miun.sePublications
Change search
Refine search result
3456789 251 - 300 of 450
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 251. Lin, Guoqiang
    et al.
    Hjalmarsson, Mats
    Högberg, Hans-Erik
    Jernstedt, Karen
    Norin, Torbjörn
    Asymmetric Synthesis of 2-alkylalkanoic acids via Alkylation of Chiral Amide Anions.1984In: Acta Chemica Scandinavica, ISSN 0904-213X, E-ISSN 1902-3103, Vol. B38, p. 795-801Article in journal (Refereed)
  • 252. Lin, Guoqiqng
    et al.
    Högberg, Hans-Erik
    Norin, Torbjörn
    Asymmetric Synthesis of 2-Alkylalkanoic Acids via Alkylation of Chiral Amide Anions1984In: Chinese Science Bulletin (Kexue Tongbao -English version), ISSN 1001-6538, Vol. 29, no 5, p. 632-634Article in journal (Refereed)
  • 253. Lin, S
    et al.
    Zhao, G-L
    Deiana, L
    Sun, J
    Zhang, Q
    Leijonmarck, H
    Còrdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Dynamic kinetic asymmetric domino oxa-michael/carbocyclization by combination of transition-metal and amine catalysis: Catalytic enantioselective synthesis of dihydrofurans2010In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, no 47, p. 13930-13934Article in journal (Refereed)
    Abstract [en]

    Into the pot: A one-pot highly chemo- and enantioselective catalytic domino oxa-Michael/carbocyclization between α,β-unsaturated aldehydes and propargylic alcohols is presented. This dynamic kinetic transformation requires a combination of transition-metal and amine catalysis to afford functionalized dihydrofurans in good to high yields and up to 99.5:0.5 e.r.

  • 254.
    Lin, Shuangzheng
    et al.
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, S-10691 Stockholm, Sweden .
    Deiana, Luca
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, S-10691 Stockholm, Sweden .
    Zhao, Gui-Ling
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, S-10691 Stockholm, Sweden .
    Sun, Junliang
    Stockholm Univ, Arrhenius Lab, Berzelii Ctr EXSELENT Porous Mat, S-10691 Stockholm, Sweden .
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Dynamic One-Pot Three-Component Catalytic Asymmetric Transformation by Combination of Hydrogen-Bond-Donating and Amine Catalysts2011In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, no 33, p. 7624-7630Article in journal (Refereed)
    Abstract [en]

    In control: The first dynamic one-pot three-component asymmetric transformation between aldehydes, protected α-cyanoglycine esters, and enals catalyzed by a combination of a simple hydrogen-bond-donating catalyst and a chiral amine catalyst is disclosed. Polysubstituted proline derivatives, which have a quaternary α stereocenter, were synthesized with high endo-, diastereo-, and enantioselectivities (93-99 ee). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 255.
    Lindberg, Emma
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Science Education and Mathematics.
    Digitala läromedel i kemi?: En undersökning av hur de digitala läromedel i kemi för grundskolans senare del som finns på marknaden ser ut.2018Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Samhället har genomgått en förändring från analoga system till digitala.Läromedel som används i skolan behöver följa med i utvecklingen. Syftet meddenna studie är att undersöka hur digitala läromedel i kemi ser ut. Det är även avintresse att ta reda på hur de digitala läromedlen gör för att skapa en bild avämnet kemi som är intresseväckande och intressant samt om dessa digitalaläromedel är utformade för att tillgodose det syfte som presenteras i kursplanenför kemi i grundskolan. Tre olika läromedel, Kemi Direkt från Sanomautbildning, PLUS Kemi från Natur & Kultur och Spektrum Kemi från Liber AB,undersöks med hänsyn till flera olika punkter och aspekter. Undersökningenomfattar hur dessa digitala läromedel presenteras för läsaren, vad det finns förolika möjligheter att ta del av materialet, vilka anpassningar läromedlettillhandahåller för såväl svaga som starka elever, vad det finns för material föratt underlätta planering, laborationer och bedömning. Vidare vad det finns föruppgifter och hur dessa uppgifter rättas eller bedöms, om de olika syftenauppfylls samt hur intressant och förstående är den information som presenterasom växthuseffekten och den förhöjda växthuseffekten. Alla tre läromedel finnssom fysiska böcker som sedan har digitaliserats och på olika sätt anpassats föratt finnas tillgängliga digitalt. Det medför att de inte upplevs som innovativa ochintressanta digitala läromedel även om det såklart inte heller finns stora fel ochbrister. Det framkommer att Spektrum Kemi är det läromedel som uppvisar denstörsta responsen på de undersökta parametrarna. Önskvärt skulle vara ett nyttläromedel som inte är en digitalisering av en tidigare förlaga utan som är skapadför att vara digital och använder tekniken och den digitala världens alla finesseroch möjligheter.

  • 256.
    Lindman, Björn
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Lunds Universitet.
    Medronho, Bruno
    University of Algarve, Faro, Portugal.
    Alves, Luís
    University of Coimbra, Portugal.
    Costa, Carolina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 35, p. 23704-23718Article in journal (Refereed)
    Abstract [en]

    Cellulose is the most abundant polymer and a very important renewable resource. Since cellulose cannot be shaped by melting, a major route for its use for novel materials, new chemical compounds and renewable energy must go via the solution state. Investigations during several decades have led to the identification of several solvents of notably different character. The mechanisms of dissolution in terms of intermolecular interactions have been discussed from early work but, even on fundamental aspects, conflicting and opposite views appear. In view of this, strategies for developing new solvent systems for various applications have remained obscure. There is for example a strong need for using forest products for higher value materials and for environmental and cost reasons to use water-based solvents. Several new water-based solvents have been developed recently but there is no consensus regarding the underlying mechanisms. Here we wish to address the most important mechanisms described in the literature and confront them with experimental observations. A broadened view is helpful for improving the current picture and thus cellulose derivatives and phenomena such as fiber dissolution, swelling, regeneration, plasticization and dispersion are considered. In addition to the matter of hydrogen bonding versus hydrophobic interactions, the role of ionization as well as some applications of new knowledge gained are highlighted.

  • 257.
    Lindmark Henriksson, Marica
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Isaksson, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Vanek, Tomas
    Valterova, Irena
    Sjödin, Kristina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Transformation of terpenes using a Picea abies suspension culture2004In: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 107, no 2, p. 173-184Article in journal (Refereed)
    Abstract [en]

    When subjected to a Picea abies suspension cell culture, beta-pinene, either one of the pure enantiomers or the racemate, was transformed mainly to trans-pinocarveol along with the minor products myrtenol, alpha-terpineol, pinocarvone, myrtenal and cis-pinocarveol. The absolute configuration of the major products corresponded to that of the starting beta-pinene enantiomer. Some of the primary transformation products, i.e. (1S)-cis- and (1S)-trans-pinocarveol, (1R)-myrtenol and (4S)-alpha-terpineol, were also tested as substrates of the P. abies suspension culture. They reacted more slowly than beta-pinene but, except for (4S)-alpha-terpineol, they were all transformed. Thus, (1R)-myrtenol was converted into both (1R)-myrtenal and (1R)-myrtanol, whereas (1S)-trans-pinocarveol was converted into (1S)-pinocarvone. (4R)-Limonene was slowly transformed by the suspension culture into limonene-(1,2)-epoxide as the major product, with carveol, perillyl alcohol and 1,8-cineole as minor products. Autoxidation of terpenes in cell-free nutrient medium was investigated in detail. alpha-Pinene and beta-pinene were both autoxidized to a certain extent, while limonene remained unaffected. The rate of the autoxidation was more than one order of magnitude slower than that of the biotransformation. Moreover, different products were formed by autoxidation than by biotransformation.

  • 258.
    Lindmark-Henriksson, Marica
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Isaksson, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Sjödin, Kristina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Vanek, Tomas
    Valterova, Irena
    Transformation of alpha-pinene using Picea abies suspension culture2003In: Journal of Natural Products, ISSN 0163-3864, Vol. 66, no 3, p. 337-343Article in journal (Refereed)
    Abstract [en]

    alpha-Pinene, both as the pure enantiomers and as the racemate, was transformed mainly to trans-verbenol by treatment with a Picea abies suspension cell culture. These reactions were followed by a slow transformation of the verbenol to verbenone, which was not transformed further. trans-Pinocarveol, myrtenol, cis-verbenol, and alpha-terpineol were byproducts of intermediate abundance. When subjected to the action of the suspension culture, cis-verbenol was not only transformed to verbenone but also isomerized to trans-verbenol. The transformation of alpha-pinene was fast, and the products were detected within one minute. The absolute configuration of the major products corresponded to that of the starting alpha-pinene enantiomer

  • 259. Lindström, M
    et al.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, H E
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Synthesis of nucleoside analogs: Meeting abstract2003In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 2003Conference paper (Refereed)
  • 260. Lindström, M
    et al.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Servi, S
    Pedrocchi-Fantoni, G
    Preparation of enantiomerically pure methyl (R)-a-hydroxy(2-furyl)acetate by Baker's yeast reduction in multiphase systems1999In: Acta Chemica Scandinavica, ISSN 0904-213X, Vol. 53, no 5, p. 378-380Article in journal (Refereed)
  • 261. Lindström, Mona
    et al.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Bouilly, S
    Velonia, K
    Smonou, I
    Synthesis of diastereo- and enantiomerically pure anti-3-methyl-1,4-pentanediol via lipase catalysed acylation: Tetrahedron: Asymmetry2005In: Tetrahedron: Asymmetry, ISSN 0957-4166, Vol. 16, no 7, p. 1355-1360Article in journal (Refereed)
    Abstract [en]

    Racemic trans-4,5-dimethylhydrofuran-2(3H)-one was synthesised from 5-methyl-furan-2(3H)-one, (alpha-angelica lactone). The key reaction in the synthesis was the 1,4-conjugate addition of an organocuprate to 5-methylfuran-2(5H)-one (beta-angelica lactone). Different types of organocuprates were tested with the highest anti:syn ratio of 99.4:0.6 being obtained by the use of a Gilman organocuprate reagent. The enantioselective acylation of racemic 3-methyl-pentan-1,4-diol, catalysed by a variety of lipases in organic media, was investigated. The highest enantioselectivity (E > 400) was obtained when Novozyme 435 was used as the catalyst at a water activity of a(w) similar to 0. Thus, both enantiomers, (3S,4R)- and (3R,4S)-3-methyl-pentan-1,4-diol, were obtained in very high diastereomeric (> 99% de) and enantiomeric purities (> 99.8% and > 97.4% ee, respectively).

  • 262.
    Liu, Rong
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Berglund, Per
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Preparation of the four stereoisomers of 3-bromo-2-butanol or their acetates via lipase-catalysed resolutions of the racemates derived from dl- or meso-2,3-butanediol2005In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 16, no 15, p. 2607-2611Article in journal (Refereed)
    Abstract [en]

    The four stereoisomeric 3-bromo-2-butanols and/or their acetates were prepared via lipase-catalysed kinetic resolution by hydrolyses of the acetates of the (+/-)-syn- and (+/-)-anti-3-bromo-2-butanols, or via esterifications of the alc hols. The diastereomeric bromoacetates were obtained by syntheses from the dl- and meso-2,3-butanediols, respectively. On a preparative scale, the four stereoisomers, either as the free alcohols or as their acetates, were obtained in > 95% ee, and in 35-40% yield (based on the starting racemates).

  • 263.
    Liu, Rong
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Chemoenzymatic preparation of (2S, 3S)- and (2R, 3R)-2,3-butanediols and their esters from mixtures of d,l- and meso-diols2001In: Tetrahedron: Asymmetry, ISSN 0957-4166, Vol. 12, no 5, p. 771-778Article in journal (Refereed)
    Abstract [en]

    An efficient method of preparing the pure enantiomers of 2,3-butanediol front commercially available mixtures of the d,l- and meso-isomers was developed. It furnished (2S,3S)-2.3-butanediol with > 99% e.e. and a >9.5/0.5 diastereomeric ratio and (2R,3R)-2,3-butanediol in 95% e.e. and >9.5/<5 diastereomeric ratio.

  • 264. Liénard, Marjorie A
    et al.
    Strandh, Maria
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Johansson, Tomas
    Löfstedt, Christer
    Key biosynthetic gene subfamily recruited for pheromone production prior to the extensive radiation of Lepidoptera2008In: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 8, no 270Article in journal (Refereed)
    Abstract [en]

    Background Moths have evolved highly successful mating systems, relying on species-specific mixtures of sex pheromone components for long-distance mate communication. Acyl-CoA desaturases are key enzymes in the biosynthesis of these compounds and to a large extent they account for the great diversity of pheromone structures in Lepidoptera. A novel desaturase gene subfamily that displays Δ11 catalytic activities has been highlighted to account for most of the unique pheromone signatures of the taxonomically advanced ditrysian species. To assess the mechanisms driving pheromone evolution, information is needed about the signalling machinery of primitive moths. The currant shoot borer, Lampronia capitella, is the sole reported primitive non-ditrysian moth known to use unsaturated fatty-acid derivatives as sex-pheromone. By combining biochemical and molecular approaches we elucidated the biosynthesis paths of its main pheromone component, the (Z,Z)-9,11-tetradecadien-1-ol and bring new insights into the time point of the recruitment of the key Δ11-desaturase gene subfamily in moth pheromone biosynthesis. Results The reconstructed evolutionary tree of desaturases evidenced two ditrysian-specific lineages (the Δ11 and Δ9 (18C>16C)) to have orthologs in the primitive moth L. capitella despite being absent in Diptera and other insect genomes. Four acyl-CoA desaturase cDNAs were isolated from the pheromone gland, three of which are related to Δ9-desaturases whereas the fourth cDNA clusters with Δ11-desaturases. We demonstrated that this transcript (Lca-KPVQ) exclusively accounts for both steps of desaturation involved in pheromone biosynthesis. This enzyme possesses a Z11-desaturase activity that allows transforming the palmitate precursor (C16:0) into (Z)-11-hexadecenoic acid and the (Z)-9-tetradecenoic acid into the conjugated intermediate (Z,Z)-9,11-tetradecadienoic acid. Conclusion The involvement of a single Z11-desaturase in pheromone biosynthesis of a non-ditrysian moth species, supports that the duplication event leading to the origin of the Lepidoptera-specific Δ11-desaturase gene subfamily took place before radiation of ditrysian moths and their divergence from other heteroneuran lineages. Our findings uncover that this novel class of enzymes affords complex combinations of unique unsaturated fatty acyl-moieties of variable chain-lengths, regio- and stereo-specificities since early in moth history and contributes a notable innovation in the early evolution of moth-pheromones.

  • 265.
    Ljunggren, Joel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Some Approaches to Eco-Friendly Products from Natural Matrices2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Since the onset of the industrial and chemical revolution, humans have caused immense damages to the surrounding flora and fauna. Effective methods for wood protection measures proved to be toxic; fossil fuels contribute to global warming and pesticides can be detected in the air, water, and soil. It is abundantly clear that efforts to find eco-friendly products are needed, while simultaneously providing the necessary incentives for sustainable worldwide development. Using renewable resources play a critical role in this shift towards circular economies.

    Wood has long been used as a renewable resource in high demand, but its susceptibility to attack by wood-decaying fungi mean that most European woods need to be protected against these fungi before outdoor use. We showed that fractionating turpentine, a pulp and paper mill by-product, increased antifungal efficacy by concentrating bioactive oxygenated sesquiterpenes. Based on this result, recombinations of the fractions were shown to exhibit synergistic effects that enable a more efficient product utilisation. In addition, this approach enabled putative identifications of previously unknown Picea abies turpentine constituents present at low levels.

    For a carbon-neutral society, production of biofuels using oleaginous yeast to convert lignocellulosic biomass into fuel has been hailed as a next-generation source of bioenergy. However, lignocellulose biofuel production by microorganisms is not straightforward and one challenge is the formation of microbe-toxic monomers, such as vanillin, during lignin degradation. The oleaginous yeast Cystobasidium laryngis and other potential oil-producing yeasts were screened for their viability and vanillin biotransformation capabilities. To this end, a mass chromatographic peak extraction tool termed TMATE was developed. Vanillyl alcohol was found to be the main product following vanillin degradation.

    The detrimental health and ecological effects of pesticides highlight the urgency for alternative crop protection measures, such as biological insect control and semiochemicals. In this regard, we present an essential step towards understanding the varied chemical ecology of microbe-insect interactions. Our methodology and findings provide cues with high information value that can be used to develop well-informed and potentially sustainable pest management regimes by, for example, the push-pull methodology using live yeasts.

  • 266.
    Ljunggren, Joel
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Jonsson, Bengt-Gunnar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Edman, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Antifungal efficiency of individual compounds and evaluation of non-linear effects by recombining fractionated turpentine2020In: Microchemical journal (Print), ISSN 0026-265X, E-ISSN 1095-9149, Vol. 153, article id 104325Article in journal (Refereed)
    Abstract [en]

    A combination between a reductive and a holistic assay was employed to investigate whole fraction, synergistic, antagonistic and individual compound efficacy of vacuumdistilled turpentine fractions against the economically important brown-rot fungus Coniophora puteana. The fungus was subjected to recombinations of turpentine fractions at a concentration of 1000 ppm. All combinations exhibited useful antifungal properties, but some antifungal mixtures showed a more pronounced effect than the expected level of inhibition. Synergistic effects by a two-fold factor and minor antagonistic effects were observed. Complete growth inhibition of C. puteana was observed by a fraction obtained after distilling 1 L turpentine at 111–177°C (0.5 mbar) as well as by mixing it with another fraction withdrawn at 70–79°C (0.5 mbar). Chemical compositions of distilled fractions were determined through GC–MS analysis and Orthogonal Partial Least Squares (OPLS) multivariate data analysis of GC–MS chromatograms was employed to zoom in on the most active compounds responsible for antifungal activity. Isomers of epicubenol, the hydrocarbon aromatic compound ar-himachalene and α-cadinol are suggested as effective antifungal compounds. In addition, a subsequent fractionation of the most effective fraction was performed with preparatory gas chromatography and subfractions showed similar or better efficacy than previously observed. Our work demonstrates the possibility to retain adequate synergistic antifungal efficiency and offers an opportunity to explore the effects of individual compounds originating from the same crude sample.

  • 267.
    Lundgren, Anders
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Internal catalytic bed in a staged fluidized bed2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this work the purpose is to investigate whether a staged fluidized bed can maintain its hydrodynamics while introducing a stationary internal catalytic bed in the upper fluidized bed. To accomplish this a literature study has been made. This resulted in finding the key parameters of gas and bed material mass flow that determines if a fluidized bed is formed or not. The literature study also showed a positive catalytic effect with decreased size of the catalytic particles. The experimental setup was designed to check for the two anomalies where the gasifying velocity and the bed material mass flow rate was as high and low as possible. A middle ground was used as another point of interest. The objective was then to incrementally minimize the particle size of the internal catalytic bed. The results showed that the internal catalytic bed could be present in the staged fluidized bed while maintaining the fluid dynamics, but only if the gas velocity was high enough. The produced syngas with the catalytic bed present did not show any results that indicates if the effect was positive or not.

  • 268. Lundh, Mårten
    et al.
    Nordin, Ove
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Enzyme Catalysed Irreversible Transesterifications with Vinyl Acetate: Are they really Irreversible?1995In: Tetrahedron: Asymmetry, ISSN 0957-4166, Vol. 6, no 9, p. 2237-2244Article in journal (Refereed)
  • 269. Lundh, Mårten
    et al.
    Smitt, Olof
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Sex Pheromone of Pine Sawflies: Enantioselective Lipase Catalysed Transesterification of erythro-3,7-Dimethylpentadecan-2-ol, Diprionol1996In: Tetrahedron: Asymmetry, ISSN 0957-4166, Vol. 7, no 11, p. 3277-3284Article in journal (Refereed)
  • 270.
    Lundström, Ulla
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Bain, DC
    Taylor, AF
    Van Hees, PA
    Geibe, Christine E
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Holmström, Sara J
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Melkerud, PA
    Finlay, R
    Jones, DL
    Nyberg, L
    Gustafsson, JP
    Riise, G
    Tau Strand, L
    Effects of acidification and its mitigation with lime and wood ash on forest soil processes in southern Sweden: A Joint Multidisciplinary Study2003In: Water , Air and Soil Pollution: Focus, ISSN 1567-7230, Vol. 3, no 4, p. 167-188Article in journal (Refereed)
  • 271.
    Lundström, Ulla
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Bain, D.C.
    Taylor, A.F.S.
    Van Hees, P.A.W.
    Effects of acidifiaction and its mitigation with lime and wood ash on forest soil processes: a review2003In: Water, Air, & Soil Pollution: Focus, ISSN 1567-7230, Vol. 3, no 4, p. 5-28Article in journal (Refereed)
  • 272.
    Lundström, Ulla S
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Norström, Sara H
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Vestin, Jenny L K
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Essén, Sofia A
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Dissolved Organic Matter Dynamics of Soil and Stream Water in a Catchment Area, Keynote speaker2006Conference paper (Other scientific)
  • 273.
    Lundström, Ulla
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    van Breemen, N.
    Bain, D. C.
    The podzolization process. A reveiw.2000In: Geoderma, ISSN 0016-7061, Vol. 94, no 2-4, p. 91-107Article, review/survey (Refereed)
    Abstract [en]

    This paper reviews the major mechanisms proposed to explain podzolization. These include the production of organic acids that form soluble complexes with aluminium/iron thereby enhancing weathering, followed by illuviation by precipitation/adsorption processes occurring at greater depth. Precipitation of aluminium and iron is explained by decreasing solubility of increasingly metal-rich complexes, or by microbial degradation of the organic ligand. We also discuss proposed role of inorganic hydroxy-aluminium-silicate sols in podzolization. The paper is introductory to a multidisciplinary study of podzolization performed in the Nordic Countries presented in this volume.

  • 274.
    Lundström, Ulla
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    van Breemen, N.
    Bain, D. C.
    van Hees, P. A. W.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Gielser, R.
    Gustafsson, J. P.
    Ilvesniemi, H.
    Karltun, E
    Melkerud, P. A.
    Olsson, M.
    Riise, G.
    Wahlberg, O.
    Bergelin, A.
    Bishop, K.
    Finlay, R.
    Advances in understanding the podzolization process resulting from a multidisciplinary study of three coniferous forest soils in the Nordic Countries2000In: Geoderma, ISSN 0016-7061, Vol. 94, no 2-4, p. 335-353Article in journal (Refereed)
  • 275. Lyytikäinen-Saarenmaa, P
    et al.
    Anderbrant, O
    Löfqvist, J
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Monitoring European pine sawfly population density with pheromone traps in young pine plantations1999In: Forest Ecology and Management, ISSN 0378-1127, Vol. 124, no 2-3, p. 113-121Article in journal (Refereed)
  • 276. Lyytikäinen-Saarenmaa, P
    et al.
    Varama, M
    Anderbrant, O
    Kukkola, M
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Predicting Pine Sawfly Population Densities and Subsequent Defolation with Pheromone Traps2001In: Integrated management and dynamics of forest defoliating insects, 2001, p. 108-116Conference paper (Refereed)
  • 277. Lyytikäinen-Saarenmaa, P.
    et al.
    Varama, M.
    Anderbrant, O.
    Kukkola, M.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Predicting pine sawfly population densities and subsequent defoliation with pheromone traps2001In: Proceedings. Integrated management and dynamics of forest defoliating insects, Victoria, Canada, 15-19 August 1999, 2001, p. 108-116Conference paper (Refereed)
  • 278.
    Lyytikäinen-Saarenmaa, P
    et al.
    Department of Applied Biology, University of Helsinki, Helsinki, Finland.
    Varama, M
    Finnish Forest Research Institute, Vantaa Research Centre, Vantaa, Finland.
    Anderbrant, O
    Department of Ecology, Lund University, Ecology Building, Lund.
    Kukkola, M
    Finnish Forest Research Institute, Vantaa Research Centre, Vantaa, Finland.
    Kokkonen, A.-M.
    Finnish Forest Research Institute, Vantaa Research Centre, Vantaa, Finland.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Monitoring the European pine sawfly with pheromone traps in maturing Scots pine stands2006In: Agricultural and Forest Entomology, ISSN 1461-9555, Vol. 8, no 1, p. 7-15Article in journal (Refereed)
    Abstract [en]

    1. During 1989-93, field studies were conducted in Finland to develop a method based on pheromone traps to monitor and forecast population levels of the European pine sawfly (Neodiprion sertifer Geoffr.) and tree defoliation. 2. Three traps per site were baited with 100 μg of the N. sertifer sex pheromone, the acetate ester of (2S,3S,7S)-3,7-dimethyl-2-pentadecanol (diprionol), in maturing pine stands in southern and central Finland. In addition, three different dosages (1, 10 and 100 μg) of the pheromone were tested in 1991-92. 3. The highest number of males was observed in traps baited with the highest dose. On average, there was a 10-fold increase in trap catch between lure doses. 4. Density of overwintering eggs was used to evaluate the effectiveness of pheromone traps in predicting sawfly populations. The proportion of healthy overwintering eggs was determined each year. A model based on the number of current shoots on sample trees, diameter at breast height and tree height was formulated to estimate eggs per hectare. 5. Linear regression analysis produced high coefficients of determination between number of males in traps and density of total eggs in the subsequent generation, when populations were at peak densities. The relationships were not significant for low population densities. The results indicate a risk of moderate defoliation when the seasonal trap catch is 800-1000 males per trap or higher.

  • 279.
    M, Yu
    et al.
    Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, United States.
    Ibrahem, Ismail
    Boston Coll, Merkert Chem Ctr, Dept Chem, Chestnut Hill, MA 02467 USA.
    Hasegawa, M
    Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, United States.
    Schrock, R.
    Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
    Hoveyda, H
    Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, United States.
    Enol Ethers as Substrates for Efficient Z- and Enantioselective Ring-Opening/Cross-Metathesis Reactions Promoted by Stereogenic-at-Mo Complexes; Utility in Chemical Synthesis and Mechanistic Attributes2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 5, p. 2788-2799Article in journal (Refereed)
    Abstract [en]

    The first examples of catalytic enantioselective ring-opening/cross- metathesis (EROCM) reactions that involve enol ethers are reported. Specifically, we demonstrate that catalytic EROCM of several oxa-and azabicycles, cyclobutenes and a cyclopropene with an alkyl-or aryl-substituted enol ether proceed readily in the presence of a stereogenic-at-Mo monopyrrolide-monoaryloxide. In some instances, as little as 0.15 mol % of the catalytically active alkylidene is sufficient to promote complete conversion within 10 min. The desired products are formed in up to 90% yield and >99:1 enantiomeric ratio (er) with the disubstituted enol ether generated in >90% Z selectivity. The enol ether of the enantiomerically enriched products can be easily differentiated from the terminal alkene through a number of functionalization procedures that lead to the formation of useful intermediates for chemical synthesis (e.g., efficient acid hydrolysis to afford the enantiomerically enriched carboxaldehyde). In certain cases, enantioselectivity is strongly dependent on enol ether concentration: larger equivalents of the cross partner leads to the formation of products of high enantiomeric purity (versus near racemic products with one equivalent). The length of reaction time can be critical to product enantiomeric purity; high enantioselectivity in reactions that proceed to >98% conversion in as brief a reaction time as 30 s can be nearly entirely eroded within 30 min. Mechanistic rationale that accounts for the above characteristics of the catalytic process is provided. © 2012 American Chemical Society.

  • 280.
    Ma, Guangning
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Deiana, L.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Sweden .
    Palo-Nieto, C.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Sweden .
    Liu, L.
    Berzelii Center EXSELENT, Stockholm University, Sweden .
    Sun, J.
    Berzelii Center EXSELENT, Stockholm University, Sweden .
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    A palladium/chiral amine co-catalyzed enantioselective dynamic cascade reaction: Synthesis of polysubstituted carbocycles with a quaternary carbon stereocenter2013In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 52, no 23, p. 6050-6054Article in journal (Refereed)
    Abstract [en]

    Polysubstituted 5- and 6-membered carbocycles were synthesized by the title reaction. The one-pot dynamic relay process generates four new stereocenters, including a quaternary carbon center, in a highly enantioselective fashion (99.5:0.5→99:0.5 e.r.) by using a simple combination of palladium and chiral amine co-catalysts. 

  • 281.
    Ma, Guangning
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Bartoszewicz, Agnieszka
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, SE-10691 Stockholm, Sweden .
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Highly Enantioselective Co-Catalytic Direct Aldol reactions by Combination of Hydrogen-Bond Donating and Acyclic Amino Acid Catalysts2011In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 353, no 17, p. 3114-3122Article in journal (Refereed)
    Abstract [en]

    Highly enantioselective co-catalytic direct aldol reactions by a combination of simple hydrophobic acyclic amino acid and hydrogen-bond donating catalysts are presented. The corresponding aldol products are formed in high yields with high regio-, diastereo- (anti or syn) and enantioselectivity (up to 99.5:0.5 er). The catalyst loadings can be decreased to as little as 2 mol%.

  • 282.
    Ma, Guangning
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Lin, Shuangzheng
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, S-10691 Stockholm, Sweden .
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Kubik, Grzegorz
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, S-10691 Stockholm, Sweden .
    Liu, Leifeng
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, S-10691 Stockholm, Sweden.
    Sun, Junliang
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, S-10691 Stockholm, Sweden.
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Achiral Co-Catalyst Induced Switches in Catalytic Asymmetric Reactions on Racemic Mixtures (RRM): From Stereodivergent RRM to Stereoconvergent Deracemization by Combination of Hydrogen Bond Donating and Chiral Amine Catalysts2012In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 354, no 14-15, p. 2865-2872Article in journal (Refereed)
    Abstract [en]

    A stereochemical divergent approach for the highly enantioselective synthesis of distinct bicyclic products with multiple stereocenters from a racemate using a single chiral catalyst is disclosed. It is based on switches of the overall reaction pathways in the chiral amine-catalyzed cascade reactions between racemic ?-nitro ketones and a,beta-unsaturated aldehydes using different achiral co-catalysts. The utility of the method is exemplified by the highly diasteroselective switch and stereoconvergent deracemization process by combination of chiral amine and achiral hydrogen-bond-donating catalysts.

  • 283. MacDonald, J.C.
    et al.
    Jonsson, Anders
    Högskolan i Östersund.
    Ethyl nitrite: The in vivo synthesis of a mutagenic substance from tobacco smoke and ethanol1981In: Acta Chemica Scandinavica, ISSN 0904-213X, Vol. 335, p. 485-487Article in journal (Refereed)
  • 284. Marques, Eduardo F.
    et al.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    La Mesa, Camilo
    Khan, Ali
    Liquid Crystals and Phase Equilibria Binary Bile Salt-Water Systems2000In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 16, no 11, p. 5178-5186Article in journal (Refereed)
    Abstract [en]

    The phase behavior of several binary sodium bile salt-water systems is investigated over the entire concentration range, with emphasis on concentrated regions beyond the isotropic solution phase. The studied bile acid salts comprise the free salt sodium deoxycholate (SDC), the taurine conjugates sodium taurocholate (STC), sodium taurodeoxycholate (STDC), and sodium taurochenodeoxycholate (STCDC) and the glycine conjugate sodium glycodeoxycholate (SGDC). A combination of classical techniques is used, including phase diagram determination, polarizing microscopy, 2H NMR, and small-angle X-ray scattering (SAXS). The aggregation behavior in the isotropic micellar solutions of STC and STDC is also investigated by pulsed-field gradient NMR self-diffusion. The optical textures and the data from SAXS and 2H NMR clearly point to the formation of hexagonal liquid crystals, possibly of the reverse type, beyond the micellar solution for all the bile salts. Several unusual kinetic effects, such as very slow equilibration times and the formation of transient spherulitic crystals in biphasic regions, are observed. The phase diagrams and structural data are qualitatively discussed in terms of the molecular structure and solubility of the different salts. The formation of lyotropic liquid crystals by bile salts, which has remained unknown for decades, is clearly demonstrated in this work.

  • 285. Marques, Eduardo
    et al.
    Regev, Oren
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Khan, Ali
    Micelles, Dispersions and Liquid Crystals in the Catanionic Mixture Bile Salt-Double-Chained Surfactant. The Bile Salt-Rich Area2000In: Langmuir, ISSN 0743-7463, Vol. 16, no 22, p. 8255-8262Article in journal (Refereed)
    Abstract [en]

    The phase behavior and phase structure for the catanionic pair sodium taurodeoxycholate - didodecyl-dimethylammonium bromide (DDAB) are investigated, at 25 degreesC. A combination of techniques is used including light and electron microscopy, small-angle X-ray scattering, and pulsed field gradient NMR self-diffusion. The bile salt micellar solution incorporates large amounts of the double-chained amphiphile, with the solution region extending to equimolarity. On the contrary, the hexagonal liquid-crystalline phase is destabilized by the addition of small amounts of DDAB. At equimolarity, coacervation instead of precipitation is observed, with formation of a viscous isotropic solution and a very dilute one. In the water-rich part of the phase diagram, a peculiar type of phase separation occurs, involving the formation of very fine bluish dispersions and a region of coexistence of two dispersions (double dispersion region). Microscopy and self-diffusion data for the solution region indicate limited growth of the mixed micelles. Large domains in which the micellar structure appears to be maintained are imaged in the bluish dispersions by electron microscopy. No other type of aggregate such as vesicles or precipitates is observed in the dilute bile salt-rich area of this mixture.

  • 286. Martini, A.
    et al.
    Baldassari, N.
    Baronio, P.
    Anderbrant, O.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Högberg, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Rocchetta, G.
    Mating disruption of the pine sawfly Neodiprion sertifer (Hymenoptera. Diprionidae) in isolated pine stands2002In: Agricultural and Forest Enthomology, ISSN 1461-9555, Vol. 4, no 3, p. 195-201Article in journal (Refereed)
    Abstract [en]

    1. Previous applications of the mating disruption technique to Neodiprion sertifer resulted in decreased numbers of males caught in the treated area but no effect on sex ratio or overall population density. 2. The present study assessed the efficacy of mating disruption against N. sertifer outbreaks in pine stands surrounded by agricultural areas or pasture, and therefore isolated from other infested areas. 3. Pine stands were treated by placing dispensers with an erythro-mixture of the acetate ester of 3,7-dimethyl-2-pentadecanol every 10 m in a grid. 4. The efficacy of this technique was evaluated by comparing the number of males caught in sticky traps baited with synthetic pheromone, and by comparing the sex ratio and the population density of the sawfly in the subsequent generation between treated and control pine stands. 5. The number of males caught within treated areas was significantly lower than in the control area. 6. In the treated pine stands 46% of the egg clusters resulted in male cocoons only, compared to 3% of the clusters in the control stand. 7. A significant reduction of the sawfly population was observed in the treated pine stands. The results contrast to the earlier mating disruption attempts with N. sertifer and can probably be ascribed to the isolation of the experimental stands.

  • 287.
    Medronho, Bruno
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. University of Algarve, Faro, Portugal.
    Filipe, Alexandra
    University of Algarve, Faro, Portugal.
    Napso, Sofia
    Technion-Israel Institute of Technology, Haifa, Israel.
    Khalfin, Rafail L.
    Technion-Israel Institute of Technology, Haifa, Israel.
    Pereira, Rui F. P.
    University of Minho, Braga, Portugal.
    De Zea Bermudez, Verónica
    University of Trás-os-Montes e Alto Douro, Vila Real, Portugal.
    Romano, Anabela
    University of Algarve, Faro, Portugal.
    Cohen, Yachin
    Technion-Israel Institute of Technology, Haifa, Israel.
    Silk Fibroin Dissolution in Tetrabutylammonium Hydroxide Aqueous Solution2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, p. 4107-4116Article in journal (Refereed)
    Abstract [en]

    Bombyx mori L. silk fibroin (SF) is widely used in different areas due to its ability to form durable and resilient materials with notable mechanical properties. However, in some of these applications the dissolution of SF is required, and this is not often straightforward due to its inability to be dissolved in the majority of common solvents. This work reports a novel approach to dissolve SF using 40 wt % aqueous tetrabutylammonium hydroxide, TBAOH(aq), at mild temperature. A thorough rheological study combined with small-angle X-ray scattering is presented to correlate the SF state in solution with changes in the rheological parameters. The scattering data suggest that the SF conformation in TBAOH(aq) is close to a random coil, possibly having some compact domains linked with flexible random chains. The radius of gyration (Rg) and the molecular weight (Mw) were estimated to be ca. 17.5 nm and 450 kDa, respectively, which are in good agreement with previous works. Nevertheless, a lower Mw value was deduced from rheometry (i.e., 321 kDa) demonstrating a low degree of depolymerization during dissolution in comparison to other harsh processes. The transition from a dilute to a semidilute regime coincides with the estimated critical concentration and is marked by the presence of a shear-thinning behavior in the flow curves, violation of the empirical Cox-Merz rule, and an upward increase in the activation energy. This work paves the way toward the development of advanced high-tech SF-based materials. © 2019 American Chemical Society.

  • 288. Moberg, M
    et al.
    Nilsson, E
    Holmström, Sara J. M.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla S
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Pettersson, J
    Markidies, K
    Fingerprinting siderophores by the exchange of iron by gallium and subsequent column- switched LC-ICP-MS.2003In: 16th IMSC (The International Mass Spectrometry Society);Edinburgh, Scotland, 2003-08-31 - 2003-09-05, 2003Conference paper (Other academic)
  • 289. Moberg, M.
    et al.
    Nilsson, E. M.
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Pettersson, J.
    Markides, K.
    Fingerprinting metal-containing biomolecules after reductive displacement of iron by gallium and subsequent column-switched LC-ICP-MS analysis applied on siderophore.2004In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 76, no 9, p. 2618-2622Article in journal (Refereed)
    Abstract [en]

    Column-switching liquid chromatography followed by lowresolution ICPMS was evaluated as a tool for speciation analysis of metal-containing biomolecules. The strategy was applied on siderophores, strong iron chelators of low molecular weight (M-w < 1500). Prior to the LC-ICPMS analysis, reductive displacement of iron by gallium was performed using ascorbate as the reducing agent to increase the sensitivity. Different experimental conditions during the exchange reaction were tested using ferrichrysin and ferrichrome for evaluation. A reaction time of 30 min and a pH of 3.9 gave an exchange yield of 27 and 83% for ferrichrysin and ferrichrome, respectively. A gradient elution profile was also developed to separate gallium-chelated siderophores on a PGC column. Detection limits for standard solutions of ferrichrysin and ferrichrome in the low-nanomolar range were obtained by monitoring the gallium-69 isotope. The combined use of LC-ICPMS and LC-ESI-MS/MS was also evaluated as a tool to identify unknown metal complexes, here siderophores, in field soil solution samples.

  • 290.
    Moberg, My
    et al.
    Uppsala University.
    Bergquist, Jonas
    Uppsala University.
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    A generic stepwise optimization strategy for liquid chromatography electrospray ionization tandem mass spectrometry methods2006In: Journal of Mass Spectrometry, ISSN 1076-5174, E-ISSN 1096-9888, Vol. 41, no 10, p. 1334-1345Article in journal (Refereed)
    Abstract [en]

    The feasibility and advantages of using sophisticated chemometric tools in combination with the execution of thoroughly planned experiments to determine experimental conditions for optimal performance of an LC-ESI-MS/MS analysis is demonstrated. A stepwise strategy is proposed, which provides a controlled optimization procedure of the chromatographic quality (in terms of separation among the sample constituents) and maximizes the mass spectrometric signal of the selected product ions. Design of experiments (DOE) and response surface methodology are applied throughout the procedure. The stepwise approach has the advantage of dealing with the different optimization criteria separately, i.e. first ensuring sufficient chromatographic separation, then maximizing the amount of precursor ion entering the mass spectrometer, and finally generating high amounts of selected product ions. The experiments are performed on a linear ion trap mass spectrometer. Retention mapping using the band-tracking model is applied during LC development, which facilitates the optimization of segmented gradients. A set of different siderophores, strong iron chelates, is used as the model substances.

  • 291. Moberg, My
    et al.
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Danielsson, Rolf
    Markides, Karin E
    Optimization strategy for liquid chromatography-electrospray ionization mass spectrometry methods2000In: Analyst, ISSN 0003-2654, Vol. 125, p. 1970-1976Article in journal (Refereed)
    Abstract [en]

    A strategy for the optimization of liquid chromatography (LC)–electrospray ionization mass spectrometry methods is proposed. The optimization aims at good chromatographic quality and a high signal-to-noise ratio for the analyte. The three-step strategy comprises screening experiments, LC studies and infusion experiments, using empirical modelling to evaluate the experimental data. The optimization route was examined for three different cases: (a) estriol in a mixture of estrogens, (b) ibuprofen and related metabolites in urine and (c) morphine in the presence of codeine

  • 292. Moberg, My
    et al.
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Markides, Karin
    Novel approach to the determination of structurally similar hydroxamate siderophores by column-switching capillary liquid chromatography coupled to mass spectrometry2003In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1020, no 1, p. 91-97Article in journal (Refereed)
    Abstract [en]

    In this study a new approach to determine three different siderophores (ferrichrome, ferrichrysin, ferricrocin) in natural soil solutions as well as in cultures of fungi is presented. The method includes enrichment of the analytes on a short pre-column, packed with C18 material, and subsequent highly selective separation of the analytes on a capillary porous graphitic carbon (PGC) column. In contrast to normal C18 packing materials, porous graphitic carbon offers chromatographic resolution between the three very similar analytes. The selectivity of the method is enhanced even further by the electrospray ionization (ESI) mass spectrometric detection. The combination of a short pre-column and a packed capillary separation column results in a method with high sensitivity. Reported detection limits, defined as the concentration giving the signal-to-noise ratio 3:1, is 27.7 pM for ferrichrome, 46.1 pM for ferricrocin and 37.4 pM for ferrichrysin.

  • 293. Moberg, My
    et al.
    Markides, Karin E
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Multi-parameter investigation of tandem mass spectrometry in a linear ion trap using response surface modelling2005In: Journal Of Mass Spectrometry, ISSN 1076-5174, Vol. 40, no 3, p. 317-324Article in journal (Refereed)
    Abstract [en]

    The feasibility of experimental design in combination with subsequent response surface modelling was illustrated for the prediction and interpretation of tandem mass spectrometric (MS/MS) fragmentation data using a linear quadrupole ion trap under various experimental conditions. The instrumental parameters included were (i) the pressure of the collision gas, (ii) the collision energy, (iii) the fill time of the linear ion trap and (iv) the scan rate. The spectral intensity and width of five fragment ions of the doubly charged neuro-active peptide bombesin were used for evaluation, and all experiments were performed so as to resemble the results obtained from a liquid chromatographic peak. The reported results show how fairly simple mathematical tools can be utilized successfully to describe fundamental mechanisms associated with multiple collisional activation and collision-induced dissociation processes without an extensively controlled experimental environment. Most beneficial, using the suggested approach, is the ability to study interaction (synergistic) effects between various parameters. As was realized from the results, many interaction effects are indeed significant. For example, the effect on the signal intensity of different collision gas pressure settings is strongly dependent on the settings of the other parameters. The described approach can easily be adopted for optimization purposes of any MS/MS experiment.

  • 294. Morozov, V. A.
    et al.
    Antzutkin, Oleg
    Koptyug, Andrey
    Institute of Chemical Kinetics and Combustion, Novosibirsk, USSR.
    Doktorov, A. B.
    Multiquantum resonances in low-field optically detected ESR of radical-ion pairs1991In: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 73, no 3, p. 517-540Article in journal (Refereed)
    Abstract [en]

    Multiquantum resonances in low-field optically-detected electron spin resonance (ESR) spectra of radiation-induced radical-ion pairs of aromatic acceptors in liquid and some polymeric solutions have been studied experimentally and theoretically. Corresponding resonances occur in spectra under the action of relatively intense radiofrequency (RF) pumping, when usual signals are inverse due to spin-locking effect. Special experiments have been carried out to prove that such resonances are not caused by the apparatus. The dependencies of resonance shifts and intensities on the radiofrequency field amplitude for various polarizations of the RF field have been studied. The case of pumping with two independent RF generators has also been analysed. A general theory for multiquarium optically detected ESR spectra of radicalion pairs in liquid solutions has been developed, with spin relaxation processes being neglected. The theory has been applied to calculating multiquantum resonance parameters in transverse RF fields (H1 ⊥ H0) of various polarizations. The mechanism of multiquantum resonance spin dynamics of radical pairs (RP) has been analysed in detail. The shapes of OD ESR spectra components have been studied for the Poisson distribution of RP lifetimes. The developed theory shows qualitative agreement with experimental results

  • 295.
    Mridha, Moniruzzaman
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. Uppsala University.
    Ma, Guangning
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Palo-Nieto, Carlos
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. Stockholm University.
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. Stockholm University.
    Development of an Amino Acid/Hydroxy Oxime Dual Catalyst System for Highly Stereoselective Direct Asymmetric Aldol Reactions in the Presence of Water2017In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, Vol. 49, no 2, p. 383-390, article id ss-2015-z0592-opArticle in journal (Refereed)
    Abstract [en]

    An eco-friendly dual catalyst system for stereoselective aldol reactions in the presence of water is described. It is based on the cooperative action of acyclic amino acids and H-bond donating hydroxy oxime catalysts. The synthetic utility of this dual catalyst system was further demonstrated by applying it as the key step in the expeditious and highly stereoselective total synthesis of D-lyxo-phytosphingosine (29% overall yield). Here the amino acid/hydroxy oxime system significantly accelerated the direct aldol reactions in the presence of water as compared to organic solvents. The stereo-and chemoselectivity were also significantly increased.

  • 296.
    Musa, Najihah
    et al.
    IFM Biology, Conservation Ecology Group, Linköping University, Linköping, Sweden .
    Andersson, Klas
    Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden .
    Burman, Joseph
    Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden .
    Andersson, Fredrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Jansson, Nicklas
    IFM Biology, Conservation Ecology Group, Linköping University, Linköping, Sweden .
    Paltto, Heidi
    IFM Biology, Conservation Ecology Group, Linköping University, Linköping, Sweden .
    Westerberg, Lars
    IFM Biology, Conservation Ecology Group, Linköping University, Linköping, Sweden .
    Winde, Inis
    Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden .
    Larsson, Mattias C.
    Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden .
    Bergman, Karl-Olof
    IFM Biology, Conservation Ecology Group, Linköping University, Linköping, Sweden .
    Milberg, Per
    IFM Biology, Conservation Ecology Group, Linköping University, Linköping, Sweden .
    Using Sex Pheromone and a Multi-Scale Approach to Predict the Distribution of a Rare Saproxylic Beetle2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 6, p. e66149-Article in journal (Refereed)
    Abstract [en]

    The European red click beetle, Elater ferrugineus L., is associated with wood mould in old hollow deciduous trees. As a result of severe habitat fragmentation caused by human disturbance, it is threatened throughout its distribution range. A new pheromone-based survey method, which is very efficient in detecting the species, was used in the present study to relate the occurrence of E. ferrugineus to the density of deciduous trees. The latter data were from a recently completed regional survey in SE Sweden recording >120,000 deciduous trees. The occurrence of E. ferrugineus increased with increasing amount of large hollow and large non-hollow trees in the surrounding landscape. Quercus robur (oak) was found to be the most important substrate for E. ferrugineus, whereas two groups of tree species (Carpinus betulus, Fagus sylvatica, Ulmus glabra, vs. Acer platanoides, Aesculus hippocastanum, Fraxinus excelsior, Tilia cordata) were less important but may be a complement to oak in sustaining populations of the beetle. The occurrence of E. ferrugineus was explained by the density of oaks at two different spatial scales, within the circle radii 327 m and 4658 m. In conclusion, priority should be given to oaks in conservation management of E. ferrugineus, and then to the deciduous trees in the genera listed above. Conservation planning at large spatial and temporal scales appears to be essential for long-term persistence of E. ferrugineus. We also show that occurrence models based on strategic sampling might result in pessimistic predictions. This study demonstrates how pheromone-based monitoring make insects excellent tools for sustained feedback to models for landscape conservation management.

  • 297.
    Månsson, P. E.
    et al.
    Swedish University of Agricultural Sciences, Alnarp.
    Schlyter, F.
    Swedish University of Agricultural Sciences, Alnarp.
    Eriksson, Carina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Sjödin, Kristina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Nonanoic acid, other alkanoic acids and related compounds as antifeedants in Hylobius abietis pine weevils2006In: Entomologia Experimentalis et Applicata, ISSN 0013-8703, E-ISSN 1570-7458, Vol. 121, no 3, p. 191-201Article in journal (Refereed)
    Abstract [en]

    A medium-length, straight-chain alkanoic acid, nonanoic acid, is known from laboratory microassays to be an antifeedant in adults of the large pine weevil, Hylobius abietis (L.) (Coleoptera: Curculionidae). Our hypothesis was that we could find new, less volatile alkanoic acids or related compounds suitable for field application and with improved long-term duration. Alkanoic acids of varying chain lengths (C6-C13) were tested for antifeedant activity in H. abietis adults. Microassay choice tests showed that straight-chain (C6-C11) alkanoic acids were active. However, high activities were restricted to the (C6-C10) acids, with the C9 (nonanoic acid) at 4 μmol cm-2 being the most active one. In a no-choice test on pine twigs, the antifeedant effect of C10 acid was lower than that of the C8 and C9 acids. In microassays, less volatile methyl-branched alkanoic acids exhibited lower antifeedant activities than did the corresponding straight-chain ones. However, the most active of the methyl-branched acids, 2-methyldecanoic acid, had an activity similar to that of nonanoic acid. Compounds related to nonanoic acid were either active (1-nonanol), weakly active (nonanoic anhydride), or inactive (nonanal, sodium nonanoate). The anhydride was highly active in the microassay, but less active on twigs. The antifeedant effects of the straight chain (C8-C10) alkanoic acids against pine weevil feeding were tested in the field. In contrast to the results from the twig tests, the less volatile C10 acid was more active in the field for the protection of transplants on fresh clear cuts over a 3-month period than both the C8 and C9 acids. Phytotoxic effects of the alkanoic acids were observed both in the field and in laboratory studies. If a protective layer of paraffin was applied to the stem prior to application of the alkanoic acids, these undesired side effects were reduced.

  • 298. Månsson, Per
    et al.
    Eriksson, Carina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Sjödin, Kristina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Antifeedants against Hylobius abietis pine weevils: An active compound in extract of bark of Tilia cordata linden2005In: Journal of Chemical Ecology, ISSN 0098-0331, Vol. 31, no 5, p. 989-1001Article in journal (Refereed)
    Abstract [en]

    Linden (Tilia cordata) bark contains antifeedants effective against the large pine weevil, Hylobius abietis. Soxhlet extraction of inner and outer bark resulted in an extract which showed antifeedant activity in a micro-feeding assay. The extract was fractionated by chromatography on silica gel using gradient elution with solvents of increasing polarity. The content of the fractions obtained was monitored by thin layer- and gas chromatography. Fractions of similar chemical composition were merged. Two of the 17 fractions showed antifeedant activity in the micro feeding assay. Nonanoic acid was identified in both of these fractions. Subsequent testing in the micro feeding assay showed that nonanoic acid possessed strong antifeedant activity against H. abietis adults.

  • 299.
    Nambu, Kei
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    van Hees, P. A. W.
    Essén, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Assessing centrifugation technique for obtaining soil solution with respect to leaching of low molecular mass organic acids from pine roots.2005In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 127, no 3-4, p. 263-269Article in journal (Refereed)
    Abstract [en]

    Centrifugation is a common technique to obtain soil solution. However, this method may disrupt living cells in the soil and release their contents into the soil solution. To examine this possibility, we compared leaching of low molecular mass organic acids (LMMOAs) and dissolved organic carbon (DOC) from the root of Scots pine (Pinus sylvestris) packed in quartz sand via extraction by centrifugation and milder procedures of water immersion and suction. Centrifugation enhanced leaching of shikimate appreciably; leaching of DOC, lactate, malate, and phosphate was also significantly enhanced. The concentration leached from the root was greater than 10 mu M for shikimate, and generally ranged between 0.5 and 5 mu M for the other acids. As for actual soil samples, this level of leaching could be appreciably large in upper mineral horizon(s) if the root density is as large as in our experiments and if the concentrations of LMMOAs in the soil matrix are relatively small.

  • 300.
    Nambu, Kei
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    van Hees, P A W
    Jones, D L
    Vinogradoff, S
    Lundström, Ulla S
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Composition of organic solutes and respiration in soils derived from alkaline and non-alkaline parent materials2008In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 144, no 3-4, p. 468-477Article in journal (Refereed)
    Abstract [en]

    Parent material greatly influences pedogenesis and soil nutrient availability and consequently we hypothesized that it would significantly affect the amount of organic solutes in soil, many of which have been implicated in rhizosphere processes linked to plant nutrient uptake. Consequently, we investigated the influence of two contrasting parent materials in which calcite was present or absent (alkaline and non-alkaline soils) on the concentrations of dissolved organic carbon (DOC), low-molecular weight organic acids (LMWOA) and glucose in soil solution. Both soils were under Norway spruce. The dynamics of LMWOAs in soil were also investigated using 14C-labelled citrate and oxalate. Some of the mineral horizons of the alkaline soils showed significantly higher concentrations of DOC, phenolics, and fumarate in soil solution and also a higher basal respiration. No major differences were seen in organic solute status in the organic horizons of the two soil types. LMWOAs were present at low concentrations in soil solution (< 1 to 25 µM). Their mineralization rate significantly decreased with soil depth, however, overall neither their concentration or half-life in soil was markedly affected by parent material. The alkaline soils had significantly higher CO2-to-soil organic C (SOC) ratios, and consequently SOC in the alkaline soils did not seem more chemically stable against mineralization. Considering possible DOC and CO2 efflux rates it was suggested that the equal or larger SOC stocks in alkaline mineral soils were most likely linked to a higher net primary productivity. In conclusion, our study found that parent material exerted only a small effect on the concentration and dynamics of organic solutes in soil solution. This suggests that in comparison to other factors (e.g. vegetation cover, climate etc) parent material may not be a major regulator of the organic solute pool in soil.

3456789 251 - 300 of 450
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf