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1
Guido-Garcia, Fabiola. "The biogeochemistry of iodine." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/the-biogeochemistry-of-iodine(031a6229-1a96-4068-9764-8291bafb0cad).html.
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Iodine-129 is a high-yield fission product of 235U and 239Pu; is produced in nuclear power plants and is therefore present in substantial quantities in radioactive wastes. In the environment, iodine exists as a range of species: iodate (IO3-), iodide (I-), elemental iodine (I2), HOI and organic species are the most common. The behaviour of iodine in the environment is linked to its speciation which can be affected by different factors such as pH, redox potential and enzymatic reduction. Previous research has shown that iodine speciation can determine its fate in the environment; however the mechanisms of redox cycling amongst the different species are not yet fully understood. This research project has focused on improving the understanding of the changes on speciation of iodine in sediment and mineral systems undergoing redox cycling reactions. The fate and changes in iodine speciation were studied under reducing and oxidising conditions, with all experiments conducted under circumneutral pH conditions. Overall the results showed that when microbial activity is promoted in a sediment system, iodate is reduced to iodide with the reduction occurring during manganese reduction. Further, when nitrate is present at high concentrations the reduction of iodate is retarded. A net release of native iodine from sediments was observed in all experiments conducted with sediments; confirming previous observations that sediment bound iodine is released from sediments under reducing conditions. Modest abiotic reduction of iodate was observed under manganese and iron reduction; and iodate reduction happened faster in a mixed system with iron and pure culture bacteria than solely by the pure culture alone or via abiotic reduction with Fe(II). When reduced experiments were exposed to air, concentrations of iodide decreased with no iodate ingrowth or losses in total iodine in solution. This suggested that iodide had been oxidised to intermediate species (I2, HOI) that were not detected, although this reaction has been described in past research. Finally, when no microbial activity is promoted, iodine remains as iodate which showed modest sorption onto sediment systems and Fe(III) oxide. Overall, these results highlight the important role that bacteria play in the reduction of iodate. This research also confirms that iodine speciation impacts on the fate of 129I throughout the environment, where it may be less mobile in an oxic environment than under reducing conditions. Moreover, some techniques of bioremediation (e.g. promoting metal reducing conditions) may cause the release of radioactive iodine to solution.
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Khan, Zulfiqar Ali. "Novel iodine mediated carbocyclisations and hypervalent iodine(III) reagents." Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/54137/.
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The first chapter focuses on the introduction of iodine mediated carbocyclisations and their applications continue to present a stimulating challenge in target- and diversity-oriented synthesis. The second chapter discusses applications and brief literature overview about classical approaches towards the syntheses of indene derivatives. Herein the syntheses of 3-iodo-1 H-indene derivatives via iodonium-promoted 5-endo-dig carbocyclisation of 2-substituted ethynylmalonates as a key starting material are described. Within this study, we were able to show that the 3-iodo-1 H-indene can be used as a synthetic platform not only for the palladium chemistry but also as a catalyst for the in situ generation of [text unavailable] hypervalent iodine reagent. Additionally, 3-iodo-1 H-indene derivatives have the potential to perform asymmetric synthesis. Third chapter demonstrates tandem iodine mediated carboannulation of the stilbene malonate derivatives via either 5-exo- or 6-endo-trig mode under basic reagents with subsequent lactonisation to structurally complex indanes and tetrahydronaphthalenes with three new stereogenic centres. In the present study, a unique stereochemistry was observed in the case of tetrahydroindenofuranones and confirmed by single crystal X-ray analysis. These cyclisations proceed exclusively with the retention of configuration to form tetrahydroindenofuranones. Both the compounds formed as a single diastereomers as judged from their 1H and 13C NMR spectrum. In fourth chapter the synthesis of novel simplified analogues of IBA by oxidation of [text unavailable] diiodoacrylic acids are described. Additionally, the ligand exchange resulted in tosylate derivative. The new reagents have been utilized in various well established oxidative transformations with superior or similar reactivity as conventional hypervalent iodine(III) reagents.
3
Untoro, Juliawati. "Use of oral iodized oil to control iodine deficiency in Indonesia /." Online version, 1999. http://bibpurl.oclc.org/web/35068.
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Mowbray, Andrew Paul. "The surface chemistry of iodine and iodine compounds on indium antimonide(001)." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334804.
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Singhania, Amit. "Studies on catalytic decomposition of hydrogen iodide for hydrogen production in thermochemical sulphur-iodine (SI) cycle." Thesis, IIT Delhi, 2016. http://localhost:8080/xmlui/handle/12345678/7084.
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Hassan, Shetaya Waleed Hares Abdou. "Iodine dynamics in soil." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12261/.
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The principal aim of this investigation was to understand the transformation and reaction kinetics of iodide and iodate added to soil in relation to soil properties. In addition, to integrate the data into a predictive model of iodide and iodate sorption kinetics parameterised by soil properties. Solid phase fractionation coupled with solution phase speciation (HPLC-ICPMS) was used to follow the assimilation of 129I- and 129IO3- spikes into ‘steady state’ soil microcosms. The extraction efficiency of tetra-methyl ammonium hydroxide (TMAH) for soil iodine, and the effects of experimental procedures and conditions on the speciation of extracted iodine were tested. Moreover, the possibility of extracting ‘reactive’ inorganic iodine forms sorbed on soil metal oxides by competition with PO43- ions was investigated. Results showed that changing TMAH concentration, extraction time, extraction temperature or soil particle size did not generally affect the concentrations of total iodine extracted. The ratio of iodide to total iodine in the TMAH extracts varied with the extraction conditions which led to the conclusion that part, or all, of the measured iodide is possibly produced by hydrolysis of organic iodine forms. This conclusion was also confirmed by the detection of high concentrations of iodide in TMAH extracts of a humic acid. Only iodide was measured in the phosphate extracts of soil and it constituted up to 33% of the total iodine in the KH2PO4 extracts which indicates that most of the iodine mobilised by KH2PO4 is organically bound. When soil / KH2PO4 suspensions were spiked with 129I- and 129IO3-, at least 50% of 129I- and 15% of 129IO3- were recoverable after 72 hours of reaction. The lowest recoveries were observed with the highest concentration of KH2PO4, which also mobilised the greatest concentrations of DOC, indicating that although KH2PO4 is capable of releasing sorbed iodide and iodate in soil, it may also promote iodide and iodate reaction with soil organic matter. Iodine content of soil biomass was determined following chloroform fumigation of soil. The concentrations of total iodine in fumigated soil samples were only marginally higher than iodine concentration in the control samples indicating that microbial biomass iodine constitutes only a small fraction of total soil iodine (0.01 – 0.25 %). The change in iodine (129I) solubility and speciation in nine soils with contrasting properties (pH, Fe/Mn oxides, organic carbon and iodine contents), incubated for nine months at 10oC and 20oC, was also investigated. The rate of 129I sorption was greater in soils with large organic carbon contents, low pH and at higher temperatures. Loss of iodide (129I-) from solution was extremely rapid, apparently reaching completion over minutes-hours; iodate (IO3-) loss from solution was slower, typically occurring over hours-days. In all soils an apparently instantaneous sorption reaction was followed by a slower sorption process for IO3-. For iodide a faster overall reaction meant that discrimination between the two processes was less clear. Instantaneous sorption of IO3- was greater in soils with high Fe/Mn oxide content, low pH and low organic content, whereas the rate of time dependent sorption was greatest in soils with higher organic contents. Phosphate extraction (0.15 M KH2PO4) of soils, ~100 h after 129I spike addition, indicated that concentrations of sorbed inorganic iodine (129I) were very low in all soils suggesting that inorganic iodine adsorption onto oxide phases has little impact on the rate of iodine assimilation into humus. Transformation kinetics of dissolved inorganic 129IO3- and 129I- to sorbed organic forms was modelled using a range of reaction and diffusion based approaches. Irreversible and reversible first order kinetic models, and a spherical diffusion model, adequately described the kinetics of both IO3- and I- loss from the soil solution but required inclusion of a distribution coefficient (Kd) to allow for instantaneous adsorption. A spherical diffusion model was also collectively parameterised for all the soils studied by using pH, soil organic carbon concentration and combined Fe + Mn oxide content as determinants of the model parameters (Kd and D/r2). From the temperature-dependence of the sorption data the activation energy (Ea) for 129IO3- transformation to organic forms was estimated to be ~43 kJ mol-1 suggesting a reaction mechanism slower than pore diffusion or physical adsorption, but faster than most surface reactions.
7
Fisher, Christopher John. "Structure and surface reactions of iodine and cadmium iodide on fcc(111) metal surfaces." Thesis, University of Nottingham, 1999. http://eprints.nottingham.ac.uk/13744/.
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Structural studies using the synchrotron based Normal Incidence X-Ray Standing Wave (NIXSW) technique of the copper(III)- √3x√3))R30 grad.-Iodine and copper(111)- √3x√3)R30grad.-1/2(CdI2) surfaces are presented. For the copperiodine system, the iodine was shown to adsorb in a mixture of fcc and hcp hollow sites at a distance of 2.16 ± 0.05A from the copper surface, in a (√3x√3))R30 grad. mesh. The hollow site ratio observed was 50 ± 3 % in fcc sites and 50 ± 3 % in hcp sites. For the copper-cadmium iodide system, the iodine was again shown to adsorb in a mixture of the three fold hollows, at a slightly smaller distance of 2.10 ± 0.05A from the copper surface, again in a (√3x√3)R30 grad. mesh. The ratio of occupation of the hollow sites was determined to be 37 ± 3 % in fcc sites and 63 ± 3 % in hcp sites. The copper(111)-( √3x√3)R30 grad.-Iodine surface produced by annealing the copper(111)- 1/2(CdI2) surface, was shown to have a different ratio again, at 80± 3 % in fcc sites and 20 ± 3 % in hcp sites. Possible explanations for the changing ratios are discussed including sample temperature during surface preparation, step density of the crystal, co-adsorption of adsorbate or contamination and surface coverage. The cadmium in the copper-1/2(CdI2) surface was shown to be adsorbed randomly in a mixture of the three fold hollow sites, at 2.25 ± 0.05A from the copper surface. The ratio was found to be 48 ± 3 % in fcc sites and 52 ± 3 % in hcp sites. Both studies were found to be affected by the presence of non-dipole effects in the angular distribution of the core level photoelectrons used to collect some of the data. This caused incorrect values for the standing wave structural parameters to be determined, A novel experiment was performed using two analyser geometries which enabled the importance of including the non-dipole terms in the standing wave equations to be confinned. An updated version of the standing wave equations is presented which allows quantification of and correction for the non-dipole terms. The surface reactions of iodine and cadmium iodide on an aluminium(111) surface at room temperature are shown to result in etching of the surface and the production of aluminium iodide (A1I3). For both systems, iodine forms a close-packed chemisorbed layer that has a (..J7x-..J7)R19.1° symmetry, with an iodine coverage of 3/7 of a monolayer. For the cadmium iodide surface, the cadmium is proposed as being located randomly above the chemisorbed iodine layer. With the sample liquid nitrogen cooled to low temperatures, iodine produced physisorbed multilayers, and cadmium iodide adsorbs intact, but with no ordered growth. A novel technique, Line Of Sight Sticking Probability (LOSSP), which allows the measurement of sticking and reaction probabilities is presented and applied to the I/Al system. The initial sticking probability for iodine at 300 K was determined as 0.8 ± 0.1. Under steady state etching conditions at 300 K the overall reaction probability for I2 to form AlI3, was, Rss = 0.36 ± 0.07. The surface consisted of a majority of chemisorbed iodine, with a minority of coadsorbed AlI3, with a total iodine coverage of ~ 0.6 ML. The sticking probability of I2, to solid iodine at 103 K was measured as Sphys = 0.98 ± 0.02, while the sticking probability on the halogenated surface at 300 K was measured as ~ys > 0.8 ± 0.1 Variable temperature measurements gave an activation energy for the desorption of All, of approximately 57 kJmol-1.
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Wu, Yichen. "Hypervalent Iodine as Directing Tool in Iodine-Retentive Transformation of C-H Bonds." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/461093.
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La química del iode hipervalente és una potent i versàtil eina en síntesi orgànica. En particular, els compostos orgànics de iode (III) s'han utilitzat com a oxidants de 2 electrons, així com agents de transferència de grups en diversos processos oxidatius de funcionalització. Al marge d'un nombre reduït de casos especials, aquestes transformacions van acompanyades per la pèrdua del fragment corresponent a una molècula de iodoarè. Una opció menys explorada, però sintèticament atractiva, consisteix en la incorporació tant del grup orgànic com de l'àtom de iode en el producte final. Aquest enfocament presenta un clar interès sintètic atès que la retenció de l'àtom de iode possibilita la posterior derivatització. Al llarg d'aquesta Memòria es mostren diferents reaccions d'acoblament dirigides per iode partint de compostos de iode trivalent com a substrats.
En primer lloc, es descriu un nou mètode de α-arilació directa de cetones en absència de metalls. La transferència del grup aril té lloc via acoblament orto al iode, i es basa en l'activació in situ d’aquest àtom. El nou procediment presenta bona tolerància als diferents grups funcionals del areno. La selectivitat orto es va relacionar, mitjançant càlculs DFT, amb un procés de reordanament iodonio-Claisen amb una barrera d’activació inusualment baixa. S'ha desenvolupat també un nou tipus de reaccions de benzilació regioselectiva de l'anell aromàtic a partir de derivats Ar(OAc)2 i bencil(trimetil)silà. Cal destacar que aquest procés l'acoblament carboni-carboni té lloc selectivament en la posició para respecte de l'àtom de iode. Per últim, es presenta una nova estratègia per a un procés de "iodoarilació" oxidant de l’anell imidazolic. Aquest procediment es basa en l'activació de l'enllaç NH de l'imidazol amb ArI(OAc) 2, seguida per una transferència 1,3 I-a-N del grup que dona lloc a l'obtenció de N1-aril-5-yodoimidazoles. L'impacte sintètic de la transformació emana de la inherent capacitat dels N1-aril-5-iodoimidazols d'actuar com a precursors per a diversos derivats 1,5-substituïts d'imidazol.La química del yodo hipervalente es una potente y versátil herramienta en síntesis orgánica. En particular, los compuestos orgánicos de yodo(III) se han utilizado como oxidantes de 2 electrones, así como agentes de transferencia de grupos en diversos procesos oxidantes de funcionalización. Salvo unas pocas excepciones, estas transformaciones van acompañadas por la pérdida del fragmento yodobenceno. Una opción menos explorada, pero sintéticamente atractiva, consiste en la incorporación tanto del grupo orgánico como del átomo de yodo en el producto final. Este enfoque presenta un claro interés sintético dado que la retención del átomo de yodo posibilita su posterior derivatización. A lo largo de esta Memoria se muestran distintas reacciones de acoplamiento dirigidas por el yodo partiendo de compuestos de yodo trivalente como sustratos. En primer lugar, se describe un nuevo método de α-arilación directa de cetonas en ausencia de metales. La transferencia del grupo arilo tiene lugar vía acoplamiento orto al yodo, y se basa en la activación in situ del átomo de yodo. Este procedimiento presenta buena tolerancia a los distintos grupos funcionales del areno. La selectividad orto se relacionó, mediante cálculos DFT, con un mecanismo de reorganización yodonio-Claisen con una barrera de activación inusualmente baja. Se ha desarrollado también una nueva vía de acceso para reacciones de bencilación regioselectiva del anillo aromático del ArI(OAc)2 con benciltrimetilsilano. Es interesante destacar que este proceso el acoplamiento carbono-carbono tiene lugar selectivamente en la posición para respecto del átomo de yodo. En último lugar, se presenta una nueva estrategia para la “yodoarilación” oxidante de imidazoles. Este procedimiento se basa en la activación del anillo NH-imidazólico con ArI(OAc)2, seguida por una transferencia 1,3 I-a-N del grupo arilo para la obtención de N1-aril-5-yodoimidazoles. El impacto sintético de la transformación emana de la inherente capacidad de los N1-arilo-5-iodo-imidazoles de actuar como precursores para diversos derivados 1,5-sustituidos de imidazol.
The chemistry of organic hypervalent iodine compounds has been a potent and versatile toolbox in organic synthesis. In particular, organic λ3-iodanes have been utilized as terminal 2-electron oxidants, as well as group transfer agents in a wide range oxidative functionalization processes. With few exceptions, such transformations are accompanied by the liberation of the parent organoiodine fragment. A less explored, but synthetically attractive possibility consists in incorporating both the organic group and the iodine atom into the final product. Such approach presents a clear synthetic appeal, given that the iodine retention opens the door for downstream derivatization. This thesis describes a series of such “iodine-directed” coupling reaction employing organo-λ3-iodanes as substrates. In one approach, a new method for direct metal-free α-arylation of ketones is described. The aryl transfer takes place via the coupling ortho to iodine, and is based on in situ hypervalent activation of the iodine atom. The protocol shows good functional group compatibility on the arene core. The ortho-selectivity was rationalized by DFT calculations through an unusual low-barrier “iodonio-Claisen¨ process. We also developed a new approach for regioselective benzylation of the ArI(OAc)2 cores using benzyltrimethylsilane. Interestingly, the carbon-carbon coupling now takes place selectively at para position to the iodine atom. Finally, an approach for oxidative “iodoarylation” of imidazoles was uncovered. The procedure relies on an efficient activation of the parent NH-imidazole with ArI(OAc)2, followed by copper-catalyzed intramolecular 1,3 I-to-N aryl transfer to constitute the synthetically challenging N1-aryl-5-iodoimidazoles. The importance of this manifold resides in the ability of the 5-iodoimidazoles to act as precursors for a range of 1,5-substituted imidazoles.
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Sattarzadeh, Masoud. "Determination of iron & iodine absorption from iron and iodine double-fortified salt." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq28793.pdf.
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Vandevijvere, Stefanie. "Optimizing iodine nutrition in Belgium: a selective, progressive and monitored approach to control iodine deficiency." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209599.
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Since 1990, many countries world-wide implemented salt iodisation programs in an effort totackle iodine deficiency. It was however only during the last few years that an effort was
undertaken in order to eliminate iodine deficiency as a public health problem in Belgium. In autumn 1998, a nation-wide study among children clearly showed mild iodine deficiency in
Belgium, but no action was taken before 2009. It was only in the framework of the first
National Nutrition and Health Plan 2005-2010 that iodine deficiency was formally recognized
as a public health problem. An agreement between the Ministry of Health and the bakery
sector in April 2009 aimed to encourage and increase the use of iodised salt in the
production of bread. A selective and progressive approach was used in order to keep control
and to avoid a too rapid increase of iodine intake or an excessive iodine intake among the
population. It was calculated that the net yearly savings after installation of such a program
amount to at least 14 million Euros a year.
A recent national survey among school-aged children in autumn 2010 showed a clear and
significant improvement in iodine status compared to more than 10 years ago, suggesting
iodine sufficiency among school-aged children. The median urinary iodine concentration was
however at the lower end of the optimal range and seasonal effects were not taken into
account. The improvement was at least partly linked to the increasing use of iodised salt in
the bakery industry. However, some further silent iodine prophylaxis might also have
occurred, due to changing dietary habits (milk and fish consumption). Pregnant women and
women of child-bearing age in Belgium were found to still suffer from mild iodine deficiency
according to the current recommendations. This is at least partly linked to their lower
consumption of milk and dairy drinks compared to children and due to the higher iodine
requirements during pregnancy. Although the use of iodine-containing supplements among
pregnant women was found to be quite high in Belgium compared to other European
countries, because of the low iodine status among women of child-bearing age, women
became pregnant with a suboptimal iodine status.
In view of these findings, a further increase in the use of iodised instead of non-iodised
household salt and iodised salt by the bakers is recommended. In addition, one should put
efforts in increasing awareness among the public and among health professionals with
regard to iodine-rich food sources and with regard to the use of iodine-containing
supplements starting before conception and continuing during lactation.
In order to further improve iodine status in Belgium and sustain an optimal iodine status
over time, a legal framework is necessary. Mandatory fortification of all household salt and
bread is recommended, while non-iodised alternatives could still be offered upon specific
request. A rigorous monitoring program is indispensable, including vulnerable groups such as
pregnant and lactating women and infants. In addition, sustainability is a key issue as iodine
deficiency re-emerged in several industrial countries due to lack of interest, regulations and
monitoring. Political willing, salt reduction measures, changes in dietary habits among the
population and changes in industrial practices all may affect iodine status in Belgium in the
future. Therefore the strategy of controlling iodine deficiency needs to be directed and
monitored by a Belgian Scientific Committee for the Control of iodine deficiency disorders.
Doctorat en Sciences biomédicales et pharmaceutiques
info:eu-repo/semantics/nonPublished
11
Booth, James L. "On the ortho - para enhancement of molecular iodine by selective laser excitation." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24484.
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Based upon the results reported by Balykin, V. S.r Letokhov, V. S., Mishen, V. I., and Semchishen, V. A., Chem. Phys., 17, 111 (1976), an attempt was made to shift the ortho-iodine to para-iodine ratio by (1) selectively predissociating the ortho-iodine molecules with the 5145 A argon ion laser line and (2) by reacting the selectively excited ortho molecules with the scavengers, 2-hexene, acetylene, nitric oxide, nitrosyl chloride, and ethyl iodide. In both cases the ortho to para ratio was monitored via the fluorescence induced by a scanning dye laser beam. Neither tactic prooved effective, in contradiction with the aforementionned authors. In the case of systems containing low pressures ' of iodine' vapour alone, time dependent differential quenching of the vibrational [mathematical formula omitted] transitions was observed attributed to outgasing of the test cells over the course of the experiment and may be the cause of the apparant shift claimed by Letokhov et al. In mixtures of iodine and scavenger, the null result was probably due to the formation of radical chains during the photo-induced reactions capable of rapidly relaxing any shift that had occurred.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Smit, B. S. "Cellular radiotoxicity of iodine-123." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51646.
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Thesis (MSc)--University of Stellenbosch, 2000.ENGLISH ABSTRACT: The Auger electron emitter iodine-123 was examined in the form of 4- [12311iodoantipyrineand as [12311Nal for its effectiveness in killing cells of different sensitivity to photon irradiation. Micronucleus assays showed that 4- [12311iodoantipyrineis two to three times more effective in cell inactivation than C2311Nai.This can be attributed to the fact that antipyrine, for reason of its lipid solubility, can enter cells and can reach the cell nucleus, whereas C231]Nai is excluded from the cytoplasm. The differential targeting of intra- and extracellular compartments was confirmed by radionuclide uptake experiments. In the nucleus, Auger decay conceivably is located on the DNA where it may invoke high-LET irradiation damage. Irradiation damage by [12311Naisl by long range y-irradiation and hence low-LET. Results of the present study demonstrate however that the enhancement of MN-frequency seen with 4-[123I]iodoantipyrine over [12311Nalis similar for all cell lines and that the narrowing of MN-response expected for 4- [12311iodoantipyrinedoes not occur. Experiments with the free radical scavenger, DMSO, indicated nearly identical dose reduction factors for both iodine-123 carriers. These two observations strongly suggest that the cell inactivation by 4- [12311iodoantipyrine is not by high-LET direct ionisation of DNA, but due to an indirect effect. The indirect radiation effect of Auger decay in the nucleus is attributed to shielding of DNA by histones. Such a protection mechanism is not unrealistic if it is realised that histones and DNA associate in a 1: 1 weight ratio and that higher order folding of the nucleosome chain into solenoids, loops, and chromatids generates considerable protein density. In the nucleosome core, the histone acta mer measures 7 nm and closely approximates the 10 nm dimention of the Auger electron range. It is suggested that the interlacing of protein density with DNA density suppresses direct ionisation from Auger decay at the DNA and directs the majority of Auger decay to the histones.
AFRIKAANSE OPSOMMING: Die Auger-elektron-uitstraler, jodium-123, is ondersoek in die vorm van 4- [123l]jodoantipirien en [12311Nal om die effektiwiteit te bepaal waarmee dit selle met verskillende grade van sensitiwiteit vir fotonbestraling doodmaak. Mikrokerntellings toon aan dat 4-[123I]jodoantipirien selle twee tot drie maal meer effektief inaktiveer as [12311Nal.Dit kan toegeskryf word aan die feit dat antipirien, as gevolg van sy vetoplosbaarheidseienskappe, die selle kan binnedring en die kern bereik, teenoor [12311Nalwat uitgesluit word uit die sitoplasma. Die differensiële blootstelling van intra- en ekstrasellulere gebiede is bevestig deur radionukliedopname eksperimente. In die selkern vind Auger verval waarskynlik by die DNA plaas waar dit hoë-LET stralingskade veroorsaak. Stralingskade afkomstig van [1231]Nalis deur langafstand y-strale en dus lae-LET. Die resultate van die huidige studie bewys egter dat die verhoogde mikrokernfrekwensie van 4-[12311jodoantipirienteenoor [1231]Nal dieselfde is vir al die sellyne en dat die vernouïng van mikrokernreaksie soos verwag met 4- [12311jodoantipirien, nie plaasvind nie. Eksperimente met die vryradikaalopruimer, DMSO, dui op feitlik identiese dosis-modifiseringsfaktore vir beide jodium-123 draers. Hierdie twee waarnemings is 'n besliste aanduiding dat die selinaktivering deur 4-[12311jodoantipiriennie deur hoë-LET direkte ionisering van DNA plaasvind nie, maar eerder deur indirekte stralingsaksie. Die indirekte stralingseffek van Augerverval in die kern kan toegeskryf word aan afskerming van DNA deur histone. So 'n beskermingsmeganisme is nie onrealisties nie, as in ag geneem word dat histone en DNA in 'n 1: 1 gewigsverhouding assosieer en dat hoër orde vouïng van die nukleosoomketting tot solenoïede, lusse en chromatiede 'n beduidende protïendigtheid genereer. In die nukleosoomkern is die histoon-oktameer ongeveer 7 nm in deursnit en dus vergelykbaar met die 10 nm reikafstand van die Auger elektrone. Dit word voorgestel dat die ineengeweefdheid van die protien-digtheid met die DNA-digtheid die direkte ionisering van die DNA tydens Auger verval onderdruk en dat die meeste van die Auger verval in die histone plaasvind.
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Yodle, Chan. "Iodine speciation in marine aerosol." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/56772/.
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Iodine chemistry in the marine aerosol plays important roles in the marine boundary layer such as ozone destruction and new aerosol particle formation. Iodine has a complex chemistry in the gas and aerosol phases and to date, what controls iodine speciation, the interactions and roles of individual iodine species are not well understood. This research aims to identify key controls on iodine speciation in marine aerosol. Effects of filter types on iodine and extraction methods were tested to provide optimum conditions for extraction of iodine species. Coupling of ion chromatography and inductively coupled plasma – mass spectrometry (IC-ICP-MS) for the measurement of iodine speciation was developed to provide a reliable analytical method. These optimised methods were used to determine iodine speciation in samples collected during cruises in the Atlantic Ocean (AMT21) and the Pacific Ocean (TransBrom and SHIVA). Major ions were also determined in these samples by ion chromatography (IC) with the results providing insight into the chemical characteristics aerosol samples. A high variability of the total soluble iodine (TSI) was observed between AMT21 (12–82, median 30 pmol m-3) and TransBrom (1.6–27, median 6.9 pmol m-3) and SHIVA (5.9–15, median 8.4 pmol m-3). The proportions of iodide (I-), iodate (IO3-) and soluble organic iodine (SOI) on the three cruises also showed a high variability: AMT21: I- 5.2–39%, median 14%; IO3- 36–99%, median 66%; and SOI 13–47%, median 28%, TransBrom: I- 8.8–64%, median 46%; IO3- 1.8–65%, median 6.2%; and SOI 5.9–50%, median 39%, SHIVA: I- 22–79%, median 42%; IO3- 17–66%, median 39%; and SOI non-determinable value–41%, median 14%. Three main types of aerosol with distinctive iodine speciation were identified: polluted aerosol, clean seasalt and mineral dust. pH seems to play an important role in regulating iodine speciation. The formation of HOI and the reduction of iodate are driven by acidic conditions in polluted aerosol. In clean less acidic seasalt aerosol, a high iodine enrichment was observed (565–1675, median 725), especially in the fine mode aerosol. For mineral dust, uptake of HIO3 on calcium carbonate surfaces seems to dominate.
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Lightowler, Helen. "Iodine in the vegan diet." Thesis, London South Bank University, 1997. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336909.
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Various potential nutrient deficiencies associated with the vegan diet have been thoroughly investigated, but limited research has been undertaken to assess the iodine intake of vegans. Moreover, such research may be considered unreliable. Therefore, the aims of the current work were to firstly ascertain the main sources of iodine in the vegan diet, both dietary and pharmacological, and their frequency of consumption. Secondly, it was intended, by way of a prospective cross-sectional study, to determine the iodine intake of vegans consuming their habitual diet, and their iodine status. The current sources of iodine in the vegan diet and the frequency of consumption were assessed in 378 replies to a questionnaire advertised in 'The Vegan' - the official magazine of the Vegan Society. The main sources of iodine were identified as seaweed and seaweed products, iodised salt and iodine supplements. Over 1 in 4 of the volunteers were not consuming any of these sources and 54% were consuming only one source. Conversely, 19% were consuming at least two of the three identified sources. The preliminary findings suggested that vegans may be at risk of both iodine deficiency and toxicity and that iodine consumption was largely dependent on the iodine content of the food, the portion size and the frequency of consumption. Thirty 'healthy' vegans were recruited to the prospective study. Duplicate portions and 24 hour urine specimens were collected concurrently over four consecutive days and the iodine intake and status determined by chemical analysis. Dietary intake was also recorded and iodine intakes were determined by Comp-Eat, a computerised nutritional analysis program, to assess the reliability of this dietary survey technique. The iodine intake of the majority of the subjects was below the RNI and even below the LRNI. Moreover, the iodine status of the majority of the group investigated was low. Conversely iodine intakes of those who consumed seaweed approached levels which may be considered toxic. These findings indicate that iodine intakes may be low, however it is uncertain as to whether or not the body is able to adapt to such intakes. Furthermore, the potential effect on thyroid function of possibly toxic, but infrequent, intakes of the trace element is unclear. Finally, the study exposed a need for the availability of reliable information on iodine for vegans.
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Parthipan, Rajendran. "Aqueous chemistry of iodine in seawater: Potential chemical sources of iodine in the marine atmosphere." Thesis, University of York, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488743.
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Shea, James Christopher 1964. "Hyperfine structure in the microwave spectra of the iodine fluorides iodine heptafluoride and iodine pentafluoride and of the weakly bound complex hydrochloric acid...nitrous oxide." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277178.
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A pulsed-beam fourier transform microwave spectrometer was used to measure the rotational spectra of iodine heptafluoride, iodine pentafluoride, and the weakly bound complex, HCl...NNO. For IF7, only five rotational transitions were observed, and no resolvable hyperfine structure was detected. Based on this data, the A, B, and C rotational constants were determined to be 1746(3) MHz, 1732.0(8) MHz, and 1553.0(2) MHz, respectively. The existence of a pure rotational spectrum confirms that this molecule undergoes polar distortions. Twenty-two hyperfine components of the IF5 spectrum were recorded. The B rotational constant for this molecule was determined to be 2727.421(3) MHz, and the quadrupole coupling constant was found to be 1069.35(13) MHz. Though the work is still in progress on HCl...NNO, nine transitions have been recorded. In addition, five transitions have been recorded for an apparent trimer species composed of HCl, NNO, and an as yet unidentified third species.
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Babicheva, Rosalie. "Radiation doses to family members of patients treated with Iodine-131 therapy." Connect to full text, 2001. http://hdl.handle.net/2123/5318.
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Thesis (M. App. Sc.)--University of Sydney, 2001.Title from title screen (viewed Aug. 11, 2009) Includes tables. Submitted in fulfilment of the requirements for the degree of Master of Applied Science to the Faculty of Health Sciences. Includes bibliographical references. Also available in print form.
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Fong, Ka-wah Martin. "Adaptation of a simplified method for urinary iodine for studying the iodine status of local Chinese." Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B31971726.
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Fong, Ka-wah Martin, and 方家華. "Adaptation of a simplified method for urinary iodine for studying the iodine status of local Chinese." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31971726.
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Bowley, Hannah E. "Iodine dynamics in the terrestrial environment." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13241/.
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The aim of this work was to investigate the effect of soil properties on soil iodine dynamics and uptake to plants. Soil and vegetation samples were collected from across eastern Northern Ireland (NI) to form the basis of most experimental work; samples from the Rothamsted Park Grass archive were used to investigate the role of changing soil chemistry through time and due to selected fertiliser applications; and iodine dynamics in humic acid (HA) were studied to improve understanding of the role of organic matter in soils. Input of iodine in rainfall was considered in the context of samples from both locations, and the additional influences of coastal proximity, soil type and underlying geology were reviewed for the NI samples. Total iodine analysis was carried out using extraction with TMAH and quantification by ICP-MS; aqueous iodine speciation was determined using HPLC and SEC coupled with ICP-MS. The most important iodine inputs to both soil and vegetation were found to be directly from the sea in coastally-exposed locations, and from rainfall in other cases. Soil organic matter (measured as soil organic carbon, SOC) was determined to be involved in both retaining a portion of recalcitrant iodine in soil and HA, and in promoting sorption of both iodide and iodate in highly organic soils. Metal oxides (Fe, Mn and Al) were found to be important in rapid sorption of iodate to soils with SOC ≤ 38 %, and there was an indication that they may be involved in promoting the reaction of iodide with organic matter. Replenishment of a transient phyto-available pool was essential for provision of iodine to vegetation. The availability of recently added iodine (as 129IO3-) in the pot experiment was controlled by its sorption onto the solid phase, and near-constant input from irrigation water was the major source of vegetation iodine in most cases. Rainfall was shown to be important in controlling vegetation iodine concentrations in field situations. In soils collected from very coastally-exposed locations, the soil iodine concentration was extremely high and therefore a greater proportion of labile native iodine was available for uptake; irrigation sources were much less important. This work improves understanding of soil iodine dynamics and the important factors controlling iodine speciation and availability to plants. Results can be used to inform practices regarding provision of iodine to crops for both humans and grazing animals.
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Nahavandi, Mona. "Iodine induced structures on Cu(100)." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-102816.
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Replacing the expensive platinum layer in the dye-sensitized solar cells (DSSC) with cheaper materials can reduce the cost of these types of solar cells dramatically. In this study, the possibility of replacing the Pt layer with Cu is investigated. For this purpose, iodine which is used as electrolyte in dye-sensitized solar cells was deposited on the Cu(100) surface. Different amounts of Iodine was adsorbed on the surface, and consequently different iodine structures are observed. Low Energy Electron Diffraction (LEED) and Scanning Tunneling Microscopy (STM) are implemented to observe and verify the atomic structure on the Cu(100) substrate. LEED and STM images showed that iodine arranges in p(2x2), c(6x2) and c(4x2) phases on the Cu(100) surface. The study of the interface electronic properties has been done by use of photoelectron spectroscopy. Coverage dependent I4d spectra do not show any chemically shifted peaks, but a collective shift toward lower binding energy (at increasing surface concentration). The Cu3p spectra are found to be insensitive to the amount of iodine and heating; no iodide is formed on this surface. The spectroscopic results indicate a moderate Cu-I interaction and the surface atomic and electronic structure is strongly influenced by the iodine-iodine interaction in the surface layer.
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Thompson, Clare. "The role of iodine in autoimmunity." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615656.
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Chang, Ching-Chih, and Ching-Chih Chang. "Iodine-129 as an Oceanic Tracer." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621856.
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The long-lived radionuclide ¹²⁹I (half-life: 15.7 × 10⁶ yr) is well-known as a useful environmental tracer. At present, the global ¹²⁹I in surface water is about 1-2 orders of magnitude higher than pre-1960 levels. In order to understand the spread of ¹²⁹I in the Pacific Ocean, ¹²⁹I time series from corals and seawater were reconstructed. Two iodine extraction methods were tested and compared to optimize the yield and precision of the measurements. A solvent extraction method was chosen over a resin column preparation technique giving that it provides higher signal and lower error. Coral ¹²⁹I time series records from the Western Pacific including Con Dao and Xisha Islands, in the South China Sea; Rabaul, Papua New Guinea, in the South Pacific; and Guam in the North Pacific were reconstructed and pathways and sources of ¹²⁹I from the 1950s onward were assessed. Nuclear weapons testing was the primary ¹²⁹I source to the ocean, notably from testing in the Marshall Islands and radiogenic iodine was carried primarily through surface ocean currents. A seawater ¹²⁹I monitoring program was instituted with seawater samples from Scripps Pier, La Jolla, California, USA a few months after the Great East Japan Earthquake, which involved the accidental release of substantial amounts of ¹²⁹I from the Fukushima Daichi nuclear power plant. These data were used to construct a 4-year record of surface water ¹²⁹I with monthly resolution. ¹²⁹I in Hanford site vicinity is also surveyed to understand the background value of the California Current System. It is clear that the California Current System is influenced by the Hanford site which can explain the higher ¹²⁹I/¹²⁷I background values observed along the west coast of the U.S. compared to other surface sites in the Pacific Ocean. Our result shows that the highly contaminated seawater from the Fukushima Daiichi Nuclear Power Plant accident has not yet seen at the Scripps Pier, La Jolla, California, USA four years of ocean transport.
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MacDonald, Samantha Marie. "Iodine chemistry in the remote troposphere." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/6356/.
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Measurements of the flux of I2 and HOI from the heterogeneous reaction of gaseous ozone with aqueous iodide were performed by conversion to iodine oxide particles and detection using a nano-differential mobility analyser. Fluxes were measured as a function of [O3], [I-], salinity, temperature, and in the presence of organic species. A linear response was observed for O3 and salinity; iodide showed some deviation at higher concentrations. The temperature dependence of the I- + O3 reaction was found not to be significant and none of the organic species investigated had a significant effect on the resulting I2 and HOI fluxes. A kinetic model of the interfacial layer was then employed to verify the experimental results and good agreement was found, apart from observations at high iodide where the I2 flux was over-predicted. Parameterised expressions for the flux of I2 and HOI were then produced from the model outputs using multiple linear regression analysis. The differential optical absorption spectroscopy (DOAS) technique was used to measure IO on the Galapagos Islands in the Eastern Pacific. The long path (LP) DOAS instrument was unable to measure IO above the detection limit (0.9 pptv) and measurements from the multi-axis (MAX) DOAS instrument ranged from below the detection limit to 0.9±0.2 pptv. IOx (IO + I) was inferred from the measured O3 concentrations and correlation analyses were conducted with available ancillary measurements (O3, wind speed, temperature) and satellite data (Chl-a, CDOM, SST, and salinity). A significant positive correlation was observed with both SST and salinityand this was linked to variations in sea surface I-. The parameterised expressions for I2 and HOI were then input into the 1-D chemistry-transport model THAMO (Tropospheric HAlogen chemistry MOdel) to compare the predicted IO and IOx mixing ratios with measurements performed on the Cape Verde islands in the Atlantic ocean and during the HaloCarbon Air Sea Transect-Pacific (HaloCAST-P) cruise in the Eastern Pacific. The predicted fluxes were in agreement at higher wind speeds, however, at lower wind speeds, IO was over-predicted byaround a factor of three; O3 concentrations were reduced to 2 ppb (20 times lower than calculated) to match the observations.
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Theiss, Frederick L. "Removal of iodine using LDH technology." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/100206/11/Frederick_Theiss_Thesis.pdf.
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This project has investigated the removal of iodine species from wastewater using LDH technology. This research focused on initial laboratory scale experiments to assess the suitability of this methodology as a cost effective means of treating water contaminated with radioiodine from industrial and medical wastes.
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CATANOSO, MARCELA F. "Purificação de sup(123)I e sup(131)I para marcação de biomoléculas." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10025.
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Made available in DSpace on 2014-10-09T12:33:57Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:03:04Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Babicheva, Rosalie. "Radiation doses to family members of patients treated with Iodine-131 therapy." Master's thesis, School of Medical Radiation Sciences, Faculty of Health Sciences, 2001. http://hdl.handle.net/2123/5318.
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Thesis (M. App. Sc.)--University of Sydney, 2001.Title from title screen (viewed Aug. 11, 2009) Includes tables. Submitted in fulfilment of the requirements for the degree of Master of Applied Science to the Faculty of Health Sciences. Includes bibliographical references. Also available in print form.
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Jia, Zhiyu. "Transformations promoted by the hypervalent iodine reagents." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/134832.
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Malmedy, Florence. "Stereoselective transformations using chiral hypervalent iodine reagents." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/93576/.
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Hypervalent iodine (III) compounds are efficient, selective and environmentally friendly reagents. Due to their electrophilic nature and excellent leaving group ability, they can be used to mediate oxidative transformations; for example, the oxidation of sulfides to sulfoxides, the α-functionalisation of ketones, the dearomatisation of phenols, the functionalisation of alkenes and, more recently, the rearrangement of various substrates. In this thesis, the stereoselective rearrangement of propiophenone derivatives mediated by chiral hypervalent iodine reagents is described (Scheme i). A chiral lactate-based iodine (III) reagent was used to synthesise 2-arylpropionate derivatives with moderate to good yields and enantioselectivities. These compounds are highly attractive as they are direct precursors to Non-Steroidal Anti Inflammatory Drugs (NSAIDs). Scheme i. Rearrangement of propiophenone derivatives to 2-aryl-propionates. The cyclisation of malonate derivatives, mediated by hypervalent iodine reagents has also been investigated (Scheme ii). Several lactone derivatives were synthesised with this method, achieving moderate to good yields. Scheme ii. Cyclisation of malonate derivatives to synthesise functionalised lactones. Finally, the design of a new hypervalent iodine reagent is described (Figure i). After its synthesis, the pyridine-based reagent was tested in several model reactions, usually mediated by iodine (III) reagents. Its reactivity was similar to the one of other hypervalent iodine reagents. However, its ability to induce stereoselectivity to different products was quite poor. Figure i. Structure of the new hypervalent iodine reagent.
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Zhou, Xiang. "Electric field induced predissociation of molecular iodine." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/29903.
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Electric field induced predissociation of the B ³∏₀[formula omitted] electronic state of molecular iodine has been investigated. The flourescence spectra of I₂ , corresponding to the upper vibrational
quantum mumber v'= 4 to v'= 10 have been recorded with and without a high electric field applied. Because these levels have a large natural predissociation, a specially designed high voltage cell has been built and electric fields up to 140kV/cm have been applied in order to observe the induced predissociation. By combining our results with the previous work by Dalby et al.[10] (from v'= 10 to v'= 22), we have the most complete predissociation data for I₂ . Both numerical and semiclassical treatments have been used to analyse the data. The form of the interacting repulsive potential curve, ³∏₁[formula omitted], has been revised.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Nugraha, Tutun. "Iodine retention on stainless steel sampling lines." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28825.pdf.
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Furman, Scott Anthony. "Surface chemistry of iodine on platinum (111)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ36639.pdf.
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Jianping, Lin. "Iodine speciation in the Yarra River estuary /." Connect to thesis, 1992. http://eprints.unimelb.edu.au/archive/00000216.
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Edmunds, J. J. "Novel fluorination reactions via hypervalent iodine reagents." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47045.
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Antien, Kevin. "Développement de nouveaux réactifs iodés hypervalents chiraux hélicéniques. Synthèse collective stéréodivergente d’alcaloïdes de Securinega." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0349/document.
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La chimie des composés iodés hypervalents, ou organoiodanes, suscite un engouement croissant de la part de la communauté scientifique depuis maintenant près de 30 ans. Les efforts de recherche sont de nos jours orientés de manière prépondérante vers des applications en synthèse asymétrique, principalement au travers de l’utilisation d’architectures organoiodées chirales. À ce jour, seules les chiralités centrales et axiales sont exploitées dans l’élaboration de tels objets. L’emploi d’iodanes achiraux (i.e. en synthèse asymétrique) en présence d’additifs chiraux a par ailleurs été largement négligé par la communauté. La chiralité hélicoïdale est incarnée en chimie organique par les hélicènes. Ces composés polyaromatiques sont des objets fascinants de par leurs propriétés structurelles, électroniques et chiroptiques hors du commun. Ils sont le centre d’une attention considérable dans de nombreux domaines de recherches allant de la catalyse asymétrique à l’élaboration de diodes électroluminescentes organiques. Jamais la chiralité hélicoïdale n’a été exploitée en chimie de l’iode hypervalent. Ces travaux de thèse traitent en premier lieu de l’élaboration d’une méthodologie asymétrique de désaromatisation oxygénante de phénols faisant usage d’un iodane-3 achiral en présence d’un agent de transfert de phase issu des alcaloïdes du Quinquina. Dans une seconde partie de ces travaux est abordée la synthèse asymétrique d’un nouvel iodoarène hélicénique et ses premières applications dans des réactions de désaromatisation oxygénante de phénols. Cet ouvrage traite également dans un troisième chapitre d’une synthèse totale, collective et stéréodivergente de 12 alcaloïdes de Securinega. Il s’agit d’une classe métabolites secondaires retrouvés dans de multiples plantes des genres Securinega (Flueggea), Phyllanthus, Margaritaria et Breynia de la famille Phyllanthaceae. Depuis près d’un demi-siècle, la biogénèse de ces molécules naturelles demeure partiellement incomprise. La synthèse développée dans ce travail a pour vocation d’améliorer la compréhension du mécanisme biosynthétique à l’origine de ces substances. Il a ainsi été établi qu’une étape clé de condensation aldolique pourrait permettre d’expliquer la stéréodivergence observée dans la natureHypervalent iodine chemistry has been arousing the interest of the scientific community for the last 30 years. Research efforts are now mainly directed towards applications in asymmetric synthesis, notably through the use of chiral organoiodine scaffolds. To this end, solely central and axial chiralities have been exploited to construct such objects. The use of achiral iodanes (i.e. hypervalent organoiodine compounds) in asymmetric synthesis has been largely neglected by the community. Helical chirality in organic synthesis is mainly found in polyaromatic compounds known as helicenes. These molecules exhibit fascinating structural, electronic and chiroptical properties. They are the center of considerable attention across many fields of research, spanning from asymmetric catalysis to organic light-emitting diodes. Helical chirality has never been exploited in the field of hypervalent iodine chemistry. In the first part of this doctoral work, a methodology for the asymmetric oxygenative dearomatization of phenols by an achiral 3-iodane in the presence of a Cinchona-alkaloid-based phase transfer agent was developed. The second part of this manuscript details the synthesis of a new helicenic organoiodine compound and its application to oxygenative phenol dearomatization reactions. In the last chapter of this doctoral dissertation is described the total, collective and stereodivergent synthesis of 12 Securinega alkaloids. These natural products are commonly found in plants belonging to the genera Securinega (Flueggea), Phyllanthus, Margaritaria and Breynia of the Phyllanthaceae family. Even after little less than half a century of research, the real biogenetic pathway used by nature to construct these molecules is still only partly understood. The chemical synthesis developed in this doctoral work provides a better understanding of the biosynthetic mechanism. It was established in the course of this work that a key aldol condensation step could shed light upon the stereodivergence observed in nature
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Kar, Adwitiya. "Novel 125 I production and recovery system." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1534.
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Romero, Segura Rafael Martín. "Development of hypervalent iodine(iii)-mediated chemical reactions." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/402470.
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El iode hipervalent representa una poderosa eina per dur a terme diferent reaccions d’oxidació en condicions lliures de metalls. S’han realitzat estudis mecanístics que inclouen experiments de control físic-orgànics relatius a la diaminació intermolecular d’alquens mediats per iode(III) que han servit per a demostrar la veracitat dels càlculs computacionals realitzats prèviament.
Aquesta informació va proporcionar una visió crucial per al desenvolupament d’una nova reacció enantioselectiva de diaminació d’estirens catalitzada per iode(III). El disseny d’un nou catalitzador quiral de iode basat en l’ús de l’àcid làctic com a font econòmica de quiralitat representa la clau d’aquest assoliment. L’optimització del catalitzador implica l’increment de la densitat d’electrònica en el nucli de iode i un motiu d’amida secundària en la cadena lateral de lactat quiral. Entre els diferents oxidants terminals, el mCPBA ha resultat ser el més eficient conduint a bons rendiments i excel·lent enantioselectivitats (>99% ee). L’abast de la reacció comprèn alquens terminals i alquens interns dins del motiu de l’estirè.
En un estudi addicional, es va aconseguir la formació d’un nou enllaç carboni-bor. Així doncs, la borilació de sals de diariliodoni va ser possible després d’identificar el contra-anió del reactiu de diariliodoni més adequat. Mitjançant la generació in situ umpolung al centre de bor, la seva arilació per el reactiu hipervalent esdevé possible. Amb aquest fi, diferent acetats de diariliodoni van ser sintetitzats, demostrant la gran aplicabilitat d’aquest nou mètode respecte al grup aromàtic transferible. Aquest mètode s’afegeix a l’escàs nombre de reaccions de borilació en condicions lliures de metalls.Los reactivos de iodo hipervalente representan una herramienta muy poderosa para la realización de diferentes oxidaciones libres de metal. Se llevaron a cabo estudios mecanísticos incluyendo experimentos físico-orgánicos de control respecto a la diaminación intermolecular de alquenos, demostrando la veracidad de los cálculos DFT previamente realizados. Esta información resultó crucial para el desarrollo de una pionera diaminación enantioselectiva de estirenos catalizada por iodo(III). Uno de los mayores logros es el diseño de un nuevo catalizador de iodo quiral basado en el ácido láctico como fuente económica de información estereoquímica. La optimización del catalizador incluye un aumento crucial de electrondensidad en el núcleo de iodo y la presencia del grupo amida en la cadena de lactato quiral. Entre los diferentes oxidantes terminales probados, mCPBA resultó ser el más eficiente, dando buenos rendimientos y una enantioselectividad sin precedentes, siendo ésta siempre superior al 90% ee. Esta reacción puede extenderse a alquenos terminales e internos que contengan la estructura de estireno. Este logro representa uno de los resultados más avanzados en la diaminación asimétrica de alquenos. En un estudio adicional, se consiguió una nueva formación de enlaces carbono-boro. Aquí, la borilación de sales de diariliodonio fue posible tras la identificación de un contraión apropiado en el reactivo de diariliodonio. Gracias a la generación in situ de un umpolung en el centro de boro, su arilación por el reactivo hipervalente es posible. Con esta finalidad, se sintetizaron diferentes acetatos de diariliodonio y se demostró la gran aplicabilidad de esta metodología en la transferencia de grupos aromáticos. Este protocolo representa uno de los pocos procesos económicos de borilación en ausencia de metal.
Hypervalent iodine(III) reagents represent a powerful tool for the realisation of different metal-free oxidation reactions. Mechanistic studies including physical-organic control experiments concerning the oxidative iodine(III)-mediated intermolecular diamination of alkens were carried out, demonstrating the veracity of previous DFT calculations. This information provided crucial insight for the development of a pioneering iodine(III)-catalysed enantioselective diamination of styrenes. The design of a novel chiral iodine catalyst based on lactic acid as economic chiral information source represents the key accomplishment. Catalyst optimisation involves a crucial electrondensity enhancement at the iodine core and a secondary amide motive in the chiral lactate side chain. Among different terminal oxidants, conventional mCPBA emerged as the most efficient one leading to good yields and unprecedented enantioselectivities of above 90% ee. The scope of the reaction comprises terminal and internal alkenes within the styrene motif. It represents the state of the art in asymmetric diamination of alkenes. In an additional study, a novel carbon-boron bond formation was accomplished. Here, borylation of diaryliodonium salts was encountered feasible upon identification of a suitable counterion in the diaryliodonium reagent. By generating an in situ umpolung at the boron centre, its arylation by the hypervalent reagent becomes viable. To this end, different diaryliodonium acetates were synthesised, thereby successfully demonstrating a broad applicability of this new methodology regarding the transferable aromatic group. This protocol adds to the still scarce number of economic borylation reactions under metal-free conditions.
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Narayanan, Anandhi. "Global model for iodine behaviour in reactor containment." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0020/MQ53344.pdf.
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Page, Thomas Keri. "Synthesis and reactivity of chiral hypervalent iodine compounds." Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54874/.
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Hypervalent iodine compounds are molecules of increasing interest to the synthetic chemist. Their low toxicity when compared to heavy metal reagents and their ease of use in the laboratory are helping to establish them into the armoury of the synthetic chemist. More recently, research into chiral hypervalent iodine compounds has been the main focus. The work performed during this research tenure is based upon the development of new chiral hypervalent iodine reagents for use in stereoselective synthesis and this research can be summarised into three main sections: Synthesis of novel chiral iodine(III) compounds; Reactivity of chiral iodine(III) compounds; Novel oxididative procedure. The synthesis of new chiral iodine(III) compounds and their use in asymmetric oxidative functionalisations are described herein. The use of stoichiometric quantities of these iodine(III) reagents with 1 eq of pTsOHO in the a-oxytosylation of ketones and 2 eq of /7TSOH H2 O in the dioxytosylation of alkenes, have given the corresponding products in good yields, 57-76% (3-12% ee) and 48-75% (9-16% ee) respectively. Additionally, a new catalytic method is described in which the presence of a stoichiometric oxidant, 1 eq of /7TSOH H2O and only catalytic quantities of the chiral iodine(I) reagent is necessary to afford a-oxytosylated ketones. The final aspect of the research has dealt with the problems associated with oxidizing iodine(I) compounds to iodine(III) compounds. The development of a new method to oxidise iodine(I) compounds to bis(trifluoroacetoxy)iodo arenes through the use of urea-hydrogen peroxide adduct and trifluoroacetic anhydride is also described.
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Filtness, Michael Jane. "Investigating the early solar system using iodine-129." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497443.
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This study forms part of an ongoing attempt to understand and employ the iodine xenon system as a chronometer. This work addresses issues that previous work has brought to light. By studying samples of primitive LL chondrites (Bishunpur LL3.1, and Kiymka LL3.1), 1 have investigated whether I-Xe ages in these meteorites date formation or post-formation processes, and have explored the causes of post-formation resetting. The results of this study indicate that late chondrule I-Xe ages in LL3 chondrites reflect resetting events caused by collisions, not formation.
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Poulton, Miriam. "Iodine deficiency in the Northern Punjab of Pakistan." Thesis, University College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267658.
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Pruenglampoo, Sakda. "Dietary iodine intake during pregnancy and birth outcome." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243117.
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Jegasothy, Shankar. "Kinetic studies on polymer-supported hypervalent iodine oxidants." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615044.
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Ji, Chen. "Salt intake and iodine status around the world." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/57708/.
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Background: Salt reduction and universal salt iodisation programmes are implemented worldwide to prevent cardiovascular disease and iodine deficiency disorders, respectively. Concerns have been raised regarding the potential policy conflicts, and a programme coalition is proposed by the World Health Organization to optimise salt and iodine intakes at population level. This study aimed 1) to estimate population salt intake and iodine status in index countries; 2) to investigate the association between salt and iodine intakes; 3) to assess the impact of salt intake modification on iodine status; 4) to estimate the determinants of and potential geographical variation in salt and iodine intakes where data are available; and 5) to provide suggestions to policy makers. Data and Methods: In the ecological analysis, national estimations of salt and iodine intakes were extracted from international organisation databases and published papers. Three case studies used population level data obtained from the Kumasi Salt Reduction Study in Ghana, the Third United States National Health and Nutrition Examination Survey (NHANES III) and the 2000-01 UK National Diet and Nutrition Survey 19-64 years (NDNS). Linear regression was used in the Kumasi analysis, and Bayesian geo-additive models were used in the other two analyses by accounting for the spatial effect and important linear and nonlinear risk factors. Results: Salt intake varied between countries, with Kumasi lower than the western countries. Iodine status also varied by country, but with no consistent association with salt intake. A moderate salt reduction programme is unlikely to have a major impact on iodine status in countries committed to universal salt iodisation, provided that iodine concentration is titrated to actual salt intake, maximum coverage is achieved as in China and iodised salt becomes part of food processing. At least in Britain, high salt intake is associated with low socioeconomic status, irrespective of geographic location. Conclusions: Policy-makers may therefore need to adjust iodine content in salt in accordance with each country’s context. The Bayesian geo-additive models are useful for monitoring and evaluating salt reduction and iodine supplementation.
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Bruzzese, John Reed. "Development of an Electric Discharge Oxygen-Iodine Laser." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308228482.
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Atkinson, Helen. "Iodine in sea ice and the polar atmosphere." Thesis, University of East Anglia, 2011. https://ueaeprints.uea.ac.uk/40451/.
Full textAbstract:
The volatilisation of iodine from the ocean and release to the atmosphere in the ice-covered polar regions has been studied. Laboratory experiments involving sea ice- and ice associated- diatoms have shown how the extreme conditions experienced in sea ice brine channels may lead to an increase in production of organic forms of iodine. Trends were observed in production by different classes of enzymes, active in the oxidative metabolism of the cell. An enhancement in trace gas concentrations due to the concentration effect of solvent volume reduction has also been demonstrated. Field campaigns have been undertaken in both the Arctic and Antarctic. Ship-based measurements in the Weddell Sea have implicated I2 as a key species in the mechanism of enhancement of atmospheric iodine in this region. Organic and inorganic forms of iodine were measured in seawater, sea ice and the atmosphere. On the Brunt ice shelf, enhanced concentrations of CH3I and C2H5I were measured in the snow firn air, with a diurnal profile, suggesting the snow may be a source of these compounds. These measurements have implications for atmospheric mixing ratios of IO, measured from the ship and validated by satellite data, and new particle formation. This is the first combined in situ study in Antarctica of organic and inorganic iodine compounds in sea water, ice and air. On the Western Antarctic Peninsula, IO was detected in the atmosphere, and seawater measurements of iodocarbons have demonstrated how organic compounds of iodine are enhanced during the phytoplankton bloom; these measurements are also a first. Iodine emissions in the sea ice zone were also quantified in two campaigns in the Arctic environment. High concentrations of halocarbons were measured in the brine of sea ice, with respect to the water below, in the Arctic Ocean. High atmospheric halocarbon mixing ratios and flux calculations have demonstrated the effect on the atmosphere above. In the Canadian sub-Arctic, where the ice had quite different physical properties, halocarbon concentrations were the highest ever recorded for some compounds, due to extreme concentration in very cold ice. The enhancement of organic forms of iodine in sea ice has therefore been demonstrated. I2 has been implicated as a key species in iodine emissions. Therefore, understanding has been furthered on the chemistry of iodine in sea ice and polar atmosphere.
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Pikelnaya, Olga. "Reactive iodine species at North American coastal sites." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1773833421&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Gurung, Ras Kumari. "INVESTIGATIONS OF HYPERVALENT IODINE COMPOUNDS IN ORGANIC TRANSFORMATIONS." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/dissertations/991.
Full textAbstract:
The main aim of the work presented here is to develop new, practical, economical, and environmental friendly synthetic protocols for various organic transformations with hypervalent iodine compounds, which have attracted explosive interest among chemistry communities because of their versatility and mildness in inducing many organic transformations. Chapter 1 briefly introduces the history of hypervalent iodine compounds, nomenclature, classification, bonding and reactivity patterns. The preparation and practical applications of typical I(III) and I(V) compounds have also been briefly surveyed. Chapter 2 provides details on hypervalent iodine compounds catalyzed oxidation of benzylic C-H to the corresponding carbonyl compounds with Oxone. The catalytic efficiency is influenced by the rate of in situ generation of catalyst with Oxone and their stability. The effectiveness in situ generated 35', 50' and 51' are almost the same, leading to low to moderate yields of products, while 18 and 47' give moderate to high yields. Compound 48' was founds to be the most active catalyst in this study. A possible mechanism is also proposed. Chapter 3 covers a surprising reaction between IBX or IBA and alkyl halides promoted by quaternary ammonium halides. In the absence of quaternary ammonium halides, no reaction occurred between IBX or IBA and alkyl halides. However, in the presence of quaternary ammonium halides, IBX or IBA and alkyl halides react smoothly to form the corresponding alkyl iodobenzoates. When IBX or IBA is treated with a quaternary ammonium halide, it will decompose to 2-iodobenzoic acid. The presence of a nucleophilic halide ion is essential for such reaction to occur. Replacing halides with non-nucleophilic BF4- halts the reaction. Benzylic halides provides a better yield than aliphatic alkyl halide. Thus, it is believed that there is a fast interaction between the nucleophilic halides and electrophilic iodine in IBX or IBA. A plausible reaction mechanism is proposed. Chapter 4 details our research on the oxidative cleavage of C=C with PIFA/water. In the presence of a small amount of water in acetonitrile at 65-70 oC, [bis(trifluoroacetoxy)iodo]benzene (PIFA, 26) converts styrenes into benzaldehydes in good to high yields. Contrary to literature description that electron-rich styrenes primarily produces phenylacetaldehydes as major products through a 1, 2-phenyl migration, we have found that these styrenes can be converted to benzaldehydes in high yields. It was found that three equiv of 26 and one equiv of water were necessary to achieve high yields. Two pathways were believed responsible for the high yield of benzaldehydes: (1) cleavage of the glycol intermediates; (2) further oxidative cleavage of the 1, 2-phenyl migration product - phenylacetaldehydes. Chapter 5 describes a preliminary investigation on perfluoroalkylation reaction of styrene with [bis(trifluoroacetoxy)iodo]butane (32). p-t-Butylstyrene reacts with 32 in the presence of water produced moderate yields of hydroxyperfluorinated product, 1-(4-tert-butyl-phenyl)-3,3,4,4,5,5,6,6,6-nonafluoro-hexan-1-ol (73), along with 1-(4-tert-butyl- phenyl)-2-iodo-ethanol (72) and 1-(4-tert-butyl-phenyl)-ethane-1,2-diol (74). Electrophilic addition of 32 on the C=C bond, hydration of the intermediate, and reductive elimination were believed to have been involved. Chapter 6 summarizes all of the work carried out in the previous chapters and provides some insight into future studies.
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Balaji, A. "Analysis Of Solar Pumped Chemical Oxygen Iodine Laser." Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/238.
Full textAbstract:
Chemical Oxygen Iodine Laser(COIL) is an electronic transition high energy chemical laser having a wavelength of 1.315 /mi. This is the first chemical laser to operate on an electronic rather than a rotational or vibrational transition. In principle the COIL can be operated either in pulsed or cw mode. Its interest lies in high chemical efficiency, high power and wavelength which is shortest among all the chemical lasers. COIL finds a wide range of applications as its output wavelength at 1.315/zm couples well with the surface of most metals. The applications include surface hardening and modification of metals, welding, drilling and cutting of metals, cutting of ceramics, micro machining, laser deposition of non metallic coatings on metallic surfaces, monitoring of atmospheric pollutants and solar hazardous waste detoxification. Moreover, its wavelength is suitable for fiber optic transmission.
In COIL the laser output at 1.315 /an is achieved by stimulated emission on the f (2-PL/2) -* -f (2-p3/2) magnetic dipole transition in atomic iodine. The population inversion on this transition is obtained by resonant collisions! energy transfer from metastable excited Oj^A) molecules produced by a chemical reaction of KOH, H2O? and Cl2. The chemical reaction of H2O2 and Cl2 that produces oxygen molecules is highly exothermic, and because of spin conservation considerations, channels its energy directly into the metastable electronically excited singlet delta state of oxygen molecule. Since the O2(1A) has a 45 mins lifetime and hence an extremely low small signal gain coefficient, it cannot be lased directly. Lasing can be achieved, however, if this energy is transferred to an atom or molecule which has a reasonable transition moment between its excited and ground states. The iodine 52P^2 -> 52P3/2 magnetic dipole transition has an acceptable transition moment and is nearly resonant with the 02{lA) state in oxygen. Excited iodine atoms are obtained by mixing O2(l A) and l2 molecules resulting in their dissociation and subsequent excitation.
Power levels in excess of 25 kW have been reported in COIL. Due to wide range of applications and mainly for its use as a laser weapon, efforts are being made to enhance the power to higher levels. The dissociation of I2 controls the gain of the coil and hence power. In the pure COIL scheme some of the I2 remains undissociated due to the recombination reactions. Hence if we add a mechanism to dissociate the residual I2 molecules, we can enhance the performance of the COIL. So we propose to add a solar pumping to conventional COIL, which by photo exciting the undissociated I2lead to increase in efficiency.
The thesis contains six chapters in which chapter 1 contains a general introduction and the definition of the research problem. The basic theory and the chemical reactions are discussed in chapter 2, The proposed model is discussed and the rate equations are solved in chapter 3. The numerical scheme and the computer code along-with the validation of the code are presented in chapter 4. The numerical results for the species concentrations, population inversion density and the output power for the proposed solar pumped COIL are presented in chapter 5, Final conclusions and future scope of the proposed research are presented in the final chapter 6.
(Pl refer the original document for formulas)
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Balaji, A. "Analysis Of Solar Pumped Chemical Oxygen Iodine Laser." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/238.
Full textAbstract:
Chemical Oxygen Iodine Laser(COIL) is an electronic transition high energy chemical laser having a wavelength of 1.315 /mi. This is the first chemical laser to operate on an electronic rather than a rotational or vibrational transition. In principle the COIL can be operated either in pulsed or cw mode. Its interest lies in high chemical efficiency, high power and wavelength which is shortest among all the chemical lasers. COIL finds a wide range of applications as its output wavelength at 1.315/zm couples well with the surface of most metals. The applications include surface hardening and modification of metals, welding, drilling and cutting of metals, cutting of ceramics, micro machining, laser deposition of non metallic coatings on metallic surfaces, monitoring of atmospheric pollutants and solar hazardous waste detoxification. Moreover, its wavelength is suitable for fiber optic transmission.
In COIL the laser output at 1.315 /an is achieved by stimulated emission on the f (2-PL/2) -* -f (2-p3/2) magnetic dipole transition in atomic iodine. The population inversion on this transition is obtained by resonant collisions! energy transfer from metastable excited Oj^A) molecules produced by a chemical reaction of KOH, H2O? and Cl2. The chemical reaction of H2O2 and Cl2 that produces oxygen molecules is highly exothermic, and because of spin conservation considerations, channels its energy directly into the metastable electronically excited singlet delta state of oxygen molecule. Since the O2(1A) has a 45 mins lifetime and hence an extremely low small signal gain coefficient, it cannot be lased directly. Lasing can be achieved, however, if this energy is transferred to an atom or molecule which has a reasonable transition moment between its excited and ground states. The iodine 52P^2 -> 52P3/2 magnetic dipole transition has an acceptable transition moment and is nearly resonant with the 02{lA) state in oxygen. Excited iodine atoms are obtained by mixing O2(l A) and l2 molecules resulting in their dissociation and subsequent excitation.
Power levels in excess of 25 kW have been reported in COIL. Due to wide range of applications and mainly for its use as a laser weapon, efforts are being made to enhance the power to higher levels. The dissociation of I2 controls the gain of the coil and hence power. In the pure COIL scheme some of the I2 remains undissociated due to the recombination reactions. Hence if we add a mechanism to dissociate the residual I2 molecules, we can enhance the performance of the COIL. So we propose to add a solar pumping to conventional COIL, which by photo exciting the undissociated I2lead to increase in efficiency.
The thesis contains six chapters in which chapter 1 contains a general introduction and the definition of the research problem. The basic theory and the chemical reactions are discussed in chapter 2, The proposed model is discussed and the rate equations are solved in chapter 3. The numerical scheme and the computer code along-with the validation of the code are presented in chapter 4. The numerical results for the species concentrations, population inversion density and the output power for the proposed solar pumped COIL are presented in chapter 5, Final conclusions and future scope of the proposed research are presented in the final chapter 6.
(Pl refer the original document for formulas)