miun.sePublications
Change search
Refine search result
1234567 51 - 100 of 439
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.
  • 51.
    Bydén Sjöbom, Malin
    et al.
    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 Natural Sciences.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Binary Phase Equilibria of Three alfa-Methylsubstituted Sodium Alkanoate Surfactant Systems.2003In: Journal of Colloid and Interface Science, ISSN 0021-9797, Vol. 257, no 2, p. 333-336Article in journal (Refereed)
    Abstract [en]

    In this work, we continue our study of methyl -substituted surfactants and present the aqueous binary phase diagrams of racemic sodium 2-methyloctanoate, -nonanoate, and -dodecanoate, respectively. All systems have very low Krafft temperatures within the solution phase, between 1 and 4 degreesC. The phase sequences of the two shorter surfactants are very similar to those of the unsubstituted sodium octanoate, although with somewhat different range of existence for the phases formed. The sodium 2-methyldodecanoate system is different from the unsubstituted sodium dodecanoate system, as the former seems to lack a hexagonal phase. The surfactant systems were delineated using H-2 NMR splittings and crossed polarizers, and combined with SAXS for determination of phase structure. 

  • 52.
    Bydén Sjöbom, Malin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Marques, Eduardo
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Khan, Ali
    Phase Equilibria of the Mixed Didodecyldimethylammonium Bromide-Taurodeoxycholate-Water System with a Large Solution Region.2005In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 269, no 1-3, p. 87-95Article in journal (Refereed)
    Abstract [en]

    The phase behavior over the entire concentration range for the system didodecyldimethylammonium bromide (DDAB)-sodium taurodeoxycholate (STDC)-water, at 25 degrees C, has been investigated, with emphasis on the DDAB-rich part. Polarizing microscopy, SAXS, H-2 NMR and H-1 self-diffusion NMR have been used in combination as probing techniques for phase behavior and microstructure. The system forms four major phases, all deriving from the respective binary surfactant systems. The two lamellar phases originating from the binary DDAB-water axis (D-I and D-II, at 3-30 and 83-91 wt.% DDAB, respectively) are only able to incorporate small amounts of STDC. The D-II phase solubilizes a comparatively higher amount of bile salt (up to ca. 6 wt.%), while the D, phase takes up less than 0.25 wt.%. From the STDC-water axis, a solution phase and a "hexagonal-like" liquid crystalline phase are derived, at 0-26 and 37-60 wt.% of STDC, respectively. Heterogeneous regions are also indicated on the basis of NMR and SAXS data. The most striking feature is the large extension of the isotropic solution phase, which originates from the water corner and curves toward the DDAB-rich side of the phase diagram. Even though at the upper limit of the solution phase the amount of water is reduced to 10 wt.%, the measured water and DDAB self-diffusion coefficients exclude the possibility of reverse-type structures.

  • 53. Byers, J
    et al.
    Högberg, Hans-Erik
    Unelius, C. R.
    Birgersson, G.
    Löfqvist, J.
    Structure-Activity Studies on Aggregation Pheromone Components of Pithyogenes chalcographus (Coleoptera: Scolytidae): All stereoisomers of Chalcogran and Methyl 2,4-Decadienoate1989In: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 15, no 2, p. 685-695Article in journal (Refereed)
  • 54.
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Chemometric tools for enhanced performance in liquid chromatography-mass spectrometry2001Doctoral thesis, monograph (Other scientific)
  • 55.
    Bylund, Dan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Bergens, Arne
    Jacobsson, S P.
    Optimisation of chromatographic separations by use of a chromatographic response function, empirical modelling and multivariate analysis1997In: Chromatographia, ISSN 0009-5893, Vol. 44, no 1/2, p. 74-80Article in journal (Refereed)
    Abstract [en]

    The chiral separation of the drug substance R,S-oxybutynin chloride on a reversed phase HPLC system has been optimised by use of empirical modelling and multivariate analysis. The separation was characterised by a new chromatographic response function developed to modulate both quality of separation and retention time. The study includes a comparison between three different multivariate techniques (multi-layer feed-forward neural networks, multiple linear regression and partial least squares regression) of their capabilities to model the new chromatographic response function and predict its value for new experiments. It was indicated that the most accurate models were achieved with neural networks, although partial least squares regression could also be used to solve the problem since it gives the major directions for the optimal settings of the variables.

  • 56.
    Bylund, Dan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Danielsson, Rolf
    Malmquist, Gunnar
    Markides, Karin A
    Chromatographic alignment by warping and dynamic programming as a pre-processing tool for PARAFAC modelling of liquid chromatography-mass spectrometry data2002In: Journal of Chromatography A, ISSN 0021-9673, Vol. 961, no 2, p. 237-244Article in journal (Refereed)
    Abstract [en]

    Solutes analysed with LC–MS are characterised by their retention times and mass spectra, and quantified by the intensities measured. This highly selective information can be extracted by multiway modelling. However, for full use and interpretability it is necessary that the assumptions made for the model are valid. For PARAFAC modelling, the assumption is a trilinear data structure. With LC–MS, several factors, e.g. non-linear detector response and ionisation suppression may introduce deviations from trilinearity. The single largest problem, however, is the retention time shifts not related to the true sample variations. In this paper, a time warping algorithm for alignment of LC–MS data in the chromatographic direction has been examined. Several refinements have been implemented and the features are demonstrated for both simulated and real data. With moderate time shifts present in the data, pre-processing with this algorithm yields approximately trilinear data for which reasonable models can be made.

  • 57.
    Bylund, Dan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Danielsson, Rolf
    Markides, Karin E
    Peak purity assessment in liquid chromatography-mass spectrometry2001In: Journal of Chromatography A,, ISSN 0021-9673, Vol. 915, no 1/2, p. 43-52Article in journal (Refereed)
    Abstract [en]

    Fixed-size moving window evolving factor analysis and base peak chromatograms have been used for peak purity detection in data generated with LC–MS. The two methods were evaluated with both real and simulated data and were found to be fast and complementary to each other. When a possibly impure peak is detected, it is suggested that further information can be obtained from local principal component analysis modelling and comparative mass chromatogram plots.

  • 58.
    Bylund, Dan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Henriksson, Anders E.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. Sundsvalls sjukhus.
    Proteomic approaches to identify circulating biomarkers in patients with abdominal aortic aneurysm2015In: American Journal of Cardiovascular Disease, ISSN 2160-200X, Vol. 5, no 3, p. 140-145Article, review/survey (Refereed)
    Abstract [en]

    Abdominal aortic aneurysm (AAA) is a common condition with high mortality when ruptured. Most clinicians agree that small AAAs are best managed by ultrasonographic surveillance. However, it has been stated in recent reviews that a serum/plasma biomarker that predicts AAA rupture risk would be a powerful tool in stratifying patients with small AAAs. Identification of such circulating biomarkers with traditional hypothesis driven studies has been unsuccessful. In this review we summarize six studies using different proteomic approaches to find new, potential plasma AAA biomarker candidates. In conclusion, by using proteomic approaches novel potential plasma biomarkers for AAA have been identified.

  • 59.
    Bylund, Dan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Norström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    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.
    Analysis of low molecular mass organic acids in natural waters by ion exclusion chromatography tandem mass spectrometry2007In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1176, no 1-2, p. 89-93Article in journal (Refereed)
    Abstract [en]

    A sensitive and selective method for the analysis of aliphatic low molecular mass organic acids (LMMOAs) in natural waters is presented. The method is based on separation with ion exclusion chromatography and detection with electrospray ionization tandem mass spectrometry (LC-MS/MS). The extra selectivity gained by applying MS/MS allows for a minimum of sample preparation and the use of a sub-optimal mobile phase regarding chromatographic resolution. Instead the mobile phase, comprising aqueous formic acid With methanol as organic modifier, was mainly optimized for maximum sensitivity and long term MS stability. Detection limits for malonic, fumaric, maleic, succinic, citraconic, glutaric, malic, alpha-ketoglutaric, tartaric, shikimic, trans-aconitic, cis-aconitic, isocitric and citric acid were in the range 1-50 nM, while the detection limits for pyruvic, oxalic and lactic acid were around 250 nM for an injection volume of 100 mu L. Due to their metal-chelating properties, these LMMOAs are all considered to affect the bioavailability of metals and to be involved in soil forming processes. It is thus of interest to be able to monitor their presence in natural waters, and the method developed within this work was successfully applied for the analysis of LMMOAs in soil solution and stream water samples.

  • 60.
    Bylund, Dan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Samskog, J
    Jacobsson, S.P.
    Markides, K.E.
    Classification of lactate dehydrogenase of different origin by liquid chromatography-mass spectrometry and multivariate analysis2003In: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 14, no 3, p. 236-240Article in journal (Refereed)
  • 61. Bäckström, P
    et al.
    Bergström, G
    Björkling, F
    Hui-Zhu, H
    Högberg, Hans-Erik
    Jacobsson, Ulla
    Guo-Qiang, L
    Löfqvist, J
    Norin, Torbjörn
    Wassgren, A.-B.
    Structures, Absolute Configurations and Syntheses of the Volatile Signals from three Sympatric Ant-Lion Species, Euroleon nostras Grocus bore and Myrmeleon formicarius (Neuroptera: Myrmeleontidae).1989In: Journal of Chemical Ecology, ISSN 0098-0331, Vol. 15, no 1, p. 61-80Article in journal (Refereed)
  • 62. Bäckström, Peter
    et al.
    Björkling, Fredrik
    Högberg, Hans-Erik
    Norin, Torbjörn
    New three-step synthesis of racemic and optically active ipsdienol from myrcene1983In: Acta Chemica Scandinavica Ser. B: Organic Chemistry and Biochemistry, ISSN 0302-4369, Vol. B37, no 1, p. 1-5Article in journal (Refereed)
  • 63. Bäckström, Petre
    et al.
    Björkling, Fredrik
    Högberg, Hans-Erik
    Norin, Torbjörn
    Cross-coupling of vinyl cuprates and allylic halides and synthesis of the Comstock Mealybug pheromone via photooxidation 2,6-dimethyl-2,5-heptadiene.1984In: Acta Chemica Scandinavica Ser. B - Organic chemistry and Biochemistry, ISSN 0302-4369, Vol. B38, no 9, p. 779-782Article in journal (Refereed)
  • 64.
    Bång, Joakim
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Purification, Stereoisomeric Analysis and Quantification of Biologically Active Compounds in Extracts from Pine Sawflies, African Butterflies and Orchid Bees2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Stereochemistry plays an important role in nature because biologically important molecules such as amino acids, nucleotides and sugars, only exist in enantiomerically pure forms. Semiochemicals carry messages, between the same species (pheromones) and between different species (allelochemicals). Both pheromones and allelochemicals can be used as environmentally friendly pest management. Many semiochemicals, i.e. behaviour modifying chemicals, consist of pure or well-defined mixtures of stereoisomers, where some of the other stereoisomers can be repellent. It is therefore important to be able to separate them to produce a synthetic pheromone in a mixture that is attractive.

    Pine sawflies are a family of insects that in some cases can be severe defoliators of conifer trees. Diprion pini, Diprion similis and Neodiprion sertifer are severe pests for these trees and have got the most attention in pine sawfly pheromone studies. The pheromone precursors are stored in the female body as long-chain secondary alcohols, which, when released, are esterified to acetates or propionates. The alcohols are chiral, and normally one of the stereoisomer is the main pheromone component, sometimes possible together with other stereoisomers as essential minor components.

    Bicyclus is a genus of African butterflies, and especially Bicyclus anynana has become a popular model for the study of life history evolution, morphology, mating choice and genetics. The wing pattern of Bicyclus differs depending on the season, with large eyespots during the rain-season and small or absent spots during the dry season.

     Euglossa is one of the genera among the orchid bees in the Neotropics that does not produce its own pheromone. Instead, the males collect fragrances from orchids and other sources and store them in a pocket in their hind legs. Both Bicyclus and Euglossa use semiochemicals similar to pine sawflies, and thus can be analysed by the same methods.

    Pheromones and other semiochemicals in insects are often present in low amounts in a complex matrix, and purification of the sample before chemical analysis is often required. A common method is gradient elution on a solid phase silica column. Separation of stereoisomers can be achieved either by using a column with a chiral stationary phase (CSP) or with pre-column derivatisation using a column with an achiral stationary phase (ASP) or a combination of both, with mass detection as the dominant detection method. The purpose of this work has been to improve the purification method, find suitable methods to separate the stereoisomers of secondary alcohols, and to apply this on extracts of insects.

    By selecting the right fractions to collect during gradient elution the purification method was optimised. To reduce plasticizer contamination from ordinary columns, solid phase columns of Teflon or glass were used. For pre-column derivatisation of different chiral alcohols various acid chlorides were tested. For the pine sawfly pheromone precursors enantiopure (2S)-2-acetoxypropionyl chloride was the best choice. To separate some of the stereoisomers achiral 2-naphthoyl chloride was used. For derivatisation of 6,10,14-trimethylpentadecan-2-ol (R)-trans-chrysanthemoyl chloride was the best choice. The derivatised alcohols were separated on different columns, both chiral and non-chiral. Varian FactorFour VF-23ms was chosen as a general-purpose column, the Agilent HP-88 column was the best column with an ASP of those tested, and the Chiraldex B-PA column (CSP) was the only one that could separate all eight stereoisomers of derivatised 3,7-dimethylundecan-2-ol, 3,7-dimethyldodecan-2-ol, and 3,7-dimethyltridecan-2-ol.

    To determine the stereoisomeric purity of standard solutions used in field experiments and extracts of different species of insects the optimised methods were applied. For extracts from B. anynana, Euglossa and Neodiprion lecontei this work describe the first determination of the stereochemistry of some of their semiochemicals.

    For the determination of the stereochemistry of chiral semiochemicals the methods for purification and separation presented herein have shown to be of great value. The results will hopefully contribute to a better understanding of the communication among insects, and ultimately to a more environmentally friendly pest control.

  • 65.
    Bång, Joakim
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Anderbrant, Olle
    Lund Univ, Dept Biol, Lund, Sweden.
    Stereoisomeric separation of derivatized 2-alkanols using gas chromatography – mass spectrometry: Sex pheromone precursors found in pine sawfly species2012In: Analytical Letters, ISSN 0003-2719, E-ISSN 1532-236X, Vol. 45, no 9, p. 1016-1027Article in journal (Refereed)
    Abstract [en]

    Stereoisomers of long-chain secondary alcohols are used as sex pheromone precursors among pine sawflies, which can be severe pest to conifers. To use the pheromone in environmentally friendly pest managements, methods are needed that can determine the exact stereochemistry of the precursor alcohols. Combinations of 11 acid chloride derivatives and 10 GC columns were evaluated for separation of the stereoisomers of 3,7-dimethylundecan-2-ol, 3,7-dimethyldodecan-2-ol, 3,7-dimethyltridecan-2-ol, 3,7-dimethyltetradecan-2-ol, and 3,7-dimethylpentadecan-2-ol. Derivatisation with (2S)-2-acetoxypropionyl chloride in combination with the Chiraldex B-PA column separated all eight stereoisomers of 3,7-dimethylundecan-2-ol, 3,7-dimethyldodecan-2-ol and 3,7-dimethyltridecan-2-ol. A combination of two different derivatisation methods was needed to separate all stereoisomers of the longer chained alcohols, 3,7-dimethyltetradecan-2-ol and 3,7-dimethylpentadecan-2-ol. An extract of the pine sawfly Neodiprion lecontei was also analysed, and the stereochemistry of the sex pheromone alcohol prcursor was determined to be (2S,3S,7S)-3,7-dimethylpentadecan-2-ol, at an amount of about 7 ng/female. This paper presents the first GC-MS-separation of all eight stereoisomers of 3,7-dimethylundecan-2-ol, 3,7-dimethyldodecan-2-ol and 3,7-dimethyltridecan-2-ol in a single analytical run, and also the first determination of the stereochemistry of the sex pheromone precursor of N. lecontei.

  • 66.
    Bång, Joakim
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sjödin, Kristina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Purification, Stereoisomeric Analysis and Quantification of Sex Pheromone Precursors in Female Whole Body Extracts from Pine Sawfly Species2011In: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 37, no 1, p. 125-133Article in journal (Refereed)
    Abstract [en]

    A GC-MS method to analyze the stereoisomeric composition of chiral secondary alcohols found in whole body extracts of pine sawfly females was developed. The tested alcohols were derivatized with optically pure (S)-2-acetoxypropionyl chloride prior to GC-MS analysis. Baseline separation was obtained for all sixteen stereoisomers of 3,7,9-trimethyltridecan-2-ol and for the four 3-methylpentadecan-2-ol stereoisomers. For 3,7-dimethyltridecan-2-ol, 3,7-dimethyltetradecan-2-ol and 3,7-dimethylpentadecan-2-ol baseline separation was obtained for 6 of the possible 8 stereoisomers. When a mixture of 16 stereoisomers of 3,7,11-trimethyltridecan-2-ol was tested, baseline separation of 7 peaks out of 16 possible was obtained. The investigated alcohols are pheromone precursors for some pine sawfly species that are severe defoliators of pine. Females from several Diprion, Neodiprion, Macrodiprion, Microdiprion, and Gilpinia species emit esters of such secondary alcohols as sex pheromones that attract males for mating. To quantify the small amounts of the precursor alcohol and its stereoisomeric composition found in whole body extracts from female pine sawflies, a purification method was optimized. An extract of 20 females of D. pini contained about 8 ng of (2 S,3 R,7 R)-3,7-dimethyltridecan-2-ol per female, and three extracts of 18, 20, and 90 females of N. sertifer contained between 5 and 13 ng of (2 S,3 S,7 S)-3,7-dimethylpentadecan-2-ol per female.

  • 67.
    Bökman, C.F.
    et al.
    Clinical Chemistry Laboratory, Falun Central Hospital, Falun.
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Markides, K.E.
    Department of Analytical Chemistry, Uppsala University, Uppsala.
    Sjöberg, P.J.R.
    Department of Analytical Chemistry, Uppsala University, Uppsala .
    Relating chromatographic retention and electrophoretic mobility to the ion distribution within electrosprayed droplets2006In: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 17, no 3, p. 318-324Article in journal (Refereed)
    Abstract [en]

    Ions that are observed in a mass spectrum obtained with electrospray mass spectrometry can be assumed to originate preferentially from ions that have a high distribution to the surface of the charged droplets. In this study, a relation between chromatographic retention and electrophoretic mobility to the ion distribution (derived from measured signal intensities in mass spectra and electrospray current) within electrosprayed droplets for a series of tetraalkylammonium ions, ranging from tetramethyl to tetrapentyl, is presented. Chromatographic retention in a reversed-phase system was taken as a measure of the analyte's surface activity, which was found to have a large influence on the ion distribution within electrosprayed droplets. In addition, different transport mechanisms such as electrophoretic migration and diffusion can influence the surface partitioning coefficient. The viscosity of the solvent system is affected by the methanol content and will influence both diffusion and ion mobility. However, as diffusion and ion mobility are proportional to each other, we have, in this study, chosen to focus on the ion mobility parameter. It was found that the influence of ion mobility relative to surface activity on the droplet surface partitioning of analyte ions decreases with increasing methanol content. This effect is most probably coupled to the decrease in droplet size caused by the decreased surface tension at increasing methanol content. The same observation was made upon increasing the ionic strength of the solvent system, which is also known to give rise to a decreased initial droplet size. The observed effect of ionic strength on the droplet surface partitioning of analyte ions could also be explained by the fact that at higher ionic strength, a larger number of ions are initially closer to the droplet surface and, thus, the contribution of ionic transport from the bulk liquid to the liquid/air surface interface (jet and droplet surface), attributable to migration or diffusion will decrease.

  • 68. Carlsson, Håkan
    et al.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Persson, Gerd
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Lindström, Birger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Competition Between Monovalent and Divalent Counterions in a Surfactant / Water System1996In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 180, no 2, p. 598-604Article in journal (Refereed)
    Abstract [en]

    Competition between mono- and divalent ions in the association of counterions to the headgroups of amphiphiles was studied in one surfactant system with organic counterions (piperidine+/piperazine2+octanesulfonate) and one with inorganic counterions (Na+/Ca2+octyl sulfate). By conductivity and13C NMR chemical shift measurements the critical micelle concentration (CMC) was found to decrease drastically when small amounts of divalent counterions were present in the system. Self-diffusion coefficients of surfactant ions and organic counterions were measured in the micellar phase by the Fourier transform pulsed-gradient spin-echo (FT-PGSE) NMR method. The degree of counterion binding in the micellar system with piperidine+/piperazine2+counterions was obtained from FT-PGSE NMR measurements. It was observed that the divalent counterions were more strongly bound than the monovalent counterions. The experimental results were compared with theoretical Poisson–Boltzmann calculations. The cell model was used to study the electrostatic effects. Good agreement between electrostatic theory and experiment was observed; however, an attractive force exists between the monovalent piperidine counterions and the micelle, probably because of hydrophobic interactions.

  • 69.
    Clancy, Gunilla
    et al.
    Chalmers University of Technology.
    Fröling, Morgan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Svanström, Magdalena
    Chalmers University of Technology.
    Changing from petroleum to wood-based materials: critical review of how product sustainability characteristics can be assessed and compared2013In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 39, p. 372-385Article, review/survey (Refereed)
    Abstract [en]

    This paper reports on a literature survey on available approaches for the assessment of product sustainability, with a specific focus on assessing the replacement of non-renewable petroleum-based materials with renewable wood-based materials in absorbent hygiene products. The results are contrasted to needs in a specific material development project. A diverse number of methods exist that can help in assessing different product sustainability characteristics for parts of or whole product lifecycles. None of the assessment methods found include guidelines for how to make a case-specific interpretation of sustainability and there is a general lack of assessment parameters that can describe considerations in the comparison between the use of wood or petroleum as main raw material. One reason for this is lack of knowledge and/or consensus on how to describe and assess impacts of land and water use, e.g. on ecosystem services, different types of resource depletion and social impacts.

  • 70.
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Combined heterogeneous metal/organic catalysts for eco-friendly synthesis2015In: Pure and Applied Chemistry, ISSN 0033-4545, E-ISSN 1365-3075, Vol. 87, no 9-10, p. 1011-1019Article in journal (Refereed)
    Abstract [en]

    The interplay and synergistic cooperation between homogeneous and heterogeneous catalyst systems is of utmost importance in nature. It is also applied in chemical synthesis. Here, it can allow for new reactivity, which is not possible by the employment of a single catalyst, and promote the catalysis of multiple transformations in a one-pot sequence. This could overall lead to novel reactions and the development of sustainable chemistry. In this context, a versatile and broad synergistic strategy for the selective synthesis of valuable molecules with variable complexity and under eco-friendly conditions is disclosed. It is based on integrated heterogeneous metal/organo multiple relay catalysis, which is performed in a single reaction vessel, and allows for the assembly of complex molecules (e.g., heterocycles and carbocycles) with up to three quaternary stereocenters in a highly enantioselective fashion from simple alcohols and air/O-2.

  • 71.
    Cordova, Armando
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Cihalova, Sylva
    Charles Univ Prague, Fac Sci, Dept Organ & Nucl Chem, Prague 12840, Czech Republic .
    Dziedzic, Pawel
    Univ Stockholm, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden.
    Vesely, Jan
    Charles Univ Prague, Fac Sci, Dept Organ & Nucl Chem, Prague 12840, Czech Republic .
    Asymmetric Aza-Morita-Baylis-Hillman-type reactions: The highly enantioselective reaction between unmodified α,β-unsaturated aldehydes and N-acyl imines by organo-co-catalysis2011In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, ISSN 1615-4150, Vol. 353, no 7, p. 1096-1108Article in journal (Refereed)
    Abstract [en]

    The highly enantioselective organo-co-catalytic aza-Morita-Baylis-Hillman (MBH)-type reaction between N-carbamate-protected imines and alpha,beta-unsaturated aldehydes has been developed. The organic co-catalytic system of proline and 1,4-diazabicyclo[2.2.2]octane (DABCO) enables the asymmetricsynthesis of the corresponding N-Boc- and N-Cbz-protected beta-amino-alpha-alkylidene-aldehydes in good to high yields and up to 99% ee. In the case of aza-MBH-type addition of enals to phenylprop-2-ene-1-imines, the co-catalytic reaction exhibits excellent 1,2-selectivity. The organo-co-catalytic aza-MBH-type reaction can also be performed by the direct highly enantioselective addition of alpha,beta-unsaturated aldehydes to bench-stable N-carbamate-protected alpha-amidosulfones to give the corresponding beta-amino-alpha-alkylidene-aldehydes with up to 99% ee. The organo-co-catalytic aza-MBH-type reaction is also an expeditious entry to nearly enantiomerically pure beta-amino-alpha-alkylidene-amino acids and beta-amino-alpha-alkylidene-lactams (99% ee). The mechanism and stereochemistry of the chiral amine and DABCO co-catalyzed aza-MBH-type reaction are also discussed.

  • 72.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Catalytic Asymmetric Conjugate Reactions2010Collection (editor) (Other academic)
    Abstract [en]

    Information from publisher:

    This unique and long-awaited handbook on this important topic in the hot field of stereoselective organic synthesis covers several types of nucleophiles. Top international authors deal with modern forms of achieving stereoselective conjugate additions based on the use of chiral ligands or asymmetric catalysis, such as P-N ligands, organocatalysis, domino reactions, Lewis acid and base catalysis. There is also a discussion of the employment of enantioselective conjugate addition transformations in total synthesis of important molecules. With its reliable and previously unpublished experimental procedures, this is a true source of high quality information.

  • 73.
    Córdova, Armando
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Breistein, Palle
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Deiana, Luca
    Zhao, Gui-Ling
    Dziedzic, Pawel
    Pirttilä, Kristian
    Lin, Shuangzheng
    TOC-Trends in Organic Chemistry: Selective Catalysis2010Conference paper (Other academic)
  • 74.
    Córdova, Armando
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    R., Rios
    Aziridine Formation: in C-N Bond Formation2012In: Comprehensive Chirality / [ed] Yamamoto, H.; Carreira, E. Eds, Oxford: Elsevier, 2012Chapter in book (Refereed)
  • 75.
    Dahlström, Christina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Sample Preparation Using Argon Ion Beam Milling2013In: Argon: Production, Characteristics and Applications / [ed] Bogos Nubar Sismanoglu, Homero Santiago Maciel, Marija Radmilovic-Radjenovic, Rodrigo Savio Pessoa (Physics Department, Lab of Optics and Spectroscopy, Lab of Plasmas and Processes and Lab of Mechanics, Heath and Waves, Technological Institute of Aeronaut, Hauppauge, NY: Nova Science Publishers, Inc., 2013, p. 223-240Chapter in book (Other academic)
    Abstract [en]

    Surface and cross section analysis can provide important information on material properties. It has, however, been difficult to characterise the internal structure at a micro scale using cross sections prepared with conventional methods, such as e.g. mechanical grinding and polishing, because these procedures can damage the surface and introduce artefacts. A few years ago, a new precision argon ion beam cross section polisher was shown to be a suitable sample preparation technique for microstructure characterisation. It produces high quality cross sections free from artefacts and distortions. This technique can be used for cross section preparation of a wide variety of materials including composites, metals, ceramics and polymers. Argon ion beam milling can also be used in combination with focused ion beam (FIB) as a final step to remove FIB-damaged layers before nano- and microstructure characterisation in high resolution transmission electron microscopy (HRTEM).

  • 76. Danielsson, Rolf
    et al.
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Markides, Karin E
    Matched filtering with background suppression for improved quality of base peak chromatograms and mass spectra in liquid chromatography-mass spectrometry2002In: Analytica Chimica Acta, ISSN 0003-2670, Vol. 454, no 2, p. 167-184Article in journal (Refereed)
    Abstract [en]

    A time domain filter that combines the properties of matched filtering and two-fold differentiation is presented. The filter coefficients are given by the second derivative of a Gaussian model peak, controlled by the setting of two parameters related to the chromatographic system. The fundamental characteristics of the filter were derived, and its applicability demonstrated for real liquid chromatography–mass spectrometry (LC–MS) data. The filter is primarily intended as a fast pre-processing step, for a mass chromatogram with 320 scans over 700 mass channels the computation time was 0.6 s on a standard PC. Base peak chromatograms with improved peak detection capability and mass spectra useful for compound identification were obtained with filtered data. The most significant effect of the described filter is background reduction due to the differentiation, which in combination with the matched filter can be performed with maintained or even improved signal-to-noise ratio.

  • 77. De la Rosa, M. P.
    et al.
    Holmström, Sara J. M.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Sposito, G
    Tebo, B. M.
    Bargar, J
    Systematic study of the effect of pH on the structure and reactivity of Mn oxide produced by Bacillus sp., strain SG-1: Gordon Research Conferences - Environmental Bioinorganic Chemistry 2006. Proctor Academy , Andover, NH, USA, 18-23 June, 2006 ; Poster2006Conference paper (Refereed)
  • 78.
    Deiana, L.
    et al.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden .
    Ghisu, L.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden .
    Córdova, O.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden .
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Zhang, Renyun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden .
    Efficient and highly enantioselective aerobic oxidation-michael- carbocyclization cascade transformations by integrated Pd(0)-CPG nanoparticle/chiral amine relay catalysis2014In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, Vol. 46, no 10, p. 1303-1310Article in journal (Refereed)
    Abstract [en]

    A series of highly diastereo- and enantioselective aerobic oxidation-Michael-carbocyclization cascade transformations by integrated heterogeneous Pd(0)-CPG nanoparticle/chiral amine relay catalysis are disclosed. The heterogeneous Pd(0)-CPG nanoparticle catalysts were efficient for both the sequential aerobic oxidation and dynamic kinetic asymmetric Michael- carbocyclization transformations, resulting in 1) oxidation of a variety of allylic alcohols to enals and 2) formation of cyclopentenes containing an all-carbon quaternary stereocenter in good to high yields with up to 20:1 dr and 99.5:0.5 er. © Georg Thieme Verlag Stuttgart.New York.

  • 79. Deiana, L
    et al.
    Zhao, G-L
    Lin, S
    Dziedzic, P
    Zhang, Q
    Leijonmarck, H
    Còrdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Organocatalytic enantioselective aziridination of α-substituted α,β-unsaturated aldehydes: Asymmetric synthesis of terminal aziridines2010In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 352, no 18, p. 3201-3207Article in journal (Refereed)
    Abstract [en]

    The first example of a highly enantioselective organocatalytic aziridination of α-substituted α,β-unsaturated aldehydes is presented. The reaction is catalyzed by simple chiral amines and gives access to highly functional terminal azirdines containing an α-tertiary amine stereocenter in high yields and enantiomeric ratios (95.5:4.5-98:2)

  • 80.
    Deiana, Luca
    et al.
    Univ Stockholm, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Palo-Nieto, Carlos
    Univ Stockholm, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Verho, Oscar
    Univ Stockholm, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Johnston, Eric V
    Univ Stockholm, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Highly Enantioselective Cascade Transformations by Merging Heterogeneous Transition Metal Catalysis with Asymmetric Aminocatalysis2012In: Scientific reports, ISSN 2045-2322, Vol. 2, p. Art. no. 851-Article in journal (Refereed)
    Abstract [en]

    The concept of combining heterogeneous transition metal and amine catalysis for enantioselective cascade reactions has not yet been realized. This is of great advantage since it would allow for the recycling of expensive and non-environmentally friendly transition metals. We disclose that the use of a heterogeneous Pd-catalyst in combination with a simple chiral amine co-catalyst allows for highly enantioselective cascadetransformations. The preparative power of this process has been demonstrated in the context of asymmetric cascade Michael/carbocyclizationtransformations that delivers cyclopentenes bearing an all carbon quaternary stereocenters in high yields with up to 30:1 dr and 99% ee. Moreover, a variety of highly enantioselective cascade hetero-Michael/ carbocyclizations were developed for the one-pot synthesis of valuable dihydrofurans and pyrrolidines (up to 98% ee) by using bench-stable heterogeneous Pd and chiral amines as co-catalysts. © 2012 Macmillan Publishers Limited. All rights reserved.

  • 81.
    Deiana, Luca
    et al.
    Stockholm Univ, S-10691 Stockholm, Sweden.
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. Stockholm Univ, S-10691 Stockholm, Sweden.
    Nieto, Carlos Palo
    Stockholm Univ, S-10691 Stockholm, Sweden.
    Jiang, Yan
    Stockholm Univ, S-10691 Stockholm, Sweden.
    Johnston, Eric
    Stockholm Univ, S-10691 Stockholm, Sweden.
    Verho, Oscar
    Stockholm Univ, S-10691 Stockholm, Sweden.
    Combined multistep heterogeneous transition metal catalysis and aminocatalysis for asymmetric cascade reactions2013In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245, p. Meeting abstract 147-ORGN-Article in journal (Other academic)
  • 82.
    Deiana, Luca
    et al.
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Dziedzic, Pawel
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Zhao, Gui-Ling
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Vesely, Jan
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Ibrahem, Ismail
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Rios, Ramon
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Sun, Junliang
    Stockholm Univ, Arrhenius Lab, Dept Struct Chem, S-10691 Stockholm, Sweden.
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics. Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden.
    Catalytic Asymmetric Aziridination of alpha,beta-Unsaturated Aldehydes2011In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, no 28, p. 7904-7917Article in journal (Refereed)
    Abstract [en]

    The development, scope, and application of the highly enantioselective organocatalytic aziridination of α,β-unsaturated aldehydes is presented. The aminocatalytic azirdination of α,β-unsaturated aldehydes enables the asymmetric formation of β-formyl aziridines with up to >19:1 d.r. and 99 % ee. The aminocatalytic aziridination of α-monosubstituted enals gives access to terminal α-substituted-α-formyl aziridines in high yields and up to 99 % ee. In the case of the organocatalytic aziridination of disubstituted α,β-unsaturated aldehydes, the transformations were highly diastereo- and enantioselective and give nearly enantiomerically pure β-formyl-functionalized aziridine products (99 % ee). A highly enantioselective one-pot cascade sequence based on the combination of asymmetric amine and N-heterocyclic carbene catalysis (AHCC) is also disclosed. This one-pot three-component co-catalytic transformation between α,β-unsaturated aldehydes, hydroxylamine derivatives, and alcohols gives the corresponding N-tert-butoxycarbonyl and N-carbobenzyloxy-protected β-amino acid esters with ee values ranging from 92-99 %. The mechanisms and stereochemistry of all these catalytic transformations are also discussed.

  • 83.
    Deiana, Luca
    et al.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden.
    Ghisu, Lorenza
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden.
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Verho, Oscar
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden.
    Johnston, Eric V.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden.
    Hedin, Niklas
    Berzelii Center EXSELENT, Stockholm University, SE-106 91 Stockholm, Sweden.
    Bacsik, Zoltan
    Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-106 91, Sweden .
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden .
    Enantioselective Heterogeneous Synergistic Catalysis for Asymmetric Cascade Transformations2014In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 356, no 11-12, p. 2485-2492Article in journal (Refereed)
    Abstract [en]

    A modular design for a novel heterogeneous synergistic catalytic system, which simultaneously activates the electrophile and nucleophile by the combined activation modes of a separate metal and non-metal catalyst, for asymmetric cascade transformations on a solid surface is disclosed. This modular catalysis strategy generates carbocycles (up to 97.5: 2.5 er) as well as spirocyclic oxindoles (97.5: 2.5 to > 99: 0.5 er), containing all-carbon quaternary centers, in a highly enantioselective fashion via a one-pot dynamic relay process.

  • 84.
    Deiana, Luca
    et al.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm, Sweden.
    Jiang, Yan
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm, Sweden.
    Palo-Nieto, Carlos
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm, Sweden.
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Incerti-Pradillos, Celia A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Verho, Oscar
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm, Sweden.
    Tai, Cheuk-Wai
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm, Sweden .
    Johnston, Eric V.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm, Sweden.
    Cordova, Armando
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm, Sweden.
    Combined Heterogeneous Metal/Chiral Amine: Multiple Relay Catalysis for Versatile Eco-Friendly Synthesis2014In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 53, no 13, p. 3447-3451Article in journal (Refereed)
    Abstract [en]

    Herein is described a versatile and broad synergistic strategy for expansion of chemical space and the synthesis of valuable molecules (e.g. carbocycles and heterocycles), with up to three quaternary stereocenters, in a highly enantioselective fashion from simple alcohols (31examples, 95:5 to >99.5:0.5 e.r.) using integrated heterogeneous metal/chiral amine multiple relay catalysis and air/O-2 as the terminal oxidant. A novel highly 1,4-selective heterogeneous metal/amine co-catalyzed hydrogenation of enals was also added to the relay catalysis sequences.

  • 85. Deiana, Luca
    et al.
    Zhao, Gui-Ling
    Dziedzic, Pawel
    Rios, Ramon
    Vesely, Jan
    Ekström, Jesper
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    One-pot highly enantioselective catalytic Mannich-type reactions between aldehydes and stable a-amido sulfones: Asymmetric synthesis of b-amino aldehydes and b-amino acids2010In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 51, no 2, p. 234-237Article in journal (Refereed)
    Abstract [en]

    A highly enantioselective catalytic route to carbamate- and benzoate-protected β-amino aldehydes and β-amino acids is presented. The amino acid-catalyzed one-pot asymmetric reaction between unmodified aldehydes and α-amido sulfones gives the corresponding β-amino compounds with up to 95:5 dr and 97–>99% ee.

  • 86.
    Dijkstra, F. A.
    et al.
    Laboratory of Soil Science and Geology, PO Box 37, 6700 AA Wageningen, PAYS-BAS.
    Geibe, Christine
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    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.
    van Breemen, N.
    Laboratory of Soil Science and Geology, PO Box 37, 6700 AA Wageningen, PAYS-BAS.
    The effect of organic acids on base cation leaching from forest floor under six north American tree species2001In: European Journal of Soil Science, ISSN 1351-0754, E-ISSN 1365-2389, Vol. 52, no 2, p. 205-214Article in journal (Refereed)
    Abstract [en]

    Organic acidity and its degree of neutralization in the forest floor can have large consequences for base cation leaching under different tree species. We investigated the effect of organic acids on base cation leaching from the forest floor under six common North American tree species. Forest floor samples were analysed for exchangeable cations and forest floor solutions for cations, anions, simple organic acids and acidic properties. Citric and lactic acid were the most common of the acids under all species. Malonic acid was found mainly under Tsuga canadensis (hemlock) and Fagus grandifolia (beech). The organic acids were positively correlated with dissolved organic carbon and contributed significantly to the organic acidity of the solution (up to 26%). Forest floor solutions under Tsuga canadensis contained the most dissolved C and the most weak acidity among the six tree species. Under Tsuga canadensis we also found significant amounts of strong acidity caused by deposition of sulphuric acid from the atmosphere and by strong organic acids. Base cation exchange was the most important mechanism by which acidity was neutralized. Organic acids in solution from Tsuga canadensis, Fagus grandifolia, Acer rubrum (red maple) and Quercus rubra (red oak) were hardly neutralized while much more organic acidity was neutralized for Acer saccharum (sugar maple) and Fraxinus americana (white ash). We conclude that quantity, nature and degree of neutralization of organic acids differ among the different tree species. While the potential for base cation leaching with organic acids from the forest floor is greatest under Tsuga canadensis, actual leaching with organic anions is greatest under Acer saccharum and Fraxinus americana under which the forest floor contains more exchangeable cations than does the strongly acidified forest floor under Tsuga canadensis.

  • 87.
    Duan, Ran
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    On Shaping Mechanical Properties of Lignocellulosic Materials by Benign Chemical Processing2016Licentiate thesis, comprehensive summary (Other academic)
  • 88. Duckworth, O W
    et al.
    Holmström, Sara J M
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Peña, J
    Sposito, G
    Biogeochemistry of iron oxidation in a circumneutral freshwater habitat2009In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 260, no 3-4, p. 149-158Article in journal (Refereed)
    Abstract [en]

    Iron(II) oxidation in natural waters at circumneutral pH, often regarded as an abiotic process, is frequently biologically mediated at iron-rich redox gradients. West Berry Creek, a small circumneutral tributary that flows through a mixed coniferous forest in Big Basin State Park, California, contains localized iron (hydr)oxide precipitates at points along its course where anoxic groundwater meets oxygenated creek water. These mixing zones establish redox gradients that may be exploited by microbes forming microbial mats that are intimately associated with iron (hydr)oxide precipitates. Water sampling revealed strong correlations between the concentrations of aqueous inorganic species, suggesting a rock-weathering source for most of these solutes. Liquid chromatography-electrospray ionization-mass spectrometry techniques detected significant concentrations of organic exudates, including low molecular mass organic acids and siderophores, indicating that active biogeochemical cycling of iron is occurring in the creek. X-ray diffraction and elemental analysis showed the precipitates to be amorphous, or possibly poorly crystalline, iron-rich minerals. Clone libraries developed from 16S rDNA sequences extracted from microbial mat communities associated with the precipitates revealed the presence of microorganisms related to the neutrophilic iron oxidizing bacteria Gallionella and Sideroxydans. Sequences from these libraries also indicated the presence of significant populations of organisms related to bacteria in the genera Aquaspirillum, Pseudomonas, Sphingomonas, and Nitrospira. These geosymbiotic systems appear to be significant not only for the biogeochemical cycling of iron in the creek, but also for the cycling of organic species, inorganic nutrients, and trace metals.

  • 89.
    Edlund, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Berglund, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Jensen, 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.
    Resolution of 2-Methylalkanoic Acids: Enantioselective Esterification with Long Chain Alcohols Catalysed by Candida rugosa Lipase1996In: Acta Chemica Scandinavica, ISSN 0904-213X, Vol. 50, no 8, p. 666-671Article in journal (Refereed)
  • 90.
    Edlund, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Different Types of Aggregation and Aggregate Structures in Aqueous Kraft Lignin Solutions. 2002In: Proceedings. 7th EWLP, 2002, p. 297-300Conference paper (Other scientific)
  • 91.
    Edlund, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Ion Specific Differences in Salt Induced Precipitation of Kraft Lignin2002In: Proceedings 7th EWLP, Turku, Finland, Aug 26–29, 2002, 2002, p. 75-78Conference paper (Refereed)
  • 92.
    Eivazihollagh, Alireza
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Bäckström, Joakim
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Norgren, Magnus
    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.
    Electrochemical recovery of copper complexed by DTPA and C12-DTPA from aqueous solution using a membrane cell2018In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 93, no 5, p. 1421-1431Article in journal (Refereed)
    Abstract [en]

    BACKGROUND

    The electrochemical recovery of copper from DTPA and C12-DTPA (a surface-active derivative of DTPA) complex solutions was investigated in a membrane flow cell. Electrolysis time, solution flow rate, applied current density, and solution pH were evaluated.

    RESULTS

    The chelating surfactant C12-DTPA can promote the kinetics of copper electrodeposition more than DTPA depending on the experimental conditions. At a current density of 30 A m–2, a solution flow rate of 0.6 L min–1, and pH 10 after 180 min treatment, the copper recovery and current efficiency were 50% and 43.3%, respectively, in the Cu(II)-DTPA system and about 65% and 53.6%, respectively, in the Cu(II)-C12-DTPA system. The differences in the amount of recovery could be explained in terms of differences in the diffusion of copper complexes with DTPA and C12-DTPA to the cathode, as well as their solution behavior and pH-dependent conditional stability constants (log10 K’CuDTPA3-).

    CONCLUSION

    Electrochemical methods could be effectively combined with foam flotation for the chelating surfactant C12-DTPA, to recover copper and C12-DTPA. This makes the overall treatment more sustainable, and can be helpful in complying with the increasingly stringent environmental regulations

  • 93.
    Eivazihollagh, Alireza
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Bäckström, Joakim
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Norgren, Magnus
    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.
    Influences of the operational variables on electrochemical treatment of chelated Cu(II) in alkaline solutions using a membrane cell2017In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 92, no 6, p. 1436-1445Article in journal (Refereed)
    Abstract [en]

    BACKGROUND

    The electrochemical recovery of copper and chelating agent from their complex solution using a membrane flow cell was investigated. The parameters electrolysis time, solution pH, current density, and temperature were investigated.

    RESULTS

    Electrochemical investigation indicated that chelating ligands can be recovered by the electrodeposition of copper ions on the cathode. For copper and EDTA recovery, the results indicated that recovery efficiency was affected by time, current density, and temperature. The recovery process was not influenced by pH in the range studied (pH 8–12), which can be explained by the low variation in the conditional stability constant, i.e. Δlog10 K' ≤ 0.7, over the pH range. However, when NTA, EDTA, and DTPA were compared, the results indicated that the recovery efficiency decreased as the conditional stability constant of the chelating agent–Cu(II) complex increased. The maximum current efficiency of copper and EDTA recovery after 5 h of treatment was approximately 85%, whereas the recovery was 80% of the initial concentration (0.05 mol L−1) at a current density of 1 A dm−2, temperature of 333 K, and pH of 10.

    CONCLUSION

    Relatively high recovery efficiency makes the process fairly sustainable and hinders the discharge of copper ions and chelating ligands as pollutants into the environment. 

  • 94. Ellis, Gemma L
    et al.
    Amewu, Richard
    Sabbani, Sunil
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Stocks, Paul A
    Shone, Alison
    Stanford, Deborah
    Gibbons, Peter
    Davies, Jill
    Vivas, Livia
    Charnaud, Sarah
    Bongard, Emily
    Hall, Charlotte
    Rimmer, Karen
    Lozanom, Sonia
    Jesús, Maria
    Two-Step synthesis of Achiral Dispiro-1,2,4,5-tetraoxanes with outstanding antimalarial activity, low toxicity, and high-stability profiles2008In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 51, no 7, p. 2170-2177Article in journal (Refereed)
    Abstract [en]

    A rapid, two step synthesis of a range of dispiro-1,2,4,5-tetraoxanes with potent antimalarial activity both in vitro and in vivo has been achieved. These 1,2,4,5-tetraoxanes have been proven to be superior to 1,2,4-trioxolanes in terms of stability and to be superior to trioxane analogues in terms of both stability and activity. Selected analogues have in vitro nanomolar antimalarial activity, good oral activity and are non-toxic in screens for both cytotoxicity and genotoxicity. The synthesis of a fluorescent NBD-tagged tetraoxane probe has allowed investigation into the mechanism of accumulation of these drugs using laser scanning confocal microscopy techniques.

  • 95. Eltz, Thomas
    et al.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Bång, Joakim
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Wallin, Erika A
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Andersson, Jimmy
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    (6R,10R)-6,10,14-Trimethylpentadecan-2-one, a Dominant and Behaviorally Active Component in Male Orchid Bee Fragrances2010In: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 36, no 12, p. 1322-1326Article in journal (Refereed)
    Abstract [en]

    6,10,14-Trimethylpentadecan-2-one (Hexahydrofarnesyl acetone; HHA) previously has been found to be a major component in tibial fragrances of male orchid bees, Euglossa spp. HHA is a chiral molecule with four possible stereoisomers, (6R,10R)-, (6R,10S)-, (6S,10R)-, and (6S,10S)-6,10,14-trimethylpentadecan-2-one. In the present study, we characterized HHA extracted from Euglossa as the pure enantiomer (6R,10R)-6,10,14-trimethylpentadecan-2-one. During bioassays in Mexico and Panama, the synthetic RR-isomer attracted males of six species of orchid bees, including three that were known to contain HHA in their tibial fragrances. Possible sources of HHA for wild bees are flowers of euglossophilous orchids and aroids. With a molecular weight of 268, HHA is the largest natural molecule known to attract male orchid bees in pure form. Its attractiveness to males suggests that low-volatility compounds have a function in male signals, e.g., serve as a "base note" in complex odor bouquets. © 2010 Springer Science+Business Media, LLC.

  • 96.
    Engqvist, Cecilia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Forsberg, Sven
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Andreasson, B
    Karlsson, O
    Lund University.
    Interactions between single latex particles and silica surfaces studied with AFM2007In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 302, no 1-3, p. 197-203Article in journal (Refereed)
    Abstract [en]

    The spreading of single styrene-acrylic latex particles on silicon oxide surfaces was studied using atomic force microscopy (AFM). Three latexes with different glass transition temperature (Tg) were used and the effects of temperature, time and preparation method were investigated. Particle sizes and shape were measured with AFM and the contact angles were calculated. The observed rate for the spreading of latex particles was low and it took several days before the particles reached steady state, even at temperatures well above their Tg. The experimental particle spreading results deviated with two orders of magnitude from predictions using the WLF equation for polymer diffusion. The deviation could be attributed to polymer-surface interactions that slowed down the particle spreading. The work of adhesion was calculated using two models. The results from using the regular Young-Dupré equation and a modified version of this equation that also included the mechanical properties (E-modulus and Poisson�s ratio) of the latexes, were compared. For soft latex particles the results from the two models agreed well and were of the order of 75 J/m2, but for glassy latexes the Young-Dupré equation underestimated the work of adhesion.

  • 97.
    Engström, Ann-Christine
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    UV-Vis spectrophotometry for analyzing the exfoliation of graphite in aqueous solutions2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Graphene has generated a great deal of interest all over the world in the last decade, mainly as a result of its unique properties such as high con-ductance and strength, which is of potential benefit for many electronic applications. One common strategy for producing increased quantities of few-layer graphene includes liquid-based methods, where graphite is peeled off or exfoliated. Ultraviolet-Visible (UV-Vis) spectrophotometry can be used for measuring the degree of exfoliation since the optical ab-sorbance at a given amount of graphite increases with the degree of exfo-liation. In this work, a UV-Vis method was tested where the exfoliated samples were stabilized with glycerol. This enabled measurements of both polydisperse samples directly after the exfoliation and also top-phase samples collected after gravitational sedimentation. Beer-Lam-bert’s law could be applied for quantifying the amount of exfoliated graphite in the samples. The samples were analyzed by focusing on the connection between absorbance, extinction and light scattering. It was found that the particle size and the contribution from light scattering de-creased at the presence of smaller particle sizes. It was also evident that the absorbance peak of graphite was shifted toward higher wavelengths as the exfoliation was progressed by repeated shearing. These are intri-guing results that warrant further studies as well as verification by alter-native spectroscopic analysis.In order to investigate the change in absorbance with different chemical and mechanical exfoliation conditions, studies were performed using a high-pressure capillary viscometer, ACAV A2. It was clear that an addi-tion of 2% polyacrylic acid (PAA) facilitated mixing and also increased the amount of dispersed graphite by more than six times. The mechanical treatment showed that both high-pressure shearing and sonication gave higher concentrations of nanographite compared to mechanical disper-sion by a rotary disperser. The overall conclusion of this study is that a combination of analysis is required for characterizing the particles. In or-der to quantify graphene, the analysis of chemical structure, inter-particle stability and flake cleanliness is very important.

  • 98.
    Eriksson, Carina
    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.
    Månsson, Per
    Schlyter, Fredrik
    Sjödin, Kristina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Strategier i sökandet efter gnaghämmare mot snytbaggen, Hylobius abietis: Föredrag, 19:e Organikerdagarna i Linköpng 20042004Conference paper (Other academic)
  • 99.
    Eriksson, Carina
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Månsson, P. E.
    Sjödin, Kristina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Schlyter, F
    Antifeedants and feeding stimulants in bark extracts of ten woody non-host species of the pine weevil, Hylobius abietis.2008In: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 34, no 10, p. 1290-1297Article in journal (Refereed)
  • 100.
    Eriksson, Carina
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Månsson, P
    Sjödin, Kristina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Searching for Pine Weevil Antifeedants: Finding an Active Compound in Bark from Linden, Tilia cordata: Joint meeting of International Society of Chemical Ecology and Phytochemical Society of North America, Ottawa, Canada 20042004Conference paper (Other academic)
1234567 51 - 100 of 439
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