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  • 1.
    Buevich, Alexei V
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lundberg, Susanne
    Sethson, Ingmar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Backman, Lars
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    NMR studies of calcium-binding to mutant alpha-spectrin EF-hands2004In: CELLULAR & MOLECULAR BIOLOGY LETTERS, ISSN 1425-8153, Vol. 9, no 1, p. 167-86Article in journal (Refereed)
    Abstract [en]

    The co-operative calcium binding mechanism of the two C-terminal EF-hands of human all-spectrin has been investigated by site-specific mutagenesis and multi-dimensional NMR spectroscopy. To analyse the calcium binding of each EF-hand independently, two mutant structures (E33A and D69S) of wild type alpha-spectrin were prepared. According to NMR analysis both E33A and D69S were properly folded. The unmutated EF-hand in these mutants remained nearly intact and active in calcium binding, whereas the mutated EF-hand lost its affinity for calcium completely. The apparent calcium binding affinity of the E33A mutant was much lower compared to the D39S mutant (similar to2470 muM and similar to240 muM, respectively). When the chemical shift perturbations were followed upon calcium titration, a positive correlation between the D69S mutant and the binding of the first calcium ion to the wild type was revealed. These observations showed that the first EF-hand in spectrin binds the first calcium ion and thereby triggers a conformational change that allows the second calcium ion to bind to the other EF-hand.

  • 2.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Studier av 2-cykloaminoindener speciellt med hänsyn till prototropa omlagringar1974Doctoral thesis, comprehensive summary (Other academic)
    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).

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  • 3.
    Edlund, Ulf
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wiklund, SusanneUmeå University, Faculty of Science and Technology, Department of Chemistry.Antti, HenrikUmeå University, Faculty of Science and Technology, Department of Chemistry.Karlsson, MWingsle, G
    Batch process strategy for analysing metabolic variation controlling the growth process of hybrid aspen2005Conference proceedings (editor) (Other (popular science, discussion, etc.))
    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.

  • 4.
    Elg Christoffersson, Kristina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hauksson, Jón
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjöström, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Dolk, Matti
    Characterisation of dissolving pulp using designed process variables, NIR and NMR spec-troscopy, and multivariate analysis1999In: Cellulose, Vol. 6, p. 233-249Article in journal (Refereed)
  • 5.
    Elg Christoffersson, Kristina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjöström, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    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 analysisManuscript (Other academic)
  • 6.
    Elg Christoffersson, Kristina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjöström, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lindgren, Åsa
    Dolk, Matti
    Reactivity of dissolving pulp: characterisation using chemical properties, NMR spectros-copy and multivariate data analysis2002In: Cellulose, Vol. 9, p. 159-170Article in journal (Refereed)
  • 7.
    Elg Christoffersson, Kristina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjöström, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lindgren, Åsa
    Dolk, Matti
    Reactivity of dissolving pulp: characterisation using chemical properties, NMR spectroscopy and multivariate data analysis2002In: Cellulose, Vol. 9, no 2, p. 159-70Article in journal (Refereed)
    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.

  • 8. Gromov, S P
    et al.
    Vedernikov, A I
    Fedorov, Yu V
    Fedorova, O A
    Andryukhina, E N
    Shepel, N E
    Strelenko, Yu A
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Saltiel, J
    Alfimov, M V
    Self-assembly of a (benzothiazolyl)ethenylbenzocrown ether into a sandwich complex and stereoselective [2+2] photocycloaddition2005In: RUSSIAN CHEMICAL BULLETIN, ISSN 1066-5285, Vol. 54, no 7, p. 1569-79Article in journal (Refereed)
    Abstract [en]

    In the presence of Ba2+ ions, (benzothiazolyl)ethenylbenzocrown ether forms the stable sandwich complex 2L center dot Ba2+ with an unusual structure, in which the benzothiazole fragments are arranged one above the other. Irradiation of the sandwich complex with visible light induces stereoselective [2+2] cycloaddition giving rise to two "head-to-head" isomers of biscrown-cyclobutane. The addition of dibasic dicarboxylic acids that additionally stabilize the sandwich complex in a favorable conformation affects the isomer ratio of the cyclobutanes formed. The conformational equilibria for the sandwich complex and cyclobutanes were studied by H-1 N MR spectroscopy.

  • 9. Gromov, Sergey P
    et al.
    Ushakov, Evgeny N
    Fedorova, Olga A
    Baskin, Igor I
    Buevich, Alexei V
    Andryukhina, Elena N
    Alfimov, Michael V
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Whitesell, James K
    Fox, Marye Anne
    Novel Photoswitchable Receptors: Synthesis and Cation-Induced Self-Assembly into Dimeric Complexes Leading to Stereospecific [2+2]-Photocycloaddition of Styryl Dyes Containing a 15-Crown-5 Ether Unit2003In: The Journal of Organic Chemistry, Vol. 68, no 16, p. 6115-25Article in journal (Refereed)
    Abstract [en]

    Styryl dyes 4a-e containing a 15-crown-5 ether unit and a quinoline residue with a sulfonatoalkyl or sulfonatobenzyl N-substituent were synthesized. The relationship between the photochemical behavior of these dyes and their aggregates derived from complexation with Mg2+ in MeCN was studied using 1H NMR and absorption spectroscopy. The E-isomers of 4a-e were shown to form highly stable dimeric (2:2) complexes with Mg2+. Upon irradiation with visible light, the dimeric complexes undergo two competing photoreactions, viz., geometric E Z isomerization, resulting in an anion-capped 1:1 complex of the Z-isomer with Mg2+ and stereospecific syn-head-to-tail [2+2]-cycloaddition, affording a single isomer of bis-crown-containing cyclobutane. The N-substituent in the dye has a dramatic effect on the photochemical behavior of the dimeric complex. Molecular dynamics and semiempirical quantum-chemical calculations were carried out to interpret the observed photocycloaddition in the dimer. Conformational equilibria for the dimer of (E)-4b were analyzed using 1H NMR spectroscopy.

  • 10. Gromov, Sergey P
    et al.
    Vedernikov, Artem I
    Ushakov, Evgeny N
    Kuz'mina, Lyudmila G
    Feofanov, Alexei V
    Avakyan, Vitaly G
    Churakov, Andrei V
    Alaverdyan, Yurii S
    Malysheva, Ekaterina V
    Alfimov, Michael V
    Howard, Judith A K
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis, Structure, Spectroscopic Studies, and Complexation of Novel Crown Ether Butadienyl Dyes2002In: Helvetica Chimica Acta, Vol. 85, no 1, p. 60-81Article in journal (Refereed)
    Abstract [en]

    Butadienyl dyes of the benzothiazole series with various fragments of benzocrown ethers 1a-c were synthesized for the first time. The structures and spectral properties of crown-containing butadienyl dyes and their complexes with alkali and alkaline-earth metal cations were studied by X-ray diffraction analysis and 1H-NMR, UV/VIS, and resonance Raman spectroscopy. To interpret the experimental results, quantum-chemical calculations were performed. In the case of Sr2+ and Ba2+ ions, the formation of strong sandwich complexes [M(1b)2]2+ of an unusual structure involving stacking interactions was established; the dye molecules are arranged one above another in the complex according to the head-to-head' pattern.

  • 11. Gromov, SP
    et al.
    Vedernikov, AI
    Ushakov, EN
    Lobova, NA
    Botsmanova, AA
    Kuz'mina, LG
    Churakov, AV
    Strelenko, YA
    Alfimov, MV
    Howard, JAK
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Novel supramolecular charge-transfer systems based on bis(18-crown-6)stilbene and viologen analogues bearing two ammonioalkyl groups2005In: NEW JOURNAL OF CHEMISTRY, ISSN 1144-0546, Vol. 29, no 7, p. 881-94Article in journal (Refereed)
    Abstract [en]

    A series of new viologen analogues bearing two ammonioalkyl groups (2-4) were synthesized in order to study their complexation with bis(18-crown-6)stilbene (1b). Electronic spectroscopy and H-1 NMR measurements show that in acetonitrile, bis( crown) stilbene 1b forms highly stable 1 : 1 and 2 : 1 charge-transfer (CT) complexes with pi-acceptors 2-4 owing to host-guest bonding. The influence of geometric and electronic factors on the complex formation constants are discussed. The structures of the supramolecular CT complexes are analyzed on the basis of H-1 and C-13 NMR data obtained in solution and in the solid state. X-Ray diffraction data for 1b and for model tetramethoxystilbene are also reported.

  • 12.
    Hauksson, Jón B
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bergqvist, Göran
    Bergsten, Urban
    Sjöström, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Prediction of basic wood properties for Norway spruce. Interpretation of Near Infrared Spectroscopy data using partial least squares regression2001In: Wood Science and Technology, ISSN 0043-7719 (Print) 1432-5225 (Online), Vol. 35, no 6, p. 475-85Article in journal (Refereed)
    Abstract [en]

    This work was undertaken to investigate the feasibility of using near infrared spectroscopy (NIR) and partial least squares regression (PLS) as a tool to characterize the basic wood properties of Norway Spruce (Picea abies (L.) Karst.). The wood samples originated from a trial located in the province of Västerbotten in Sweden. In this trial, the effects of birch shelterwoods (Betula pendula Roth) of different densities on growth and yield in Norway spruce understorey were examined. All Norway spruce trees in each shelterwood treatment were divided into three growth rate classes based on diameter at breast height (1.3 m) over bark. Five discs were cut from each tree (i.e. from the root stem, and at 20%, 40%, 60%, and 80% of the total height). The discs from 40% tree height were used (i.e., where the largest variations in annual ring widths and wood density were found). A total of 27 discs were selected. The discs were used for measuring annual ring widths, wood density, average fiber length and the fiber length distributions. Milled wood samples prepared from the discs were used for recording NIR spectra. PLS regression was used to generate prediction models for the wood properties (Y-matrix) and NIR spectra (X-matrix) as well as between the wood properties (Y-matrix) and the fiber length distributions (X-matrix). One set of models was generated using untreated spectra and fiber length distributions. For a second set of models the structure in the X-matrix, which was orthogonal to the matrix described by the wood properties, was eliminated using a soft target rotation technique called orthogonal signal correction (OSC). The PLS model obtained using "raw" untreated NIR spectra and fiber length distributions had a poor modeling power as evidenced by the cumulative Q2 values. For the PLS models based on untreated NIR spectra the cumulative Q2 values ranged from a minimum of 16% (wood density) to a maximum of 46% (no. of annual rings). Orthogonal signal correction of the X-matrix (NIR spectra or fiber length distributions) gave PLS models with a modeling power corresponding to cumulative Q2 values well in excess of 70%. The improvement in predictive ability accomplished by the OSC procedure was verified by placing four of the 27 observations in an external test set and comparing RMSEP values for the test set observations without OSC and with OSC.

  • 13.
    Hauksson, Jón B
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    NMR processing techniques based on multivariate data analysis and orthogonal signal correction. 13C CP/MAS NMR spectroscopic characterization of softwood kraft pulp2001In: Magnetic Resonance in Chemistry, Vol. 39, no 5, p. 267-75Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel way of extracting information from a series of severely overlapped NMR spectra using multivariate data analysis techniques. A number of softwood pulps were prepared from wood chips that were subjected to kraft cooking conditions in laboratory digesters. In addition to measurements of traditional physical parameters, the pulps were characterized using standard 13C CP/MAS NMR spectroscopy. The relationship between the kappa number and both the NMR time domain and frequency domain data was modeled using multivariate data analysis techniques. The variation in the NMR spectra that was not correlated with the kappa number was removed using a new preprocessing tool, orthogonal signal correction (OSC). The resulting OSC-treated NMR spectra were used as descriptors to generate partial least-squares projections to latent structures (PLS) models for the variation of the kappa number. PLS weights were used to generate NMR sub-spectra which correspond to changes in the pulps that occur as the pulping process proceeds from high to low values of the kappa number. The sub-spectra were used to gain insight into the changes in the pulps occurring at the molecular level. Concomitant changes in cellulose crystallinity and the amounts of hemicellulose and lignin were observed in these sub-spectra. Copyright © 2001 John Wiley & Sons, Ltd.

  • 14.
    Hedenström, Mattias
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wiklund, Susanne
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sundberg, Björn
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Visualization and interpretation of OPLS models based on 2D NMR Data2008In: Chemometrics and Intelligent Laboratory Systems, ISSN 0169-7439, E-ISSN 1873-3239, Vol. 92, no 2, p. 110-117Article in journal (Refereed)
    Abstract [en]

    Multivariate analysis on spectroscopic 1H NMR data is well established in metabolomics and other fields where the composition of complex samples is studied. However, biomarker identification can be hampered by overlapping resonances. 2D NMR data provides a more detailed “fingerprint” of the chemical structure and composition of the sample with greatly improved spectral resolution compared to 1H NMR data. In this report, we demonstrate a procedure for the construction of multivariate models based on frequency domain 2D NMR data where the loadings can be visualized as highly informative 2D loading spectra. This method is based on the analysis of raw spectral data without any need for peak picking or integration prior to analysis. Spectral features such as line widths and peak positions are thus retained. Hence, the loadings can be visualized and interpreted on a molecular level as pseudo 2D spectra in order to identify potential biomarkers. To demonstrate this strategy we have analyzed HSQC spectra acquired from populus phloem plant extracts originating from a set of designed experiments with OPLS regression.

  • 15.
    Nilsson, David
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pine and spruce roundwood species classification using multivariate image analysis on bark2005In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 59, no 6, p. 689-695Article in journal (Refereed)
    Abstract [en]

    Wood discs from 67 pine and 79 spruce logs were collected from a forest clearing. Three different 24-bit red-green-blue (RGB) images were acquired from the radial surface of each disc. The first image contained bark, the second image was a mixture of bark and wood surface, and the third image consisted only of wood surface. The image texture was compressed into vectors of Fourier-transformed wavelet coefficients. These were assembled in matrices and analysed by principal component analysis (PCA) and partial least-squares projections to latent structures (PLS). Classification using Fourier-transformed wavelet scales showed that the wood species could be predicted with 90% accuracy. A thorough examination of this classification showed that the predicting power of these models was mostly due to wavelet scales that represented the mean value of each colour channel. The prediction accuracy that could be obtained from coefficients representing image texture was generally low. The use of grey-level co-occurrence matrices prior to the wavelet transformation showed, however, that it is possible to classify the wood species of pine and spruce with an accuracy approaching 100%.

  • 16.
    Nilsson, David
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Elg-Christofferson, Kristina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjöström, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Agnemo, Roland
    The effect of designed wood storage on the brightness of bleached and unbleached thermo mechanical pulp2003In: Nordic Pulp & Paper Research Journal, Vol. 18, no 4, p. 369-76Article in journal (Refereed)
    Abstract [en]

    60 Norway Spruce (Picea abies) logs were stored in climate chambers for 14 weeks in order to investigate the effect of wood storage on the brightness of thermo mechanical pulp. The storage conditions were altered according to an experimental design comprised of five factors; light, watering, temperature, tree growth and debarking. Wood samples were collected during the storage period and refined into thermo mechanical pulp. ISO brightness values were measured for the unbleached, the dithionite bleached and the hydrogen peroxide bleached thermo mechanical pulp samples that were refined from the stored wood. The decrease in ISO brightness after 14 weeks of wood storage was significant for some of the samples bleached with dithionite. It was found that the interaction between watering and light had a significant negative effect on the brightness of the unbleached and dithionite bleached samples. The samples bleached with hydrogen peroxide generally showed a more consistent ISO brightness. Only watering and temperature had a significant effect on the brightness of peroxide bleached thermo, mechanical pulp.

  • 17.
    Nilsson, David
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjöström, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Agnemo, Roland
    Prediction of thermo mechanical pulp brightness using NIR spectroscopy on wood raw material2005In: Paperi ja puu, ISSN 0031-1243, Vol. 87, no 2, p. 102-109Article in journal (Refereed)
    Abstract [en]

    Partial Least Squares regression to latent structures was used to find a correlation between near-infrared reflectance spectra of samples of milled Norway Spruce (Picea abies) and ISO brightness of bleached thermo mechanical pulp. Logs of spruce were stored in climate chambers with different conditions for 14 weeks. A factorial design based on five variables was constructed to control the storage and to provide different brightness properties of the stored spruce logs. Wood samples were collected during the storage and they were analysed with near-infrared reflectance spectroscopy and later refined to thermo mechanical pulp. The pulp was bleached with both hydrogen peroxide and sodium dithionite. The ISO brightness of the bleached pulp was correlated to the near-infrared spectra of the untreated samples using Partial Least Squares regression to latent structures. The modelling showed that it is possible to predict the ISO brightness of bleached thermo mechanical pulp from near-infrared spectra of original wood raw material.

  • 18.
    Persson, Per-Axel
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Andersson, Ove
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Soldatov, Alexander
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    High-pressure polymerized C601996In: Extended Abstracts of Carbon´96, European Carbon Conference, Newcastle-upon-Tyne 1996, volume 2, The British Carbon Group , 1996, p. 746-747Conference paper (Other academic)
  • 19.
    Persson, Per-Axel
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fransson, Åke
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Inaba, Akira
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Meingast, Christoph
    Soldatov, Alexander
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Physical properties of pressure polymerized C601996In: High Pressure Science and Technology: Proceedings of the Joint XV AIRAPT and XXXIII EHPRG International Conference, Warsaw 1995, Singapore: World Scientific , 1996, p. 716-718Conference paper (Refereed)
    Abstract [en]

    The properties of C60 have been studied after treatment at high temperature and high pressure (1.1 GPa and 565 K for 2 h). The treated material is insoluble in organic solvents. We present results obtained in NMR and Raman studies and measured data for the specific heat and the thermal expansion. Our results show clearly that there are no covalent bonds and no molecular rotation, but suggest that the molecules are slightly deformed and held together by weak pi-type bonds.

  • 20.
    Persson, Per-Axel
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Soldatov, Alexander
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    NMR and Raman characterization of pressure polymerized C-601996In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 258, no 5-6, p. 540-546Article in journal (Refereed)
    Abstract [en]

    Bulk C60 has been treated at 1.1 GPa and 550–585 K, producing a dense insoluble material which on heating to above 600 K reverts to normal C60. Raman and IR studies on modified material show a large number of new lines, and the Raman pentagon pinch mode shifts from 1469 to 1458 cm−1 as on photopolymerization. MAS NMR shows one broadened line at the original C60 shift 144 ppm and a small peak at about 77 ppm due to the bridging carbons. None of the new resonances observed for C60 polymerized by other methods were observed. The results verify previously suggested polymeric structures where the fullerence cages are connected by four-membered rings.

  • 21. Siedlecka, A
    et al.
    Wiklund, Susanne
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Péronne, M-A
    Micheli, F
    Lesniewska, J
    Sethson, Ingmar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lindberg, Richard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sundberg, B
    Mellerowicz, J. E
    Pectin methyl esterase inhibits intrusive and symplastic cell growth in developing wood of Populus treesManuscript (Other academic)
  • 22. Siedlecka, Anna
    et al.
    Wiklund, Susanne
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Peronne, Marie-Amelie
    Micheli, Fabienne
    Lesniewska, Joanna
    Sethson, Ingmar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Richard, Luc
    Sundberg, Björn
    Mellerowicz, Ewa J
    Pectin methyl esterase inhibits intrusive and symplastic cell growth in developing wood cells of Populus2008In: Plant Physiology, ISSN 0032-0889, Vol. 146, p. 554-65Article in journal (Refereed)
    Abstract [en]

    Wood cells, unlike most other cells in plants, grow by a unique combination of intrusive and symplastic growth. Fibers grow in diameter by diffuse symplastic growth, but they elongate solely by intrusive apical growth penetrating the pectin-rich middle lamella that cements neighboring cells together. In contrast, vessel elements grow in diameter by a combination of intrusive and symplastic growth. We demonstrate that an abundant pectin methyl esterase (PME, EC 3.1.1.11) from wood-forming tissues of hybrid aspen (Populus tremula L. x tremuloides Michx.) acts as a negative regulator of both symplastic and intrusive growth of developing wood cells. When PttPME1expression was up- and down-regulated in transgenic aspen trees, the PME activity in wood-forming tissues was correspondingly altered. PME removes methyl ester groups from homogalacturonan, and the transgenic trees had modified homogalacturonan methylesterification patterns, as demonstrated by two-dimensional NMR and immunostaining using PAM1 and LM7 antibodies. The in situ distributions of PAM1 and LM7 epitopes revealed changes in pectin methylesterification in the transgenic trees that were specifically localized in expanding wood cells. The results show that en-block de-esterification of homogalacturonan by PttPME1 inhibits both symplastic growth and intrusive growth. PttPME1 is therefore involved in mechanisms determining fiber width and length in the wood of aspen trees.

  • 23.
    Soldatov, Alexander
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Persson, Per-Axel
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pressure polymerized C60: Raman and NMR studies1996In: Fullerenes and Fullerene Nanostructures: Proceedings of the International Winterschool on Electronic Properties of Novel Materials, Kirchberg, Tyrol, Austria 1996, Singapore: World Scientific , 1996, p. 344-348Conference paper (Refereed)
    Abstract [en]

    The properties of bulk C60 have been studied after treatment at 1.1 GPa and 550-585 K. The treated material is insoluble in both toluene and 1,2-dichlorobenzene. Raman spectroscopy on modified aterial shows a large number of new lines, and the Raman pentagon pinch mode (Ag2) shifts from 1469 to 1458 /cm as on photopolymerization. MAS NMR shows one broadened line at the original C60 shift 144 ppm and a small peak at about 77 ppm due to the bridging carbons. The results verify previous suggested polymeric structures where the fullerene cages are connected by four-membered rings.

  • 24.
    Sundqvist, Bertil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Andersson, Ove
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fransson, Åke
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Inaba, Akira
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Launois, Pascale
    Meingast, Christoph
    Moret, Roger
    Moritz, Thomas
    Persson, Per-Axel
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Department of Physics.
    Soldatov, Alexander
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Physical properties of pressure polymerized C601996In: Fullerenes: Recent Advances in the Chemistry and Physics of Fullerenes and Related Materials, volume 3: Proceedings of the 189th ECS Meeting, Symposium Fullerenes: Chemistry, Physics, and New Directions VIII, Los Angeles 1996, Pennington, NJ: The Electrochemical Society , 1996, p. 1014-1028Conference paper (Refereed)
    Abstract [en]

    We present in this paper an overview of the physical properties of the high pressure polymerized C60 phase commonly known as "soft fcc". This phase has been studied by several methods over wide ranges in temperature T and/or pressure, p. We present here experimental information about the specific heat capacity, the thermal expansion coefficient, the lattice structure, and the thermal conductivity, and we also show results obtained by NMR and Raman spectroscopy. All data presented agree with the accepted model that the individual molecules in this phase are covalently bound to form linear molecular chains. In particular, the NMR data show clearly the presence of covalent bonds, and the Raman data exhibit several new lines at very low energies connected with chain vibrations. Thermal conductivity data obtained during polymerization show both the time dependence of the process and that polymerization occurs at lower p and T than observed previously for this phase.

  • 25.
    Sundqvist, Bertil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jun, Jan
    Launois, Pascale
    Moret, Roger
    Persson, Per-Axel
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Soldatov, Alexander
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Structural and physical properties of pressure polymerized C601998In: Carbon, vol. 36 issue 5-6: Proceedings of Symposium A: Fullerenes and Carbon Based Materials, of the Joint Meeting of the European Materials Research Society (E-MRS'97) and the International Conference on Advanced Materials (ICAM'97), Strasbourg 1997, Elsevier B.V. , 1998, p. 657-660Conference paper (Refereed)
    Abstract [en]

    We discuss the structural and dynamic properties of C60 polymerized under low-P, low-T conditions, and suggest that the disordered mixed orthorhombic-tetragonal-rhombohedral phases produced under these conditions arise from nucleation of molecular chains in random directions because of the quasi-free molecular rotation under standard reaction conditions in the fcc phase of C60. Polymerization in He gives results qualitatively different from those obtained in other media.

  • 26. Ushakov, Evgeny N
    et al.
    Gromov, Sergey P
    Vedernikov, Artem I
    Malysheva, Ekaterina V
    Botsmanova, Asya A
    Alfimov, Michael V
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Whitesell, James K
    Fox, Marye Anne
    Self-Organization of Highly Stable Electron Donor-Acceptor Complexes via Host-Guest Interactions2002In: The Journal of Physical Chemistry A, Vol. 106, no 10, p. 2020-3Article in journal (Refereed)
    Abstract [en]

    Biscrown stilbene S forms complexes of 1:1 and 2:1 composition with bisammonium viologen salt V4+ in acetonitrile solution. Both of the complexes exhibit spectroscopic behavior typical of molecular electron donor-acceptor complexes. The 1:1 complex [S·V]4+ has a very high thermodynamic stability (log K = 9.08), which is due to simultaneous interaction of the two ammonium groups of V4+ with the two 18-crown-6-ether units of S. The 2:1 complex (log K = 12.28) [S·V·S]4+ likely has a sandwich-type layered structure in which the acceptor salt is located between two complexed molecules of the biscrown stilbene.

  • 27.
    Wiklund, Susanne
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johansson, Erik
    Sjöström, Lina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mellerowicz, Ewa J
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shockcor, John P
    Gottfries, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Moritz, Thomas
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Visualization of GC/TOF-MS-based metabolomics data for identification of biochemically interesting compounds using OPLS class models2008In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 80, no 1, p. 115-22Article in journal (Refereed)
    Abstract [en]

    Metabolomics studies generate increasingly complex data tables, which are hard to summarize and visualize without appropriate tools. The use of chemometrics tools, e.g., principal component analysis (PCA), partial least-squares to latent structures (PLS), and orthogonal PLS (OPLS), is therefore of great importance as these include efficient, validated, and robust methods for modeling information-rich chemical and biological data. Here the S-plot is proposed as a tool for visualization and interpretation of multivariate classification models, e.g., OPLS discriminate analysis, having two or more classes. The S-plot visualizes both the covariance and correlation between the metabolites and the modeled class designation. Thereby the S-plot helps identifying statistically significant and potentially biochemically significant metabolites, based both on contributions to the model and their reliability. An extension of the S-plot, the SUS-plot (shared and unique structure), is applied to compare the outcome of multiple classification models compared to a common reference, e.g., control. The used example is a gas chromatography coupled mass spectroscopy based metabolomics study in plant biology where two different transgenic poplar lines are compared to wild type. By using OPLS, an improved visualization and discrimination of interesting metabolites could be demonstrated.

  • 28.
    Wiklund, Susanne
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Karlsson, Marlene
    Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, SLU, Umeå.
    Antti, Henrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjöström, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wingsle, Gunnar
    Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, SLU, Umeå.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A new metabonomic strategy for analysing the growth process of the poplar tree2005In: Plant Biotechnology Journal, ISSN 1467-7644, E-ISSN 1467-7652, Vol. 3, no 3, p. 353-362Article in journal (Refereed)
    Abstract [en]

    High-resolution, magic angle spinning, proton nuclear magnetic resonance (H-1 HR/MAS NMR) spectroscopy and multivariate data analysis using batch processing (BP) were applied to 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 expressed sequence tag (EST) library of poplar tree (Populus tremula L. x tremuloides Michx.) for metabonomic characterization. The PttMYB76 gene is believed to affect different paths in 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 H-1 HR/MAS NMR spectroscopy. The application of multivariate BP 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 focuses 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 highlight the importance of applying robust and organized multivariate data analysis approaches to facilitate the modelling and interpretation of complex biological data sets.

  • 29.
    Öberg, Kjell
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Berglund, Anders
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Prediction of nonlinear optical responses of organic compounds2001In: Journal of Chemical Information and Modeling, Vol. 41, no 3, p. 811-4Article in journal (Refereed)
    Abstract [en]

    The nonlinear optical quantities, second and third harmonics ( and ), were predicted using a quantitative structure-property relationship (QSPR) approach. Molecular orbital ab initio calculations were applied to generate easily accessible variables to be used in the partial least-squares analysis. Simplified equations are presented that could be used to predict the experimental and responses, prior to further investigations of potentially interesting molecules for use in optical materials.

  • 30.
    Öberg, Kjell
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Seshadri, Kannan
    Allara, David
    Spectroscopic Characterization of the Bonding, Orientation, and Coverage of Copper Tetraazaphthalocyanine Monolayer Films on SiO2 Surfaces2000In: The Journal of Physical Chemistry B, Vol. 104, no 45, p. 10627-34Article in journal (Refereed)
    Abstract [en]

    Self-assembled monolayer films of a metallotetraazaphthalocyanine were prepared using two different reaction conditions. The films were characterized by ellipsometry, AFM, electronic absorption spectroscopy, semiempirical MO calculations, core-level XPS, and projection of a calculated structure of the chromophore onto a surface to obtain its silhouette area for comparison with surface concentration from absorption spectroscopy. A denser packing of the chromophores is found in the SAM film prepared with bromonaphthalene at 250 C as compared with the film from the more polar solvent DMF at 120 C. Data is consistent with an almost vertical orientation of the chromophores in the former film. A different number of bonds connecting the chromophore with the coupling molecule is suggested as an explanation to differences in the absorption bands for the two films.

  • 31.
    Öhman, Lars-Olof
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Aluminum-27 NMR of Solutions2007In: eMagRes, E-ISSN 2055-6101, Vol. 2007Article in journal (Refereed)
1 - 31 of 31
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