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  • 401.
    Winestrand, Sandra
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Industrial applications and properties of oxalate-degrading enzymes2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Oxalate-degrading enzymes were investigated with focus on potential applications in the pulp and paper industry and in active packaging. Changes introduced to make the pulp and paper industry more environmentally friendly, such as recirculation of process-water streams and elementary chlorine free bleaching of pulp, have led to increasing problems with precipitation of calcium oxalate. The potential of using enzymes for degradation of oxalic acid in industrial bleaching filtrates was explored to find a way to decrease the problem.

    The studies included chemical characterization and enzymatic treatments of 34 filtrates from kraft, mechanical, and sulfite pulping. Eight oxalate-degrading enzymes were included in the experiments. The treatments of the filtrates were affected by substances that inhibit oxalate-degrading enzymes. Multivariate data analysis, analytical treatment of filtrates with ion-exchange resins, and analysis of the effects of separate compounds on the enzyme activity were employed as tools to investigate inhibiting substances and groups of inhibitors. The experiments with ion-exchangers indicated that the inhibitors included anions, cations, as well as uncharged substances. Sulfite (≥1 mM) caused complete or almost complete inhibition of all oxalate-degrading enzymes so far examined, while the effects of chlorine oxyanions differed for the various enzymes investigated. A newly discovered oxalate decarboxylase was chosen for experiments performed directly in a mill producing mechanical pulp. The new enzyme degraded 70% of the oxalic acid in one hour, while the well-characterized oxalate decarboxylase from Aspergillus niger degraded <5% of the oxalic acid during the same period of time.

    Oxalate decarboxylase from the white-rot basidiomycete fungus Trametes versicolor was purified by using chromatographic methods and characterized with gel electrophoresis and tandem mass spectrometry. Results indicate that it is a 69-kDa heavily glycosylated enzyme with optimal activity at pH 2.5.

    Experiments designed to investigate the potential of using oxalate oxidase from barley in active packaging showed that it could be entrapped with retained catalytic activity in a latex-polymer matrix. Furthermore, the experiments indicate that oxalate oxidase can be used in active packaging either as an oxalic acid scavenger or as an oxygen scavenger.

  • 402.
    Winestrand, Sandra
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Larsson, Simona
    Riga Technical University, Faculty of Civil Engineering, Latvia.
    Cassland, Pierre
    Applied Microbiology, Lund University/Lund Institute of Technology.
    Nilvebrant, Nils-Olof
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Jönsson, Leif J.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Effects of ionic substances in bleaching filtrates and of lignosulfonates on the activity of oxalate oxidase from barley2011Inngår i: Engineering in Life Sciences, ISSN 1618-0240, E-ISSN 1618-2863, Vol. 11, nr 3, s. 245-252Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of ionic substances in seven industrial filtrates from kraft pulping, mechanical pulping, and sulfite pulping on the activity of oxalate oxidase from barley were investigated by pre-treatment of the filtrates with ion-exchange resins prior to enzymatic degradation of the oxalic acid in the filtrates. The pre-treatment resulted in increased oxalic acid degradation rates in all filtrates, except for one that was obtained from sulfite pulping. The possibility that lignosulfonates, which were present in the filtrate from sulfite pulping, could affect oxalate oxidase was investigated in a separate set of experiments involving four different preparations of lignosulfonates. At a lignosulfonate concentration of 50 mg/mL and a pH of 3.8, only 2-16% of the activity of oxalate oxidase remained. The results show the effects of anionic and cationic substances in bleaching filtrates on oxalate oxidase and indicate that there is an interaction between the enzyme, which has a positive net charge at pH 3.8, and the polymeric anionic lignosulfonates.

  • 403.
    Winestrand, Sandra
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Latha Gandla, Madhavi
    Department of Chemistry, Umeå University.
    Hong, Feng
    College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, China.
    Chen, Qi Zhi
    College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, China.
    Jönsson, Leif J.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Oxalate decarboxylase of Trametes versicolor: biochemical characterization and performance in bleaching filtrates from the pulp and paper industry2012Inngår i: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 87, nr 11, s. 1600-1606Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: Oxalate decarboxylase (ODC) from acid-induced cultures of the white-rot fungus Trametes versicolor was purified and characterized with respect to its biochemical properties and the possibility to utilize the enzyme for treatment of process water with the intention to prevent problems with calcium-oxalate scaling in the pulp and paper industry. RESULTS: Purified T. versicolor ODC was identified by tandem mass spectrometry. As estimated by using SDS-PAGE, the molecular mass was 69 kDa, and 60 kDa after deglycosylation with N-glycosidase F. The pH optimum was 2.5 and the temperature optimum was 4045 degrees C. The effects of ten potential inhibitors in industrial filtrates were examined. The enzyme was sensitive to low concentrations (0.1 mmol L-1) of chlorite and sulfite. T. versicolor ODC exhibited activity in 16 filtrates collected from mechanical pulping and kraft pulping. It had higher activity than ODC from Aspergillus niger in all of the filtrates and higher activity than oxalate oxidase from barley in all filtrates except two. CONCLUSIONS: The investigation shows basic biochemical properties of T. versicolor ODC and indicates that the enzyme may be useful for treatment of industrial filtrates under acidic conditions. Copyright (c) 2012 Society of Chemical Industry

  • 404.
    Winestrand, Sandra
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Nilvebrant, Nils-Olof
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    The Effects of Oxyanions on the Activity of Oxalate Oxidase2009Inngår i: The Open Enzyme Inhibition Journal, ISSN 1874-9402, Vol. 2, s. 36-40Artikkel i tidsskrift (Fagfellevurdert)
  • 405. Zhen, Y.
    et al.
    Quian, J.
    Follmann, K.
    Hayward, T.
    Nilsson, Thomas
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Dahn, M.
    Hilmi, Y.
    Hamer, A.
    Hosler, J. P.
    Fergusson-Miller, S.
    Overexpression and purification of cytochrome c oxidase fromRhodobacter1998Inngår i: Protein Expression and Purification 13, 326-336Artikkel i tidsskrift (Fagfellevurdert)
  • 406.
    Åsberg, Dennis
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Enmark, Martin
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Samuelsson, Jörgen
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Fornstedt, Torgny
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    An Experimental and Theoretical investigation on Mobile PhaseEffects on Competitive Adsorption Isotherms in Preparative LC2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This poster serves as background information to the corresponding lecture. Mobile phase gradients have been used in LC since the 1950s and are still an important programming technique in both analytical and preparative LC. Improving the resolution, and thereby making the separation of complex samples possible, and reducing the separation time, which increases the productivity, are the two main advantages of gradient elution. The modelling of band profiles and the optimization of preparative separations has largely been studied under isocratic conditions. The shape of the gradient and the behaviour of the solutes are often determined experimentally with scarce knowledge about the underlying physicochemical equations. This "trial and error" approach results in time consuming and, possibly, expensive experiments. The goal of this work is to investigate the dependence of the adsorption behaviour on the mobile phase composition in reversed phase LC. By knowing the adsorption isotherm as a function of the concentrations of both the solute and the strong organic modifier, the band profiles are modelled under gradient elution conditions.Our aim is to make it possible to use modelling tools so one can optimize a separation and especially the gradient shape. Recent studies have shown that a significant improvement in productivity can be achieved if the gradient shapes are designed carefully [1,2].In this study we discuss how to obtain the adsorption isotherm data experimentally for two substances using the perturbation peak method. The substances which are investigated are cyclohexanone and cycloheptanone on a Kromasil C18-column with methanol-water as the mobile phase. The fitting of the nonlinear experimental data to appropriate theoretical isotherm models will also be discussed.For practical reasons, we will also be looking at how different key parameters, e.g. the column hold-up time, the column efficiency, the retention factor and the equilibrium constant, change with the mobile phase composition.With the experimentally determined adsorption isotherm as a basis, we will simulate overloaded band profiles under gradient elution conditions and compare the simulated results with experimentally obtained band profiles.A contribution from the Fundamental Separation Science Group www.separationscience.se

  • 407.
    Ņsberg, Dennis
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Enmark, Martin
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Samuelsson, Jörgen
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Fornstedt, Torgny
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Modelling of Overloaded Gradient Elution in Reversed-Phase Liquid Chromatography2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Mobile phase gradients have been used in LC since the 1950s and are still an important programming technique in both analytical and preparative LC. Improving the resolution, and thereby making the separation of complex samples possible - and thus reducing the separation time which increases the productivity- are the two main advantages of gradient elution. The modelling of band profiles and the optimization of preparative separations has largely been studied under isocratic conditions. The shape of the gradient and the behaviour of the solutes are often determined experimentally with scarce knowledge about the underlying physicochemical equations. This “trial and error” approach results in time consuming and, possibly, expensive experiments. The goal of this work is to investigate the dependence of the adsorption behaviour on the mobile phase composition in reversed phase LC. By knowing the adsorption isotherm as a function of the concentrations of both the solute and the strong organic modifier, the band profiles can be modelled under gradient elution conditions. Our aim is to make it possible to use modelling tools for a more reliable computer-assisted optimization, accounting for the gradient shape. Recent studies have shown that a significant improvement in productivity can be achieved if the gradient shapes are designed carefully [1,2]. In this presentation we will discuss how to obtain the adsorption isotherm data experimentally for two substances using the perturbation peak method. The substances investigated are cyclohexanone and cycloheptanone on a system comprising of a Kromasil C18-column and methanol-water as mobile phase. The fitting of the nonlinear experimental data to appropriate theoretical isotherm models will also be discussed. For practical reasons, we will also be looking at how different key parameters, e.g. the column hold-up time, the column efficiency, the retention factor and the equilibrium constant, change with the mobile phase composition. With the experimentally determined adsorption isotherm as a basis, we will simulate overloaded band profiles under gradient elution conditions and compare the simulated results with experimentally obtained band profiles. A contribution from the Fundamental Separation Science Group www.separationscience.se

  • 408. Öhman, M.
    et al.
    Wan, H.
    Blomberg, Lars G
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Hamberg, M.
    Separation of Divinyl Ether Fatty Acid Isomers by Micellar Electrokinetic Chromatography,2001Inngår i: Electrophoresis, 22 (2001) 1163-1169Artikkel i tidsskrift (Fagfellevurdert)
  • 409.
    Öhman, Marcus
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Blomberg, L.G.
    Bonded dimethylacrylamide as a permanent coating for capillary electrophoresis2001Inngår i: J. Chromatogr. A, 924 (2001) 59-70Artikkel i tidsskrift (Fagfellevurdert)
  • 410.
    Öhman, Marcus
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Wan, Hong
    Hamberg, Mats
    Blomberg, Lars G
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Separation of conjugated linoleic acid isomers and parinaric fatty acid isomers by capillary electrophoresis2002Inngår i: Journal of separation scienceArtikkel i tidsskrift (Fagfellevurdert)
  • 411.
    Öhman, Marcus
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Wan, Hong
    Hamberg, Mats
    Blomberg, Lars G.
    Separation of divinyl ether fatty acid isomers by micellar electrokinetic chromatography2001Inngår i: ElectrophoresisArtikkel i tidsskrift (Fagfellevurdert)
  • 412.
    Ölund, David
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Konstruktion av reporterplasmider innehållande möjliga promotorregioner för kloratreduktas respektive kloritdismutas från Ideonella dechloratans2012Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Ideonella dechloratans är en av flera isolerade bakteriestammar med förmågan att använda klorat i sin metabolism i anaerob miljö. Detta kan utnyttjas inom exempelvis pappersindustrin där klorat är en miljöfarlig restprodukt efter klordioxidblekning.

       Klorat och perklorat har visat sig ha negativa effekter hos både människor, djur och växter vilket ger ett stort behov av mer forskning på förbättrade reningsmetoder. Kan genregleringen av enzymerna som sköter nedbrytningen av klorat, kloratreduktas och kloritdismutas, förbättras genom att exempelvis fungera även i aerob miljö så skulle reningen förbättras samt kostnader dras ner.

       Genom att införa promotorregionerna för kloratreduktas och kloritdismutas i en broad-host-range reporterplasmid, pQlacZ-1, så kan dessa testas i flera olika förhållanden och i olika typer av gramnegativa bakterier.

       Genom dubbelklyvning av pQlacZ-1 med BamHI och EcoRI så har PCR produkter av Clrp och Cldp från Ideonella dechloratans kunnat ligeras in för att sedan transformeras in i E. coli, XL-1 Blue.    Gelextraktion har visat sig vara den effektivaste reningsmetoden inför ligering men utförligare screening behöver göras på transformanterna för att säkerställa metodens effektivitet.

6789 401 - 412 of 412
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