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  • 1.
    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).

  • 2.
    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.

  • 3.
    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, p. 21-29Article 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.

  • 4.
    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.  

  • 5.
    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.  

  • 6.
    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.

  • 7. Andrii, Dudnyk
    et al.
    Matthew, Burman
    Ludmyla, Kulyk
    Olena, Rzhepishevska
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    M/XDR‐TB treatment perspective: how to avoid mountains of pills via digital technologies2018In: Respirology (Carlton South. Print), ISSN 1323-7799, E-ISSN 1440-1843, Vol. 23, no 6, p. 636-637Article in journal (Refereed)
  • 8.
    Badea, Silviu-Laurentiu
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Association of hydrophobic organic compounds to organic material in the soil system2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Contaminated soils and sediments have been identified as significant secondary sources of organic contaminants.  Leaching tests may be useful tools to estimate the mobility of contaminants via the water phase and thereby the risk for groundwater and surface water contamination. The influence of soil composition (peat and clay content) on the leachability was investigated in batch leaching experiments for chemically diverse hydrophobic organic compounds (HOCs: PCP, PAHs, HCB, HCHs, PCBs, and TCDD/Fs). The above mentioned compounds were analyzed by both GC-LRMS (gas chromatography coupled with low resolution mass spectrometry (GC-HRMS) and GC-HRMS (gas chromatography coupled with high resolution mass spectrometry). Also the the leachability of eleven selected PCBs from naturally aged soil (Västervik, Sweden) was investigated in relation to the composition and concentration of dissolved organic matter at different pH (2 to 9), using a pH static test with initial acid/base addition. The the composition and of dissolved organic matter (DOM) at different pH values was explored by FTIR spectroscopy. The results were evaluated by orthogonal projections to latent structures (OPLS).

    Generally, for all model compounds studies, the Kd-values showed a variability of 2-3 orders of magnitude depending on the matrix composition. The Kd-values of moderately hydrophobic compounds, (e.g. HCHs, PCP and Phe), were correlated mainly with the organic matter content of soil. For more hydrophobic compounds (e.g.BaA, HCB and PCB 47), the leachability decreased as the proportions of  OM and clay contents increased. The Kd-values of 1,3,6,8-TCDD and 1,3,6,8-TCDF were  positively correlated with peat content but negatively correlated with clay content, while for PCB 153 and PCB 155 the correlations were reversed. The log Kd-values of all target PCBs decreased with increased pH values and the log Kd-values were highly correlated with the concentration of total organic carbon (TOC) in the leachates. The FTIR analysis of DOM showed that the least chlorinated and hydrophobic PCB congeners (i.e. PCB 28) might be associated with the hydrophilic fraction (i.e. carboxylic groups) of DOM. Our study demonstrated how complex interaction between the organic matter, clay components, pH and DOC influences the leachability of HOCs in a compound-specific manner.

  • 9.
    Berg, C. Anders R.
    Umeå University, Faculty of Teacher Education, Mathematics, Technology and Science Education. Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Factors related to observed attitude change toward learning chemistry among university students2005In: Chemistry education, ISSN 1109-4028, E-ISSN 1109-4028, Chemistry Education Research and Practice, Vol. 6, no 1, p. 1-18Article in journal (Refereed)
    Abstract [en]

    To gain insight into factors associated with changes in attitude toward learning chemistry, six students who displayed major attitude changes were identified through a pre- and post-course attitude questionnaire administered to sixty-six first-year university chemistry students. Those with largest attitude changes, both positive and negative, were selected to highlight the contrast between students. The six students were interviewed; descriptions of their one-semester chemistry course experiences were analyzed to identify factors associated with their change in attitude. A positive attitude change was associated with evidence of motivated behaviour, while a negative change was linked to less motivated behaviour. Students addressed similar factors in the educational setting, but students with positive attitude changes exhibited fewer negative views of educational factors, while students with negative attitude changes showed an opposite pattern. Since the same factors, students’ perceived level of teacher empathy for their efforts at chemistry learning, affected both groups, this indicates a possibility for changes in educational setting beneficial to all students.

  • 10.
    Bergius, Lina
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sulfatmätningar i kokeriet2015Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    This work has been performed in the digester at Domsjö Fabriker in order to clarify the concentration of sulphate-ions comparing to different driving-conditions in the process. The reason to this is to understand and be able to avoid conditions in the digester process that means very high concentrations of sulphate-ions. The work is included in the examination of higher education: process operator at Umeå University.At Domsjö Fabriker similar studies have been done in the digester and from that it has been found out that the concentration of sulphate-ions is connected to pH and over time. The purpose is to approve the understanding of the process conditions to avoid extremely high concentration of sulphate-ions. The mission with this work and the measurements included in the work is to put together results that show when the concentration of sulphate-ions is high. The procedure of the study has consisted in taking samples in series of four, frozen the samples and finally analyzing them by titration and pH-measurements.After 22 evaluated trial-series á four samples each from the boilers it was concluded that the concentration of sulphate-ions was the greatest in the end of this process-step. The pH was upper and the concentration of sulphate lower in the first sample. None of the data is abnormal in any way, and they are all connected and relevant to each other. In this experiment it is not possible to state if the concentration of sulphate is affected by the pH or not.

  • 11. Bjarnsholt, T.
    et al.
    Buhlin, K.
    Dufrêne, Y. F.
    Gomelsky, M.
    Moroni, A.
    Ramstedt, Madeleine
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rumbaugh, K. P.
    Schulte, T.
    Sun, L.
    Åkerlund, B.
    Römling, U.
    Biofilm formation – what we can learn from recent developments2018In: Journal of Internal Medicine, ISSN 0954-6820, E-ISSN 1365-2796, Vol. 284, no 4, p. 332-345Article in journal (Refereed)
    Abstract [en]

    Although biofilms have been observed early in the history of microbial research, their impact has only recently been fully recognized. Biofilm infections, which contribute to up to 80% of human microbial infections, are associated with common human disorders, such as diabetes mellitus and poor dental hygiene, but also with medical implants. The associated chronic infections such as wound infections, dental caries and periodontitis significantly enhance morbidity, affect quality of life and can aid development of follow-up diseases such as cancer. Biofilm infections remain challenging to treat and antibiotic monotherapy is often insufficient, although some rediscovered traditional compounds have shown surprising efficiency. Innovative anti-biofilm strategies include application of anti-biofilm small molecules, intrinsic or external stimulation of production of reactive molecules, utilization of materials with antimicrobial properties and dispersion of biofilms by digestion of the extracellular matrix, also in combination with physical biofilm breakdown. Although basic principles of biofilm formation have been deciphered, the molecular understanding of the formation and structural organization of various types of biofilms has just begun to emerge. Basic studies of biofilm physiology have also resulted in an unexpected discovery of cyclic dinucleotide second messengers that are involved in interkingdom crosstalk via specific mammalian receptors. These findings even open up new venues for exploring novel anti-biofilm strategies.

  • 12. Björlenius, Berndt
    et al.
    Ripszám, Mátyás
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lindberg, Richard H.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pharmaceutical residues are widespread in Baltic Sea coastal and offshore waters: Screening for pharmaceuticals and modelling of environmental concentrations of carbamazepine2018In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 633, p. 1496-1509Article in journal (Refereed)
    Abstract [en]

    The consumption of pharmaceuticals worldwide coupled with modest removal efficiencies of sewage treatment plants have resulted in the presence of pharmaceuticals in aquatic systems globally. In this study, we investigated the environmental concentrations of a selection of 93 pharmaceuticals in 43 locations in the Baltic Sea and Skagerrak. The Baltic Sea is vulnerable to anthropogenic activities due to a long turnover time and a sensitive ecosystem in the brackish water. Thirty-nine of 93 pharmaceuticals were detected in at least one sample, with concentrations ranging between 0.01 and 80 ng/L. One of the pharmaceuticals investigated, the anti-epileptic drug carbamazepine, was widespread in coastal and offshore seawaters (present in 37 of 43 samples). In order to predict concentrations of pharmaceuticals in the sub-basins of the Baltic Sea, a mass balance-based grey box model was set up and the persistent, widely used carbamazepine was selected as the model substance. The model was based on hydrological and meteorological sub-basin characteristics, removal data from smaller watersheds and wastewater treatment plants, and statistics relating to population, consumption and excretion rate of carbamazepine in humans. The grey box model predicted average environmental concentrations of carbamazepine in sub-basins with no significant difference from the measured concentrations, amounting to 0.57–3.2 ng/L depending on sub-basin location. In the Baltic Sea, the removal rate of carbamazepine in seawater was estimated to be 6.2 10−9 s−1 based on a calculated half-life time of 3.5 years at 10 °C, which demonstrates the long response time of the environment to measures phasing out persistent or slowly degradable substances such as carbamazepine. Sampling, analysis and grey box modelling were all valuable in describing the presence and removal of carbamazepine in the Baltic Sea.

  • 13. Bouveresse, D. Jouan-Rimbaud
    et al.
    Pinto, Rui Climaco
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Schmidtke, L. M.
    Locquet, N.
    Rutledge, D. N.
    Identification of significant factors by an extension of ANOVA-PCA based on multi-block analysis2011In: Chemometrics and Intelligent Laboratory Systems, ISSN 0169-7439, E-ISSN 1873-3239, Vol. 106, no 2, p. 173-182Article in journal (Refereed)
    Abstract [en]

    A modification of the ANOVA-PCA method, proposed by Harrington et al. to identify significant factors and interactions in an experimental design, is presented in this article. The modified method uses the idea of multiple table analysis, and looks for the common dimensions underlying the different data tables, or data blocks, generated by the "ANOVA-step" of the ANOVA-PCA method, in order to identify the significant factors. In this paper, the "Common Component and Specific Weights Analysis" method is used to analyse the calculated multi-block data set. This new method, called AComDim, was compared to the standard ANOVA-PCA method, by analysing four real data sets. Parameters computed during the AComDim procedure enable the computation of F-values to check whether the variability of each original data block is significantly greater than that of the noise.

  • 14.
    Bozaghian, Marjan
    et al.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology.
    Rebbling, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Larsson, Sylvia H.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology.
    Xiong, Shaojun
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Combustion characteristics of barley straw stored with CaCO3 using olivine and quartz as bed materials in fluidized bed combustion2017Conference paper (Refereed)
  • 15.
    Broman, Karolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education.
    Parchmann, Ilka
    IPN Leibniz Institute for Science and Mathematics Education, University of Kiel, Germany.
    Students' application of chemical concepts when solving chemistry problems in different contexts2014In: Chemistry Education Research and Practice, ISSN 1756-1108, E-ISSN 1756-1108, Vol. 15, no 4, p. 516-529Article in journal (Refereed)
    Abstract [en]

    Context-based learning approaches have been implemented in school science over the last 40 years as a way to enhance students' interest in, as well as learning outcomes from, science. Contexts are used to connect science with the students' lives and to provide a frame in which concepts can be learned and applied on a ‘need-to-know’-principle. While effects on interest are coherently reported as positive, they are more diverse regarding cognitive learning outcomes. Hence, the demand for further research on criteria of context-based problems and problem-solving processes has been stated. In this paper, a study is presented investigating students' application of chemical concepts when solving context-based chemistry problems. Tasks for context-based problem solving have been designed systematically, using different combinations of contexts, topics and chemistry concepts in relation to the syllabus. Empirical data were collected using think-aloud interviews where 20 upper secondary students used their chemical content knowledge to solve the problems. The 15 context-based problems raised challenges within organic chemistry where concepts like electronegativity, polarity and solubility had to be applied. The difficulty to differentiate between intra- and intermolecular bonding emphasised in earlier research has also been apparent in this study. Besides the structural formula, which was an important part for the students when solving the tasks, the contextualisation of the problems was often used in the responses; students related their answers to the personal, societal or professional context in different ways. The paper explores the results and gives implications for context-based teaching, learning and assessment.

  • 16.
    Buckland, Philip I.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab. Umeå University, Faculty of Arts, Humlab.
    SEAD - The Strategic Environmental Archaeology Database Inter-linking Multiproxy Environmental Data with Archaeological Investigations and Ecology2013In: Archaeology in the Digital Era: Papers from the 40th Annual Conference of Computer Applications and Quantitative Methods in Archaeology (CAA), Southampton, 26-29 March 2012 / [ed] Graeme Earl, Tim Sly, Angeliki Chrysanthi, Patricia Murrieta-Flores, Constantinos Papadopoulos, Iza Romanowska & David Wheatley, Amsterdam University Press, 2013, Vol. 1, p. 320-331Conference paper (Refereed)
    Abstract [en]

    The volume of data on past environmental and climate changes, as well as human interactions with these, has long since passed the level where it is manageable outside of large scale database systems. The Strategic Environmental Archaeology Database project aims to not only store and disseminate such data, but also provide tools for querying and analysing them, whilst maintaining a close connection with the archaeological and ecological data that are essential for their comprehensive interpretation. Large scale, geographically and chronologically unrestricted databases provide us with essentially unlimited scope for putting individual sites into a broader context and applying locally collated data to the investigation of earth system level changes. By providing integrated access to data from a variety of proxies, including plant macrofossils, pollen, insects and geochemistry, along with dating evidence, more complex questions can be answered where any single proxy would not be able to provide comprehensive answers.

  • 17.
    Buckland, Philip I
    et al.
    Umeå University, Faculty of Arts, Archaeology and Sami Studies.
    Johan, Olofsson
    Umeå University, Faculty of Arts, Archaeology and Sami Studies.
    Engelmark, Roger
    Umeå University, Faculty of Arts, Archaeology and Sami Studies.
    SEAD: Strategic Environmental Archaeology Database, planning report2006Report (Other academic)
    Abstract [en]

    This document lays out a strategy for the development of SEAD – A Strategic Environmental Archaeology Database, which will facilitate the digitisation and accessibility augmentation of MAL’s existing data from nearly thirty years of work in the fields of archaeology and environmental science. SEAD will also provide a framework for the entry of data from all future research and consultancy work at MAL, and allow guest researchers and external partners to contribute to, and work with the same data. The planned system will be implemented at both local and internet levels, and be designed with an aim towards broadening its scope with external partners in the future. SEAD will be made available online in order to increase the ease of access to environmental archaeology data and encourage an expansion of both the discipline and Sweden’s role in it. This is inline with current EU strategies on enhancing research infrastructure, and providing a greater insight into human-environment interactions for long term planning.

  • 18. Cao, Lin-Ying
    et al.
    Zheng, Ziye
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ren, Xiao-Min
    Andersson, Patrik L.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Guo, Liang-Hong
    Structure-dependent activity of polybrominated diphenyl ethers and their hydroxylated metabolites on estrogen related receptor gamma: in vitro and in silico study2018In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 52, no 15, p. 8894-8902Article in journal (Refereed)
    Abstract [en]

    Estrogen-related receptor gamma (ERR gamma) is an orphan nuclear receptor having functional cross-talk with classical estrogen receptors. Here, we investigated whether ERR gamma is a potential target 8 of polybrominated diphenyl ethers (PBDEs) and their hydroxylated metabolites (OH-PBDEs). By using a fluorescence competitive binding method established in our laboratory, the binding potencies of 30 PBDEs/OH-PBDEs with ERR gamma were determined for the first time. All of the tested OH-PBDEs and some PBDEs bound to ERR gamma with K-d values ranging from 0.13-13.61 mu M. The OH-PBDEs showed much higher binding potency than their parent PBDEs. A quantitative structure-activity relationship (QSAR) model was developed to analyze the chemical binding potencies in relation to their structural and chemical characteristics. The QSAR model indicated that the molecular size, relative ratios of aromatic atoms, and hydrogen bond donors and acceptors were crucial factors for PBDEs/OH-PBDEs binding. By using a reporter gene assay, we found that most of the low-brominated PBDEs/OH-PBDEs exerted agonistic activity toward ERR gamma, while high-brominated PBDEs/OH-PBDEs had no effect on the basal ERR gamma activity. The docking results showed that the low-brominated PBDEs/OH-PBDEs tended to take an agonistic binding mode while the high-brominated ones tended to take an antagonistic binding mode. Overall, our results suggest ERR gamma to be a potential novel target for PBDEs/OH-PBDEs.

  • 19.
    Engdahl, Cecilia
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Knutsson, Sofie
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fredriksson, Sten-Åke
    Linusson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bucht, Göran
    Ekström, Fredrik
    Acetylcholinesterases from the Disease Vectors Aedes aegypti and Anopheles gambiae: Functional Characterization and Comparisons with Vertebrate Orthologues2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 10, article id e0138598Article in journal (Refereed)
    Abstract [en]

    Mosquitoes of the Anopheles (An.) and Aedes (Ae.) genus are principal vectors of human diseases including malaria, dengue and yellow fever. Insecticide-based vector control is an established and important way of preventing transmission of such infections. Currently used insecticides can efficiently control mosquito populations, but there are growing concerns about emerging resistance, off-target toxicity and their ability to alter ecosystems. A potential target for the development of insecticides with reduced off-target toxicity is the cholinergic enzyme acetylcholinesterase (AChE). Herein, we report cloning, baculoviral expression and functional characterization of the wild-type AChE genes (ace-1) from An. gambiae and Ae. aegypti, including a naturally occurring insecticide-resistant (G119S) mutant of An. gambiae. Using enzymatic digestion and liquid chromatography-tandem mass spectrometry we found that the secreted proteins were post-translationally modified. The Michaelis-Menten constants and turnover numbers of the mosquito enzymes were lower than those of the orthologous AChEs from Mus musculus and Homo sapiens. We also found that the G119S substitution reduced the turnover rate of substrates and the potency of selected covalent inhibitors. Furthermore, non-covalent inhibitors were less sensitive to the G119S substitution and differentiate the mosquito enzymes from corresponding vertebrate enzymes. Our findings indicate that it may be possible to develop selective non-covalent inhibitors that effectively target both the wild-type and insecticide resistant mutants of mosquito AChE.

  • 20.
    Espling, Maria
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Copper-transporting proteins and their interactions with platinum-based anticancer substances2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

      Cisplatin (CisPt) is an important drug that is used against various cancers, including testicular, ovarian, lung, head, and neck cancer. However, its effects are limited by cellular resistance. The resistance is believed to be multifactorial, and may be mediated to varying degree by multiple systems in cells, one of the proposed systems being the copper (Cu) transporting system. The Cu-importer Ctr1 has proven importance for cellular sensitivity to CisPt by regulating its influx, while the Golgi-localized Cu-ATP:ases ATP7A/B can putatively mediate CisPt efflux and/or drug sequestration. Atox1 is a small Cu-chaperone that normally transfers Cu between Ctr1 and ATP7A/B, prior to delivery of Cu to the proteins in the secretory pathway. Since Ctr1 and ATP7A/B are reportedly involved in CisPt-resistance, CisPt interaction with Atox1 was the focus of the project this thesis is based upon.

      Using a variety of techniques, Atox1 was found to bind CisPt, also simultaneously with Cu. The Atox1-CisPt complexes were further probed using selected mutants in studies demonstrating that only the two cysteines (Cys12 and Cys15) in the Cu-binding site of Atox1 are essential for CisPt interactions. A proposed Atox1 di-metal complex containing both Cu and CisPt was found to be monomeric, and no loss of Cu was observed. In vitro experiments demonstrated that CisPt could also bind to metal-binding domain 4 of ATP7B (WD4), and that the drug could be transferred from Atox1 to the domain. These findings indicated that Atox1 may transfer CisPt to ATP7A/B in vivo, utilizing the same transport pathway as Cu. However, the CisPt-bound Atox1 complexes were not stable over time; upon incubation, protein unfolding and aggregation were observed. Thus, in vivo, Atox1 might alternatively be a dead-end sink for CisPt.

      The effects of the ligands around the Pt-center of Pt-based anticancer drugs and drug derivatives on Atox1 binding and unfolding were also investigated. The ligands’ chemistry and geometry were shown to dictate the extent and rate of the Pt-based substances interactions with Atox1. Finally, the occurrence of Atox1-CisPt interactions in a biological environment was demonstrated by developing and applying an antibody-based method allowing analysis of metals associated with Atox1 extracted from CisPt-treated cells.

      The findings presented in this thesis show that CisPt binds to Atox1 and WD4, also simultaneously with Cu, in vitro. The results support the hypothesis that Cu-transporting proteins can mediate cellular resistance to CisPt in vivo, and provide a deeper chemical understanding of the interactions between the proteins and the drug.

  • 21.
    Feng, Wenting
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Klaminder, Jonatan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Boily, Jean-Francois
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Thermal Stability of Goethite-Bound Natural Organic Matter Is Impacted by Carbon Loading2015In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 119, no 51, p. 12790-12796Article in journal (Refereed)
    Abstract [en]

    Dissolved natural organic matter (NOM) sorption at mineral surfaces can significantly affect the persistence. of organic carbon in soils and sediments. Consequently, determining the mechanisms that stabilize sorbed NOM is crucial for predicting the persistence of carbon in nature. This study determined the effects of loadings and pH on the thermal stability of NOM associated: With synthetic goethite (alpha-FeOOH) particle surfaces, as a proxy for NOM mineral interactions taking place in nature.. NOM thermal stability was investigated using temperature programmed desorption (TPD) in the 30-700 degrees C range to collect vibration spectra of thermally decomposing goethite NOM assemblages, and to concomitantly analyze evolved gases using mass spectrometry Results showed that NOM thermal stability, indicated by the range of temperatures in which CO2 evolved during thermal decomposition, was greatest in unbound NOM and lowest when NOM was bound to goethite. NOM thermal Stability was also loading dependent. It decreased:when loadings were in increased the 0.01 to 042 mg C m(-2) range, where the upper value corresponds to a Langmuirian adsorption maximum. Concomitant Fourier transform infrared (FTIR) spectroscopy measurement showed that these lowered stabilities could be ascribed to direct NOM-goethite interactions that dominated the NOM binding environment. Mineral surface interactions at larger loadings involved, on the contrary, a smaller fraction of the sorbed NOM, thus increasing thermal stability toward that of its unbound counterpart. This study thus identifies a sorption threshold below which NOM sorption to goethite decreases NOM thermal stability, and above which no strong effects are Manifested. This should likely influence the fate of organic carbon exposed to thermal gradients in natural environments.

  • 22.
    Ferro, Lorenza
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gentili, Francesco G.
    Funk, Christiane
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Isolation and characterization of microalgal strains for biomass production and wastewater reclamation in Northern Sweden2018In: Algal Research, ISSN 2211-9264, Vol. 32, p. 44-53Article in journal (Refereed)
    Abstract [en]

    Microalgal strains adapted to the harsh Nordic climate were isolated from Swedish fresh- and wastewater sources and tested for their ability to grow in municipal wastewater. The 62 strains able to grow in municipal wastewater belonged to 12 different genera, of those DesmodesmusScenedesmus and Chlorella were most representative. Eight axenic strains were further characterized, all of which could efficiently remove nitrogen (>90%) and phosphate (>99%) from the wastewater in less than two weeks. The microalga Coelastrellasp. had the highest performance in terms of both biomass concentration and total lipid content (1.46 g/L, 30.8%) after 13 days of cultivation. This is the first report of a Coelastrellastrain isolated in Sweden. Even Chlorella vulgaris performed very well with a biomass concentration and total lipid content of 1.15 g/L and 34.2%, respectively. Finally, two Desmodesmus sp. strains showed desirable traits for biofuel-feedstock, due to their fast growth rates (1.18 and 1.08 d−1) together with high oil content (29.8% and 36.7% of DW).

  • 23.
    Gustafsson, Asa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Swetox, Karolinska Institutet, Unit of Toxicology Sciences, Forskargatan 20, SE-151 36 Södertälje, Sweden.
    Krais, Annette M.
    Gorzsás, András
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lundh, Thomas
    Gerde, Per
    Isolation and characterization of a respirable particle fraction from residential house-dust2018In: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 161, p. 284-290Article in journal (Refereed)
    Abstract [en]

    Indoor air pollution has caused increasing concern in recent years. As we spend most of our lives indoors, it is crucial to understand the health effects caused by indoor air pollution. Household dust serve as good proxy for accessing indoor air pollution, especially smaller dust particles that can pass into the lungs are of interest. In this study we present an efficient method for the isolation of dust particles in the respirable size range. The respirable fraction was recovered from vacuum cleaner bags, separated by stepwise sieving, followed by characterization for size, morphology, surface area, organic content and elemental composition. The respirable fraction was obtained in a yield of 0.6% with a specific surface area of 2.5 m(2)/g and a Mass Median Aerodynamic Diameter of 3.73 +/- 0.15 mu m. Aluminum and zink were the dominating metals measured in the dust, whereas the major mineral components were found to be silicon dioxide and calcium carbonate. The fraction of organic matter in the dust was measured to be 69 +/- 1%. The organic matrix contained bacterial and fungi and a presence of skin fragments. We present here an efficient and fast method for the isolation of dust particles in the respirable size range. That is of considerable value due to the need for large quantities of respirable particle fractions to conduct toxicological studies and risk assessment work.

  • 24.
    Heinze, Thomas
    et al.
    Friedrich Schiller University of Jena.
    et al., et al.
    Friedrich Schiller University of Jena.
    Cellulose Carbonates: A Platform for Promising Biopolymer Derivatives with Multifunctional Capabilities2016Conference paper (Other academic)
    Abstract [en]

    In addition to cellulose tosylates (Heinze et al 2016), cellulose carbonates represent a new type of platform compounds that open new possibilities for the design of advanced materials based on the most important renewable resource cellulose. In addition, the synthesis concept can be used for polysaccharides in general that could be proofed for starch and dextran carbonates. In the presentation, the efficient preparation of well-soluble cellulose carbonates is discussed based on own research program about organo-soluble and reactive polysaccharide derivatives. Homogeneous procedures are most efficient applying typical cellulose solvents including N,N-dimethylacetamide (DMAc)/LiCl and ionic liquids (IL) in combination with organic solvents like pyridine. Even products with complete functionalization of all hydroxyl groups are available (degree of substitution, DS 3). The cellulose carbonates are commercially available from a start-up company and are well suitable for homogeneous conversion with nucleophilic compounds in particular with amines. They are easily soluble in organic solvents; thus, the time-consuming and tricky dissolution of cellulose in complex solvents can be omitted. The synthesis and aminolysis of cellulose carbonates with low, intermediate, and high DS and the evaluation of this chemistry with respect to specific challenges will be exemplarily discussed. Functional cellulose carbamates, obtained from cellulose phenyl carbonate by aminolysis, show the potential use of this class of celluloses. Immunoassays, zwitterionic polymers, products for laundry applications are included as representative examples regarding properties and application of the new cellulose-based products (Elschner and Heinze 2015) 

  • 25.
    Hernell, Olle
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Den humana mjölkens lipaser: egenskaper och fysiologiska aspekter1974Doctoral thesis, comprehensive summary (Other academic)
    Abstract [sv]

    I avhandlingen visas att:

    1.  Human mjölk innehåller två lipaser. Det ena är ett serum-stimulerat lipas (lipoprotein lipas). Lipoprotein lipaser är enzymer som har en central roll i den normala katabolismen av de triglyceridrika plasma- lipoproteinerna. Lipaset har sannolikt inte någon fysiologisk funktion i mjölken. En metod beskrivs med vilken lipaset har renats ca 9 500 gånger från mjölk.

    2.  Det serum-stimulerade lipaset från human mjölk har de klassiska egen­skaperna för ett serum-stimulerat lipas (lipoprotein lipas). Med en immunologisk metod visas att lipaset korsreagerar med motsvarande lipaser i bovin mjölk och human postheparin plasma. Slutsatsen är att det serum-stimulerade lipaset i human mjölk är väl värt att studera eftersom det mycket väl kan ha många egenskaper gemensamma med de fysiologiskt aktiva och viktiga humana serum-stimulerade lipaserna.

    3.  Det andra lipaset i human mjölk, det gallsalt-stimulerade lipaset, har en låg substratspecificitet. Gallsalter stimulerar enzymaktiviteten mot alla substrat som testats. Mot mjölkens egna triglycerider är lipaset helt inaktivt i frånvaro av gallsalter. I närvaro av gall- salter spjälkar lipaset alla tre esterbindningarna i triglycerid- molekylen så att slutprodukterna blir fria fettsyror och glycerol.

    4.  Gallsalter skyddar lipaset mot olika typer av inaktivering, t ex mot inaktivering av tarmens proteinnedbrytande enzymer. Det är sanno­likt att gallsalternas effekt beror på att de direkt interagerar med enzymproteinet. Lipaset visas ha sådana egenskaper att det väsentligt skulle kunna bidraga till den spjälkning av mjölktriglyceriderna som sker i tarmen hos den nyfödde.

  • 26.
    Idström, Alexander
    et al.
    Swerea IVF.
    Gentil, Luigi
    Lund University.
    Gubitosi, Marta
    Lund University.
    Olsson, Carina
    Swerea IVF.
    Stenqvist, Björn
    Lund University.
    Lund, Mikael
    Lund University.
    Olsson, Ulf
    Lund University.
    Köhnke, Tobias
    Swerea IVF.
    Bergquist, Karl-Erik
    Lund University.
    Dissolution of cellulose in tetrabutylammonium acetate/dimethyl sulfoxide2016In: The 7th workshop on cellulose, regenerated cellulose and cellulose derivatives, 2016Conference paper (Other academic)
    Abstract [en]

    The dissolution of cellulose in tetrabutylammonium acetate (TBAAc)/dimethyl sulfoxide (DMSO) was studied combining experimental and simulation techniques. It was found that the dissolution limit at 40 °C corresponded to a molar ratio close to one acetate per cellulose anhydroglucose units. MD simulations suggested that the acetate ions bind to cellulose by dual hydrogen bonds. This effectively turns cellulose into a polyelectrolyte, attracting the bulky tetrabutylammonium (TBA+) counter ions, which prevent close contact between chains in the dissolved state. This hypothesis was tested by 1H- and 13C-NMR spectroscopy, which confirmed that acetate forms hydrogen bonds to cellulose, and by diffusion NMR spectroscopy, which demonstrated a strong dynamic correlation between bound acetate and tetrabutylammonium in near-quantitative agreement with simulation. The present results suggest that offering hydrogen bonding to the acetate ions is the main driving force for dissolving cellulose and that the TBA+ counter ions form a diffuse layer around the acetate-decorated cellulose chains.

  • 27. Kimanius, D.
    et al.
    Lindahl, E.
    Andersson, M.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Uptake dynamics in the Lactose permease (LacY) membrane protein transporter2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 14324Article in journal (Refereed)
    Abstract [en]

    The sugar transporter Lactose permease (LacY) of Escherichia coli has become a prototype to understand the underlying molecular details of membrane transport. Crystal structures have trapped the protein in sugar-bound states facing the periplasm, but with narrow openings unable to accommodate sugar. Therefore, the molecular details of sugar uptake remain elusive. In this work, we have used extended simulations and metadynamics sampling to explore a putative sugar-uptake pathway and associated free energy landscape. We found an entrance at helix-pair 2 and 11, which involved lipid head groups and residues Gln 241 and Gln 359. Furthermore, the protein displayed high flexibility on the periplasmic side of Phe 27, which is located at the narrowest section of the pathway. Interactions to Phe 27 enabled passage into the binding site, which was associated with a 24 ± 4 kJ/mol binding free energy in excellent agreement with an independent binding free energy calculation and experimental data. Two free energy minima corresponding to the two possible binding poses of the lactose analog β-D-galactopyranosyl-1-thio-β-D-galactopyranoside (TDG) were aligned with the crystal structure-binding pocket. This work outlines the chemical environment of a putative periplasmic sugar pathway and paves way for understanding substrate affinity and specificity in LacY.

  • 28. Kong, Dexu
    et al.
    Megone, William
    Nguyen, Khai D. Q.
    Di Cio, Stefania
    Ramstedt, Madeleine
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gautrot, Julien E.
    Protein nanosheet mechanics controls cell adhesion and expansion on low-viscosity liquids2018In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 18, no 3, p. 1946-1951Article in journal (Refereed)
    Abstract [en]

    Adherent cell culture typically requires cell spreading at the surface of solid substrates to sustain the formation of stable focal adhesions and assembly of a contractile cytoskeleton. However, a few reports have demonstrated that cell culture is possible on liquid substrates such as silicone and fluorinated oils, even displaying very low viscosities (0.77 cSt). Such behavior is surprising as low viscosity liquids are thought to relax much too fast (<ms) to enable the stabilization of focal adhesions (with lifetimes on the order of minutes to hours). Here we show that cell spreading and proliferation at the surface of low viscosity liquids are enabled by the self-assembly of mechanically strong protein nanosheets at these interfaces. We propose that this phenomenon results from the denaturation of globular proteins, such as albumin, in combination with the coupling of surfactant molecules to the resulting protein nanosheets. We use interfacial rheology and atomic force microscopy indentation to characterize the mechanical properties of protein nanosheets and associated liquid–liquid interfaces. We identify a direct relationship between interfacial mechanics and the association of surfactant molecules with proteins and polymers assembled at liquid–liquid interfaces. In addition, our data indicate that cells primarily sense in-plane mechanical properties of interfaces, rather than relying on surface tension to sustain spreading, as in the spreading of water striders. These findings demonstrate that bulk and nanoscale mechanical properties may be designed independently, to provide structure and regulate cell phenotype, therefore calling for a paradigm shift for the design of biomaterials in regenerative medicine.

  • 29.
    Kuba, Matthias
    et al.
    Technische Universität Wien, Institute of Chemical Engineering.
    He, Hanbing
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Kirnbauer, Friedrich
    Technische Universität Wien, Institute of Chemical Engineering.
    Skoglund, Nils
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Hofbauer, Hermann
    Technische Universität Wien, Institute of Chemical Engineering.
    Mechanism of Layer Formation on Olivine Bed Particles in Industrial-Scale Dual Fluid Bed Gasification of Wood2016In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, no 9, p. 7410-7418Article in journal (Refereed)
    Abstract [en]

    Utilization of biomass as feedstock in dual fluidized bed steam gasification is a promising technology for the substitution of fossil energy carriers. Experience from industrial-scale power plants showed an alteration of the olivine bed material due to interaction with biomass ash components. This change results mainly in the formation of Ca-rich layers on the bed particles. In this paper, a mechanism for layer formation is proposed and compared to the better understood mechanism for layer formation on quartz bed particles. Olivine bed material was sampled at an industrial-scale power plant before the start of operation and at predefined times after the operation had commenced. Therefore, time-dependent layer formation under industrial-scale conditions could be investigated. The proposed mechanism suggests that the interaction between wood biomass ash and olivine bed particles is based on a solid–solid substitution reaction, where Ca2+ is incorporated into the crystal structure. As a consequence, Fe2+/3+ and Mg2+ ions are expelled as oxides. This substitution results in the formation of cracks in the particle layer due to a volume expansion in the crystal structure once Ca2+ is incorporated. The results of this work are compared to relevant published results, including those related to quartz bed particles.

  • 30. Lage, Sandra
    et al.
    Gojkovic, Zivan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Funk, Christiane
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gentili, Francesco G.
    Algal Biomass from Wastewater and Flue Gases as a Source of Bioenergy2018In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 3, article id 664Article, review/survey (Refereed)
    Abstract [en]

    Algae are without doubt the most productive photosynthetic organisms on Earth; they are highly efficient in converting CO2 and nutrients into biomass. These abilities can be exploited by culturing microalgae from wastewater and flue gases for effective wastewater reclamation. Algae are known to remove nitrogen and phosphorus as well as several organic contaminants including pharmaceuticals from wastewater. Biomass production can even be enhanced by the addition of CO2 originating from flue gases. The algal biomass can then be used as a raw material to produce bioenergy; depending on its composition, various types of biofuels such as biodiesel, biogas, bioethanol, biobutanol or biohydrogen can be obtained. However, algal biomass generated in wastewater and flue gases also contains contaminants which, if not degraded, will end up in the ashes. In this review, the current knowledge on algal biomass production in wastewater and flue gases is summarized; special focus is given to the algal capacity to remove contaminants from wastewater and flue gases, and the consequences when converting this biomass into different types of biofuels.

  • 31.
    Le, Van Anh
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    SOURCES OF DIOXINS TO BALTIC AIR Volatilization and Resuspension As Potential Secondary Sources of Dioxins to Air2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Persistent organic pollutants (POPs) are ubiquitous contaminants characterized by semi-volatility, low water solubility, high lipophilicity and inherent toxicity. A combination of these properties results in long-rang transport, bioaccumulation and biomagnification through food webs. Elimination of the production, use and emissions of these POPs has been ongoing since the 1970s. However, the levels of some POPs are still unacceptably high in some parts of the environment and due to their high persistence levels only decline very slowly over a long period of time. This is especially true for POPs in the Baltic Sea due to long water residence time of approximately 40 years. Numerous studies have been carried out to explore the behavior and fate of the POPs in Baltic regions using analytical methods or modeling approaches.

    Air-soil exchange plays an important role in controlling the environmental fate of POPs in surface media. Air is a transport medium, which spreads chemicals far away from sources. Soils have received an input of POPs from the atmosphere over a long time period. These chemicals have accumulated in soil solids and, as primary emissions are released, can potentially be rereleased to other environmental media. Therefore, soil could become a significant "secondary" source of some POPs to the air. In this study, the aim was to determine if volatilization and/or resuspension are potential sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) ("dioxins") to Baltic air. Sources of these compounds to Baltic air are particularly interesting because levels of dioxins in fatty fish in the Baltic exceed the levels that are considered fit for human consumption in the European Union guideline.

    The fugacity quotient approach has been previously shown to be a useful method for exploring the equilibrium status of two connected environmental compartments. Fugacity quotients between the atmosphere and soil are calculated for seventeenth toxic 2, 3, 7, 8,-substituted dioxin congeners . A multimedia mass balance model designed for the Baltic Sea region (POPCYCLING-Baltic) is also employed to study the long-term exchange between air and soil. Estimated fugacity ratios from model simulations are compared with calculated fugacity quotients. Moreover, sensitive analysis is undertaken in order to evaluate the relative effect of background concentration, resuspension and bioturbation transport to the transfer flux from soil to air.

    Master’s Thesis 2011

    II

    Fugacities of dioxins in soil are additionally measured directly using equilibrium passive sampling devices. Among available passive samplers, polyoxymethylene 17 μm (POM-17) are chosen to absorb freely dissolved PCDD/Fs molecules in soil. Total soil concentrations are measured to provide input data for the POPCYCLING-Baltic multimedia fate and transport model. Estimated fugacities of dioxins will be compared with directly "measured" fugacities in soil. The predictive ability of the model is assesses by comparing estimated and "measured" fugacity.

    Calculated fugacity quotients showed that lower chlorinated dibenzofuran are close to equilibrium between soil and air while other congeners show disequilibrium. Estimated soil/air fugacity ratios are higher than one but soil still accumulates dioxins because transport process is very slow and non-equilibrium can be maintained for a long period of time. Due to the seasonal variation in concentration, volatilization is higher in summer than in winter. Therefore, net gaseous flux between soil and air can be observed in summer.

    Sensitivity analysis revealed that volatilization flux is proportional to background soil concentration. High background soil concentration results in high volatilization fluxes and vice versa. The simulation showed that the contribution of resuspension flux to air pollution levels is relatively small in comparison to the influence of variation in background soil concentration. If relatively high and unrealistic resuspension velocities are used as inputs in the model, resuspension is a significant source to the atmosphere. In contrast to background soil concentration and resuspension, bioturbation has no effect on volatilization flux even though high bioturbation rates are used as model inputs. In conclusion, except for light congeners, soil is still a sink of PCDD/Fs present in Baltic air. However, the increase in soil/air fugacity ratios suggest an increasing important of soil-to-air transport in the near future.

    Equilibrium passive samplers using POM strips are considered as a very simple, reproducible, and inexpensive partitioning method. However, the largest disadvantage of using passive samplers for dioxins is the long time to reach equilibrium. It takes 6 months for PCDD/Fs to obtain equilibrium between soil and POM strips, which exceeded the time for doing a 45 credit thesis. The analytical phase of the experiment is still on-going, and thus it was not possible to include the experimental results in this study.

     

     

     

     

  • 32. Lilienthal, Hellmuth
    et al.
    Korkalainen, Merja
    Andersson, Patrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Viluksela, Matti
    Developmental exposure to purity-controlled polychlorinated biphenyl congeners (PCB74 and PCB95) in rats: Effects on brainstem auditory evoked potentials and catalepsy2015In: Toxicology, ISSN 0300-483X, E-ISSN 1879-3185, Vol. 327, p. 22-31Article in journal (Refereed)
    Abstract [en]

    Whereas the effects of dioxin-like polychlorinated biphenyls (DL-PCBs) are well described, less is known about non-dioxin-like PCBs (NDL-PCBs), including influences on the nervous system and related behavioral effects after developmental exposure. Following the examination of the highly purified NDL congeners PCB52 and PCB180, we report here the results of experiments with PCB74 and PCB95. Rat dams were orally exposed to equimolar doses of either congener (40 mu mol/kg bw - 11.68 mg PCB74/kg bw or 13.06 mg PCB95/kg bw) from gestational day (GD) 10 to postnatal day (PND) 7. Control dams were given the vehicle. Adult offspring were tested for cataleptic behavior after induction with haloperidol, a classical neuroleptic drug, and brainstem auditory evoked potentials (BAEPs), using clicks and tone pips of different frequencies for stimulation. Results revealed slight effects on latencies to movement onset in female offspring exposed to PCB74, whereas PCB74 males and offspring exposed to PCB95 were not affected. Pronounced changes were observed in BAEPs at low frequencies in PCB74 offspring, with elevated thresholds in both sexes. PCB95 increased thresholds in males, but not females. Small effects were detected on latency of the late wave IV in both sexes after developmental exposure to PCB74 or PCB95. Compared with the other NDL-PCB congeners tested, PCB74 caused the most pronounced effects on BAEPs. (C) 2014 Elsevier Ireland Ltd. All rights reserved.

  • 33.
    Lindström, Anton
    Umeå University, Faculty of Science and Technology, Chemistry.
    A multivariate approach to characterization of drug-like molecules, proteins and the interactions between them2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A disease is often associated with a cascade reaction pathway involving proteins, co-factors and substrates. Hence to treat the disease, elements of this pathway are often targeted using a therapeutic agent, a drug. Designing new drug molecules for use as therapeutic agents involves the application of methods collectively known as computer-aided molecular design, CAMD. When the three dimensional (3D) geometry of a macromolecular target (usually a protein) is known, structure-based CAMD is undertaken and structural information of the target guides the design of new molecules and their interactions with the binding sites in targeted proteins. Many factors influence the interactions between the designed molecules and the binding sites of the target proteins, such as the physico-chemical properties of the molecule and the binding site, the flexibility of the protein and the ligand, and the surrounding solvent.

    In order for structure-based CAMD to be successful, two important aspects must be considered that take the abovementioned factors into account. These are; i) 3D fitting of molecules to the binding site of the target protein (like fitting pieces of a jigsaw puzzle), and ii) predicting the affinity of molecules to the protein binding site.

    The main objectives of the work underlying this thesis were: to create models for predicting the affinity between a molecule and a protein binding site; to refine the geometry of the molecule-protein complex derived by or in 3D fitting (also known as docking); to characterize the proteins and their secondary structure; and to evaluate the effects of different generalized-Born (GB) and Poisson-Boltzmann (PB) implicit solvent models on the refinement of the molecule-protein complex geometry created in the docking and the prediction of the molecule-to-protein binding site affinity. A further objective was to apply chemometric methodologies for modeling and data analysis to all of the above. To summarize, this thesis presents methodologies and results applicable to structure-based CAMD.

    Results show that predictive chemometric models for molecule-to-protein binding site affinity could be created that yield comparable results to similar, commonly used methods. In addition, chemometric models could be created to model the effects of software settings on the molecule-protein complex geometry using software for molecule-to-binding site docking. Furthermore, the use of chemometric models provided a more profound understanding of protein secondary structure descriptors.

    Refining the geometry of molecule-protein complexes created through molecule-to-binding site docking gave similar results for all investigated implicit solvent models, but the geometry was significantly improved in only a few examined cases (six of 30). However, using the geometry-refined molecule-protein complexes was highly valuable for the prediction of molecule-to-binding site affinity. Indeed, using the PB solvent model it yielded improvements of 0.7 in correlation coefficients (R2) for binding affinity parameters of a set of Factor Xa protein drug molecules, relative to those obtained using the fitting software.

  • 34.
    Lundholm, Karin
    Umeå University, Faculty of Science and Technology, Applied Physics and Electronics.
    Fate of Cu, Cr, As and some other trace elements during combustion of recovered waste fuels2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The increased use of biomass and recovered waste fuels in favor of fossil fuels for heat and power production is an important step towards a sustainable future. Combustion of waste fuels also offers several advantages over traditional landfilling, such as substantial volume reduction, detoxification of pathological wastes, and reduction of toxic leaches and greenhouse gas (methane) formation from landfills. However, combustion of recovered waste fuels emits more harmful trace elements than combustion of other fuels. These elements are distributed between bottom ash, fly ash and flue gas, depending on the elements partitioning and enrichment behavior. Volatilized harmful trace elements are mainly enriched in the submicron fly ash fraction. If emitted to the atmosphere, submicron particles can penetrate deep into the alveoli of the lungs, causing severe impacts on human health. Consequently, to reduce ash related problems and to control the emissions to the atmosphere, there is an increased need for understanding the physicochemical processes involved in ash transformation, including particle formation.

    The objective of this thesis was to carefully and systematically study the fate of trace elements during combustion, i.e. the chemical form of the elements and the partitioning behavior, by means of chemical equilibrium model calculations, X-ray diffraction, microscopy techniques and various spectroscopy methods. The influence of some fuel additives was also analyzed. Primarily, the elements copper, chromium and arsenic were studied.

    An initial review and evaluation of the content of thermodynamical data in commercial thermochemical databases used for chemical equilibrium model calculations showed that there was a significant difference in number of included phases and species between databases. Thermodynamical data also differed between databases, although in general less for condensed phases than for gaseous species. A state-of-the-art database for Cu, Cr and As was compiled and used for further chemical equilibrium model calculations. The fate of Cu, Cr and As was determined in combustion experiments on wood impregnated with copper, chromium and arsenic (CCA) in a bench scale reactor (15 kW). The results showed that global chemical equilibrium model calculations predicted the overall fate of Cu, Cr and As in bottom ash and ash particles quite well. However, compared to the experimental results the global model overpredicted the formation of refractory calcium arsenates, thus the arsenic volatilization was found to be higher then the predicted volatilization. In terms of chromium volatility, copper was found to be an important refractory element forming stable CuCrO2(s) and CuCr2O4(s) that suppressed the formation of CrO2(OH)2(g). The retention and speciation of Cu, Cr and As in bottom ash was further determined from combustion experiments of CCA wood fuel particles in a single particle reactor. Local chemical equilibrium model calculations were performed to simulate the combustion stages of a burning CCA treated wood fuel particle: drying, devolatilization, char burning and post-combustion. The results from the work showed that a mix of global and local chemical equilibrium model calculations is needed to describe the reality and that the combustion stages are partially overlapping. The fate of harmful trace elements, including Cu, Cr and As, was finally studied in full scale (65 MW) combustion experiments. Particles from the raw flue gas emissions were sampled and analyzed. The comparison with chemical equilibrium model calculations showed that the model explained the results well, but due to lack of thermodynamic data for K2ZnCl4(s), the formation of this phase could not be predicted.

  • 35.
    Minh Dang, Vu
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Exposure assessment of Benzo[a]pyrene for Ho Chi Minh City residents - a CalTOX modeling approach2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The potential risk for cancer cause due to exposure of Benzo[a]pyrene (BaP) (Fig.1) is a national concerning due to the increasing emission of BaP in urban areas. It is difficult and time consuming to determine BaP in all environmental compartments to assess potential human exposure. A multimedia transport and multi pathway model (CalTOX) was used to determine the concentration of BaP in all environmental compartments as well as evaluating the differences in exposure between children and adults in Ho Chi Minh City (HCMC). A range of values was used for each model input which resulted in the possible range of media concentrations and risk to BaP. A sensitivity analysis determines which influence each input parameter has on the outcome variance. The model was validated by comparison of predicted concentrations with measured concentrations in air. Uncertainty and variability analysis were also performed together to investigate their contribution to the outcome. The predicted exposure risk for a child was 2.20 times higher than for an adult. This indicates that children are important groups when calculating the exposure and risk to BaP.

  • 36.
    Nam, Kwangho
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemistry and Chemical Biology, Harvard University, Cambridge.
    Pu, Jingzhi
    Karplus, Martin
    Trapping the ATP binding state leads to a detailed understanding of the F-1-ATPase mechanism2014In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 111, no 50, p. 17851-17856Article in journal (Refereed)
    Abstract [en]

    The rotary motor enzyme FoF1-ATP synthase uses the protonmotive force across a membrane to synthesize ATP from ADP and P-i (H2PO4-) under cellular conditions that favor the hydrolysis reaction by a factor of 2 x 10(5). This remarkable ability to drive a reaction away from equilibrium by harnessing an external force differentiates it from an ordinary enzyme, which increases the rate of reaction without shifting the equilibrium. Hydrolysis takes place in the neighborhood of one conformation of the catalytic moiety F-1-ATPase, whose structure is known from crystallography. By use of molecular dynamics simulations we trap a second structure, which is rotated by 40 degrees from the catalytic dwell conformation and represents the state associated with ATP binding, in accord with single-molecule experiments. Using the two structures, we show why Pi is not released immediately after ATP hydrolysis, but only after a subsequent 120 degrees rotation, in agreement with experiment. A concerted conformational change of the alpha(3)beta(3) crown is shown to induce the 40 degrees rotation of the gamma-subunit only when the beta(E) subunit is empty, whereas with Pi bound, beta(E) serves as a latch to prevent the rotation of gamma. The present results provide a rationalization of how F-1-ATPase achieves the coupling between the small changes in the active site of beta(DP) and the 40 degrees rotation of gamma.

  • 37.
    Newton, Seth
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Atmospheric Deposition of Legacy and Emerging Persistent Organic Pollutants in Northern Sweden2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Bulk atmospheric deposition samples using Amberlite IRA- 743 as an absorbent for hydrophobic pollutants were taken every two months for one year at two different locations in northern Sweden. A method was developed for the analysis of various legacy and emerging POPs in these samples based on GC-HRMS. Two current use pesticides and four flame retardants, which have scarcely or never been detected in the arctic, were detected in the samples: trifluralin, chlorothalonil, TBECH, HBB, BTBPE, and Dechlorane Plus. Legacy compounds including isomers of HCH, PCBs, DDT and metabolites, and chlordane related compounds were quantified in levels comparable to similar studies. The method showed reasonable recoveries for all compounds except endosulfan, HBB, BTBPE, lindane, and highly chlorinated PCBs. It is recommended that the method be optimized for the compounds with low recoveries if it is to be used again.

  • 38.
    Normark, Monica
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pommer, Linda
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Gräsvik, John
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gorzsas, Andras
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Winestrand, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Biochemical Conversion of Torrefied Norway Spruce After Pretreatment with Acid or Ionic Liquid2016In: Bioenergy Research, ISSN 1939-1234, E-ISSN 1939-1242, Vol. 9, no 1, p. 355-368Article in journal (Refereed)
    Abstract [en]

    The chemical effects of torrefaction and the possibility to combine torrefaction with biochemical conversion were explored in experiments with five preparations of wood of Norway spruce that had been torrefied using different degrees of severity. Compositional analysis and analyses using solid-state CP/MAS C-13 NMR, Fourier-transform infrared (FTIR) spectroscopy, and Py-GC/MS showed small gradual changes, such as decreased hemicellulosic content and increased Klason lignin value, for torrefaction conditions in the range from 260 A degrees C and 8 min up to 310 A degrees C and 8 min. The most severe torrefaction conditions (310 A degrees C, 25 min) resulted in substantial loss of glucan and further increase of the Klason lignin value, which was attributed to conversion of carbohydrate to pseudo-lignin. Even mild torrefaction conditions led to decreased susceptibility to enzymatic hydrolysis of cellulose, a state which was not changed by pretreatment with sulfuric acid. Pretreatment with the ionic liquid (IL) 1-butyl-3-methylimidazolium acetate overcame the additional recalcitrance caused by torrefaction, and the glucose yields after 72 h of enzymatic hydrolysis of wood torrefied at 260 A degrees C for 8 min and at 285 A degrees C for 16.5 min were as high as that of IL-pretreated non-torrefied spruce wood. Compared to IL-pretreated non-torrefied reference wood, the glucose production rates after 2 h of enzymatic hydrolysis of IL-pretreated wood torrefied at 260 A degrees C for 8 min and at 285 A degrees C for 16.5 min were 63 and 40 % higher, respectively. The findings offer increased understanding of the effects of torrefaction and indicate that mild torrefaction is compatible with biochemical conversion after pretreatment with alternative solvents that disrupt pseudo-lignin-containing lignocellulose.

  • 39.
    Odabas, Nira
    et al.
    University of Natural Resources and Life Sciences Vienna (BOKU).
    Amer, Hassan
    University of Natural Resources and Life Sciences Vienna (BOKU).
    Henniges, Ute
    University of Natural Resources and Life Sciences Vienna (BOKU).
    Potthast, Antje
    University of Natural Resources and Life Sciences Vienna (BOKU).
    Rosenau, Thomas
    University of Natural Resources and Life Sciences Vienna (BOKU).
    Cellulose derivatisation – tuning and analysing the degree of substitution2016Conference paper (Other academic)
    Abstract [en]

    Pulp fibres are negatively charged by nature, but the resulting electrostatic repulsion can be changed by cationisation. This rather straightforward chemical modification will considerably broaden the application range of lignocellulosic materials, such as wood pulp fibres. The pulp fibres can be covalently modified with the same reagent that is widely used for the cationisation of starch, 2,3 epoxypropyltrimethylammonium chloride. In general, one option for the hydroxyalkylation of cellulose is in slurry processes with organic diluents.

    Using different organic solvents, the cationisation efficiency as well as on the properties of pulp can be influenced easily. In the presented study, a bleached softwood Kraft pulp was cationised in alkaline mixtures of water with dimethyl sulfoxide (DMSO), isopropanol, and tetrahydrofuran (THF). Of the systems studied, THF offered the highest reaction efficiency with respect to the achieved degree of substitution (DS). The system with DMSO was the only one that considerably decreased the molar mass of the material; the reaction efficiency was similar to a purely aqueous system. Alkaline isopropanol had the greatest impact on crystallinity and while this system increased the reaction efficiency, it was still less effective than THF. Replacing 90% of the water with THF yielded a significanly higher DS. The DS linearly depended on the concentration of reagent in respect to the present water; this was observed not only for purely aqueous systems but also for systems that contained THF. This correlation may be deployed to plan and control laboratory-scale cationisation assays.

    Tuning the DS as described above also calls for reliable analytical techniques for DS determination. The resulting materials with different DS were analysed by titration, infrared spectroscopy (IR), elemental analysis, and thermogravimetry. All the methods tested have their merits. While titration and elemental analysis are well-established reference methods with many published data, they require time-consuming pre-treatments. This can be avoided by fast and simple IR spectroscopy. However, IR spectroscopy relies on a reference method to quantify the DS. Another option explored in this work is thermogravimetry that yields additional information on water content and purity of the sample. This method, too, requires a reference method to evaluate the impact of the DS on the changed thermograms.

  • 40. Ohlin, C. André
    et al.
    Beni, Zoltan
    Laurenczy, Gábor
    Ruiz, Nuria
    Masdeu-Bulto, Anna M.
    Heterogeneous dehalogenation of arylhalides in the presence of ionic liquids2007In: Applied organometallic chemistry, ISSN 0268-2605, E-ISSN 1099-0739, Vol. 21, no 3, p. 156-160Article in journal (Refereed)
    Abstract [en]

    Dehydrohalogenation of haloaromatics in ionic liquids derived from ethylmethylimidazolium or similar salts has been performed using Pd-C, Pd(OAc)(2) and other catalysts using formate salts as a hydrogen source. In the ionic liquid [emim][BF4], chlorobenzene was dehalogenated by up to 40%, bromobenzene up to 25% and iodobenzene up to 41% in 2 h. Reactions in the absence of the ionic liquid were also performed.

  • 41.
    Palm-Espling, Maria
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, David C.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Björn, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Linusson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wittung-Stafshede, Pernilla
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Determinants for simultaneous binding of copper and platinum to human chaperone Atox1: hitchhiking not hijacking2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 7, article id e70473Article in journal (Refereed)
    Abstract [en]

    Cisplatin (CisPt) is an anticancer agent that has been used for decades to treat a variety of cancers. CisPt treatment causes many side effects due to interactions with proteins that detoxify the drug before reaching the DNA. One key player in CisPt resistance is the cellular copper-transport system involving the uptake protein Ctr1, the cytoplasmic chaperone Atox1 and the secretory path ATP7A/B proteins. CisPt has been shown to bind to ATP7B, resulting in vesicle sequestering of the drug. In addition, we and others showed that the apo-form of Atox1 could interact with CisPt in vitro and in vivo. Since the function of Atox1 is to transport copper (Cu) ions, it is important to assess how CisPt binding depends on Cu-loading of Atox1. Surprisingly, we recently found that CisPt interacted with Cu-loaded Atox1 in vitro at a position near the Cu site such that unique spectroscopic features appeared. Here, we identify the binding site for CisPt in the Cu-loaded form of Atox1 using strategic variants and a combination of spectroscopic and chromatographic methods. We directly prove that both metals can bind simultaneously and that the unique spectroscopic signals originate from an Atox1 monomer species. Both Cys in the Cu-site (Cys12, Cys15) are needed to form the di-metal complex, but not Cys41. Removing Met10 in the conserved metal-binding motif makes the loop more floppy and, despite metal binding, there are no metal-metal electronic transitions. In silico geometry minimizations provide an energetically favorable model of a tentative ternary Cu-Pt-Atox1 complex. Finally, we demonstrate that Atox1 can deliver CisPt to the fourth metal binding domain 4 of ATP7B (WD4), indicative of a possible drug detoxification mechanism.

  • 42. Privalova, Elena
    et al.
    Rasi, S.
    Mäki-Arvela, P.
    Eränen, K.
    Rintala, D.
    Murzin, D. Yu.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    CO2 capture from biogas: absorbent selection2013In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, no 9, p. 2979-2994Article in journal (Refereed)
    Abstract [en]

    The development of proper biogas upgrading technology offers a viable means to utilize biogas in conventional power systems. In this paper, various molecular and ionic solvent systems were evaluated for CO2 removal from biogas in a loop reactor system. The performance of amine solutions, ionic liquids and their mixtures, amino acid salts and solutions blended with piperazine was compared in terms of their CO2 loading capacity. The experimental results revealed that addition of small amounts of piperazine can increase the efficiency of abovementioned solutions on average by 30 vol%. The CO2 capturing capacity of the most promising solvents was in the range of 50-60 L CO2/L absorbent. The regeneration of the solvent mixtures can be challenging since the solvents could loose 16-43 vol% of their initial efficiency upon CO2 release. Ionic liquid [C4mim][acetate] was found to be an efficient VOCs scrubbing media. Moreover, upon use of this ionic liquid, the amount of identified volatile organic compounds (VOCs) in the studied samples was reduced by 65 wt%, while the use of 15 wt% aqueous N-methyldiethanolamine (MDEA) resulted only in 32 wt% reduction in the amount of VOCs.

  • 43.
    Rebbling, Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Luleå University of Technology, Department of Engineering Sciences & Mathematics, Energy Engineering.
    Understanding reactivity using fuel design - phosphorus vs kaolin in combustion of stem wood2016Conference paper (Refereed)
    Abstract [en]

    The fate of various ash-forming elements determine how well a fuel will perform in a given thermochemical energy conversion process. In order understand ash-related process problems it is particularly important in which compounds alkali metal ions, for biomass this primarily means K+ and Na+, are bonded. Their low charge and relatively large ionic radii leads to poor bond strengths in compounds where they provide the only Lewis acid component, i.e. electron acceptor. This can be remedied by trying to bond alkali metal ions to stronger, predominantly molecular Lewis bases which is the case in for instance arkanite, K2SO4 – the targeted reaction product when (NH4)2SO4 is added in the flue gas to reduce KCl formation. Another approach is to bond alkali in bottom or bed ash, by including Lewis base forming elements such as phosphorus or the additive kaolin which is dominated by kaolinite. This route attempts to promote formation of high-temperature melting compounds with at least one alkali metal ion per phosphate or other starting molecule.

    While the understanding of how phosphorus reacts in combustion process is increasing it is valuable to understand how it will react in presence of other elements or molecules that play an important role for alkali capture. This will be of interest in situations where the base fuels may be combusted with addition of sulphur or kaolin, for instance. If the base fuels has a high concentration of phosphorus the amount of additive may need to be adjusted according to what phosphates will form, and if they will form even in the presence of the amending additives. Using the inherent composition of the fuel to decide suitable strategies for additive choice or possibly co-combustion is a key component of fuel design.

    The aim of this study is to investigate the relative Lewis base potential for capture of alkali metal ions between phosphates and kaolin. This is made by adding highly available phosphorus in the form of di-ammonium hydrogen phosphate, (NH4)2HPO4, and kaolin, a mineral where kaolinite is the main constituent for capturing alkali to the fuel blend. The fuel chosen is stem wood where the amount of Lewis acid forming elements greatly surpass that of Lewis base forming elements found in the ash forming matter.

  • 44.
    Reyes, Diana Carolina Alban
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gorzsas, Andras
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Stridh, Kjell
    de Wit, Paul
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Alkalization of dissolving cellulose pulp with highly concentrated caustic at low NaOH stoichiometric excess2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 165, p. 213-220Article in journal (Refereed)
    Abstract [en]

    We present a quantitative study, using Raman spectroscopy combined with multivariate data analysis, to determine the degree of activation of softwood sulphite dissolving cellulose pulp by aqueous sodium hydroxide. We have chosen industrially relevant conditions, including low stoichiometric ratio of NaOH/Anhydroglucose Unit (AGU) <2 and highly concentrated caustic (>= 45% w/w [NaOH]). A design of experiments is used to investigate the effects of simultaneous variation of a set of key parameters on the degree of activation (i.e. transformation to alkali cellulose, denoted as DoA): (a) the NaOH/AGU stoichiometric ratio, denoted (r); (b) the concentration of NaOH, denoted [NaOH]; (c) temperature, denoted (T); and (d) reaction time, denoted (t). Solid-state C-13 CP/MAS NMR spectroscopy was applied to investigate the reproducibility of the experiments and to select the range for (t). According to the model, (r) is found to have a statistically significant effect on DoA (increasing from DoA= 6-30% at the lowest (r)=0.8, to DoA= 48-87% at the highest (r)=1.8), together with [NaOH]. The influence of [NaOH] depends strongly on (r). The other studied variables are found to be insignificant in the model and has a complicated influence on the activation. In particular, (T) is found to be unimportant in the studied range (30-60 degrees C), but increasing (t) from 5 to 25 min shows a positive influence on DoA, depending on both (r) and [NaOH]. A mercerisation mechanism that is controlled by diffusion is proposed to explain these phenomena. 

  • 45.
    Reyes Forsberg, Diana Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University.
    Stridh, Kjell
    AkzoNobel.
    de Wit, Paul P.
    AkzoNobel.
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University.
    Is there a diffusion of alkali in the activation of dissolving cellulose pulp at low NAOH stoichiometric excess?2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed)
    Abstract [en]

    We conducted a quantitative study, following the degree of activation (i.e. the transformation to alkali cellulose, denoted as DoA) over time for dissolving cellulose pulp treated with different [NaOH] at low NaOH/anhydroglucose unit stoichiometric ratio (denoted as (r) ≤ 2.6). Our quantitative approach was based on Raman spectroscopy data, evaluated by partial least squares regression modelling. The results show strong influence of the (r) on DoA (increasing from DoA= 45% at (r) = 0.8, to DoA = 85% at (r) = 2.6), and its complex dependence on [NaOH]. At (r) = 0.8 the highest DoA (DoA ≳ 60%) was found at 30% [NaOH], while at (r) =1.3 it was found at 20% [NaOH] (DoA ≳ 80%). Although activation of cellulose happens in minutes at the studied temperature (30 °C), it was found that the reaction may be slow when a low (r) is used. A gradual increase of the DoA from ≈ 30% to ≈ 70% in time was seen when samples were activated with 30% [NaOH] at (r) = 0.8. At the same (r), a similar increase of DoA from ≈ 30 % to ≈ 60 % was also observed when 40% [NaOH] was used. Slow diffusion of NaOH through poorly swollen cellulose fibres is proposed as an explanation for this phenomenon. Lastly, solid-state CP/MAS NMR measurements suggest that at a fixed temperature, the Na-Cell allomorph mostly depends on [NaOH]. However, in the transition area between Na-Cell I and Na-Cell II, its influence might be affected by (r). 

  • 46.
    Rzhepishevska, Olena I.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Limanska, Nataliia
    Galkin, Mykola
    Lacoma, Alicia
    Lundquist, Margaretha
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sokol, Dmytro
    Hakobyan, Shoghik
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Queen Mary University of London, London, UK.
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Prat, Cristina
    Ramstedt, Madeleine
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Characterization of clinically relevant model bacterial strains of Pseudomonas aeruginosa for anti-biofilm testing of materials2018In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 76, p. 99-107Article in journal (Refereed)
    Abstract [en]

    There is a great interest in developing novel anti-biofilm materials in order to decrease medical device-associated bacterial infections causing morbidity and high healthcare costs. However, the testing of novel materials is often done using bacterial lab strains that may not exhibit the same phenotype as clinically relevant strains infecting medical devices. Furthermore, no consensus of strain selection exists in the field, making results very difficult to compare between studies. In this work, 19 clinical isolates of Pseudomonas aeruginosa originating from intubated patients in an intensive care unit have been characterized and compared to the lab reference strain PAO1 and a rmlC lipopolysaccharide mutant of PAO1. The adhesion and biofilm formation was monitored, as well as cell properties such as hydrophobicity, zeta potential and motility. Two groups of isolates were observed: one with high adhesion to polymer surfaces and one with low adhesion (the latter including PAO1). Furthermore, detailed biofilm assays in a flow system were performed using five characteristic isolates from the two groups. Confocal microscopy showed that the adhesion and biofilm formation of four of these five strains could be reduced dramatically on zwitterionic surface coatings. However, one isolate with pronounced swarming colonized and formed biofilm also on the antifouling surface. We demonstrate that the biofilm properties of clinical isolates can differ greatly from that of a standard lab strain and propose two clinical model strains for testing of materials designed for prevention of biofilm formation in the respiratory tract. The methodology used could beneficially be applied for screening of other collections of pathogens to identify suitable model strains for in vitro biofilm testing.

    Statement of Significance: Medical-device associated infections present a great challenge in health care. Therefore, much research is undertaken to prevent bacterial colonization of new types of biomaterials. The work described here characterizes, tests and presents a number of clinically relevant bacterial model strains for assessing biofilm formation by Pseudomonas aeruginosa. Such model strains are of importance as they may provide better predictability of lab testing protocols with respect to how well materials would perform in an infection situation in a patient. Furthermore, this study uses the strains to test the performance of polymer surfaces designed to repel bacterial adhesion and it is shown that the biofilm formation for four out of the five tested bacterial strains was reduced.

    The full text will be freely available from 2020-06-12 00:00
  • 47.
    Rölin, Lisa
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Metallanalys i salthaltigt vatten En studie i spektrala och icke-spektrala interferenser2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 48. Salam, Abdus
    et al.
    Al Mamoon, Hassan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ullah, Md Basir
    Ullah, Shah M.
    Measurement of the atmospheric aerosol particle size distribution in a highly polluted mega-city in Southeast Asia (Dhaka-Bangladesh)2012In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 59, p. 338-343Article in journal (Refereed)
    Abstract [en]

    Aerosol particle size distribution was measured with an aerodynamic particle sizer (APS) spectrometer continuously from January 21 to April 24, 2006 in Dhaka, Bangladesh. Particles number, surface and mass distributions data were stored automatically with Aerosol Instrument Manager (AIM) software on average every half an hour in a computer attached to the APS. The grand total average of number, surface and mass concentrations were 8.2 x 10(3) +/- 7.8 x 10(3) particles cm(-3), 13.3 x 10(3) +/- 11.8 x 10(3) mu m(2) cm(-3) and 3.04 +/- 2.10 mg m(-3), respectively. Fine particles with diameter smaller than 1.0 mu m aerodynamic diameter (AD) dominated the number concentration, accounted for 91.7% of the total particles indicating vehicular emissions were dominating in Dhaka air either from fossil fuel burning or compressed natural gas (CNGs). The surface and mass concentrations between 0.5 and 1.0 mu m AD were about 56.0% and 26.4% of the total particles, respectively. Remarkable seasonal differences were observed between winter and pre-monsoon seasons with the highest monthly average in January and the lowest in April. Aerosol particles in winter were 3.79 times higher for number, 3.15 times for surface and 2.18 times for mass distributions than during the pre-monsoon season. Weekends had lower concentrations than weekdays due to less vehicular traffic in the streets. Aerosol particles concentrations were about 15.0% (ranging from 9.4% to 17.3%) higher during traffic peak hours (6:00am-8:00pm) than off hours (8:00pm-6:00am). These are the first aerosol size distribution measurements with respect to number, surface and mass concentrations in real time at Dhaka, Bangladesh.

  • 49.
    Sandberg Hiltunen, Maria
    Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    A new approach to quantify and analyse tRNA sequence dataManuscript (preprint) (Other academic)
    Abstract [en]

    A novel quantitative multivariate approach for describing and analyse tRNA sequence data is presented. This approach is based on a multivariate chemical description of each nucleoside in the sequence. 30 theoretically calculated descriptors were used to characterize 63 nucleosides, and principal component analysis was used to extract the main variation from this multivariate description. The resulting four principal properties were interpreted as (PPa) size/bulk of the nucleoside, (PPb) polarity/hydrophobicity of the nucleoside, (PPc) electronic properties of the nucleoside and (PPd)polarity and size of the ribose moiety. These principal properties may be used to translate the tRNA letter sequence data into a quantitative chemical representation. We demonstrate the use of this quantitative description with a multivariate analysis of a set of tRNA sequences. This analysis gives models that are interpretable in terms of wich sequence positions, and nucleoside properties that discriminate the different isoacceptors. This approach is applicable on all kinds of RNA sequence data and gives information that is complementary to current sequence analysis techniques.

  • 50.
    Shanmugam, Kavitha
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Upadhyayula, Venkata K.K.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Use of Liquefied Biomethane (LBM) as a Vehicle Fuel for Road Freight Transportation: A Case Study Evaluating Environmental Performance of Using LBM for Operation of Tractor Trailers2018In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 69, p. 517-522Article in journal (Refereed)
    Abstract [en]

    The environmental performance of Liquefied Biomethane (LBM) and Diesel operated Tractor Trailer (TT) is compared using the Life Cycle Assessment (LCA) study. In this study we consider, raw biogas produced from an anaerobic digestion process of a Wastewater Treatment Plant (WWTP) in Umea, Sweden, which is then upgraded and liquefied to LBM and used as a fuel for TTs. Currently, the WWTP in Umea is utilizing biogas, produced onsite for cogeneration of heat and electricity, thereby meeting its energy needs. A system expansion approach is applied where electricity and heat equivalent to amount of biogas displaced for LBM production is supplied from Swedish grid (SE) mix and incineration of wood chips respectively. Correspondingly, the biogas avoided for cogeneration of electricity and heat is accounted in the study. The equivalent functional unit chosen for the LCA study is “16,000,000 ton-km of a TT transporting products and goods”. The study is modelled using SimaPro LCA Software. The ReCiPe Midpoint (H) impact assessment methodology is used to quantify ten selected and relevant midpoint environmental impacts. When compared with Diesel TT system, LBM TT exhibits superior environmental performance in seven out of ten impact categories measured than the Diesel TT system. The highest reduction is seen in Global Warming Potential (GWP) and Fossil Depletion Potential (FDP) impacts thereby suggesting that LBM derived from raw biogas of WWTP an environmentally preferred alternative to diesel for operation of TTs. However, this value proposition can have other trade-offs such as increase in eutrophication and ecotoxicity impacts. Further, replacing diesel with LBM for TT operation may not have any significant environmental benefits when electricity is drawn from carbon intensive grid mixes (e.g. coal).

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