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Literatura académica sobre el tema "Bromine and iodine"
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Artículos de revistas sobre el tema "Bromine and iodine"
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Gilfedder, B. S., M. Petri, and H. Biester. "Iodine and bromine speciation in snow and the effect of orographically induced precipitation." Atmospheric Chemistry and Physics 7, no. 10 (2007): 2661–69. http://dx.doi.org/10.5194/acp-7-2661-2007.
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Abstract. Iodine is an essential trace element for all mammals and may also influence climate through new aerosol formation. Atmospheric bromine cycling is also important due to its well-known ozone depletion capabilities. Despite precipitation being the ultimate source of iodine in the terrestrial environment, the processes effecting its distribution, speciation and transport are relatively unknown. The aim of this study was to determine the effect of orographically induced precipitation on iodine concentrations in snow and also to quantify the inorganic and organic iodine and bromine species. Snow samples were collected over an altitude profile (~840 m) from the northern Black Forest and were analysed by ion-chromatography - inductively coupled plasma mass spectrometry (IC-ICP-MS) for iodine and bromine species and trace metals (ICP-MS). All elements and species concentrations in snow showed significant (r2>0.65) exponential decrease relationships with altitude despite the short (5 km) horizontal distance of the transect. In fact, total iodine more than halved (38 to 13 nmol/l) over the 840 m height change. The results suggest that orographic lifting and subsequent precipitation has a major influence on iodine concentrations in snow. This orographically induced removal effect may be more important than lateral distance from the ocean in determining iodine concentrations in terrestrial precipitation. The microphysical removal process was common to all elements indicating that the iodine and bromine are internally mixed within the snow crystals. We also show that organically bound iodine is the dominant iodine species in snow (61–75%), followed by iodide. Iodate was only found in two samples despite a detection limit of 0.3 nmol/l. Two unknown but most likely anionic organo-I species were also identified in IC-ICP-MS chromatograms and comprised 2–10% of the total iodine. The majority of the bromine was inorganic bromide with a max. of 32% organo-Br.
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Gilfedder, B. S., M. Petri, and H. Biester. "Iodine and Bromine speciation in snow and the effect of elevation." Atmospheric Chemistry and Physics Discussions 7, no. 1 (2007): 995–1016. http://dx.doi.org/10.5194/acpd-7-995-2007.
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Abstract. Iodine is an essential trace element for all mammals and may also influence climate through new aerosol formation. Atmospheric bromine cycling is also important due to its well-known ozone depletion capabilities. Despite precipitation being the ultimate source of iodine in the terrestrial environment, the processes effecting the distribution, speciation and transport of these elements are relatively unknown. The aim of this study was to determine the effect of orographic lifting on iodine concentrations and also quantify inorganic and organic iodine and bromine species. Snow samples were collected over an altitude profile (~800 m) from the northern Black Forest and were analysed (IC-ICP-MS) for iodine and bromine species and trace metals (ICP-MS). All elements and species showed a significant (r2>0.65) inverse relationship with altitude despite the short (5 km) horizontal distance of the transect. In fact, total iodine more than halved (38 to 13 nmol/l) over the 800 m height change. The results suggest that orographic lifting of cloud masses has a major influence on iodine levels in precipitation and is perhaps more important than lateral distances in determining iodine concentrations in terrestrial precipitation. The microphysical removal process was common to all elements. We also show that organically bound iodine is the dominant iodine species in snow (61–75%), followed by iodide. Iodate was only found in two samples despite a detection limit of 0.3 nmol/l. Two unknown but most likely anionic organo-I species were also identified in IC-ICP-MS chromatograms and comprised 2–10% of the total iodine. The majority of the bromine was inorganic bromide with a max.~of 32% organo-Br.
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Spolaor, A., P. Vallelonga, J. M. C. Plane, et al. "Halogen species record Antarctic sea ice extent over glacial-interglacial periods." Atmospheric Chemistry and Physics Discussions 13, no. 2 (2013): 3881–913. http://dx.doi.org/10.5194/acpd-13-3881-2013.
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Abstract. Sea ice is an integral part of the Earth's climate system because it affects planetary albedo, sea surface salinity, and the atmosphere-ocean exchange of reactive gases and aerosols. Bromine and iodine chemistry is active at polar sea ice margins with the occurrence of bromine explosions and the biological production of organo-iodine from sea ice algae. Satellite measurements demonstrate that concentrations of bromine oxide (BrO) and iodine oxide (IO) decrease over sea ice toward the Antarctic interior. Here we present speciation measurements of bromine and iodine in the TALDICE (TALos Dome Ice CorE) ice core (159°11' E, 72°49' S, 2315 m a.s.l.) spanning the last 215 ky. The Talos Dome ice core is located 250 km inland and is sensitive to marine air masses intruding onto the Antarctic Plateau. Talos Dome bromide (Br−) is positively correlated with temperature and negatively correlated with sodium (Na). Based on the Br−/Na seawater ratio, bromide is depleted in the ice during glacial periods and enriched during interglacial periods. Total iodine, consisting of iodide (I−) and iodate (IO3−), peaks during glacials with lower values during interglacial periods. Although IO3− is considered the most stable iodine species in the atmosphere it was only observed in the TALDICE record during glacial maxima. Sea ice dynamics are arguably the primary driver of halogen fluxes over glacial-interglacial timescales, by altering the distance between the sea ice edge and the Antarctic plateau and by altering the surface area of sea ice available to algal colonization. Based on our results we propose the use of both halogens for examining Antarctic variability of past sea ice extent.
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Spolaor, A., P. Vallelonga, J. M. C. Plane, et al. "Halogen species record Antarctic sea ice extent over glacial–interglacial periods." Atmospheric Chemistry and Physics 13, no. 13 (2013): 6623–35. http://dx.doi.org/10.5194/acp-13-6623-2013.
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Abstract. Sea ice is an integral part of the earth's climate system because it affects planetary albedo, sea-surface salinity, and the atmosphere–ocean exchange of reactive gases and aerosols. Bromine and iodine chemistry is active at polar sea ice margins with the occurrence of bromine explosions and the biological production of organoiodine from sea ice algae. Satellite measurements demonstrate that concentrations of bromine oxide (BrO) and iodine oxide (IO) decrease over sea ice toward the Antarctic interior. Here we present speciation measurements of bromine and iodine in the TALDICE (TALos Dome Ice CorE) ice core (159°11' E, 72°49' S; 2315 m a.s.l.) spanning the last 215 ky. The Talos Dome ice core is located 250 km inland and is sensitive to marine air masses intruding onto the Antarctic Plateau. Talos Dome bromide (Br−) is positively correlated with temperature and negatively correlated with sodium (Na). Based on the Br−/Na seawater ratio, bromide is depleted in the ice during glacial periods and enriched during interglacial periods. Total iodine, consisting of iodide (I−) and iodate (IO3−), peaks during glacials with lower values during interglacial periods. Although IO3− is considered the most stable iodine species in the atmosphere it was only observed in the TALDICE record during glacial maxima. Sea ice dynamics are arguably the primary driver of halogen fluxes over glacial–interglacial timescales, by altering the distance between the sea ice edge and the Antarctic plateau and by altering the surface area of sea ice available to algal colonization. Based on our results we propose the use of both halogens for examining Antarctic variability of past sea ice extent.
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Prashanth, Nagaraj, Kanakapura Basavaiah, Sameer Abdulrahman, Nagaraju Rajendraprasad, and Basavaiah Vinay. "Application of bromate-bromide mixture as a green brominating agent for the spectrophotometric determination of atenolol in pharmaceuticals." Chemical Industry and Chemical Engineering Quarterly 18, no. 1 (2012): 43–52. http://dx.doi.org/10.2298/ciceq110721045p.
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Two highly sensitive spectrophotometric methods are proposed for the quantification of atenolol (ATN) in pure drug as well as in pharmaceutical formulations. The methods are based on the bromination reaction of ATN with a known excess of bromate-bromide mixture in acid medium followed by the determination of unreacted bromine. The residual bromine is determined by its reaction with excess iodide and the liberated iodine (I3?) is either measured at 360 nm (method A) or reacted with starch followed by the measurement of the starch-iodine chromogen at 570 nm (method B). Under the optimum conditions, ATN could be assayed in the concentration ranges of 0.5-9.0 and 0.3-6.0?g mL-1 for method A and method B, respectively, with corresponding molar absorptivity values of 2.36?104 and 2.89?104 L/mol.cm. Sandell?s sensitivity values are found to be 0.0113 and 0.0092 ?g/cm2 for method A and method B, respectively. The proposed methods were successfully applied to the analysis of different commercial brands of pharmaceutical formulations and the results obtained by the proposed methods were in good agreement with those obtained using the reference method. The reliability of the methods was further ascertained by recovery studies using standard- addition method.
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Abdel-Moety, Ezzat M., Abdel-Kader S. Ahmad, and Mohie Sharaf El-Din. "Determination of Iodine Values of Lipids by Bromide Ion Selective Electrode." Journal of AOAC INTERNATIONAL 69, no. 1 (1986): 67–69. http://dx.doi.org/10.1093/jaoac/69.1.67.
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Abstract A semimicro method for determination of iodine values of lipids is described. An accurately weighed smear of sample (10-20 mg) on a strip of ashless filter paper, 14 × 40 mm, is brominated with bromine vapors for about 5 min. Excess bromine adsorbed on the filter paper is allowed to sublime. Bromine absorbed by the sample is directly related to the degree of unsaturation. Paper with brominated sample is subjected to oxygen flask combustion in the presence of 2 mL 1M sodium hydroxide solution and 10 mL water as absorbing liquid. Bromide formed, which is equivalent to unsaturation, is determined by bromide ion selective electrode. Bromide ions can be also determined by gravimetry or by indirect argentometric titration. The results were statistically analyzed. The iodine values of some fatty acids and oils, determined by this technique, are in accord with those of some officially approved methods.
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Spolaor, A., P. Vallelonga, J. Gabrieli, et al. "Seasonality of halogen deposition in polar snow and ice." Atmospheric Chemistry and Physics Discussions 14, no. 6 (2014): 8185–207. http://dx.doi.org/10.5194/acpd-14-8185-2014.
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Abstract. The atmospheric chemistry of iodine and bromine in polar regions is of interest due to the key role of halogens in many atmospheric processes, particularly tropospheric ozone destruction. Bromine is emitted from the open ocean but is enriched above first-year sea ice during springtime bromine explosion events, whereas iodine is emitted from biological communities hosted by sea ice. It has been previously demonstrated that bromine and iodine are present in Antarctic ice over glacial-interglacial cycles. Here we investigate seasonal variability of bromine and iodine in polar snow and ice, to evaluate their emission, transport and deposition in Antarctica and the Arctic and better understand potential links to sea ice. We find that bromine enrichment (relative to sea salt content) and iodine concentrations in polar ice do vary seasonally in Arctic snow and Antarctic ice and we relate such variability to satellite-based observations of tropospheric halogen concentrations. Peaks of bromine enrichment in Arctic snow and Antarctic ice occur in spring and summer, when sunlight is present. Iodine concentrations are largest in winter Antarctic ice strata, contrary to contemporary observations of summer maxima in iodine emissions.
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Rybakova, Anastasiya V., Dmitry G. Kim, Elena I. Danilina, Olesya V. Sazhaeva, Marina A. Ezhikova, and Mikhail I. Kodess. "HETEROCYCLIZATION OF 3-PROPARGYLSULFANYL-5 PHENYL-1,2,4-TRIAZINE: TANDEM REACTIONS WITH BROMINE LEADING TO NEW DERIVATIVES OF 7 PHENYL[1,3]THIAZOLO[3,2-B][1,2,4]TRIAZINIUM." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 63, no. 6 (2020): 19–24. http://dx.doi.org/10.6060/ivkkt.20206306.6102.
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Derivatives of 1,2,4-triazine-3-thione exhibit biological activity in a wide range. They have optoelectronic properties and can be used as synthons in synthesis of various pyridines by the Diels-Alder reaction. 1,2,4-Triazines are of the greatest interest, for organic synthesis in particular. In the present study we have established that the interaction of 3-propargylsulfanyl-5-phenyl-1,2,4-triazine, obtained by alkylation of 5-phenyl-2,3-dihydro-1,2,4-triazine-3-thione with 3-bromopropyne in acetone in the presence of triethylamine, with halogens leads to annelation of thiazole cycle. At that, [1,3]thiazolo[3,2-b][1,2,4]triazinium systems contain either endo- or exocyclic double bond in their structure, depending on the halogen type. By way of example, iodine acting on propargyl sulfide forms a dark precipitate of (3Z)-3-iodomethylene-7-phenyl-2,3-dihydro-[1,3]thiazolo[3,2-b][1,2,4]triazinium triiodide, the structure of which has been confirmed by 1H and 13C NMR spectroscopy, including two-dimensional 2D 1H-13C HSQC, HMBC and 1H-1H NOESY experiments. Treatment of the obtained triiodide by sodium iodide in acetone leads to synthesis of the corresponding monoiodide, which precipitates from the reaction mixture as a dark red precipitate. Reaction with bromine, as distinct from heterocyclization under iodine action, comprises an unusual cascade reaction including the stages of electrophile heterocyclization, bromine addition, and hydrogen bromide elimination, which leads to formation of 3-dibromomethyl-7-phenyl[1,3]thiazolo[3,2-b][1,2,4]triazinium bromide. It should be pointed out that the identifying feature of 3-propargylsulfanyl-5-phenyl-1,2,4-triazine heterocyclization under iodine and bromine action is the signal bias of the aromatic proton in a triazine ring towards weak field in the 1H NMR spectrum of the reaction products. This is presumably associated with formation of the positively charged nitrogen atom.
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Mityusheva, T. P., and O. Ye Amosova. "Industrial brines of the Khoreyver depression of the Pech ora plate." Vestnik of Geosciences 8 (2021): 27–45. http://dx.doi.org/10.19110/geov.2021.8.3.
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We studied areal distribution of the Khoreyver depression and strontium and lithium-rich iodine-bromine and iodine-boron industrial brines in the hydrogeological section. We presented the potential of the territory for practical use of industrial sodium chloride and calcium-sodium underground brines in the maps of distribution of bromine, iodine, boron and strontium-lithium iodinebromine and iodine-boric industrial brines within three Paleozoic calcareous aquifers (O2–S–D1; D3–C1; C–P1). Separate areas with lithium-strontium iodine - bromine and iodine-boric standard quality brines are designated.
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Spolaor, A., P. Vallelonga, J. Gabrieli, et al. "Seasonality of halogen deposition in polar snow and ice." Atmospheric Chemistry and Physics 14, no. 18 (2014): 9613–22. http://dx.doi.org/10.5194/acp-14-9613-2014.
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Abstract. The atmospheric chemistry of iodine and bromine in Polar regions is of interest due to the key role of halogens in many atmospheric processes, particularly tropospheric ozone destruction. Bromine is emitted from the open ocean but is enriched above first-year sea ice during springtime bromine explosion events, whereas iodine emission is attributed to biological communities in the open ocean and hosted by sea ice. It has been previously demonstrated that bromine and iodine are present in Antarctic ice over glacial–interglacial cycles. Here we investigate seasonal variability of bromine and iodine in polar snow and ice, to evaluate their emission, transport and deposition in Antarctica and the Arctic and better understand potential links to sea ice. We find that bromine and iodine concentrations and Br enrichment (relative to sea salt content) in polar ice do vary seasonally in Arctic snow and Antarctic ice. Although seasonal variability in halogen emission sources is recorded by satellite-based observations of tropospheric halogen concentrations, seasonal patterns observed in snowpack are likely also influenced by photolysis-driven processes. Peaks of bromine concentration and Br enrichment in Arctic snow and Antarctic ice occur in spring and summer, when sunlight is present. A secondary bromine peak, observed at the end of summer, is attributed to bromine deposition at the end of the polar day. Iodine concentrations are largest in winter Antarctic ice strata, contrary to contemporary observations of summer maxima in iodine emissions. These findings support previous observations of iodine peaks in winter snow strata attributed to the absence of sunlight-driven photolytic re-mobilisation of iodine from surface snow. Further investigation is required to confirm these proposed mechanisms explaining observations of halogens in polar snow and ice, and to evaluate the extent to which halogens may be applied as sea ice proxies.