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  • 1. Abdullah, Muhammad Imran
    et al.
    Janjua, Muhammad Ramzan Saeed Ashraf
    Mahmood, Asif
    Ali, Sajid
    Ali, Muhammad
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Quantum Chemical Designing of Efficient Sensitizers for Dye Sensitized Solar Cells2013In: Bulletin of the Korean Chemical Society (Print), ISSN 0253-2964, E-ISSN 1229-5949, Vol. 34, no 7, 2093-2098 p.Article in journal (Refereed)
    Abstract [en]

    Density functional theory (DFT) was used to determine the ground state geometries of indigo and new design dyes (IM-Dye-1 IM-Dye-2 and IM-Dye-3). The time dependant density functional theory (TDDFT) was used to calculate the excitation energies. All the calculations were performed in both gas and solvent phase. The LUMO energies of all the dyes were above the conduction band of TiO2, while the HOMOs were below the redox couple (except IM-Dye-3). The HOMO-LUMO energy gaps of new design dyes were smaller as compared to indigo. All new design dyes were strongly red shifted as compared to indigo. The improved light harvesting efficiency (LHE) and free energy change of electron injection Delta G(inject) of new designed sensitizers revealed that these materials would be excellent sensitizers. The broken coplanarity between the benzene near anchoring group having LUMO and the last benzene attached to TPA unit in all new design dyes consequently would hamper the recombination reaction. This theoretical designing will the pave way for experimentalists to synthesize the efficient sensitizers for solar cells.

  • 2. Accinelli, Cesare
    et al.
    Saccà, Maria Ludovica
    Batisson, Isabelle
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mencarelli, Mariangela
    Grabic, Roman
    Removal of oseltamivir (Tamiflu) and other selected pharmaceuticals from wastewater using a granular bioplastic formulation entrapping propagules of Phanerochaete chrysosporium2010In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 81, no 3, 436-43 p.Article in journal (Refereed)
    Abstract [en]

    The capacity of the ligninolytic fungus Phanerochaete chrysosporium to degrade a wide variety of environmentally persistent xenobiotics has been largely reported in the literature. Beside other factors, one barrier to a wider use of this bioremediation fungus is the availability of effective formulations that ensure easy preparation, handling and application. In this series of laboratory experiments, we evaluated the efficiency of a granular bioplastic formulation entrapping propagules of P. chrysosporium for removal of four selected pharmaceuticals from wastewater samples. Addition of inoculated granules to samples of the wastewater treatment plant of Bologna significantly increased the removal of the antiviral drug oseltamivir (Tamiflu), and the antibiotics, erythromycin, sulfamethoxazol, and ciprofloxacin. Similar effects were also observed in effluent water. Oseltamivir was the most persistent of the four active substances. After 30d of incubation, approximately two times more oseltamivir was removed in bioremediated wastewater than controls. The highest removal efficiency of the bioplastic formulation was observed with the antibiotic ciprofloxacin. Microbiological DNA-based analysis showed that the bioplastic matrix supported the growth of P. chrysosporium, thus facilitating its adaptation to unusual environment such as wastewater.

  • 3. Acharya, Shravan S.
    et al.
    Easton, Christopher D.
    McCoy, Thomas M.
    Spiccia, Leone
    Ohlin, C. André
    Umeå University, Faculty of Science and Technology, Department of Chemistry. School of Chemistry, Monash University, Clayton, Australia.
    Winther-Jensen, Bjorn
    Diverse composites of metal-complexes and PEDOT facilitated by metal-free vapour phase polymerization2017In: Reactive & functional polymers, ISSN 1381-5148, E-ISSN 1873-166X, Vol. 116, 101-106 p.Article in journal (Refereed)
    Abstract [en]

    Abstract Oxidative polymerization for the manufacture of conducting polymers such as poly(3,4-ethylenedioxy-thiophene) has traditionally employed iron(III) salts. Demonstrated in this study is vapour phase polymerization of 3,4-ethylenedio- xythiophene using a metal-free oxidant, ammonium persulfate, leading to films with an estimated conductivity of 75 S/cm. Additionally, a route for embedding active transition metal complexes into these poly(3,4-ethylenedioxythiophene)/-poly(styrene-4-sulfonate) (PEDOT/PSS) films via vapour assisted complexation is outlined. Here, the vapour pressure of solid ligands around their melting temperatures was exploited to ensure complexation to metal ions added into the oxidant mixture prior to polymerization of PEDOT. Four composite systems are discussed, viz. PEDOT/PSS embedded with tris(8-hydroxyquinolinato)cobalt(III), tris(2,2-bipyridine)cobalt(II), tris(1,10- phenanthroline)cobalt(II) and tris(8-hyd-roxyquinolinato)aluminium(III). Using these composites, electrochemical reduction of nitrite to ammonia with a faradaic efficiency of 61% was reported.

  • 4. Acharya, Shravan
    et al.
    Winther-Jensen, Bjorn
    Spiccia, Leone
    Ohlin, André C.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rates of water exchange in 2,2'-bipyridine and 1,10-phenanthroline complexes of CoII and MnII2017In: Australian journal of chemistry (Print), ISSN 0004-9425, E-ISSN 1445-0038, Vol. 70, no 6, 751-754 p.Article in journal (Refereed)
    Abstract [en]

    The rates and activation parameters of water exchange at pH 3.0 have been determined using variable temperature 17O NMR spectroscopy for four CoII complexes and one MnII complex: [Co(bpy)(H2O)4]2+, [Co(bpy)2 (H2O)2]2+, [Co(phen)-(H2O)4]2+, [Co(phen)2 (H2O)2]2+, and [Mn(bpy)(H2O)4]2+ (bpy = 2,2′-bipyridyl and phen = 1,10-phenanthroline). Substitution of aquo ligands with 1,10-phenanthroline or 2,2′-bipyridyl leads to an increase in the rate of exchange in the manganese complexes, from k298 (1.8 ± 0.1) × 107 s-1 for [Mn(H2O)6]2+ to (7.2 ± 0.3) × 107 s-1 for [Mn(phen)2 (H2O)2]2+, whereas the trends are more complex for the cobalt complexes. We have used the new data in conjunction with literature data for similar complexes to analyse the effect of M–OH2 distance and degree of substitution.

  • 5.
    Achtel, Christian
    et al.
    Friedrich Schiller University of Jena.
    Heinze, Thomas
    Friedrich Schiller University of Jena.
    Homogenous modification of cellulose in the new solvent triethyloctylammonium chloride in combination with organic liquids2016In: The 7th Worskshop on Cellulose, Regenerated Cellulose and Cellulose Derivatives, 2016Conference paper (Other academic)
    Abstract [en]

    Recently, it has been demonstrated that triethyloctylammonium chloride (N2228Cl) bears great properties as cellulose solvent both as melt and in combination with organic solvents (Kostag et al. 2013; Kostag et al. 2014). On one hand, N2228Cl and N,N-dimethylacetamide (DMAc) dissolve cellulose within 2 h without prior activation of the polysaccharide. On the other, N2228Cl unexpectedly dissolves cellulose in the presence of acetone, which typically is known as precipitation agent for cellulose. On very recent studies, the novel solvent was applied for tosylation, acetylation and silylation of cellulose (Achtel 2016). These types of reactions were chosen, because tosylcellulose is an important intermediate for nucleophilic displacement reaction with cellulose, cellulose acetates are of industrial interest, and silylation of cellulose is commonly used to achieve products that form ultrathin films by spin-coating useful as model surface. The reactions were studied under different conditions and the resulted degree of substitutions (DS) were compared with values obtained in common cellulose solvents (LiCl/DMAc, DMSO/TBAF or ionic liquids).

  • 6.
    Addario, Barbara
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Huang, Shenghua
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sauer, Uwe
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Backman, Lars
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Crystallization and preliminary X-ray analysis of the Entamoeba histolytica α-actinin-2 rod domain2011In: Acta Crystallographica. Section F: Structural Biology and Crystallization Communications, ISSN 1744-3091, E-ISSN 1744-3091, Vol. 67, no 10, 1214-1217 p.Article in journal (Refereed)
    Abstract [en]

    -Actinins form antiparallel homodimers that are able to cross-link actin filaments. The protein contains three domains: an N-terminal actin-binding domain followed by a central rod domain and a calmodulin-like EF-hand domain at the C-terminus. Here, crystallization of the rod domain of Entamoeba histolytica -actinin-2 is reported; it crystallized in space group P212121, with unit-cell parameters a = 47.8, b = 79.1, c = 141.8 Å. A Matthews coefficient VM of 2.6 Å3 Da-1 suggests that there are two molecules and 52.5% solvent content in the asymmetric unit. A complete native data set extending to a d-spacing of 2.8 Å was collected on beamline I911-2 at MAX-lab, Sweden.

     

  • 7. Adnan, Muhammad
    et al.
    Iqbal, Javed
    Bibi, Shamsa
    Hussain, Riaz
    Akhtar, Muhammad Nadeem
    Rashid, Muhammad Abid
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ayub, Khurshid
    Fine Tuning the Optoelectronic Properties of Triphenylamine Based Donor Molecules for Organic Solar Cells2017In: Zeitschrift fur physikalische Chemie (Munchen. 1991), ISSN 0942-9352, Vol. 231, no 6, 1127-1139 p.Article in journal (Refereed)
    Abstract [en]

    Geometrical parameters, electronic structures and photophysical properties of three new triphenylamine (TPA) and diphenylamine (DPA) based electron donor materials M1-M3 (for organic solar cells) have been investigated through density functional theory (DFT) methods at the B3LYP/6-31G(d) level of the theory. TPA and DPA are used as donor moieties due to their electron donating ability while benzothiazole, cyanide and cyanomethylacetate (CMA) moieties have been taken as acceptor moieties. The time dependent-DFT (TD-DFT) method has been employed [TD-B3LYP/6-31G (d)] for the computation of excited state properties in the gas phase and in solvent (chloroform). The polarization continuum model is applied for calculations in the solvent phase. The designed molecules exhibited broad absorption in the visible and near infra-red region of spectrum with respect to a reference molecule "R" of a similar class of compounds. Based on reorganization energies calculations, these materials could act as excellent hole transport materials.

  • 8. Aeppli, Christoph
    et al.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Holmstrand, Henry
    Gustafsson, Örjan
    Use of Cl and C Isotopic Fractionation to Identify Degradation and Sources of Polychlorinated Phenols: Mechanistic Study and Field Application2013In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, no 2, 790-797 p.Article in journal (Refereed)
    Abstract [en]

    The widespread use of chlorinated phenols (CPs) as a wood preservative has led to numerous contaminated sawmill sites. However, it remains challenging to assess the extent of in situ degradation of CPs. We evaluated the use of compound-specific chlorine and carbon isotope analysis (Cl- and C-CSIA) to assess CP biotransformation. In a laboratory system, we measured isotopic fractionation during oxidative 2,4,6-trichlorophenol dechlorination by representative soil enzymes (C. fumago chloroperoxidase, horseradish peroxidase, and laccase from T. versicolor). Using a mathematical model, the validity of the Rayleigh approach to evaluate apparent kinetic isotope effects (AKIE) was confirmed. A small but significant Cl-AKIE of 1.0022 ± 0.0006 was observed for all three enzymes, consistent with a reaction pathway via a cationic radical species. For carbon, a slight inverse isotope effect was observed (C-AKIE = 0.9945 ± 0.0019). This fractionation behavior is clearly distinguishable from reported reductive dechlorination mechanisms. Based on these results we then assessed degradation and apportioned different types of technical CP mixtures used at two former sawmill sites. To our knowledge, this is the first study that makes use of two-element CSIA to study sources and transformation of CPs in the environment.

  • 9.
    Afvander, Åsa
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Development of a working method for the study of a distillation process: Distillation of a multicomponent system2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 10.
    Aglar, Öznur
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Design and synthesis of inhibitors of the ADP ribosylating toxin ExoS: Targeting the Type III Secretion System (T3SS) of Pseudomonas aeruginosa.2016Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
  • 11.
    Agnemo, Roland
    Umeå University, Faculty of Science and Technology.
    Ligniners reaktioner med alkalisk väteperoxid1981Doctoral thesis, monograph (Other academic)
    Abstract [en]

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

  • 12. Agrawal, Ganesh Kumar
    et al.
    Job, Dominique
    Kieselbach, Thomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Barkla, Bronwyn J.
    Chen, Sixue
    Deswal, Renu
    Luethje, Sabine
    Amalraj, Ramesh Sundar
    Tanou, Georgia
    Ndimba, Bongani Kaiser
    Cramer, Rainer
    Weckwerth, Wolfram
    Wienkoop, Stefanie
    Dunn, Michael J.
    Kim, Sun Tae
    Fukao, Yochiro
    Yonekura, Masami
    Zolla, Lello
    Rohila, Jai Singh
    Waditee-Sirisattha, Rungaroon
    Masi, Antonio
    Wang, Tai
    Sarkar, Abhijit
    Agrawal, Raj
    Renaut, Jenny
    Rakwal, Randeep
    INPPO Actions and Recognition as a Driving Force for Progress in Plant Proteomics: Change of Guard, INPPO Update, and Upcoming Activities2013In: Proteomics, ISSN 1615-9853, E-ISSN 1615-9861, Vol. 13, no 21, 3093-3100 p.Article in journal (Other academic)
    Abstract [en]

    The International Plant Proteomics Organization (INPPO) is a non-profit organization whose members are scientists involved or interested in plant proteomics. Since the publication of the first INPPO highlights in 2012, continued progress on many of the organization's mandates/goals has been achieved. Two major events are emphasized in this second INPPO highlights. First, the change of guard at the top, passing of the baton from Dominique Job, INPPO founding President to Ganesh Kumar Agrawal as the incoming President. Ganesh K. Agrawal, along with Dominique Job and Randeep Rakwal initiated the INPPO. Second, the most recent INPPO achievements and future targets, mainly the organization of first the INPPO World Congress in 2014, tentatively planned for Hamburg (Germany), are mentioned.

  • 13.
    Aguilar, Ximena
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Weise, Christoph
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sparrman, Tobias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wittung-Stafshede, Pernilla
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Macromolecular crowding extended to a heptameric system: the co-chaperonin protein 102011In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 50, no 14, 3034-3044 p.Article in journal (Refereed)
    Abstract [en]

    Experiments on monomeric proteins have shown that macromolecular crowding can stabilize toward heat perturbation and also modulate native-state structure. To assess the effects of macromolecular crowding on unfolding of an oligomeric protein, we here tested the effects of the synthetic crowding agent Ficoll 70 on human cpn10 (GroES in E. coli), a heptameric protein consisting of seven identical β-barrel subunits assembling into a ring. Using far-UV circular dichroism (CD), tyrosine fluorescence, nuclear magnetic resonance (NMR), and cross-linking experiments, we investigated thermal and chemical stability, as well as the heptamer-monomer dissociation constant, without and with crowding agent. We find that crowding shifts the heptamer-monomer equilibrium constant in the direction of the heptamer. The cpn10 heptamer is both thermally and thermodynamically stabilized in 300 mg/mL Ficoll 70 as compared to regular buffer conditions. Kinetic unfolding experiments show that the increased stability in crowded conditions, in part, is explained by slower unfolding rates. A thermodynamic cycle reveals that in presence of 300 mg/mL Ficoll the thermodynamic stability of each cpn10 monomer increases by over 30%, whereas the interfaces are stabilized by less than 10%. We also introduce a new approach to analyze the spectroscopic data that makes use of multiple wavelengths: this provides robust error estimates of thermodynamic parameters.

  • 14. Ahlgren, Joakim
    et al.
    De Brabandere, Heidi
    Reitzel, Kasper
    Rydin, Emil
    Gogoll, Adolf
    Waldeback, Monica
    Sediment phosphorus extractants for phosphorus-31 nuclear magnetic resonance analysis: A quantitative evaluation2007In: Journal of Environmental Quality, ISSN 0047-2425, E-ISSN 1537-2537, Vol. 36, no 3, 892-898 p.Article in journal (Refereed)
    Abstract [en]

    The influence of pre-extractant, extractant, and post-extractant on total extracted amounts of P and organic P compound groups measured with 31 P nuclear magnetic resonance (P-31-NMR) in lacustrine sediment was examined. The main extractants investigated were sodium hydroxide (NaOH) and sodium hydroxide ethylenediaminetetraacetic acid (NaOH-EDTA) with bicarbonate buffered dithionite (BD) or EDTA as pre-extractants. Post extractions were conducted using either NaOH or NaOH-EDTA, depending on the main extractant. Results showed that the most efficient combination of extractants for total P yield was NaOH with EDTA as pre-extractant, yielding almost 50% more than the second best procedure. The P compound groups varying the most between the different extraction procedures were polyphosphates and pyrophosphates. NaOH with BD as pre-extractant was the most efficient combination for these compound groups.

  • 15.
    Ahlgren, Ulf
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Imaging shows insulin-producing cells in diabetes2013In: TrAC. Trends in analytical chemistry, ISSN 0165-9936, Vol. 44, III-III p.Article in journal (Other (popular science, discussion, etc.))
  • 16.
    Ahlkvist, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Formic and Levulinic Acid from Cellulose via Heterogeneous Catalysis2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The chemical industry of today is under increased pressure to develop novel green materials, bio-fuels as well as sustainable chemicals for the chemical industry. Indeed, the endeavour is to move towards more eco-friendly cost efficient production processes and technologies and chemical transformation of renewables has a central role considering the future sustainable supply of chemicals and energy needed for societies. In the Nordic countries, the importance of pulping and paper industry has been particularly pronounced and the declining European demand on these products as a result of our digitalizing world has forced the industry to look at alternative sources of revenue and profitability. In this thesis, the production of levulinic and formic acid from biomass and macromolecules has been studied. Further, the optimum reaction conditions as well as the influence of the catalyst and biomass type were also discussed.

    Nordic sulphite and sulphate (Kraft) cellulose originating from two Nordic pulp mills were used as raw materials in the catalytic synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice used in this study was a macro-porous, cationic ion-exchange resin, Amberlyst 70, for which the optimal reaction conditions leading to best yields were determined. Cellulose from Nordic pulp mills were used as raw materials in the catalytic one-pot synthesis of ‘green’ levulinic and formic acid. The kinetic experiments were performed in a temperature range of 150–200 °C and an initial substrate concentration regime ranging from 0.7 to 6.0 wt %. It was concluded that the most important parameters in the one-pot hydrolysis of biomass were the reaction temperature, initial reactant concentration, acid type as well as the raw material applied. The reaction route includes dehydration of glucose to hydroxymethylfurfural as well as its further rehydration to formic and levulinic acids. The theoretical maximum yield can hardly be obtained due to formation of humins. For this system, maximum yields of 59 mol % and 68 mol % were obtained for formic and levulinic acid, respectively. The maximum yields were separately obtained in a straight-forward conversion system only containing cellulose, water and the heterogeneous catalyst. These yields were achieved at a reaction temperature of 180 °C and an initial cellulose intake of 0.7 wt % and belong to the upper range for solid catalysts so far presented in the literature.

    The reaction network of the various chemical species involved was investigated and a simple mechanistic approach involving first order reaction kinetics was developed. The concept introduces a one-pot procedure providing a feasible route to green platform chemicals obtained via conversion of coniferous soft wood pulp to levulinic and formic acids, respectively. The model was able to describe the behaviour of the system in a satisfactory manner (degree of explanation 97.8 %). Since the solid catalyst proved to exhibit good mechanical strength under the experimental conditions applied here and a one-pot procedure providing a route to green platform chemicals was developed. A simplified reaction network of the various chemical species involved was investigated and a mechanistic approach involving first order reaction kinetics was developed.

  • 17.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ajaikumar, Samikannu
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    One-pot catalytic conversion of Nordic pulp media into green platform chemicals2013In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 454, 21-29 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, both sulphite and sulphate (Kraft) cellulose from Nordic pulp mills were used as raw materials in the catalytic one-pot synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice was a macro-porous, cationic ion-exchange resin, Amberlyst 70. The optimal reaction conditions were determined and the influence of various gas atmospheres was investigated. The maximum yields of 53% formic acid and 57% of levulinic acid were separately obtained in a straight-forward conversion system only containing cellulose, water and the heterogeneous catalyst. The concept introduces a one-pot procedure providing a feasible route to green platform chemicals obtained via conversion of coniferous soft wood pulp to levulinic and formic acids, respectively.

  • 18.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mäki-Arvela, Päivi
    Åbo Akademi.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Åbo Akademi University, Process Chemistry Centre, Åbo Akademi University, Industrial Chemistry & Reaction Engineering., Finland.
    Macro-molecules as a source of levulinic acid2014In: International Review of Chemical Engineering, ISSN 2035-1755, Vol. 16, no 1, 44-58 p.Article in journal (Refereed)
    Abstract [en]

    The production of levulinic acid from biomass and macromolecules has been reviewed. It was concluded that the most important parameters in the one-pot hydrolysis of biomass, also including dehydration of glucose to hydroxymethylfurfural as well as its further rehydration to formic and levulinic acids, respectively, are the reaction temperature, initial reactant concentration, acid type as well as the raw material applied. The theoretical maximum yield can hardly be obtained due to formation of humins. Further, the optimum reaction conditions as well as the influence of the catalyst and biomass type are also discussed.

  • 19.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wärnå, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Salmi, Tapio
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Reaction Network upon One-pot Catalytic Conversion of Pulp2013In: / [ed] Sauro Pierucci, Jiří J. Klemeš, AIDIC - associazione italiana di ingegneria chimica, 2013, Vol. 32, 649-654 p.Conference paper (Refereed)
    Abstract [en]

    Nordic sulphite and sulphate (Kraft) cellulose originating from Nordic pulp mills were used as raw materials in the catalytic synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice used in this study was a macro-porous, cationic ion-exchange resin Amberlyst 70 for which the optimal reaction conditions leading to best yields were determined. For this system, maximum yields of 53 mol-% and 57 mol-% were obtained for formic and levulinic acid, respectively. The reaction network of the various chemical species involved was investigated and a simple mechanistic approach involving first order reaction kinetics was developed. The prototype model was able to describe the behaviour of the system in a satisfactory manner.

  • 20.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Catalytic conversion of lignocellulosic materials2010Conference paper (Other academic)
  • 21.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wärnå, Johan
    Åbo Akademi.
    Salmi, Tapio
    Åbo Akademi.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Experimental and Kinetic Modelling Studies upon Conversion of Nordic Pulp into Levulinic AcidManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, sulphite cellulose from a Swedish pulp mill was applied as the raw material upon catalytic, one-pot synthesis of green platform chemicals – levulinic and formic acids. Cationic ion-exchange resin, Amberlyst 70, was the catalyst of choice and the optimal reaction conditions leading to best yields were determined. The kinetic experiments were performed in a temperature range of 180–200 °C and an initial substrate concentration regime ranging from 0.7 to 6.0 wt %. For this system, maximum theoretical yields of around 59 mol % and 68 mol % were obtained for formic and levulinic acid, respectively. These yields were achieved at a reaction temperature of 180 °C and an initial cellulose intake of 0.7 wt %. A simplified reaction network of the various chemical species involved was investigated and a mechanistic approach involving first order reaction kinetics was developed. The model was able to describe the behaviour of the system in a satisfactory manner (degree of explanation 97.8 %). Since the solid catalyst proved to exhibit good mechanical strength under the experimental conditions applied here, the concept introduces a one-pot procedure providing a route to green platform chemicals from coniferous soft wood pulp to produce levulinic and formic acids, respectively.

  • 22.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wärnå, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University,Turku, Finland.
    Salmi, Tapio
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University,Turku, Finland.
    Heterogeneously catalyzed conversion of nordic pulp to levulinic and formic acids2016In: Reaction Kinetics, Mechanisms and Catalysis, ISSN 1878-5190, E-ISSN 1878-5204, Vol. 119, no 2, 415-427 p.Article in journal (Refereed)
    Abstract [en]

    Herein, one-pot conversion of cellulose to platform chemicals, formic and levulinic acids was demonstrated. The catalyst selected was an affordable, acidic ion-exchange resin, Amberlyst 70, whereas the cellulose used was sulfite cellulose delivered by a Swedish pulp mill. Furthermore, in an attempt to better understand the complex hydrolysis network of the polysaccharide, kinetic experiments were carried out to pinpoint the optimal reaction conditions with an initial substrate concentration of 0.7–6.0 wt% and a temperature range of 180–200 °C. Higher temperatures could not be used due to the limitations in the thermal stability of the catalyst. Overall, maximum theoretical yields of 59 and 68 mol% were obtained for formic and levulinic acid, respectively. The parameters allowing for the best performance were reaction temperature of 180 °C and initial cellulose concentration of 0.7 wt%. After studying the behavior of the system, a simplified reaction network in line with a mechanistic approach was developed and found to follow first order reaction kinetics. A satisfactory fit of the model to the experimental data was achieved (97.8 % degree of explanation). The catalyst chosen exhibited good mechanical strength under the experimental conditions and thus, a route providing green platform chemicals from soft wood pulp from coniferous trees (mixture of Scots Pine and Norway Spruce) was demonstrated.

  • 23. Aid, T.
    et al.
    Hyvarinen, S.
    Vaher, M.
    Koel, M.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Saccharification of lignocellulosic biomasses via ionic liquid pretreatment2016In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 92, 336-341 p.Article in journal (Refereed)
    Abstract [en]

    The current work focuses on the pretreatment efficiency of ILs combined with heat for woody biomass consisting of spruce, birch and pine as well as winter wheat straw. The latter was investigated as a comparison and with the aim to enhance its digestibility during enzymatic hydrolysis whereby the influence of IL-treatment to cellulose resistance for hydrolysis was investigated. Considering the wood species, the most common and industrially important wood species in Northern Europe were chosen in the present work and the goal was to obtain fermentable sugars and their degradation product, i.e. 5-hydroxymethylfurfural (5-HMF), which is known valuable platform chemical. Further, the differences in the yields of IL-obtainable carbohydrates between these species were studied. The highest sugar yields were obtained to glucose in the case of spruce and arabinose in the case of pine sapwood, 12.07 and 7.72 mmol/L, respectively. The highest 5-HMF yield was obtained for spruce heartwood (9.18 mmol/L) with longer treatment time, such as 100h. However, regarding woody biomass, the present work was focused more on the study and analysis of the IL-containing liquid part, wood hydrolysate, after IL-treatment aiming to answer the analysis challenges related to this fraction.

  • 24.
    Aigner, Harald
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Characterization of FtsH proteases in the annual plant Arabidopsis thaliana2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background FtsH is an ATP-dependent membrane-bound metalloprotease. A. thaliana contains 12 FtsH proteases localized in membranes of chloroplasts and mitochondria where they form homo- or hetero-hexameric complexes. FtsH11 – the main subject of this thesis – is located in the chloroplast envelope.

     

    Methods

    • Field studies with A. thaliana to determine Darwinian fitness. A growth under outdoor conditions often allows discovering of phenotypes that are unascertainable in the controlled environment of growth chambers.
    • Proteomic methods to discover fragments of substrate proteins (limited proteolysis) and changes in the proteome of FtsH protease deficient mutants.

     

    Results ftsh11 has increased amount of: RuBisCO activase, several Calvin cycle enzymes, two enzymes involved in starch synthesis and some chaperons. Some of those enzymes have been identified as possible substrates of FtsH11. Under long photoperiods ftsh11 develops a chlorotic phenotype accompanied by decreasing NADP+/NADPH ratio and increase of ROS damaged proteins. 

  • 25.
    Aigner, Harald
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comparison of hypothetical 3D-structures of Arabidopsis thaliana FtsH Proteases with the aim to predict FtsH complex formationManuscript (preprint) (Other academic)
    Abstract [en]

    In Arabidopsis thaliana 12 metallo proteases of the FtsH family are located in the organellar membranes of chloroplasts and mitochondria. While it is known for the Arabidopsis FtsH proteases FtsH1, 2, 5 and 8 to form a hetero–oligomeric, hexameric complex in the chloroplast thylakoid membrane and for FtsH3 and 10 in the inner membrane of mitochondria, no data are available for the remaining (low abundant) FtsH proteases . We compared the sequence identity of amino acids predicted to be relevant in complex formation of FtsH proteases in order to predict additional hetero-oligomeric FtsH complexes. Focus was set on FtsH11 and FtsH4, two subunits that might form a complex in mitochondria. 

  • 26.
    Aigner, Harald
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Searching for substrates of the metallo protease FtsH11 of Arabidopsis thaliana using N-terminal proteomics2012Manuscript (preprint) (Other academic)
    Abstract [en]

    FtsH11 is a membrane-bound metalloprotease localized in mitochondria and in the chloroplast envelope of Arabidopsis thaliana. An ftsh11 knock-out mutant has been shown to develop a chlorotic phenotype in prolonged photoperiods. The proteome of the ftsh11 chloroplast revealed increased abundance of several Calvin cycle enzymes, chaperones and some other proteins, however, none of those proteins could be verified to be an FtsH11 substrate (Harald Aigner, Raik Wagner, Lars L.E. Sjögren, Holger Eubel, A. Harvey Millar, Adrian K. Clarke, Christiane Funk, 2012, manuscript submitted). Here, we have used positional proteomics to identify peptides that report FtsH11 processing events. In this work we were able to identify seven chloroplast-localized proteins that are processed in wild type, but not in ftsh11.  

  • 27.
    Ajaikumar, Samikannu
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ahlkvist, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kordas, K
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Piispankatu 8, FIN-20500, Turku/Åbo, Finland.
    Oxidation of α-pinene over gold containing bimetallic nanoparticles supported on reducible TiO2 by DPU method2011In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 392, no 1-2, 11-18 p.Article in journal (Refereed)
    Abstract [en]

    A series of bimetallic catalysts Au–M (where M = Cu, Co and Ru) were supported on a reducible TiO2 oxide via deposition-precipitation (DP) method with a slow decomposition of urea as the precipitating agent. The characteristic structural features of the prepared materials were characterized by various physico-chemical techniques such as X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). XPS results indicated the formation of alloyed bimetallic particles on the TiO2 support. TEM results confirmed the fine dispersion of metal nanoparticles on the support with an average particle size in the range of 3–5 nm. An industrially important process, oxy-functionalization of α-pinene was carried out over the prepared bimetallic heterogeneous catalysts under liquid phase conditions. Reaction parameters such as the reaction time, temperature, and the effect of solvent were studied for optimal conversion of α-pinene into verbenone. The major products obtained were verbenone, verbenol, α-pinene oxide and alkyl-pinene peroxide. The activity of the catalysts followed the order; AuCu/TiO2 > AuCo/TiO2 > Cu/TiO2 > Au/TiO2 > AuRu/TiO2. Upon comparison of the various catalysts, AuCu/TiO2 was found to be an active and selective catalyst towards the formation of verbenone. The temperature, nature of the catalysts and the choice of solvents greatly influenced the reaction rate.

  • 28.
    Ajaikumar, Samikannu
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Backiaraj, Muthaiah
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pandurangan, Arumugam
    Transesterification of diethyl malonate with n-butanol over HPWA/MCM-41 molecular sieves2013In: Journal of porous materials, ISSN 1380-2224, E-ISSN 1573-4854, Vol. 20, no 4, 951-959 p.Article in journal (Refereed)
    Abstract [en]

    Mesoporous Si-MCM-41 and Al-MCM-41 (Si/Al = 100) materials were synthesized via a hydrothermal method. Three different ratios (10, 20 and 30 wt%) of heteropoly tungstic acid (HPWA) was loaded on Si-MCM-41 by wet impregnation techniques. The characteristic structural features of the prepared materials were studied by various physico-chemical techniques such as X-ray diffraction (XRD), Nitrogen physisorption (BET), temperature programmed desorption of ammonia (TPD) and transmission electron microscopy (TEM). Transesterification of diethyl malonate (DEM) with n-butanol under autogeneous conditions in a temperature range from 50 to 125 °C was selected as the test reaction for the as synthesized materials. The reactants were fed with various mole ratios in order to determine the optimal feed composition leading to maximum yields of transesterified products. The results indicated that the conversion of diethylmalonate depends on the HPWA concentration on the support, temperature, reaction time and mole ratio of the reactants. Further, the catalytic efficiency of HPWA/MCM-41 was compared with that of Al-MCM-41. The solid acid HPWA/MCM-41 catalysts have several advantages in comparison to conventional mineral acid catalysts which are heterogeneous, eco-friendly, highly active and selective in the formation of transesters.

  • 29.
    Al Mamoon, Hassan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Evaluation of the separation capacity of different GC columns for tetra- to octachlorinated PCDD/Fs2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 30.
    Alam, Md Khorshed
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Fabrication of surface enhanced Raman spectroscopy (SERS) active substrates based on vertically aligned nitrogen doped carbon nanotube forest2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work describes the fabrication and surface enhanced Raman spectroscopy (SERS) characterization of vertically aligned nitrogen (N) doped multi walled carbon nanotube (MWCNT) forests coated by silver (Ag) and gold (Au) nanoparticles. In the present work, the CNT forests were grown from a catalyst metal layer by the chemical vapor deposition (CVD) process at temperature of 800 oC and a physical vapor deposition (PVD) and annealing processes were applied subsequently for the evaporation and diffusion of noble metal nanoparticles on the forest.

    Transistor patterning of 20, 50 and 100 μm were made onto the silicon-oxide (SiO2) wafers through the photolithography process with and without depositing a thickness of 10 nm titanium (Ti) buffer layer on the Si-surfaces. Iron (Fe) and cobalt (Co) were used together to deposite a thickness of 5 nm catalyst layer onto the Single Side Polished (SSP) wafers. As carbon and nitrogen precursor for the CNT growth was used pyridine. Two different treatment times (20 and 60 minutes) in the CVD process determined the CNT forest height. Scanning Electron Microscopy (SEM) imaging was employed to characterize the CNT forest properties and Ag and Au nanoparticle distribution along the CNT walls.

    The existence of “hot spots” created by the Ag and Au nanoparticles through the surface roughness and plasmonic properties was demonstrated by the SERS measurements. Accordingly, the peak intensity at wave number of 1076 cm-1 was picked up from each SERS spectra to establish the Ag- and Au-trend curves with different concentrations of 4-ATP solution. The SERS mapping was also carried out to study the Ag- and Au-coated CNT surface homogeneity and “hot spots” distribution on the CNT surface. The SERS enhancement factors (EF) were calculated by applying an analyte solution of ethanolic 4-ATP on the CNT surface. The calculated values of EF from Ag- and Au-coated CNT forests were 9×106 and 2.7×105 respectively. 

  • 31.
    Albers, Michael F
    et al.
    Department of Chemical Biology, Max Planck Institute for Molecular Physiology.
    Hedberg, Christian
    Amino acid building blocks for Fmoc solid-phase synthesis of peptides phosphocholinated at serine, threonine, and tyrosine2013In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 78, no 6, 2715-2719 p.Article in journal (Refereed)
    Abstract [en]

    Phosphocholination of eukaryotic host cell proteins has recently been identified as a novel post-translational modification important for bacterial pathogenesis. Here, we describe the first straightforward synthetic strategy for peptides containing phosphocholinated serine, threonine, or tyrosine residues using preformed functional amino acid building blocks, fully compatible with standard Fmoc solid-phase peptide synthesis.

  • 32.
    Albers, Michael F
    et al.
    Department of Chemical Biology, Max-Planck Institute of Molecular Physiology.
    van Vliet, Bart
    Hedberg, Christian
    Amino acid building blocks for efficient Fmoc solid-phase synthesis of peptides adenylylated at serine or threonine2011In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 13, no 22, 6014-6017 p.Article in journal (Refereed)
    Abstract [en]

    The first straightforward building block based (non-interassembly) synthesis of peptides containing adenylylated serine and threonine residues is described. Key features include final global acidolytic protective group removal as well as full compatibility with standard Fmoc solid-phase peptide synthesis (SPPS). The described Thr-AMP SPPS-building block has been employed in the synthesis of the Thr-adenylylated sequence of human GTPase CDC42 (Ac-SEYVP-T(AMP)-VFDNYGC-NH(2)). Further, we demonstrate proof-of-concept for the synthesis of an Ser-adenylylated peptide (Ac-GSGA-S(AMP)-AGSGC-NH(2)) from the corresponding adenylylated serine building block.

  • 33.
    Albers, Michael Franz
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis and investigation of bacterial effector molecules2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    During infections, bacterial microorganisms initiate profound interactions with mammalian host cells. Usually defense mechanisms of the host destroy intruding bacteria in rapid manner. However, many bacterial pathogens have evolved in a way to avoid these mechanisms. By use of effector molecules, which can be small organic molecules or proteins with enzymatic activity, the host is manipulated on a molecular level. Effectors mediating post-translational modifications (PTMs) are employed by many pathogens to influence the biological activity of host proteins. In the presented thesis, two related PTMs are investigated in detail: Adenylylation, the covalent transfer of an adenosine monophosphate group from adenosine triphosphate onto proteins, and phosphocholination, the covalent transfer of a phosphocholine moiety onto proteins. Over the past years, enzymes mediating these modifications have been discovered in several pathogens, especially as a mechanism to influence the signaling of eukaryotic cells by adenylylating or phosphocholinating small GTPases. However, the development of reliable methods for the isolation and identification of adenylylated and phosphocholinated proteins remains a vehement challenge in this field of research. This thesis presents general procedures for the synthesis of peptides carrying adenylylated or phosphocholinated tyrosine, threonine and serine residues. From the resulting peptides, mono-selective polyclonal antibodies against adenylylated tyrosine and threonine have been raised. The antibodies were used as tools for proteomic research to isolate unknown substrates of adenylyl transferases from eukaryotic cells. Mass spectrometric fragmentation techniques have been investigated to ease the identification of adenylylated proteins. Furthermore, this work presents a new strategy to identify adenylylated proteins. Additionally, small effector molecules are involved in the regulation of infection mechanisms. In this work, the small molecule LAI-1 (Legionella autoinducer 1) from the pathogen Legionella pneumophila, the causative agent of the Legionnaire’s disease, was synthesised together with its amino-derivatives. LAI-1 showed are a clear pharmacological effect on the regulation of the life cycle of L. pneumophila, initiating transmissive traits like motility and virulence. Furthermore, LAI-1 was shown to have an effect on eukaryotic cells as well. Directed motility of the eukaryotic cells was significantly reduced and the cytoskeletal architecture was reorganised, probably by interfering with the small GTPase Cdc42.

  • 34.
    Albán Reyes, Diana Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Karlsson, Leif
    AkzoNobel.
    de Wit, Paul
    AkzoNobel.
    Svedberg, Anna
    MoRe Research.
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Activation of dissolving celluloses pulp for viscose and cellulose ether production2016Conference paper (Other academic)
    Abstract [en]

    Mercerisation of cellulose by alkali treatment is the most common procedure used to activate natural cellulose fibres into many commercial cellulosic materials. During mercerisation, the NaOH solution enters the cellulose fibres, transforming them into a swollen and a highly reactive material called alkali cellulose (Na-Cell). In case NaOH is completely washed out of the cellulose structure, Na-Cell turns into Cellulose II upon drying.

    Traditionally the cellulose is mercerised by suspending it in a 15-20 % NaOH solution. The result is a high (15-25 mol/mol) NaOH: Anhydroglucose  molar ratio (r) and mercerisation in these conditions have been extensively studied. However, in modern production of cellulose ethers, the mercerisation conditions are often very different. The main reason is that any excess of water and OH--ions used during the mercerisation can later react with different chemicals in the process, thus forming unwanted by-products e.g. methanol. One way to avoid this kind of side reaction is by using low-water-content mercerisation conditions, i.e. low (r) = 0.8-1.8 mol/mol and high NaOH concentration (45-55% w/w). The traditional mercerisation is a suspension process while the cellulose during the latter process, i.e low-water-content mercerisation conditions, remains quite “dry”. Thus, although the chemical reaction principles of activation of cellulose for both viscose and cellulose ethers processes are the same, the activation conditions used are often very different. Therefore, the different dependencies of process parameters as well as any similarities between the processes are interesting.

    The presentation summarises the findings presented in two papers which described the influence of the different parameters on the mercerisation/activation of softwood Sulphite dissolving pulp in viscose production conditions (Albán Reyes et al. 2016) and cellulose derivatives production conditions (Albán Reyes et al.) respectively. In the individual studies this has been done by analysing the degree of transformation (DoT) of dissolving pulp to Na-cellulose (or more correctly cellulose II after washing and upon drying) as a function of simultaneous variation of [NaOH], temperature, and reaction time varied using design of experiment. Also the (r) was varied for samples mercerised at dry conditions. A combination of Raman imaging and multivariate data analysis have been used to study the DoT to Cellulose II.

    It was found that the mercerisation under the different conditions was dependent on different parameters. For traditional mercerisation, on the one hand, the temperature was shown to be important for the DoT and showed negative correlation with the data, while [NaOH] showed a positive correlation. On the other hand, at low-water-content mercerisation conditions the (r) was overall most important while the temperature showed no statistical importance in a Partial least squares analysis. Traditional mercerisation gave much higher DoT than the low-water-content mercerisation. Thus,  the data for low-water-content mercerisation was further examined at the different (r). The same chemistry is always expected and the different influences of the parameters seen is understood and discussed in terms of the different physical reaction mechanisms.  

  • 35.
    Albán Reyes, Diana Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eriksson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Karlsson, Leif
    AkzoNobel.
    de Wit, Paul
    AkzoNobel.
    Svdberg, Anna
    MoRe Research.
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Activation of dissolving celluloses pulp for viscose and cellulose ether production2016In: The 7th workshop on Cellulose, Regenerated cellulose and cellulose derivatives, 2016Conference paper (Other academic)
    Abstract [en]

    Mercerisation of cellulose by alkali treatment is the most common procedure used to activate natural cellulose fibres into many commercial cellulosic materials. During mercerisation, the NaOH solution enters the cellulose fibres, transforming them into a swollen and a highly reactive material called alkali cellulose (Na-Cell). In case NaOH is completely washed out of the cellulose structure, Na-Cell turns into Cellulose II upon drying.

    Traditionally the cellulose is mercerised by suspending it in a 15-20 % NaOH solution. The result is a high (15-25 mol/mol) NaOH: Anhydroglucose  molar ratio (r) and mercerisation in these conditions have been extensively studied. However, in modern production of cellulose ethers, the mercerisation conditions are often very different. The main reason is that any excess of water and OH--ions used during the mercerisation can later react with different chemicals in the process, thus forming unwanted by-products e.g. methanol. One way to avoid this kind of side reaction is by using low-water-content mercerisation conditions, i.e. low (r) = 0.8-1.8 mol/mol and high NaOH concentration (45-55% w/w). The traditional mercerisation is a suspension process while the cellulose during the latter process, i.e low-water-content mercerisation conditions, remains quite “dry”. Thus, although the chemical reaction principles of activation of cellulose for both viscose and cellulose ethers processes are the same, the activation conditions used are often very different. Therefore, the different dependencies of process parameters as well as any similarities between the processes are interesting.

    The presentation summarises the findings presented in two papers which described the influence of the different parameters on the mercerisation/activation of softwood Sulphite dissolving pulp in viscose production conditions (Albán Reyes et al. 2016) and cellulose derivatives production conditions (Albán Reyes et al.) respectively. In the individual studies this has been done by analysing the degree of transformation (DoT) of dissolving pulp to Na-cellulose (or more correctly cellulose II after washing and upon drying) as a function of simultaneous variation of [NaOH], temperature, and reaction time varied using design of experiment. Also the (r) was varied for samples mercerised at dry conditions. A combination of Raman imaging and multivariate data analysis have been used to study the DoT to Cellulose II.

    It was found that the mercerisation under the different conditions was dependent on different parameters. For traditional mercerisation, on the one hand, the temperature was shown to be important for the DoT and showed negative correlation with the data, while [NaOH] showed a positive correlation. On the other hand, at low-water-content mercerisation conditions the (r) was overall most important while the temperature showed no statistical importance in a Partial least squares analysis. Traditional mercerisation gave much higher DoT than the low-water-content mercerisation. Thus,  the data for low-water-content mercerisation was further examined at the different (r). The same chemistry is always expected and the different influences of the parameters seen is understood and discussed in terms of the different physical reaction mechanisms.  

  • 36.
    Albán Reyes, Diana Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden .
    Svedberg, Anna
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    The influence of different parameters on the mercerisation of cellulose for viscose production2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 2, 1061-1072 p.Article in journal (Refereed)
    Abstract [en]

    A quantitative analysis of degree of transformation from a softwood sulphite dissolving pulp to alkalised material and the yield of this transformation as a function of the simultaneous variation of the NaOH concentration, denoted [NaOH], reaction time and temperature was performed. Samples were analysed with Raman spectroscopy in combination with multivariate data analysis and these results were confirmed by X-ray diffraction. Gravimetry was used to measure the yield. The resulting data were related to the processing conditions in a Partial Least Square regression model, which made it possible to explore the relevance of the three studied variables on the responses. The detailed predictions for the interactive effects of the measured parameters made it possible to determine optimal conditions for both yield and degree of transformation in viscose manufacturing. The yield was positively correlated to the temperature from room temperature up to 45 A degrees C, after which the relation was negative. Temperature was found to be important for the degree of transformation and yield. The time to reach a certain degree of transformation (i.e. mercerisation) depended on both temperature and [NaOH]. At low temperatures and high [NaOH], mercerisation was instantaneous. It was concluded that the size of fibre particles (mesh range 0.25-1 mm) had no influence on degree of transformation in viscose processing conditions, apparently due to the quick reaction with the excess of NaOH.

  • 37.
    Albán Reyes, Diana Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Schröder, Ulf
    AkzoNobel.
    Karlsson, Leif
    AkzoNobel.
    de Wit, Paul
    AkzoNobel.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Activation of dissolving cellulose pulp at low water content2015In: 4th EPNOE International Polysaccharide Conference: Polysaccharides and polysaccharide-based advance materials: from science to industry, 2015Conference paper (Other academic)
    Abstract [en]

    Mercerisation of cellulose by alkali treatment is the first step in modifying natural cellulose fibres into many commercial cellulosic materials. During treatment, the fiber transforms into a reactive and highly swollen material called alkali cellulose (Na-Cell). In case NaOH is washed out of the cellulose structure, Na-Cell turn into Cellulose II upon drying (Langan et al. 2001).

     

    The aim of the present study was to gain a better understanding of the mercerisation of dissolving cellulose pulp at low water content. This has been done by spraying NaOH onto milled cellulose in a kneader, then washing the cellulose to neutrality to stop the reaction. After drying the transformation degree to cellulose II was analysed. The experiments include variation of temperature (30-60°C), reaction time (5 and 25 min), [NaOH] (45-55%), and NaOH:Cellulose molar ratio (0.8- 1.8). A combination of NIR Raman imaging and multivariate data analysis have been used to study the transformation degree.

     

    To the authors’ knowledge, this is the first time the influence of NaOH: Cellulose molar ratio on the mercerisation process has been studied in a single model together with temperature, reaction time and [NaOH]. Our results indicate that increased NaOH: Cellulose molar ratio has a significant positive influence on transformation degree of dissolving cellulose pulp at low water content.

  • 38. Aldea, Steliana
    et al.
    Snåre, Mathias
    Eränen, Kari
    Grenman, Henrik
    Rautio, Anne-Riika
    Kordás, Krisztian
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, 20500 Åbo-Turku, Finland.
    Salmi, Tapio
    Murzin, Dmitry Y.
    Crystallization of Nano-Calcium Carbonate: The Influence of Process Parameters2016In: Chemie Ingenieur Technik, ISSN 0009-286X, E-ISSN 1522-2640, Vol. 88, no 11, 1609-1616 p.Article in journal (Refereed)
    Abstract [en]

    Precipitated calcium carbonate was synthesized by carbonation of calcium hydroxide in the presence and absence of ultrasound (conventional stirring) at atmospheric as well as at elevated pressures and different initial concentrations of Ca(OH)2. Spherical morphology of the formed calcite was favored at high Ca(OH)2 concentrations and low CO2 pressures. The presence of ultrasound did not show any influence on the reaction rate in case of efficient mixing. A small increase of the reaction rate was observed at lower CO2 pressures. Elevated pressures in combination with ultrasound did not lead to notable changes of reaction rate or particle morphology.

  • 39. Alessi, Daniel S.
    et al.
    Lezama-Pacheco, Juan S.
    Stubbs, Joanne E.
    Janousch, Markus
    Bargar, John R.
    Persson, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bernier-Latmani, Rizlan
    The product of microbial uranium reduction includes multiple species with U(IV)-phosphate coordination2014In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 0016-1258, Vol. 131, 115-127 p.Article in journal (Refereed)
    Abstract [en]

    Until recently, the reduction of U(VI) to U(IV) during bioremediation was assumed to produce solely the sparingly soluble mineral uraninite, UO2(s). However, results from several laboratories reveal other species of U(IV) characterized by the absence of an EXAFS U-U pair correlation (referred to here as noncrystalline U(IV)). Because it lacks the crystalline structure of uraninite, this species is likely to be more labile and susceptible to reoxidation. In the case of single species cultures, analyses of U extended X-ray fine structure (EXAFS) spectra have previously suggested U(IV) coordination to carboxyl, phosphoryl or carbonate groups. In spite of this evidence, little is understood about the species that make up noncrystalline U(IV), their structural chemistry and the nature of the U(IV)-ligand interactions. Here, we use infrared spectroscopy (IR), uranium L-III-edge X-ray absorption spectroscopy (XAS), and phosphorus K-edge XAS analyses to constrain the binding environments of phosphate and uranium associated with Shewanella oneidensis MR-1 bacterial cells. Systems tested as a function of pH included: cells under metal-reducing conditions without uranium, cells under reducing conditions that produced primarily uraninite, and cells under reducing conditions that produced primarily biomass-associated noncrystalline U(IV). P X-ray absorption near-edge structure (XANES) results provided clear and direct evidence of U(IV) coordination to phosphate. Infrared (IR) spectroscopy revealed a pronounced perturbation of phosphate functional groups in the presence of uranium. Analysis of these data provides evidence that U(IV) is coordinated to a range of phosphate species, including monomers and polymerized networks. U EXAFS analyses and a chemical extraction measurements support these conclusions. The results of this study provide new insights into the binding mechanisms of biomass-associated U(IV) species which in turn sheds light on the mechanisms of biological U(VI) reduction. (C) 2014 Elsevier Ltd. All rights reserved.

  • 40. Alhayali, Amani
    et al.
    Tavelin, Staffan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
    Velaga, Sitaram
    Dissolution and precipitation behavior of ternary solid dispersions of ezetimibe in biorelevant media2017In: Drug Development and Industrial Pharmacy, ISSN 0363-9045, E-ISSN 1520-5762, Vol. 43, no 1, 79-88 p.Article in journal (Refereed)
    Abstract [en]

    The effects of different formulations and processes on inducing and maintaining the supersaturation of ternary solid dispersions of ezetimibe (EZ) in two biorelevant media fasted-state simulated intestinal fluid (FaSSIF) and fasted-state simulated gastric fluid (FaSSGF) at different temperatures (25 °C and 37 °C) were investigated in this work.

    Ternary solid dispersions of EZ were prepared by adding polymer PVP-K30 and surfactant poloxamer 188 using melt-quenching and spray-drying methods. The resulting solid dispersions were characterized using scanning electron microscopy, differential scanning calorimetry (DSC), modulated DSC, powder X-ray diffraction and Fourier transformation infrared spectroscopy. The dissolution of all the ternary solid dispersions was tested in vitro under non-sink conditions.

    All the prepared solid dispersions were amorphous in nature. In FaSSIF at 25 °C, the melt-quenched (MQ) solid dispersions of EZ were more soluble than the spray-dried (SD) solid dispersions and supersaturation was maintained. However, at 37 °C, rapid and variable precipitation behavior was observed for all the MQ and SD formulations. In FaSSGF, the melting method resulted in better solubility than the spray-drying method at both temperatures.

    Ternary solid dispersions show potential for improving solubility and supersaturation. However, powder dissolution experiments of these solid dispersions of EZ at 25 °C may not predict the supersaturation behavior at physiologically relevant temperatures.

  • 41.
    Allegrini, Elisa
    et al.
    Technical University of Denmark, Department of Environmental Engineering.
    Boldrin, Alessio
    Tech Univ Technical University of Denmark, Department of Environmental Engineering.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lundtorp, Kasper
    Babcock & Wilcox Vølund A/S, Göteborg, Sweden.
    Fruergaard Astrup, Thomas
    Technical University of Denmark, Department of Environmental Engineering.
    Quality and generation rate of solid residues in the boiler of a waste-to-energy plant2014In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 270, 127-136 p.Article in journal (Refereed)
    Abstract [en]

    The Danish waste management system relies significantly on waste-to-energy (WtE) plants. The ash produced at the energy recovery section (boiler ash) is classified as hazardous waste, and is commonly mixed with fly ash and air pollution control residues before disposal. In this study, a detailed characterization of boiler ash from a Danish grate-based mass burn type WtE was performed, to evaluate the potential for improving ash management. Samples were collected at 10 different points along the boiler's convective part, and analysed for grain size distribution, content of inorganic elements, polychlorinated dibenzo-. p-dioxins and dibenzofurans (PCDD and PCDF), and leaching of metals. For all samples, PCDD and PCDF levels were below regulatory limits, while high pH values and leaching of e.g. Cl were critical. No significant differences were found between boiler ash from individual sections of the boiler, in terms of total content and leaching, indicating that separate management of individual ash fractions may not provide significant benefits. 

  • 42. Allgardsson, Anders
    et al.
    Berg, Lotta
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Akfur, Christine
    Hörnberg, Andreas
    Worek, Franz
    Linusson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ekström, Fredrik J.
    Structure of a prereaction complex between the nerve agent sarin, its biological target acetylcholinesterase, and the antidote HI-62016In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 113, no 20, 5514-5519 p.Article in journal (Refereed)
    Abstract [en]

    Organophosphorus nerve agents interfere with cholinergic signaling by covalently binding to the active site of the enzyme acetylcholinesterase (AChE). This inhibition causes an accumulation of the neurotransmitter acetylcholine, potentially leading to overstimulation of the nervous system and death. Current treatments include the use of antidotes that promote the release of functional AChE by an unknown reactivation mechanism. We have used diffusion trap cryocrystallography and density functional theory (DFT) calculations to determine and analyze prereaction conformers of the nerve agent antidote HI-6 in complex with Mus musculus AChE covalently inhibited by the nerve agent sarin. These analyses reveal previously unknown conformations of the system and suggest that the cleavage of the covalent enzyme-sarin bond is preceded by a conformational change in the sarin adduct itself. Together with data from the reactivation kinetics, this alternate conformation suggests a key interaction between Glu202 and the O-isopropyl moiety of sarin. Moreover, solvent kinetic isotope effect experiments using deuterium oxide reveal that the reactivation mechanism features an isotope-sensitive step. These findings provide insights into the reactivation mechanism and provide a starting point for the development of improved antidotes. The work also illustrates how DFT calculations can guide the interpretation, analysis, and validation of crystallographic data for challenging reactive systems with complex conformational dynamics.

  • 43. Almroth, Bethanie M. Carney
    et al.
    Gunnarsson, Lina M.
    Cuklev, Filip
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kristiansson, Erik
    Larsson, D. G. Joakim
    Waterborne beclomethasone dipropionate affects the physiology of fish while its metabolite beclomethasone is not taken up2015In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 511, 37-46 p.Article in journal (Refereed)
    Abstract [en]

    Asthma is commonly treated with inhalable glucocorticosteroids, including beclomethasone dipropionate (BDP). This is a synthetic prodrug which is metabolized to the more active monopropionate (BMP) and free beclomethasone in humans. To evaluate potential effects of residual drugs on fish, we conducted a 14 day flow-through exposure experiment with BDP and beclomethasone using rainbow trout, and analyzed effects on plasma glucose, hepatic glutathione and catalase activity together with water and body concentrations of the BDP, BMP and beclomethasone. We also analyzed hepatic gene expression in BDP-exposed fish by micro-array and quantitative PCR Beclomethasone (up to 0.65 mu g/L) was not taken up in the fish while BDP (0.65 and 0.07 mu g/L) resulted in accumulation of both beclomethasone, BMP and BDP in plasma, reaching levels up to those found in humans during therapy. Accordingly, exposure to 0.65 mu g/L of BDP significantly increased blood glucose as well as oxidized glutathione levels and catalase activity in the liver. Exposure to beclomethasone or the low concentration of BDP had no effect on these endpoints. Both exposure concentrations of BDP resulted in significantly higher transcript abundance of phosphoenolpyruvate carboxykinase involved in gluconeogenesis, and of genes involved in immune responses. As only the rapidly metabolized prodrug was potent in fish, the environmental risks associated with the use of BDP are probably small. However, the observed physiological effects in fish of BDP at plasma concentrations known to affect human physiology provides valuable input to the development of read-across approaches in the identification of pharmaceuticals of environmental concern.

  • 44. Alonso-Mori, R.
    et al.
    Asa, K.
    Bergmann, U.
    Brewster, A. S.
    Chatterjee, R.
    Cooper, J. K.
    Frei, H. M.
    Fuller, F. D.
    Goggins, E.
    Gul, S.
    Fukuzawa, H.
    Iablonskyi, D.
    Ibrahim, M.
    Katayama, T.
    Kroll, T.
    Kumagai, Y.
    McClure, B. A.
    Messinger, Johannes
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Motomura, K.
    Nagaya, K.
    Nishiyama, T.
    Saracini, C.
    Sato, Y.
    Sauter, N. K.
    Sokaras, D.
    Takanashi, T.
    Togashi, T.
    Ueda, K.
    Weare, W. W.
    Weng, T-C
    Yabashi, M.
    Yachandra, V. K.
    Young, I. D.
    Zouni, A.
    Kern, J. F.
    Yano, J.
    Towards characterization of photo-excited electron transfer and catalysis in natural and artificial systems using XFELs2016In: Faraday discussions (Online), ISSN 1359-6640, E-ISSN 1364-5498, Vol. 194, 621-638 p.Article in journal (Refereed)
    Abstract [en]

    The ultra-bright femtosecond X-ray pulses provided by X-ray Free Electron Lasers (XFELs) open capabilities for studying the structure and dynamics of a wide variety of biological and inorganic systems beyond what is possible at synchrotron sources. Although the structure and chemistry at the catalytic sites have been studied intensively in both biological and inorganic systems, a full understanding of the atomic-scale chemistry requires new approaches beyond the steady state X-ray crystallography and X-ray spectroscopy at cryogenic temperatures. Following the dynamic changes in the geometric and electronic structure at ambient conditions, while overcoming X-ray damage to the redox active catalytic center, is key for deriving reaction mechanisms. Such studies become possible by using the intense and ultra-short femtosecond X-ray pulses from an XFEL, where sample is probed before it is damaged. We have developed methodology for simultaneously collecting X-ray diffraction data and X-ray emission spectra, using an energy dispersive spectrometer, at ambient conditions, and used this approach to study the room temperature structure and intermediate states of the photosynthetic water oxidizing metallo-protein, photosystem II. Moreover, we have also used this setup to simultaneously collect the X-ray emission spectra from multiple metals to follow the ultrafast dynamics of light-induced charge transfer between multiple metal sites. A Mn-Ti containing system was studied at an XFEL to demonstrate the efficacy and potential of this method.

  • 45. Alonso-Mori, Roberto
    et al.
    Kern, Jan
    Gildea, Richard J
    Sokaras, Dimosthenis
    Weng, Tsu-Chien
    Lassalle-Kaiser, Benedikt
    Tran, Rosalie
    Hattne, Johan
    Laksmono, Hartawan
    Hellmich, Julia
    Glöckner, Carina
    Echols, Nathaniel
    Sierra, Raymond G
    Schafer, Donald W
    Sellberg, Jonas
    Kenney, Christopher
    Herbst, Ryan
    Pines, Jack
    Hart, Philip
    Herrmann, Sven
    Grosse-Kunstleve, Ralf W
    Latimer, Matthew J
    Fry, Alan R
    Messerschmidt, Marc M
    Miahnahri, Alan
    Seibert, M Marvin
    Zwart, Petrus H
    White, William E
    Adams, Paul D
    Bogan, Michael J
    Boutet, Sébastien
    Williams, Garth J
    Zouni, Athina
    Messinger, Johannes
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Glatzel, Pieter
    Sauter, Nicholas K
    Yachandra, Vittal K
    Yano, Junko
    Bergmann, Uwe
    Energy-dispersive X-ray emission spectroscopy using an X-ray free-electron laser in a shot-by-shot mode2012In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 109, no 47, 19103-19107 p.Article in journal (Refereed)
    Abstract [en]

    The ultrabright femtosecond X-ray pulses provided by X-ray free-electron lasers open capabilities for studying the structure and dynamics of a wide variety of systems beyond what is possible with synchrotron sources. Recently, this "probe-before-destroy" approach has been demonstrated for atomic structure determination by serial X-ray diffraction of microcrystals. There has been the question whether a similar approach can be extended to probe the local electronic structure by X-ray spectroscopy. To address this, we have carried out femtosecond X-ray emission spectroscopy (XES) at the Linac Coherent Light Source using redox-active Mn complexes. XES probes the charge and spin states as well as the ligand environment, critical for understanding the functional role of redox-active metal sites. Kβ(1,3) XES spectra of Mn(II) and Mn(2)(III,IV) complexes at room temperature were collected using a wavelength dispersive spectrometer and femtosecond X-ray pulses with an individual dose of up to >100 MGy. The spectra were found in agreement with undamaged spectra collected at low dose using synchrotron radiation. Our results demonstrate that the intact electronic structure of redox active transition metal compounds in different oxidation states can be characterized with this shot-by-shot method. This opens the door for studying the chemical dynamics of metal catalytic sites by following reactions under functional conditions. The technique can be combined with X-ray diffraction to simultaneously obtain the geometric structure of the overall protein and the local chemistry of active metal sites and is expected to prove valuable for understanding the mechanism of important metalloproteins, such as photosystem II.

  • 46.
    Alvarez, Laura
    et al.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Hernandez, Sara B
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    de Pedro, Miguel A
    Cava, Felipe
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Ultra-Sensitive, High-Resolution Liquid Chromatography Methods for the High-Throughput Quantitative Analysis of Bacterial Cell Wall Chemistry and Structure2016In: Bacterial Cell Wall Homeostasis: Methods and Protocols / [ed] Hee-Jeon Hong, New York: Springer Science+Business Media B.V., 2016, Vol. 1440, 11-27 p.Chapter in book (Refereed)
    Abstract [en]

    High-performance liquid chromatography (HPLC) analysis has been critical for determining the structural and chemical complexity of the cell wall. However this method is very time consuming in terms of sample preparation and chromatographic separation. Here we describe (1) optimized methods for peptidoglycan isolation from both Gram-negative and Gram-positive bacteria that dramatically reduce the sample preparation time, and (2) the application of the fast and highly efficient ultra-performance liquid chromatography (UPLC) technology to muropeptide separation and quantification. The advances in both analytical instrumentation and stationary-phase chemistry have allowed for evolved protocols which cut run time from hours (2-3 h) to minutes (10-20 min), and sample demands by at least one order of magnitude. Furthermore, development of methods based on organic solvents permits in-line mass spectrometry (MS) of the UPLC-resolved muropeptides. Application of these technologies to high-throughput analysis will expedite the better understanding of the cell wall biology.

  • 47. Ames, William
    et al.
    Pantazis, Dimitrios A
    Krewald, Vera
    Cox, Nicholas
    Messinger, Johannes
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lubitz, Wolfgang
    Neese, Frank
    Theoretical Evaluation of Structural Models of the S(2) State in the Oxygen Evolving Complex of Photosystem II: Protonation States and Magnetic Interactions2011In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, no 49, 19743-19757 p.Article in journal (Refereed)
    Abstract [en]

    Protonation states of water ligands and oxo bridges are intimately involved in tuning the electronic structures and oxidation potentials of the oxygen evolving complex (OEC) in Photosystem II, steering the mechanistic pathway, which involves at least five redox state intermediates S(n) (n = 0-4) resulting in the oxidation of water to molecular oxygen. Although protons are practically invisible in protein crystallography, their effects on the electronic structure and magnetic properties of metal active sites can be probed using spectroscopy. With the twin purpose of aiding the interpretation of the complex electron paramagnetic resonance (EPR) spectroscopic data of the OEC and of improving the view of the cluster at the atomic level, a complete set of protonation configurations for the S(2) state of the OEC were investigated, and their distinctive effects on magnetic properties of the cluster were evaluated. The most recent X-ray structure of Photosystem II at 1.9 Å resolution was used and refined to obtain the optimum structure for the Mn(4)O(5)Ca core within the protein pocket. Employing this model, a set of 26 structures was constructed that tested various protonation scenarios of the water ligands and oxo bridges. Our results suggest that one of the two water molecules that are proposed to coordinate the outer Mn ion (Mn(A)) of the cluster is deprotonated in the S(2) state, as this leads to optimal experimental agreement, reproducing the correct ground state spin multiplicity (S = 1/2), spin expectation values, and EXAFS-derived metal-metal distances. Deprotonation of Ca(2+)-bound water molecules is strongly disfavored in the S(2) state, but dissociation of one of the two water ligands appears to be facile. The computed isotropic hyperfine couplings presented here allow distinctions between models to be made and call into question the assumption that the largest coupling is always attributable to Mn(III). The present results impose limits for the total charge and the proton configuration of the OEC in the S(2) state, with implications for the cascade of events in the Kok cycle and for the water splitting mechanism.

  • 48.
    Andersson, Agneta
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Meier, H.E. Markus
    Ripszam, Matyas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Rowe, Owen
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Wikner, Johan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eilola, Kari
    Legrand, Catherine
    Figueroa, Daniela
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Paczkowska, Joanna
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Lindehoff, Elin
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Elmgren, Ragnar
    Projected future climate change and Baltic Sea ecosystem management2015In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, no Suppl 3, S345-S356 p.Article in journal (Refereed)
    Abstract [en]

    Climate change is likely to have large effectson the Baltic Sea ecosystem. Simulations indicate 2–4 Cwarming and 50–80 % decrease in ice cover by 2100.Precipitation may increase *30 % in the north, causingincreased land runoff of allochthonous organic matter(AOM) and organic pollutants and decreased salinity.Coupled physical–biogeochemical models indicate that, inthe south, bottom-water anoxia may spread, reducing codrecruitment and increasing sediment phosphorus release,thus promoting cyanobacterial blooms. In the north,heterotrophic bacteria will be favored by AOM, whilephytoplankton production may be reduced. Extra trophiclevels in the food web may increase energy losses andconsequently reduce fish production. Future managementof the Baltic Sea must consider the effects of climatechange on the ecosystem dynamics and functions, as wellas the effects of anthropogenic nutrient and pollutant load.Monitoring should have a holistic approach, encompassingboth autotrophic (phytoplankton) and heterotrophic (e.g.,bacterial) processes.

  • 49.
    Andersson, Anja
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Method development for the determination of thiols using HPLC with fluorescence detection2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 50.
    Andersson, Axel
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Biomedicinprogrammet.
    Multivariate distance matching – a novel matching strategy for biomarker pattern discovery in clinical metabolomics2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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