abul K; Kort-Kamp, Wilton J M; Sykora, Milan; Weisse-Bernstein, Nina R; Luk, Ting S; Taylor, Antoinette J; Dalvit, Diego A R; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

  2. Ionized Absorbers in AGN

    NASA Astrophysics Data System (ADS)

    Mathur, S.

    1999-08-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  3. Ionized Absorbers in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, S.

    1999-01-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  4. 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

  5. Data for fire hazard assessment of selected non-halogenated and halogenated fire retardants: Report of Test FR 3983

    NASA Astrophysics Data System (ADS)

    Harris, R. H.; Babrauskas, V.; Levin, B. C.; Paabo, M.

    1991-10-01

    Five plastic materials, with and without fire retardants, were studied to compare the fire hazards of non-halogenated fire retardant additives with halogenated flame retardents. The plastic materials were identified by the sponsors as unsaturated polyesters, thermoplastic high density, low density and cross-linked low density polyethylenes, polypropylene, flexible and rigid poly(vinyl chlorides), and cross-linked and thermoplastic ethylene-vinyl acetate copolymers. The non-halogenated fire retardants tested were aluminum hydroxide, also known as alumina trihydrate, sodium alumino-carbonate, and magnesium hydroxide. The halogenated flame retardants were chlorine or bromine/antimony oxides. The plastics were studied using the Cone Calorimeter and the cup furnace smoke toxicity method (high density polyethylene only). The Cone Calorimeter provided data on mass consumed; time to ignition; peak rate and peak time of heat release; total heat release; effective heat of combustion; average yields of CO, CO2, HCl, and HBr; and average smoke obscuration. The concentrations of toxic gases generated in the cup furnace smoke toxicity method were used to predict the toxic potency of the mixed thermal decomposition products. The data from the Cone Calorimeter indicate that the non-halogenated fire retardants were, in most of the tested plastic formulations, more effective than the halogenated flame retardants in increasing the time to ignition. The non-halogenated fire retardants were also more effective in reducing the mass consumed, peak rate of heat release, total heat released, and effective smoke produced. The use of halogenated flame retardants increased smoke production and CO yields and, additionally, produced the known acid gases and toxic irritants, HCl and HBr, in measureable quantities.

  6. Studies of Structure and Phase Transition in [C(NH2)3]HgBr3 and [C(NH2)3]HgI3 by Means of Halogen NQR, 1H NMR, and Single Crystal X-Ray Diffraction

    NASA Astrophysics Data System (ADS)

    Terao, Hiromitsu; Hashimoto, Masao; Hashimoto, Shinichi; Furukawa, Yoshihiro

    2000-02-01

    The crystal structure of [C(NH2)3]HgBr3 was determined at room temperature: monoclinic, space group C2/c, Z = 4, a = 775.0(2), b = 1564.6(2), c = 772.7(2) pm, β = 109.12(2)°. In the crystal, almost planar HgBr3- ions are connected via Hg ··· Br bonds, resulting in single chains of trigonal bipyramidal HgBr5 units which run along the c direction. [C(NH2)3]HgI3 was found to be isomorphous with the bromide at room temperature. The temperature dependence of the halogen NQR frequencies (77 < 77K < ca. 380) and the DTA measurements evidenced no phase transition for the bromide, but a second-order phase transition at (251 ± 1) K (Tc1) and a first-order one at (210 ± 1) K for the iodide. The transitions at Tc2are accompanied with strong supercooling and significant superheating. The room temperature phase (RTP) and the intermediate temperature phase (ITP) of the iodide are characterized by two 127I(m=1/2↔3/2) NQR lines which are assigned to the terminal and the bridging I atoms, respectively. There exist three lines in the lowest temperature phase (LTP), indicating that the resonance line of the bridging atom splits into two. The signal intensities of the 127I(m =1/2↔3/2) NQR lines in the LTP decrease with decreasing temperature resulting in no detection below ca. 100 K. The 127I(m=1/2↔3/2) NQR frequency vs. temperature curves are continuous at Tcl, but they are unusual in the LTP. The T1vs. Tcurves of 1H NMR for the bromide and iodide are explainable by the reorientational motions of the cations about their pseudo three-fold axes. The estimated activation energies of the motions are 35.0 kJ/mol for the bromide, and 24.1, 30.1, and 23.0 kJ/mol for the RTP, FTP, and LTP of the iodide, respectively

  7. The halogen bond between amantadine and iodine and its application in the determination of amantadine hydrochloride in pharmaceuticals.

    PubMed

    Yan, Xiao Qing; Wang, Hui; Chen, Wei Di; Jin, Wei Jun

    2014-01-01

    It is proposed that molecular iodine as a donor could form halogen bonding complexes with amantadine (AMD) and amantadine hydrochloride (AMD-HCl) in chloroform and the resultant charge transfer bands (CT band) would be located at 259 and 253 nm, respectively. The halogen bonding interaction was explored by UV absorption, Raman and X-ray crystallography, and a new bonding model named N(+)···N(lep) bond in crystal was observed. The halogen bonding complexes were utilized in the development of simple and accurate spectrophotometry for the analysis of AMD/AMD-HCl. Compared with the traditional method based on the absorption of I3(-) at 290 and 365 nm, the new proposed spectrometry based on the CT band of halogen bonding complex was more sensitive and selective for the detection of AMD/AMD-HCl. Linear relationships with good correlation coefficients (>0.9994) were obtained between the absorbance and the AMD/AMD-HCl concentration in the range of 10-180 μg mL(-1) for AMD-HCl and 0.2-13 μg mL(-1) for AMD. The limit of detection (LOD) was 2.23 μg mL(-1) and limit of quantification (LOQ) was 7.45 μg mL(-1) for AMD-HCl. And because of the stronger bond constant between AMD and iodine than AMD-HCl, the method is more sensitive for AMD; the LOD was 0.02 μg mL(-1) and LOQ was 0.08 μg mL(-1) which was 100 times lower than that of AMD-HCl. PMID:24614731

  8. High energy decomposition of halogenated hydrocarbons

    SciTech Connect

    Mincher, B.J.; Arbon, R.E.; Meikrantz, D.H.

    1992-09-01

    This program is the INEL component of a joint collaborative effort with Lawrence Livermore National Laboratory (LLNL). Purpose is to demonstrate a viable process for breaking down hazardous halogenated organic wastes to simpler, nonhazardous wastes using high energy ionizing radiation. The INEL effort focuses on the use of spent reactor fuel gamma radiation sources to decompose complex wastes such as PCBS. Work in FY92 expanded upon that reported for FY91. During FY91 it was reported that PCBs were susceptible to radiolytic decomposition in alcoholic solution, but that only a small percentage of decomposition products could be accounted for. It was shown that decomposition was more efficient in methanol than in isopropanol and that the presence of a copper-zinc couple catalyst did not affect the reaction rate. Major goals of FY92 work were to determine the reaction mechanism, to identify further reaction products, and to select a more appropriate catalyst. Described in this report are results of mechanism specific experiments, mass balance studies, transformer oil irradiations, the use of hydrogen peroxide as a potential catalyst, and the irradiation of pure PCB crystals in the absence of diluent.

  9. Halogen Occultation Experiment (HALOE) optical filter characterization

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.

    1989-01-01

    The Halogen Occultation Experiment (HALOE) is a solar occultation experiment that will fly on the Upper Atmosphere Research Satellite to measure mixing ratio profiles of O3, H2O, NO2, NO, CH4, HCl, and HF. The inversion of the HALOE data will be critically dependent on a detailed knowledge of eight optical filters. A filter characterization program was undertaken to measure in-band transmissions, out-of-band transmissions, in-band transmission shifts with temperature, reflectivities, and age stability. Fourier Transform Infrared Spectrometers were used to perform measurements over the spectral interval 400/cm to 6300/cm (25 micrometers to 1.6 micrometers). Very high precision (0.1 percent T) in-band measurements and very high resolution (0.0001 percent T) out-of-band measurements have been made. The measurements revealed several conventional leaks at 0.01 percent transmission and greatly enhanced (1,000) leaks to the 2-element filters when placed in a Fabry-Perot cavity. Filter throughput changes by 5 percent for a 25 C change in filter temperature.

  10. Negative Halogen Ions for Fusion Applications

    SciTech Connect

    Grisham, L.R.; Kwan, J.W.; Hahto, S.K.; Hahto, S.T.; Leung, K.N.; Westenskow, G.

    2006-01-01

    Over the past quarter century, advances in hydrogen negative ion sources have extended the usable range of hydrogen isotope neutral beams to energies suitable for large magnetically confined fusion devices. Recently, drawing upon this experience, negative halogen ions have been proposed as an alternative to positive ions for heavy ion fusion drivers in inertial confinement fusion, because electron accumulation would be prevented in negative ion beams, and if desired, the beams could be photo-detached to neutrals. This paper reports the results of an experiment comparing the current density and beam emittance of Cl+ and Cl- extracted from substantially ion-ion plasmas with that of Ar+ extracted from an ordinary electron-ion plasma, all using the same source, extractor, and emittance scanner. At similar discharge conditions, the Cl- current was typically 85 – 90% of the positive chlorine current, with an e-/ Cl- ratio as low as seven without grid magnets. The Cl- was as much as 76% of the Ar+ current from a discharge with the same RF drive. The minimum normalized beam emittance and inferred ion temperatures of Cl+, Cl-, and Ar+ were all similar, so the current density and optical quality of Cl- appear as suitable for heavy ion fusion driver applications as a positive noble gas ion of similar mass. Since F, I, and Br should all behave similarly in an ion source, they should also be suitable as driver beams.

  11. Absorber for terahertz radiation management

    DOEpatents

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  12. Corrosion resistant neutron absorbing coatings

    SciTech Connect

    Choi, Jor-Shan; Farmer, Joseph C.; Lee, Chuck K.; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  13. Corrosion resistant neutron absorbing coatings

    SciTech Connect

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  14. 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

  15. 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

    2015-08-01

    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. PMID:26148182

  16. Absorber for solar power.

    PubMed

    Powell, W R

    1974-10-01

    A simple, economical absorber utilizing a new principle of operation to achieve very low reradiation losses while generating temperatures limited by material properties of quartz is described. Its performance is analyzed and indicates approximately 90% thermal efficiency and 73% conversion efficiency for an earth based unit with moderately concentrated (~tenfold) sunlight incident. It is consequently compatible with the most economic of concentrator mirrors (stamped) or mirrors deployable in space. Space applications are particularly attractive, as temperatures significantly below 300 K are possible and permit even higher conversion efficiency. PMID:20134700

  17. 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

  18. Shallow halogen vacancies in halide optoelectronic materials

    DOE PAGESBeta

    Shi, Hongliang; Du, Mao -Hua

    2014-11-05

    Halogen vacancies (VH) are usually deep color centers (F centers) in halides and can act as major electron traps or recombination centers. The deep VH contributes to the typically poor carrier transport properties in halides. However, several halides have recently emerged as excellent optoelectronic materials, e.g., CH3NH3PbI3 and TlBr. Both CH3NH3PbI3 and TlBr have been found to have shallow VH, in contrast to commonly seen deep VH in halides. In this paper, several halide optoelectronic materials, i.e., CH3NH3PbI3, CH3NH3SnI3 (photovoltaic materials), TlBr, and CsPbBr3, (gamma-ray detection materials) are studied to understand the material chemistry and structure that determine whether VHmore » is a shallow or deep defect in a halide material. It is found that crystal structure and chemistry of ns2 ions both play important roles in creating shallow VH in halides such as CH3NH3PbI3, CH3NH3SnI3, and TlBr. The key to identifying halides with shallow VH is to find the right crystal structures and compounds that suppress cation orbital hybridization at VH, such as those with long cation-cation distances and low anion coordination numbers, and those with crystal symmetry that prevents strong hybridization of cation dangling bond orbitals at VH. Furthermore, the results of this paper provide insight and guidance to identifying halides with shallow VH as good electronic and optoelectronic materials.« less

  19. Shallow halogen vacancies in halide optoelectronic materials

    NASA Astrophysics Data System (ADS)

    Shi, Hongliang; Du, Mao-Hua

    2014-11-01

    Halogen vacancies (VH ) are usually deep color centers (F centers) in halides and can act as major electron traps or recombination centers. The deep VH contributes to the typically poor carrier transport properties in halides. However, several halides have recently emerged as excellent optoelectronic materials, e.g., C H3N H3Pb I3 and TlBr. Both C H3N H3Pb I3 and TlBr have been found to have shallow VH , in contrast to commonly seen deep VH in halides. In this paper, several halide optoelectronic materials, i.e., C H3N H3Pb I3 , C H3N H3Sn I3 (photovoltaic materials), TlBr, and CsPbB r3 (gamma-ray detection materials) are studied to understand the material chemistry and structure that determine whether VH is a shallow or deep defect in a halide material. It is found that crystal structure and chemistry of n s2 ions both play important roles in creating shallow VH in halides such as C H3N H3Pb I3 , C H3N H3Sn I3 , and TlBr. The key to identifying halides with shallow VH is to find the right crystal structures and compounds that suppress cation orbital hybridization at VH , such as those with large cation-cation distances and low anion coordination numbers and those with crystal symmetry that prevents strong hybridization of cation dangling bond orbitals at VH . The results of this paper provide insight and guidance to identifying halides with shallow VH as good electronic and optoelectronic materials.

  20. The σ-hole phenomenon of halogen atoms forms the structural basis of the strong inhibitory potency of C5 halogen substituted glucopyranosyl nucleosides towards glycogen phosphorylase b.

    PubMed

    Kantsadi, Anastasia L; Hayes, Joseph M; Manta, Stella; Skamnaki, Vicky T; Kiritsis, Christos; Psarra, Anna-Maria G; Koutsogiannis, Zissis; Dimopoulou, Athina; Theofanous, Stavroula; Nikoleousakos, Nikolaos; Zoumpoulakis, Panagiotis; Kontou, Maria; Papadopoulos, George; Zographos, Spyros E; Komiotis, Dimitris; Leonidas, Demetres D

    2012-04-01

    C5 halogen substituted glucopyranosyl nucleosides (1-(β-D-glucopyranosyl)-5-X-uracil; X=Cl, Br, I) have been discovered as some of the most potent active site inhibitors of glycogen phosphorylase (GP), with respective K(i) values of 1.02, 3.27, and 1.94 μM. The ability of the halogen atom to form intermolecular electrostatic interactions through the σ-hole phenomenon rather than through steric effects alone forms the structural basis of their improved inhibitory potential relative to the unsubstituted 1-(β-D-glucopyranosyl)uracil (K(i) =12.39 μM), as revealed by X-ray crystallography and modeling calculations exploiting quantum mechanics methods. Good agreement was obtained between kinetics results and relative binding affinities calculated by QM/MM-PBSA methodology for various substitutions at C5. Ex vivo experiments demonstrated that the most potent derivative (X=Cl) toward purified GP has no cytotoxicity and moderate inhibitory potency at the cellular level. In accordance, ADMET property predictions were performed, and suggest decreased polar surface areas as a potential means of improving activity in the cell. PMID:22267166

  1. Multi-phase halogen chemistry in the tropical Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Sommariva, R.; von Glasow, R.

    2012-04-01

    We used a one-dimensional model to simulate the chemical evolution of air masses in the eastern tropical Atlantic Ocean (Cape Verde region), with a focus on halogen chemistry. The model results were compared to the observations of inorganic halogen (particularly chlorine and bromine) species made in this region. The model could reproduce the measurements of chlorine species, especially under unpolluted conditions, but it overestimated sea-salt chloride and bromine species. Agrement with the measurements could be improved by taking into account the reactivity with aldehydes and the effects of DMS and Saharan dust on aerosol pH; an hypothetical HOX -> X- aqueous-phase reaction could also improve the agreement with measured Cl2 and HOCl, particularly under semi-polluted conditions. The results showed that halogen levels and speciation are very sensitive to cloud processing, although the model could not reproduce the observations under cloudy conditions. The model results were used to calculate the impact of the observed levels of halogens: Cl accounted for 5.4 - 11.6% of total methane sinks and halogens (mostly bromine and iodine) accounted for 35 - 40% of total ozone destruction.

  2. Liquid Cryogen Absorber for MICE

    SciTech Connect

    Baynham, D.E.; Bish, P.; Bradshaw, T.W.; Cummings, M.A.; Green,M.A.; Ishimoto, S.; Ivaniouchenkov, I.; Lau, W.; Yang, S.Q.; Zisman, M.S.

    2005-08-20

    The Muon Ionization Cooling Experiment (MICE) will test ionization cooling of muons. In order to have effective ionization cooling, one must use an absorber that is made from a low-z material. The most effective low z materials for ionization cooling are hydrogen, helium, lithium hydride, lithium and beryllium, in that order. In order to measure the effect of material on cooling, several absorber materials must be used. This report describes a liquid-hydrogen absorber that is within a pair of superconducting focusing solenoids. The absorber must also be suitable for use with liquid helium. The following absorber components are discussed in this report; the absorber body, its heat exchanger, the hydrogen system, and the hydrogen safety. Absorber cooling and the thin windows are not discussed here.

  3. Dynamic vibration absorbers for vibration control within a frequency band

    NASA Astrophysics Data System (ADS)

    Yang, Cheng; Li, Deyu; Cheng, Li

    2011-04-01

    The use of dynamic vibration absorbers to control the vibration of a structure in both narrow and broadbands is discussed in this paper. As a benchmark problem, a plate incorporating multiple vibration absorbers is formulated, leading to an analytical solution when the number of absorbers yields one. Using this analytical solution, control mechanisms of the vibration absorber in different frequency bandwidths are studied; the coupling properties due to the introduction of the absorber into the host structure are analyzed; and the control performance of the absorber in different control bandwidths is examined with respect to its damping and location. It is found that the interaction between the plate and the absorber by means of the reaction force from the absorber plays a dominant role in a narrow band control, while in a relatively broadband control the dissipation by the absorber damping governs the control performance. When control bandwidth further enlarges, the optimal locations of the absorbers are not only affected by the targeted mode, but also by the other plate modes. These locations need to be determined after establishing a trade-off between the targeted mode and other modes involved in the coupling. Finally, numerical findings are assessed based on a simply-supported plate and a fair agreement between the predicted and measured results is obtained.

  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. QSARS FOR PREDICTING REDUCTIVE TRANSFORMATION RATE CONSTANTS OF HALOGENATED AROMATIC HYDROCARBONS IN ANOXIC SEDIMENT SYSTEMS

    EPA Science Inventory

    Quantitative structure-activity relationships (QSARs) are developed relating initial and final pseudo-first-order disappearance rate constants of 45 halogenated aromatic hydrocarbons in anoxic sediments to four readily available molecular descriptors: the carbon-halogen bond stre...

  6. Absorber coatings' degradation

    SciTech Connect

    Moore, S.W.

    1984-01-01

    This report is intended to document some of the Los Alamos efforts that have been carried out under the Department of Energy (DOE) Active Heating and Cooling Materials Reliability, Maintainability, and Exposure Testing program. Funding for these activities is obtained directly from DOE although they represent a variety of projects and coordination with other agencies. Major limitations to the use of solar energy are the uncertain reliability and lifetimes of solar systems. This program is aimed at determining material operating limitations, durabilities, and failure modes such that materials improvements can be made and lifetimes can be extended. Although many active and passive materials and systems are being studied at Los Alamos, this paper will concentrate on absorber coatings and degradation of these coatings.

  7. Metamaterial electromagnetic wave absorbers.

    PubMed

    Watts, Claire M; Liu, Xianliang; Padilla, Willie J

    2012-06-19

    The advent of negative index materials has spawned extensive research into metamaterials over the past decade. Metamaterials are attractive not only for their exotic electromagnetic properties, but also their promise for applications. A particular branch-the metamaterial perfect absorber (MPA)-has garnered interest due to the fact that it can achieve unity absorptivity of electromagnetic waves. Since its first experimental demonstration in 2008, the MPA has progressed significantly with designs shown across the electromagnetic spectrum, from microwave to optical. In this Progress Report we give an overview of the field and discuss a selection of examples and related applications. The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established. Insight is given into what we can expect from this rapidly expanding field and future challenges will be addressed. PMID:22627995

  8. 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.

  9. Distribution of halogens during fluid-mediated apatite replacement

    NASA Astrophysics Data System (ADS)

    Kusebauch, Christof; John, Timm; Whitehouse, Martin J.

    2016-04-01

    Apatite (Ca5(PO4)3(F,Cl,OH)) is one the most abundant halogen containing minerals in the crust. It is present in many different rock types and stable up to P-T conditions of the mantle. Although probably not relevant for the halogen budget of the mantle, apatite is potentially a carrier phase of halogens into the mantle via subduction processes and therefore important for the global halogen cycle. Different partitioning behavior of the halogens between apatite and melt/fluids causes fractionation of these elements. In hydrothermal environments apatite reacts via a coupled dissolution-reprecipitation process that leads to apatite halogen compositions which are in (local) equilibrium with the hydrothermal fluid. This behavior enables apatite to be used as fluid probe and as a tool for tracking fluid evolution during fluid-rock interaction. Here, we present a combined experimental and field related study focused on replacement of apatite under hydrothermal conditions, to investigate the partitioning of halogens between apatite and fluids. Experiments were conducted in a cold seal pressure apparatus at 0.2 GPa and temperatures ranging from 400-700°C using halogen bearing solutions of different composition (KOH, NaF, NaCl, NaBr, NaI) to promote the replacement of Cl-apatite. The halogen composition of reacted apatite was analyzed by electron microprobe (EMPA) and secondary ion mass spectrometry (SIMS). The data was used to calculate partition coefficients of halogens between fluid and apatite. Our new partitioning data show that fluorine is the most compatible halogen followed by chlorine, bromine and iodine. Comparison between partition coefficients of the apatite-fluid system and coefficients derived in the apatite-melt system reveals values for F that are one to two orders of magnitude higher. In contrast, Cl and Br show a similar partition behavior in fluid and melt systems. Consequently, apatite that formed by fluid-rock interaction will fractionate F from Cl more

  10. Mechanochemical destruction of halogenated organic pollutants: A critical review.

    PubMed

    Cagnetta, Giovanni; Robertson, John; Huang, Jun; Zhang, Kunlun; Yu, Gang

    2016-08-01

    Many tons of intentionally produced obsolete halogenated persistent organic pollutants (POPs), are stored worldwide in stockpiles, often in an unsafe manner. These are a serious threat to the environment and to human health due to their ability to migrate and accumulate in the biosphere. New technologies, alternatives to combustion, are required to destroy these substances, hopefully to their complete mineralization. In the last 20 years mechanochemical destruction has shown potential to achieve pollutant degradation, both of the pure substances and in contaminated soils. This capability has been tested for many halogenated pollutants, with various reagents, and under different milling conditions. In the present paper, a review of the published work in this field is followed by a critique of the state of the art of POPs mechanochemical destruction and its applicability to full-scale halogenated waste treatment. PMID:27054668

  11. Halogenated graphenes: rapidly growing family of graphene derivatives.

    PubMed

    Karlický, František; Kumara Ramanatha Datta, Kasibhatta; Otyepka, Michal; Zbořil, Radek

    2013-08-27

    Graphene derivatives containing covalently bound halogens (graphene halides) represent promising two-dimensional systems having interesting physical and chemical properties. The attachment of halogen atoms to sp(2) carbons changes the hybridization state to sp(3), which has a principal impact on electronic properties and local structure of the material. The fully fluorinated graphene derivative, fluorographene (graphene fluoride, C1F1), is the thinnest insulator and the only stable stoichiometric graphene halide (C1X1). In this review, we discuss structural properties, syntheses, chemistry, stabilities, and electronic properties of fluorographene and other partially fluorinated, chlorinated, and brominated graphenes. Remarkable optical, mechanical, vibrational, thermodynamic, and conductivity properties of graphene halides are also explored as well as the properties of rare structures including multilayered fluorinated graphenes, iodine-doped graphene, and mixed graphene halides. Finally, patterned halogenation is presented as an interesting approach for generating materials with applications in the field of graphene-based electronic devices. PMID:23808482

  12. 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.

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

    PubMed

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

    2016-01-21

    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. PMID:26676958

  14. Radio-absorbing properties of nickel-containing schungite powder

    NASA Astrophysics Data System (ADS)

    Lyn'kov, L. M.; Borbot'ko, T. V.; Krishtopova, E. A.

    2009-05-01

    A nickel-containing shungite powder has been synthesized by means of chemical reduction from aqueous solutions. The chemical composition and radio-absorbing properties of this powder have been studied.

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

    NASA Astrophysics Data System (ADS)

    Parker, Kimberly M.; Mitch, William A.

    2016-05-01

    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.

  16. The role of halogen species in the troposphere.

    PubMed

    Platt, U; Hönninger, G

    2003-07-01

    While the role of reactive halogen species (e.g. Cl, Br) in the destruction of the stratospheric ozone layer is well known, their role in the troposphere was investigated only since their destructive effect on boundary layer ozone after polar sunrise became obvious. During these 'Polar Tropospheric Ozone Hole' events O(3) is completely destroyed in the lowest approximately 1000 m of the atmosphere on areas of several million square kilometres. Up to now it was assumed that these events were confined to the polar regions during springtime. However, during the last few years significant amounts of BrO and Cl-atoms were also found outside the Arctic and Antarctic boundary layer. Recently even higher BrO mixing ratios (up to 176 ppt) were detected by optical absorption spectroscopy (DOAS) in the Dead Sea basin during summer. In addition, evidence is accumulating that BrO (at levels around 1-2 ppt) is also occurring in the free troposphere at all latitudes. In contrast to the stratosphere, where halogens are released from species, which are very long lived in the troposphere, likely sources of boundary layer Br and Cl are autocatalytic oxidation of sea salt halides (the 'Bromine Explosion'), while precursors of free tropospheric BrO and coastal IO probably are short-lived organo-halogen species. At the levels suggested by the available measurements reactive halogen species have a profound effect on tropospheric chemistry: In the polar boundary layer during 'halogen events' ozone is usually completely lost within hours or days. In the free troposphere the effective O(3)-losses due to halogens could be comparable to the known photochemical O(3) destruction. Further interesting consequences include the increase of OH levels and (at low NO(X)) the decrease of the HO(2)/OH ratio in the free troposphere. PMID:12738256

  17. 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. PMID:27265247

  18. 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

  19. 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

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

    PubMed

    Parker, Kimberly M; Mitch, William A

    2016-05-24

    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 ((3)DOM*), 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 (3)DOM*, 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

  1. Non-polar halogenated natural products bioaccumulated in marine samples. II. Brominated and mixed halogenated compounds.

    PubMed

    Vetter, Walter; Jun, Wu

    2003-07-01

    Several identified and potential natural brominated bioaccumulative compounds were studied in this work. 4,6-dibromo-2-(2('),4(')-dibromo)phenoxyanisole (BC-2) previously detected in Australian marine mammals and isolated from sponges, was synthesized. Two byproducts (a tetrabromo isomer and a tribromo congener) were investigated as well. The byproducts of the synthesis were not identified in the environmental samples investigated. Previously described natural brominated compounds (BC-1, BC-2, BC-3, BC-10, BC-11, MHC-1) and anthropogenic brominated diphenyl ethers (BDE-47, BDE-99, BDE-100, BDE-154) were detected in a sample of human milk. The sample was from a woman from the Faeroe Islands who frequently consumed fish as well as whale blubber and meat. The most abundant compound originated from the natural tetrabromo phenoxyanisole BC-3 which may have a 3:1 distribution of bromine on the two phenyl units. This sample also accumulated a dibromochloroanisole, as well as a previously unknown mixed halogenated compound (MHC-X) and an unknown, most likely aromatic brominated compound. Co-elutions on a DB-5 column were found for BDE-99 and BC-11 as well as BDE-154 and the unknown brominated compound. This suggests that quantification of these two compounds has to be carried out carefully.Two samples of lower trophic level, namely Baltic cod liver and Mexican mussel tissue, were investigated as well. The cod liver samples contained BDE congeners but also abundant signals for the natural 2,3,3('),4,4('),5,5(')-heptachloro-1(')-methyl-1,2(')-bipyrrole Q1 and tribromoanisole (TBA). The mussel sample contained Q1, TBA, another halogenated anisole, BC-1, BC-2, and BC-3, as well as additional, potential natural brominated compounds in the elution range of tribromophenoxyanisoles. PMID:12738265

  2. 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.

  3. Shallow halogen vacancies in halide optoelectronic materials

    SciTech Connect

    Shi, Hongliang; Du, Mao -Hua

    2014-11-05

    Halogen vacancies (VH) are usually deep color centers (F centers) in halides and can act as major electron traps or recombination centers. The deep VH contributes to the typically poor carrier transport properties in halides. However, several halides have recently emerged as excellent optoelectronic materials, e.g., CH3NH3PbI3 and TlBr. Both CH3NH3PbI3 and TlBr have been found to have shallow VH, in contrast to commonly seen deep VH in halides. In this paper, several halide optoelectronic materials, i.e., CH3NH3PbI3, CH3NH3SnI3 (photovoltaic materials), TlBr, and CsPbBr3, (gamma-ray detection materials) are studied to understand the material chemistry and structure that determine whether VH is a shallow or deep defect in a halide material. It is found that crystal structure and chemistry of ns2 ions both play important roles in creating shallow VH in halides such as CH3NH3PbI3, CH3NH3SnI3, and TlBr. The key to identifying halides with shallow VH is to find the right crystal structures and compounds that suppress cation orbital hybridization at VH, such as those with long cation-cation distances and low anion coordination numbers, and those with crystal symmetry that prevents strong hybridization of cation dangling bond orbitals at VH. Furthermore, the results of this paper provide insight and guidance to identifying halides with shallow VH as good electronic and optoelectronic materials.

  4. On the railway track dynamics with rail vibration absorber for noise reduction

    NASA Astrophysics Data System (ADS)

    Wu, T. X.

    2008-01-01

    A promising means to increase the decay rate of vibration along the rail is using a rail absorber for noise reduction. Compound track models with the tuned rail absorber are developed for investigation of the performance of the absorber on vibration reduction. Through analysis of the track dynamics with the rail absorber some guidelines are given on selection of the types and parameters for the rail absorber. It is found that a large active mass used in the absorber is beneficial to increase the decay rate of rail vibration. The effectiveness of the piecewise continuous absorber is moderate compared with the discrete absorber installed in the middle of sleeper span or at a sleeper. The most effective installation position for the discrete absorber is in the middle of sleeper span. Over high or over low loss factor of the damping material used in the absorber may degrade the performance on vibration reduction.

  5. Specific Enzymatic Halogenation-From the Discovery of Halogenated Enzymes to Their Applications In Vitro and In Vivo.

    PubMed

    Weichold, Veit; Milbredt, Daniela; van Pée, Karl-Heinz

    2016-05-23

    During the last 20 years, focus has shifted from haloperoxidases to flavin-dependent and non-heme-iron halogenases because of their proven involvement in the biosynthesis of halogenated metabolites in different organisms and the regioselectivity of their reactions. During the first 10-12 years, the main research topics were the detection of halogenases as well as the elucidation of three-dimensional structures and reaction mechanisms. This Review mainly deals with studies on halogenating enzymes published between 2010 and 2015. It focusses on the elucidation of the involvement of halogenating enzymes in halometabolite biosynthesis, application of halogenases in in vivo and in vitro systems, in vivo modification of biosynthetic pathways in bacteria and plants, improvement of enzyme stability, broadening of substrate specificity, and the combination of biocatalysis with chemical synthesis to produce new compounds. PMID:27059664

  6. 40 CFR 721.275 - Halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 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...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 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...

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

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 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...

  9. 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...

  10. 40 CFR 721.785 - Halogenated alkane aromatic compound (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halogenated alkane aromatic compound... Specific Chemical Substances § 721.785 Halogenated alkane aromatic compound (generic name). (a) Chemical... as a halogenated alkane aromatic compound (PMN P-94-1747) is subject to reporting under this...