Teses / dissertações: "Peroxides"

1

McDonald, Iain M. "Bicyclic peroxides : synthesis, structure and reactions". Thesis, Heriot-Watt University, 1987. http://hdl.handle.net/10399/1047.

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2

Gray, Norman. "The oxidation of arenethiols by peroxides". Thesis, University of Aberdeen, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328218.

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The oxidation of 4-substituted-benzenethiolate ions by hydrogen peroxide or t-butyl hydroperoxide gave the corresponding disulphide, sulphinic acid and sulphonic acid. With hydrogen peroxide the oxidation was of the second-order with p = -0.71 and showed a small positive salt effect. Benzenethiolate ion gave a small increase in rate with increasing solvent polarity and in 50% v/v dioxan at 25.0°C had ΔH^dag 54.7 kJ mol^-1, ΔS^dag -52.2 J mol^-1K^-1 and ΔG^dag 70.2 kJ mol^-1. 2-Nitrobenzenethiolate similarlygave ΔH^dag 39.7 kJ mol^-1, ΔS^dag-113.2 J mol^-1K^-1 and ΔG^dag 73.4 kJ mol^-1 and the rate was not affected by added radical traps. The oxidation of these arene-thiolate ions was entropy controlled above 255.4 K. These oxidations are proposed to be polar and to proceed initially by a nucleophilic attack of the thiolate ion on the peroxide producing a sulphenic acid intermediate. Disulphide and sulphinic acid are formed by further reaction of the sulphenic acid. Disulphides give the same products on oxidation but are not necessary intermediates. Undissociated 4-substituted-thiols give only the corresponding disulphides under these conditions. Oxidation of benzenethiolate ion with t-butyl hydroperoxide gave unusual rate curves, a negligible solvent effect and apparently a large positive ΔS^dag value. The mechanism of this oxidation differs from that previously described. 2,4-Dinitrobenzenethiolate ion gave anomalous rates of oxidation. With hydrogen peroxide (2 equivalents) the main product was the sulphinic acid, a positive salt effect was observed and excess hydroxide ion further increased the rate. The reaction may involve general base catalysis and a similar mechanism to that previously given. With t-butyl hydroperoxide (2 equivalents), less sulphinic acid was obtained together with large yields of di-(2,4-dinitrophenyl) sulphide and 2,4-dinitrophenol, presumably formed from the sulphinic acid. Added hydroxide ion markedly decreased the rate but a negative salt effect was observed. A greater difference in the mechanism is apparent in this case. The initial rate of aerial oxidation of benzenethiolate ion is of the same order of magnitude as that attributed to the medium in the peroxide oxidations and may be a radical process.

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3

Dragan, Andrei. "Oxidations with endocyclic peroxides and their derivatives". Thesis, University of Strathclyde, 2016. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27446.

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This thesis describes two novel transformations (a method to synthesize alkylidene phthalides and a different approach toward the Baeyer-Villiger oxidation) and the development and mechanistic study of a metal-free oxidation of arenes. Chapter 1 introduces the concept of alkene oxyamination. Synthesis of a series of hydroxylamine derivatives of endocyclic peroxides was undertaken, which were then reacted with nitrogen, sulfur and carbon nucleophiles. This led to the discovery of a new reaction that provides access to alkylidene phthalides, a class of compounds which exhibit interesting biological activity. Chapter 2 describes the development of an alternative approach to the Baeyer-Villiger oxidation, through the reaction of hydrogen peroxide and a nitrile in the presence of a base. Chapter 3 describes direct methods for the formation of new aromatic C–O bonds, followed by the presentation of an organic peroxide mediated approach. Herein, an examination of the mechanism of the reaction of a malonoyl peroxide with an arene is studied through Hammett analysis, isotope labeling experiments, EPR studies, DFT calculations and reactivity patterns. Chapters 4 and 5 present the experimental procedures and analytical data relevant to the three reactions developed. Chapter 6 contains a bibliography.

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4

Rawling, Michael J. "Metal-free syn-dihydroxylation of alkenes using malonoyl peroxides". Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25565.

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This thesis describes the successful application of cyclopropyl malonoyl peroxide II in the metal-free syn-dihydroxylation of alkenes I. Chapter 1 outlines the available metal-free methods for achieving syn-1,2- dioxygenation of alkenes. The use of hypervalent iodine, selenium, sulfur and peroxide reagents are discussed in terms of the advantages and limitations of each method. Chapter 2 details a mechanistic investigation into the dihydroxylation reaction using cyclopropyl malonoyl peroxide II. Through kinetic studies, Hammett analysis, multiple isotopic labelling experiments, NMR investigations and trapping experiments an ionic, stepwise mechanism has been proposed. Minor competing reaction pathways have also been identified in addition to an alternative reaction mechanism in the absence of water. Chapter 3 describes the current scope of the cyclopropyl malonoyl peroxide II mediated dihydroxylation reaction by alkene class. An application of the dihydroxylation protocol is presented in the stereoselective synthesis of a 5-deoxy-L-arabinose derivative. Interaction of cyclopropyl malonoyl peroxide II with non-alkene nucleophiles is also discussed, and a novel allylic oxidation protocol using peroxide II is introduced. Chapter 4 discusses catalysis of the dihydroxylation reaction. Alcoholic hydrogen-bond donors with a pKa of 5-8 were found to be the most effective catalysts, achieving up to 4-fold rate acceleration. Chiral hydrogen-bond catalysts are also investigated. Chapter 5 outlines the design, synthesis and reaction of chiral C2-symmetric malonoyl peroxides. The first enantioselective metal-free syn-dihydroxylation of alkenes using a peroxide reagent is reported. Chapter 6 presents preliminary investigations into a complementary antidihydroxylation protocol using cyclopropyl malonoyl peroxide II in anhydrous acetic acid.

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5

Smith, David P. "Characterisation of peracids". Thesis, University of Cambridge, 1996. https://www.repository.cam.ac.uk/handle/1810/272276.

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6

Haq, Ahsanul. "The preparation of macrocyclic compounds by thermolysis of cyclic peroxides". Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/1491.

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7

DiPasquale, Antonio Giovanni. "Peroxide complexes of non-redox active metal centers : models for alternative mechanisms in cytochrome P450 oxidations? /". Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/11603.

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8

R, Morris Vernon. "An investigation of transient atmospheric inorganic peroxides : a theoretical and experimental study". Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/25857.

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9

Tribelhorn, Michael John. "Reactions of iron- and zinc-fuelled pyrotechnic systems". Thesis, Rhodes University, 1995. http://hdl.handle.net/10962/d1005003.

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A major industrial use of pyrotechnic compositions is as delay fuses in electric detonators. Suitable delay times may be achieved through (i) choice of chemical components (ii) adjustment of composition of the system chosen and, finally, (iii) adjustment of the length of fuse used. This study forms part of a survey of binary fuel/oxidant combinations in an attempt to provide some fundamental information on the first step above: (i) choice of chemical components. The complete survey has included studies of a single fuel in combination with one of a variety of oxidants, and studies of the oxidation of one of several different fuels separately by barium peroxide and strontium peroxide. This study is part of this second approach and the fuels chosen were iron and zinc powders, mainly for chemical reasons (including the potential for use of thermomagnetometry on the iron systems), but also for possible environmental advantages. The mixed oxide products of pyrotechnic combustion could also have some scientific and/or commercial value. The techniques used included thermal analyses of mixtures and their individual components, and measurements of temperature-time profiles during combustion. Thermodynamic and kinetic information was obtained under a variety of conditions and scanning electron microscopy and X-ray diffraction and microprobe analyses provided additional information. Possible mechanisms of reactions are discussed in detail. The practical conclusions were that any potential use which the Fe/peroxide systems may have as delay compositions, with burning-rates of from 3-30 mm s⁻¹, is offset by the susceptibility of the oxidants to reaction with water and CO₂ in the atmosphere. The Zn/BaO₂ and Zn/SrO₂ systems did not burn under compaction, and combustion of uncompacted powders was erratic. Zinc liquid (and probably zinc vapour) take part in the reaction and the gaseous nature of the combustion makes zinc-fuelled pyrotechnic systems unsuitable for delay applications. All the techniques used showed the heterogeneity of the solid residues of combustion. If these residues were to be of any value, they would need further conventional treatment involving grinding of the residue, possible adjustment of compositions, and calcining to produce uniform materials.

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10

Leahy, Christopher David. "The oxidation by peroxides of cyanides, cyanide complexes and related species". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46407.

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11

Morgan, Richard Brierley. "Field studies of atmospheric peroxides and the development of sampling methods". Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410964.

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12

Stell, Jonathan Kendrew. "An E.S.R. study of the decomposition of peroxides by metal ions". Thesis, University of York, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276493.

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13

Scrivens, Garry. "An EPR investigation into the catalytic oxidation of thiols by peroxides". Thesis, University of York, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284121.

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14

Bousejra-El, Garah Fatima. "Role of metals in the mechanism of action of antimalarial peroxides". Toulouse 3, 2010. http://thesesups.ups-tlse.fr/824/.

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Le cycle 1,2,4-trioxane de l'artémisinine est essentiel pour son activité antipaludique. Le fer(II) peut catalyser la réaction de réduction de la liaison peroxyde de l'artémisinine et conduire à la formation de radicaux. Ces radicaux alkylent l'hème libéré lors de la dégradation de l'hémoglobine par Plasmodium pour former des produits de couplage appelés adduits hème-artémisinine. Ce processus d'alkylation pourrait être directement ou indirectement responsable de la mort du parasite. La connaissance du mécanisme d'action de l'artémisinine est le point de départ de ce projet de thèse qui se divise en deux parties distinctes. La première partie consiste à étudier le rôle de complexes métalliques, l'hème en particulier, dans le mécanisme d'action in vitro et in vivo de nouveaux peroxydes synthétiques ou hémi-synthétiques (artémisone, trioxaquines, trioxolanes et tétraoxanes). Nous avons caractérisé des adduits hème-drogue dans tous les cas, et confirmé l'importance de l'hème dans l'activité antipaludique de ces molécules. Une étude de docking a également été réalisée entre ces molécules et la protéine parasitaire PfATP6 présentée dans la littérature comme une autre cible de l'artémisinine. Les principaux résultats de notre étude montrent qu'il n'y a pas de corrélation entre l'affinité pour la protéine PfATP6 et l'activité in vitro des molécules testées
The 1,2,4-trioxane core structure of artemisinin is essential for its activity. It was shown that iron(II) catalyses the reductive cleavage of the peroxide bond of the drug, leading to the formation of C-centered radicals. These radicals are able to alkylate heme resulting from host cell hemoglobin digestion, and parasitic proteins. These alkylation processes are believed to induce parasite death. In the present work, we studied the two main mechanisms proposed in the literature for artemisinin, namely heme alkylation and PfATP6 inhibition. In addition, we also explored the possible bio-activation of artemisinin by copper enzymes. We report our investigation into the reactivity of metal salts and complexes, such as heme, toward highly active antimalarial peroxide-containing drugs, namely artemisone, trioxaquines, trioxolanes, and tetraoxanes. Overall, our results with heme confirmed that the alkylating properties of artemisinin, in particular in malaria-infected mice, are not limited to this natural compound, but are shared with other potent peroxide-containing drugs. It is likely that heme alkylation plays a very important role in their anti-plasmodial mechanism of action. In this work, we also considered an alternative mechanism of action for artemisinin, based on the inhibition of PfATP6. The main result is that the predicted binding affinity of the tested compounds does not correlate with their in vitro antimalarial activity

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15

Naseem, Khalid Malik. "The influence of lipoproteins and peroxides on platelet activation and inhibition". Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.718859.

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16

Fertinger, Christoph [Verfasser], e Rudi van [Akademischer Betreuer] Eldik. "Activation of Peroxides by Model Systems for Cytochrome P450 = Aktivierung von Peroxiden an Modellsystemen für Cytochrom P450 / Christoph Fertinger. Betreuer: Rudi van Eldik". Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2011. http://d-nb.info/1015475159/34.

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17

Červený, Ladislav. "Reaktivní extruze polymerů s využitím peroxidů". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-449699.

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Diploma thesis deals with processing of two types of PP, HDPE, LDPE, PET, PA, PS, PMMA and ABS by reactive extrusion in presence of peroxides. The theoretical part summarizes existing knowledge about processing of used polymers. Reactive extrusion was carried out with a single screw extruder at 260 °C, 30 rpm and 60 rpm depending on peroxide used. One type of PP was processed in presence of Luperox 101, hydrogen peroxide, dicumyl peroxide and potassium persulfate. Luperox 101 and hydrogen peroxide were chosen for reactive extrusion of other polymers. The efficiency of selected peroxides on radical modifications of individual polymers during processing was evaluated by methods of rheological (MFI), structural (FTIR) and thermal (DSC) analysis.

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18

Gerbig, Oliver [Verfasser], e Joachim [Akademischer Betreuer] Maier. "Defect chemistry in alkali peroxides and superoxides / Oliver Gerbig. Betreuer: Joachim Maier". Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2014. http://d-nb.info/1062951441/34.

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19

Khan, Mohammad A. "Thermochemical kinetic studies of organic peroxides relevant to the combustion of hydrocarbons". Thesis, University of Aberdeen, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.290241.

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In the combustion of fuels and related organic compounds the initial step consists of a free radical forming process occurring either homogeneously or heterogeneously, such as RH + O_{2 → R + HO}_2 (1) The radical R, reacts with oxygen to produce an alkyl or other peroxy radical: R + O_2 ↔ RO₂ (2) One of the controversies involved in the mechanism for the oxidation of hydrocarbons is the route for the unimolecular decomposition of the hydroperoxy alkyl radical (R_-HOOH). This would be produced as a result of the isomerisation of the alkyl peroxy radical (RO₂). There are three possible unimolecular paths for R_-HOOH together with the addition of oxygen to form hydroperoxy alkyl peroxy radical. This study is concerned with the generation of an alkyl peroxy alkyl radical and its decomposition to both epoxide and olefin formation and at lower temperatures predominantly follows the thermochemically more favourable route. No direct information is available about the rate constants of the two decomposition routes of alkyl peroxyalkyl/hydroperoxy alkyl radicals. There are different ways to find out the rate constants for the decomposition of alkyl peroxy alkyl/hydroperoxy alkyl radical to olefin and oxirane. One such way was a study of the gas phase, hydrogen chloride catalysed decomposition of di-t-butyl peroxide. A surrogate hydroperoxy alkyl radical was generated via this study and the most favourable route for the decomposition of dtBP_-H is confirmed. Again, on thermochemical grounds, the formation of isobutene oxide predominates over the formation of isobutene. The modelling of this study assisted considerably in choosing the reaction steps for a probable mechanism and in the assessment of rate parameters for the individual steps. A bonafide hydroperoxy alkyl radical was generated via the study of the sensitized decomposition of t-butyl hydroperoxide in an uncoated, coated reaction vessel and also in the presence of oxygen. The Arrhenius parameters for the ratio of the rate of formation of isobutene to isobutene oxide was observed experimentally, and are in good agreement with the estimated values in the coated reaction vessel but in uncoated and in the presence of oxygen, this ratio is nearly doubled which suggests that isobutene is formed heterogeneously and surface played an important role. In order to observe the effect of surface: volume ratio on product formation, this system was studied in four different coated reaction vessels and it was concluded that the surface effect was negligible on a coated spherical reaction vessel. The bond dissociation energy DH^o(RO-OH) in alkyl hydroperoxides, is important because the value of the rate constant is critical to cool flames production. The pyrolysis of t-butyl hydroperoxide was carried out, in a bath of isobutane in order to isolate the tBuO-OH bond breaking step. Acetone formation constituted a direct measure of the rate of decomposition of t-butyl hydroperoxide. The O-O bond dissociation energy was found experimentally, which is in good agreement with other group workers values.

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20

Pan, Yilan, e 潘怡兰. "Studies on fluorescent probes for the detection of peroxynitrite and hypochlorous acid". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45515335.

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21

Chen, Yingche, e 陈映澈. "Studies on FRET-based fluorescent probes for the detection of peroxynitrite". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46924334.

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22

Clarke, Carole Anne. "The anti-algal activity of peroxygen compounds". Thesis, University of Bath, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280884.

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23

Ennis, Julie N. "Mechanisms and applications of dioxirane chemistry". Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/33113.

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Dimethyldioxirane oxidises nitrogen-containing substrates. The sites of oxidation are generally the sp3 nitrogen atoms in the molecules although other reactive groups can be oxidised if present. An indication of the reactivity of different dioxiranes was obtained qualitatively from the polarographic peak reduction potentials and quantitatively by reaction with the model substrate 4-nitro-N,N-dimethylaniline. The polarographic peak potentials were shown to be of a similar order to those of typical acyclic peroxides. The rank order in terms of reactivity was shown to be methyl(trifluoromethyl)dioxirane > dimethyldioxirane > ethylmethyldioxirane. The rate of the reaction was not influenced by pH or ionic strength but was accelerated greatly by the presence of water. An explanation for this observation was proposed through consideration of dielectric constant and hydrogen bonding effects.

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24

Gupta, Rajat. "Is breakdown of fatty acid peroxides involved in the induction of apolipoprotein A1?" Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5752.

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Over the past few years the number of deaths caused due to cardiovascular diseases has been increasing and is of major concern. In the United States, 75% of cardiovascular-related deaths have been attributed to atherosclerosis. Western diets containing large quantities of peroxidized lipids are considered atherogenic. Heated oil in the form of fried food brings high levels of peroxidized fat and its decomposition products in the diet. Peroxidized lipids are known to increase the susceptibility of serum lipoproteins to undergo oxidation, thereby contributing to the progression of atherosclerosis. The intestinal cells are responsible for the absorption of dietary fatty acid peroxides (FAOOH) which has been reported to enhance anti-atherosclerotic effects by inducing apolipoprotein A1 (apoA1) gene and protein levels. Therefore, there is a void in the knowledge of when to expect “harmful” or “beneficial” effects of dietary lipid peroxides. The formation of toxic products like aldehydes from the decomposition of FAOOH is well documented. On the other hand, carboxylic acids particularly azelaic acid, formed as an end product of FAOOH decomposition has been reported to have anti-atherosclerotic effects. Hence, we hypothesize that intestinal cells may decompose FAOOH to aldehydes, which might get converted to carboxylic acids that can be transported across the intestine. Linoleic acid is the most abundant polyunsaturated fatty acid (PUFA) present in the diet. So, we will use peroxidized linoleic acid (13-HPODE) and incubate with intestine derived cells or Caco -2 cells as an in-vitro model for determining its decomposition to aldehydes and carboxylic acids. We propose that the decomposition products of FAOOH in the presence of intestinal cells might be responsible for causing an increase in apoA1 levels, which might suggest that lipid peroxidation derived products might actually be beneficial for reducing the progression of atherosclerosis as compared to the absorption of intact FAOOH.
M.S.
Masters
Molecular Biology and Microbiology
Medicine
Biotechnology

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25

Nissen, Jan Hendrick [Verfasser]. "Perfluorinated Dialkyl Peroxides : Their Properties And Syntheses From Perfluoroalkyl Hypohalites / Jan Hendrick Nissen". Berlin : Freie Universität Berlin, 2021. http://d-nb.info/1229436731/34.

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26

Andia, Alexander A. "Addition of Molecular Oxygen to Alkenes| Chemical and Biological Applications of Organic Peroxides". Thesis, New York University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10929113.

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Molecular oxygen is an ideal source of oxygen atoms for synthetic transformations because it is inexpensive, abundant, and non-toxic. This dissertation presents the development of synthetic methods to oxidize alkenes to α-oxygenated ketones, hydroperoxides, alcohols, and endoperoxides using molecular oxygen under transition-metal or ambient-light catalysis. Chapter One describes a copper-catalyzed method to afford α-oxygenated ketones that can be further functionalized to give a variety of products. Chapter Two offers a light-catalyzed method for the synthesis of hydroperoxides from enol ethers and strained alkenes. Chapter Three discusses a cobalt-catalyzed synthesis of 1,2-dioxolanes and their applications in cancer biology. Chapter Four presents preliminary work in the construction of 1,2-dioxanes, which can be manipulated to furnish biologically active natural product derivatives.

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27

Chung, Nga-wai. "Applications of regioselective intramolecular oxidation by dioxirane generated in situ : stereoselective synthesis of substituted tetrahydropyrans and fluorescence probes for peroxynitrite /". View the Table of Contents & Abstract, 2004. http://sunzi.lib.hku.hk/hkuto/record/B30575618.

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28

Aboua, Yapo Guillaume. "The impact of organic hydroperoxides and a red palm oil supplemented diet on spermatogenesis, sperm function and sperm apoptosis". Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/1523.

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Thesis (DTech (Biomedical Technology))--Cape Peninsula University of Technology, 2009
Many environmental, physiological, and genetic factors have been shown to impair sperm function through oxidative damage. Oxidative stress (OS) arises as a consequence of excessive reactive oxygen species (ROS) production and/or impaired antioxidant defence mechanisms. The decline in male reproductive health generated considerable public and scientific concerns about the possible role of environmental contaminants. A better understanding of how OS affects sperm function will be beneficial as it might help in the design of new and effective treatment strategies to combat the problem of increasing male subfertility. Studies have suggested that antioxidant nutrients and/or medicines play a protective role in human health. Crude red palm oil (RPO) is known to be the richest natural plant source of antioxidants such as carotenoids, tocopherols and metalloporpheryns. The aims of this study were twofold: (i) To establish an in vivo animal model of OS by exposing rat to organic hydroperoxide such as t-butyl hydroperoxide (tbHP) and cumene hydroperoxide (cHP) through repeated intraperitoneal injections that can be used for studying these effects on testicular tissue, epididymal sperm and sperm function as well as male reproductive parameters in general. (ii) To investigate the effects of a RPO supplemented diet on male reproductive parameters and tissue in animals exposed to OS. In the first part of the study, male Wistar rats aged 10-12 weeks were randomly placed in groups and received standard rat chow (SRC) and water ad lib. Animals were injected intraperitoneally with saline (0.5 ml), t-butyl hydroperoxide (5µM, 10µM, 20µM and 40µM; 0.5 ml) or cumene hydroperoxide cHP (2.5µM, 5µM, 10µM and 20µM; 0.5 ml) over a 60 day period. In the second part, male Wistar rats aged 10-12 weeks were placed randomly in three groups and fed with SRC. Group 1 received no supplement while the food of groups 2 and 3 were supplemented with 2 mL and 4 mL RPO (in 25 gm SRC/day) respectively. Each group was further divided into 3 subgroups and injected intraperitoneally daily with either saline, 10µM cHP or 20µM tbHP respectively. This was done for 5 consecutive days per week over a 60 day period. Sperm concentrations, and motility, lipid peroxidation, superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) activities as well as apoptosis were assessed.

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29

Almeida, Letícia Cunha Amaral Gonzaga de [UNESP]. "Análise do efeito clareador e da sensibilidade pós operatória utilizando diferentes materiais clareadores e fontes de luz". Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/89608.

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Made available in DSpace on 2014-06-11T19:24:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-20Bitstream added on 2014-06-13T20:11:58Z : No. of bitstreams: 1 gonzaga_lca_me_araca.pdf: 772898 bytes, checksum: a490bb43e9735c3542d945420fe1e996 (MD5)
O clareamento dental tem sido empregado por muitos profissionais por acreditarem ser uma técnica segura e eficaz. Contudo, com o objetivo de acelerar e potencializar o processo clareador, o uso de peróxidos em altas concentrações está sendo associado a fontes de calor e/ou luz. A combinação de materiais clareadores altamente concentrados com as fontes luminosas pode elevar a temperatura da estrutura dental e a penetração do peróxido, em detrimento de possíveis danos pulpares. Assim, os reais benefícios e as conseqüências biológicas desta opção de tratamento ainda são pouco conhecidos. Objetivos: comparar a efetividade clareadora, a estabilidade de cor e sensibilidade ocorridas em pacientes que receberam clareamento caseiro e de consultório com ou sem o emprego de fontes luminosas. Métodos: 40 pacientes foram selecionados e divididos aleatoriamente em quatro grupos de acordo com o tratamento clareador recebido: I- clareamento caseiro com peróxido de carbamida a 10% (PC), por 4 horas diárias, durante 3 semanas; os outros três grupos receberam 3 sessões de clareamento de consultório com peróxido de hidrogênio a 35% (PH) , com 3 aplicações de 10 minutos em cada sessão, como segue: II- sem emprego de luz, III- Lâmpada halógena, IV-LED/laser. A cor dos dentes foi avaliada utilizando a escala Vita Classical e a ocorrência de sensibilidade foi obtida por questionário feito aos pacientes, que relataram a intensidade, duração e localização da sintomatologia. As avaliações foram realizadas antes do clareamento, depois da primeira e terceira semana do clareamento com PC ou da primeira e terceira sessões de PH, bem como aos 7, 30 e 180 dias decorridos do término do tratamento. Resultados: O teste Kruskal-Wallis mostrou que a alteração de cor ocorreu de forma semelhante em todos os grupos e em todos os períodos de análise. Não foi observado retorno da cor...
The dental bleaching has been used by many professionals which believe to be a safe and effective treatment. However, to accelerate the bleaching process, the use of peroxide in high concentrations has been associated with heat or light sources. The combination of highly concentrated bleaching materials with light sources, raises the temperature of the tooth structure and penetration of peroxide which may cause pulpal damage. Thus, the real benefits and the biological consequences of this treatment are still largely unknown. Objectives: to compare the effectiveness, color stability and sensitivity occurred in patients who received at-home and in-office bleaching treatments, with or without the use of light sources. Methods: 40 patients were selected and randomly divided into four groups, according to bleaching treatment received: I- home-bleaching with 10% carbamide peroxide (CP) 4 hours/day for 3 weeks; the other three groups received 3 sessions of in-office bleaching with 35% hydrogen peroxide (HP), with 3 applications of 10 minutes in each session, as follows: II- without light source, IIIHalogen Lamp, IV-LED/laser. Tooth shade was evaluated using the Vita Classical Shade Guide before bleaching, after first and third week of at-home bleaching, after first and third session of in-office bleaching; after 1 week, 1 and 6 months after the end of the treatment. The teeth color was evaluated using the Classical Shade Guide, and the occurrence of sensitivity was obtained by questionnaire made to patients, who reported the intensity, duration and location of symptoms. The evaluations were conducted before the bleaching, after the first and third week of bleaching with PC or first and third sessions of PH and 7, 30 and 180 days after the end of treatment. Results: The Kruskal-Wallis test showed no significant differences among groups at all times (p>0.01), and there was no color rebound... (Complete abstract click electronic access below)

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Johnson, Kathryn Michelle. "A mechanistic investigation into the reaction of haem proteins with peroxides and related compounds". Thesis, University of York, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359272.

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Baker, Ruletha Deon Goodwin Douglas C. "Roles of an 'inactive' domain in catalase-peroxidase catalysis modulation of active site architecture and function by gene duplication /". Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Fall/Dissertations/HARTFIELD-BAKER_RULETNA_19.pdf.

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Chung, Nga-wai, e 鍾雅慧. "Applications of regioselective intramolecular oxidation by dioxirane generated in situ: stereoselective synthesisof substituted tetrahydropyrans and fluorescence probes forperoxynitrite". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B45014735.

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Ahn, Chang-Ho. "Mechanism of action of prostaglandin endoperoxide (U46619) and trimetoquinol on human platelet function /". The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487261553057595.

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Parsons, Jason Luke. "The mechanism of genotoxicity of potassium bromate". Thesis, University of Birmingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364521.

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Loew, Noya. "Meerrettich Peroxidase : Modifikationen und Anwendungen in Biosensoren". Phd thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2008/1843/.

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Biosensoren werden oft für die Messung einzelner Substanzen in komplexen Medien verwendet, wie z.B. bei der Blutzuckerbestimmung. Sie bestehen aus einem physikochemischen Sensor, dem Transduktionselement, und einer darauf immobilisierten biologischen Komponente, dem Erkennungselement. In dieser Arbeit wurde als Transduktionselement eine Elektrode und als Biokomponente das Enzym „Meerrettich Peroxidase“ (engl. horseradish peroxidase, HRP) verwendet. Solche HRP-Elektroden werden für die Messung von Wasserstoffperoxid (H2O2) eingesetzt. H2O2 wird im Körper von weißen Blutkörperchen produziert, um Bakterien abzutöten, wird teilweise ausgeatmet und kann in kondensierter Atemluft nachgewiesen werden. Da viele weiße Blutkörperchen bei einer Chemotherapie abgetötet und dadurch die Patienten anfälliger für Infektionen werden, muss ihre Anzahl regelmäßig überwacht werden. Dazu wird zurzeit Blut abgenommen. Im ersten Teil dieser Arbeit wurde untersucht, ob eine Überwachung der Anzahl an weißen Blutkörperchen ohne Blutabnahme durch eine H2O2-Messung erfolgen kann. Ein direkter Zusammenhang zwischen der ausgeatmeten H2O2-Menge und der Zahl der weißen Blutkörperchen konnte dabei nicht festgestellt werden. Für empfindliche H2O2-Messungen mit einer HRP-Elektrode ist ein schneller Austausch von Elektronen zwischen der Elektrode und dem Enzym notwendig. Eine Vorraussetzung dafür ist eine kurze Distanz zwischen dem aktiven Zentrum des Enzyms und der Elektrodenoberfläche. Um einen kurzen Abstand zu erreichen wurden im zweiten Teil dieser Arbeit verschiedene poröse graphitähnliche Materialien aus pyrolysierten Kobalt-Porphyrinen für die Elektrodenherstellung verwendet. Dabei stellte sich heraus, dass eines der untersuchten Materialien, welches Poren von etwa der Größe eines Enzyms hat, Elektronen etwa 200mal schneller mit dem Enzym austauscht als festes Graphit. Die HRP selbst enthält in seinem aktiven Zentrum ein Eisen-Protoporphyrin, also ein aus vier Ringen bestehendes flaches Molekül mit einem Eisenatom im Zentrum. Reagiert die HRP mit H2O2, so entzieht es dem Peroxid zwei Elektronen. Eines dieser Elektronen wird am Eisen, das andere im Ringsystem zwischengespeichert, bevor sie an ein anderes Molekül oder an die Elektrode weitergegeben werden. Im letzten Teil dieser Arbeit wurde das Eisen durch Osmium ausgetauscht. Das so veränderte Enzym entzieht Peroxiden nur noch ein Elektron. Dadurch reagiert es zwar langsamer mit Wasserstoffperoxid, dafür aber schneller mit tert-Butylhydroperoxid, einem organischen Vertreter der Peroxid-Familie.
Biosensors are often used for the measurement of specific substances in complex media, e.g. glucose in blood. They consist of a physicochemical sensor, the transducer, onto which a biological component, the recognition element, is immobilised. In this work, an electrode was used as transducer and the enzyme “horseradish peroxidase” (HRP) as biological component. Such HRP electrodes are used for the measurement of hydrogen peroxide (H2O2). H2O2 is produced in the body by white blood cells to destroy bacteria, is partially exhaled and can be measured in breath condensate. Since a lot of white blood cells are destroyed during chemotherapy and patients get more prone to infections, their amount must be checked regularly. Currently blood samples are taken for this purpose. In the first part of this work it was investigated, if the amount of white blood cells can be checked without taking blood by measuring H2O2. A correlation between the amount of exhaled H2O2 and the number of white blood cells could not be found. For a sensitive H2O2 measurement with an HRP electrode a quick exchange of electrons between electrode and enzyme is needed. One condition for this is a short distance between the active centre of the enzyme and the electrode surface. In order to achieve a short distance, several porous graphite-like materials made of pyrolysed cobalt porphyrins where used in the second part of this work for the electrode production. It turned out that one of the tested materials, which had pores about the same size as the enzyme, did exchange electrons with the enzyme about 200 times faster than solid graphite. HRP itself contains an iron protoporphyrin, i.e. a planar molecule consisting of four rings with an iron atom in the middle, its active centre. When HRP reacts with H2O2, it takes two electrons from the peroxide. One of these electrons is stored at the iron, the other in the ring system, until they are passed on to another molecule or the electrode. In the last part of this work, the iron was exchanged with osmium. The modified enzyme takes only one electron from peroxides. Thus it reacts slower with hydrogen peroxide, but faster with tert-butylhydroperoxide, an organic member of the peroxide family.

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Magagula, Sifiso Innocent. "The effect of organic peroxides on the molecular composition of heterophasic ethylene-propylene impact copolymers". Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97850.

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Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Heterophasic ethylene-propylene copolymers, also known as impact polypropylene (PP) copolymers (IPCs) or heterophasic copolymers (HECOs), are a unique group of polyolefins produced through the copolymerisation of ethylene and propylene, with the aim of improving the impact properties of the PP homopolymer at low temperatures. Therefore, this polymer comprises of a PP homopolymer matrix with a dispersed rubbery copolymer phase. Due to their unique properties, HECO polymers have become commercially important materials, with a wide range of applications. Therefore a fundamental understanding of the processes and chemistry that affects their final macroscopic properties needs to be expanded. The main focus of this investigation was to understand why specific organic peroxides influence or interact differently with the various phases of HECO polymers, in order to utilize their properties to obtain HECO polymers with optimal and desired properties. Two HECO polymers with different ethylene contents were fractionated into three fractions (30, 100 and 130 °C), using preparative temperature rising elution fractionation (P-TREF). Each individual TREF fraction was degraded with two different types of organic peroxides, and then characterised using four different analytical tools. The changes in the molecular structures of the different fractions were investigated by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The changes in comonomer sequence distributions were investigated by carbon 13 nuclear magnetic resonance spectroscopy (13C-NMR). Moreover, the degradation of the different fractions was investigated by high temperature size exclusion chromatography (HT-SEC). The investigation showed that the HECO polymers with different ethylene contents were uniquely altered. It was evident that the ethylene content influenced the degradation behaviour of the HECO polymers. The ability of the peroxide to affect certain regions of the HECO polymer more than others is highly dependent upon its miscibility with certain regions of the HECO polymers. The “visbreaking” efficiency of a specific organic peroxide appears to be primarily dependent on the number of “peroxy” groups it contains in its molecular structure. Stellenbosch University https://scholar.sun.ac.za
AFRIKAANSE OPSOMMING: Heterofase etileen-propileen ko-polimere, ook bekend as impak PP ko-polimere (IPCS) of heterofase ko-polimere (HECO), is 'n unieke groep poliolefiene geproduseer deur die ko-polimerisasie van etileen en propileen, met die doel op die verbetering in die impak eienskappe van die PP homopolimeer by lae temperature. Hierdie polimeer bestaan dus uit 'n PP homopolimeer matriks met 'n verspreide rubberagtige ko-polimeer fase. As gevolg van hul unieke eienskappe, is HECO polimere van kommersiële belang, met 'n wye verskeidenheid van toepassings. 'n Fundamentele begrip van die prosesse en chemie wat die finale makroskopiese eienskappe beïnvloed moet dus uitgebrei word. Die hooffokus van hierdie ondersoek was om te verstaan waarom spesifieke organiese peroksiede verskillende invloede en interaksies met die verskillende fases van HECO polimere het, om sodoende van hul eienskappe gebruik te maak om HECO polimere te verkry met optimale en gewenste eienskappe. Twee HECO polimere met verskillende etileen inhoud was gefraksioneer in drie fraksies (30, 100 en 130 °C), met behulp van preparatiewe temperatuur styging eluering fraksionering (P-TREF). Elke individuele TREF fraksie was gedegradeer met twee verskillende tipes organiese peroksiede en daarna gekarakteriseer deur vier verskillende analitiese metodes. Die veranderinge in molekulêre strukture van die verskillende fraksies was geondersoek met behulp van Fourier transform infrarooi spektroskopie (FTIR) en differensiële skandering kalorimetrie (DSC). Die veranderinge in ko-monomeer volgorde distribusie was bestudeer deur middel van kern magnetiese resonans spektroskopie (KMR). Verder was die degradasie van die verskillende fraksies met behulp van hoë temperatuur grootte uitsluitingschromatografie (HT-SEC) bestudeer. Die ondersoek het getoon dat die HECO polimere met verskillende etileen inhoud uniek gedegradeer was. Dus is dit duidelik genoeg dat die etileen inhoud die degradasie gedrag van die HECO polimere beïnvloed het. Die vermoë van die peroksied om sekere areas van die HECO polimeer meer as ander te beïnvloed is hoogs afhanklik van die mengbaarheid met sekere areas van die HECO polimere. Die "visbreking" doeltreffendheid van 'n spesifieke organiese peroksiede is meestal afhanklik van die aantal "peroksie" groepe in die molekulêre struktuur.

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Chaves, Tiago Alexandre Guedes. "Influência dos sistemas de luz/laser no branqueamento dentário". Master's thesis, [s.n.], 2014. http://hdl.handle.net/10284/4606.

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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária
O branqueamento dentário é um dos procedimentos cosméticos menos invasivos, com efeitos relativamente imediatos e previsíveis. Perante uma procura crescente por parte dos pacientes e uma oferta muito variada das marcas disponíveis no mercado, existem ainda poucas evidências científicas da eficácia clínica das várias técnicas, sobretudo das que recorrem ao uso de aparelhos de luz. O sucesso clínico de um branqueamento dentário depende de um correto diagnóstico da causa de alteração de cor dentária, e da maximização da eficiência da reação química dos agentes na estrutura dentária. As recentes restrições impostas pela legislação em vigor, relativas às percentagens de peróxido de hidrogénio, obrigam a uma adaptação das diferentes técnicas e materiais disponíveis. Reconhecendo todos os fatores intervenientes no branqueamento dentário, mais facilmente se poderão adaptar as técnicas executadas em consultório. Uma das opções passará pelo uso de agentes com pH mais alcalino, associada ao uso de determinadas luzes para acelerar e maximizar a reação química de branqueamento. Existem diversas fontes de luz, com características diversas e com resultados de eficácia muito distintos. O uso destes dispositivos exige um conhecimento detalhado do seu funcionamento, bem como uma elevada responsabilidade do médico dentista em garantir a segurança de todo o processo. O objetivo deste trabalho foi realizar uma revisão da bibliografia publicada sobre o papel dos diversos sistemas de luz ou de laser existentes no mercado e que podem ser usados pelo médico dentista como coadjuvantes na realização de branqueamentos dentários, descrevendo os seus mecanismos de ação, as vantagens e desvantagens do seu uso, bem como as várias indicações e contraindicações apresentadas por este tipo de tratamento. Para tal foi realizada uma pesquisa bibliográfica no período entre Novembro de 2013 e Fevereiro de 2014. A pesquisa foi baseada em informação científica devidamente publicada, realizada via online, recorrendo ao motor de busca Google, assim como às bases de dados Medline/PubMed e b-On e manualmente através de livros que abordassem o tema. As palavras-chave utilizadas na pesquisa foram : dental bleaching, teeth whitening, laser, LED, branqueamento, clareamento e peroxides. O uso de corantes, a utilização de dióxido de titânio no gel branqueador e a associação de luzes como o KTP, permitem a catalização da reação química de branqueamento, com consequente aumento da sua eficácia. Tooth bleaching is one of the least invasive cosmetic procedures, with relatively immediate and foreseeable effects. Faced with a growing demand from patients and a very varied range of brands available in the market, there is little scientific evidence for the clinical effectiveness of the various techniques, particularly those who resort to the use of light equipment. The clinical success of a dental bleaching depends on a correct diagnosis of the cause of change in tooth color, and maximizing the efficiency of the chemical reaction of the agents on tooth structure. The recent restrictions imposed by legislation in force relating to percentages of hydrogen peroxide, require an adaptation of techniques and materials available. Recognizing all the factors involved in tooth whitening, more easily can adapt the techniques implemented in practice. One of the options will by the use of agents with more alkaline pH, associated with the use of certain lights to accelerate and maximize the bleaching chemical reaction. There are several light sources with different characteristics and efficacy results very different. The use of these devices requires a detailed knowledge of its operation, as well as a high responsibility of the dentist to ensure the safety of the whole process. The objective of this study was to review the published literature on the role of various light systems or existing laser on the market that can be used by the dentist as adjuncts in performing dental bleaching, describing their mechanisms of action, the advantages and disadvantages of their use, as well as the various indications and contraindications presented by this type of treatment. For such a literature survey was conducted between November 2013 and February 2014. Research was based on published scientific information properly held online, using the Google search engine as well as the Medline / PubMed database and b- On and through books that addressed the topic. The keywords used in the search were: dental bleaching, teeth whitening, laser, LED, bleaching, bleaching and peroxides. The use of dyes, the use of titanium dioxide in the bleaching gel and the combination of KTP as the light, allow the chemical reaction of the catalyzing bleaching, with a consequent increase of efficacy.

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Hoffman, Amy Jo Gray Harry B. Hoffmann Michael R. "Photocatalytic reactions on quantum-sized semiconductor colloids : photoinitiated polymerization of vinylic monomers, formation of hydrogen peroxide and organic peroxides, oxidation of carboxylic acids, and synthesis of humic-like material /". Diss., Pasadena, Calif. : California Institute of Technology, 1993. http://resolver.caltech.edu/CaltechETD:etd-09272005-134829.

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FREITAS, ANTONIO A. de. "Recuperação de tório e terras raras via peróxido do resíduo originado na unidade de purificação de tório". reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11692.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP

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Rothbart, Sabine [Verfasser], e Rudi van [Akademischer Betreuer] Eldik. "Mechanistic investigations on the activation of peroxides by manganese compounds / Sabine Rothbart. Betreuer: Rudi van Eldik". Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2012. http://d-nb.info/1022737236/34.

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Mekarbane, Pierre Gabriel. "An ESR-spin-trapping study of radicals formed during the thermolysis of organic peroxides in solution". Thesis, Lancaster University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286991.

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Stiasny, Benedikt [Verfasser], e Thomas M. [Akademischer Betreuer] Klapötke. "Investigation of organic peroxides and their properties as energetic materials / Benedikt Stiasny ; Betreuer: Thomas M. Klapötke". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/1151449148/34.

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Shields, Dylan J. "Photochemistry of Organic Azides, Quinones, and Peroxides in Solution, Crystals, Super Molecular Complexes and Cryogenic Matrices". University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin157441745178423.

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Gulzar, Naeem [Verfasser], e Martin [Akademischer Betreuer] Klußmann. "C–H Functionalization Via Photochemically Generated Peroxides: Method Development and Mechanistic Studies / Naeem Gulzar. Gutachter: Martin Klußmann". Köln : Universitäts- und Stadtbibliothek Köln, 2014. http://d-nb.info/1064693385/34.

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Bråred, Christensson Johanna. "Clinical and experimental studies on oxidized fragrance terpenes as contact allergens /". Göteborg : Department of Dermatology and Venereology, Sahlgrenska University Hospital, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, 2009. http://hdl.handle.net/2077/19052.

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Kozak, Allyson Jill. "The balance of nitric oxide and peroxynitrite in the heart during organ preservation". View abstract, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3295438.

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Mohd, Esah Effarizah. "The effect of metal peroxides on the survival of campylobacter jejuni and the role of CorA in magnesium uptake". Thesis, University of Surrey, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604031.

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The initial aim of this study was to investigate the potential of oxygen releasing compounds as an antimicrobial treatment to reduce the transmission of C. jejuni. C. jejuni was highly sensitive to Mg02 Ca02 and 2Na2CO3H202 when exposed to these compounds in Maximum Recovery Diluent (MRD), Ultra Heat Treated (UHT) skimmed milk and soil microcosms. in MRD, initial counts of 1 x 107 colony forming units per ml fell to undetectable levels in 32, 8 and 4 hours in the presence of 0.26, 2.6 and 5.2 mM Mg02 respectively. The same reduction in viability of C. jejuni was seen within 10 minutes and 30 minutes in the presence of 5.2 mM, 2.6 mM and CaO2 respectively. When C.jejuni cells were exposed to 2.6 mM -and 5.2 mM 2NazCO).31-hCh. viable counts fell by 7-logs in 15 minutes. The survival of C. jejuni when exposed to I-h02 was similar to that seen with Mg02 but when catalase was added, Mg02 had little impact on C. jejuni killing, suggesting that H20 2 formation via this metal peroxide is important in the killing process . Electron microscope observaltions revealed an irregular cell morphology and loss of cell wall integrity as well as loss of polar flagella. Cork (Cj0726C), the main magnesium transporter of C. jejuni, was inactivated by allelic exchange to determine whether magnesium transport was necessary for the oxidative killing seen with magnesium peroxide. The corA mutant did not grow without Mg2+ suppIementation (20 mM), indicating that Mg2+ acquisition by corA is essential for C.jeuni growth in vitro that might be important in adaptation to low-Mg2+ conditions. However, CorA was not essential in magnesium peroxide killing. Whilst a corA mutant showed a reduced ability to kill the larvae of Galleria mellonella, CorA did not appear to be required for chicken colonisation by oral gavage or for intracellular survival within Caco-2 cells

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Ma, Kangming 1965. "Peroxide value and trans analyses by Fourier transform infrared (FTIR) spectroscopy". Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36643.

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New Fourier transform infrared (FTIR) approaches for the quantitative determination of peroxide value (PV) and isolated trans analyses were investigated and developed. The FTIR-PV methods investigated were all based on the stoichiometric reaction of hydroperoxides and triphenylphosphine (TPP) which converts TPP to triphenylphosphine oxide (TPPO). A reference transmission cell (100 mum) method was developed based on the use of a unique TPPO absorption at 542 cm-1. This method covered PV values from 0--15 PV and was shown to be superior in accuracy and reproducibility to the standard American Oil Chemists Society (AOCS) iodometric method. Subsequently, the utility of disposable polyethylene cards, normally used only for qualitative analyses, was investigated for quantitative PV determination. A quantitative IR card method was successfully developed and shown to serve as a very simple, rapid and alternative means of carrying out PV analyses. TPP-impregnated cards were able to reproduce the transmission cell PV results to +/-1.12 PV, while the unimpregnated card was slightly more accurate (+/-0.92 PV). A third FTIR-PV method was developed specifically for the at-line monitoring of high PV fatliquors and employed a germanium attenuated total reflectance sample handling accessory. This method hinged on the use of a TPPO absorption band at 1118 cm-1, normally off scale when pathlengths of >3 mum are used, but is suited to the analysis of oils having very high PVs (>250). The successful quantitative use of the disposable polyethylene IR card to PV led to its study for the quantitative FTIR determination of the isolated trans content of fats and oils and margarines. The polyethylene card was shown to unique and useful properties, tending to inhibit fat crystallization and its inability to retain moisture. These two properties allowed trans determination to be carried out on melted, high trans fats, without heating the polyethylene substrate and also to analyze margarines

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Ticha, Lawrence Awa. "Development of amperometric biosensor with cyclopentadienylruthenium (II) thiolato schiff base self-assembled monolayer (SAM) on gold". Thesis, University of the Western Cape, 2007. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5394_1341319478.

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A novel cyclopentadienylruthenium(II) thiolato Schiff base, [Ru(SC6H4NC(H)C6H4OCH2CH2SMe)(&eta
5-C2H5]2 was synthesized and deposited as a selfassembled monolayer (SAM) on a gold electrode. Effective electronic communication between the Ru(II) centers and the gold electrode was established by electrostatically cycling the Shiff base-doped gold electrode in 0.1 M NaOH from -200 mV to +600 mV. The SAMmodified gold electrode (Au/SAM) exhibited quasi-reversible electrochemistry. The integrity of this electro-catalytic SAM, with respect to its ability to block and electro-catalyze certain Faradaic processes, was interrogated using Cyclic and Osteryoung Square Wave voltammetric experiments. The formal potential, E0', varied with pH to give a slope of about - 34 mV pH-1. The surface concentration, &Gamma
, of the ruthenium redox centers was found to be 1.591 x 10-11 mol cm-2. By electrostatically doping the Au/SAM/Horseradish peroxidase at an applied potential of +700 mV vs Ag/AgCl, a biosensor was produced for the amperometric analysis of hydrogen peroxide, cumene hydroperoxide and tert-butylhydroperoxide. The electrocatalytic-type biosensors displayed typical Michaelis-Menten kinetics with their limits of detection of 6.45 &mu
M, 6.92 &mu
M and 7.01 &mu
M for hydrogen peroxide, cumene hydroperoxide and tert-butylhydroperoxide respectively.

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50

Dubois, Janie. "Determination of peroxide value and anisidine value using Fourier transform infrared spectroscopy". Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23391.

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Resumo:

Lipid oxidation has important consequences in the edible oil industry, producing compounds with sensory impact and thus reducing the economic value of the products. This work focused on the development of two Fourier transform infrared (FTIR) spectroscopy methods for the measurement of peroxide value (PV) and anisidine value (AV), representing the primary and secondary oxidation products of edible oils.
The infrared method developed for PV determination was based on a mathematical treatment by the partial least squares method of the information contained in the spectral region between 3750 and 3150 cm$ sp{-1}$.
The second method developed considered aldehyde content and anisidine value, a measure of secondary oxidation products.
The two methods developed are rapid ($ sim$2 min/sample) and have the advantage of being automatable. An infrared system coupled to a computer can collect the spectrum of an oil, analyze it and present a report without the need for personnel trained in FTIR spectroscopy. The cost of such a system would rapidly be absorbed through savings on personnel cost, time and chemical reagents required for conventional chemical methods and as such provides a useful advance in quality control methodology for the edible oils sector. (Abstract shortened by UMI.)

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