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  • 301.
    Helleblad, Thérese
    Karlstad University, Faculty of Technology and Science.
    Kemi ur förskolebarns perspektiv: En studie i barns uppfattningar om kemi2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 302.
    Henriksson, Gunnar
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    What are the biological functions of lignin and its complexation with carbohydrates?2017In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 4, p. 527-541Article in journal (Refereed)
    Abstract [en]

    This critical review discusses how lignin can fulfill its biological functions with a focus on the potential importance of covalent bonds between lignin and polysaccharides. Biological function and definition of lignin are discussed. There are several direct and indirect indications that covalent bonds between lignin and polysaccharides are common in wood, and there are mechanistic explanations for the formation of these bonds, with the exception of phenyl glycosides. Grasses might have a unique pathway for formation of links between lignin and hemicellulose. The monolignol structures might be evolutionary "designed" for forming covalent bond to polysaccharides during polymerization, and hemicelluloses might have the ability to some extent control the lignin structure and frequency of covalent bonds between lignin and polysaccharides. These bonds represent both technical problems and possibilities.

  • 303.
    Hermans, Bart
    et al.
    Belgien.
    De Schryver, Frans C.
    Belgien.
    van Stam, Jan
    Belgien.
    Boens, Noel
    Belgien.
    Jérôme, Robert
    Belgien.
    Teyssié, Philippe
    Belgien.
    Trossaert, Geert
    Belgien.
    Goethals, Erik
    Belgien.
    Schacht, Etienne
    Belgien.
    Global Compartmental Analysis of the Fluorescence Decay Surface of the Halato Telechelic Polymer (N,N-dimethyl-N-[3-(1-pyrenyl)propyl]ammonio)-trifluoromethane-sulfonate-End-Capped Poly(tetrahydrofuran)1995In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 28, p. 3380-3386Article in journal (Refereed)
  • 304. Hermans, E
    et al.
    De Schryver, FC
    Bhaskar Dutt, G
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    De Feyter, S
    Boens, N
    Miller, RD
    Global compartmental analysis of the fluorescence decay surface of intramolecular chain mediated and through space excited-state complex formation of a silane linked donor-acceptor system1996In: New J. Chem., 1996, 20, 829-838Article in journal (Refereed)
  • 305.
    Hernandez, Victor Agmo
    et al.
    Uppsala University, Sweden.
    Samuelsson, Jorgen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Forssen, Patrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Fornstedt, Torgny
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences. Uppsala University, Sweden.
    Enhanced interpretation of adsorption data generated by liquid chromatography and by modern biosensors2013In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1317, p. 22-31Article in journal (Refereed)
    Abstract [en]

    In this study we demonstrate the importance of proper data processing in adsorption isotherm estimations. This was done by investigating and reprocessing data from five cases on two closely related platforms: liquid chromatography (LC) and biosensors. The previously acquired adsorption data were reevaluated and reprocessed using a three-step numerical procedure: (i) preprocessing of adsorption data, (ii) adsorption data analysis and (iii) final rival model fit. For each case, we will discuss what we really measure and what additional information can be obtained by numerical processing of the data. These cases clearly demonstrate that numerical processing of LC and biosensor data can be used to gain deeper understanding of molecular interactions with adsorption media. This is important because adsorption data, especially from biosensors, is often processed using old and simplified methods. (C) 2013 Elsevier B.V. All rights reserved.

  • 306.
    Hillerström, Anna
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Effect of solvents during material treatment applications: tuning hydrophilicity of silicone rubber and drug loading in mesoporous silica2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Choosing the right solvent is critical for many industrial applications. A useful property for selection of solvents is their solubility parameters. This concept of solubility parameters is central to this thesis and has been used in two different case studies of material treatment applications.

    Silicone rubber (crosslinked poly(dimethyl siloxane), PDMS) has many favorable material properties making it useful in biomedical devices. However, a limiting aspect of its material properties is a hydrophobic surface. The aim of this work was to prepare a hydrophilic PDMS material while retaining the transparency of the material. To do this, PDMS was combined with a hydrophilic polymer, polyvinylpyrrolidone (PVP) in an interpenetrating polymer network (IPN). A two-step IPN synthesis method was developed and it was found that the solvent used for polymerization of PVP had a significant influence on the water-wettability and the transparency of the PVP/PDMS IPN. Several different analytical techniques were used for determining the degree of phase separation in the PVP/PDMS IPN. It was found, by using microscopy techniques, that the PVP phase domains varied between 200 nm up to a few micrometers, and the size of the phase domains was correlated to the solvent used for polymerization of the IPN.

    The second topic for which solvent effects were explored was for the use of mesoporous silica particles as potential drug delivery devices. In the present work a drug molecule, ibuprofen, was loaded into mesoporous silica particles using different solvents, and in addition adsorption isotherms were established in each solvent. The maximum loading of ibuprofen in the mesoporous material was achieved when using a nonpolar solvent, in particular liquid carbon dioxide was successfully used. One of the advantages of using liquid carbon dioxide is that no solvent residues are left in the final material, which is important for pharmaceutical applications. Furthermore, it was concluded that ibuprofen was stored in an X-ray amorphous form in the mesoporous particles. Release studies in water showed a rapid release of ibuprofen from the mesoporous silica particles, while the dissolution of samples with crystalline ibuprofen was slower. This was verified to be an effect of a larger exposed ibuprofen area in the ibuprofen-loaded mesoporous silica particles, and it was concluded that the intrinsic dissolution rate for the samples were identical.

  • 307.
    Hillerström, Anna
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Andersson, Martin
    YKI, Institute of Surface Chemistry, Stockholm.
    Jan, Skov Pedersen
    University of Aarhus.
    Altskär, Annika
    SIK, The Swedish Institute for Food and Biotechnology, Göteborg.
    Langton, Maud
    SIK, The Swedish Institute for Food and Biotechnology, Göteborg.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Kronberg, Bengt
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Transparency and Wettability of PVD/PDMS-IPN Synthesized in Different Organic Solvents2009In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 114, no 3, p. 1828-1839Article in journal (Refereed)
  • 308.
    Hillerström, Anna
    et al.
    Technical Research Institute of Sweden, Box 5607, SE-114 86 Stockholm, Sweden.
    Andersson, Martin
    Technical Research Institute of Sweden, Box 5607, SE-114 86 Stockholm, Sweden.
    Samuelsson, Jörgen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    van Stam, Jan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Solvent strategies for loading and release in mesoporous silica2014In: Colloid and Interface Science Communications, ISSN 2215-0382, Vol. 3, p. 5-8Article in journal (Refereed)
    Abstract [en]

    A model molecule, ibuprofen, was loaded in the pores of mesoporous silica by adsorption from nonpolar solvents (liquid carbon dioxide and cyclohexane) and from a polar solvent (methanol). It was sufficient with a very low concentration of ibuprofen in the nonpolar solvents to achieve maximum loading of ibuprofen in the mesoporous particles. When using liquid carbon dioxide, the pores of the mesoporous silica particles were filled completely with ibuprofen at a lower ibuprofen concentration than similar experiments performed with cyclohexane. When methanol was used, the maximum amount of loaded ibuprofen was never achieved. Furthermore, x-ray scattering showed that all ibuprofen loaded into the mesoporous particles were in an amorphous state. Ibuprofen was released from the mesoporous particles to water within a couple of minutes, regardless of solvent used for loading. It was found that the release of ibuprofen from mesoporous silica was much faster than that of crystalline ibuprofen.

  • 309.
    Hillerström, Anna
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Kronberg, Bengt
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    A Two-Step method for the Synthesis of a Hydrophilic PDMS Interpenetrating Polymer Network2008In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 110, no 5, p. 3059-3067Article in journal (Refereed)
    Abstract [en]

    A hydrophilic PDMS (polydimethylsiloxane) surface was formed by the synthesis of an interpenetrating polymer network (IPN) in a two-step process. In the first step, PDMS was loaded with crosslinker and initiator using a solvent that swells the PDMS. In the second step, the PDMS sample was submerged into a solution containing the hydrophilic monomer followed by a UV-polymerization step. The choice of solvent in the second step is critical to obtain a hydrophilic surface. It can be concluded that the solubility parameter of the solvent should be above a threshold value. Hence, in the second step only sufficiently polar solvents will result in hydrophilic PDMS-IPNs. These principles are illustrated by using N-vinyl-2-pyrrolidone as the hydrophilic monomer forming PVP/PDMS-IPNs.

  • 310.
    Hillerström, Anna
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Andersson, Martin
    YKI, Institute for Surface Chemistry, Stockholm.
    Ibuprofen Loading into Mesostructured Silica using Liquid Carbon Dioxide as a Solvent2009In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 11, no 5, p. 662-667Article in journal (Refereed)
  • 311.
    Hillerström, Anna
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Andersson, Martin
    YKI, Institute for Surface Chemsitry, Stockholm.
    Strategies for obtaining High Enrichment of ibuprofen in Mesoporous Silica, the Effect of Solvent Type, and Release KineticsManuscript (preprint) (Other academic)
  • 312. Hirota, S.
    et al.
    Svensson, M.
    Ädelrot, P.
    Sone, N.
    Nilsson, Thomas
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Malmström, B.G.
    Brzesinski, P.
    A flash-photolysis study of the reactions of a caa3-type cytochrome oxidase with dioxygen and carbon monoxide1996In: J. Bioenergetics and Biomembranes, 28 , 495-501Article in journal (Refereed)
  • 313.
    Hoang, Xuan Huyen Trang
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Sample preparation and calibration in chromatographic analysis of natural products2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Gas chromatography and high performance liquid chromatography are common techniques to analyse many type of samples. Sample preparation is the first step and play an important role in the process of quantitative analysis. Sample preparation can have a major effect in the overall accuracy and reliability of the results. The aim of this step is to provide a sample aliquot that will not damage the column or instrument, have appropriate concentration, and is compatible with the intended analytical method. In the process of sample preparation and analysis, different errors may influence the results. Internal standards are usually used to limit these errors. The data in report I and II shows that the internal standard has helped to reduce errors due to sample preparation and the factors affecting results such as variations in injection volumes, evaporation of solvent and instability in detection.

  • 314.
    Holmberg, Filippa
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Department of Educational Studies (from 2013).
    De yngsta barnens språkutveckling relaterat till vattnets faser: En observationsstudie om hur barns språk kopplat till vattnets aggregationsformer kan förändras genom aktiviteter relaterade till lärandeobjektet.2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to define children’s transformation of language when exploring the aggregational states of water. The theoretical frame is the socio-cultural perspective and phenomenography. The study is an observational study based on children’s participation in experiments and reflective conversations, all lead by pre-school teachers. Two separate groups of children have been observed for one day each when participating in the same experiment at two different times, to be able to tell if any difference in their perception and language can be seen through activities related to the object of learning. Reflective conversations have been held in between the experiments to give the children the opportunity to discuss what they experienced. Nine children at the age of two to three years old has been part of the study. The result of the study shows a change in children’s language. Words and concepts they have learned helps them to an increased understanding of their surroundings and the specific phenomenon, the aggregational states of water. Molecules, temperature, solid form, liquid form, gaseous form are words that the children noticed and used according to the result. The result also indicates that an interaction between children can generate an increased vocabulary. Preschool teachers' guiding questions and co-research also proved to support children's language development.

  • 315.
    Holmes, Natalie P.
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). University of Newcastle, Australia.
    Marks, Melissa
    University of Newcastle, Australia.
    Cave, James M.
    University of Bath, United Kingdom.
    Feron, Krishna
    University of Newcastle, Australia.
    Barr, Matthew G.
    University of Newcastle, Australia.
    Fahy, Adam
    University of Newcastle, Australia.
    Sharma, Anirudh
    Flinders University, Australia; University of Bordeaux, France.
    Pan, Xun
    Flinders University, Australia.
    Kilcoyne, David A. L.
    Lawrence Berkeley National Laboratory, United States.
    Zhou, Xiaojing
    University of Newcastle, Australia.
    Lewis, David A.
    Flinders University, Australia.
    Andersson, Mats R.
    Flinders University, Australia.
    van Stam, Jan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Walker, Alison B.
    University of Bath, United Kingdom.
    Moons, Ellen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Belcher, Warwick J.
    University of Newcastle, Australia.
    Dastoor, Paul C.
    University of Newcastle, Australia.
    Engineering Two-Phase and Three-Phase Microstructures from Water-Based Dispersions of Nanoparticles for Eco-Friendly Polymer Solar Cell Applications2018In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 30, no 18, p. 6521-6531Article in journal (Refereed)
    Abstract [en]

    Nanoparticle organic photovoltaics, a subfield of organic photovoltaics (OPV), has attracted increasing interest in recent years due to the eco-friendly fabrication of solar modules afforded by colloidal ink technology. Importantly, using this approach it is now possible to engineer the microstructure of the light absorbing/charge generating layer of organic photovoltaics; decoupling film morphology from film deposition. In this study, single-component nanoparticles of poly(3-hexylthiophene) (P3HT) and phenyl-C61 butyric acid methyl ester (PC61BM) were synthesized and used to generate a two-phase microstructure with control over domain size prior to film deposition. Scanning transmission X-ray microscopy (STXM) and electron microscopy were used to characterize the thin film morphology. Uniquely, the measured microstructure was a direct input for a nanoscopic kinetic Monte Carlo (KMC) model allowing us to assess exciton transport properties that are experimentally inaccessible in these single-component particles. Photoluminescence, UV-vis spectroscopy measurements, and KMC results of the nanoparticle thin films enabled the calculation of an experimental exciton dissociation efficiency (ηED) of 37% for the two-phase microstructure. The glass transition temperature (Tg) of the materials was characterized with dynamic mechanical thermal analysis (DMTA) and thermal annealing led to an increase in ηED to 64% due to an increase in donor-acceptor interfaces in the thin film from both sintering of neighboring opposite-type particles in addition to the generation of a third mixed phase from diffusion of PC61BM into amorphous P3HT domains. As such, this study demonstrates the higher level of control over donor-acceptor film morphology enabled by customizing nanoparticulate colloidal inks, where the optimal three-phase film morphology for an OPV photoactive layer can be designed and engineered.

  • 316.
    Holmes, Natalie P.
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). University of Newcastle, Australia.
    Munday, Holly
    University of Newcastle, Australia.
    Barr, Matthew G.
    University of Newcastle, Australia.
    Thomsen, Lars
    Australian Synchrotron, Australia.
    Marcus, Matthew A.
    Lawrence Berkeley National Laboratory, USA.
    Kilcoyne, A. L. David
    Lawrence Berkeley National Laboratory, USA.
    Fahy, Adam
    University of Newcastle, Australia.
    van Stam, Jan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Dastoor, Paul C.
    University of Newcastle, Australia.
    Moons, Ellen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Unravelling donor–acceptor film morphologyformation for environmentally-friendly OPV inkformulations2019In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270Article in journal (Refereed)
    Abstract [en]

    The challenge of coating organic photovoltaics (OPV) from green solvents is to achieve the requirednanostructured interpenetrating network of donor and acceptor domains based on a rational choice ofsolvent approach as opposed to the usual trial-and-error methods. We demonstrate here that we canachieve a bicontinuous interpenetrating network with nanoscale phase separation for the chosen donor–acceptor material system poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl]:phenyl-C61 butyric acid methyl ester (TQ1:PC61BM) when processing from green solvent ink formulations.This structure is achieved by first calculating the Hansen solubility parameters (HSP) of the donor andacceptor materials, followed by careful choice of solvents with selective relative solubilities for the twomaterials based on the desired order of precipitation necessary for forming a nanostructured interdigitatednetwork morphology. We found that the relative distances in Hansen space (Ra) between TQ1 andthe primary solvent, on the one hand, and PC61BM and the primary solvent, on the other hand, could becorrelated to the donor–acceptor morphology for the formulations based on the solvents d-limonene,anisole, and 2-methyl anisole, as well as the halogenated reference solvent o-dichlorobenzene. Thisnanostructured blend film morphology was characterised with scanning transmission X-ray microscopy(STXM) and transmission electron microscopy (TEM), and the film surface composition was analysed bynear edge X-ray absorption fine structure (NEXAFS) spectroscopy. Hansen solubility theory, based onsolution thermodynamics, has been used and we propose an HSP-based method that is a general platformfor the rational design of ink formulations for solution-based organic electronics, in particular facilitatingthe green solvent transition of organic photovoltaics. Our results show that the bulk heterojunctionmorphology for a donor–acceptor system processed from customised solvent mixtures can be predictedby the HSP-based method with good reliability.

  • 317. Hong, F.
    et al.
    Jönsson, Leif J
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre.
    Lundquist, K.
    Wei, Y.
    Oxidation capacity of laccases and peroxidases as reflected in experiments with methoxy-substituted benzyl alcohols2006In: Appl. Biochem. Biotechnol. (2006) 129, 303-319Article in journal (Refereed)
  • 318. Hong, F.
    et al.
    Meinander, N.
    Jönsson, Leif J
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre.
    Fermentation strategies for improved heterologous expression of laccase in Pichia pastoris2002In: Biotech. Bioeng. (2002) 79, 438-449Article in journal (Refereed)
  • 319. Hong, F.
    et al.
    Nilvebrant, N.-O.
    Jönsson, Leif J
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre.
    Rapid and convenient determination of oxalic acid employing a novel oxalate biosensor based on oxalate oxidase and SIRE technology2003In: Biosens. Bioelectron. (2003) 18, 1173-1181Article in journal (Refereed)
  • 320. Hull, Angelica
    et al.
    Golubkov, I.
    Kronberg, Bengt
    Marandzheva, T.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    An Alternative Fuel for a Standard Spark Ignition Engine2006In: Int. J. Engine Res., 2006, 7, 203-214Article in journal (Refereed)
  • 321. Hull, Angelica
    et al.
    Golubkov, I.
    Kronberg, Bengt
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Alternative Fuel for a Standard Diesel Engine2006In: Int. J. Engine Res., 2006, 7, 51-64Article in journal (Refereed)
  • 322. Hull, Angelica
    et al.
    Kronberg, Bengt
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Golubkov, I
    Kristensson, J
    Vapour-Liquid Equilibrium of Binary Mixtures. Part I; ethanol+1-butanol, ethanol + octane, 1-butanol+octane2006In: J. Chem. Eng. Data, 2006, 51, 1996-2001Article in journal (Refereed)
  • 323. Hull, Angelica
    et al.
    Kronberg, Bengt
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Golubkov, I
    Kristensson, J
    Vapour-Liquid Equilibrium of Binary Mixtures. Part II; ethanol+2,2,4-trimethyl pentane, 1-butanol+2,2,4-trimethyl pentane, ethanol+o-xylene2006In: J. Chem. Eng. Data, 2006, 51, 2002-2008Article in journal (Refereed)
  • 324.
    Hussain, Arif
    Karlstad University, Faculty of Technology and Science.
    Adsorption of Polyvinyl Alcohol on Nano-Cellulose Fibers2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nano-cellulose fibers/suspension has very high viscosity, its viscosity has to be lower before it can be applied in the paper coating recipe. For this purpose the adsorption behaviour of polyvinyl alcohol on nano-cellulose fibers were investigated using method developed by Zwick in 1960, based on the formation of PVA-iodide blue complex in the presence of boric acid. The experiments showed that the maximum adsorbed amount i.e. 0.13 g PVA/g NFC was obtained in a dispersion with 0.2 % PVA concentration. It should be possible to further increase the PVA adsorption as the adsorbed amount didn’t reach a saturation point where the PVA adsorption attained a constant value. It was also found that adsorption of PVA on NFC is time dependent. The absorbance measurement after four days of mixing PVA/NFC suspension showed only partially adsorption of PVA on nano-cellulose surface.  An equilibrium time of 10-13 days was needed for PVA to fully adsorb on nano-cellulose fibers surface. Another important observation was that PVA adsorption also depends on the concentration of nano-cellulose fibers. A lower concentration of NFC easily allows PVA to adsorb on its surface, as compared to higher NFC concentration. An important finding during the methodology development was the method to get rid of formation of flocs in the blue iodide complex solution; by slowly addition of reactants, especially the KI/I2 solution under continuous stirring around 60oC the tendency to flocs formation was suppressed.

  • 325.
    Hårdfelt, Louise
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Department of Educational Studies.
    Återvinning och återanvändning i förskolan: En studie om hur olika förskolor arbetar med återvinning och återanvändning av material tillsammans med barnen2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 326.
    Höglund, Elisabeth
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    En jämförelse mellan industriellt och laborativt kokad pappersmassa med olika analytiska metoder: - innefattande utformning av en metod för enzymatisk nedbrytning av massafibrer2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The properties of industrially produced pulp and corresponding cooked pulp devised in the laboratory were studied during the first part of this project. The industrial pulp proved to have a lower surface charge compared to the laboratory-cooked pulp, while similar results were obtained during total charge analysis. Regarding properties such as fiber width and fiber length, no major differences between the pulps were found, and during the analysis of the total content of individual monosaccharides, only the amount of xylose differed showing a slightly lower amount for the laboratory-cooked pulp. Part two of the project included a method formation for analyzing the carbohydrate composition on the surface of pulp fibers. The sample containing polysaccharides was hydrolyzed with a mixture of cellulase and hemicellulase which resulted in gradual fiber peeling. The method itself may in fact need further development, but overall the test generated a positive outcome. To desalinate and lower the content of sugars within the enzyme mix before hydrolysis along with using calibration solutions containing enzymes were shown to be important factors in retaining optimal results.

  • 327.
    Höglund, Elisabeth
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Production of Dialdehyde Cellulose and Periodate Regeneration: Towards feasible oxidation processes2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cellulose is an attractive raw material that has lately become more interesting thanks to its degradability and renewability and the environmental awareness of our society. With the intention to find new material properties and applications, studies on cellulose derivatization have increased. Dialdehyde cellulose (DAC) is a derivative that is produced by selective cleavage of the C2-C3 bond in an anhydroglucose unit in the cellulose chain, utilizing sodium periodate (NaIO4) that works as a strong oxidant. At a fixed temperature, the reaction time as well as the amount of added periodate affect the resulting aldehyde content. DAC has shown to have promising properties, and by disintegrating the dialdehyde fibers into fibrils, thin films with extraordinary oxygen barrier at high humidity can be achieved. Normally, barrier properties of polysccharide films deteriorate at higher humidity due to their hygroscopic character. This DAC barrier could therefore be a potential environmentally-friendly replacement for aluminum which is utilized in many food packages today.

    The aim of this study was to investigate the possibilities to produce dialdehyde cellulose at an industrial level, where the regeneration of consumed periodate plays a significant role to obtain a feasible process. A screening of the periodate oxidation of cellulose containing seven experiments was conducted by employing the program MODDE for experimental design. The reaction time was varied between 2-8 hours and the ratio NaIO4 to fiber in was between 1-2 (w/w) for small-scale experiments (1 g fiber), which resulted in an aldehyde content between 14-80 %. An oxidation degree around 30 % was set as a goal, and the optimal point at a fixed temperature of 50°C was assessed to be a ratio of 1.5 and a reaction time of 2.5 h, including 30 min of cooling. Furthermore, the MODDE evaluation suggested that the time and quantity of added periodate equally effected the reaction. An up-scaling of the system with 22.5 g of NaIO4 and 15 g of cellulose fibers and a total reaction time of 3h, resulted in 39 % oxidation degree and a yield of 92 %.

    For the regeneration of periodate, Oxone® was tested, but too low yields were obtained. More studies are needed in order to understand and optimize this process. Better results where gained when utilizing a 10 % hypochlorite solution (NaOCl) that was refluxed with the filtrate from the periodate oxidation of cellulose. A spectrophotometric method was developed to be able to quantify the amount of periodate and thereby the amount of residual iodate (IO3-), i.e. the byproduct to oxidize back to IO4-. An optimization study was performed with eleven experiments with the time varying between 1-4 hours and the molar ratio of NaOCl to IO3- between 1-4. However, it was found that the residual periodate also consumed the hypochlorite, so the real molar ratio of NaOCl to IO3- and IO4- was only 0.38-1.52. The highest ratio of 1.52 with a reaction time of 4 h generated the highest regeneration of 81 %. From the MODDE evaluation it was suggested that the reaction time does not have as significant effect upon the process as the amount of added NaOCl has. By optimizing this reaction further, it should be possible to reach even more satisfying results. However, it was proved that the precipitated product was sodium paraperiodate, Na3H2IO6, and this regenerated product was successfully used to oxidize cellulose fibers to DAC. Surprisingly, the oxidation degree became much higher, 43 %, despite that the same condition was employed as before, but the reason for this can be the lower pH that was utilized. Even though there still are questions to be answered, this study has contributed to knowledge that could be utilized to take the oxidation process closer to industrialization.

  • 328.
    Höglund, Hans-Olof
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Helldén, Gustav
    Thomasson, M.
    Wahlberg, Sara
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Development of student teachers' understanding of conditions for life, cycles of matter and energy flow in an aquatic ecosystem - a case study2007Conference paper (Refereed)
  • 329.
    Höglund, Hans-Olof
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Helldén, Gustav
    Thomasson, M.
    Wahlberg, Sara
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Development of student teachers' understanding of conditions for life, cycles of matter and energy flow in an aquatic ecosystem - a case study2008Conference paper (Refereed)
  • 330.
    Höglund, Hans-Olof
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Helldén, Gustav
    Thomasson, Maria
    Wahlberg, Sara
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Student teacher content knowledge of life in an aquatic ecosystem and their experience in a teaching situation- a case study2008Conference paper (Refereed)
  • 331.
    Ismailov, Taner
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Quantification of resin acids, fatty acids and sterols in process and waste water from forest industry2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This work focuses on wood extractives in effluents from the CTMP plant at Skoghall Mill. Pulp and paper industry effluents contain mostly natural compounds which are part of the trees. They are toxic to aquatic life but harmless in nature, as they are present in low concentrations. Processing tons of wood, such as in a pulp mill, strongly increases the concentrations of the toxic compounds (Ali, M. and Sreekrishnan, T., 2001) which have to be treated before transferring to the aquatic environment.Extractives can be found in different forms, as micelles soluble in water, unprocessed in fibers or absorbed on the surface of fibers. It is important to know in which forms extractives are mostly present in the effluent, so that they can be treated more efficiently. It is desired to have extractives absorbed on the fibers and fibrils present in the waste water, so they can be separated from the water and treated separately, e.g. burned for energy recovery. Dissolved extractives complicate the oxygen transfer in an aerated biological treatment step with their surface active properties (Sandberg, 2012).The aim of this study is quantification of extractives on the fibers suspended in the waste water and extractives dissolved in the water. The distribution between the two forms is an important input when designing future effluent treatment. Wood extractives itself are a wide group with different compounds. This work focuses on the main groups present in waste water: resin acids, free and esterified fatty acids and, free and esterified sterols. These groups are analyzed in different process waters and waste water before the waste water treatment plant. The measured concentrations of extractives were as expected, higher in process and effluent waters, lower in white water. Most of the extract was dissolved in the water and unfortunately fiber samples contained very low concentration from the total extract in the samples.

  • 332.
    Jaczewska, Justyna
    et al.
    Institute of Physics, Jagiellonian University, Krakow, Poland.
    Budkowski, Andrzej
    M. Smoluchowski Insitute of Physics, Jagiellonian University, Reymonta 4, Krakow 30–059, Poland.
    Bernasik, Andrzej
    Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, Krakow 30–059, Poland.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Rysz, Jakub
    M. Smoluchowski Insitute of Physics, Jagiellonian University, Reymonta 4, Krakow 30–059, Poland.
    Polymer vs Solvent Diagram of Film Structures Formed in Spin-Cast Poly(3-alkylthiophene) Blends2008In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 41, p. 4802-4810Article in journal (Refereed)
    Abstract [en]

    A polymer vs solvent diagram of film structures, formed in polystyrene (PS) blends (1:1 w:w PS/PT) with poly(3-alkylthiophenes) PT [regioregular R-P3DDT, R-P3HT and regiorandom P3BT, P3DDT] spincoated onto oxidized silicon surfaces from various common solvents [p-xylene, toluene, chloroform, chlorobenzene, cyclohexanone] is presented. The structures were determined with microscopic techniques (atomic, AFM and lateral, LFM, force microscopy, fluorescent microscopy FM) and dynamic secondary ion mass spectrometry (dSIMS). The diagram, arranged according to the solubility parameter of the PTs and the solvents, exhibits three main structural classes: dewetting, lamellar, and lateral (quasi-2-dim) morphology. Decrease in PT solubility parameter δPT inhibits dewetting of polymer films. It induces also a transition from lamellar to lateral film structure. Increase in solvent solubility parameter δS has similar effects. Such behavior is related to the stability of transient homogeneous films and multilayers in the course of spin-casting. The role of δPT and δS is elucidated based on the stability analysis performed in terms of spreading coefficient (dependent on δPT) and effective interfacial tension of solvent-rich polymer phase (dependent on δS).

  • 333.
    Jalan, Ishita
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Lundin, Lisa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    van Stam, Jan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Using solubility parameters to model more environmentally friendly solvent blends for organic solar cell active layers2019In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 23, p. 1-13, article id 3889Article in journal (Refereed)
    Abstract [en]

    To facilitate industrial applications, as well as for environmental and health purposes, there is a need to find less hazardous solvents for processing the photoactive layer of organic solar cells. As there are vast amounts of possibilities to combine organic solvents and solutes, it is of high importance to find paths to discriminate among the solution chemistry possibilities on a theoretical basis. Using Hansen solubility parameters (HSP) offers such a path. We report on some examples of solvent blends that have been found by modelling HSP for an electron donor polymer (TQ1) and an electron acceptor polymer (N2200) to match solvent blends of less hazardous solvents than those commonly used. After the theoretical screening procedure, solubility tests were performed to determine the HSP parameters relevant for the TQ1:N2200 pair in the calculated solvent blends. Finally, thin solid films were prepared by spin-coating from the solvent blends that turned out to be good solvents to the donor-acceptor pair. Our results show that the blend film morphology prepared in this way is similar to those obtained from chloroform solutions.

  • 334. Jandera, P.
    et al.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Lundanes, E.
    Controlling the retention in capillary LC with solvents, temperature and electric fields2004In: J. Sep. Sci. 27 (2004) 1402-1418Article in journal (Refereed)
  • 335.
    Jansson Rådberg, Weronica
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    A model system for understanding the distribution of fines in a paper structure using fluorescence microscopy2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fines have a very important role in paper chemistry and are a determinant in retention,

    drainage and the properties of paper. The purpose of this project was to be able to label the

    fines with fluorophores and study their Brownian motion with fluorescence microscopy.

    When succeeded this could then be used to study fines, fibers and other additives in a

    suspension thus giving the fundamental knowledge of why fines have this important role. Due

    to aggregation of the fines no Brownian motion could be detected. Instead the fines were

    handled as a network system and small fluorescence labeled latex particles were then studied

    in this system. This approach yields information about the fines when the obstacle with

    sedimentation of the network is resolved.

  • 336.
    Jelvez, Alina
    Karlstad University, Faculty of Technology and Science.
    Förskolepedagogers uppfattningar av sitt arbete kring energiomsättningen2010Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this study is to examine the understanding, preschool teachers, have about their work related to energy conversion in the human body. Through individual interviews, answers have been sought to the following questions: What do the preschool teachers believe they need to know about the link between food and energy? What are the different methods preschool teachers use to workwith the area of energy conversion in the human body?

    The results show that preschool teachers have knowledge in terms of food and its nutrients as an energy source for the body to cope with. However the more thorough and detailed questions become all the more uncertainty there is about the topic. Preschool teachers on their own initiative do bring up the topic with the children and begin conversations as well as ask questions, perform experiments and demonstrations. However, there is still a demand for further education in this topic among preschool teachers, as well as requests on advice and ideas on how to work with children around the body’s energy.

    It is important that preschool teachers raise the subject with the children at an early age, in order to create awareness, understanding and interest in the children’s mind. With the children becoming older, also their understanding develops. This drives the importance of the preschool teachers’ performance and commitment in order to obtain meaningful work.

    Keywords: knowledge, work methods, interest, further education.

  • 337.
    Johan, Zetterberg
    Karlstad University, Faculty of Technology and Science.
    NTA som verktyg för naturvetenskap i förskolan: En intervjustudie om NTA:s roll i arbetet med naturvetenskap på förskolan2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to contribute knowledge about the pre-school teachers' view of the role NTA plays in the field of science education. NTA, which stands for Natural Science and Technology for All, is a concept for school development offered for preschool and elementary school. The study uses semi structured interviews. Six preschool teachers at a preschool from four different departments have been interviewed. All preschool teachers have completed NTA training to work with natural science themed boxes. The result shows that NTA is used both planned and spontaneously. Most often, the chil- dren work with the experiments in the boxes in smaller groups, but on some occasions the thematic experiments are used as a demonstration for larger groups. As to how NTA influenced the other teaching, the study shows that it helped to visualize the natural science work and increase the scientific aware- ness of the educators. One conclusion of the survey is that the work on the thematic boxes is an inspiration for the natural science work in the preschool and that the educators are positively prepared for this work.

  • 338.
    Johansson, Emelie
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    β-galaktosidas assay för studie av promotorregion i kloritdismutas från Ideonella dechloratans2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Oxochlorates are anions with a partially naturally occurrence in nature but are also spread by human activities, including the paper industry. These compounds are harmful to both nature and humans, which makes it necessary to find a good way for their degradation. There are two different kinds of bacteria that can use oxochlorates as electron acceptors in their metabolism, bacteria that break down perchlorate and bacteria that break down both perchlorate and chlorate. A bacterium that can break down chlorate under anaerobic conditions is Ideonella dechloratans which holds the genes for chlorite dismutase and chlorate reductase which are enzymes for the degradation of chlorate. Gene expression and enzyme activity of chlorite dismutase are induced under anaerobic conditions, which makes it interesting to find out how this regulation functions in order to better exploit these bacteria in biological wastewater treatment. To study the expression of the gene for chlorite dismutase a potential promoter and regulatory sequence has previously been cloned in a reporter vector and transformed into Escherichia coli (E.coli) bacterium XL-1 blue. This work was to develop a β-galactosidase assay for the quantification of gene expression in this system and apply it to aerobic and anaerobic bacterial cultures. The method was optimized for cultivation in LB-medium and measurements of gene expression showed higher promoter activity during anaerobic compared with aerobic culture conditions for all of the studied clones. This means that all the clones contain a sequence which can function as promoter in E. coli, and that its activity increases during anaerobic conditions.

  • 339.
    Johansson, Jens
    Karlstad University.
    Rening av ett cytokrom c'-liknande protein från Ideonella dechloratans och studier av dess ligandbindningsegenskaper2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 340. Johansson, Kristin
    et al.
    Christophliemk, Hanna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Jönsson, Leif
    Järnström, Lars
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science.
    Effect of Pigment Volume Concentration and Drying Aspects on the Enzyme Activity of Clay Coatings2010Conference paper (Other academic)
  • 341.
    Johansson, Kristin
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Gillgren, Thomas
    Umea Univ, Dept Chem, SE-90187 Umea, Sweden..
    Winestrand, Sandra
    Umea Univ, Dept Chem, SE-90187 Umea, Sweden..
    Järnström, Lars
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science.
    Jonsson, Leif J.
    Umea Univ, Dept Chem, SE-90187 Umea, Sweden..
    Comparison of lignin derivatives as substrates for laccase-catalyzed scavenging of oxygen in coatings and films2014In: Journal of Biological Engineering, ISSN 1754-1611, E-ISSN 1754-1611, Vol. 8, article id 1Article in journal (Refereed)
    Abstract [en]

    Background: Lignin derivatives are phenylpropanoid biopolymers derived from pulping and biorefinery processes. The possibility to utilize lignin derivatives from different types of processes in advanced enzyme-catalyzed oxygen-scavenging systems intended for active packaging was explored. Laccase-catalyzed oxidation of alkali lignin (LA), hydrolytic lignin (LH), organosolv lignin (LO), and lignosulfonates (LS) was compared using oxygen-scavenging coatings and films in liquid and gas phase systems. Results: When coatings containing lignin derivatives and laccase were immersed in a buffered aqueous solution, the oxygen-scavenging capability increased in the order LO < LH < LA < LS. Experiments with coatings containing laccase and LO, LH or LA incubated in oxygen-containing gas in air-tight chambers and at a relative humidity (RH) of 100% showed that paperboard coated with LO and laccase reduced the oxygen content from 1.0% to 0.4% during a four-day period, which was far better than the results obtained with LA or LH. LO-containing coatings incubated at 92% RH also displayed activity, with a decrease in oxygen from 1.0% to 0.7% during a four-day period. The oxygen scavenging was not related to the content of free phenolic hydroxyl groups, which increased in the order LO < LS < LH < LA. LO and LS were selected for further studies and films containing starch, clay, glycerol, laccase and LO or LS were characterized using gel permeation chromatograpy, dynamic mechanical analysis, and wet stability. Conclusions: The investigation shows that different lignin derivatives exhibit widely different properties as a part of active coatings and films. Results indicate that LS and LO were most suitable for the application studied and differences between them were attributed to a higher degree of laccase-catalyzed cross-linking of LS than of LO. Inclusion in active-packaging systems offers a new way to utilize some types of lignin derivatives from biorefining processes.

  • 342.
    Johansson, Kristin
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Gillgren, Thomas
    Umeå Universitet.
    Winestrand, Sandra
    Umeå Universitet.
    Järnström, Lars
    Karlstad University, Faculty of Technology and Science, Paper Surface Centre. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Jönsson, Leif J.
    Umeå Universitet.
    Comparison of lignin derivatives as substrates for laccase-catalyzed scavenging of oxygen in coatings and filmsManuscript (preprint) (Other academic)
    Abstract [en]

    Background: Lignin derivatives are phenylpropanoid biopolymers derived from pulping and biorefinery processes. The possibility to utilize lignin derivatives from different types of processes in advanced enzyme-catalyzed oxygen-scavenging systems intended for active packaging was explored. Laccase-catalyzed oxidation of alkali lignin (LA), hydrolytic lignin (LH), organosolv lignin (LO), and lignosulfonates (LS) was compared using oxygen-scavenging coatings and films in liquid and gas phase systems.

    Results: When coatings containing lignin derivatives and laccase were immersed in a buffered aqueous solution, the oxygen-scavenging capability increased in the order LO < LH < LA < LS. Experiments with coatings containing laccase and LO, LH or LA incubated in oxygen-containing gas in air-tight chambers and at a relative humidity (RH) of 100% showed that paperboard coated with LO and laccase reduced the oxygen content from 1.0% to 0.4% during a four-day period, which was far better than the results obtained with LA or LH. LO-containing coatings incubated at 92% RH also displayed activity, with a decrease in oxygen from 1.0% to 0.7% during a four-day period. The oxygen scavenging was not related to the content of free phenolic hydroxyl groups, which increased in the order LO < LS < LH < LA. LO and LS were selected for further studies and films containing starch, clay, glycerol, laccase and LO or LS were characterized using gel permeation chromatograpy, dynamic mechanical analysis, and wet stability.

    Conclusions: The investigation shows that different lignin derivatives exhibit widely different properties as a part of active coatings and films. Results indicate that LS and LO were most suitable for the application studied and differences between them were attributed to a higher degree of laccase-catalyzed cross-linking of LS than of LO. Inclusion in active-packaging systems offers a new way to utilize some types of lignin derivatives from biorefining processes.

  • 343.
    Johansson, Kristin
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Järnström, Lars
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Winestrand, Sandra
    Kemiska institutionen, Department of Chemistry, Umeå Universitet.
    Chatterjee, Robin
    Kemiska institutionen, Department of Chemistry, Umeå Universitet.
    Jönsson, Leif J.
    Kemiska institutionen, Department of Chemistry, Umeå Universitet.
    Laccases as oxygen scavengers in active-packaging applications2011Conference paper (Other (popular science, discussion, etc.))
  • 344.
    Johansson, Kristin
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Paper Surface Centre.
    Jönsson, Leif J.
    Department of Chemistry, Umeå University.
    Järnström, Lars
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Paper Surface Centre.
    Oxygen scavenging enzymes in coatings: Effect of coating procedures on enzyme activity2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, no 2, p. 197-204Article in journal (Refereed)
    Abstract [en]

    The oxygen content in food packaging may be reduced by attaching oxygen scavengers to the packaging material. The critical parameters that determine the oxygen-scavenging ability of an enzyme-based coating i.e. pH, heat and coating color formulation were evaluated. Glucose oxidase, catalase and glucose were added to latex dispersions in the preparation of the coating colors. The enzymes were entrapped in the coating layers after coating and drying. The clay concentration and drying conditions were varied and the enzymatic activity of the coated layer was evaluated. The need for a pH-buffered system was also studied and the results indicated that, when using a carboxylated latex of a standard coating grade, a buffered system was not needed. A rapid drying at a high temperature was preferred over a slow drying at a low temperature in order to prevent pre-oxidation of the substrate in the wet coating color. The scavenging capacity of the coating was dependent on the amount of substrate for the enzyme reaction left after complete drying. The concentration of clay in the coating formulation was shown to have a marked impact on the oxygen-scavenging ability of the coated layer. The enzyme activity was increased by the addition of clay up to a pigment volume concentration (PVC) of ca. 10%. At higher concentrations of clay, the enzyme activity decreased until the critical pigment volume concentration (CPVC) was reached, probably due to the prevention of diffusion of oxygen and consumption of glucose in the coating process before the layer was completely dried. Further additions of clay above the CPVC resulted in an increased enzyme activity, probably due to the creation of a porous structure.

  • 345.
    Johansson, Kristin
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Paper Surface Centre.
    Winestrand, Sandra
    Kemiska institutionen, Department of Chemistry, Umeå Universitet.
    Johansson, Caisa
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Paper Surface Centre.
    Järnström, Lars
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Paper Surface Centre.
    Jönsson, Leif J.
    Kemiska institutionen, Department of Chemistry, Umeå Universitet.
    Oxygen-scavenging coatings and films based on lignosulfonates and laccase2012In: Journal of Biotechnology, ISSN 0168-1656, Vol. 161, no 1, p. 14-18Article in journal (Refereed)
    Abstract [en]

    Laccase and lignosulfonates were included in coating colors and embedded in latex-based or starch-based films and coatings on foil or board. After 6 days at 23C and 100% relative humidity, the oxygen content in airtight chambers decreased from 1.0% (synthetic gas consisting of 99% N2 and 1% O2) to 0.3% in the presence of board coated with lignosulfonate and laccase, while the oxygen content remained unchanged in control experiments without enzyme. The water stability of lignosulfonate-containing latex-based coatings and starch-based films was improved after laccase-catalyzed oxidation of lignosulfonates, which indicates polymerization to products with lower solubility in water. Furthermore, the E' modulus of starch-based films increased with 30%, which indicates laccase-catalyzed polymerization of lignosulfonates resulting in increased stiffness of the film. The results suggest that laccases and lignosulfonates can be used as an oxygen-scavenging system in active packaging and that enzyme-catalyzed polymerization of lignosulfonates contributes to improved water stability and mechanical properties. 2012 Elsevier B.V.

  • 346.
    Johansson, Kristin
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Paper Surface Centre.
    Winestrand, Sandra
    Kemiska institutionen, Department of Chemistry, Umeå Universitet.
    Järnström, Lars
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Paper Surface Centre.
    Jönsson, Leif J.
    Kemiska institutionen, Department of Chemistry, Umeå Universitet.
    Immobilization of Oxalate Oxidase for Active PackagingManuscript (preprint) (Other academic)
  • 347.
    Johansson, Patricia
    Karlstad University, Faculty of Technology and Science.
    Pedagogers syn på konsumtionen av socker och barns påverkan av pedagogers medhavda mat i förskolan2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There have been many debates in the Swedish media about our sugar consumption, and research shows that children today are eating more candy, soda, snacks and less fruit and vegetables. 

    The purpose of this paper is to examine some pedagogues’ views on diet and its sugar content, in particular, and the pedagogical meals in general, at a pre-school. What is pedagogues’ view of how a good role model should be at the pedagogical meals?

    I did qualitative interviews with six pedagogues. The pedagogues believed that the diet has changed a lot over the years and sugar consumption has decreased in pre-school during the years when they been working. The pedagogues can not affect the diet but can choose to remove some food at the department that they believe is not wholesome. The majority of pedagogues considered it important to be a good role model. During the pedagogical meals it is important to be a good role model; which becomes an educational learning opportunity.

  • 348.
    Johnson, Johanna
    et al.
    Karlstad University, Faculty of Technology and Science.
    Rättö, Peter
    Karlstad University, Faculty of Technology and Science.
    Järnström, Lars
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Lestelius, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Blohm, Erik
    Swedish Pulp and Paper Research Institute (STFI) AB, Stockholm.
    Interaction Between Water And Paperboard And Liner In A Flexographic Printing Press2005In: Taga Journal, ISSN 1748-0337, Vol. 1, no 2, p. 110-128Article in journal (Refereed)
  • 349.
    Johnson, Johanna
    et al.
    Karlstad University, Faculty of Technology and Science.
    Rättö, Peter
    Karlstad University, Faculty of Technology and Science.
    Lestelius, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences, Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science.
    Järnström, Lars
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Paper Surface Centre.
    Dynamic Nip Pressure in a Flexographic CI-Printing Press2003In: TAGA Proceedings, 2003, p. 357-374Conference paper (Other academic)
  • 350.
    Jonhed, Anna
    et al.
    Karlstad University, Faculty of Technology and Science.
    Järnström, Lars
    Karlstad University, Faculty of Technology and Science.
    Phase and gelation behavior of 2-hydroxy-3-(N,N-dimethyl-Ndodecylammonium) propyloxy starches2003In: Starch, ISSN 0038-9056, Vol. 55, no 12, p. 569-575Article in journal (Refereed)
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