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  • 401.
    Driver, Gordon W
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Aqueous Brønsted–Lowry Chemistry of Ionic Liquid Ions2015Inngår i: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 16, nr 11, s. 2432-2439Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ionic liquids have become commonplace materials found in research laboratories the world over, and are increasingly utilised in studies featuring water as co-solvent. It is reported herein that proton activities, aH+, originating from auto-protolysis of H2O molecules, are significantly altered in mixtures with common ionic liquids comprised of Cl, [HSO4], [CH3SO4], [CH3COO], [BF4], relative to pure water. paH+ values, recorded in partially aqueous media as −log(aH+), are observed over a wide range (∼0–13) as a result of hydrolysis (or acid dissociation) of liquid salt ions to their associated parent molecules (or conjugate bases). Brønsted–Lowry acid–base character of ionic liquid ions observed is rooted in equilibria known to govern the highly developed aqueous chemistry of classical organic and inorganic salts, as their well-known aqueous pKs dictate. Classical salt behaviour observed for both protic and aprotic ions in the presence of water suggests appropriate attention need be given to relevant chemical systems in order to exploit, or avoid, the nature of the medium formed.

  • 402.
    Driver, Gordon W.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Huang, Yang
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Laaksonen, Aatto
    Sparrman, Tobias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wang, Yonglei
    Westlund, Per-Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Correlated/non-correlated ion dynamics of charge-neutral ion couples: the origin of ionicity in ionic liquids2017Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, nr 7, s. 4975-4988Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Proton/Fluoride spin-lattice ($T_1$) nuclear magnetic relaxation dispersion (NMRD) measurements of 1-butyl-3-methyl-$1H$-imidazolium hexa-fluorophosphate, [$C_4mim][PF_6]$, have been carried out using high field spectrometers and fast-field-cycling instrument at proton Larmor frequencies ranging from 10kHz to 40 MHz, at different temperatures. The NMRD profiles are interpreted by means of a simple relaxation model based on the inter- and intra-ionic dipole-dipole relaxation mechanism. Using an atomic molecular-ion dynamic simulation at 323 K the relevant spin dipole-dipole(DD) correlation functions are calculated. The results indicate the NMRD profiles can be rationalized using intra- and inter-ionic spin DD interactions, however, both are mainly modulated by ionic reorientation because of temporary correlations with cations, where modulation by translational diffusion plays a minor role. Reorientational dynamics of charge-neutral ion couples (i.e. $[C_4mim]^{...}[PF_6]$) and $[C_4mim]^{+}$ ions are in the nano-second (ns) time range whereas the reorientation of $[PF_6]{^-}$ is characterized by a reorientational correlation time in the pico-second (ps) regime. Based on the NMRD profiles we conclude the main relaxation mechanism for $[PF_6]{^-}$ is, due to fast internal reorientational motion, a partially averaged F-F intra and a F-H inter-ionic DD coupling as the anion resides in close proximity to its temporary oppositely charged cation partner. The F-$T_1$- NMRD data display a ns dispersions which is interpreted as being due to correlated reorientational modulations resultant from H-containing charge-neutral ion couple $[C_4mim]^{...}[PF_6]$. The analysis of ionicity is based on the free anion fraction, $f$ and it increase with temperature with $f$ $\rightarrow$ 1 at the highest temperatures investigated. The fraction is obtained from the H-F NMRD profiles as correlated-non-correlated dynamics of the ions. The analysis of $T_1$ relaxation rates of C, H, F and P at high fields cannot generally give the fraction of ion but are consistent with the interpretation based on the NMRD profiles with relaxation contributions due to DD-intra and -inter, CSA-intra (and -inter for C), including spin rotation for P. The investigation has led to a description of the mechanics governing ion transport in the title ionic liquid via identification of transient correlated/non-correlated ion dynamics.

  • 403.
    Driver, Gordon W.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Johnson, Keith E.
    Interpretation of Fusion and Vaporisation Entropies for Various Classes of Substances, with a Focus on Salts2014Inngår i: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 70, nr March 2014, s. 207-2013Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Entropies of fusion and vaporisation of a variety of elements and compounds have been derived from literature data. Fusion entropies range from low values for metals and certain cyclic hydrocarbons (e.g. cyclopentane) through modest values for salts to high values for materials undergoing drastic rearrangement or disentanglement such as aluminium chloride and n-alkanes. Entropies of vaporisation for most substances are close to the Trouton’s Law value of ∼100 J deg.-1 mol.-1, with low values for species which associate on boiling (e.g. acetic acid) and higher values signifying simple dissociation (e.g. nitrogen tetroxide) or total decomposition (e.g. some ionic liquids). The nature of inorganic and semi-organic salts in all 3 phases is discussed.

  • 404.
    Driver, Gordon W
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mutikainen, Ilpo
    The complex story of a simple Brønsted acid: Unusual speciation of HBr in an ionic liquid medium2011Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 40, nr 41, s. 10801-10803Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Crystalline solids, co-existing in equilibrium with the 3-methyl-1H-imidazolium bromohydrogenates(i) ionic liquid, have been characterised by X-ray diffraction analysis. The Brønsted acidic, homo-conjugate [H(2)Br(3)](-) anions presented are discussed in terms of their structure and reactivity, in efforts to advance the understanding of Brønsted acidity in ionic liquid media.

  • 405.
    Drott, Andreas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bouchet, Sylvain
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Skyllberg, Ulf
    SLU.
    Refining Thermodynamic Constants for Mercury(II)-Sulfides in Equilibrium with Metacinnabar at Sub-Micromolar Aqueous Sulfide Concentrations2013Inngår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, nr 9, s. 4197-4203Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An important issue in mercury (Hg) biogeochemistry is to explore the influence of aqueous Hg(II) forms on bacterial uptake, and subsequent methyl mercury formation, under iron(III) and sulfate reducing conditions. The success of this is dependent on relevant information on the thermodynamic stability of Hg-sulfides. In the present study, we determined the solubility of a commercially available HgS(s) phase, which was shown by X-ray diffraction to be a mixture of 83% metacinnabar and 17% cinnabar. At aqueous sulfide concentrations between 0.060 and 84 µM, well below levels in previous studies, we report a solubility product (log Ksp±SE) of -36.8±0.3 (HgS(s) + H+ = Hg2+ + HS-, I=0, T=25°C, pH 6-10, n=20) for metacinnabar. This value is 0.7 log units higher than previous estimates. Complementing our data with data from Paquette and Helz (1997), we took advantage of a large data set (n=65) covering a wide range of aqueous sulfide (0.06 µM-140 mM), and pH (1-11). Based on this we report refined formation constants (±SE) for the three aqueous Hg(II)-sulfide species proposed by Schwarzenbach and Widmer (1963): Hg2+ + 2HS- = Hg(SH)20; log K = 39.1±0.1, Hg2+ + 2HS- = HgS2H- + H+; log K = 32.5±0.1, Hg2+ + 2HS- = HgS22- + 2H+; log K = 23.2±0.1. Our refined log K values differ from previous estimates by 0.2-0.6 log units. Furthermore, at the low sulfide concentrations in our study we could rule out the value of -10.0 for the reaction HgS(s) + H2O = HgOHSH(aq), as reported by Dyrssén and Wedborg (1991). By establishing a solubility product for the most environmentally relevant HgS(s) phase, metacinnabar, and extending the range of aqueous sulfide concentrations to sub-µM levels, relevant for soils, sediments and waters, this study decreases the uncertainty in stability constants for Hg-sulfides, thereby improving the basis for understanding the bioavailability and mobility of Hg(II) in the environment.

  • 406. Du, Mingrun
    et al.
    Zhou, Miao
    Yao, Mingguang
    Ge, Peng
    Chen, Shuanglong
    Yang, Xigui
    Liu, Ran
    Liu, Bo
    Cui, Tian
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. State Key Laboratory of Superhard Materials, Jilin University, Changchun, PR China.
    Liu, Bingbing
    High pressure infrared spectroscopy study on C60*CS2 solvates2017Inngår i: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 669, s. 49-53Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High pressure IR study has been carried out on C-60*CS2 solvates up to 34.8 GPa. It is found that the intercalated CS2 molecules significantly affect the transformations of C-60 molecules under pressure. As a probe, the intercalated CS2 molecules can well detect the orientational ordering transition and deformation of C-60 molecules under pressure. The chemical stability of CS2 molecules under pressure is also dramatically enhanced due to the spacial shielding effet from C-60 molecules around in the solvated crystal. These results provide new insight into the effect of interactions between intercalants and fullerenes on the transformations in fullerene solvates under pressure.

  • 407. Duan, Ran
    et al.
    Westerlind, Bo S.
    Norgren, Magnus
    Anugwom, Ikenna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Finland.
    Virtanen, Pasi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Finland.
    Fibre Stress-Strain Response of High-Temperature Chemi-Thermomechanical Pulp Treated with Switchable Ionic Liquids2016Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 4, s. 8570-8588Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The removal of lignin from a high-temperature chemi-thermomechanical pulp (HT-CTMP) using a switchable ionic liquid prepared from an organic superbase (1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)), monoethanol amine (MEA), and SO2 was investigated. The objective was to measure the fibre properties before and after removal of the lignin to analyse the contributions from lignin in the HT-CTMP fibre to the tensile properties. It was found that the fibre displacement at break - measured in zero span, which is related to fibre strain at break - was not influenced by the lignin removal in this ionic liquid system when tested dry. There was a small increase in displacement at break and a reduction in tensile strength at zero span when tested after rewetting. At short span, the displacement at break decreased slightly when lignin was removed, while tensile strength was almost unaffected when tested dry. Under rewetted conditions, the displacement at break increased and tensile strength decreased after lignin removal. Nevertheless, no dramatic differences in the pulp properties could be observed. Under the experimental conditions, treatment with the ionic liquid reduced the lignin content from 37.4 to 15.5 wt%.

  • 408.
    Duc, Nguyen Thanh
    et al.
    Department of Geological Sciences, Stockholm University, 106 91 Stockholm, Sweden.
    Silverstein, Samuel
    Department of Physics, Stockholm University, 106 91 Stockholm, Sweden.
    Lundmark, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Reyier, Henrik
    Department of Water and Environmental Studies, Linköping University, 58183 Linköping, Sweden.
    Crill, Patrick
    Department of Geological Sciences, Stockholm University, 106 91 Stockholm, Sweden.
    Bastviken, David
    Department of Water and Environmental Studies, Linköping University, 58183 Linköping, Sweden.
    Automated Flux Chamber for Investigating Gas Flux at Water-Air Interfaces2013Inngår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, nr 2, s. 968-975Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aquatic ecosystems are major sources of greenhouse gases (GHG). Representative measurements of GHG fluxes from aquatic ecosystems to the atmosphere are vital for quantitative understanding of relationships between biogeochemistry and climate. Fluxes occur at high temporal variability at diet or longer scales, which are not captured by traditional short-term deployments (often in the order of 30 min) of floating flux chambers. High temporal frequency measurements are necessary but also extremely labor intensive if manual flux chamber based methods are used. Therefore, we designed an inexpensive and easily mobile automated flux chamber (AFC) for extended deployments. The AFC was designed to measure in situ accumulation of gas in the chamber and also to collect gas samples in an array of sample bottles for subsequent analysis in the laboratory, providing two independent ways of CH4 concentration measurements. We here present the AFC design and function together with data from initial laboratory tests and from a field deployment.

  • 409.
    Dulko-Smith, Beata
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Molecular dynamics studies of methylmercury interactions with the glucocorticoid receptor protein2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 410.
    Dumarey, Melanie
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Galindo-Prieto, Beatriz
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Fransson, Magnus
    Pharmaceutical Development, AstraZeneca R&D, Mölndal, Sweden.
    Josefson, Mats
    Pharmaceutical Development, AstraZeneca R&D, Mölndal, Sweden.
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    OPLS methods for the analysis of hyperspectral images—comparison with MCR-ALS2014Inngår i: Journal of Chemometrics, ISSN 0886-9383, E-ISSN 1099-128X, Vol. 28, nr 8, s. 687-696Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two new orthogonal projections to latent structures (OPLS) based methods were proposed to analyze hyperspectral images, enabling the visualization ofmultiple chemical compounds in onematrix without the need of extensive preprocessing. Both proposed methods delivered images representing the chemical distribution in the ribbon similar to the more traditional multivariate curve resolution–alternating least squares (MCR-ALS) method, but their image background was less dynamic resulting in a stronger chemical contrast. This indicated that the methods successfully removed structured variation orthogonal to the chemical information (pure spectra of individual compounds), which was confirmed by the fact that physical scattering effects caused by grooves and edges were captured in the images visualizing the orthogonal components of the model. Hereby, the OPLS-based method employing the pure spectra as weights in the OPLS algorithm was more successful in distinguishing compounds with a similar spectral signal than the transposed OPLS algorithm(pure spectra of individual compounds were used as response in OPLS model). It should be noted that for the main compounds, the MCR-ALS method enabled easier visual interpretation compared to the OPLS-based methods by setting all values below zero to zero, resulting in a higher contrast between pixels containing the studied compound and pixels not containing that compound.

  • 411.
    Dumarey, Melanie
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wikström, Håkan
    Pharmaceutical Development, AstraZeneca R&D Mölndal, Sweden .
    Fransson, Magnus
    Pharmaceutical Development, AstraZeneca R&D Mölndal, Sweden .
    Sparén, Anders
    Pharmaceutical Development, AstraZeneca R&D Mölndal, Sweden .
    Tajarobi, Pirjo
    Pharmaceutical Development, AstraZeneca R&D Mölndal, Sweden .
    Josefson, Mats
    Pharmaceutical Development, AstraZeneca R&D Mölndal, Sweden .
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Combining experimental design and orthogonal projections to latent structures to study the influence of microcrystalline cellulose properties on roll compaction2011Inngår i: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 416, nr 1, s. 110-119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Roll compaction is gaining importance in pharmaceutical industry for the dry granulation of heat or moisture sensitive powder blends with poor flowing properties prior to tabletting. We studied the influence of microcrystalline cellulose (MCC) properties on the roll compaction process and the consecutive steps in tablet manufacturing. Four dissimilar MCC grades, selected by subjecting their physical characteristics to principal components analysis, and three speed ratios, i.e. the ratio of the feed screw speed and the roll speed of the roll compactor, were included in a full factorial design. Orthogonal projection to latent structures was then used to model the properties of the resulting roll compacted products (ribbons, granules and tablets) as a function of the physical MCC properties and the speed ratio. This modified version of partial least squares regression separates variation in the design correlated to the considered response from the variation orthogonal to that response. The contributions of the MCC properties and the speed ratio to the predictive and orthogonal components of the models were used to evaluate the effect of the design variation. The models indicated that several MCC properties, e.g. bulk density and compressibility, affected all granule and tablet properties, but only one studied ribbon property: porosity. After roll compaction, Ceolus KG 1000 resulted in tablets with obvious higher tensile strength and lower disintegration time compared to the other MCC grades. This study confirmed that the particle size increase caused by roll compaction is highly responsible for the tensile strength decrease of the tablets.

  • 412.
    Duong Phan, Ngoc Chau
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Weidemann, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lundin, Lisa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Marklund, Stellan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jansson, Stina
    Swedish University of Agricultural Sciences.
    Accurate sampling of PCDD/F in high temperature flue-gas using cooled sampling probes2012Inngår i: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 88, nr 7, s. 832-836Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In a laboratory-scale combustion reactor, flue-gas samples were collected at two temperatures in the post-combustion zone, 700 °C and 400 °C, using two different water-cooled sampling probes. The probes were the cooled probe described in the European Standard method EN-1948:1, referred to as the original probe, and a modified probe that contained a salt/ice mixture to assist the cooling, referred to as the sub-zero probe. To determine the efficiency of the cooling probes, internal temperature measurements were recorded at 5 cm intervals inside the probes. Flue-gas samples were analyzed for polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs). Samples collected at 700 °C using the original cooling probe showed higher concentrations of PCDD/Fs compared to samples collected using the sub-zero probe. No significant differences were observed between samples collected at 400 °C. The results indicated that artifact formation of PCDD/Fs readily occurs during flue-gas sampling at high temperatures if the cooling within the probe is insufficient, as found for the original probe at 700 °C. It was also shown that this problem could be alleviated by using probes with an enhanced cooling capacity, such as the sub-zero probe.

    Although this may not affect samples collected for regulatory purposes in exit gases, it is of great importance for research conducted in the high-temperature region of the post-combustion zone. 

  • 413. Durgadevi, Ganesan
    et al.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Chandran, Muthaiah
    Kuppusamy, Muniyan Ramasamy
    Dinakaran, Kannaiyan
    Synthesis and characterization of CdS nanoparticle anchored Silica-Titania mixed Oxide mesoporous particles: Efficient photocatalyst for discoloration of textile effluent2019Inngår i: International Journal of Nano Dimension, ISSN 2008-8868, E-ISSN 2228-5059, Vol. 10, nr 3, s. 272-280Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient photocatalyst consisting of CdS nanoparticle dispersed mesoporous silica-titania was prepared using amphiphilic triblock copolymer P123 as template and silica-titania sol-gel precursors. The CdS nanoparticle was incorporated into silica-titania mesoporous nanosturctures by post impregnation method. The synthesized catalyst has been characterized by FTIR, TEM, SEM, and EDAX analysis. The CdS nanoparticles incorporated silica-titania mesoporous particles exhibited an enhanced light harvesting, large surface area and excellent photocatalytic activity. Photocatalytic degradation experiments on methyleneblue solution at different pH of the medium revealed that, the catalyst ST0.5CdS0.2 is more effective in basic medium with a degradation efficiency of 98%. In addition, the catalyst is also tested for dye degradation against a raw textile dye effluent containing multiple dye molecules, and their results indicated that the raw effluent can be decolorized within 90min using ST0.5CdS0.2 catalyst.

  • 414. Dyson, P J
    et al.
    Laurenczy, G
    Ohlin, C A
    Vallance, J
    Welton, T
    Determination of hydrogen concentration in ionic liquids and the effect (or lack of) on rates of hydrogenation2003Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, nr 19, s. 2418-2419Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The solubility of hydrogen and the corresponding Henry coefficients for 11 ionic liquids have been determined in situ at 100 atm H(2) pressure and are much lower than expected; attempts to correlate the solubility of hydrogen in the ionic liquids with the rate of reaction for the hydrogenation of benzene to cyclohexane in these solvents have been made.

  • 415.
    Dzwilewski, Andrzej
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Matyba, Piotr
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Edman, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Facile fabrication of efficient organic CMOS circuits2010Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 114, nr 1, s. 135-140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organic electronic circuits based on a combination of n- and p-type transistors (so-called CMOS circuits) are attractive, since they promise the realization of a manifold of versatile and low-cost electronic devices. Here, we report a novel photoinduced transformation method, which allows for a particularly straightforward fabrication of highly functional organic CMOS circuits. A solution-deposited single-layer film, comprising a mixture of the n-type semiconductor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and the p-type semiconductor poly-3-hexylthiophene (P3HT) in a 3:1 mass ratio, was utilized as the common active material in an array of transistors. Selected film areas were exposed to laser light, with the result that the irradiated PCBM monomers were photochemically transformed into a low-solubility and high-mobility dimeric state. Thereafter, the entire film was developed via immersion into a developer solution, which selectively removed the nonexposed, and monomeric, PCBM component. The end result was that the transistors in the exposed film areas are n-type, as dimeric PCBM is the majority component in the active material, while the transistors in the nonexposed film areas are p-type, as P3HT is the sole remaining material. We demonstrate the merit of the method by utilizing the resulting combination of n-type and p-type transistors for the realization of CMOS inverters with a high gain of ∼35.

  • 416.
    Edlund, Ulf
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Studier av 2-cykloaminoindener speciellt med hänsyn till prototropa omlagringar1974Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is a short review of six papers (Papers 1-6,page 5) concerning studies of enamines from 2-indanones. The unusually stable 2-(N-pyrrolidyl)indene has been studied (Paper 2 ). As a base catalyst this enamine rearranges 1-methylindene to 3-methylindene with a lower rate constant compared with triethylamine. During this 1, 3-prototropic rearrangement no hydrogen exchange was observed (Paper 1).

    Special attention has been drawn to 1,3-rearrangements ofalkyl-substituted enamines of 2-indanone. From 1-methyl-2-indanone, which was most conveniently prepared by oxidation of the corresponding indene, a series of enamines has been prepared with varying amine components. A study of the kinetic control of the formation of these enamines showed that the less substituted double-bond isomer was formed more rapidly than the other form. Furthermore, the nature of the amine group has a significant influence on the composition of the equilibrium mixture observed, but the isomeric ratios obtained were unexpected in the light of earlier investigations of enamines from 2-methylcyclohexanone (Paper l).

    A 13C NMR study of these 2-cycloaminoindenes showed that introduction of a 1-methyl substituent caused a decrease in overlap but the magnitude of this perturbation was almost independent of the variation of the amine component. Furthermore, when using pyrrolidineor hexamethyleneimine as amine parts this decrease in overlap was of a comparable magnitude with the diminished conjugation noted in the 3-methyl isomers. However, when piperidine or morpholine was used the decreased delocalization was more pronounced in the 3-methyl tautomers compared with the 1-methyl analogues (Paper6).

    One isomer, 1-methyl-2-(N-piperidyl)indene, has been shown to undergo base- as well as acid-catalyzed 1,3-tautomerizations in pyridine solvent. The isomerization rates using 1,4-diazabicyclo-(2.2.2.)octane or quinuclidine as base catalysts were considerably slower than the rate of the acid-catalyzed reaction or the base-catalyzed rearrangement rates involving alkyl-substituted indenes as substrates. This retarding effect, caused by the amine group, is in agreement with differences in pKA values obtained via simple Hückel calculation (Paper 4).

    The reaction between pyrrolidine and 1-(2-indanylidene)indan--2-one has been investigated. Two possible mechanisms were suggested for the formation of products consisting of a linear dienamine and an indenyl-substituted enamine (9:1). In the main product, isolated by recrystallization, the indenyl substituent was shown to be twisted out of conjugation. This dienamine also underwent acid-catalyzed isomerization to form the enamine product (Paper 3).

    Convenient syntheses of the pharmacologically interesting N-substituted 2-aminoindanes have also been described. The perchlorate salts of the enamines were treated with sodium borohydride in methanol to afford the desired products (Paper 5).

  • 417.
    Edlund, Ulf
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wiklund, SusanneUmeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.Antti, HenrikUmeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.Karlsson, MWingsle, G
    Batch process strategy for analysing metabolic variation controlling the growth process of hybrid aspen2005Konferanseproceedings (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    High resolution magic angle spinning proton nuclear magnetic resonance spectroscopy, {1}H HR/MAS NMR, and multivariate data analysis using batch processing, BP, was applied for the analysis of two different genotypes of poplar tree (Populus tremula L. x tremuloides Michx.), containing an antisense construct of PttMYB76 and control (wild type). A gene encoding a MYB transcription factor, with unknown function, PttMYB76, was selected from a cambial EST library of poplar tree (Populus tremula L. x remuloides Michx.) for metabonomic characterisation. The PttMYB76 gene is believed to affect different paths of the phenyl propanoid synthetic pathway. This pathway leads to the formation of S- and G-lignin, flavonoids and sinapate esters. Milled poplar samples collected at the internodes of the tree were analysed using {1}H high resolution magic angle spinning NMR spectroscopy. The application of multivariate batch processing of the NMR results revealed a growth-related gradient in the plant internode direction as well as the discrimination between the trees with down regulated PttMYB76 expression and wild type populations. This paper is focused on the potential of a new analytical multivariate approach for analysing time-related plant metabonomic data. The techniques used could, with the aid of suitable model compounds, be of high relevance to the detection and understanding of the different lignification processes within the two types of poplar tree. Additionally, the findings are highlighting the importance of applying robust and organised multivariate data analysis approaches to facilitate modelling and interpretation of complex biological data sets.

  • 418.
    Edman, Ludvig
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Shin, Joon Ho
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Robinson, Nathaniel D.
    Berggren, Magnus
    Xiao, Steven
    Light-Emitting Electrochemical Cells: Direct Probing of Doping Progression and Emission2006Inngår i: Extended abstracts – 57th Annual Meeting of the International Society of Electrochemistry, 2006, s. S7-KNKonferansepaper (Annet vitenskapelig)
  • 419.
    Edo Gimenez, Mar
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Energy Engineering, Department of Engineering Sciences & Mathematics, Luleå University of Technology, Luleå, Sweden.
    Gao, Qiuju
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Persson, Per-Erik
    Jansson, Stina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Fate of metals and emissions of organic pollutants from torrefaction of waste wood, MSW, and RDF2017Inngår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 68, s. 646-652Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Torrefaction of municipal solid waste (MSW), refuse-derived fuel (RDF), and demolition and construction wood (DC) was performed at 220°C and a residence time of 90 min in a bench-scale reactor. The levels of toxic polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) contained in emission from the torrefaction process were evaluated. In addition, main ash-forming elements and trace metals in the raw feedstock and char were determined. The use of MSW in fuel blends with DC resulted in lower PCDD and PCDF emissions after torrefaction, compared with the RDF blends. The migration of chlorine from the feedstock to the gas phase reduces the chlorine content of the char which may reduce the risk of alkali chloride-corrosion in char combustion. However, trace metals catalytically active in the formation of PCDD and PCDF remain in the char, thereby may promote PCDD and PCDF formation during subsequent char combustion for energy recovery; this formation is less extensive than when the feedstock is used.

  • 420.
    Edo Giménez, Mar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå University.
    Mixed fuels composed of household waste and waste wood: Characterization, combustion behaviour and potential emissions2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

       Incineration with energy recovery is the main disposal strategy for waste that cannot be reused or recycled, and a well-established source of energy in Europe, especially in Sweden where 2.2 Mtonnes of waste including domestic and imported municipal solid waste (MSW) and waste wood (WW) were combusted during 2015. However, owing to its inherent heterogeneous composition, inclusion of such waste in Waste-to-energy (WtE) technologies is challenging. These heterogeneities may lead to operationally-related issues in the WtE facilities and contribute to toxic emissions, which can be reduced by waste pre-treatment technologies.

       This thesis examines the variations in the composition of MSW and WW streams used as a fuel supply in WtE facilities after undergoing waste pre-treatment technologies, and the effect of fuel composition on its combustion behaviour and formation of persistent organic pollutants (POPs) such as polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The overall objective is to contribute to a more thorough understanding of the selection of waste pre-treatment technologies to mitigate harmful emissions into the atmosphere when waste fuels are combusted in WtE facilities.

       This thesis describes the high variability of contaminants in domestic and imported WW and suggests adaptation of WW pre-treatment techniques to produce fuels with a low potential for generating pollutants. A comparison of mechanical solid waste pre-treatments revealed that screening and shredding is more efficient than extrusion for reducing emissions of pollutants such as PCDDs and PCDFs in combustion. The evaluation of the combustion behaviour of MSW-based fuels showed a three-stage oxidative decomposition, and an acceleration of the decomposition of the MSW compared to the lignocellulosic materials, which may be attributed to the presence of food waste and plastics in the MSW. Combustion tests of fuel blends containing WW and MSW-based fuels with different food waste content suggested that WW, not food waste content, is the key factor for the formation of PCDDs, PCDFs, and polychlorinated biphenyls (PCB), benzenes (PCBzs) and phenols (PCPhs). Torrefaction may be a suitable technology for improving the properties of waste as a fuel e.g. due to its low PCDD and PCDF emissions.

  • 421.
    Edo Giménez, Mar
    et al.
    Umeå universitet.
    Ortuño,, N
    Conesa, J.A
    Persson, P-E
    Jansson, S
    Emissions from co-combustion of demolition and construction wood and household waste fuel blendsManuskript (preprint) (Annet vitenskapelig)
  • 422.
    Edo, Mar
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Budarin, Vitaliy
    Aracil, Ignacio
    Persson, Per-Erik
    Jansson, Stina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    The combined effect of plastics and food waste accelerates the thermal decomposition of refuse-derived fuels and fuel blends2016Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 180, s. 424-432Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mechanical treatments such as shredding or extrusion are applied to municipal solid wastes (MSW) to produce refuse-derived fuels (RDF). In this way, a waste fraction (mainly composed by food waste) is removed and the quality of the fuel is improved. In this research, simultaneous thermal analysis (STA) was used to investigate how different mechanical treatments applied to MSW influence the composition and combustion behaviour of fuel blends produced by combining MSW or RDF with wood in different ratios. Shredding and screening resulted in a more efficient mechanical treatment than extrusion to reduce the chlorine content in a fuel, which would improve its quality. This study revealed that when plastics and food waste are combined in the fuel matrix, the thermal decomposition of the fuels are accelerated. The combination of MSW or RDF and woody materials in a fuel blend has a positive impact on its decomposition.

  • 423.
    Edvinsson, Sofie
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Johansson, Susanne
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    An efficient procedure for the synthesis of formylacetic esters2012Inngår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 53, nr 50, s. 6819-6821Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient synthesis of formylacetic esters via ozonolysis of trans-beta-hydromuconic esters followed by a solid-supported triphenylphosphine reduction has been developed. In addition, an extension toward formylacetic amides and a one-pot preparation of more stable intermediates which can be used for further transformations are also described.

  • 424.
    Edwin, Aaron
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Grundström, Christin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Wai, Sun Nyunt
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Öhman, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Stier, Gunter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sauer-Eriksson, A Elisabeth
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Domain isolation, expression, purification and proteolytic activity of the metalloprotease PrtV from Vibrio cholerae2014Inngår i: Protein Expression and Purification, ISSN 1046-5928, E-ISSN 1096-0279, Vol. 96, s. 39-47Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The metalloprotease PrtV from Vibrio cholerae serves an important function for the bacteria's ability to invade the mammalian host cell. The protein belongs to the family of M6 proteases, with a characteristic zinc ion in the catalytic active site. PrtV constitutes a 918 amino acids (102kDa) multidomain pre-pro-protein that so far has only been expressed in V. cholerae. Structural studies require high amounts of soluble protein with high purity. Previous attempts for recombinant expression have been hampered by low expression and solubility of protein fragments. Here, we describe results from parallel cloning experiments in Escherichia coli where fusion tagged constructs of PrtV fragments were designed, and protein products tested for expression and solubility. Of more than 100 designed constructs, three produced protein products that expressed well. These include the N-terminal domain (residues 23-103), the PKD1 domain (residues 755-839), and a 25kDa fragment (residues 581-839). The soluble fusion proteins were captured with Ni(2+) affinity chromatography, and subsequently cleaved with tobacco etch virus protease. Purification protocols yielded ∼10-15mg of pure protein from 1L of culture. Proper folding of the shorter domains was confirmed by heteronuclear NMR spectra recorded on (15)N-labeled samples. A modified protocol for the native purification of the secreted 81kDa pro-protein of PrtV is provided. Proteolytic activity measurements suggest that the 37kDa catalytic metalloprotease domain alone is sufficient for activity.

  • 425.
    Edwin, Aaron
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Rompikuntal, Pramod
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Stier, Gunter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wai, Sun Nyunt
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Sauer-Eriksson, Elisabeth A.
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Calcium binding by the PKD1 domain regulates interdomain flexibility in Vibrio cholerae metalloprotease PrtV2013Inngår i: FEBS Open Bio, E-ISSN 2211-5463, Vol. 3, s. 263-270Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Vibrio cholerae, the causative agent of cholera, releases several virulence factors including secreted proteases when it infects its host. These factors attack host cell proteins and break down tissue barriers and cellular matrix components such as collagen, laminin, fibronectin, keratin, elastin, and they induce necrotic tissue damage. The secreted protease PrtV constitutes one virulence factors of V. cholerae. It is a metalloprotease belonging to the M6 peptidase family. The protein is expressed as an inactive, multidomain, 102 kDa pre-pro-protein that undergoes several N- and C-terminal modifications after which it is secreted as an intermediate variant of 81 kDa. After secretion from the bacteria, additional proteolytic steps occur to produce the 55 kDa active M6 metalloprotease. The domain arrangement of PrtV is likely to play an important role in these maturation steps, which are known to be regulated by calcium. However, the molecular mechanism by which calcium controls proteolysis is unknown. In this study, we report the atomic resolution crystal structure of the PKD1 domain from V. cholera PrtV (residues 755–838) determined at 1.1 Å. The structure reveals a previously uncharacterized Ca2+-binding site located near linker regions between domains. Conformational changes in the Ca2+-free and Ca2+-bound forms suggest that Ca2+-binding at the PKD1 domain controls domain linker flexibility, and plays an important structural role, providing stability to the PrtV protein.

  • 426.
    Ehlers, Ina
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    NMR studies of metabolites and xenobiotics: From time-points to long-term metabolic regulation2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Chemical species carry information in two dimensions, in their concentrations and their isotopic signatures. The concentrations of metabolites or synthetic compounds describe the composition of a chemical or biological system, while isotopic signatures describe processes in the system by their reaction pathways, regulation, and responses to external stimuli. Stable isotopes are unique tracers of these processes because their natural abundances are modulated by isotope effects occurring in physical processes as well as in chemical reactions. Nuclear magnetic resonance (NMR) spectroscopy is a prime technique not only for identification and quantification of small molecules in complex systems but also for measuring intramolecular distribution of stable isotopes in metabolites and other small molecules. In this thesis, we use quantitative NMR in three fields: in food science, environmental pollutant tracing, and plant-climate science.

    The phospholipid (PL) composition of food samples is of high interest because of their nutritional value and technological properties. However, the analysis of PLs is difficult as they constitute only a small fraction of the total lipid contents in foods. Here, we developed a method to identify PLs and determine their composition in food samples, by combining a liquid-liquid extraction approach for enriching PLs, with specialized 31P,1H-COSY NMR experiments to identify and quantify PLs.

    Wide-spread pollution with synthetic compounds threatens the environment and human health. However, the fate of pollutants in the environment is often poorly understood. Using quantitative deuterium NMR spectroscopy, we showed for the nitrosamine NDMA and the pesticide DDT how intramolecular distributions (isotopomer patterns) of the heavy hydrogen isotope deuterium reveal mechanistic insight into transformation pathways of pollutants and organic compounds in general. Intramolecular isotope distributions can be used to trace a pollutant’s origin, to understand its environmental transformation pathways and to evaluate remediation approaches.

    The atmospheric CO2 concentration ([CO2]) is currently rising at an unprecedented rate and plant responses to this increase in [CO2] influence the global carbon cycle and will determine future plant productivity. To investigate long-term plant responses, we developed a method to elucidate metabolic fluxes from intramolecular deuterium distributions of metabolites that can be extracted from historic plant material. We show that the intramolecular deuterium distribution of plant glucose depends on growth [CO2] and reflects the magnitude of photorespiration, an important side reaction of photosynthesis. In historic plant samples, we observe that photorespiration decreased in annual crop plants and natural vegetation over the past century, with no observable acclimation, implying that photosynthesis increased. In tree-ring samples from all continents covering the past 60 – 700 years, we detected a significantly smaller decrease in photorespiration than expected. We conclude that the expected “CO2 fertilization” has occurred but was significantly less pronounced in trees, due to opposing effects.

    The presented applications show that intramolecular isotope distributions not only provide information about the origin and turnover of compounds but also about metabolic regulation. By extracting isotope distributions from archives of plant material, metabolic information can be obtained retrospectively, which allows studies over decades to millennia, timescales that are inaccessible with manipulation experiments.

  • 427.
    Ehlers, Ina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Augusti, Angela
    Betson, Tatiana R.
    Nilsson, Mats B.
    Schleucher, Jürgen
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Quantification of a metabolic shift towards photosynthesisin C3 plants driven by 20th-century CO2 riseManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Terrestrial vegetation currently absorbs approximately a third of the annual anthropogenic CO2 emissions, mitigating the rise of atmospheric CO2. However,terrestrial net primary production is highly sensitive to atmospheric [CO2] and associated climatic changes. In C3-plants, which dominate terrestrial vegetation, netphotosynthesis depends on the ratio between gross photosynthesis and photorespiration, which strongly depends on [CO2]. However, our knowledge of feedbacks betweenterrestrial biomes and increasing atmospheric [CO2] is nearly entirely based on atmospheric inversion models and manipulation experiments, which do not reveal physiological mechanisms or are limited in duration and to step increases in [CO2]. By applying novel NMR (Nuclear Magnetic Resonance) spectroscopy methodology we examine isotopomer ratios of plant carbohydrates to probe shifts in the photosynthesis/photorespiration ratio in C3 plants over more than a century. Using herbarium samples of natural vascular plant species, crops and a Sphagnum species, we detect a consistent 35% increase in the 2photosynthesis/photorespiration ratio in responseto the ~100 ppm CO2 increase between approximately 1900 and 2013, with no evidencefor feedback regulation by the plants. Our data provide direct quantitative information on the “CO2 fertilization effect” over century time scales, thus addressing a major uncertainty in Earth system models, enabling improved predictions of the future [CO2] sink strength of terrestrial ecosystems. Further, relating the detected metabolic shift in crop plants to historic yield trends indicates that only a fraction of the increased net photosynthesis has translated into increased yield. Our results also demonstrate that archives of plant material contain metabolic information embedded in their isotopomer ratios covering centuries, bridging a fundamental gap between experimental plant science and paleoenvironmental studies.

  • 428.
    Ehlers, Ina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Betson, Tatiana R.
    Vetter, Walter
    Schleucher, Jürgen
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Elucidating Turnover Pathways of Bioactive Small Molecules by Isotopomer Analysis: The Persistent Organic Pollutant DDT2014Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, nr 10, s. e110648-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The persistent organic pollutant DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) is still indispensable in the fight againstmalaria, although DDT and related compounds  pose toxicological  hazards. Technical DDT contains the dichloro congenerDDD (1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethyl]benzene)   as by-product, but  DDD is also formed by  reductive degradation of DDT in the environment. To differentiate between DDD formation pathways, we applied deuterium NMR spectroscopy to measure intramolecular deuterium distributions (2H isotopomer abundances) of DDT and DDD. DDD formed in the technical  DDT synthesis was strongly deuterium-enriched at one intramolecular position, which we traced back to 2H/1H fractionation of a chlorination step in the technical synthesis.  In contrast, DDD formed by reductive degradation was strongly depleted at the same position, which was due to the incorporation of 2H-depleted hydride equivalents during reductive degradation. Thus, intramolecular isotope distributions give mechanistic information on reaction pathways, and explain a puzzling difference in the whole-molecule 2H/1H ratio between DDT and DDD. In general, our results highlight that intramolecular isotope distributions are essential to interpret whole-molecule isotope ratios. Intramolecular isotope information allows distinguishing pathways of DDD formation, which is important to identify polluters or to assess  DDT turnover in the environment. Because  intramolecular isotope data directly reflect isotope fractionation of individual chemical reactions, they are broadly applicable to elucidate transformation pathways of smallbioactive molecules in chemistry, physiology and environmental science.

  • 429.
    Ehlers, Ina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Köhler, Iris
    Wieloch, Thomas
    Vlam, Mart
    van der Sleen, Peter
    Groenendijk, Peter
    Grabner, Michael
    Seim, Andrea
    Allen, Kathryn
    Wei, Liang
    Robertson, Iain
    Marshall, John
    Zuidema, Pieter A.
    Schleucher, Jürgen
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Limited suppression of photorespiration by 20th century atmospheric CO2 increase in trees worldwideManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Forests are a key component of the global carbon and hydrological cycle and forest responses to  environmental  drivers  create  important  feedbacks  to  these  cycles.  Photosynthetic efficiency of most forest tree species is strongly limited by photorespiration, a side reaction using O2 instead of CO2 as substrate, leading to a carbon loss for the plant. Photorespiration occurs in all trees and is reduced under elevated CO2 concentrations and increased under elevated temperature. Because the CO2 concentration of the atmosphere has increased in past decades, long-lived trees may have benefited from reduced photorespiration, but the temperature increase would have been a compensating detriment; but direct quantification of long-term changes in metabolic fluxes is lacking. Realistic forecasting of responses of trees and forests to future CO2 and temperature demands quantifying the reduction of photorespiration.  In  twelve  tree  species  from  five  continents,  we  observe  that photorespiration has been reduced by the CO2 increase during the past century, but for most the reduction is smaller than predicted from plant responses in CO2 alone. Comparison with data from a combined CO2 and temperature manipulation experiment shows that the reduced response can be explained by increases in leaf temperatures, which might result directly from increased  air  temperatures  or  indirectly  from  reduced  transpirative  cooling.  These  data suggest that global warming has already inhibited plant fertilization by increasing CO2, and that biomass increases may have been smaller than deduced from measurements of the heavy carbon isotope 13C. Observation of this centennial metabolic shift in tree physiology worldwide provides new insights into forest-climate feedbacks and can be used to improve coupled climate-vegetation models.

  • 430.
    Ekman, Jenny
    et al.
    National Institute for Working Life, Umeå.
    Levin, Jan-Olof
    National Institute for Working Life, Umeå.
    Lindahl, Roger
    National Institute for Working Life, Umeå.
    Sundgren, Margit
    National Institute for Working Life, Umeå.
    Ostin, Anders
    National Institute for Working Life, Umeå.
    Comparison of sampling methods for 1,6-hexamethylene diisocyanate, (HDI) in a commercial spray box2002Inngår i: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 127, nr 1, s. 169-173Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study three different types of samplers for the determination of 1,6-hexamethylene diisocyanate in air were compared. The experimental set up was a simulation of real life conditions with spray painting operations performed inside a commercial, full sized, spray box. The sampling methods were 1-(2-methoxyphenyl)-piperazine impregnated on glass fibre filter, and the same reagent in impinger, and also dibutylamine in impinger. All analyses were performed by LC-MS-MS. The determined concentrations varied between 20 and 90 microg m(-3) with relative standard deviations from 7 to 17% for each method. No significant difference was found between the three methods using ANOVA with a significance level of alpha = 0.05.

  • 431.
    Ekspong, Joakim
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Sharifi, Tiva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Klechikov, Alexey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Gracia-Espino, Eduardo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Stabilizing Active Edge Sites in Semicrystalline Molybdenum Sulfide by Anchorage on Nitrogen-Doped Carbon Nanotubes for Hydrogen Evolution Reaction2016Inngår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, nr 37, s. 6766-6776Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Finding an abundant and cost-effective electrocatalyst for the hydrogen evolu-tion reaction (HER) is crucial for a global production of hydrogen from water electrolysis. This work reports an exceptionally large surface area hybrid catalyst electrode comprising semicrystalline molybdenum sulfi de (MoS 2+ x) catalystattached on a substrate based on nitrogen-doped carbon nanotubes (N-CNTs), which are directly grown on carbon fiber paper (CP). It is shown here that nitrogen-doping of the carbon nanotubes improves the anchoring of MoS 2+ xcatalyst compared to undoped carbon nanotubes and concurrently stabilizes a semicrystalline structure of MoS 2+ x with a high exposure of active sites for HER. The well-connected constituents of the hybrid catalyst are shown to facilitate electron transport and as a result of the good attributes, the MoS 2+ x/N-CNT/CPelectrode exhibits an onset potential of −135 mV for HER in 0.5 M H2SO4, a Tafel slope of 36 mV dec −1, and high stability at a current density of −10 mA cm −2.

  • 432. Ekwall, Björn
    et al.
    Sjöström, Michael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    MEIC evaluation of acute systemic toxicity: Part VIII. Multivariate partial least squares evaluation, including the selection of a battery of cell line tests with a good prediction of human acute lethal peak blood concentrations for 50 chemicals2000Inngår i: Atla-Alternatives to Laboratory Animals, ISSN 0261-1929, Vol. 28, s. 201-34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Multicenter Evaluation of In vitro Cytotoxicity (MEIC) programme was set up to evaluate the relevance for human acute toxicity of in vitro cytotoxicity tests. A total of 61 assays were used to test all 50 reference chemicals. The results of all the tests and the human database were presented in the first five papers of this series. An evaluation of the relevance for human acute toxicity of all submitted test results with use of hard linear regression modelling was presented in the next two papers, and demonstrated a high relevance of in vitro tests, notably tests involving human cell lines. In the present study, multivariate partial least square (PLS) modelling with latent variables analysis has been used to reach two objectives. The first objective was to study the prediction of human acute toxicity by the 61 assays. The second objective was to select a practical battery from the 61 assays, with an optimal prediction of lethal blood concentrations from human acute poisonings of the chemicals. A two-component PLS model of all 61 assays predicted three sets of lethal blood concentrations (clinical, forensic and peak concentrations) very well (R-2 = 0.77, 0.76 and 0.83, Q(2) = 0.74, 0.72 and 0.81, respectively), providing correlative evidence for a high relevance for human acute toxicity of most of the assays. The assays with human cells were highly predictive, whereas assays with Very short incubation times and non-fish ecotoxicological assays were least predictive. These findings confirm the previous results from linear regression analysis. To select an optimal battery, 24 successive PLS models of in vitro data were compared with lethal peak concentrations. The battery selection was based on 38 chemicals with reliable and relevant lethal peak concentrations. An initial PLS model of all 61 assays was used to select the 15 most predictive and most distinct assays. Subsequent PLS models were used to measure the decrease in prediction when assays were deleted from the 15-test battery, as well as the increase in prediction when some extra-predictive assays (as identified by the deletion process) were added later to an optimal two-test battery. The most predictive three-test battery (R-2 = 0.79 and Q(2) = 0.78 for all 50 chemicals) included two circumstantial assays. The most predictive and most cost-effective battery consisted of three human cell line assays, with four endpoints and two exposure times, i.e. protein content (24 hours), ATP content (24 hours), inhibition of elongation of cells (24 hours), and pH-change (7 days). This 1, 5, 9, 16 battery exclusively measures basal cytotoxicity, and is highly predictive (R-2 = 0.77 and Q(2) = 0.76 for 50 chemicals) of the actual lethal peak blood concentrations from acute poisonings in humans. The battery prediction compares favourably with the prediction of human lethal dose by a PLS model of rat and mouse 50% lethal dose (LD50) values for the 50 chemicals (R-2 = 0.65 and Q(2) = 0.64). The three assays of the battery and other promising MEIC assays should be formally validated as soon as possible. The battery can be used immediately for several non-regulatory purposes, including the high-throughput screening of potential pharmaceuticals.

  • 433.
    Elg Christoffersson, Kristina
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Dissolving pulp: Multivariate Characterisation and Analysis of Reactivity and Spectroscopic Properties2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Various chemical properties can be used to characterise dissolving pulp. The quality of the pulp must be carefully controlled to ensure that it meets the requirements for its intended use and the further processes to be applied. If it is to be used to prepare viscose, or other cellulose derivatives, the key prop-erties of the pulp are its accessibility and reactivity. The studies described in this thesis investigated the potential utility of multivariate analysis of chemi-cal and spectral data for determining the properties of dissolving pulp. Dis-solving pulps produced by a two-stage sulfite process, both in the laboratory and a factory were produced pulps for this purpose. The analyses showed that pulp with high reactivity had short cellulose chains, low molecular weight, low polydispersity, low hemicellulose content, high content of ace-tone-extractable compounds, and high surface charge compared to pulp with low reactivity. Important chemical properties of the pulp, such as viscosity and alkali resistance, were successfully predicted from near infrared spectra. Predicting the reactivity, or the viscose filterability, of the pulp was more complex. Several chemical methods for analyzing the reactivity of the pulp were examined. The influence of the cellulose structure at the supermolecu-lar level on the reactivity of the pulp was explored by multivariate analysis of solid state 13C nuclear magnetic resonance spectra. Structural variables considered included: differences in hydrogen bonding, contents of hemicel-lulose, amorphous cellulose and crystalline cellulose I and II. Pulps with high reactivity have higher contents of cellulose I and amorphous cellulose than pulps with low reactivity, which have higher contents of cellulose II and hemicellulose.

  • 434.
    Elg Christoffersson, Kristina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Hauksson, Jón
    Edlund, Ulf
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sjöström, Michael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Dolk, Matti
    Characterisation of dissolving pulp using designed process variables, NIR and NMR spec-troscopy, and multivariate analysis1999Inngår i: Cellulose, Vol. 6, s. 233-249Artikkel i tidsskrift (Fagfellevurdert)
  • 435.
    Elg Christoffersson, Kristina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sjöström, Michael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Edlund, Ulf
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Agnemo, Roland
    Chemical properties and cellulose su-permolecular structure of dissolving pulps with different reac-tivity revealed by solid state NMR, NIR spectra and multivari-ate data analysisManuskript (Annet vitenskapelig)
  • 436.
    Elg Christoffersson, Kristina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sjöström, Michael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Edlund, Ulf
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lindgren, Åsa
    Dolk, Matti
    Reactivity of dissolving pulp: characterisation using chemical properties, NMR spectroscopy and multivariate data analysis2002Inngår i: Cellulose, Vol. 9, nr 2, s. 159-70Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The reactivity of dissolving pulp was experimentally determined in termsof residual cellulose in viscose. The correlations between 11 chemicalproperties of pulp and filter values and residual cellulose contents of viscosewere then investigated by multivariate data analysis. Both the viscose filtervalue and the residual cellulose were well modelled from the 11 propertiesby partial least squares regression. The results show that pulps with highacetone extractable fractions, high magnesium contents, low alkali resistanceand low viscosity, gave low viscose filter values and low residual cellulosecontents. Pulps with low residual cellulose contents also had low carboxylgroupcontents and low polydispersity. The results are interpreted as that in pulpwith high reactivity, the hemicellulose content is low and that the cellulosechains are shorter and more soluble in alkali. An explanation of the positiveeffect from the high extractive content is that the extractives facilitate thediffusion of carbon disulfide. A principal component analysis of CP/MAS13C-NMR spectral data of six pulp samples showed that differences inreactivity between the pulps could be explained by variations in the hydrogenbonds in the cellulose and/or changes in the glucosidic bonds. In a separatestudy electron beam processing enhanced the reactivity, i.e. lowered theresidual cellulose content, of the investigated pulps. The magnitude of theelectron dose, within the tested range (5.4–23.7 kGy), didnotseem to be important, but the reactivity within pulp sheets tended to be ratherinhomogeneous.

  • 437.
    Elg Christoffersson, Kristina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sjöström, Michael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Edlund, Ulf
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lindgren, Åsa
    Dolk, Matti
    Reactivity of dissolving pulp: characterisation using chemical properties, NMR spectros-copy and multivariate data analysis2002Inngår i: Cellulose, Vol. 9, s. 159-170Artikkel i tidsskrift (Fagfellevurdert)
  • 438.
    Elhaj, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Porous Polymeric Monoliths by Less Common Pathways: Preparation and Characterization2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis focuses on my endeavors to prepare new porous polymeric monoliths that are viable to use as supports in flow-through processes. Polymer monoliths of various porous properties and different chemical properties have been prepared utilizing the thermally induced phase separation (TIPS) phenomenon and step-growth polymerization reactions. The aim has been to find appropriate synthesis routes to produce separation supports with fully controlled chemical, physical and surface properties. This thesis includes preparation of porous monolithic materials from several non-cross-linked commodity polymers and engineering plastics by dissolution/precipitation process (i.e. TIPS). Elevated temperatures, above the upper critical solution temperature (UCST), were used to dissolve the polymers in appropriate solvents that only dissolve the polymers above this critical temperature. After dissolution, the homogeneous and clear polymer-solvent solution is thermally quenched by cooling. A porous material, of three dimensional structure, is then obtained as the temperature crosses the UCST. More than 20 organic solvents were tested to find the most compatible one that can dissolve the polymer above the UCST and precipitate it back when the temperature is lowered. The effect of using a mixture of two solvents or additives (co-porogenic polymer or surfactant) in the polymer dissolution/precipitation process have been studied more in depth for poly(vinylidine difluoride) (PVDF) polymers of two different molecular weight grades. Monolithic materials showing different pore characteristics could be obtained by varying the composition of the PVDF-solvent mixture during the dissolute­ion/precipitation process. Step-growth polymerization (often called polycondensat­ion reaction) combined with sol-gel process with the aid of porogenic polymer and block copolymer surfactant have also been used as a new route of synthesis for production of porous melamine-formaldehyde (MF) monoliths. In general, the meso- and macro-porous support materials, for which the synthesis/preparation is discussed in this thesis, are useful to a wide variety of applications in separation science and heterogeneous reactions (catalysis).

  • 439.
    Elhaj, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Baytekin, Mehmet
    Irgum, Knut
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Porous Melamine-Formaldehyde Monoliths by Step-Growth Polymerization Reactions via an Organic Sol-gel ProcessInngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this explorative study, twenty hydrophilic melamine-formaldehyde (MF) monolith materials were syn­the­sized by acid-catalyzed polycon­densation of systems consisting of an aqueous MF pre­condensate, a block copolymeric surfactant as main porogen, and short aliphatic polyethers as co-porogens, which were dispersed in three different organic solvents covering a wide span in polarity. The molecular size and type of aliphatic polyether (co-porogen), and of the ratio of solvents to the other components were investigated by an experimental design that resulted in monolithic materials covering a wide range of different meso- and macroporous properties. A multivariate assessment revealed that the strongest contributors to the mesopore size and the inversely related surface area were the co-porogens, whereas the macropore dimension was explained by the solvents and the ratio between solvents and the other components. Surface elemental analysis by XPS showed slight differen­ces in the bridging type between monoliths of opaque glass-like vs. white solid appearance. Measurements ζ-potentials in 10 mM ammonium acetate showed that the MF monoliths had no net charge at neutral pH, and +11 and –13 mV at pH 4 and 9.5, respectively.

  • 440.
    Elhaj, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Irgum, Knut
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Monolithic space-filling porous materials from engineering plastics by thermally induced phase separation2014Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, nr 18, s. 15653-15666Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Six different uncompounded engineering and commodity polymers were evaluated for their ability to produce space-filling monolithic entities by thermally induced phase separation (TIPS) from 22 different solvents. Attempts were first made to dissolve the polymers at elevated temperatures, selected below the boiling point of each solvent. Then the solutions of polymers that were homogeneous dissolved underwent a controlled temperature decrease to induce a phase separation as the upper critical solution temperature was passed. Twelve of the solvents gave monolithic entities by this procedure, materials that were characterized with regard to their specific surface area and pore size distribution. These measured parameters were then correlated with their macroporous morphology, assessed by scanning electron microscopy. Monolithic materials with widely different mesoporous properties were obtained with specific surface areas ranging from 169 m(2)/g to structures with essentially nonporous skeletons and distinct mesopore size distribution modes from 6 to 15 nm. The materials furthermore had a wide variation in their macroporous morphologies-among the same polymer processed in different solvents and between different polymers dissolved in the same solvent. TIPS processing therefore appears to be a viable route to prepare space-filling meso- and macroporous support materials for a wide variety of purposes in separation science and heterogeneous chemistry.

  • 441.
    Elhaj, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Irgum, Knut
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Porous Polyvinylidene Difluoride (PVDF) Monoliths via Thermally Induced Dissolution/Precipitation. Three Strategies to Pore-Tuning: Probing the possibilities of further controlling of the PVDF monolith pore formation processManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The porous properties and morphologies of the PVDF monoliths prepared via thermally induced dissolution/precipitation process were proved to be adjustable, by employing several porogenic additives to the PVDF/n-butyl butyrate matrix. PVDF monoliths have been separately precipitated from; only the main diluent (n-butyl butyrate); mixtures of the main diluent and a co-diluent; binary polymer mixtures (including an additional porogenic polymer such as poly ethylene glycol PEG200, PEG400 and poly propylene glycol PPG425); and the main diluent in the presence of a fluoro-surfactant (FSO, FSN). Their meso- and macro-porous properties were characterized by nitrogen cryoption measurements (3-5 repeated runs per sample), and a subsequent single analysis by mercury intrusion porosimetry. The visual assessment of the monoliths morphology differences were carried out using scanning electron microscopy (SEM).

  • 442.
    Elhaj, Ahmed
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Irgum, Knut
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Porous Space-filling Monolithic Polyvinylidene Difluoride (PVDF) Materials by Thermally Induced Phase SeparationInngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermally induced phase separation was assessed as a means of producing space-filling monoliths from PVDF of three dif­ferent molecular weights in twenty-two different solvents spanning a wide polarity range. Monolithic materials were produced in six out of these solvents; n-butyl butyrate, 1,4-dimethoxy­benzene, cyclohexanone, 2,5-hexanedione, dimethyl succinate, and e-caprolact­one. These monoliths had specific surface areas up to 35 m2/g, with the majority of the measured sur­face area attributable to pores in the mesoporous region from 5-20 nm, depending on solvent. Scanning elec­tron microscopy images re­vealed radically different structures at the macropore level. In three of the samples essentially monodis­perse particles in the 4-5 µm diameter range were found and verified to be of the same chemical compo­sition as the monolithic part of the precipitate. These particles appeared for PVDF of different mole­cular weights and seem to have phase separated by a mechanism dif­fering from the bulk monolith, which could hint at a novel way to prepare monodisperse PVDF particles.

  • 443.
    Eliasson, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    New strategies and tools for optimizing LC-MS data processing in metabolomics2013Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 444.
    Eliasson, Mattias
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rännar, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Madsen, Rasmus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Donten, Magdalena A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Marsden-Edwards, Emma
    Waters Corp, Milford, MA 01757 USA .
    Moritz, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Shockcor, John P
    Waters Corp, Milford, MA 01757 USA .
    Johansson, Erik
    Umetr AB, Umeå, Sweden.
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Strategy for optimizing LC-MS data processing in Metabolomics: A design of experiments approach2012Inngår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 84, nr 15, s. 6869-6876Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A strategy for optimizing LC-MS metabolomics data processing is proposed. We applied this strategy on the XCMS open source package written in R on both human and plant biology data. The strategy is a sequential design of experiments (DoE) based on a dilution series from a pooled sample and a measure of correlation between diluted concentrations and integrated peak areas. The reliability index metric, used to define peak quality, simultaneously favors reliable peaks and disfavors unreliable peaks using a weighted ratio between peaks with high and low response linearity. DoE optimization resulted in the case studies in more than 57% improvement in the reliability index compared to the use of the default settings. The proposed strategy can be applied to any other data processing software involving parameters to be tuned, e.g., MZmine 2. It can also be fully automated and used as a module in a complete metabolomics data processing pipeline.

  • 445.
    Eliasson, Mattias
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rännar, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    From data processing to multivariate validation: essential steps in extracting interpretable information from metabolomics data2011Inngår i: Current Pharmaceutical Biotechnology, ISSN 1389-2010, E-ISSN 1873-4316, Vol. 12, nr 7, s. 996-1004Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    In metabolomics studies there is a clear increase of data. This indicates the necessity of both having a battery of suitable analysis methods and validation procedures able to handle large amounts of data. In this review, an overview of the metabolomics data processing pipeline is presented. A selection of recently developed and most cited data processing methods is discussed. In addition, commonly used chemometric and machine learning analysis methods as well as validation approaches are described.

  • 446. Emilsson, Gustav
    et al.
    Röder, Evelyn
    Malekian, Bita
    Xiong, Kunli
    Manzi, John
    Tsai, Feng-Ching
    Cho, Nam-Joon
    Bally, Marta
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi. Umeå universitet, Medicinska fakulteten, Wallenberg centrum för molekylär medicin vid Umeå universitet (WCMM).
    Dahlin, Andreas
    Nanoplasmonic Sensor Detects Preferential Binding of IRSp53 to Negative Membrane Curvature2019Inngår i: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 7, artikkel-id 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biosensors based on plasmonic nanostructures are widely used in various applications and benefit from numerous operational advantages. One type of application where nanostructured sensors provide unique value in comparison with, for instance, conventional surface plasmon resonance, is investigations of the influence of nanoscale geometry on biomolecular binding events. In this study, we show that plasmonic "nanowells" conformally coated with a continuous lipid bilayer can be used to detect the preferential binding of the insulin receptor tyrosine kinase substrate protein (IRSp53) I-BAR domain to regions of negative surface curvature, i.e., the interior of the nanowells. Two different sensor architectures with and without an additional niobium oxide layer are compared for this purpose. In both cases, curvature preferential binding of IRSp53 (at around 0.025 nm(-1) and higher) can be detected qualitatively. The high refractive index niobium oxide influences the near field distribution and makes the signature for bilayer formation less clear, but the contrast for accumulation at regions of negative curvature is slightly higher. This work shows the first example of analyzing preferential binding of an average-sized and biologically important protein to negative membrane curvature in a label-free manner and in real-time, illustrating a unique application for nanoplasmonic sensors.

  • 447.
    Emtenäs, Hans
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Synthesis and biological evaluation of Bicyclic β-Lactams and 2-Pyridinones: Pilicides Targeting Pilus Biogenesis in Pathogenic Bacteria2003Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    New methods have been developed for the synthesis of bicyclic β-lactams and 2-pyridinones by combining acyl Meldrum’s acids and Δ2-thiazolines. The 2-pyridinones were synthesised both in solution using conventional heating or microwave assisted heating as well as by solid supported chemistry.

    The compounds (pilicides) were designed to interfere with the assembly of pili in uropathogenic E. coli by inhibiting the periplasmic chaperones. The affinity of the pilicides to the chaperones was investigated with surface plasmon resonance technique (Biacore) and with relaxation-edited 1H NMR spectroscopy experiments. Finally, the pilicides were investigated for their ability to inhibit pili formation in uropathogenic E. coli in a hemagglutination assay, where members of the 2-pyridinone family proved to be able to cause depiliation.

  • 448.
    Emtenäs, Hans
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Alderin, Lisa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    An Enantioselective Ketene-Imine Cycloaddition Method for Synthesis of Substituted Ring-Fused 2-Pyridinones2001Inngår i: The Journal of Organic Chemistry, Vol. 66, nr 20, s. 6756-61Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Previously, a method for the stereoselective synthesis of -lactams, starting from 2H-2-thiazolines and Meldrum's acid derivatives, has been reported from our laboratory. We now report a new method for the synthesis of optically active, highly substituted ring-fused 2-pyridinones. This was discovered when 2-alkyl-2-thiazolines and Meldrum's acid derivatives were treated with HCl(g) in benzene at 5 78 C. Further refinement of the synthetic protocol revealed that use of 1,2-dichloroethane as solvent at 0 64 C led to the desired 2-pyridinones in good yields and with excellent enantioselectivity. Use of these conditions allowed preparation of 2-pyridinones from several different 2-thiazolines and Meldrum's acid derivatives and may be a general route to 2-pyridinones.

  • 449.
    Emtenäs, Hans
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Soto, Gabe
    Hultgren, Scott J.
    Marshall, Garland R.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Stereoselective Synthesis of Optically Active β-Lactams, Potential Inhibitors of Pilus Assembly in Pathogenic Bacteria2000Inngår i: Organic Letters, Vol. 2, s. 2065-2067Artikkel i tidsskrift (Fagfellevurdert)
  • 450.
    Emtenäs, Hans
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Taflin, Camilla
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Efficient Microwave Assisted Synthesis of Optically Active Bicyclic 2-Pyridinones via Δ2-Thiazolines2003Inngår i: Molecular diversity, ISSN 1381-1991, E-ISSN 1573-501X, nr 2-4, s. 165-169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new efficient synthesis of optically active bicyclic 2-pyridiones has been developed using microwave irradiation. The synthesis is a two-step procedure via 2-thiazolines, which only requires a 3 + 2 min reaction time compared to 2 days when using conventional heating. The optimized conditions proved to be suitable for the synthesis of a small library in excellent yields and with limited racemizations.

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