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  • 301.
    Blumer, Hartwig
    et al.
    Luleå tekniska universitet.
    Johansson, Ingvar
    Luleå tekniska universitet.
    Lindberg, Henrik
    Luleå tekniska universitet.
    Träkompositer: forskning, utveckling, tillverkning1993Rapport (Övrigt vetenskapligt)
  • 302.
    Blumer, Hartwig
    et al.
    Luleå tekniska universitet.
    Lindberg, Henrik
    Luleå tekniska universitet.
    Johansson, Ingvar
    Luleå tekniska universitet.
    Träkompositer: kunskapsöversikt och forskningsbehov1992Rapport (Övrigt vetenskapligt)
  • 303. Boldinova, Elizaveta O.
    et al.
    Stojkovic, Gorazd
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Khairullin, Rafil
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Kazan Volga Reg Fed Univ, Russia.
    Wanrooij, Sjoerd
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Makarova, Alena V.
    Optimization of the expression, purification and polymerase activity reaction conditions of recombinant human PrimPol2017Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, nr 9, artikel-id e0184489Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Human PrimPol is a DNA primase/polymerase involved in DNA damage tolerance and prevents nuclear genome instability. PrimPol is also localized to the mitochondria, but its precise function in mitochondrial DNA maintenance has remained elusive. PrimPol works both as a translesion (TLS) polymerase and as the primase that restarts DNA replication after a lesion. However, the observed biochemical activities of PrimPol vary considerably between studies as a result of different reaction conditions used. To reveal the effects of reaction composition on PrimPol DNA polymerase activity, we tested the polymerase activity in the presence of various buffer agents, salt concentrations, pH values and metal cofactors. Additionally, the enzyme stability was analyzed under various conditions. We demonstrate that the reaction buffer with pH 6-6.5, low salt concentrations and 3 mM Mg2+ or 0.3-3 mM Mn2+ cofactor ions supports the highest DNA polymerase activity of human PrimPol in vitro. The DNA polymerase activity of PrimPol was found to be stable after multiple freeze-thaw cycles and prolonged protein incubation on ice. However, rapid heat-inactivation of the enzyme was observed at 37 degrees C. We also for the first time describe the purification of human PrimPol from a human cell line and compare the benefits of this approach to the expression in Escherichia coli and in Saccharomyces cerevisiae cells. Our results show that active PrimPol can be purified from E. coli and human suspension cell line in high quantities and that the activity of the purified enzyme is similar in both expression systems. Conversely, the yield of full-length protein expressed in S. cerevisiae was considerably lower and this system is therefore not recommended for expression of full-length recombinant human PrimPol.

  • 304.
    Bollok, Monika
    et al.
    KTH, Skolan för bioteknologi (BIO).
    Henriksson, Hongbin
    KTH, Skolan för bioteknologi (BIO).
    Kallas, Åsa
    KTH, Skolan för bioteknologi (BIO).
    Jahic, Mehmedalija
    KTH, Skolan för bioteknologi (BIO).
    Teeri, Tuula T.
    KTH, Skolan för bioteknologi (BIO).
    Enfors, Sven-Olof
    KTH, Skolan för bioteknologi (BIO).
    Production of poplar xyloglucan endotransglycosylase using the methylotrophic yeast Pichia pastoris2005Ingår i: Applied Biochemistry and Biotechnology, ISSN 0273-2289, Vol. 126, s. 61-77Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The gene XET16A encoding the enzyme xyloglucan endotransglycosylase (XET) from hybrid aspen (Populus tremula x tremuloides Mich) was transformed into Pichia pastoris GS115 and the enzyme was secreted to the medium. The influence of process conditions on the XET production, activity, and proteolytic degradation were examined. Inactivation of XET occurred in the foam, but could be decreased significantly by using an efficient antifoam. Rich medium (yeast extract plus peptone) was needed for product accumulation, but not for growth. The proteolytic degradation of the enzyme in the medium was substantially decreased by also adding yeast extract and peptone to the glycerol medium before induction with methanol. Decreasing the fermentation pH from 5.0 to 4.0 further reduced the proteolysis. The specific activity was further improved by production at 15 degrees C instead of 22 degrees C. In this way a XET production of 54 mg/L active enzyme could be achieved in the process with a specific activity of 18 Unit/mg protein after a downstream process including centrifugation, micro- and ultrafiltration, and ion exchange chromatography.

  • 305. Bondeson, Daniel
    et al.
    Kvien, Ingvild
    Oksman, Kristiina
    Bio-nanocomposites based on cellulose whiskers2006Ingår i: 6th Global Wood and Natural Fibre Composites Symposium: April 05 - 06, 2006 ; scientific presentations / [ed] Andrzej K. Bledzki, Lehrstuhl Kunststoff- und Recyclingtechnik , 2006Konferensbidrag (Refereegranskat)
  • 306.
    Bondeson, Daniel
    et al.
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Kvien, Ingvild
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Oksman, Kristiina
    Strategies for preparation of cellulose whiskers from microcrystalline cellulose as reinforcement in nanocomposites2006Ingår i: Cellulose Nanocomposites: Processing, characterization and Properties, Washington: American Chemical Society (ACS), 2006, s. 10-25Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 307.
    Bondeson, Daniel
    et al.
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Mathew, Aji P.
    Oksman, Kristiina
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Optimization of the Isolation of Nanocrystals from Microcrystalline Cellulose by Acid Hydrolysis2006Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 13, nr 2, s. 171-180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of this work was to find a rapid, high-yield process to obtain an aqueous stable colloid suspension of cellulose nanocrystals/whiskers. Large quantities are required since these whiskers are designed to be extruded into polymers in the production of nano-biocomposites. Microcrystalline cellulose (MCC), derived from Norway spruce (Picea abies), was used as the starting material. The processing parameters have been optimized by using response surface methodology. The factors that varied during the process were the concentration of MCC and sulfuric acid, the hydrolysis time and temperature, and the ultrasonic treatment time. Responses measured were the median size of the cellulose particles/whiskers and yield. The surface charge as calculated from conductometric titration, microscopic examinations (optical and transmission electron microscopy), and observation of birefringence were also investigated in order to determine the outcome (efficiency) of the process. With a sulfuric acid concentration of 63.5% (w/w), it was possible to obtain cellulose nanocrystals/whiskers with a length between 200 and 400 nm and a width less than 10 nm in approximately 2 h with a yield of 30% (of initial weight).

  • 308.
    Bondeson, Daniel
    et al.
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Dispersion and characteristics of surfactant modified cellulose whiskers nanocomposites2007Ingår i: Composite interfaces (Print), ISSN 0927-6440, E-ISSN 1568-5543, Vol. 14, nr 7-9, s. 617-630Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Biodegradable nanocomposites based on 5 wt% cellulose nanowhiskers (CNW) and polylactic acid (PLA) were prepared using an extrusion process. An anionic surfactant (5, 10, and 20 wt%) was used to improve the dispersion of the CNW in the PLA matrix. The results showed that increased surfactant content resulted in improved dispersion but at the same time degraded the PLA matrix. The results from mechanical testing showed a maximum modulus for the composite with 5 wt% surfactant and as the surfactant content increased, the CNW dispersion improved and the tensile strength and elongation at break was improved compared to its unreinforced counterpart.

  • 309. Bondeson, Daniel
    et al.
    Oksman, Kristiina
    Optimization of the preparation of nano crystals from microcrystalline cellulose in aqueous suspensions2005Ingår i: Abstracts of papers, 229th ACS national meeting : San Diego, CA, March 13 - 17, 2005, Washington, DC: American Chemical Society (ACS), 2005Konferensbidrag (Refereegranskat)
  • 310.
    Bondeson, Daniel
    et al.
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Polylactic acid/cellulose whisker nanocomposites modified by polyvinyl alcohol2007Ingår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 38, nr 12, s. 2486-2492Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study was to produce biodegradable polylactic acid/cellulose whisker nanocomposites by compounding extrusion and investigate the possibility to use polyvinyl alcohol to improve the dispersion of whiskers in the matrix. Two feeding methods of polyvinyl alcohol and cellulose nanowhiskers were used and evaluated, dry-mixing with polylactic acid prior extrusion or pumping as suspension directly into the extruder. Various microscopic techniques, tensile testing, and dynamic mechanical thermal analysis were used to study the structure and properties of the nanocomposites. Due to immiscibility of the polymers, phase separation occurred with a continuous polylactic acid phase and a discontinuous polyvinyl alcohol phase. The whiskers were primarily located in the polyvinyl alcohol phase and only a negligible amount was located in the polylactic acid phase. This inadequate dispersion of whiskers in the polylactic acid phase was probably the reason why no improvements in thermal properties were seen for the nanocomposites. The relative small improvements in tensile modulus, tensile strength, and elongation to break for the nanocomposites also indicated that it was principally the polyvinyl alcohol phase that was reinforced with whiskers but not the polylactic acid phase.

  • 311.
    Bondeson, Daniel
    et al.
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Syre, Peder
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    All cellulose nanocomposites produced by compounding extrusion2007Ingår i: Journal of Biobased Materials and Bioenergy, ISSN 1556-6560, E-ISSN 1556-6579, Vol. 1, nr 3, s. 367-371Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A transparent biobased nanocomposite of 5 wt% cellulose nanowhiskers (CNW) and cellulose acetate butyrate (CAB), plasticized by triethyl citrate (TEC), was produced by melt extrusion. The cellulose nanowhiskers were prepared from commercially available microcrystalline cellulose (MCC) by hydrochloric acid hydrolysis. The plasticizer, TEC, was solved in the whisker suspension and this suspension was pumped into the extruder during the compounding process. Scanning electron microscopy, tensile testing, and dynamic mechanical thermal analysis were used to study the structure and properties of the nanocomposite. The tensile modulus and strength indicated an improvement with 300% and 100%, respectively, compared to neat CAB but the elongation at break was decreased. Further more, the softening temperature of CAB was extended for the nanocomposite. Results from DMTA showed that the tanδ peak temperature was shifted by 31 °C, from 117 °C to 148 °C with addition of CNW in CAB. The extrusion process with liquid feeding was shown to be successful for this material combination. AbstractA transparent biobased nanocomposite of 5 wt% cellulose nanowhiskers (CNW) and cellulose acetate butyrate (CAB), plasticized by triethyl citrate (TEC), was produced by extrusion compounding. The cellulose nanowhiskers were prepared from commercially available microcrystalline cellulose (MCC) by hydrochloric acid hydrolysis. The plasticizer, TEC, was solved in the whisker suspension and this suspension was pumped into the extruder during the compounding process. Scanning electron microscopy, tensile testing, and dynamic mechanical thermal analysis were used to study the structure and properties of the nanocomposite. The tensile modulus and strength were improved with 300% and 100%, respectively, compared to neat CAB but the elongation at break was decreased. Further more, the softening temperature of CAB was extended for the nanocomposite. Results from DMTA showed that the tan d peak temperature was shifted by 31 ˚C, from 117 °C to 148 ˚C with addition of CNW in CAB.

  • 312.
    Bondesson, Laban
    KTH, Skolan för bioteknologi (BIO).
    Microscopic views of drug solubility2006Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The development of computational models for predicting drug solubility has increased drastically during the last decades. Nevertheless these models still have diffculties to estimate the aqueous solubility as accurate as desired. In this thesis di erent aspects that are known to have a large impact on the aqueous solubility of a molecule have been studied in detail using various theoretical methods with intension to provide microscopic view on drug solubility. The rst aspect studied is the hydrogen bond energies. Eight drug molecules have been calculated using density functional theory and the validity of additive model that has often been used in solubility models is examined. The impact of hydrogen bonds in Infrared and Raman spectra of three commonly used drug molecules has also been demonstrated. The calculated spectra are found to be in good agreement with the experimental data. Another aspect that is important in solubility models is the volume that a molecule occupies when it is dissolved in water. The volume term and its impact on the solvation energy has therefore also been calculated using three di erent methods. It was shown that the calculated volume di ered signi cantly dependent on which method that had been used, especially for larger molecules.

    Most of the solubility models assume the solute molecule to be in the bulk of the solvent. The molecular behavior at the water/gas interface has been investigated to see how it di ers from bulk. It was seen that the concentration close to the interface was almost three times higher than in the bulk. The increase in concentration close to the surface depends on the larger gap between the interface energy and the gas phase energy than between the bulk energy and the gas phase energy.

  • 313.
    Bondza, Sina
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Medicinsk strålningsvetenskap. Ridgeview Instruments AB, Vange, Sweden.
    Foy, Eleanor
    Univ Leeds, Leeds Inst Rheumat & Musculoskeletal Med, Leeds, W Yorkshire, England..
    Brooks, Jonathan
    Pfizer Inc, Cambridge, MA USA..
    Andersson, Karl
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Medicinsk strålningsvetenskap. Ridgeview Instruments AB, Vange, Sweden.
    Robinson, James
    Univ Leeds, Leeds Inst Rheumat & Musculoskeletal Med, Leeds, W Yorkshire, England..
    Richalet, Pascale
    BioRevera LLC, Arlington, MA USA..
    Buijs, Jos
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Medicinsk strålningsvetenskap. Ridgeview Instruments AB, Vange, Sweden.
    Real-time Characterization of Antibody Binding to Receptors on Living Immune Cells2017Ingår i: Frontiers in Immunology, ISSN 1664-3224, E-ISSN 1664-3224, Vol. 8, artikel-id 455Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding molecular interactions on immune cells is crucial for drug development to treat cancer and autoimmune diseases. When characterizing molecular interactions, the use of a relevant living model system is important, as processes such as receptor oligomerization and clustering can influence binding patterns. We developed a protocol to enable time-resolved analysis of ligand binding to receptors on living suspension cells. Different suspension cell lines and weakly adhering cells were tethered to Petri dishes with the help of a biomolecular anchor molecule, and antibody binding was analyzed using LigandTracer. The protocol and assay described in this report were used to characterize interactions involving eight cell lines. Experiments were successfully conducted in three different laboratories, demonstrating the robustness of the protocol. For various antibodies, affinities and kinetic rate constants were obtained for binding to CD20 on both Daudi and Ramos B-cells, the T-cell co-receptor CD3 on Jurkat cells, and the Fc gamma receptor CD32 on transfected HEK293 cells, respectively. Analyzing the binding of Rituximab to B-cells resulted in an affinity of 0.7-0.9 nM, which is similar to values reported previously for living B-cells. However, we observed a heterogeneous behavior for Rituximab interacting with B-cells, which to our knowledge has not been described previously. The understanding of complex interactions will be facilitated with the possibility to characterize binding processes in real-time on living immune cells. This provides the chance to broaden the understanding of how binding kinetics relate to biological function.

  • 314.
    Bonturi, Nemailla
    et al.
    Department of Materials and Bioprocess Engineering, School of Chemical Engineering, State University of Campinas.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Nilsson, Robert
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Miranda, Everson Alves
    Department of Materials and Bioprocess Engineering, School of Chemical Engineering, State University of Campinas.
    Berglund, Kris
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Single Cell Oil Producing Yeasts Lipomyces starkeyi and Rhodosporidium toruloides: Selection of Extraction Strategies and Biodiesel Property Prediction2015Ingår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 8, nr 6, s. 5040-5052Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Single cell oils (SCOs) are considered potential raw material for the production of biodiesel. Rhodosporidium sp. and Lipomyces sp. are good candidates for SCO production. Lipid extractability differs according to yeast species and literature on the most suitable method for each oleaginous yeast species is scarce. This work aimed to investigate the efficiency of the most cited strategies for extracting lipids from intact and pretreated cells of Rhodosporidium toruloides and Lipomyces starkeyi. Lipid extractions were conducted using hexane or combinations of chloroform and methanol. The Folch method resulted in the highest lipid yields for both yeasts (42% for R. toruloides and 48% for L. starkeyi). Also, this method eliminates the cell pretreatment step. The Bligh and Dyer method underestimated the lipid content in the tested strains (25% for R. toruloides and 34% for L. starkeyi). Lipid extractability increased after acid pretreatment for the Pedersen, hexane, and Bligh and Dyer methods. For R. toruloides unexpected fatty acid methyl esters (FAME) composition were found for some lipid extraction strategies tested. Therefore, this work provides useful information for analytical and process development aiming at biodiesel production from the SCO of these two yeast species.

  • 315.
    Boons, Frank
    et al.
    University of Manchester, UK.
    Spekkink, Wouter
    Delft University of Technology, The Netherlands.
    Isenmann, Ralf
    Munich University of Applied Sciences, Germany.
    Baas, Leenard
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska fakulteten.
    Eklund, Mats
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska fakulteten.
    Brullot, Sabrina
    Institut Charles Delaunay, France.
    Deutz, Pauline
    University of Hull, UK.
    Gibbs, David
    University of Hull, UK.
    Massard, Guillaume
    Université de Lausanne, Switzerland.
    Romero Arozamena, Elena
    University of Cantabria, Spain.
    Ruiz Puente, Carmen
    University of Cantabria, Spain.
    Verguts, Veerle
    Flemish Land Agency, Belgium.
    Davis, Chris
    Delft University of Technology, The Netherlands.
    Korevaar, Gijsbert
    Delft University of Technology, The Netherlands.
    Costa, Inês
    3Drivers.
    Baumann, Henrikke
    Chalmers tekniska högskola, Sweden.
    Comparing industrial symbiosis in Europe: towards a conceptual framework and research methodology2015Ingår i: International perspectives on industrial ecology / [ed] Pauline Deutz, Donald I Lyons, Jun Bi, Cheltenham: Edward Elgar Publishing, 2015, s. 69-88Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Industrial symbiosis (IS) continues to raise the interest of researchers and practitioners alike. Individual and haphazard attempts to increase linkages among co-located firms have been complemented by concerted efforts to stimulate the development of industrial regions with intensified resource exchanges that reduce environmental impact. Additionally, there are examples of both spontaneous and facilitated linkages between two or more firms involving flows of materials/energy waste. A striking feature of IS activities is that they are found across diverse social contexts and vary considerably in form (Lombardi et al., 2012); there are substantial differences in the ways in which IS manifests itself. Equally diverse are the activities of policy makers to stimulate such linkages. Such diversity can already be found within Europe, as became apparent in a first meeting among some of the present authors in 2009 (Isenmann and Chernykh, 2009). Researchers present there decided to create a network of European researchers on IS, with the explicit aim to develop a comparative analysis. We can thus provide insight to the relationship between the style of IS and its context and thereby the potential for policy makers in different contexts to learn from each other. Policy learning can be a tempting route to IS, but is fraught with difficulties if the influence of context is not appreciated (e.g., Wang et al., Chapter 6, this volume).

  • 316.
    Borenberg, Fredrik
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Biofiltrering av luft förorenad med terpener: Biofiltration of air polluted with terpenes2008Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [sv]

    Utsläpp av lättflyktiga organiska föreningar (VOC) är ett växande mijlöproblem. Biofiltrering är ett relativt billigt sätt att rena luft förorenad med VOC. Biofiltrering har också en fördel i att föroreningen helt bryts ned och inte endast övergår i en annan form. Rapporten beskriver arbetet kring två biofilter av kolonntyp. Mikroberna som användes kom från främst träflis och jord. Som förorening användes limonen och α-pinen. Analys skedde med gaskromatografi.

    Vidare undersöktes om närvaro av silikonolja i filterbädden påverkade resultatet Reningskapaciteten uppgick i filtret utan olja till ca 10 - 12 g/m3.h under de första 25 dagarna i drift och ökade därefter till ca 15 - 20 g/m3.h. Motsvarande data för det oljeberikade filtret är ca 15 - 20 g/m3.h i båda fallen

  • 317.
    Borg, Ann-Louise
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Investigation of a Method for Determination of Anticomplementary Activity (ACA) in Octagam2009Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This Master Thesis was conducted at Octapharma AB in Stockholm.

    Anticomplementary activity (ACA) is a measure of the product’s abilities to activate the complement system. IgG aggregates are mainly responsible for this activation. Two different performances of a method for determination of ACA in Octagam® are available. The two performances are based on the reference method for test of ACA in immunoglobulins in the European Pharmacopoeia Commission Guideline 6.0 (chapter 2.6.17). The method is carried out either in test tubes or on microtiter plates. The test tube method can be performed either in a manual manner or modified, being more automated. The latter performance has been applied in this study. The plate method is more automated than both of the tube methods. The plate method and the manual tube method have earlier seemed to result in different outcomes, which was the basis for this thesis.

    The plate method and the modified test tube method have been compared and robustness parameters have been studied in order to see which factors influence on the end result. The adequacy of using Human Biological Reference Preparation (human BRP) as a control for the ACA method in general has also been investigated. Samples of the product are outside the scope of this thesis and have not been investigated.

    According to this study, the plate method and the modified tube method are not comparable with regard to complement titration results and to ACA of the BRP control. A higher precision is gained with the plate method. This in combination with the higher degree of automation makes the plate method advantageous in several aspects. When it comes to the robustness of the ACA method in general, the sheep red blood cells (SRBC) used are critical. Haemolysin dilution and complement activity seem to be critical as well.

    Human BRP is, according to this study more adequate as a reference for the plate method than for the tube method. An In house control is believed to be more representative to the ACA method in general as it is of the same nature as the samples analysed, in contrast to the human BRP.

  • 318.
    Borges, Ana C.
    et al.
    École Polytechnique Fédérale de Lausanne.
    Eyholzer, Christian
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Duc, Fabien
    École Polytechnique Fédérale de Lausanne.
    Bourban, Pierre-Etienne
    École Polytechnique Fédérale de Lausanne.
    Tingaut, Philippe
    Swiss Federal Laboratories for Materials Testing and Research (EMPA).
    Zimmermann, Tanja
    Swiss Federal Laboratories for Materials Testing and Research (EMPA).
    Pioletti, Dominique P.
    École Polytechnique Fédérale de Lausanne.
    Månson, Jan-Anders E.
    École Polytechnique Fédérale de Lausanne.
    Nanofibrillated cellulose composite hydrogel for the replacement of the Nucleus Pulposus2011Ingår i: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 7, nr 9, s. 3412-3421Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The swelling and compressive mechanical behavior as well as the morphology and biocompatibility of composite hydrogels based on Tween® 20 trimethacrylate (T3), N-vinyl-2-pyrrolidone (NVP) and nanofibrillated cellulose (NFC) were assessed in the present study. The chemical structure of T3 was verified by FTIR and 1H NMR and the degree of substitution (DS) was found to be around 3. Swelling ratios of neat hydrogels composed of different concentrations of T3 and NVP were found to range from 1.5 to 5.7 with decreasing concentration of T3. Various concentrations of cellulose nanofibrils (0.2 to 1.6 wt%) were then used to produce composite hydrogels that showed lower swelling ratios than neat ones for a given T3 concentration. Neat and composite hydrogels exhibited typical non-linear response under compression. All composite hydrogels showed an increase in elastic modulus compared to neat hydrogel of about 3 to 8-fold, reaching 18 kPa at 0% strain and 62 kPa at 20% strain for the hydrogel with the highest NFC content. All hydrogels presented a porous and homogeneous structure, with interconnected pore cells of around 100 nm in diameter. The hydrogels are biocompatible. The results of this study demonstrate that composite hydrogels reinforced with NFC may be viable as nucleus pulposus implant due to their adequate swelling ratio that may restore annulus fibrosus loading and their increased mechanical properties that could possibly restore the height of intervertebral discs.

  • 319.
    Boström, Karin
    KTH, Skolan för kemivetenskap (CHE).
    Tillförsel av jäst till SSF i industriell skala2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Användning av etanol som drivmedel och en efterfråga på gröna kemikalier driver utvecklingen av bioetanol framåt. Etanolpiloten, SEKAB, i Örnsköldsvik är en av få anläggningar i världen med kompetens och kunskap att producera bioetanol baserat på lignocellulosa. På senare tid har det dock uppstått problem vid etanolframställningen på grund av att en del jästodlingar blivit kontaminerade av bakterier vilket lett till ett sämre utbyte av biomassa och etanol. Det huvudsakliga syftet med detta examensarbete var att ta reda på orsaken till dessa misslyckade jästodlingar.

     

    Examensarbetet delades upp i två huvudsakliga problemområden. Förutom orsaken till de kontaminerade odlingarna studerades även funktionen hos en ny jäststam, Saccaromyces cerevisiae torrjäst, i syfte att undersöka om det finns bättre alternativ till den jäststam som används i etanopiloten i nuläget.

     

    En specialstudie av rengöringen av odlingstankar och ledningar i etanolpiloten utfördes i syfte att kartlägga var i utrustningen som infektionsrisken är som störst. Försöken påvisade att det huvudsakliga problemet kan lokaliseras till den största jästodlingstanken. Där befinner sig jästen under en längre tid i en miljö som är gynnsam för tillväxt av både jäst och bakterier. En annan orsak till de infekterade odlingarna är att rengöringen av utrustningen inte har skett på rätt sätt, samt att temperaturen hos tvättkemikalierna har varit för låg. En viktig slutsats är därför att bättre rutiner vid hanteringen av jästodlingsutrustningen samt att större noggrannhet i samband med rengöringen bör eftersträvas.

     

    En bidragande orsak till de infekterade odlingarna kan också härröra från uppodlingsprocessen av ympjäst som i dagens läge sker på laboratorium. Genom att använda en stam av S. cerevisiae som köps in i frystorkad form kan flera steg i jästodlingsprocessen elimineras. Det både förkortar odlingsprocessen och minskar infektionsrisken. S. cerevisiae torrjäst undersöktes både i laboratorium och i etanolpiloten. Tre olika odlingsskalor användes, skakflaskor (250 ml), labfermentorer (3 l) och pilotskala (10m3). Försöken påvisar höga utbyten av både biomassa och etanol. För att kunna hålla nere produktionskostnaderna för etanolframställningen är det viktigt att jästen som används går att odla på det hydrolysat som produceras vid förbehandlingen av råvaran. Försök i pilotskala visar på lovande resultat vid uppodling av S. cerevisiae torrjäst när hela 70 % av sockerkällan kommer från hydrolysat. Ytterligare utvärdering och optimering av odlingsprocessen samt en ekonomisk jämförelse mellan de tillgängliga jäststammarna krävs dock innan S. cerevisiae torrjäst eventuellt kan användas kontinuerligt i pilotskala. 

  • 320. Bourbeillon, Julie
    et al.
    Orchard, Sandra
    Benhar, Itai
    Borrebaeck, Carl
    de Daruvar, Antoine
    Duebel, Stefan
    Frank, Ronald
    Gibson, Frank
    Gloriam, David
    Haslam, Niall
    Hiltker, Tara
    Humphrey-Smith, Ian
    Hust, Michael
    Juncker, David
    Koegl, Manfred
    Konthur, Zoltan
    Korn, Bernhard
    Krobitsch, Sylvia
    Muyldermans, Serge
    Nygren, Per-Åke
    KTH, Skolan för bioteknologi (BIO), Molekylär Bioteknologi. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Palcy, Sandrine
    Polic, Bojan
    Rodriguez, Henry
    Sawyer, Alan
    Schlapshy, Martin
    Snyder, Michael
    Stoevesandt, Oda
    Taussig, Michael J.
    Templin, Markus
    Uhlén, Matthias
    KTH, Skolan för bioteknologi (BIO), Proteomik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    van der Maarel, Silvere
    Wingren, Christer
    Hermjakob, Henning
    Sherman, David
    Minimum information about a protein affinity reagent (MIAPAR)2010Ingår i: Nature Biotechnology, ISSN 1087-0156, E-ISSN 1546-1696, Vol. 28, nr 7, s. 650-653Artikel i tidskrift (Övrigt vetenskapligt)
  • 321.
    Bowman, Lawrence E.
    et al.
    Michigan State University.
    Berglund, Kris
    Nocera, Daniel G.
    Michigan State University.
    A single photon timing instrument that covers a broad temporal range in the reversed timing configuration1993Ingår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 64, nr 2, s. 338-341Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A versatile single-photon timing instrument based on the reversed timing configuration has been constructed. Unlike similar instruments, the apparatus described here is capable of recording a broad range of excited-state decay times owing to a switched fiber optic delay. This allows the user to readily collect time-resolved luminescence data over a variable time window in the reversed-timing configuration. With proper adjustment of the appropriate components, one can acquire a luminescence decay over a variable time range from less than 1 ns to nearly 1 μs. The full width at half-maximum of the instrument response function is 42 ps. The utility of a switched fiber optic delay is discussed and the device's construction is described.

  • 322.
    Bozic, Mojca
    et al.
    Faculty of Mechanical Engineering, Institute for Engineering Materials and Design, University of Maribor.
    Liu, Peng
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Kokol, Vanja
    Faculty of Mechanical Engineering, Institute for Engineering Materials and Design, University of Maribor.
    Enzymatic phosphorylation of cellulose nanofibers to new highly-ions adsorbing, flame-retardant and hydroxyapatite-growth induced natural nanoparticles2014Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, nr 4, s. 2713-2726Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study confirms the enzyme-mediated phosphorylation of cellulose nanofibers (CNF) by using hexokinase and adenosine-5’-triphosphate (ATP) in the presence of Mg-ions, resulting in a phosphate group’s creation predominantly at C-6-O positioned hydroxyl groups of cellulose monomer rings. A proof-of-concept is provided using 12C CPMAS, 31P MAS NMR, ATR-FTIR and XPS analyzing methods. The degree of substitution is determined for the first time by ATR-FTIR spectroscopy being in a correlation with XPS and potentiometric titration results. From the thermal degradation measurements using TGA, the C-6-O phosphorylation was found to noticeably prevent the CNF derivatives from weight loss in the pyrolysis process, thus, providing them flame-resistance functionality. Furthermore, phosphorylation significantly enhanced adsorption capacity of Fe3+ ions making them interesting for fabrication of biobased filters and membranes. Finally, the biomimetic growth of Ca-P crystals (hydroxyapatite) in simulated body fluid was characterized by SEM and showing further practicability for biomedical materials.

  • 323. Bracher, Jasmine M.
    et al.
    Martinez-Rodriguez, Oscar A.
    Dekker, Wijb JC
    Verhoeven, Maarten D.
    van Maris, Antonius
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Pronk, Jack T.
    Reassessment of requirements for anaerobic xylose fermentation by engineered, non-evolved Saccharomyces cerevisiae strains2019Ingår i: FEMS yeast research (Print), ISSN 1567-1356, E-ISSN 1567-1364, Vol. 19, nr 1, artikel-id foy104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Expression of a heterologous xylose isomerase, deletion of the GRE3 aldose-reductase gene and overexpression of genes encoding xylulokinase (XKS1) and non-oxidative pentose-phosphate-pathway enzymes (RKI1, RPE1, TAL1, TKL1) enables aerobic growth of Saccharomyces cerevisiae on d-xylose. However, literature reports differ on whether anaerobic growth on d-xylose requires additional mutations. Here, CRISPR-Cas9-assisted reconstruction and physiological analysis confirmed an early report that this basic set of genetic modifications suffices to enable anaerobic growth on d-xylose in the CEN.PK genetic background. Strains that additionally carried overexpression cassettes for the transaldolase and transketolase paralogs NQM1 and TKL2 only exhibited anaerobic growth on d-xylose after a 7-10 day lag phase. This extended lag phase was eliminated by increasing inoculum concentrations from 0.02 to 0.2 g biomass L-1. Alternatively, a long lag phase could be prevented by sparging low-inoculum-density bioreactor cultures with a CO2/N-2-mixture, thus mimicking initial CO2 concentrations in high-inoculum-density, nitrogen-sparged cultures, or by using l-aspartate instead of ammonium as nitrogen source. This study resolves apparent contradictions in the literature on the genetic interventions required for anaerobic growth of CEN.PK-derived strains on d-xylose. Additionally, it indicates the potential relevance of CO2 availability and anaplerotic carboxylation reactions for anaerobic growth of engineered S. cerevisiae strains on d-xylose.

  • 324.
    Brandin, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Usage of Biofuels in Sweden2013Ingår i: CSR-2 Catalyst for renewable sources: Fuel, Energy, Chemicals Book of Abstracts / [ed] Vadim Yakovlev, Boreskov Institute of Catalysis, Novosibrisk, Russia: Boreskov Institute of Catalysis , 2013, s. 5-7Konferensbidrag (Refereegranskat)
    Abstract [en]

    In Sweden, biofuels have come into substantial use, in an extent that are claimed to be bigger than use of fossil oil. One driving force for this have been the CO2-tax that was introduced in 1991 (1). According to SVEBIO:s calculations (2) based on the Swedish Energy Agency´s prognosis, the total energy consumption in Sweden 2012 was 404 TWh. If the figure is broken down on the different energy sources (figure 1) one can see that the consumption roughly distribute in three different, equally sized, blocks, Biofuels, fossil fuels and water & nuclear power. The major use of the fossil fuels is for transport and the water & nuclear power is used as electric power. The main use of the biofuels is for heating in the industrial sector and as district heating. In 2009 the consumption from those two segments was 85 TWh, and 10 TWh of bio power was co-produced giving an average biomass to electricity efficiency of 12%. This indicates a substantial conversion potential from hot water production to combined heat and power (CHP) production. in Sweden 2013 broken down on the different energy sources. In 2006 the pulp, paper and sawmill industry accounted for 95% of the bio energy consumption in the industrial sector, and the major biofuel consumed was black liquor (5). However, the pulp and paper industries also produced the black liquor in their own processes. The major energy source (58%) for district heating during 2006 was woody biomass (chips, pellets etc.) followed by waste (24%), peat (6%) and others (12%) (5). The use of peat has probably decreased since 2006 since peat is no longer regarded as a renewable energy source. While the use of biofuel for heating purpose is well developed and the bio-power is expected to grow, the use in the transport sector is small, 9 TWh or 7% in 2011. The main consumption there is due to the mandatory addition (5%) of ethanol to gasoline and FAME to diesel (6). The Swedish authorities have announced plans to increase the renewable content to 7.5 % in 2015 on the way to fulfill the EU’s goal of 10 % renewable transportation fuels in 2020. However the new proposed fuel directive in EU says that a maximum of 5% renewable fuel may be produced from food sources like sugars and vegetable oils. Another bothersome fact is that, in principle, all rape seed oil produced in Sweden is consumed (95-97%) in the food sector, and consequently all FAME used (in principle) in Sweden is imported as FAME, rape seed oil or seed (6). In Sweden a new source of biodiesel have emerged, tall oil diesel. Tall oil is extracted from black liquor and refined into a diesel fraction (not FAME) and can be mixed into fossil diesel, i.e. Preem Evolution diesel. The SUNPINE plant in Piteå have a capacity of 100 000 metric tons of tall oil diesel per annum, while the total potential in all of Sweden is claimed to be 200 000 tons (7). 100 000 tons of tall oil corresponds to 1% of the total diesel consumption in Sweden. in Sweden for 2010 and a prognosis for 2014. (6). Accordingly, the profoundest task is to decrease the fossil fuel dependency in the transport sector, and clearly, the first generation biofuels can´t do this on its own. Biogas is a fuel gas with high methane content that can be used in a similar way to natural gas; for instance for cooking, heating and as transportation fuel. Today biogas is produced by fermentation of waste (municipal waste, sludge, manure), but can be produced by gasification of biomass, for instance from forest residues such as branches and rots (GROT in Swedish). To get high efficiency in the production, the lower hydrocarbons, mainly methane, in the producer gas, should not be converted into synthesis gas. Instead a synthesis gas with high methane content is sought. This limits the drainage of chemically bonded energy, due to the exothermic reaction in the synthesis step (so called methanisation). In 2011 0.7 TWh of biogas was produced in Sweden by fermentation of waste (6) and there were no production by gasification, at least not of economic importance. The potential seems to be large, though. In 2008 the total potential for biogas production, in Sweden, from waste by fermentation and gasification was estimated to 70 TWh (10 TWh fermentation and 60 TWh gasification) (8). This figure includes only different types of waste and no dedicated agricultural crops or dedicated forest harvest. Activities in the biogas sector, by gasification, in Sweden are the Göteborgs energi´s Gobigas project in Gothenburg and Eon´s Bio2G-project, now pending, in south of Sweden. If the producer gas is cleaned and upgraded into synthesis gas also other fuels could be produced. In Sweden methanol and DME productions are planned for in the Värmlands metanol-project and at Chemrecs DME production plant in Piteå.

  • 325.
    Brandin, Jan
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Hulteberg, Christian
    Lunds Tekniska Högskola .
    Leveau, Andreas
    Biofuel-Solutions AB.
    Selective Catalysts for Glycerol Dehydration2013Ingår i: CRS-2, Catalysis for Renewable Sources: Fuel,Energy,ChemicalsBook of Abstracts / [ed] Vadim Yakovlev, Boreskov Institute of Catalysis, Novosibirsk, Russia: Boreskov Institute of Catalysis , 2013, s. 17-18Konferensbidrag (Refereegranskat)
    Abstract [en]

     There has been an increased interest over the last decade for replacing fossil based feedstock’s with renewable ones. There are several such feedstock’s that are currently being investigated such as cellulose, lignin, hemicellulose, triglycerides etc. However, when trying to perform selective reactions an as homogeneous feedstock as possible is preferable. One such feedstock example is glycerol, a side-product from biofuels production, which is a tri-alcohol and thus has much flexibility for reactions, e.g. dehydration, hydrogenation, addition reactions etc. Glycerol in itself is a good starting point for fine chemicals production being non-toxic and available in rather large quantities [1-2]. A key reaction for glycerol valorisation is the dehydration of glycerol to form acrolein, an unsaturated C3 aldehyde, which may be used for producing acrylic acid, acrylonitrile and other important chemcial products. It has recently been shown that pore-condensation of glycerol is an issue under industrial like conditions, leading to liquid-phase reactions and speeding up the catalyst activity and selectivity loss [3]. To address this issue, modified catalyst materials have been prepared where the relevant micro and meso pores have been removed by thermal sintering; calculations have shown that pores below 45 Å may be subject to pore condensation. The catalyst starting material was a 10% WO3 by weight supported on ZrO2 in the form of beads 1–2 mm and it was thermally treated at 400°C, 500°C, 600°C, 700°C, 700°C, 800°C, 850°C, 900°C and 1000°C for 2 hours. The catalysts were characterised using nitrogen adsorption, mercury intrusion porosimetry (MIP), Raman spectroscopy and ammonia temperature programmed desorption. The thermal sintered catalysts show first of all a decreasing BET surface area with sintering commencing between 700°C and 800°C when it decreases from the initial 71 m2/g to 62 m2/g and at 1000°C there is a mere 5 m2/g of surface area left. During sintering, the micro and meso-porosity is reduced as evidenced by MIP and depicted in figure 1. As may be seen in the figure, sintering decrease the amount of pores below and around 100 Å is reduced at a sintering temperature of 800°C and above. The most suitable catalyst based on the MIP appears to be the one sintered at 850°C which is further strengthened by the Raman analysis. There is a clear shift in the tungsten structure from monoclinic to triclinic between 850°C and 900°C and it is believed that the monoclinic phase is important for activity and selectivity. Further, the heat treatment shows that there is an increase in catalyst acidity measured as mmol NH3/(m2/g) but a decrease in the acid strength as evidenced by a decrease in the desorption peak maximum temperature.

     

  • 326.
    Brandin, Jan
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Odenbrand, Ingemar
    Lund University .
    Poisoning of SCR Catalysts used in Municipal Waste Incineration Applications2017Ingår i: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 60, nr 17-18, s. 1306-1316Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A commercial vanadia, tungsta on titania SCRcatalyst was poisoned in a side stream in a waste incinerationplant. The effect of especially alkali metal poisoningwas observed resulting in a decreased activity at long timesof exposure. The deactivation after 2311 h was 36% whilethe decrease in surface area was only 7.6%. Thus the majorcause for deactivation was a chemical blocking of acidicsites by alkali metals. The activation–deactivation modelshowed excellent agreement with experimental data. Themodel suggests that the original adsorption sites, fromthe preparation of the catalyst, are rapidly deactivated butare replaced by a new population of adsorption sites dueto activation of the catalyst surface by sulphur compounds(SO2, SO3)in the flue gas.

  • 327.
    Brandin, Jan
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Tunér, Martin
    Lunds Tekniska Högskola.
    Odenbrand, Ingemar
    Lunds Tekniska Högskola.
    Small Scale Gasifiction: Gas Engine CHP for Biofuels2011Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    I ett gemensamt projekt har Linnéuniversitetet i Växjö och Lunds Tekniska Högskola, på uppdrag av Energimyndigheten, genomfört en inventering av teknik och system för småskalig kombinerad värme och kraft produktion via förgasare-gasmotor teknik. Definitionen för småskalighet i denna studie, är anläggningar med en termisk effekt upp till 10 MW(3 MWel) och där bränslet är någon form av biomassa, vanligtvis träbaserad (trä eller skogsavfall) i form av flis, pellets eller spån.

    Projektrapporten innehåller först en deskriptiv del över teknikens ståndpunkt inom småskalig förgasning, gasrening och gasmotorer. Den andra delen utgörs av en fallbeskrivning för de olika anläggningarna som ingår i studien.

    • MEVA Innovations VIPP-VORTEX CHP anläggning
    • DTU:s VIKING CHP anläggning
    • Bio-kraftverket i Güssing
    • Harboøre CHP anläggning
    • Skive CHP anläggning

    I fallbeskrivningarna gås anläggningarnas särdrag, funktioner samt enhetsoperationer igenom, samt vilken typ av bränsle som används och vilka verkningsgrader som uppnås. Investerings- och driftskostnaderna, där sådana är tillgängliga, presenteras tillsammans med uppgifter på anläggningarnas tillgänglighet. Även en internationell utblick, huvudsakligen fokuserad på utvecklingsländer, har genomförts.   

    Generellt sett är tekniken tillräckligt mogen för kommersialisering. Det finns dock en del enhetsoperationer, t.ex. tjärkrackning och tjärreformering, som behöver fortsatt forskning och utveckling. Fortsatt utveckling av systemen kommer förmodligen att göra prestandan för anläggningarna än mera lika och öka elverkningsgraden till 30-40 % med en total verkningsgrad runt 90 %.

    Harboøre-, Güssing- och Skiveanläggningarna är avsedda som kommunala kraft-värmeanläggningar medan Viking och VIPP-VORTEX är avsedda att ersätta mindre varmvattencentraler i fjärrvärmenätet. Bimass Gasification Group DTU och MEVA Innovation har också identifierat en potentiellt stor marknad i utvecklingsländer i Asien.     

    Förslag till områden för fortsatt forsknings och utvecklingsarbete:

    • Gasrening/Gasuppgradering
    • Användning av producerat värme
    • System integration/optimering
    • Småskalig syre-produktion
    • Vidareutveckling av gasmotorer
  • 328.
    Branneby, Cecilia
    et al.
    Cambrex Karlskoga AB.
    Svedendahl, Maria
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Lipase-Catalyzed Aldol and Michael-Type Reactions2006Konferensbidrag (Refereegranskat)
  • 329.
    Branneby, Cecilia
    et al.
    Cambrex Karlskoga AB.
    Svedendahl, Maria
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Lipase-Catalyzed Aldol and Michael-Type Reactions2005Ingår i: Book of abstracts, 2005Konferensbidrag (Refereegranskat)
  • 330.
    Brechmann, Nils Arnold
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi. AdBIOPRO, VINNOVA Competence Centre for Advanced BioProduction by Continuous Processing, Stockholm, Sweden.
    Eriksson, Per-Olov
    Eriksson, Kristofer
    Oscarsson, Sven
    Buijs, Jos
    Shokri, Atefeh
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi. AdBIOPRO, VINNOVA Competence Centre for Advanced BioProduction by Continuous Processing, Stockholm, Sweden.
    Hjälm, Göran
    Chotteau, Véronique
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi. AdBIOPRO, VINNOVA Competence Centre for Advanced BioProduction by Continuous Processing, Stockholm, Sweden.
    Pilot-scale process for magnetic bead purification of antibodies directly from non-clarified CHO cell culture2019Ingår i: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High capacity magnetic protein A agarose beads, LOABeads PrtA, were used in the development

    of a new process for affinity purification of monoclonal antibodies (mAbs) from non-clarified

    CHO cell broth using a pilot-scale magnetic separator. The LOABeads had a maximum binding

    capacity of 65 mg/mL and an adsorption capacity of 25–42 mg IgG/mL bead in suspension for an

    IgG concentration of 1 to 8 g/L. Pilot-scale separation was initially tested in a mAb capture step

    from 26 L clarified harvest. Small-scale experiments showed that similar mAb adsorptions were

    obtained in cell broth containing 40 Å~ 106 cells/mL as in clarified supernatant. Two pilot-scale

    purification runs were then performed on non-clarified cell broth from fed-batch runs of 16 L,

    where a rapid mAb adsorption ≥96.6% was observed after 1 h. This process using 1 L of magnetic beads had an overall mAb yield of 86% and 16 times concentration factor. After this single protein

    A capture step, the mAb purity was similar to the one obtained by column chromatography, while

    the host cell protein content was very low, <10 ppm. Our results showed that this magnetic bead

    mAb purification process, using a dedicated pilot-scale separation device, was a highly efficient

    single step, which directly connected the culture to the downstream process without cell clarification.

    Purification of mAb directly from non-clarified cell broth without cell separation can provide

    significant savings in terms of resources, operation time, and equipment, compared to legacy procedure of cell separation followed by column chromatography step.

  • 331. Brennan, Donal J.
    et al.
    Laursen, Henriette
    O'Connor, Darran P.
    Borgquist, Signe
    Uhlén, Mathias
    KTH, Skolan för bioteknologi (BIO), Proteomik.
    Gallagher, William M.
    Ponten, Fredrik
    Millikan, Robert C.
    Ryden, Lisa
    Jirström, Karin
    Tumor-specific HMG-CoA reductase expression in primary premenopausal breast cancer predicts response to tamoxifen2011Ingår i: Breast Cancer Research, ISSN 1465-5411, E-ISSN 1465-542X, Vol. 13, nr 1, s. R12-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Introduction: We previously reported an association between tumor-specific 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMG-CoAR) expression and a good prognosis in breast cancer. Here, the predictive value of HMG-CoAR expression in relation to tamoxifen response was examined. Methods: HMG-CoAR protein and RNA expression was analyzed in a cell line model of tamoxifen resistance using western blotting and PCR. HMG-CoAR mRNA expression was examined in 155 tamoxifen-treated breast tumors obtained from a previously published gene expression study (Cohort I). HMG-CoAR protein expression was examined in 422 stage II premenopausal breast cancer patients, who had previously participated in a randomized control trial comparing 2 years of tamoxifen with no systemic adjuvant treatment (Cohort II). Kaplan-Meier analysis and Cox proportional hazards modeling were used to estimate the risk of recurrence-free survival (RFS) and the effect of HMG-CoAR expression on tamoxifen response. Results: HMG-CoAR protein and RNA expression were decreased in tamoxifen-resistant MCF7-LCC9 cells compared with their tamoxifen-sensitive parental cell line. HMG-CoAR mRNA expression was decreased in tumors that recurred following tamoxifen treatment (P < 0.001) and was an independent predictor of RFS in Cohort I (hazard ratio = 0.63, P = 0.009). In Cohort II, adjuvant tamoxifen increased RFS in HMG-CoAR-positive tumors (P = 0.008). Multivariate Cox regression analysis demonstrated that HMG-CoAR was an independent predictor of improved RFS in Cohort II (hazard ratio = 0.67, P = 0.010), and subset analysis revealed that this was maintained in estrogen receptor (ER)-positive patients (hazard ratio = 0.65, P = 0.029). Multivariate interaction analysis demonstrated a difference in tamoxifen efficacy relative to HMG-CoAR expression (P = 0.05). Analysis of tamoxifen response revealed that patients with ER-positive/HMG-CoAR tumors had a significant response to tamoxifen (P = 0.010) as well as patients with ER-positive or HMG-CoAR-positive tumors (P = 0.035). Stratification according to ER and HMG-CoAR status demonstrated that ER-positive/HMG-CoAR-positive tumors had an improved RFS compared with ER-positive/HMG-CoAR-negative tumors in the treatment arm (P = 0.033); this effect was lost in the control arm (P = 0.138), however, suggesting that HMG-CoAR predicts tamoxifen response. Conclusions: HMG CoAR expression is a predictor of response to tamoxifen in both ER-positive and ER-negative disease. Premenopausal patients with tumors that express ER or HMG-CoAR respond to adjuvant tamoxifen.

  • 332.
    Broberg, Anders
    et al.
    Department of Chemistry, Swedish University of Agricultural Sciences, Sweden.
    Jacobsson, Karin
    Department of Microbiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Ström, Katrin
    Department of Microbiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Schnürer, Johan
    Department of Microbiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Metabolite profiles of lactic acid bacteria in grass silage2007Ingår i: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 73, nr 17, s. 5547-5552Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The metabolite production of lactic acid bacteria JAB) on silage was investigated. The aim was to compare the production of antifungal metabolites in silage with the production in liquid cultures previously studied in our laboratory. The following metabolites were found to be present at elevated concentrations in silos inoculated with LAB strains: 3-hydroxydecanoic acid, 2-hydroxy-4-methylpentanoic acid, benzoic acid, catechol, hydrocinnamic acid, salicylic acid, 3-phenyllactic acid, 4-hydroxybenzoic acid, (trans, trans)-3,4-dihydroxycyclohexane-1-carboxylic acid, p-hydrocoumaric acid, vanillic acid, azelaic acid, hydroferulic acid, p-coumaric acid, hydrocaffeic acid, ferulic acid, and caffeic acid. Among these metabolites, the antifungal compounds 3-phenyllactic acid and 3-hydroxydecanoic acid were previously isolated in our laboratory from liquid cultures of the same LAB strains by bioassay-guided fractionation. It was concluded that other metabolites, e.g., p-hydrocoumaric acid, hydroferulic acid, and p-coumaric acid, were released from the grass by the added LAB strains. The antifungal activities of the identified metabolites in 100 mM lactic acid were investigated. The MICs against Pichia anomala, Penicillium roqueforti, and Aspergillus fumigatus were determined, and 3-hydroxydecanoic acid showed the lowest MIC (0.1 mg ml(-1) for two of the three test organisms).

  • 333.
    Broström, Markus
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Holmgren, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Ash fractionation and slag formation during entrained flow biomass gasification2018Konferensbidrag (Övrigt vetenskapligt)
  • 334.
    Brumer, Harry
    et al.
    KTH, Tidigare Institutioner, Bioteknologi.
    Zhou, Qi
    KTH, Tidigare Institutioner, Bioteknologi.
    Baumann, Martin J.
    KTH, Tidigare Institutioner, Bioteknologi.
    Carlsson, Kjell
    KTH, Tidigare Institutioner, Bioteknologi.
    Teeri, Tuula
    KTH, Tidigare Institutioner, Bioteknologi.
    Activation of crystalline cellulose surfaces though the chemoenzymatic modification of xyloglucan2004Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, nr 18, s. 5715-1721Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose constitutes an important raw material for many industries. However, the superb load-bearing properties of cellulose are accompanied by poor chemical reactivity. The hydroxyl groups on cellulose surfaces can be reacted but usually not without loss of fiber integrity and strength. Here, we describe a novel chemoenzymatic approach for the efficient incorporation of chemical functionality onto cellulose surfaces. The modification is brought about by using a transglycosylating enzyme, xyloglucan endotranglycosylase, to join chemically modified xyloglucan oligosaccharides to xyloglucan, which has a naturally high affinity to cellulose. Binding of the chemically modified hemicellulose molecules can thus be used to attach a wide variety of chemical moieties without disruption of the individual fiber or fiber matrix.

  • 335.
    Brunow, G.
    et al.
    University of Helsinki.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Lundquist, K.
    Chalmers University of Technology.
    Sipilä, J.
    University of Helsinki.
    On the distribution of the diastereomers of the structural elements in lignins: the steric course of reactions mimicking lignin biosynthesis1993Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 27, nr 4, s. 281-286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stereochemical studies on the formation of the diastereomers of arylglycerol-β-aryl ether structures during lignin biosynthesis have been carried out with model compounds. The addition of water to quinone methides of the β-syringyl ether type gives arylglycerol β-syringyl ethers with a predominance of the erythro isomer when the pH of the medium is low. Since erythro forms of arylglycerol β-syringyl ethers are prevalent in hardwood lignins, this indicates that the pH of the medium in which lignin biosynthesis occurs is lower than has been assumed until now. Equilibration studies with non-phenolic model compounds of the arylglycerolβ-guaiacyl ether and β-syringyl ether types under acidolysis conditions indicate that the erythro predominance observed in the syringyl ethers in lignins does not correspond to equilibrium conditions. A remarkable resistance to acidolysis is observed in the model compounds of etherified syringylglycerol β-syringyl ether type.

  • 336.
    Bruns, Volker
    et al.
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Redovisning och finansiering.
    Holland, Dan
    Jon M. Huntsman School of Business, Utah State University, United States .
    Shepherd, Dean A.
    Kelley School of Business, Indiana University, Bloomington, IN, United States.
    Wiklund, Johan
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, EMM (Entreprenörskap, Marknadsföring, Management). Högskolan i Jönköping, Internationella Handelshögskolan, JIBS Entrepreneurship Centre. Department of Entrepreneurship and Emerging Enterprises, Whitman School of Management, Syracuse University, United States.
    The role of human capital in loan officers' decision policies2016Ingår i: Decision making in entrepreneurship: selected joint papers of Dean A. Shepherd / [ed] Dean A Shepherd, Edward Elgar Publishing, 2016, s. 315-336Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Using a human-capital perspective and the similarity-attraction paradigm, we examine the role of general and specific human capital in the decision policies of 114 Swedish loan officers in their assessments of small-business loan requests. We found that human capital characteristics had marginal impact on decision policy contingencies and that specific human capital had no significant influence on the probability of loan approval. However, we did find that the similarity between the loan officers’ human capital and the pplicants’ human capital was a significant indicator of loan approval. The findings offer interesting insight into the heterogeneity of loan decision processes and outcomes and future research opportunities are suggested.

  • 337.
    Bruns, Volker
    et al.
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Redovisning och finansiering.
    Holland, Dan
    Shepherd, Dean
    Wiklund, Johan
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, EMM (Entreprenörskap, Marknadsföring, Management). Högskolan i Jönköping, Internationella Handelshögskolan, JIBS Entrepreneurship Centre.
    The role of human capital in loan officers' decision policies2008Ingår i: Entrepreneurship: Theory & Practice, ISSN 1042-2587, E-ISSN 1540-6520, Vol. 32, nr 3, s. 485-506Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using a human-capital perspective and the similarity-attraction paradigm, we examine the role of general and specific human capital in the decision policies of 114 Swedish loan officers in their assessments of small-business loan requests. We found that human capital characteristics had marginal impact on decision policy contingencies and that specific human capital had no significant influence on the probability of loan approval. However, we did find that the similarity between the loan officers’ human capital and the pplicants’ human capital was a significant indicator of loan approval. The findings offer interesting insight into the heterogeneity of loan decision processes and outcomes and future research opportunities are suggested.

  • 338.
    Bulota, Mindaugas
    et al.
    Department of Forest Products Technology, School of Chemical Technology, Aalto University.
    Tanpichai, Supachok
    Materials Science Centre, School of Materials, School of Materials, University of Manchester.
    Hughes, Mark R.
    Department of Forest Products Technology, School of Chemical Technology, Aalto University.
    Eichhorn, Stephen J.
    College of Engineering, Mathematics and Physical Sciences, University of Exeter.
    Micromechanics of TEMPO-oxidized fibrillated cellulose composites2012Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 4, nr 1, s. 331-337Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Composites of poly(lactic) acid (PLA) reinforced with TEMPO-oxidized fibrillated cellulose (TOFC) were prepared to 15, 20, 25, and 30% fiber weight fractions. To aid dispersion and to improve stress transfer, we acetylated the TOFC prior to the fabrication of TOFC-PLA composite films. Raman spectroscopy was employed to study the deformation micromechanics in these systems. Microtensile specimens were prepared from the films and deformed in tension with Raman spectra being collected simultaneously during deformation. A shift in a Raman peak initially located at ∼1095 cm -1, assigned to C-O-C stretching of the cellulose backbone, was observed upon deformation, indicating stress transfer from the matrix to the TOFC reinforcement. The highest band shift rate, with respect to strain, was observed in composites having a 30% weight fraction of TOFC. These composites also displayed a significantly higher strain to failure compared to pure acetylated TOFC film, and to the composites having lower weight fractions of TOFC. The stress-transfer processes that occur in microfibrillated cellulose composites are discussed with reference to the micromechanical data presented. It is shown that these TOFC-based composite materials are progressively dominated by the mechanics of the networks, and a shear-lag type stress transfer between fibers.

  • 339. Buss, Wolfram
    et al.
    Jansson, Stina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wurzer, Christian
    Masek, Ondrej
    Synergies between BECCS and Biochar-Maximizing Carbon Sequestration Potential by Recycling Wood Ash2019Ingår i: ACS SUSTAINABLE CHEMISTRY & ENGINEERING, ISSN 2168-0485, Vol. 7, nr 4, s. 4204-4209Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bioenergy carbon capture and storage (BECCS) and biochar are key carbon-negative technologies. In this study, synergies between these technologies were explored by using ash from wood combustion, a byproduct from BECCS, as an additive (0, 5, 10, 20, and 50 wt %) in biochar production (wood pyrolysis at 450 degrees C). The addition of wood ash catalyzed biochar formation and increased the yield of fixed carbon (FC) (per dry, ash-free feedstock), i.e., the sequestrable carbon per spruce wood input. At the highest ash addition (50%), 45% less wood was needed to yield the same amount of FC. Since the land area available for growing biomass is becoming scarcer, our approach significantly increases biochar's potential to sequester carbon. However, increasing the feedstock ash content results in less feedstock carbon available for conversion into FC. Consequently, the yield of FC per pyrolysis run (based on dry feedstock) in the 50% ash-amended material was lower than in the control. An economic analysis showed that the 20% ash-amended biochar brings the biggest cost savings over the control with a 15% decrease in CO2-abatement costs. Biochar-ash composites increase the carbon sequestration potential of biochar significantly, reduce the CO2-abatement costs, and recycle nutrients which can result in increased plant growth in turn and more biomass for BECCS, bringing synergies for BECCS and biochar deployment.

  • 340.
    Butylina, Svetlana
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Polypropylene (PP)-Based Hybrid Biocomposites and Bionanocomposites2018Ingår i: Polypropylene-Based Biocomposites and Bionanocomposites / [ed] P. M. Visakh, Matheus Poletto, NJ, USA.: John Wiley & Sons, 2018, s. 113-144Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Hybrid biocomposites and particularly hybrid bionanocomposites are relatively recent additions to the composite family. Biocomposites are composite materials which include parts of biological origin. Hybridization is very useful because it makes it possible to tailor the composite properties according to the desired structure. This chapter deals with the preparation methods applied for PP-based hybrid biocomposites and bionanocomposites. The mechanical and thermal properties as well as the weathering properties and fire performance of various hybrid composites are summarized. The properties of hybrid biocomposites depend on the nature, size and loading of the filler and its interaction with the PP matrix. In most cases, commercial use of biocomposites has been limited to nonstructural or semistructural applications due to low stiffness, impact and thermal properties. Hybridization helps to overcome these problems. Nanofillers can improve the thermal stability, flame retardancy and durability, and therefore give rise to new applications and extend the existing applications of PP-based biocomposites

  • 341.
    Butylina, Svetlana
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Geng, Shiyu
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Properties of as-prepared and freeze-dried hydrogels made from poly(vinyl alcohol) and cellulose nanocrystals using freeze-thaw technique2016Ingår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 81, s. 386-396Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly(vinyl alcohol), PVA hydrogels are potential materials for biomedical and biotechnogical applications. However, their low mechanical properties restrict their use. In this study, the effect of PVA concentration, addition of nanocrystalline cellulose, CNC, number of freeze-thaw cycles and freeze-drying stage on properties of resulting hydrogels were investigated. The results showed that increase in PVA concentration and the addition of CNC improved the compressive properties of the hydrogels. Overall, increase in number of freeze-thaw cycles from 3 to 5 did not show any improvements in properties of hydrogels. Concentration of PVA had great effect on morphology of freeze-dried hydrogels. The CNC reduced crystallinity of PVA/CNC hydrogels as compared to PVA hydrogels. Rehydrated PVA and PVA/CNC hydrogels had higher compressive characteristics than their as-prepared analogues. In general, an improvement of compressive properties of hydrogels was achieved via reduction of their water content. In case of 5% PVA hydrogel, an addition of CNC was found to be beneficial because it increased degree of swelling and water content on rehydration.

  • 342.
    Butylina, Svetlana
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Hyvärinen, Marko
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    A study of surface changes of wood-polypropylene composites as the result of exterior weathering2012Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 97, nr 3, s. 337-345Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Outdoor applications of composites raised questions about their durability. In this study, the effects of outdoor weathering on the properties of wood-polypropylene composites with and without pigments were examined. The composites were placed outdoors for one year, and their colour changes were evaluated after 1, 3, 6, 9 and 12 months of weathering. The weathering resulted in considerable colour fading of the composites. Composites containing darker colour pigments had better colour stability. Scanning electron microscopy analysis revealed that surface cracks caused by weathering in a wood-polypropylene composite having a higher polypropylene content were less abundant, and the deterioration of the surface layer was lower compared to composites containing less polymer. Measurements of melting temperatures by differential scanning calorimetry gave a consistent picture of polypropylene degradation in the surface layer. After weathering, a decrease in Charpy impact strength was found for composites characterised by higher moisture absorption.

  • 343.
    Butylina, Svetlana
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Hyvärinen, Marko
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Accelerated weathering of wood-polypropylene composites containing minerals2012Ingår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 43, nr 11, s. 2087-2094Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Accelerated weathering tests were carried out on wood-polypropylene composites containing minerals. Three different mineral fillers were studied: calcium carbonate, wollastonite and talc. Colour changes were evaluated after distinct periods; the total time of exposure of the composites to UV irradiation was 2000 h. The weathering resulted in significant colour fading of the composites. The composites containing mineral fillers had higher changes of colour (lightness) than the reference composite. Scanning electron microscopy analysis revealed deterioration of the polymer surface layer in all weathered composites. Exposure of the reference composite to UV irradiation resulted in the disappearance of the polypropylene surface layer and disclosure of wood fibres, which led to a higher drop in the lignin content of this composite compared to mineral-containing composites. A substitution of part of the wood with mineral fillers resulted in decreased water absorption and thickness swelling of mineral-containing composites, compared to the reference composite. Exposure to water immersion-freeze-thaw cyclic treatment and UV irradiation led to a decrease in the Charpy impact strength of the composites, except for the composite containing talc

  • 344.
    Butylina, Svetlana
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Department of Mechanical Engineering, Lappeenranta University of Technology .
    Hyvärinen, Marko
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Weathering of wood-polypropylene and wood-wollastonite-polypropylene composites containing pigments in Finnish climatic conditions2015Ingår i: Pigment & Resin Technology, ISSN 0369-9420, E-ISSN 1758-6941, Vol. 44, nr 5, s. 313-321Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose The purpose of this paper is to study the resistance of wood-polypropylene and wood-wollastonite-polypropylene composites containing pigments to natural weathering. Design/methodology/approach Natural weathering of composites was conducted in Finnish climatic conditions for one year. The colour of the composites was determined with a spectrophotometer, the morphology of the composite surface was analysed by scanning electron microscopy (SEM), and the changes in the polymer structure in surface layer of the composites were analysed with differential scanning calorimetry (DSC). Charpy impact strength was determined with an impact tester. Findings The pigments used in this study reduced the colour change of the composites exposed to outdoor weathering as compared with the un-coloured composite. The carbon black pigment was more effective than the iron oxide pigment. Moreover, only the carbon black pigment was found to reduce the degradation of the surface layer of the composites. The addition of the carbon black pigment had a positive effect on the dimensional stability of the composites in a water absorption test. Only the combination of the carbon black pigment and wollastonite resulted in a composite which was capable to retain its Charpy impact strength both after one year of outdoor weathering and cyclic treatment. Research limitations/implications This study is a part of continuous research on the development of wood-polymer composites (WPUs) suitable for outdoor applications in Finnish climatic conditions. The first part of the study, which has been published earlier, showed the results of weathering of composites in accelerated tests in comparison with 1,000 hours outdoor exposure during summer time (June and July). Outdoor weathering limited to 1,000 hours cannot give an objective view on the weathering behaviour of composites in Finnish climatic conditions. The results of the current study were obtained from one-year outdoor exposure of composites. Originality/value The wood-polypropylene composite made with the combination of the carbon black pigment and wollastonite can be recommended for outdoor applications. The study provides useful information on the resistance of wood-polypropylene composites to weathering in Finnish climatic conditions.

  • 345.
    Butylina, Svetlana
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Department of Mechanical Engineering, Lappeenranta University of Technology.
    Hyvärinen, Marko
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Weathering of wood-polypropylene composites containing pigments2012Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 70, nr 5, s. 719-726Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Outdoor applications of composites have raised questions about their durability. In this study, the effects of outdoor weathering on the properties of wood-polypropylene composites with and without pigments were examined. The composites were placed outdoors for one year, and their colour changes were evaluated after 1, 3, 6, 9 and 12 months of weathering. The durability of the composites was assessed by testing flexural strength and density. Scanning electron microscopy was applied to evaluate the surface degradation of the composites. The weathering resulted in considerable colour fading of the composites. The composites containing darker colour pigments had better colour stability. After weathering, the general trend was a decrease of the flexural strength and density of the composites. The decrease in flexural strength was found to be lower for the composites having higher density.

  • 346.
    Butylina, Svetlana
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology, Finland.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology, Finland.
    Resistance to weathering of wood-polypropylene and wood-wollastonite-polypropylene composites made with and without carbon black2014Ingår i: Pigment & Resin Technology, ISSN 0369-9420, E-ISSN 1758-6941, Vol. 43, nr 4, s. 185-193Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose - The purpose of this paper is to study natural and accelerated weathering of wood-polypropylene (WF-PP) and wood-wollastonite-polypropylene composites made with and without carbon black.

    Design/methodology/approach - Natural weathering was conducted in Ruokolahti, Finland in the time of year when solar radiation was maximal. The accelerated weathering tests included exposure to a xenon-arc source with and without spray, and a cyclic test consisting of water immersion-freeze-thaw stages.

    Findings - Both the type of weathering and the formulation of the composite determined the degree of change in their properties. Weathering, including xenon-arc exposure with spray resulted in much higher changes of colour of non-pigmented composites compared to natural weathering or xenon-arc weathering without spray. Both UV irradiation and moisture had an adverse effect on the Charpy impact strength of non-pigmented composites. Carbon black containing composites performed better than non-pigmented composites.

    Research limitations/implications - This study is a part of an ongoing research on the development of wood-polymer composites (WPCs) suitable for outdoor applications in Finnish climatic conditions. Outdoor weathering limited to 1,000 h cannot be used for the prediction of the service life of composites and was used here solely for comparative purposes.

    Originality/value - This paper will help to understand the effect of different weathering factors on the behaviour of WF-PP and wood-wollastonite-polypropylene composites made with and without carbon black (as UV stabiliser). The study demonstrated that while accelerated weathering tests provided useful information on the resistance of WF-PP composites to different weathering factors, they cannot be used alone to predict the behaviour of WPCs meant for outdoor application

  • 347.
    Butylina, Svetlana
    et al.
    Department of Chemical Technology, Lappeenranta University of Technology.
    Luque, Susana
    bDepartment of Chemical and Environmental Engineering, University of Oviedo.
    Nyström, Marianne
    Department of Chemical Technology, Lappeenranta University of Technology.
    Fractionation of whey-derived peptides using a combination of ultrafiltration and nanofiltration2006Ingår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 280, nr 1-2, s. 418-426Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes the fractionation and further isolation and characterisation of peptides and proteins present in sweet whey by means of ultrafiltration using a regenerated cellulose membrane with a nominal molar mass cut-off value of 10 kg/mol and nanofiltration through sulphonated polyether sulphone membrane with a cut-off of 1 kg/mol. The concentration of whey proteins was done below the critical flux. The sieving coefficients for the whey components (proteins, lactose and salts) were estimated. Whey proteins were completely rejected by the ultrafiltration membrane. Size exclusion chromatography (SEC) and matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry were used to evaluate the molar masses of the peptide fractions that were present in the whey permeates. Nanofiltration of whey permeates obtained after ultrafiltration was conducted at two pH values (9.5 and 3.0) that corresponded to the different charged states of the membrane and of the peptides. The transmission of peptides, amino acids and lactose was found to be mainly affected by the permeability of the fouling layer. The selectivity of the nanofiltration membranes toward peptides compared to lactose was calculated as 0.82 and 6.81 at pH 9.5 and 3.0, respectively.

  • 348.
    Butylina, Svetlana
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Martikka, Ossi
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Comparison of water absorption and mechanical properties of wood-plastic composites made from polypropylene and polylactic acid2010Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 5, nr 3-4, s. 220-228Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study focuses on the water absorption and mechanical properties of composites made from softwood sawdust and plastics, such as virgin and recycled polypropylene and polylactic acid (PLA). The composites were processed by extrusion, and their properties were investigated by a water immersion test, mechanical tests and a cyclic test for moisture resistance. Scanning electron microscopy was used to study the morphology of the fracture surfaces of the composites. The composites made with recycled polypropylene had the lowest water absorption and thickness swelling of the studied composites. The PLA composites made with heat-treated sawdust showed the highest flexural strength. Of the polypropylene based composites, virgin polypropylene resulted in composites with higher flexural strength. The Charpy impact strength of the composites was found to have an inverse trend compared to flexural strength. Cyclic treatment of the studied composites resulted in 20-60% loss of flexural strength, depending on type of composite.

  • 349.
    Butylina, Svetlana
    et al.
    Mechanical Engineering, Lappeenranta University of Technology.
    Martikka, Ossi
    Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Mechanical Engineering, Lappeenranta University of Technology.
    Effects of water immersion-freeze-thaw cycling on the properties of wood-polypropylene composites containing pigments2011Ingår i: Pigment & Resin Technology, ISSN 0369-9420, E-ISSN 1758-6941, Vol. 40, nr 6, s. 386-392Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose - The purpose of this paper is to study the effects of water immersion-freeze-thaw treatment on the physical properties, flexural strength (FS) and morphology of wood-polypropylene composites containing pigments. Design/methodology/approach - Wood-polypropylene composites containing brown, green and grey pigments were compounded in a conical twinscrew extruder. A composite manufactured without any pigment addition was used as a reference. The amount of pelletized wood, polypropylene and coupling agent (MAPP) was kept constant. The moisture content, thickness swelling (TS), FS and surface colour of the composites were measured before and after water immersion-freeze-thaw cycling. Scanning electron microscopy (SEM) was used to study the morphology of the composites. Findings - FS and dimensional stability were reduced after exposure to water immersion-freeze-thaw cycling for all composites. The surface properties (colour and roughness) of the composites also changed after exposure to water immersion-freeze-thaw cycling. The degree of change depended on the presence of pigment and the type of polypropylene (neat or recycled), however. Research limitations/implications - This study is a part of an ongoing study on weathering of wood-polymer composites (WPC) containing different additives. The results of this study were obtained from accelerated laboratory experiments. Practical implications - Inorganic pigments are widely used as additives in plastics, because they have an excellent UV absorption, good IR-reflective properties and heat stability. The research revealed that metal-containing pigments had an effect on degradation in quality of wood-polypropylene composites exposed to water immersion-freeze-thaw cyclic treatment. The addition of metal-containing pigments to composite formulation resulted in a higher susceptibility of wood-polypropylene composites to water absorption, and as a consequence to a higher drop of FS compared to composites made without pigment. The polymer matrix plays an important role in the protection of WPC against weathering. Originality/value - This paper will help in understanding possible problems in the durability of wood-polypropylene composites compounded with metal-based pigments when they are exposed to water immersion-freeze-thaw cyclic treatment.

  • 350.
    Butylina, Svetlana
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Martikka, Ossi
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Physical and mechanical properties of wood-polypropylene composites made with virgin and/or recycled polypropylene2011Ingår i: Polymer-plastics technology and engineering (Softcover ed.), ISSN 0360-2559, E-ISSN 1525-6111, Vol. 50, nr 10, s. 1040-1046Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The physical and mechanical properties of wood-polymer composites made with virgin or recycled polypropylene, or a mixture of these were studied. The composites made with recycled polypropylene had higher density, lower porosity, and higher dimensional stability compared to the composites made with virgin polypropylene. Although the composites made with recycled polypropylene exhibited lower tensile strength than those made with virgin polypropylene, they had higher Charpy impact strength. Scanning electron microscopy analysis of the fractured surfaces of the composites showed no significant differences in the fracture mechanisms of the studied composites. The degree of crystallinity was estimated to be higher for the virgin polypropylene than for the recycled one.

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