Ändra sökning
Avgränsa sökresultatet
45678910 301 - 350 av 2733
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 301.
    Bergenstråhle, Malin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Mazeau, Karim
    CNRS, Ctr Rech Macromol Vegetales.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Molecular modeling of interfaces between cellulose crystals and surrounding molecules: Effects of caprolactone surface grafting2008Ingår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 44, nr 11, s. 3662-3669Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A technical problem in cellulosic nanocomposite materials is the weak interaction between hydrophilic cellulose and hydrophobic polymer matrices. One approach to solve this difficulty is to chemically graft monomers of the matrix polymer onto the cellulose surface. An important question is to understand the effect such surface modification has on the interfacial properties. Semi-empirical approaches to estimate work of adhesion based on surface energies do not provide information on specific molecular interactions. Details about these interactions were obtained using molecular dynamics (MD) simulation. Cellulose interfaces with water and caprolactone medium were modeled with different amounts of grafted caprolactone. The modification lead to an increased work of adhesion between the surface and its surrounding medium. Furthermore, the MD simulations showed that the interaction between cellulose, both modified and non-modified, and surrounding medium is dominated by Coulomb interactions, predominantly as hydrogen bonds.

  • 302.
    Bergenstråhle, Malin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Thormann, Esben
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Nordgren, Niklas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Force Pulling of Single Cellulose Chains at the Crystalline Cellulose-Liquid Interface: A Molecular Dynamics Study2009Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 25, nr 8, s. 4635-4642Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pulling single cellulose molecules from a crystalline cellulose surface has been modeled by molecular dynamics (MD) simulations of the experimental procedure used in atomic force microscopy (AFM). Specifically, the aim of the study was to investigate cellulose interactions at desorption. Simulations were performed in both water and the organic solvent cyclohexane. Moreover, the effects of initial octamer conformation and orientation with respect to the surface chains were studied. A strong effect from the solvent was observed. In cyclohexane, normal forces of 200-500 pN and energies of 43.5 +/- 6.0 kJ/mol glucose unit were required to pull off the octamer. The normal forces in water were substantially lower, around 58 pN, and the energies were 18.2 +/- 3.6 kJ/mol glucose unit. In addition, the lateral components of the pull-off force were shown to provide information on initial conformation and orientation. Hydrogen bonds between the octamer and surface were analyzed and found to be an important factor in the pull-off behavior. Altogether, it was shown that MD provides detailed information on the desorption processes that may be useful for the interpretation of AFM experiments.

  • 303.
    Bergenstråhle, Malin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Wohlert, Jakob
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Larsson, Per Tomas
    STFI-PACKFORSK AB.
    Mazeau, Karim
    CERMAV-CNRS.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Dynamics of Cellulose-Water Interfaces: NMR Spin-Lattice Relaxation Times Calculated from Atomistic Computer Simulations2008Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 112, nr 9, s. 2590-2595Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Solid-state nuclear magnetic resonance (CP/MAS 13C NMR) spectroscopy has often been used to study cellulose structure, but some features of the cellulose NMR spectrum are not yet fully understood. One such feature is a doublet around 84 ppm, a signal that has been proposed to originate from C4 atoms at cellulose fibril surfaces. The two peaks yield different T1, differing by approximately a factor of 2 at 75 MHz. In this study, we calculate T1 from C4-H4 vector dynamics obtained from molecular dynamics computer simulations of cellulose Iβ-water interfacial systems. Calculated and experimentally obtained T1 values for C4 atoms in surface chains fell within the same order of magnitude, 3-20 s. This means that the applied force field reproduces relevant surface dynamics for the cellulose-water interface sufficiently well. Furthermore, a difference in T1 of about a factor of 2 in the range of Larmor frequencies 25-150 MHz was found for C4 atoms in chains located on top of two different crystallographic planes, namely, (110) and (10). A previously proposed explanation that the C4 peak doublet could derive from surfaces parallel to different crystallographic planes is herewith strengthened by computationally obtained evidence. Another suggested basis for this difference is that the doublet originates from C4 atoms located in surface anhydro-glucose units with hydroxymethyl groups pointing either inward or outward. This was also tested within this study but was found to yield no difference in calculated T1.

  • 304.
    Bergenstråhle-Wohlert, Malin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Brady, John W.
    Larsson, Per Tomas
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Westlund, Per-Olof
    Wohlert, Jakob
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Concentration enrichment of urea at cellulose surfaces: results from molecular dynamics simulations and NMR spectroscopy2012Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19, nr 1, s. 1-12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A combined solid-state NMR and Molecular Dynamics simulation study of cellulose in urea aqueous solution and in pure water was conducted. It was found that the local concentration of urea is significantly enhanced at the cellulose/solution interface. There, urea molecules interact directly with the cellulose through both hydrogen bonds and favorable dispersion interactions, which seem to be the driving force behind the aggregation. The CP/MAS (13)C spectra was affected by the presence of urea at high concentrations, most notably the signal at 83.4 ppm, which has previously been assigned to C4 atoms in cellulose chains located at surfaces parallel to the (110) crystallographic plane of the cellulose I beta crystal. Also dynamic properties of the cellulose surfaces, probed by spin-lattice relaxation time (13)CT (1) measurements of C4 atoms, are affected by the addition of urea. Molecular Dynamics simulations reproduce the trends of the T (1) measurements and lends new support to the assignment of signals from individual surfaces. That urea in solution is interacting directly with cellulose may have implications on our understanding of the mechanisms behind cellulose dissolution in alkali/urea aqueous solutions.

  • 305.
    Bergenudd, Helena
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Coullerez, Geraldine
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Malmström, Eva E.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Solvent Effects on ATRP of Oligo(ethylene glycol) Methacrylate. Exploring the Limits of Control2009Ingår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 42, nr 9, s. 3302-3308Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Five copper complexes in combination with six monomer-solvent mixtures have been used to investigate the solvent effects oil ATRP of oligo(ethylene glycol) methacrylate (OEGMA). The redox properties of the copper complexes in OEGMA-solvent mixtures and the apparent rate constants (k(p)(app)) for ATRP of OEGMA were correlated to the degree of control over the polymerizations. Based on this correlation, a general discussion of the limits of control in ATRIP is carried out. One of the key parameters for control in ATRP is the propagation rate constant, making the choice of monomer essential for the design of ail ATRP system. Also, the solvent effects oil the ATRP equilibrium constant (K-ATRP) affect the limit of control (i.e., the apparent rate constant above which control is lost). The choice of copper complex is also more important than the choice of solvent for the design of a well-controlled ATRP system.

  • 306.
    Bergenudd, Helena
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi (stängd 20110630).
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi (stängd 20110630).
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Investigation of iron complexes in ATRP: Indications of different iron species in normal and reverse ATRP2011Ingår i: Journal of Molecular Catalysis A: Chemical, ISSN 1381-1169, E-ISSN 1873-314X, Vol. 346, nr 1-2, s. 20-28Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In an attempt to correlate the ATRP kinetics and the redox properties of the mediator, eight iron complexes with nitrogen, phosphorous and carboxylic acid containing ligands were investigated by electrochemical measurements and by using them as mediators in normal and reverse ATRP of MMA in DMF. The redox properties of the iron complexes in DMF, measured by cyclic voltammetry, did not differ significantly, which was reflected in the ATRP kinetics as the apparent rate constants were practically the same with all the complexing ligands. The degree of control over the polymerization was, however, much improved in reverse ATRP as compared to normal ATRP. In this ATRP system, the ligand type is not crucial for the redox or polymerization properties. Several observations indicate that the iron species in the two systems were not the same, the Fe(III) species resulting from oxidation of Fe(II) in normal ATRP is different from the starting Fe(III) species in reverse ATRP.

  • 307.
    Bergenudd, Helena
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Predicting the Limit of Control in the ATRP Process: Results from Kinetic Simulations2011Ingår i: Macromolecular Theory and Simulations, ISSN 1022-1344, E-ISSN 1521-3919, Vol. 20, nr 9, s. 814-825Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Kinetic simulations are reported, where the ATRP equilibrium constant K(ATRP) is varied and the rates and degree of control in different ATRP systems are evaluated. The apparent rate constant k(app) increases with increasing K(ATRP), but a maximum is reached. The limit of control is passed before the maximum, i.e. when K(ATRP) is increased further, apparent first-order kinetics and well-controlled molecular weights will no longer be obtained. The equilibrium constant at which the limit of control is reached varies linearly with the propagation rate constant. This enables the design of well controlled ATRP systems. The influence of the conversion and chain length dependence of the termination rate constant on the simulation results is discussed.

  • 308.
    Bergenudd, Helena
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Nyström, Daniel
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Heterogeneous iron(II)-chloride mediated radical polymerization of styrene2009Ingår i: Journal of Molecular Catalysis A: Chemical, ISSN 1381-1169, E-ISSN 1873-314X, Vol. 306, nr 1-2, s. 69-76Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In an attempt to perform atom transfer radical polymerization (ATRP) with a more environmentally friendly mediator, polymerization of styrene in the presence of iron(II)-chloride and EDTA was explored from a mechanistic point of view. The presence of EDTA, which normally can form a complex with FeCl2, had no influence on the polymerization results as both the mediator and EDTA were insoluble in the polymerization medium. A mechanism is suggested for the heterogeneous polymerization of styrene mediated by iron (II)-chloride in p-xylene at 50 °C. Varying the mediator amount more than 10-fold revealed that the rate limiting step at low mediator amounts was the adsorption of the initiator or dormant polymer to the mediator surface, whereas at higher mediator amounts, the rate limiting step was instead the activation step in the ATRP equilibrium. The mechanism changed to free radical polymerization in solution at a certain conversion, resulting in lower apparent rate constant and an increased amount of transfer and termination reactions. Chain extension with MMA showed that a significant proportion of the polymer chain ends were active also at high conversions.

  • 309.
    Berger, Pierre Haakon
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Evaluation for improvement of stickies at Utzenstorf Papier2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The recycling of paper and paper products is an important step in the long‐term development of our society. By recycling the paper a more closed circulation of the compounds and additives used in the refining steps of the production occurs and the accumulation leads to difficulties. One of the difficulties concerns stickies. The primary stickies are directly developed during the pulping of recycled products and the secondary stickies occurs by agglomeration of dissolved and colloidal compounds originating from the recycled paper.

    By taking samples from the whole process, the important steps were identified. Concerning macro stickies, the most important step is the fine screening. With two similar de‐inking lines, having their largest difference in how suitable the fine screening, is the differing levels of macro stickies is obvious. The fine screening is the most important step in reducing the load of stickies reaching the paper machine. Re‐arranging DIP 1 into a part‐cascade operation gave a small improvement compared to the potential of an upgraded fine screening. Several trials were made to test the influence of different parameters. An equal air‐pressure in the secondary flotation cells did not eliminate the differences between two parallel lines. Agglomeration of stickies in order to improve the fine screening macro stickie reduction did not show the desired effect. By‐passing of the coarse screening showed a slight quality improvement with less stickies but at the cost of system reliability.Treating the secondary stickies with a de‐activating protein and attaching them to the fiber web with fixing agents makes it possible to lower the stickie load in the white water system. The detackyfying agent had a positive effect on the holes detected by the camera system monitoring the paper web.Continuous measurements of macro stickies and of the colloidal and secondary stickies in the system improve the evaluation of future reconstructions and trials. 

     

  • 310. Berglin, M.
    et al.
    Elwing, H.
    Malkoch, Michael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Löwenhielm, P.
    Kelly, J.
    Lundgren, A.
    Hybrid nanoparticle arrays for measuring the interaction between cell adhesion ligands and macromolecules using SPR2011Ingår i: European Cells and Materials, ISSN 1473-2262, E-ISSN 1473-2262, Vol. 21, nr SUPPL.1, s. 44-Artikel i tidskrift (Refereegranskat)
  • 311.
    Berglund, Birgitta
    et al.
    Psykologiska Institutionen, Stockholms universitet.
    Höglund, Anders
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Shams Esfandabad, Hassan
    Department of Psychology, Imam Khomeini International University.
    A Bisensory Method for Odor and Irritation Detection of Formaldehyde and Pyridine2012Ingår i: Chemosensory Perception, ISSN 1936-5802, Vol. 5, nr 2, s. 146-157Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A bisensory method was developed for determining the psychometric functions and absolute thresholds for odor and sensory irritation of two odorous irritants. Individual and group thresholds for formaldehyde or pyridine were measured for 31 age-matched subjects (18-35 years old). P (50) absolute thresholds were for formaldehyde odor 110 ppb (range 23-505), for pyridine odor 77 ppb (range 20-613), and for pyridine irritation 620 ppb (range 90-3,656); too few subjects' formaldehyde irritation thresholds were possible to determine (human exposures limited to 1 ppm). In spite of large interindividual differences, all thresholds for irritation were higher than for odor. The average slopes of the 62 psychometric functions for odor and the 32 possible for sensory irritation were highest for formaldehyde odor (83% per log ppb) and equal for pyridine odor and irritation (68% per log ppb). The bisensory method for measuring odor and sensory irritation jointly produced detection functions and absolute thresholds compatible with those earlier published; however, a steeper slope for sensory irritation than odor was expected for pyridine. The bisensory method is intended for measuring odor and sensory irritation to broadband mixtures and dynamic exposures, like indoor air.

  • 312.
    Berglund, Jennie
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Resin Profile in a Bleached Kraft Pulp Process2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Målet med projektet var att utreda hur mängden och sammansättningen av hartser varierade i den blekta björkmassan under tillverkningsprocessen på pappersbruket SCA Packaging Munksund. Att göra en litteraturstudie för att ta reda på vilka metoder som kan användas för att förbättra avhartsningen var en annan del av målet.

    Att pappers- och massatillverkare har problem med hartser är vanligt, speciellt när björkved används som råmaterial. Hartserna kan orsaka beläggningar på utrustningen som i sin tur kan leda till processtop, men även prickar och försämrade mekaniska egenskaper hos pappersprodukten.

    Att tillsätta tallolja till kokaren är en vanlig metod som används för att förbättra hartsreningen, att lagra träet innan koket, och lägga fokus på att förbättra barkningen är andra metoder. Även de olika blek- och tvättstegen som används under tillverkningen av massan kan påverka hartshalten.

    I denna studie analyserades massaprover från åtta olika positioner i processen. En Soxtec-utrustning användes för att extrahera massaproverna. Resultatet visade att den mest effektiva avhartsningen sker under tvätten i det första tvättsteget efter kokaren, DD-filtret. Här tvättades 77 % av hartserna ut, och totalt minskade mängden hartser med 88 % under hela processen. PO-pressen var ett annat tvättsteg som var effektivt ur avhartsningssynpunkt. Här togs 36 % av den kvarvarande mängden hartser bort från massan.

    Extrakten som erhållits från extraktionen analyserades vidare med GC-MS och GC-FID. Dessa metoder användes för att identifiera och kvantifiera extraktivämnena, och bestämma hur sammansättningen varierade under tillverkningsprocessen. Tolv olika ämnen identifierades och den substans som visade sig vara svårast att tvätta bort var björkbark hartset, betulinol. Stort sett så var steroler och triterpenoler svårast att bli av med, medans avhartsingen av hartssyror, fettsyror och fettalkoholer var mer effektiv. Det visade sig även att PO-reaktorerna hade en sönderdelande effekt på substanser såsom squalen och betulaprenoler, dessa består av långa kolkedjor med många dubbelbindningar mellan kolatomerna.

  • 313.
    Berglund, Jennie
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Angles d’Ortoli, Thibault
    Vilaplana, Francisco
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Widmalm, Göran
    Bergenstråhle-Wohlert, Malin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Lawoko, Martin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Lindström, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Wohlert, Jakob
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    A molecular dynamics study of the effect of glycosidic linkage type in the hemicellulose backbone on the molecular chain flexibility2016Ingår i: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313XArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    The macromolecular conformation of the constituent polysaccharides in lignocellulosic biomass influences their supramolecular interactions, and therefore their function in plants and their performance in technical products. The flexibility of glycosidic linkages from the backbone of hemicelluloses was studied by evaluating the conformational freedom of the φ and ψ dihedral angles using molecular dynamic simulations, additionally selected molecules were correlated with experimental data by nuclear magnetic resonance spectroscopy. Three types of β-(1→4) glycosidic linkages involving the monosaccharides (Glcp, Xylp and Manp) present in the backbone of hemicelluloses were defined. Different di- and tetrasaccharides with combinations of such sugar monomers from hemicelluloses were simulated, and free energy maps of the φ – ψ space and hydrogen-bonding patterns were obtained. The glycosidic linkage between Glc-Glc or Glc-Man (C-type) was the stiffest with mainly one probable conformation; the linkage from Man-Man or Man-Glc (M-type) was similar but with an increased probability for an alternative conformation making it more flexible, and the linkage between two Xyl-units (X-type) was the most flexible with two almost equally populated conformations. Glycosidic linkages of the same type showed essentially the same conformational space in both disaccharides and in the central region of tetrasaccharides. Different probabilities of glycosidic linkage conformations in the backbone of hemicelluloses can be directly estimated from the free energy maps, which to a large degree affect the overall macromolecular conformations of these polymers. The information gained contributes to an increased understanding of the function of hemicelluloses both in the cell wall and in technical products.

  • 314.
    Berglund, Jennie
    et al.
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Bergenstråhle, Malin
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Vilaplana, Francisco
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova. KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    d'Ortoli, Thibault Angles
    Stockholm Univ, Dept Organ Chem, Stockholm, Sweden..
    Widmalm, Goran
    Stockholm Univ, Dept Organ Chem, Stockholm, Sweden..
    Lawoko, Martin
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Lindström, Mikael
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Wohlert, Jakob
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    How the flexibility properties of hemicelluloses are affected by the glycosidic bonds between different backbone sugars - A molecular dynamics study2016Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Artikel i tidskrift (Övrigt vetenskapligt)
  • 315.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Mechanical behavior of nanostructured cellulosic materials2016Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Artikel i tidskrift (Övrigt vetenskapligt)
  • 316.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Toughness and Strength of Wood Cellulose-based Nanopaper and Nanocomposites2014Ingår i: HANDBOOK OF GREEN MATERIALS, VOL 2: BIONANOCOMPOSITES: PROCESSING, CHARACTERIZATION AND PROPERTIES, World Scientific, 2014, s. 121-129Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Cellulose nanopaper in the form of nanofiber networks show superior mechanical performance and new functional characteristics compared with the brittle paper and fiberboard materials and thermoplastic biocomposites, which are commercially available. The chapter analyzes the potential to combine toughness and strength in polymer matrix nanocomposites based on cellulose nanofiber networks.

  • 317.
    Berglund, Lars A.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Kochumalayil, Joby J.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Ikkala, O.
    Walther, A.
    Bioinspired clay nanocomposites of very high clay content2012Ingår i: ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials, European Conference on Composite Materials, ECCM , 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    It is difficult to prepare clay nanocomposites of high volume fraction clay. Layer-by-layer methods have been successful, but are difficult to use in large-scale production. In the present study, papermaking techniques are used for fabrication of oriented clay platelet nanocomposites. Materials are characterized by TEM, SEM, XRD and mechanical and barrier properties are measured and fire retardance performance is demonstrated. High strength and stiffness is demonstrated and the potential for bionanocomposites is discussed, in particular with moisture durability in mind.

  • 318.
    Berglund, Lars A.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Peijs, Ton
    Cellulose Biocomposites: From Bulk Moldings to Nanostructured Systems2010Ingår i: MRS bulletin, ISSN 0883-7694, E-ISSN 1938-1425, Vol. 35, nr 3, s. 201-207Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose biocomposites are widely used in industry as a low-cost engineering material with plant fiber reinforcement. However, chemical and microstructural heterogeneity causes low strength, low strain-to-failure, high moisture sensitivity, and odor and discoloration problems. Efforts toward improved performance through fiber orientation control, increased fiber lengths, and biopolymer use are reviewed. Interfacial strength control and moisture sensitivity are remaining challenges. As an attractive alternative reinforcement, high-quality cellulose nanofibers obtained by wood pulp fiber disintegration can be prepared at low cost. These nanofibers have high length/diameter ratios, diameters in the 5-15 nm range, and intrinsically superior physical properties. Wood cellulose nanofibers are interesting as an alternative reinforcement to more expensive nanoparticles, such as carbon nanotubes. Nanopaper and polymer matrix nanocomposites based on cellulose nanofiber networks show high strength, high work-of-fracture, low moisture adsorption, low thermal expansion, high thermal stability, high thermal conductivity, exceptional barrier properties, and high optical transparency. The favorable mechanical performance of bioinspired foams and low-density aerogels is reviewed. Future applications of cellulose biocomposites will be extended from the high-volume/low-cost end toward high-tech applications, where cellulose properties are fully exploited in nanostructured materials.

  • 319.
    Berglund, Lars
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Ansari, Mohd Farhan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Cellulose nanocomposites with ductile mechanical behavior2015Ingår i: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    The limited ductility of plant fiber biocomposites is typically caused by interfacial debonding mechanisms at low strain. This leads to damage development and premature failure. The present paper discusses recent results on cellulose nanocomposites with thermoset and thermoplastic matrices, where substantial ductility is observed. The data are presented and reasons for the observed ductility are discussed. 

  • 320.
    Berglund, Lars
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer.
    Sehaqui, Houssine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer.
    Zhou, Qi
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Cellulose-based materials comprising nanofibrillated cellulose from native cellulose2011Patent (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    The present invention relates to cellulose-based materials comprising nanofibrillated cellulose (NFC) from native cellulose. exhibiting highly superior properties as compared to other cellulose-based materials, a method for preparing such cellulose-based material, and uses thereof are also disclosed.

  • 321.
    Berglund, Lars
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer.
    Zhou, Qi
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Kochumalayil, Joby Jose
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer.
    Oxygen barrier for packaging applications2011Patent (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    The present invention relates to composite material of xyloglucan and clay for use as a coating material. The invention also relates to a method of producing the coating.

  • 322.
    Berglund, Per
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi (stängd 20130101).
    Högfeldt, Anna-Karin
    KTH, Skolan för teknikvetenskaplig kommunikation och lärande (ECE), Lärande.
    Karlsson, Sara
    KTH.
    Klasén, Ida
    KTH, Skolan för teknikvetenskaplig kommunikation och lärande (ECE).
    Sandberg, Teresia
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Utvärdering för utveckling: KTH:s samtliga utbildningar under belysning2011Konferensbidrag (Övrigt vetenskapligt)
  • 323. Bergnor, Elisabeth
    et al.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Johansson, E
    The role of metal ions in TCF-bleaching.1994Ingår i: Proceedings 3rd European Workshop on Lignocellulosics and Pulp, 1994, s. 284-289Konferensbidrag (Refereegranskat)
  • 324.
    Bergström, Elina Mabasa
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Salmen, Lennart
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Joby Kochumalayil, Jose
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Plasticized xyloglucan for improved toughness-Thermal and mechanical behaviour2012Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 87, nr 4, s. 2532-2537Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tamarind seed xyloglucan is an interesting polysaccharide of high molar mass with excellent thermomechanical properties. Several plasticizers were studied in order to facilitate thermal processing and improve toughness (work to fracture) of xyloglucan film materials: sorbitol, urea, glycerol and polyethylene oxide. Films of different compositions were cast and studied by thermogravimetric analysis (TGA), calorimetry (DSC), dynamic mechanical thermal analysis (DMA) and tensile tests. Results are analysed and discussed based on mechanisms and practical considerations. Highly favourable characteristics were found with XG/sorbitol combinations, and the thermomechanical properties motivate further work on this material system, for instance as a matrix in biocomposite materials.

  • 325.
    Bergström, Jonas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Flow Field and Fibre Fractionation Studies in Hydrocyclones2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Hydrocyclones can be used to fractionate fibres according to their papermaking potential. The obtained fractions typically differ in fibre wall thickness and/or degree of fibre treatment. Despite a multitude of potential application scenarios, the process has so far had little commercial success. This is largely explained by the low fractionation efficiency and unfavourable operating characteristics of the process.

    The fractionation efficiency of a hydrocyclone is closely related to its flow field. The influence of pulp concentration on the tangential velocity field was therefore studied, by using a self-cleaning pitometer. It was found that the pulp concentration had a strong influence on the tangential velocity. At a feed pulp concentration above 7.5 g/l, the suspension rotated almost as a solid body. As a consequence, the magnitude of radial acceleration and shear stresses decreased dramatically. It is suggested that this is detrimental to the fractionation efficiency.

    The radial velocity field was measured using an Ultrasonic Velocity Profiler. The measurements showed that the rotational centre of the flow field did not correspond with the geometrical centre of the hydrocyclone. This displacement caused the tangential velocity component of the vortex to contribute substantially to the measurement result of the radial velocity component.

    Based on the findings in respect to the flow field studies, a novel design for a fibre fractionation hydrocyclone was proposed. The flow field inside this hydrocyclone was compared to that in a conventional hydrocyclone. It was found, that high radial acceleration and shear stresses could be maintained in the novel design even at high fibre concentration. The fractionation efficiency of the novel hydrocyclone was characterised in terms of surface roughness difference between fine and coarse fraction. When operated with refined bleached softwood kraft pulp, the novel hydrocyclone could produce fractions with a substantial surface roughness difference without deteriorating the dewatering characteristics of the fine fraction. A low thickening of the reject is proposed to be the explanation for that. When fractionating TMP, the best efficiency occurred at a concentration of 10 g/l.

  • 326.
    Bergström, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Poggendorf, Stefanie
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Vomhoff, Hannes
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Measurement of the radial velocity in a cylindrical through-flow hydrocyclone2006Ingår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405Artikel i tidskrift (Övrigt vetenskapligt)
  • 327.
    Bergström, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Vomhoff, Hannes
    Application of a pitometer to measure the tangential velocity in a cylindrical through-flow hydrocyclone operated with a fiber suspension2005Ingår i: Nordic Pulp and Paper Research Journal, ISSN 0283-2631, Vol. 20, nr 1, s. 30-35Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This investigation evaluates a novel fluid velocity measurement method to measure the tangential velocity in a hydrocyclone. The hydrocyclone was operated with an opaque fiber suspension in order to investigate the influence of fiber presence on the tangential velocity distribution. The tangential velocity was measured with a one-hole pitometer, 0.9 mm in diameter, that was equipped with a micro pressure transducer. The pitometer was kept clean with a continuous purge flow. The probe was tested in a cylindrical through-flow hydrocyclone operated with water and 0.4 g/l and 0.8 g/l (0 %, 0.04 % and 0.08 %) addition of a bleached softwood kraft pulp. The velocity profiles measured in pure water agreed qualitatively with velocity distributions that are found in the literature. The outer section had a free vortex-like distribution and the inner section had a solid body rotation. The addition of small amounts of fibers changed the tangential velocity profile significantly. The radius of solid body rotation increased, the maximum tangential velocity decreased and the transition from solid body rotation to free vortex rotation was smoothened.

  • 328.
    Bergström, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Vomhoff, Hannes
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Evaluation of a novel fibre fractionation hydrocyclone2006Artikel i tidskrift (Övrigt vetenskapligt)
  • 329.
    Bergström, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Vomhoff, Hannes
    Literature review of experimental hydrocyclone flow field studies2007Ingår i: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 53, nr 1, s. 8-20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The complex flow field of hydrocyclones has been experimentally investigated on several occasions. Most studies present similar results for the tangential velocity component. In the inner part of the cyclone, it resembles a solid-body rotation, while it typically has a free-vortex-like behavior in the outer part. When looking at the axial velocity component, the results are more diversified. Most studies show a downward velocity close to the wall and an upward velocity in the center. However, some studies report a heavily varying axial velocity over short radii close to the centerline. The radial velocity component appears to be the most problematic one to measure. Dissimilarities in measurement results between the studies are often greater than similarities. However, later studies agree on an increasing inward radial velocity towards the hydrocyclone center. Despite the obvious relationship, extremely little experimental research work can be found in the literature where changes to the flow field are connected to changes in separation efficiency.

  • 330.
    Bergström, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Vomhoff, Hannes
    Söderberg, Daniel
    Tangential velocity measurements in a conical hydrocyclone operated with a fibre suspension2007Ingår i: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 20, nr 4, s. 407-413Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The tangential velocity flow field in a conical hydrocyclone was measured using a self-cleaning pitometer. The influence of pulp fibre concentration on the tangential velocity profile was of particular interest.

    The measurement, showed that the pulp fibres had a strong influence on the tangential velocity profile. When operating the hydrocyclone with pure water, the velocity profile showed the typical combination of free-vortex-like rotation close to the hydrocyclone wall and solid-body-like rotation in the proximity of the hydrocyclone axis. This profile changed significantly when pulp fibres were added. At a low fibre concentration (1.2 g/l), the fibres smoothened the transition between the free-vortex-like and the solid-body-like region of the velocity profile. The location of the maximum tangential velocity moved to a larger radius. At higher fibre concentration (7.5 and 11 g/l), the free-vortex-like behaviour in the outer area was virtually suppressed. Due to networking, the fibre suspension in the entire hydrocyclone behaved as a solid body.

    The radial acceleration profile and tangential rate-of-strain profile were determined. Based on these profiles, a hypothesis was proposed explaining the well-known observation that fractionation efficiency decreases significantly at higher fibre concentrations.

  • 331.
    Bergström, Roger
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Fibre flow mechanisms2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The flow behaviour, and primarily the floc-floc interaction, of pulp paper suspensions have been studied visually. Analogy models based on these observations have been developed as well as the identification of important parameters of floc break-up in low shear rate flow fields. Floc compressions and the locations of voids (areas of lower fibre concentration) where found to influence the floc splitting mechanism. Based on this investigation an equipment for measuring the load carrying ability of fibre flocs and networks was designed, and the effect of measurement geometry, network structure and fibre suspension concentration was investigated. The load carrying ability with concentration increases rapidly when going from 1% to 2% in initial suspension concentration.

    A model handling the fibre floc behaviour during extension and compression has been developed, and some basic flocculated flow mechanisms are discussed on an analogy basis. A modified Voigt element is use, describing mainly the compressional behaviour and plastic behaviour of loose fibre network structures. Further the pos- sibility of stress chain formation is discussed on a fibre level as well as on a floc level.

    The effect of fibre flow (shear field) occurring in the forming zone of a roll former has been studied in detail. Basic forming mechanisms on floc scale has been investi- gated, and the effect of running parameters like dewatering pressure and jet-to-wire speed difference as well as the fibre type and concentration of the pulp suspension has been evaluated. It is evident that floc elongation increases with shear rate (jet-to-wire speed difference) and lower dewatering rate. The latter is because the fibre floc is subjected to the shear field longer due to slower immobilisation. Shorter fibre tends to create weaker networks, which promotes a higher elongation of the flocs.

  • 332.
    Bergström, Roger
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Björkman, Ulf H.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Basic physics of suspended fibre flow systems: I. System scales and basic thermodynamicsManuskript (Övrigt vetenskapligt)
  • 333.
    Bergström, Roger
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Björkman, Ulf H.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Basic physics of suspended fibre flow systems: II. Analogy modelsManuskript (Övrigt vetenskapligt)
  • 334.
    Bergström, Roger
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Björkman, Ulf H.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Material parameters of suspended wood fibre networks: I. Methods of measurementManuskript (Övrigt vetenskapligt)
  • 335.
    Bergström, Roger
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Björkman, Ulf H.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Material parameters of suspended wood fibre networks: II. MeasurementsManuskript (Övrigt vetenskapligt)
  • 336.
    Bergström, Roger
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Björkman, Ulf H.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Stress chains in fibre suspensions: a formation scenarioManuskript (Övrigt vetenskapligt)
  • 337.
    Bergström, Roger
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Björkman, Ulf H.
    The interaction between fibre flocs in shear flow fieldsManuskript (Övrigt vetenskapligt)
  • 338.
    Bergström, Roger
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Norman, Bo
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Floc behaviour during roll formingManuskript (Övrigt vetenskapligt)
  • 339.
    Bergström, Roger
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Åkesson, Krister
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Norman, Bo
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    A twin-wire model gap former: design and evaluation methods2006Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 21, nr 1, s. 54-58Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A one-sided model twin wire gap former, the KTH-former has been developed. The former consists of headbox with transparent gables, forming unit, including a forming roll with a transparent surface and outer forming wire and a reservoir system for water/fibre suspension handling. To allow the study of blade forming, a blade can be introduced against the outer wire to generate a pressure pulse.

    Two measurement techniques have been utilized to study the flow mechanisms of fibre suspension flow in the forming zone;

    A pressure sensor has been used to study the dewatering pressure along the forming zone.

    A high speed video system was used to visually study the suspension flow.

    The study was made with pulp fibres. Fibre floes were introduced in the center of the headbox at the beginning of the linear nozzle contraction, by an introduction tube with an inner diameter of 10 mm. The acceleration in the nozzle contraction was used to separate the fibre floes in the Suspension making them move individually, thus making the visualisations easier. To avoid the problem of floc break-down at nozzle exit when using a conventional linear nozzle with parrot's beak outlet, two Curved contraction blocs were inserted, giving a more constant acceleration profile, letting the floes keep their integrity in the emerging jet.

    The high speed video system had two main arrangements, for the Study of floc behaviour in the forming zone. A mirror installed on the machine structure visualised a certain area of the forming zone. Alternatively, a mirror fastened to the back plate of the forming roll followed a specific area of the wire (and roll), making it possible to follow the floes through the entire forming zone. It is then possible to detect any relative motion between floes and wire.

  • 340. Bexell, U.
    et al.
    Berger, R.
    Olsson, M.
    Grehk, T. M.
    Sundell, P. E.
    Johansson, Mats K. G.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Bonding of vegetable oils to mercapto silane treated metal surfaces: Surface engineering on the nano scale2006Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, nr 2, s. 838-841Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper the bonding of thin vegetable oil films on mercapto silane treated aluminium surfaces has been studied. The silane molecules are attached to the surface by metal-oxygen-silicon bonds. The coupling between the unsaturated bonds of the vegetable oil and the thiol functionalised surface was obtained through a photoinduced thiol-ene reaction. The surfaces were characterised by X-ray photoelectron spectroscopy (XPS). Vegetable oil contains both saturated and unsaturated carbon chains. For the reactions investigated in this study it is the unsaturated carbon chains that can react by a thiol-ene reaction and the results indicate that it is possible to attach a vegetable oil to a metal surface pre-treated with a thiol functionalised silane.

  • 341.
    Bi, Ran
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Lignocellulose Degradation by Soil Micro-organisms2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Lignocellulosic biomass is a sustainable resource with abundant reserves. Compared to petroleum ‐ based products, the biomass ‐ derived polymers and chemicals give better environmental profiles. A lot of research interest is focused on understanding the lignocellulose structures.

    Lignin, among the three major wood components, represents most difficulty for microbial degradation because of its complex structure and because cross ‐ linking to hemicellulose makes wood such a compact structure. Nevertheless, wood is naturally degraded by wood ‐ degrading micro ‐ organisms and modified and partly degraded residual of lignin goes into soil. Therefore soil serves as a good environment in which to search for special lignin ‐ degraders. In this thesis, different types of lignin have been used as sole carbon sources to screen for lignin ‐ degrading soil micro ‐ organisms. Eleven aerobic and three anaerobic microbe strains have been isolated and identified as able to grow on lignin. The lignin degradation patterns of selected strains have been studied and these partly include an endwise cleavage of  β‐ O ‐ 4 bonds in lignin and is more complex than simple hydrolytic degradation.

    As lignin exists in wood covalently bonded to hemicellulose, one isolated microbe strain, Phoma herbarum, has also been studied with regards to its ability to degrade covalent lignin polysaccharide networks (LCC). The results show that its culture filtrate can attack lignin ‐ polysaccharide networks in a manner different from that of the commercial enzyme product, Gammanase, possibly by selective cleavage of phenyl glucoside bonds. The effects on LCC of Phoma herbarum also enhance polymer extractability. Hot ‐ water extraction of a culture filtrate of Phoma herbarum ‐ treated fiberized spruce wood material gave an amount of extracted galactoglucomannan more than that given by the Gammanase ‐ treated material and non ‐ enzyme ‐ treated material.

    Over millions of years of natural evolution, micro ‐ organisms on the one hand develop so that they can degrade all wood components to get energy for growth, while plants on the other hand also continuously develop to defend from microbial attack. Compared with lignin and cellulose, hemicelluloses as major components of plant cell walls, are much more easily degraded, but hemicelluloses differ from cellulose in that they are acetylated to different extents. The biological functions of acetylation are not completely understood, but it is suggested is that one function is to decrease the microbial degradability of cell walls. By cultivation of soil micro ‐ organisms using mannans acetylated to deffernent degrees as sole carbon source on agar plates, we were able to see significant trends where the resistance towards microbial degradation of glucomannan and galactomannan increased with increasing degree of acetylation. Possible mechanisms and the technological significance of this are discussed. Tailoring the degree of acetylation of polysaccharide materials might slow down the biodegradation, making it possible to design a material with a degradation rate suited to its application.

  • 342.
    Bi, Ran
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Azhar, Shoaib
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Mckee, Lauren
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Culture Filtrates from a Soil Organism Enhances Extractability of Polymers from Fiberised Spruce WoodManuskript (preprint) (Övrigt vetenskapligt)
  • 343.
    Bi, Ran
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Berglund, Jennie
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Vilaplana, Francisco
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    McKee, Lauren
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    The Degree Of Acetylation Affects The Microbial Degradability Of HemicellulosesManuskript (preprint) (Övrigt vetenskapligt)
  • 344.
    Bi, Ran
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Berglund, Jennie
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Vilaplana, Francisco
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    McKee, Lauren S.
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    The degree of acetylation affects the microbial degradability of mannans2016Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 133, s. 36-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hemicelluloses as major components of plant cell walls are acetylated to different extents. The biologicalfunctions of acetylation are not completely understood but suggested that one reason is to decrease themicrobial degradability of cell walls. Model seed galactomannan and glucomannan, which are structurallysimilar to an abundant class of wood hemicelluloses, were acetylated to various degrees and usedas sole carbon source on agar plates for microbial growth. When soil samples were inoculated on theplates, significantly fewer strains grew on the agar plates with highly acetylated mannans than withslightly acetylated or non-acetylated mannans. One filamentous fungus isolated and identified as aPenicillium species was shown to grow faster and stronger on non-acetylated than on highly acetylatedmannan. The data therefore support the hypothesis that a high degree of acetylation (DSac) can decreasethe microbial degradability of hemicelluloses. Possible mechanisms and the technological significance ofthis are discussed.

  • 345.
    Bi, Ran
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Isolation and identification of soil microorganisms under anaerobic condition which is able to live on lignin as carbon source2012Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 243Artikel i tidskrift (Övrigt vetenskapligt)
  • 346.
    Bi, Ran
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Huang, Shan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    ISOLATION OF EXCEEDINGLY LOW OXYGEN CONSUMING FUNGAL STRAINS ABLE TO UTILIZE LIGNIN AS CARBON SOURCE2016Ingår i: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 50, nr 7-8, s. 811-817Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lignin biodegradation is normally related to aerobic microorganisms, and it is often claimed that microbes do not metabolize lignin as a carbon source. In this work, several fungal strains were isolated from the sediment of a small stream located in a forest and tested on agar plates with lignin as the only carbon source. All identified strains were Ascomycetes, Penicillium spinulosum, Pseudeurotium bakeri and Galactomyces geotrichum. When cultivated in shaking flasks with lignosulphonate as a carbon source, the lignin was consumed, and cell free culture filtrates appeared to depolymerize lignosulphonate to some extent. It is suggested that the strains detected are part of a symbiotic community and live in a microbiological niche in which they are able to utilize lignin residues left from brown rot and humus having extremely low oxygen content.

  • 347.
    Bi, Ran
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Huang, Shan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. Linnaus University, Sweden.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Isolation of exceedingly low oxygen consuming fungal strains able to utilize lignin as carbon sourceIngår i: Cellulose Chemistry and Technology, ISSN 0576-9787Artikel i tidskrift (Refereegranskat)
  • 348.
    Bi, Ran
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Lawoko, Martin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Phoma herbarum, a soil fungus able to grow on natural lignin and synthetic lignin (DHP) as sole carbon source and cause lignin degradationManuskript (preprint) (Övrigt vetenskapligt)
  • 349.
    Bi, Ran
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Oinonen, Petri
    Ecohelix AB, Teknikringen 38, 10044 Stockholm, Sweden.
    Wang, Yan
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    A Method for Studying Effects on Lignin-Polysaccharide Networks during Biological Degradation and Technical Processes of Wood2016Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 1, s. 1307-1318Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Woody tissues consist primarily of a mixture of cellulose, hemicelluloses, and lignin. Covalent bonds between lignin and polysaccharides likely play a central role in determining the mechanical and physical properties of wood. Intact and defined lignin-polysaccharide networks have not been isolated in large quantities because of the recalcitrance of lignin, which demands harsh chemical treatments that alter its structure. This report presents a method for preparing large quantities of lignin-polysaccharide networks similar to those naturally present in wood based on the enzymatic oxidation of hemicellulose from Norway spruce. Fungal enzymes produced from various carbon sources were used to depolymerize these networks. The method was used for simulating "enzyme mining" - a concept in biorefineries, giving a possible explanation for its mechanisms.

  • 350.
    Bi, Ran
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Oinonen, Petri
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Wang, Yan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    A method for studying effects on lignin-polysaccharide networks during degradation and technical processing of woodManuskript (preprint) (Övrigt vetenskapligt)
45678910 301 - 350 av 2733
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf