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  • 1.
    Agnemo, Roland
    Umeå University, Faculty of Science and Technology.
    Ligniners reaktioner med alkalisk väteperoxid1981Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Under alkaline conditions hydrogen peroxide can be used either as a 1ignin-degrading or a 1ignin-preserving bleaching agent. If heavy metal ions are present and/or silicate is absent in the reaction medium, hydrogen peroxide decomposes via hydroxyl radicals and superoxide ions to oxygen and water. These decomposition products are able to react for example with phenolic lignin structures and thereby cause a partial degradation of lignin. In such a system peroxide could act as a bleaching and delignifying agent at the same time and these properties can be utilized for the bleaching of chemical pulps.In order to elucidate the factors which influence the degradation of phenolic structures by oxidation with alkaline hydrogen peroxide the lignin model compounds-methylsyringyl alcohol was studied.By determining the first order reaction rate constants for the oxidation, the main results which were obtained indicate that phenolic lignin structures can be efficiently degraded especially if:A. The pH in the bleaching liquor is close to the pK -valueàfor hydrogen peroxide.B. The ionic strength in the bleaching medium is as high as possible.C. A fixed amount of heavy metal ions (manganese) is added to the bleaching liquor.In the presence of silicate and diethylentriaminepenta-acetic acid (DTPA) hydrogen peroxide is stabilized against decomposition. Under these conditions alkaline hydrogen peroxide is able to react only with lignin units containing conjugated carbonyl groups such as quinone, aryl-oe-carbonyl and cinnamaldehyd structures, leading to an elimination of the chromophoric structures without any substantial dissolution of lignin. In this part of work we have elucidated the kinetic behavior and the reaction products from lignin model compounds of the aryl-of- carbonyl and cinnamaldehyde types.1,2-Diarylpropan-1,3,-diol structures constitute an important building unit in native lignins. We have demonstrated that under hydrogen peroxide bleaching conditions the model compound 2,3--bis(4-hydroxy-3-methoxyphenyl)-3-ethoxy-propanol was converted to stilbenes, ûe. structures which when present in pulps may contribute to a rapid yellowing. The results obtained with model compounds under simulated lignin retaining bleaching conditions demonstrate that there are possibilities to improve the bleaching of mechanical pulps with hydrogen peroxide if:A. The remaining heavy metal ions complexed with DTPA are present in their lowest valence states.B. The concentration of hydroperoxy ions can be maintained at a high level at the lowest possible pH-value.

  • 2.
    Antonsson, Cecilia
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Mjölk, gluten och ADHD: En litteraturundersökning om mjölk och glutens påverkan hos barn med ADHD2014Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Attention Deficit Hyperactivity Disorder (ADHD) is becoming a more common diagnosis of younger children. In recent years the perception that some ingredients in our food may have a negative effect regarding the symptoms in children with ADHD has grown stronger. Children with ADHD often suffer from irritated bowel syndromes which affect their ability to digest food. This may result in malnutrition as well as a release of substances that are harmful.The purpose of this report is to compile and illustrate the knowledge of how special food, particular milk protein and gluten, may affect the symptoms of children with ADHD. Also, the report aims to evaluate if there should be changes made in Kindergarten to increase the well-being of these children. The report is a summary of research results on the effects milk protein and gluten have on children with ADHD.The majority of children with ADHD demonstrate decreased symptoms if they receive a diet without milk protein and gluten.If children with ADHD would be given a special diet excluding milk protein and gluten it is realistic to assume that their ADHD-symptoms might be reduced with a greater sense of well-being and quality of life as a result.

  • 3. Dybala-Defratyka, Agnieszka
    et al.
    Rostkowski, Michal
    Matsson, Olle
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry II. Organisk kemi.
    Westaway, Kenneth C.
    Paneth, Piotr
    A New Interpretation of Chlorine Leaving Group Kinetic Isotope Effects; A Theoretical Approach2004In: J. Org. Chem., Vol. 69, p. 4900-4905Article in journal (Refereed)
    Abstract [en]

    The chlorine leaving group kinetic isotope effects (KIEs) for the SN2 reactions between methyl chloride and a wide range of anionic, neutral, and radical anion nucleophiles were calculated in the gas phase and, in several cases, using a continuum solvent model. In contrast to the expected linear dependence of the chlorine KIEs on the Ca-CI bond order in the transition state, the KIEs fell in a very small range (1.0056-1.0091), even though the Ca-CI transition state bond orders varied widely from approximately 0.32 to 0.78, a range from reactant-like to very product-like. This renders chlorine KIEs, and possibly other leaving-group KIEs, less useful for studies of reaction mechanisms than commonly assumed. A partial explanation for this unexpected relationship between the Ca-CI transition state bond order and the magnitude of the chlorine KIE is presented.

  • 4.
    Goy, Michel
    et al.
    KTH, School of Chemical Science and Engineering (CHE).
    Jakobsson, Catharina
    KTH, School of Chemical Science and Engineering (CHE).
    Kartläggning av allergiframkallande hårfärgningsämnen i toningar i Stockholm2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    En vanlig källa till kontakallergiskt eksem är sensibiliserande (allergiframkallande) kemikalier som finns i hårfärger. Permanenta hårfärger innehåller kraftiga allergener, men det saknas kartläggande forskning på toningar. För att ta reda på vilka allergener som ingår i toningar behöver dagens utbud kartläggas. Detta projekt har skett i Stockholm och innehållet i sex olika märken har kartlagts. Toningar och permanenta hårfärger skiljer sig åt genom att permanenta hårfärger polymeriseras i håret genom oxidation med väteperoxid. Toningar innehåller kromofora ämnen som fäster i håret, antingen genom diffusion eller adsorption. Totalt kunde tio kromofora ämnen med kända sensibiliserande egenskaper hittas i toningarna varav en möjlig cancerogen. I varje produkt fanns i snitt 0,4–2,4, och som mest tre, kända sensibiliserande kromofora ämnen. Hårfärger utan sensibiliserande färgämnen kunde hittas i alla kulörer utom svart och brun. Även sensibiliserande parfymämnen och konserveringsmedel kunde påvisas. Eftersom det finns hårfärger i de flesta kulörer utan sensibiliserande färgämnen bör dessa ämnen fasas ut.

  • 5.
    Hansson, Lars
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Optimering i organisk syntes: betingelser, system, syntesvägar1990Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with different optimization problems encountered in organic synthesis. The use of response surface, sequential simplex and PLS techniques, for simultanious optimization of yield and suppression of side reactions is investigated. This is illustrated by an example of enamine synthesis, were a side reaction was a serious problem. The problem of efficient screening to find suitable catalysts and solvents in new reactions is also investigated. Here, the use of principal properties as selection criterion, is demonstrated with a new process for the silylation of a,ß-unsaturated ketones. The extension of the new method to bis silylation of 1,2- and 1,3-diketones is demonstrated. The total synthesis of (±)-geosmin is investigated by an approach aimed to reduce the number of necessary steps involved. The suggested strategy, is to find compatible solvents through several transformations in the sequence to accomplish one-pot multistep reactions. In this context an improved method for the preparation of 1,10-dimethyl-l(9)-octalone-2 was established. Comparison with previously reported total syntheses of (±)-geosmin was done. 

  • 6. Naderi, Ali
    et al.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Metod för att tillverka en vattenavvisande cellulosatextil samt motsvarande textilprodukt2011Patent (Other (popular science, discussion, etc.))
  • 7.
    Nilsson, Lars
    Umeå University, Faculty of Science and Technology.
    Enaminer och enaminoner i organisk syntes: några exempel på regiospecifika funktionaliseringar1979Doctoral thesis, comprehensive summary (Other academic)
  • 8.
    Nygren, Patrik
    Linköping University, The Department of Physics, Chemistry and Biology.
    Bioorganisk fastfas syntes för att skapa intelligenta ytor2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This thesis investigates three different surface modifications, and the route to design and synthesize them. The thesis is therefore divided into three sub- projects. (i.) Design and synthesis of a peptide which secondary structure could be controlled by a negatively charged surface. (ii.) Design and synthesis of a cyclic peptide, that would self-organize prior to surface interaction, using the type I anti-freeze protein of a winter flounder as template. (iii.) The use of solid-phase synthesis to make the synthesis of SAM-molecules easier.

  • 9.
    Zhang, Suode
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I. Avd för organisk kemi.
    Govender, Thavendran
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I. Avd för organisk kemi.
    Norström, Thomas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I. Avd för organisk kemi.
    Arvidsson, Per
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I. Avd för organisk kemi.
    An Improved Synthesis of Fmoc-N-methyl-a-amino Acids2005In: J. Org. Chem., no 70, p. 6918-6920Article in journal (Refereed)
1 - 9 of 9
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