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Artigos de revistas sobre o assunto "Gaseous iodine":
1
Tietze, S., M. R. St J. Foreman e C. Ekberg. "Synthesis of I-131 labelled iodine species relevant during severe nuclear accidents in light water reactors". Radiochimica Acta 101, n.º 10 (outubro de 2013): 675–80. http://dx.doi.org/10.1524/ract.2013.2070.
Resumo:
Summary Methods for the small scale synthesis of I-131 labelled iodine species relevant to severe nuclear accidents in light water reactors have been developed. The introduced methods allow the synthesis of impurity free, volatile, inorganic elemental iodine and volatile, organic iodides such as methyl- and ethyl iodide, as well as butyl iodide, chloroiodomethane, allyl iodide and benzyl iodide with ease. The radioactive iodine containing products are sufficiently stable to allow their storage for later use. Due to their volatility the liquid species can be easily converted into gaseous species and thus can be used in research in liquid and gaseous phase. The primary motivation for the development of these synthesis methods is to study the behaviour of volatile iodine species under the conditions of a severe nuclear accident in a light water reactor. Thus, the chemicals involved in the synthesis are chosen in a way to not generate impurities (chlorine and organic solvents) in the products which interfere with competing reactions relevant during a severe nuclear accident. Teknopox Aqua VA epoxy paint, which is used in Swedish light water reactor containments, and its reactions with the produced iodine species are described. The synthesised iodine species undergo chemisorption on paint films. Different to elemental iodine, the organic iodides are non-reactive with copper surfaces. The sorbed iodine species are partly re-released mainly in form of organic iodides and not as elemental iodine when the exposed paint films are heat treated. The partitioning and hydrolysis behaviour of gaseous methyl- and ethyl iodide between containment gas phase and water pools is found to be similar. The methods have been designed to minimise the use of harmful materials and the production of radioactive waste.
2
Carpenter, Lucy J., Rosie J. Chance, Tomás Sherwen, Thomas J. Adams, Stephen M. Ball, Mat J. Evans, Helmke Hepach et al. "Marine iodine emissions in a changing world". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 477, n.º 2247 (março de 2021): 20200824. http://dx.doi.org/10.1098/rspa.2020.0824.
Resumo:
Iodine is a critical trace element involved in many diverse and important processes in the Earth system. The importance of iodine for human health has been known for over a century, with low iodine in the diet being linked to goitre, cretinism and neonatal death. Research over the last few decades has shown that iodine has significant impacts on tropospheric photochemistry, ultimately impacting climate by reducing the radiative forcing of ozone (O 3 ) and air quality by reducing extreme O 3 concentrations in polluted regions. Iodine is naturally present in the ocean, predominantly as aqueous iodide and iodate. The rapid reaction of sea-surface iodide with O 3 is believed to be the largest single source of gaseous iodine to the atmosphere. Due to increased anthropogenic O 3 , this release of iodine is believed to have increased dramatically over the twentieth century, by as much as a factor of 3. Uncertainties in the marine iodine distribution and global cycle are, however, major constraints in the effective prediction of how the emissions of iodine and its biogeochemical cycle may change in the future or have changed in the past. Here, we present a synthesis of recent results by our team and others which bring a fresh perspective to understanding the global iodine biogeochemical cycle. In particular, we suggest that future climate-induced oceanographic changes could result in a significant change in aqueous iodide concentrations in the surface ocean, with implications for atmospheric air quality and climate.
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Zhang, L. Y., X. L. Hou e S. Xu. "Speciation of <sup>127</sup>I and <sup>129</sup>I in atmospheric aerosols at Risø, Denmark: insight into sources of iodine isotopes and their species transformations". Atmospheric Chemistry and Physics Discussions 15, n.º 17 (15 de setembro de 2015): 25139–73. http://dx.doi.org/10.5194/acpd-15-25139-2015.
Resumo:
Abstract. Speciation analysis of iodine in aerosols is a very useful approach for understanding geochemical cycling of iodine in the atmosphere. In this study, overall iodine species, including water-soluble iodine species (iodide, iodate and water-soluble organic iodine), NaOH-soluble iodine and insoluble iodine have been determined for 129I and 127I in the aerosols collected at Risø, Denmark, between March and May 2011 (shortly after the Fukushima nuclear accident) and in December 2014. The measured concentrations of total iodine are in the range of 1.04–2.48 ng m−3 for 127I and (11.3–97.0) × 105 atoms m−3 for 129I, and 129I / 127I atomic ratios of (17.8–86.8) × 10−8. The contribution of Fukushima-derived 129I (peak value of 6.3 × 104 atoms m−3) is estimated to be negligible (less than 6 %) compared to the total 129I concentration in northern Europe. The concentrations and species of 129I and 127I in the aerosols are found to be strongly related to their sources and atmospheric pathways. Aerosols that were transported over the contaminated ocean, contained higher amounts of 129I than aerosols transported over the European continent. The high 129I concentrations of the marine aerosols are attributed to secondary emission from heavily 129I-contaminated seawater rather than primary gaseous release from nuclear reprocessing plants. Water-soluble iodine was found to be a minor fraction to total iodine for both 127I (7.8–13.7 %) and 129I (6.5–14.1 %) in ocean-derived aerosols, but accounted for 20.2–30.3 % for 127I and 25.6–29.5 % for 129I in land-derived aerosols. Iodide was the predominant form of water-soluble iodine, accounting for more than 97 % of the water-soluble iodine. NaOH-soluble iodine seems to be independent of the sources of aerosols. The significant proportion of 129I and 127I found in NaOH-soluble fractions is likely bound with organic substances. In contrast to water-soluble iodine however, the sources of air masses exerted distinct influences on insoluble iodine for both 129I and 127I, with higher values for marine air masses and lower values for terrestrial air masses.
4
Zhang, Luyuan, Xiaolin Hou e Sheng Xu. "Speciation of <sup>127</sup>I and <sup>129</sup>I in atmospheric aerosols at Risø, Denmark: insight into sources of iodine isotopes and their species transformations". Atmospheric Chemistry and Physics 16, n.º 4 (23 de fevereiro de 2016): 1971–85. http://dx.doi.org/10.5194/acp-16-1971-2016.
Resumo:
Abstract. Speciation analysis of iodine in aerosols is a very useful approach for understanding geochemical cycling of iodine in the atmosphere. In this study, overall iodine species, including water-soluble iodine species (iodide, iodate and water-soluble organic iodine), NaOH-soluble iodine, and insoluble iodine have been determined for 129I and 127I in the aerosols collected at Risø, Denmark, during March and May 2011 (shortly after the Fukushima nuclear accident) and in December 2014. The measured concentrations of total iodine are in the range of 1.04–2.48 ng m−3 for 127I and (11.3–97.0) × 105 atoms m−3 for 129I, corresponding to 129I ∕ 127I atomic ratios of (17.8–86.8) × 10−8. The contribution of Fukushima-derived 129I (peak value of 6.3 × 104 atoms m−3) is estimated to be negligible (less than 6 %) compared to the total 129I concentration in northern Europe. The concentrations and species of 129I and 127I in the aerosols are found to be strongly related to their sources and atmospheric pathways. Aerosols that were transported over the contaminated seas contained higher concentrations of 129I than aerosols transported over the European continent. The high 129I concentrations of the marine aerosols are attributed to secondary emission of marine discharged 129I in the contaminated seawater in the North Sea, North Atlantic Ocean, English Channel, Kattegat, etc., rather than direct gaseous release from the European nuclear reprocessing plants (NRPs). Water-soluble iodine was found to be a minor fraction to the total iodine for both 127I (7.8–13.7 %) and 129I (6.5–14.1 %) in ocean-derived aerosols, but accounted for 20.2–30.3 % for 127I and 25.6–29.5 % for 129I in land-derived aerosols. Iodide was the predominant form of water-soluble iodine, accounting for more than 97 % of the water-soluble iodine. NaOH-soluble iodine seems to be independent of the sources of aerosols. The significant proportion of 129I and 127I found in NaOH-soluble fractions is likely bound with organic substances. In contrast to water-soluble iodine, the sources of air masses exerted distinct influences on insoluble iodine for both 129I and 127I, with higher values for marine air masses and lower values for terrestrial air masses.
5
Smyth, Peter P. A. "Iodine, Seaweed, and the Thyroid". European Thyroid Journal 10, n.º 2 (2021): 101–8. http://dx.doi.org/10.1159/000512971.
Resumo:
<b><i>Backgound:</i></b> Even a minor iodine deficiency can result in adverse thyroidal health consequences while excess iodine intake can also result in thyroid function disorders. One source of iodine is seaweed which as a foodstuff is enjoying an increasing profile in Western countries. Apart from its potential involvement in thyroidal health, gaseous iodine released from seaweeds plays a significant role in influencing coastal climate through cloud formation. <b><i>Summary:</i></b> Sources of dietary iodine, its assessment, recommended dietary intake, and consequences of iodine excess are outlined. The benefits and possible dangers of dietary intake of iodine-rich seaweed are described. Studies linking seaweed intake to breast cancer prevalence are discussed as is the role of gaseous iodine released from seaweeds influencing weather patterns and contributing to iodine intake in coastal populations. <b><i>Key Messages:</i></b> Universal salt iodization remains the optimum method of achieving optimum iodine status. Promoting increased dietary iodine intake is recommended in young women, in early pregnancy, and in vegan and vegetarian diets. Even where iodine intake is enhanced, regular assessment of iodine status is necessary. Caution against consumption of brown seaweeds (kelps) is required as even small amounts can have antithyroid actions while product labelling may be insufficient. Gaseous iodine produced from seaweeds can have a significant effect on cloud formation and associated global warming/cooling. Increased overall iodine deposition through rainfall and apparent uptake in populations dwelling in seaweed-rich coastal regions may provide a partial natural remedy to global iodine deficits.
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Kamiji, Yu, Kaoru Onuki e Shinji Kubo. "Corrosion Resistance of Nickel-Based Alloy to Gaseous Hydrogen Iodide Decomposition Environment in Thermochemical Water-Splitting Iodine-Sulfur Process". International Journal of Chemical Engineering and Applications 9, n.º 5 (outubro de 2018): 167–70. http://dx.doi.org/10.18178/ijcea.2018.9.5.720.
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Zhou, Wanshuang, Chun Kang, Cong Yu, Zhaojie Cui e Xinbo Wang. "Direct Electrical Sensing of Iodine Gas by a Covalent Organic Framework-Based Sensor". Atmosphere 14, n.º 1 (14 de janeiro de 2023): 181. http://dx.doi.org/10.3390/atmos14010181.
Resumo:
Rapid and highly sensitive detection of iodine gaseous species is crucial as the first response in case of nuclear accidents and nuclear waste clean-up. A robust and user-friendly sensor-based technology that allows online monitoring is highly desirable. Herein, we report the success of using a covalent organic framework (AQ-COF)-based sensor for real-time iodine gas adsorption and detection by the electrochemical impedance spectroscopy (EIS) technique. The sensor exhibits a high sensitivity and a pronounced electrical response to trace amounts of iodine vapor. Gaseous iodine was readily detected with a significant change in resistance (104×) at 70 °C within 5 min exposure to air. Notably, the EIS response is quite chemoselective to iodine over other common species such as air, methanol, ethanol, and water, with a selectivity of 320, 14, 49, and 1030, respectively. A mechanical study shows that the adsorption of iodine can reduce the optical bandgap of the AQ-COF, causing the impedance to drop significantly. This study demonstrates how the adsorption enrichment effect of selective I2 adsorption by a covalent organic framework can be leveraged to create a highly selective sensor for the direct online electrical detection of radioactive gaseous toxins.
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Karlsson, Erik, Jörg Neuhausen, Robert Eichler, Alexander Aerts, Ivan I. Danilov, Alexander Vögele e Andreas Türler. "Thermochromatographic behavior of iodine in fused silica columns when evaporated from lead–bismuth eutectic". Journal of Radioanalytical and Nuclear Chemistry 326, n.º 2 (11 de outubro de 2020): 1249–58. http://dx.doi.org/10.1007/s10967-020-07420-1.
Resumo:
Abstract As a step toward licensing a lead–bismuth eutectic (LBE) based reactor design, the adsorption behavior of iodine evaporated from LBE on fused silica was examined. Using inert and reducing carrier gases, depositions with an adsorption enthalpy of − 95 to − 113 kJ mol−1 were observed. These depositions are compatible with a single species, tentatively identified as bismuth monoiodide, BiI. When introducing oxidizing conditions, multiple iodine species with higher volatility form, with adsorption enthalpies ranging from − 67 to − 86 kJ mol−1. Based on an empirical correlation one of these species was identified as monatomic iodine. This work provides fundamental understanding of the LBE/iodine gaseous chemistry and related adsorption deposition behavior.
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Barnes, Ian, Karl H. Becker e Juergen Starcke. "Fourier-transform IR spectroscopic observation of gaseous nitrosyl iodine, nitryl iodine, and iodine nitrate". Journal of Physical Chemistry 95, n.º 24 (novembro de 1991): 9736–40. http://dx.doi.org/10.1021/j100177a026.
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NAKAMURA, YUJI, MISAKO SUMIYA, SHIGEO UCHIDA e YOICHIRO OHMOMO. "Transfer of gaseous iodine to rice plants." Journal of Radiation Research 27, n.º 2 (1986): 171–82. http://dx.doi.org/10.1269/jrr.27.171.
Teses / dissertações sobre o assunto "Gaseous iodine":
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Chen, Hongwei. "Development of analytical methodologies for iodine species in gaseous and particulate phases of the coastal atmosphere". [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=976812096.
2
Leloire, Maëva. "Utilisation de matériaux poreux de type Metal-Organic Framework (MOF) pour l’adsorption de molécules gazeuses (I2, RuO4) dans le contexte d’un accident de réacteur nucléaire". Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. http://www.theses.fr/2021LILUR009.
Resumo:
Les isotopes radiotoxiques de l'iode et du ruthénium, tels que 129I, 131I, 103Ru et 106Ru, sont produits en quantité significative durant la fission nucléaire. Après un accident de réacteur nucléaire, ces éléments peuvent être rapidement disséminés dans l’environnement, sous la forme d’espèces gazeuses très volatiles comme l'iode moléculaire (I2) ou le tétraoxyde de ruthénium (RuO4). Afin de limiter la dispersion de ces produits de fission en cas d’accident, des filtres composés de matériaux poreux (zéolites ou charbon actifs) peuvent être employés. Cependant, de tels solides poreux présentent des limitations dans le contexte d'accident nucléaire. En effet, la présence d'espèces empoisonnantes (par exemple NOx, H2O, COx) peut inhiber la capture d’espèces radiotoxiques. De plus, leur relative faible porosité n’est souvent pas adaptée au bon piégeage d’espèces volumineuses comme RuO4. Sur la base de ces limites, une classe récente de matériaux poreux appelés Metal-Organic Frameworks (MOFs) pourrait s’avérer être un substitut efficace. En effet, les composés MOFs sont des matériaux hybrides cristallisés, constitués de clusters inorganiques liés les uns aux autres par des ligands organiques. Cette organisation peu dense offre une porosité importante et des surfaces spécifiques élevées (jusqu'à 7000 m2.g-1), nettement supérieurs à celles des solides poreux habituels. Bien que ces solides aient déjà montré de bonnes capacités pour la capture d’espèces radioactives, très peu de données rapportent leur efficacité pour le piégeage d’espèces gazeuses (notamment RuO4) en conditions accidentelles.Afin de renforcer nos connaissances sur les composés MOFs pour une potentielle utilisation en sureté nucléaire, ce travail de thèse s’est intéressé à leur efficacité pour la capture de I2 et RuO4 volatils dans certaines matrices poreuses modèles (type UiO-66). Nous avons mis en évidence l'importance de la fonctionnalisation du ligand espaceur et du confinement de l’iode au sein du réseau poreux. Ainsi, l’iode créé une interaction forte avec la charpente des MOFs pour former d’autres espèces iodées de type Ix-. Cette transformation a notamment été analysée par spectroscopie RAMAN.Suite à cette première étude, nous avons sélectionné le solide UiO-66_NH2 comme matériau de filtration de référence pour réaliser un essai dans l’installation EPICUR de l’IRSN. Celle-ci permet la manipulation d’iode radioactif (131I) et l’étude de son confinement au sein de la charpente poreuse en conditions accidentelles (radiation, température, vapeur d’eau). Ce travail a nécessité, en amont, d’élaborer un protocole de mise en forme, afin de produire un matériau MOF avec une granulométrie sphérique millimétrique. En parallèle, un travail sur la résistance de ce matériau sous irradiation gamma a également été entrepris, dans l’installation IRMA de l’IRSN. Cette étude a confirmé l’excellente efficacité du UiO-66_NH2 dans le contexte choisi. Enfin, le matériau UiO-66_NH2 a également été le candidat choisi pour la capture de RuO4 gazeux. Les différentes analyses (MET, RMN) ont permis de quantifier le RuO4 au sein des pores et de proposer des mécanismes réactionnels expliquant sa très bonne adsorptionThe radiotoxic isotopes of iodine and ruthenium, such as 129I, 131I, 103Ru and 106Ru, are produced in significant quantities during nuclear fission. After a nuclear accident, these elements can be rapidly disseminated in the environment, in the form of highly volatile species such as molecular iodine (I2) or ruthenium tetroxide (RuO4). In order to limit the dispersion of these fission products, in case of a nuclear accident, filters composed by porous materials (zeolites or activated carbon) can be used. However, such porous solids have limitations during a nuclear accident. Indeed, the presence of poisonous species (for example NOx, H2O, COx) can ihhibit the capture of radiotoxic species. In addition, their relatively low porosity is often not suitable for the good trapping of large species such as RuO4. Based on these limitations, a recent class of porous materials called Metal-Organic Frameworks (MOFs) could be an effective substitute. Indeed, MOFs are hybrid materials, composed of inorganic clusters linked to each other by organic ligands. This low-density organization allows high porosity and high specific surface areas (up to 7000 m2.g-1), significantly higher than those of the usual porous solids. Although MOFs have already shown good capacities for capturing radioactive species, very little data exist on their effectiveness for trapping gaseous species (especially RuO4) and under accident conditions.In order to strengthen our knowledge of MOFs for potential use in nuclear safety, this thesis work focused on the effectiveness of some model MOFs for the capture of volatile I2 and RuO4 under accident conditions. We have highlighted the importance of the organic linker functionalization and confinement of iodine in the porous matrix. Thus, iodine creates a strong interaction with the framework of MOFs to form other iodine species of type Ix-. This transformation was notably analyzed by RAMAN spectroscopy.Following this first study, we selected the compound UiO-66_NH2 as reference filtration material to be tested in an IRSN facility called EPICUR. This one allows the manipulation of radioactive iodine (isotope-131) and the study of the confinement of iodine in within the porous framework in accidental conditions (radiation, temperature, steam). This work needs, upstream, to develop a shaping process in order to produce a MOF material with a spherical millimeter particle size. In parallel, an investigation on the resistance of this material under gamma irradiation was also undertaken in IRMA facility at IRSN. This study confirmed the excellent capacity of the solid UiO-66_NH2 in the present context. Finally, UiO-66_NH2 was also the candidate of choice for the capture of gaseous RuO4. The various analyzes (TEM, NMR) made it possible to quantify the RuO4 within the pores and to propose reaction mechanisms explaining its very good capture in UiO-66_NH2
3
Kessler, Matthew D. "Copper(I) Iodide-Based Chemical Sensor Materials In Gaseous And Aqueous Media". W&M ScholarWorks, 2020. https://scholarworks.wm.edu/etd/1616444306.
Resumo:
Chemical detection is an area of great importance in the shift to more green approaches to industry. Some of the chemical species produced by assorted industries can be harmful, long lived, and challenging to differentiate. Copper(I) iodide (CuI) is a material that readily forms complexes of multiple colors, both under visible and ultraviolet (UV) light. The process of CuI reacting with dimethyl sulfide vapor to produce a color change (vapochromism) has been analyzed to propose mechanistic information about the process. Using the information obtained, a series of potential sensor materials were developed with CuI as the base. The complexes were synthesized using pyridine substituted with electron withdrawing groups to give compounds of the general form (CuI)x(X-Py)y. The various complexes were characterized using elemental analysis, single crystal X-Ray diffraction, and luminescence behavior. The complex (CuI)4(3-PyNO2)4 was particularly promising as a sensing material due to its lack of emission and weak binding characteristics. This material was tested for its performance as a sensor in aqueous media in the detection of pyridine, a common industrial pollutant.
4
Le, Breton Michael Robert. "Airborne measurements of trace gases using a Chemical Ionisation Mass Spectrometer (CIMS) onboard the FAAM BAe-146 research aircraft". Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/airborne-measurements-of-trace-gases-using-a-chemical-ionisation-mass-spectrometer-cims-onboard-the-faam-bae146-research-aircraft(84308915-6dae-46d8-acb6-f189683e3e6d).html.
Resumo:
A chemical ionisation mass spectrometer (CIMS) was developed and utilised for measurements onboard the Facility for Atmospheric Airborne Measurements (FAAM) BAe-146 aircraft. The I- ionisation scheme was implemented to detect nitric acid (HNO3), formic acid (HC(O)OH), hydrogen cyanide (HCN) and dinitrogen pentoxide (N2O5) simultaneously at a sampling frequency of 1 Hz. Sensitivities ranged from 35±6 ion counts pptv-1 s-1 for HC(O)OH to 4±0.9 ion counts pptv-1 s-1 for HCN and limits of detection from 37 ppt for HNO3 and 5 ppt for HCN. Trace gas concentrations of species such as HC(O)OH are currently under predicted in global models. In order to understand their role in controlling air quality, it is crucial that their production pathways and abundance are accurately measured and constrained. To date, airborne measurements of these trace gases have been difficult as a result of instrumental limitations on an aircraft such as limit of detection and sampling frequency. The first UK airborne measurements of HC(O)OH and HNO3 confirmed that HC(O)OH is under predicted by up to a factor of 2 in a trajectory model that implements the full Master Chemical Mechanism (MCM) and Common Representative Intermediate Scheme (CRI). The inclusion of a primary vehicle source enabled the model to reproduce the concentrations observed; verifying that direct sources are under represented. Secondary formation of HC(O)OH was observed through its correlation with HNO3 and ozone (O3), indicating a strong photochemical production source. Hydroxyl (OH) concentrations were estimated for the first time in a flight around the UK using the HC(O)OH and HNO3 measurements. A biomass burning (BB) plume identification technique is applied to data obtained from Canadian biomass fires using HCN as a marker. A 6 sigma above background approach to defining a plume resulted in a higher R2 correlating value for the normalised excess mixing ratio (NEMR) to carbon monoxide (CO) when compared to current methods in the literature. The NEMR obtained from this work; 3.76±0.02 pptv ppbv-1, lies within the range found in the literature. This NEMR is then used to calculate a global emission total for HCN of 0.92 Tg (N) yr-1 when incorporated into the global tropospheric model STOCHEM CRI. The first direct N2O5 airborne measurements on an aircraft at night are compared to indirect measurements taken by a broadband cavity enhancement absorption spectrometer. An average R2 correlation coefficient of 0.87 observed over 8 flights for 1 Hz measurements indicates the selectiveness of the I- ionisation scheme to detect N2O5 directly, without nitrate (NO3) interference.
5
Cartwright, Julia Ann. "Noble gas components in Martian meteorites". Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/noble-gas-components-in-martian-meteorites(4ed4e430-096d-43a8-964a-c367ab7b2f45).html.
Resumo:
This thesis focuses on the analysis of heavy noble gases (argon, krypton and xenon) and halogens (chlorine, bromine and iodine) in Martian meteorites. In the absence of a sample-return mission, Martian meteorite analysis is essential for establishing evidence for an active fluid system, evaluating the potential for life and understanding the formation and evolution of Mars. Noble gas analysis has multiple applications for Martian meteorite study, as described in this thesis. The noble gas isotopic signatures of Earth’s atmosphere, Martian atmosphere and Martian interior are sufficiently different that they can be distinguished through noble gas analysis. Analysis of bulk and mineral separates of shergottites showed that Martian atmospheric Xe was distributed evenly amongst samples, whilst terrestrially weathered samples contained elevated concentrations of terrestrial atmospheric Xe. Both atmospheric components were introduced by weathering. Shock redistribution is responsible for the distribution of Martian atmosphere into more retentive sites. Crustal contamination may be responsible for the presence or absence of detectable 129Xe from the Martian atmosphere. Halogen abundances can be determined as an extension of the Ar-Ar dating technique. As the halogen system on Earth acts as a tracer for important fluid related processes, Martian halogen abundances in meteorites may provide a tracer for the Martian fluid system. Analysis of bulk and mineral separates of nakhlites showed that halogens are distributed amongst minor phases and clear variation of Br/Cl and I/Cl ratios was observed amongst samples. Elevated I concentrations in low temperature releases of finds NWA 998 and MIL 03346 are consistent with terrestrial contamination. Analysis of Nakhla, (a meteorite fall), showed a trend of elevated Br/Cl and I/Cl ratios in crush and low temperature releases, consistent with Br/Cl ratios observed in Martian rocks, soils and weathering products. In contrast, high temperature releases had lower I/Cl and Br/Cl ratios, which are broadly comparable to the terrestrial mantle. This trend may represent mixing of hydrothermal fluids (low Br/Cl and I/Cl) and surface brines (high Br/Cl and I/Cl). An impact-induced hydrothermal system may provide a mechanism for mixing of both fluid types. The crystallisation ages of nakhlite meteorites were determined using the Ar-Ar dating technique. The apparent ages measured were similar to previous Ar-Ar analysis, and older than reported for other chronometers. Previously unrecognised components were observed, including evidence for a trapped hydrous fluid. This Cl-rich component showed strong correlation with 40Ar and had 40Ar/36Ar and 40Ar/129XeXS ratios consistent with Martian atmosphere. As this component was released during crush and low temperature analysis, fluid inclusions formed by percolation of brines from the Martian surface are likely hosts. Both finds showed clear evidence of a trapped component with 40Ar/36Ar ratios similar to either terrestrial atmosphere or the Martian interior. A further component observed in olivine phases had low 40Ar/36Ar ratios, and likely formed by the release of 36Ar formed by cosmic-ray spallation reactions on iron.
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Molokwane, Pulane. "Development of a code for the calculation of the release of gaseous fission products and iodine from a pebble bed modular reactor / Pulane Molokwane". Thesis, 2003. http://hdl.handle.net/10394/11311.
Resumo:
This dissertation entails the calculation of the release of gaseous fission products and iodine from the Pebble Bed modular reactor (PBMR) 400MW core under a Depressurised Loss of Forced Coolant (DLOFC), where the temperature history of fuel sphere is taken into account. The release is calculated by developing a computer code (REALESE) based on a simple coated particle failure and a gas diffusion model. The computer code calculates failure fraction, kernel release fraction, layer release, Iodine decay correction, core release fraction and other parameters pertaining to a PBMR. This source code is developed in the FORTRAN 77 programming language on a Compaq Virtual FORTRAN Development Platform. Verification of the results is done in Mathcad and the Getter code. RELEASE calculations compare very well with the MathCAD calculations with deviation from 0-5%. The effects of a number of parameters on fission product release are investigated by means of sensitivity analysis involving parameters like temperature, failure fraction and diffusion coefficient. Sensitivity analysis showed that the variation of failure fraction has the greatest effect on release fission products in a PMBR. The RELEASE results are compared with GETTER calculations in addition to the MathCAD verification. RELEASE calculations showed an expected value of 2.00x10 12 Bq whereas GETTER calculations produced an expected value of 2.13x10 12 Bq, representing a percentage deviation of 6%.Thesis (MSc. ARST) North-West University, Mafikeng campus, 2003
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Chen, Hongwei [Verfasser]. "Development of analytical methodologies for iodine species in gaseous and particulate phases of the coastal atmosphere / vorgelegt von Hongwei Chen". 2005. http://d-nb.info/976812096/34.
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Tang, Bo-Siang, e 湯博翔. "Metal-Organic Framework Composites for Adsorption of Iodine Gases Molecular and the Volatile Organic Compounds". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/uxx5dq.
Resumo:
碩士中原大學
化學研究所
107
This paper mainly uses Metal-Organic Frameworks (MOFs) for the adsorption of iodine molecular gases and volatile organic compounds. In the first part, a variety of MOFs were firstly adsorbed to the iodine molecular gas in the gas phase, and the metal-organic frameworks ZIF-8 and the polymer polyethersulfone (PES) were mixed in different proportions to prepare a Mixture-Matrix Membranes(MMMs) were used to perform adsorption removal experiments on iodine molecular gas. In the identification of the properties, powder X-ray diffraction (PXRD) was used to identify the difference in the diffraction pattern between the mixture-matrix membranes and the original metal-organic frameworks, and the field-emission scanning electron microscope (FE-SEM) was used for observating the film’s surface and side, thermogravimetric analysis to identify the thermal stability of the film. The experimental results show that the mixture-matrix membrane ZIF-8@PES with ZIF-8 crystal phase is successfully prepared, and the mixing ratio of ZIF-8 is as high as 40%wt, and the adsorption amount of 1387.6 mg/g iodine molecular gas is obtained. Nearly 60% adsorption is improved compared to the original ZIF-8 powder. The second part of the paper is mainly discusses the capture of organic volatile compounds by heat-treated MOFs. After heat treatment of MOFs in the environment of 400 °C to 550 °C, the structure is identified by powder X-ray diffraction (PXRD). The adsorption experiments of powder on VOCs were carried out. The MOFs were mixed with the polymer PAN by electrospinning and then spun. The obtained fiber composites were subjected to the capture of particulate matter (PM) and volatile organic compounds (VOCs). The experimental results show that the heat treatment MOFs have selective adsorption effects on different volatile organic compounds. For example, ZIF-8 is heat treated at 450 oC for ethyl acetate (3415.9mg/g) and tetrahydrofuran (3398.9mg/g) has an excellent adsorption effect, and after heat treatment at 500 oC, it has better adsorption effect on toluene (4714.8 mg/g) and ethanol (5147.5 mg/g). In terms of fiber composite adsorption, Membrane D also adsorbed 0.5m (PM 0.5) remove effusion up to 99.93%, and also had significant adsorption effects on toluene and ethanol, respectively 29181.8 mg/g and 12065.8 mg/ g.
Livros sobre o assunto "Gaseous iodine":
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Canada, Atomic Energy of. Scrubbing Gaseous Radioiodine: Performance of the Corona Iodine Scrubber in Laboratory and Pilot-Scale Experiments. S.l: s.n, 1986.
Capítulos de livros sobre o assunto "Gaseous iodine":
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Winkelmann, J. "Diffusion of iodine (1); tetrachloro-methane (2)". In Gases in Gases, Liquids and their Mixtures, 2032. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-49718-9_1558.
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Winkelmann, Jochen. "Diffusion coefficient of iodine in ethanol". In Diffusion in Gases, Liquids and Electrolytes, 1314. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-540-73735-3_1090.
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Winkelmann, Jochen. "Diffusion coefficient of iodine in bromobenzene". In Diffusion in Gases, Liquids and Electrolytes, 1316. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-540-73735-3_1092.
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Winkelmann, Jochen. "Diffusion coefficient of iodine in benzene". In Diffusion in Gases, Liquids and Electrolytes, 1317. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-540-73735-3_1093.
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Winkelmann, Jochen. "Diffusion coefficient of iodine in cyclohexane". In Diffusion in Gases, Liquids and Electrolytes, 1318. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-540-73735-3_1094.
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Winkelmann, Jochen. "Diffusion coefficient of iodine in hexane". In Diffusion in Gases, Liquids and Electrolytes, 1319. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-540-73735-3_1095.
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Winkelmann, Jochen. "Diffusion coefficient of iodine in toluene". In Diffusion in Gases, Liquids and Electrolytes, 1320. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-540-73735-3_1096.
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Winkelmann, Jochen. "Diffusion coefficient of iodine in heptane". In Diffusion in Gases, Liquids and Electrolytes, 1322. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-540-73735-3_1098.
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Winkelmann, Jochen. "Diffusion coefficient of iodine in octane". In Diffusion in Gases, Liquids and Electrolytes, 1323. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-540-73735-3_1099.
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Winkelmann, Jochen. "Diffusion coefficient of iodine in tetradecane". In Diffusion in Gases, Liquids and Electrolytes, 1324. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-540-73735-3_1100.
Trabalhos de conferências sobre o assunto "Gaseous iodine":
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Gouëllo, M., J. Kalilainen, P. Rantanen, T. Kärkelä e A. Auvinen. "Experimental Study of the Cadmium Effects on Iodine Transport in the Primary Circuit During Severe Nuclear Accident". In 2014 22nd International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icone22-31042.
Resumo:
In case of a severe accident in a light water reactor, iodine is one of the most important fission products in the context of reactor safety because of its significant total fuel inventory, high specific activity and radiotoxicity. Consequently, understanding its behavior under severe accident transient conditions is a major point in the optimization of the accident management and mitigation. An experimental study has been launched at VTT investigating the behavior of iodine on primary circuit surfaces during a severe nuclear accident. The paper presents results obtained from the heating of metallic cadmium and caesium iodide in a crucible at temperature below 400°C under three different atmospheres. Aerosols and gaseous species released from the reaction crucible were sampled at 150°C on filters and liquid scrubbers and analyzed with HR-ICP-MS. At first, experiments were conducted with one precursor (cadmium or caesium iodide). It was observed that cadmium is predominantly present as aerosol in all atmospheres but represents less than 1% of mass what has been recovered from the facility leaching. To the contrary, caesium iodide experiment showed that sampled iodine exists mainly as gaseous species. By comparison to one-precursor studies, a change in the behavior of element was noticed when cadmium was added to caesium iodide. Different observations let to suggest a reaction between caesium iodide and cadmium in the crucible. The reaction would lead to the formation of compound made of cadmium and iodine in condensed phase below 150°C. More gaseous iodine was found from the sampling line with Ar/H2O/H2 atmosphere than in Ar/H2O atmosphere, suggesting that the cadmium is more reactive toward iodine in hydrogen-free atmosphere.
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Ka¨rkela¨, Teemu, Joachim Holm, Ari Auvinen, Christian Ekberg, Henrik Gla¨nneskog, Unto Tapper e Riitta Zilliacus. "Gas Phase Oxidation of Elemental Iodine in Containment Conditions". In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75927.
Resumo:
The aim of the study was to verify the possible formation of iodine aerosol when gaseous iodine is exposed to radiation. The effect of oxygen, ozone and iodine concentration as well as that of radiation intensity on IOX aerosol formation was determined. Experimental evidence on kinetics of particle formation, growth and transport was gained. Experiments were carried out using EXSI facility at VTT. Gaseous iodine was produced from I2-KI-water solution and carried into the facility with N2-O2 mixture. Oxygen concentration was varied between 2–50 %-vol. Due to the production technique flow contained always some humidity. UVC lamps were used as source of ionizing radiation. Ozone concentration was also varied with an ozonator. The reactions took place in a flow furnace heated to 120°C. Reaction and aerosol kinetics were studied by varying the residence time between about 2–7 seconds. The formed particles were collected on filters, after which gaseous iodine was trapped in NaOH-water solution. The amount of iodine in filters and in trapping bottles was analysed with ICP-MS. Particle concentration and size distribution were measured online using aerosol instrumentation. Ozone concentration was measured online with FTIR. The morphology as well as the elemental composition of the particles were analysed with SEM-EDX. The conversion of gaseous iodine to aerosol particles was rapid and almost complete even with low ozone concentration. The fraction of gaseous iodine increased though with decreasing residence time. Diameter of the formed primary particles was approximately 10 nm. Particles grew by agglomeration and by surface reaction. Agglomerate size distribution was log-normal with NMD varying between 60–120 nm. Size of the agglomerates increased and number concentration decreased with increasing residence time. Agglomerate size also increased with iodine concentration. Presence of ozone promoted retention of iodine in the facility probably by surface reaction. Some iodine deposited on surfaces evaporated later and formed particles in the gas stream. According to SEM-EDX analysis, particles deposited on carbon foil contained iodine and oxygen. However, the exact speciation is not known. Particles deposited on copper grids had probably reacted to copper iodide.
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Jirásek, V., O. Špalek, M. Čenský, Ja Kodymov e I. Jakubec. "Chemical oxygen-iodine laser with instantaneous production of atomic iodine from gaseous reactants". In SPIE Proceedings, editado por Willy L. Bohn, Vladimir S. Golubev, Andrey A. Ionin e Vladislav Y. Panchenko. SPIE, 2006. http://dx.doi.org/10.1117/12.660052.
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Spalek, Otomar, Vít Jirásek, Miroslav Censký, Jarmila Kodymová e Ivo Jakubec. "COIL with Atomic Iodine Produced from Gaseous Reactants". In 36th AIAA Plasmadynamics and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2005. http://dx.doi.org/10.2514/6.2005-5170.
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Novák, O., H. Turčičová, M. Divoký, M. Smrž, J. Huynh e P. Straka. "Broadband OPCPA pumped by ultra-narrowband gaseous iodine laser". In SPIE LASE, editado por Konstantin L. Vodopyanov. SPIE, 2012. http://dx.doi.org/10.1117/12.908565.
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Weber, G., H. J. Allelein, F. Funke e T. Kanzleiter. "COCOSYS and ASTEC Analyses of Iodine Multi-Compartment Tests in the ThAI-Facility". In 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89500.
Resumo:
Post test calculations with the accident codes COCOSYS-AIM and ASTEC-IODE were performed on the iodine multi-compartment tests of the German ThAI program (Thermal hydraulics, Aerosols, Iodine). In the tests transport and adsorption/desorption behavior of gaseous I2 were measured in the 60 m3 vessel with a five-compartment configuration under severe accident conditions. The thermal hydraulic modules in COCOSYS and in the containment part of ASTEC (CPA) are nearly identical but not the iodine modules AIM and IODE. The adsorption/desorption model in AIM is based on ThAI data whereas in IODE correlations derived from laboratory-scale tests are used. A 50-zone nodalisation of the ThAI vessel was used with both codes. COCOSYS-AIM and ASTEC-IODE describe qualitatively correctly the I2 concentration differences of several orders of magnitude in periods with stratified atmosphere and the slow homogenization in a convective mixed atmosphere. However, both codes overestimate the gaseous I2 concentration at high relative humidity. The most likely reason is a slow reaction of deposited I2 to the non-volatile FeI2 on the steel surfaces, which has not been modeled sufficiently yet. Further experimental investigations in the ThAI facility are envisaged. A considering of the ThAI data in the I2 adsorption/desorption correlations may improve future ASTEC-IODE results. Nevertheless, the analyses of the large-scale ThAI iodine tests have been an important validation step for COCOSYS-AIM and ASTEC-IODE demonstrating the capability of multi-compartment I2 treatment.
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Weber, G., L. Bosland, F. Funke, G. Glowa e T. Kanzleiter. "ASTEC, COCOSYS, and LIRIC Interpretation of the Iodine Behaviour in the Large-Scale THAI Test Iod-9". In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75414.
Resumo:
The large-scale iodine test Iod-9 of the German THAI programme was jointly interpreted by means of post-test analyses within the THAI Circle of the SARNET/WP16. In this test, molecular iodine (I2) was injected into the vessel dome of the 60 m3 THAI vessel to observe the evolution of its distribution between water, gas, and surfaces. The main processes addressed in Iod-9 are (a) mass transfer of I2 between the gas and the two sumps, (b) iodine transport in the main sump when it is stratified and then mixed, and (c) I2 adsorption onto, and desorption from, the vessel walls in the presence and absence of wall condensation. The codes applied by the THAI Circle partners were ASTEC-IODE (IRSN), COCOSYS-AIM (GRS) and LIRIC (AECL). IODE and AIM are semi-empirical iodine models integrated in the lumped-parameter codes ASTEC and COCOSYS respectively. With both codes multi-compartment iodine calculations can be performed. LIRIC is a mechanistic iodine model for single stand-alone calculations. The simulation results are compared with each other and with the experimental measurements. Special issues that were encountered during this work were studied in more detail: I2 diffusion in the sump water, I2 reaction with the steel of the vessel wall in gaseous and aqueous phases, and I2 mass transfer from the gas to the sump. Iodine transport and behaviour in THAI test Iod-9 are fairly well simulated by ASTEC-IODE, COCOSYS-AIM and LIRIC in post-test calculations. The measured iodine behaviour is well understood and all measured data are found to be consistent. The very slow iodine transport within the stratified main sump was simulated with COCOSYS only, in a qualitative way. Consequently, this work highlighted the need to improve modelling of (a) the wet iodine adsorption and the washdown from the walls, (b) the I2 mass transfer between gas and sump, and (c) the I2/steel reaction in the gaseous and aqueous phases. In any case, the analysis of the large-scale iodine test Iod-9 has been an important validation step for the codes applied.
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Ou, Pingwen, Yongzheng Chen, Dongyu He e Peng Chen. "Sensitivity Analysis on Key Parameters of Severe Accident Source Term of PWR". In 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-91730.
Resumo:
Abstract The complicated severe accident phenomena in typical Pressurized Water Reactor (PWR) Generation III may have a strong influence on source term release into environment and radiological consequence. The study on sensitivity analysis is beneficial to the identification of important factors in severe accident source term analysis and the quantification of their impact. ASTEC, the integral code of severe accident analysis developed by IRSN, is used to analyze the sensitivity of key parameters of severe accident source term for typical PWR Generation III, with the simulation of safety systems and source term phenomena, in the representative sequence with fast accident progression, Large Break Loss of Coolant Accident (LBLOCA). With the consideration of the design features of typical PWR Generation III and research status of severe accident source term, the key parameters for sensitivity analysis are identified and selected based on the whole process of radionuclides release, including gaseous iodine mass release fraction from primary circuit to containment, silver iodide reaction, dose rate and pH value in sump, washing effect, etc. The sensitivity is quantified by iodine release mass to containment, which is one of the most dangerous radionuclides due to its threat to environment and human thyroid after inhalation and ingestion. The gaseous iodine mass release fraction from primary circuit to containment, silver iodide reaction and washing effect are presented in results as the major contributors to the variation of severe accident source term evaluation.
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Kodymova, Jarmila, Otomar Spalek, Miroslav Censky, Vit Jirasek e Gordon D. Hager. "Advanced COIL based on atomic iodine generation using gaseous reactants". In SPIE Proceedings, editado por Oleg B. Danilov. SPIE, 2004. http://dx.doi.org/10.1117/12.558179.
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Poss, Gerhard, Teja Kanzleiter, Friedhelm Funke, Gert Langrock, Hans-Josef Allelein, Holger Nowack e Gunter Weber. "Influence of Passive Autocatalytic Recombiners on Iodine Volatility: THAI Technical Scale Experiments". In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48692.
Resumo:
Passive Autocatalytic Recombiners (PARs) in PWR-Containments remove hydrogen released in case of a severe accident with core damage by catalytic oxidation with the oxygen of the containment atmosphere. The removal of hydrogen in autocatalytic recombiners (PARs) results in temperature levels at the catalytic surfaces up to 900 °C and leads to elevated temperatures up to several hundred degrees of the gas flowing over these surfaces. Under such operating conditions suspended CsI and other iodide particles transported with the convective gas flow through PARs can be converted into volatile iodine thus influencing the iodine source term. Even low conversion rates might lead to a significant influence on the concentration of gaseous iodine in the early phase of an accident where high CsI/I2 ratios of 100:1 or even higher can be expected. In the frame of the German national THAI programme two technical-scale experiments, AER-2 and AER-5, have been performed to investigate the conversion rates CsI → I2 occurring under realistic PAR operating conditions and beyond, and the influence of PARs on CsI aerosol parameters. An original SIEMENS (now AREVA NP) type PAR has been operated under realistic thermalhydraulic conditions. CsI aerosol has been generated by evaporating ultra pure CsI in an inductive furnace and monitored in the THAI vessel, following re-condensation, by low pressure impactors and filters. Experiments with hydrogen concentrations of up to 5 vol% H2 under normal conditions and of up to 10.5 vol% H2 in a steam-inerted atmosphere have been performed. An approved and qualified sampling and detection method has been applied to determine gas borne molecular iodine concentrations. CsI → I2 conversion rates of 3% have been observed as an upper limit under realistic thermalhydraulic conditions. The results are compared to CsI → I2 conversion rates achieved in the French RECI experiments. These experiments investigated the interaction of catalytic material and metal iodides (CsI, CdI) in a lab-scale setup showing conversion rates up to 60%. However, these experiments might deviate from representative thermochemical conditions. A comparison of THAI and RECI results — as far as appropriate concerning aerosol parameters and gas temperatures — shows conversion rates in comparable dimensions. In other cases they differ significantly. The potential contribution of an operating PAR (metal iodide interaction) to the iodine source term together with the restricted knowledge from both THAI and RECI tests, means that further investigations are required.
Relatórios de organizações sobre o assunto "Gaseous iodine":
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Delwiche, Michael, Boaz Zion, Robert BonDurant, Judith Rishpon, Ephraim Maltz e Miriam Rosenberg. Biosensors for On-Line Measurement of Reproductive Hormones and Milk Proteins to Improve Dairy Herd Management. United States Department of Agriculture, fevereiro de 2001. http://dx.doi.org/10.32747/2001.7573998.bard.
Resumo:
The original objectives of this research project were to: (1) develop immunoassays, photometric sensors, and electrochemical sensors for real-time measurement of progesterone and estradiol in milk, (2) develop biosensors for measurement of caseins in milk, and (3) integrate and adapt these sensor technologies to create an automated electronic sensing system for operation in dairy parlors during milking. The overall direction of research was not changed, although the work was expanded to include other milk components such as urea and lactose. A second generation biosensor for on-line measurement of bovine progesterone was designed and tested. Anti-progesterone antibody was coated on small disks of nitrocellulose membrane, which were inserted in the reaction chamber prior to testing, and a real-time assay was developed. The biosensor was designed using micropumps and valves under computer control, and assayed fluid volumes on the order of 1 ml. An automated sampler was designed to draw a test volume of milk from the long milk tube using a 4-way pinch valve. The system could execute a measurement cycle in about 10 min. Progesterone could be measured at concentrations low enough to distinguish luteal-phase from follicular-phase cows. The potential of the sensor to detect actual ovulatory events was compared with standard methods of estrus detection, including human observation and an activity monitor. The biosensor correctly identified all ovulatory events during its testperiod, but the variability at low progesterone concentrations triggered some false positives. Direct on-line measurement and intelligent interpretation of reproductive hormone profiles offers the potential for substantial improvement in reproductive management. A simple potentiometric method for measurement of milk protein was developed and tested. The method was based on the fact that proteins bind iodine. When proteins are added to a solution of the redox couple iodine/iodide (I-I2), the concentration of free iodine is changed and, as a consequence, the potential between two electrodes immersed in the solution is changed. The method worked well with analytical casein solutions and accurately measured concentrations of analytical caseins added to fresh milk. When tested with actual milk samples, the correlation between the sensor readings and the reference lab results (of both total proteins and casein content) was inferior to that of analytical casein. A number of different technologies were explored for the analysis of milk urea, and a manometric technique was selected for the final design. In the new sensor, urea in the sample was hydrolyzed to ammonium and carbonate by the enzyme urease, and subsequent shaking of the sample with citric acid in a sealed cell allowed urea to be estimated as a change in partial pressure of carbon dioxide. The pressure change in the cell was measured with a miniature piezoresistive pressure sensor, and effects of background dissolved gases and vapor pressures were corrected for by repeating the measurement of pressure developed in the sample without the addition of urease. Results were accurate in the physiological range of milk, the assay was faster than the typical milking period, and no toxic reagents were required. A sampling device was designed and built to passively draw milk from the long milk tube in the parlor. An electrochemical sensor for lactose was developed starting with a three-cascaded-enzyme sensor, evolving into two enzymes and CO2[Fe (CN)6] as a mediator, and then into a microflow injection system using poly-osmium modified screen-printed electrodes. The sensor was designed to serve multiple milking positions, using a manifold valve, a sampling valve, and two pumps. Disposable screen-printed electrodes with enzymatic membranes were used. The sensor was optimized for electrode coating components, flow rate, pH, and sample size, and the results correlated well (r2= 0.967) with known lactose concentrations.
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Jubin, R. T. The mass transfer dynamics of gaseous methyl-iodide adsorption by silver-exchanged sodium mordenite. Office of Scientific and Technical Information (OSTI), dezembro de 1994. http://dx.doi.org/10.2172/161458.