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  • 251.
    Bourajoini, Hasna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rautio, Anne-Riikka
    Kordas, Krisztian
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Calcium manganese oxide catalysts for water oxidation: Unravelling the influence of various synthesis strategies2016Inngår i: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 79, s. 133-137Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract Three different mixed oxide catalysts primarily consisting of calcium and manganese oxides targeting artificial photosynthesis were synthesized and studied. According to the results, their catalytic activity for water oxidation was enhanced by the presence of mixed valence states of Mnn+ ions (3.0 ≤ n ≪ 4.0), while the specific surface area had negligible effect.

  • 252. Bouveresse, D. Jouan-Rimbaud
    et al.
    Pinto, Rui Climaco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Schmidtke, L. M.
    Locquet, N.
    Rutledge, D. N.
    Identification of significant factors by an extension of ANOVA-PCA based on multi-block analysis2011Inngår i: Chemometrics and Intelligent Laboratory Systems, ISSN 0169-7439, E-ISSN 1873-3239, Vol. 106, nr 2, s. 173-182Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 253.
    Bozaghian, Marjan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Characterization and synthesis of biodiesel from sludge available in the Umeå̊ region2014Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
  • 254.
    Bozaghian, Marjan
    et al.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology.
    Rebbling, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Larsson, Sylvia H.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology.
    Xiong, Shaojun
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Combustion characteristics of barley straw stored with CaCO3 using olivine and quartz as bed materials in fluidized bed combustion2017Konferansepaper (Fagfellevurdert)
  • 255.
    Branca, Carmen
    et al.
    Istituto di Ricerche sulla Combustione, C.N.R., P.le V. Tecchio, 80125 Napoli, Italy.
    Di Blasi, Colomba
    Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Università degli Studi di Napoli “Federico II”, P.le V. Tecchio, 80125 Napoli, Italy.
    Galgano, Antonio
    Istituto di Ricerche sulla Combustione, C.N.R., P.le V. Tecchio, 80125 Napoli, Italy.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Effects of the Torrefaction Conditions on the Fixed-Bed Pyrolysis of Norway Spruce2014Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, nr 9, s. 5882-5891Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fixed-bed pyrolysis of Norway spruce wood previously subjected to torrefaction at temperatures between 533 and 583 K and retention times between 8 and 25 min was studied. Although the thermal pretreatment always results in an increased production of char at the expense of volatile products, appropriate torrefaction conditions give rise to maximum percentages of anhydrosugars, guaiacols possessing a carbonyl group, and phenols in the liquid fraction. Other carbohydrates (e.g., acetic acid, formic acid, hydroxyacetaldehyde, hydroxypropanone, furfural, and furfuryl alcohol) and the large majority of guaiacols show continuously decreasing values. The percentages of carbon monoxide and carbon dioxide in the gas product remain approximately the same, but that of methane slightly increases. The pyrolysis temperatures of torrefied wood are lower than those of the raw material, mainly because of the partial or complete absence of the exothermic contribution associated with extractives and hemicellulose degradation.

  • 256. Brandt, Agnieszka
    et al.
    Gräsvik, John
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Hallett, Jason P
    Welton, Tom
    Deconstruction of lignocellulosic biomass with ionic liquids2013Inngår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 15, nr 3, s. 550-583Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    This paper reviews the application of ionic liquids to the deconstruction and fractionation of lignocellulosic biomass, in a process step that is commonly called pretreatment. It is divided into four parts: the first gives background information on lignocellulosic biomass and ionic liquids; the second focuses on the solubility of lignocellulosic biomass (and the individual biopolymers within it) in ionic liquids; the third emphasises the deconstruction effects brought about by the use of ionic liquids as a solvent; the fourth part deals with practical considerations regarding the design of ionic liquid based deconstruction processes.

  • 257. Bravo, Andrea G.
    et al.
    Bouchet, Sylvain
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Tolu, Julie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mateos-Rivera, Alejandro
    Bertilsson, Stefan
    Molecular composition of organic matter controls methylmercury formation in boreal lakes2017Inngår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, artikkel-id 14255Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A detailed understanding of the formation of the potent neurotoxic methylmercury is neededto explain the large observed variability in methylmercury levels in aquatic systems. While it is known that organic matter interacts strongly with mercury, the role of organic matter composition in the formation of methylmercury in aquatic systems remains poorly understood. Here we show that phytoplankton-derived organic compounds enhance mercurymethylation rates in boreal lake sediments through an overall increase of bacterial activity. Accordingly, in situ mercury methylation defines methylmercury levels in lake sediments strongly influenced by planktonic blooms. In contrast, sediments dominated by terrigenous organic matter inputs have far lower methylation rates but higher concentrations of methylmercury, suggesting that methylmercury was formed in the catchment and imported into lakes. Our findings demonstrate that the origin and molecular composition of organic matter are critical parameters to understand and predict methylmercury formation and accumulation in boreal lake sediments.

  • 258. Breitholtz, Magnus
    et al.
    Näslund, Maria
    Stråe, Daniel
    Borg, Hans
    Grabic, Roman
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Fick, Jerker
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    An evaluation of free water surface wetlands as tertiary sewage water treatment of micro-pollutants2012Inngår i: Ecotoxicology and Environmental Safety, ISSN 0147-6513, E-ISSN 1090-2414, Vol. 78, s. 63-71Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Increased attention is currently directed towards potential negative effects of pharmaceuticals and other micro-pollutants discharged into the aquatic environment via municipal sewage water. A number of additional treatment technologies, such as ozonation, have therefore been suggested as promising tools for improving the removal efficiency of pharmaceuticals in existing Sewage Treatment Plants (STPs). Constructed wetlands are also capable of removing a variety of micro-pollutants, including some pharmaceuticals, and could hence be a resource efficient complement to more advanced treatment technologies. The purpose of the present study was therefore to increase the knowledge base concerning the potential use of constructed wetlands as a treatment step to reduce emissions of organic micro-pollutants from municipal sewage effluents. Under cold winter conditions, incoming and outgoing waters from four Swedish free water surface wetlands, operated as final treatment steps of sewage effluent from municipal STPs, were sampled and analyzed for levels of a set of 92 pharmaceuticals and 22 inorganic components as well as assessed using subchronic ecotoxicity tests with a macro-alga and a crustacean.

    Sixty-five pharmaceuticals were detected in the range from 1ngL(-1) to 7.6μgL(-1) in incoming and outgoing waters from the four investigated wetlands. Although the sampling design used in the present study lacks the robustness of volume proportional to 24h composite samples, the average estimated removal rates ranged from 42% to 52%, which correlates to previous published values. The effects observed in the ecotoxicity tests with the macro-alga (EC(50)s in the range of 7.5-46%) and the crustacean (LOECs in the range of 11.25-90%) could not be assigned to either pharmaceutical residues or metals, but in general showed that these treatment facilities release water with a relatively low toxic potential, comparable to water that has been treated with advanced tertiary treatments.

    From the present study it can be concluded that constructed wetlands may provide a complementary sewage treatment option, especially where other treatment is lacking today. To fully remove micro-pollutants from sewage effluent, however, other more advanced treatment technologies are likely needed.

  • 259.
    Brodin, MArcus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Leach tests on MSWI bottomash from CHP Dåva to reduceCu, Pb and Zn2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 260.
    Broman, Karolina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    Kjemi i krise?2011Inngår i: Naturfag, ISSN 1504-4564, nr 1, s. 74-77Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 261.
    Broman, Karolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    Ekborg, Margareta
    School of Education, Malmö university.
    Johnels, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Chemistry in crisis?: Perspectives on teaching and learning chemistry in Swedish upper secondary schools2011Inngår i: NorDiNa: Nordic Studies in Science Education, ISSN 1504-4556, E-ISSN 1894-1257, Vol. 7, nr 1, s. 43-60Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Explanations for a decline in the number of students studying chemistry at advanced level all over the world have been sought for quite some time. Many students do not find chemistry relevant and meaningful and there have been difficulties in developing school chemistry courses that engage students sufficiently and tempt them to further studies in the field. In this study, Swedish upper secondary school students (Ns=372) and their teachers (Nt=18) answered a questionnaire on their experiences of the content and the working methods of their chemistry course. They were also given the opportunity to express ideas on how to make chemistry courses more interesting and meaningful. The results point out some subject areas as both easy and interesting, e.g. atomic structure; while other areas are hard to understand but still interesting, e.g. biochemistry. The students find chemistry lessons teacher-centred, something they appreciate. When teachers and students gave suggestions on how to improve the relevance of chemistry education at upper secondary level, more laboratory work and connections to everyday life were the most common proposals. But on the whole, these students seem quite satisfied with their chemistry courses.

  • 262.
    Broman, Karolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    Parchmann, Ilka
    IPN Leibniz Institute for Science and Mathematics Education, University of Kiel, Germany.
    Students' application of chemical concepts when solving chemistry problems in different contexts2014Inngår i: Chemistry Education Research and Practice, ISSN 1756-1108, E-ISSN 1756-1108, Vol. 15, nr 4, s. 516-529Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 263. Brommer, Sandra
    et al.
    Jantunen, Liisa M.
    Bidleman, Terry Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Harrad, Stuart
    Diamond, Miriam L.
    Determination of vapor pressures for organophosphate esters2014Inngår i: Journal of Chemical and Engineering Data, ISSN 0021-9568, E-ISSN 1520-5134, Vol. 59, nr 5, s. 1441-1447Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organophosphate compounds are ubiquitous in the environment and to better understand and predict their environmental transport and fate, well-defined physical-chemical properties are needed. The subcooled liquid-phase vapor pressures at 298.15 K (p298) were determined for 11 chlorinated and nonchlorinated phosphate flame retardants (PFRs) by the capillary gas chromatography retention time method (GC-RT). Values of log (p298/Pa) ranged from -5.22 to -1.32 and enthalpies of vaporization (δ l gH/kJ·mol-1) ranged from 82.0 to 109. Log (p298/Pa) by GC-RT showed good overall agreement with estimates using the Modified Grain Method (EpiSuite) and with the mean of experimental and in silico literature values, whereas values for the chlorinated PFRs appeared to be overestimated. SPARC modeling seriously underestimated p298, especially for the less volatile compounds. The Junge-Pankow adsorption model at 288.15 K predicted that most of the PFRs would be predominantly in the particulate phase in urban air and distributed between the particulate and gaseous phases in background air.

  • 264.
    Brostrom, Markus
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Nordin, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Pommer, Linda
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Branca, C.
    Di Blasi, C.
    Influence of torrefaction on the devolatilization and oxidation kinetics of wood2012Inngår i: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 96, s. 100-109Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Devolatilization and oxidation kinetics of torrefied wood have been studied by evaluating thermogravimetric curves measured in nitrogen and air at various heating rates. Samples consist of Norway spruce wood chips torrefied at several process temperatures and residence times. Data about untreated wood have also been obtained for comparison. Measured curves are well predicted by means of a five-reaction mechanism, consisting of three devolatilization reactions for the pseudo-components hemicellulose. cellulose and lignin and, in air, of two additional reactions for char devolatilization and combustion. The torrefaction pre-treatment only requires model modifications in the amounts of volatiles generated from the decomposition of pseudo-components, indicating that only their relative percentages and not their reactivities are modified. On the other hand, a slightly different thermal stability is found for the char generated from torrefied wood, which results in higher activation energy and lower reaction order for the oxidation step. Hence torrefaction conditions can affect the subsequent conversion characteristics of the char product. (C) 2012 Elsevier B.V. All rights reserved.

  • 265.
    Bruce, Stephen J
    et al.
    Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Jonsson, Pär
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Antti, Henrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Cloarec, Olivier
    Technologie Servier, 45000 Orleans, France.
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Marklund, Stefan L
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Klinisk kemi.
    Moritz, Thomas
    Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Evaluation of a protocol for metabolic profiling studies on human blood plasma by combined ultra-performance liquid chromatography/mass spectrometry: From extraction to data analysis2009Inngår i: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 372, nr 2, s. 237-249Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The investigation presented here describes a protocol designed to perform high-throughput metabolic profiling analysis on human blood plasma by ultra-performance liquid chromatography/mass spectrometry (UPLC/MS). To address whether a previous extraction protocol for gas chromatography (GC)/MS-based metabolic profiling of plasma could be used for UPLC/MS-based analysis, the original protocol was compared with similar methods for extraction of low-molecular-weight compounds from plasma via protein precipitation. Differences between extraction methods could be observed, but the previously published extraction method was considered the best. UPLC columns with three different stationary phases (C8, C18, and phenyl) were used in identical experimental runs consisting of a total of 60 injections of extracted male and female plasma samples. The C8 column was determined to be the best for metabolic profiling analysis on plasma. The acquired UPLC/MS data of extracted male and female plasma samples was subjected to principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS–DA). Furthermore, a strategy for compound identification was applied here, demonstrating the strength of high-mass-accuracy time-of-flight (TOF)/MS analysis in metabolic profiling.

  • 266.
    Buckland, Philip I.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet. Umeå universitet, Humanistiska fakulteten, Humlab.
    SEAD - The Strategic Environmental Archaeology Database Inter-linking Multiproxy Environmental Data with Archaeological Investigations and Ecology2013Inngår i: Archaeology in the Digital Era: Papers from the 40th Annual Conference of Computer Applications and Quantitative Methods in Archaeology (CAA), Southampton, 26-29 March 2012 / [ed] Graeme Earl, Tim Sly, Angeliki Chrysanthi, Patricia Murrieta-Flores, Constantinos Papadopoulos, Iza Romanowska & David Wheatley, Amsterdam University Press, 2013, Vol. 1, s. 320-331Konferansepaper (Fagfellevurdert)
    Abstract [en]

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

  • 267.
    Buckland, Philip I
    et al.
    Umeå universitet, Humanistiska fakulteten, Arkeologi och samiska studier.
    Johan, Olofsson
    Umeå universitet, Humanistiska fakulteten, Arkeologi och samiska studier.
    Engelmark, Roger
    Umeå universitet, Humanistiska fakulteten, Arkeologi och samiska studier.
    SEAD: Strategic Environmental Archaeology Database, planning report2006Rapport (Annet vitenskapelig)
    Abstract [en]

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

  • 268.
    Buevich, Alexei V
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lundberg, Susanne
    Sethson, Ingmar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Edlund, Ulf
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Backman, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    NMR studies of calcium-binding to mutant alpha-spectrin EF-hands2004Inngår i: CELLULAR & MOLECULAR BIOLOGY LETTERS, ISSN 1425-8153, Vol. 9, nr 1, s. 167-86Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 269. Bui, Hue T B
    et al.
    Vo, Duy D
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Chau, Yen N T
    Tu, Cuc T K
    Mai, Hieu V
    Truong, Kiet V
    Facile Synthesis of 4-Oxo-4H-quinolizine-2-carboxamide Derivatives2015Inngår i: Synthetic Communications, ISSN 0039-7911, E-ISSN 1532-2432, Vol. 45, nr 24, s. 2861-2868Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A facile synthetic method for the construction of 2-substituted-4-oxo-4H-quinolizine-based core structure has been successfully developed. The synthesis made use of a one-pot Stobbe condensation followed by cyclization starting from the commercially available 2-pyridinecarbaldehyde. The structure of the formed 4-oxo-4H-quinolizine-2-carboxylate was fully confirmed by mass spectra, H-1 NMR and C-13 NMR, correlation spectrography, heteronuclear multiple bond correlation, and heteronuclear single quantum coherence (HSQC) spectra. The ethyl carboxylate moiety was then further functionalized via direct aminolysis by a range of amines to afford the corresponding 4-oxo-4H-quinolizine-2-carboxamides 4a-i in moderate to good yields.

  • 270. Bui, Hue Thi Buu
    et al.
    Ha, Quy Thi Kim
    Oh, Won Keun
    Vo, Duy Duc
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Chau, Yen Nguyen Tram
    Tu, Cuc Thi Kim
    Pham, Em Canh
    Tran, Phuong Thao
    Tran, Loan Thi
    Mai, Hieu Van
    Microwave assisted synthesis and cytotoxic activity evaluations of new benzimidazole derivatives2016Inngår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 57, nr 8, s. 887-891Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Twelve new 2-quinolizinylbenzimidazole and 2-naphthalylbenzimidazole derivatives with various 5- and 6-positioned substituents (aza, H, CH3, Cl, NO2, NH2, OCH3), have been synthesized in moderate to excellent yields via the condensation of 4-oxo-4H-quinolizinecarbaldehyde or naphthalenecarbaldehyde with substituted o-phenylenediamines, o-nitroaniline, and 2,3-pyridinediamine using sodium metabisulfite or sodium hydrosulfite under microwave irradiation. The new benzimidazole derivatives were screened for their cytotoxic activity against the human breast cancer cell line (MCF-7). The results showed on one hand that 2-(substituted quinolizinyl)-1H-benzimidazoles (12bf) were less active (3–6 fold) than the positive control Tamoxifen (CC50 = 6.52 μM), and on the other hand, among the 2-(substituted naphthalyl)-1H-benzimidazoles series (13af), compounds 6,7,8-trimethoxy-3-(5-chloro-1H-benzo[d]imidazol-2-yl)naphthalen-1-ol (13c) (CC50 = 7.48 μM) and 6,7,8-trimethoxy-3-(5-methoxy-1H-benzo[d]imidazol-2-yl)naphthalen-1-ol (13f) (CC50 = 6.43 μM) were found to be as active as Tamoxifen.

  • 271.
    Bui, Nhat Thi Hong
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Polyhydroxyl and Polyphosphorylcholine functionalized Silica for Hydrophilic interaction liquid Chromatography- Synthesis, characterization and application2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis focuses on the development of new stationary phases for use in hydrophilic interaction liquid chromatography using TRIS-based and phosphorylcholine typed monomers and porous silica particles as starting substrates. In this thesis, several ways of polymerizing highly hydrophilic mono­mers onto pore surfaces of silica supports are described, based on several “grafting from” schemes. “Controlled/living” radical polymerizations including atom transfer radical polymerization (ATRP) and iniferter-mediated polymerization in conjunction with conventional free radical polymerization are demonstrated to be successful tools for grafting different hydrophilic monomers (polyhydroxyl and phosphorylcholine [meth]acrylamide/acrylates) onto the silica surfaces. Reaction solvents are proven to play an essential role to achieve efficient graft polymerization of activated silica surfaces with these amphiphilic vinylic monomers, which is difficult because of their restricted access to the activated surface in solvents that can be used because of solubility constraints.

    Two tentacle TRIS-based polymer grafted silica, namely TRIS-WAX – TRIS functionality bonded to silica via a C–N–C imine bond and TRIS-Amide – TRIS bonded to silica via an amide bond, prove to be useful as stationary phases for hydrophilic interaction chromatography (HILIC).The TRIS-WAX exhibits a mixed mode hydrophilic partitioning and weak anion exchange (HILIC/WAX) retention mechanism while retention by hydrophilic partitioning is the dominant mechanism on the neutral TRIS-Amide phase which lacks weak anion exchange (WAX) properties. Interestingly, both these phases have selectivities that are radically different from most commercial HILIC stationary phases.

    Finally, a method is demonstrated for synthesizing a stratified (graft-copolymerized) silica material based on N,N′-methylenebisacrylamide and 2-methacryloyloxyethyl phosphorylcholine (MPC) using a “controlled/living” photoiniferter-mediated polymerization from the N,N-diethyldithiocarbamate iniferter moiety immobilized silica surfaces. This polymerization method proves to be successful for graft-blockcopolymerization of different highly hydrophilic monomers onto the activated surfaces of porous silica. In this way, silica surfaces are grafted with a cross-linked amide-based hydrogel, on top of which a tentacle zwitterionic phosphorylcholine-typed layer is synthesized. The resulted material proves to be useful for HILIC separations and possesses different selectivity for the tested organic acids compared to that of commercial ZIC-cHILIC stationary phase.

  • 272.
    Bui, Nhat Thi Hong
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jiang, Wen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sparrman, Tobias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Irgum, Knut
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Synthesis of poly(N-[tris(hydroxymethyl)methyl]acrylamide) functionalized porous silica for application in hydrophilic interaction chromatography2012Inngår i: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 35, nr 23, s. 3257-3269Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Porous silica coated by a highly hydrophilic and nonionic tentacle-type polymeric layer was synthesized by free radical "grafting from" polymerization of N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]-2-propenamide (TRIS-acrylamide) in partly aqueous solutions. The radical initiator sites were incorporated on the silica surfaces via a two-step reaction comprising thionyl chloride activation and subsequent reaction with tert-butyl hydroperoxide. The surface-bound tert-butylperoxy groups were then used as thermally triggered initiators for graft polymerization of TRIS-acrylamide. The synthesized materials were characterized by diffusive reflectance Fourier transform infrared specotroscopy, X-ray photoelectron spectroscopy, and CHN elemental analysis. Photon correlation spectroscopy was used to determine changes in ζ-potentials resulting from grafting, (29) Si magic angle spinning nuclear magnetic resonance spectroscopy (MAS-NMR) spectroscopy was used to assess the ratio of silanol to siloxane groups in the substrate and the grafted material, and the changes in surface area and mesopore distribution were determined by nitrogen cryosorption. Chromatographic evaluation in hydrophilic interaction chromatography (HILIC) mode showed that the materials were suitable for use as stationary phases, featuring good separation efficiency, a comparatively high retention, and a selectivity that differed from most commercially available HILIC phases. A comparison of this neutral phase with a previously reported N-(2-hydroxypropyl)-linked TRIS-type hydrophilic tentacle phase with weak anion exchange functionality revealed substantial differences in retention patterns.

  • 273.
    Bui, Thai Q.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Khokarale, Santosh G.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shukla, Shashi Kant
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FI-20500 Åbo-Turku, Finland.
    Switchable Aqueous Pentaethylenehexamine System for CO2 Capture: an Alternative Technology with Industrial Potential2018Inngår i: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 6, nr 8, s. 10395-10407Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Herein we report the application of polyamine pentaethylenehexamine (PEHA, 3,6,9,12-tetraazatetradecane-1,14-diamine) in CO2 absorption with both neat PEHA and aqueous solutions thereof. The absorption of molecular CO2 in pure PEHA and in PEHA-water systems resulted in the formation of two chemical species, namely, PEHA carbamate and bicarbonate. It was observed that, upon formation of these species, both the CO2 absorption capacity and CO2 absorption rate were controlled by the amount of water in the system. During the CO2 absorption, the neat PEHA and 92 wt % PEHA were capable of forming carbamate species only while other aqueous analogues with higher dilution allowed for the formation of both carbamate and bicarbonate species upon exceeding 8 wt % water in the mixture. The CO2 uptake steadily increased with an increase in the water concentration in the solvent mixture and reached the maximum value of 0.25 g of CO2/(g of solvent) in the case of 56 wt % PEHA in water. However, in the case of more dilute systems (i.e., <56 wt % PEHA in water), the trend reversed and the CO2 loading decreased linearly to 0.05 g of CO2/(g of solvent) for 11 wt % PEHA in water. Meanwhile, it usually took shorter time to achieve the full CO2 absorption capacity (equilibrium) with increasing water content in all cases. The C-13 NMR analysis was used to quantify the relative amount of PEHA carbamate and bicarbonate, respectively, in reaction mixtures. The Kamle-Taft parameters (alpha, beta, and pi*) of aqueous solutions for different concentrations of PEHA were also studied taking advantage of various solvatochromic dyes and correlated with the CO2 absorption capacity. The thermally induced switchable nature of CO2-saturated neat and aqueous PEHA solutions for transformation of ionic PEHA carbamate and bicarbonate moieties to molecular PEHA is also represented. A comparison between aqueous PEHA and aqueous monoethanolamine (industrial solvent) for CO2 capture is reported. Hence, most importantly, a switchable PEHA system is demonstrated for reversible CO2 absorption processes.

  • 274.
    Bui Thi Hong, Nhat
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Verhage, Jeroen J
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Irgum, Knut
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Tris(hydroxymethyl)aminomethane-functionalized silica particles and their application for hydrophilic interaction chromatography2010Inngår i: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 33, nr 19, s. 2965-2976Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new method is presented for synthesizing a highly hydrophilic silica-based material for use in hydrophilic interaction chromatography. Porous silica particles used as a starting substrate were modified with 3-bromopropyl trichlorosilane and grafted with glycidyl methacrylate by controlled (“living”) atom transfer radical polymerization in order to introduce an oxirane-carrying reactive tentacle layer on the silica surface. The grafted material was thereafter subject to an oxirane ring opening reaction with tris(hydroxy-methyl)aminomethane in dimethylformamide to yield a polymer-bound equivalent of the well known and highly hydrophilic “TRIS” buffering substance. Chemical characterization was done by diffuse reflectance FT-IR, X-ray photoelectron spectroscopy, elemental analysis, and 1H NMR. Porosity and surface area examination was done with Brunauer–Emmett–Teller. Chromatographic application of the material was evaluated by separations of nucleic bases, small organic acids, and common nucleotides under mixed hydrophilic interaction chromatography and weak anion exchange conditions.

  • 275.
    Bui, Thinh Quang
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    ANALYSIS OFMERCURY THIOL COMPLEXESBY LC ICP-MS2019Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
  • 276.
    Bukhanko, Natalia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Leino, Anne-Riikka
    Microelectronics and Materials Physics Laboratories, University of Oulu, Finland.
    Kordas, Krisztian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Microelectronics and Materials Physics Laboratories, University of Oulu, Finland.
    Wärnå, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Continuous gas phase synthesis of 1-ethyl chloride from ethyl alcohol and hydrochloric acid over Al2O3-based catalysts: the ‘green’ route2013Inngår i: ACS Sustainable Chemistry & Engineering, Vol. 1, nr 8, s. 883-893Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The synthesis of 1-ethyl chloride in the gas-phase mixture of ethanol and hydrochloric acid over ZnCl2/Al2O3 catalysts was studied in a continuous reactor using both commercial and tailor-made supports. The catalytic materials were characterized by the means of structural (XPS, TEM, XRD, and BET) and catalytic activity (selectivity and conversion) measurements. The reaction parameters such as temperature, pressure, and feedstock flow rates were optimized for the conversion of ethanol to ethyl chloride. The new tailor-made highly porous Al2O3-based catalyst outperformed its commercial counterpart by exhibiting high conversion and selectivity (98%) at the temperature of 325 °C. Long-term stability tests (240 h) confirmed the excellent durability of the tailor-made alumina catalysts. The process demonstrated here poses an efficient and economic “green” large-scale on-site synthesis of this industrially important reactant in industry, where bioethanol is produced and 1-ethyl chloride is necessary, e.g., for ethylation of cellulose and synthetic polymer products. On-site in situ production of ethyl chloride avoids the problems associated with the transportation and storage of toxic and flammable 1-ethyl chloride.

  • 277.
    Bukhanko, Natalia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Forest Biomaterials Technology, Swedish University of Agricultural Science, Umeå, Sweden.
    Schwarz, Christopher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ngoc Pham, Tung
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Chemistry, The University of Danang - University of Science and Technology, Nguyen Luong Bang, Lien Chieu, Da Nang, Viet Nam.
    Siljebo, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wärnå, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rautio, Anne-Riikka
    Kordas, Krisztian
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Gas phase synthesis of isopropyl chloride from isopropanol and HCl over alumina and flexible 3-D carbon foam supported catalysts2017Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 542, nr 25, s. 212-225Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Isopropyl chloride synthesis from isopropanol and HCl in gas phase over ZnCl2 catalysts supported on Al2O3 as well as flexible carbon foam was studied in a continuous reactor. A series of catalytic materials were synthesised and characterised by BET, XPS, SEM, TEM, XRD and NH3-TPD methods. Catalytic activity tests (product selectivity and conversion of reactants) were performed for all materials and optimal reaction conditions (temperature and feedstock flow rates) were found. The results indicate that the highest yield of isopropyl chloride was obtained over 5 wt.% ZnCl2 on commercial Al2O3 (No. II) (95.3%). Determination of product mixture compositions and by-product identification were done using a GC-MS method. Carbon foam variant catalyst, 5 wt.% ZnCl2/C, was found to perform best out of the carbon-supported materials, achieving ∼75% yield of isopropyl chloride. The kinetic model describing the process in a continuous packed bed reactor was proposed and kinetic parameters were calculated. The activation energy for the formation of isopropyl chloride reaction directly from isopropanol and HCl was found to be ∼58 kJ/mol.

  • 278.
    Bukhanko, Natalia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wärnå, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FIN-20500, Turku/Åbo, Finland.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FIN-20500, Turku/Åbo, Finland.
    Kinetic modeling of gas phase synthesis of ethyl chloride from ethanol and HCl in fixed bed reactor2016Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 142, s. 310-317Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Kinetic modeling of gas-phase synthesis of ethyl chloride from ethanol and hydrochloric acid over high porous Al2O3 and 2 wt% ZnCl2/Al2O3 catalysts was studied in a continuous plug flow reactor in the temperature range of 200–325 °C. Two rival kinetic models were proposed that both describe the kinetics well. The kinetic parameters of the reaction were determined and activation energy values for ethyl chloride formation from ethyl alcohol and diethyl ether reactions were calculated.

  • 279. Butina, Karen
    et al.
    Loffler, Susanne
    Rhen, Mikael
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Richter-Dahlfors, Agneta
    Electrochemical sensing of bacteria via secreted redox active compounds using conducting polymers2019Inngår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 297, artikkel-id UNSP 126703Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bacterial infections and antibiotic resistance represent major global threats to public health. Current diagnostics use culture based assays that are reliable but slow, hence appealing for new rapid methods. Here we describe redox sensing as a novel concept for rapid, label-free detection of bacteria. We utilize a two-electrode poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) based sensor for detection of bacterially secreted redox-active compounds. Using purified redox-active compounds, we show the ability of the sensor to detect and quantify compounds in micromolar concentrations within minutes. When applied for detection and quantification of Salmonella, we show that secreted, low molecular weight redox compounds cause reduction of the PEDOT:PSS electrode. A potential role of redox sensing in infection diagnostics was demonstrated as uropathogenic strains of E. coli., Staphylococcus, Enterococcus, Pseudomonas, Proteus, and Klebsiella spp., major causes of complicated urinary tract infections, were successfully detected in complex media or processed urine. Since numerous bacterial species are capable of extracellular electron transfer, redox sensing may find use as a generic method for bacterial detection with applications in research laboatories, the clinic and industry alike.

  • 280.
    Bwanika, Harry Colyn
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Purification and crystallisation of streptococcal collagen binding proteins2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 281.
    Bylesjö, Max
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Latent variable based computational methods for applications in life sciences: Analysis and integration of omics data sets2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    With the increasing availability of high-throughput systems for parallel monitoring of multiple variables, e.g. levels of large numbers of transcripts in functional genomics experiments, massive amounts of data are being collected even from single experiments. Extracting useful information from such systems is a non-trivial task that requires powerful computational methods to identify common trends and to help detect the underlying biological patterns. This thesis deals with the general computational problems of classifying and integrating high-dimensional empirical data using a latent variable based modeling approach. The underlying principle of this approach is that a complex system can be characterized by a few independent components that characterize the systematic properties of the system. Such a strategy is well suited for handling noisy, multivariate data sets with strong multicollinearity structures, such as those typically encountered in many biological and chemical applications.

    The main foci of the studies this thesis is based upon are applications and extensions of the orthogonal projections to latent structures (OPLS) method in life science contexts. OPLS is a latent variable based regression method that separately describes systematic sources of variation that are related and unrelated to the modeling aim (for instance, classifying two different categories of samples). This separation of sources of variation can be used to pre-process data, but also has distinct advantages for model interpretation, as exemplified throughout the work. For classification cases, a probabilistic framework for OPLS has been developed that allows the incorporation of both variance and covariance into classification decisions. This can be seen as a unification of two historical classification paradigms based on either variance or covariance. In addition, a non-linear reformulation of the OPLS algorithm is outlined, which is useful for particularly complex regression or classification tasks.

    The general trend in functional genomics studies in the post-genomics era is to perform increasingly comprehensive characterizations of organisms in order to study the associations between their molecular and cellular components in greater detail. Frequently, abundances of all transcripts, proteins and metabolites are measured simultaneously in an organism at a current state or over time. In this work, a generalization of OPLS is described for the analysis of multiple data sets. It is shown that this method can be used to integrate data in functional genomics experiments by separating the systematic variation that is common to all data sets considered from sources of variation that are specific to each data set.

  • 282.
    Bylesjö, Max
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Cloarec, O.
    Rantalainen, M.
    Normalization and Closure2009Inngår i: Comprehensive Chemometrics: Chemical and Biochemical Data Analysis, VOLS 1-4 / [ed] Steven Brown, Romà Tauler, Beata Walczak, AMSTERDAM: Elsevier, 2009, s. A109-A127Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 283.
    Bylesjö, Max
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rantalainen, M.
    Model Based Preprocessing and Background Elimination: OSC, OPLS, and O2PLS2009Inngår i: Comprehensive Chemometrics: Chemical and Biochemical Data Analysis, VOLS 1-4 / [ed] Steven Brown, Romà Tauler, Beata Walczak, AMSTERDAM: Elsevier, 2009, s. A129-A138Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 284.
    Byström, Emil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Porous polymeric materials for chromatography: Synthesis, functionalization and characterization2009Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Background: Separation science is heavily reliant on materials to fulfill ever more complicated demands raised by other areas of science, notably the rapidly expanding molecular biosciences and environmental monitoring. The key to successful separations lies in a combination of physical properties and surface chemistry of stationary phases used in liquid chromatographic separation, and this thesis address both aspects of novel separation materials.

    Methods: The thesis accounts for several approaches taken during the course of my graduate studies, and the main approaches have been i) to test a wild-grown variety of published methods for surface treatment of fused silica capillaries, to ascertain firm attachment of polymeric monoliths to the wall of microcolumns prepared in silica conduits; ii) developing a novel porogen scheme for organic monoliths including polymeric porogens and macromonomers; iii) evaluating a mesoporous styrenic monolith for characterization of telomers intended for use in surface modification schemes and; iv) to critically assess the validity of a common shortcut used for estimating the porosity of monoliths prepared in microconduits; and finally v) employing plasma chemistry for activating and subsequently modifying the surface of rigid, monodisperse particles prepared from divinylbenzene.

    Results: The efforts accounted for above have resulted in i) better knowledge of the etching and functionalization parameters that determine attachment of organic monoliths prepared by radical polymerization to the surface of silica; ii) polar methacrylic monoliths with a designed macroporosity that approaches the desired "connected rod" macropore morphology; iii) estab¬lishing the usefulness of monoliths prepared via nitroxide mediated polymerization in gradient polymer elution chromatography; iv) proving that scanning electron microscopy images are of limited value for assessing the macroporous properties of organic monoliths, and that pore measurements on externally polymerized monolith cocktails do not represent the porous properties of the same cocktail polymerized in narrow confinements; and v) showing that plasma bromination can be used as an activation step for rigid divinylbenzene particles to act as grafting handles for epoxy-containing telomers, that can be attached in a sufficiently dense layer and converted into carboxylate cation exchange layer that allows protein separations in fully aqueous eluents.

  • 285. Byström, Emil
    et al.
    Nordborg, Anna
    Limé, Fredrik
    Dinh, Ngoc Phuoc
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Irgum, Knut
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Plasma brominated polymer particles as grafting substrate for thiol-terminated telomers2010Inngår i: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 33, nr 11, s. 1563-70Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A combined surface activation and "grafting to" strategy was developed to convert divinylbenzene particles into weak cation exchangers suitable for protein separation. The initial activation step was based on plasma modification with bromoform, which rendered the particles amenable to further reaction with nucleophiles by introducing Br to a surface content of 11.2 atom-%, as determined by X-ray photoelectron spectroscopy. Grafting of thiol-terminated glydicyl methacrylate telomers to freshly plasma activated surfaces was accomplished without the use of added initiator, and the grafting was verified both by reduction in bromine content and the appearance of sulfur-carbon linkages, showing that the surface grafts were covalently bonded. Following grafting the attached glydicyl methacrylate telomer tentacles were further modified by a two-step procedure involving hydrolysis to 2,3-hydroxypropyl groups and conversion of hydroxyl groups to carboxylate functionality by succinic anhydride. The final material was capable of baseline separating four model proteins in 3 min by gradient cation exchange chromatography in a fully aqueous eluent.

  • 286.
    Byström, Emil
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Viklund, Camilla
    Merck SeQuant AB, Umeå.
    Irgum, Knut
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Differences in porous characteristics of styrenic monoliths prepared by controlled thermal polymerization in molds of varying dimensions2010Inngår i: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 33, nr 2, s. 191-199Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nitroxide-mediated polymerization was used as a model system for preparing styrenic monolithic materials with significant mesopore contents in different mold formats, with the aim of assessing the validity of pore characterization of capillary monoliths by analysis of parallel bulk polymerized precursor solution. Capillary monoliths were prepared in 250 mm id fused silica tubes (quadruplicate samples, in total 17 m), and the batch polymerizations were carried out in parallel in 100 mL microvials and regular 2mL glass vials, both in quintuplicate. The monoliths recovered from the molds were characterized for their meso- and macroporous properties by nitrogen sorptiometry (three repeated runs on each sample), followed by a single analysis by mercury intrusion porosimetry. A total of 14 monolith samples were thus analyzed. A Grubbs’ test identified one regular vial sample as an outlier in the sorptiometric surface area measurements, and data from this sample were consequently excluded from the pore size calculations, which are based on the same nitrogen sorption data, and also from the mercury intrusion data set. The remaining data were subjected to single factor analyses of variance analyses to test if the porous properties of the capillary monoliths were different from those of the bulk monoliths prepared in parallel. Significant differences were found between all three formats both in their meso and macroporous properties. When the dimension was shrunk from conventional vial to capillary size, the specific surface area decreased from 52.274.7 to 34.671.7m2/g. This decrease in specific surface area was accompanied by a significant shift in median diameter of the through-pores, from 31073.9 to 544713 nm. None of these differences was obvious from the scanning electron micrographs that were acquired for each sample type. The common practice of determining the mesopore characteristics from analysis of samples prepared by parallel bulk polymerization and looking for changes in the macropore structure by visual assessment of SEMs are therefore both rather questionable, at least for monoliths of the kind used in this study.

  • 287.
    Bäfver, Linda
    et al.
    Pöyry SwedPower.
    Renström, Caroline
    Pöyry SwedPower.
    Fahlström, Johan
    Ragn-Sells.
    Enfält, Patrik
    EasyMining Sweden.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Holmén, Erik
    ENA Energi.
    Slambränsleblandningar: Förbränning och fosforutvinning2013Rapport (Annet vitenskapelig)
    Abstract [en]

    For sustainable phosphorus recycling, the phosphorus in sewage sludge needs to be recovered, as it is a major phosphorus-source. However, all sludge is not suitable for direct recycling on agricultural land, e.g. when the content of heavy metals is too high. To achieve an increased recycling of phosphorus from sewage sludge there is a need of research and development of alternative methods to return the phosphorus from sewage sludge to agricultural land.

    The aim of the project is to show that sewage sludge can be co-combusted with demolition wood in existing boilers, and that the ash can be processed for extraction of phosphorus, together with valuable by-products from the process. Further effects of the project will be the development of new knowledge about combustion with a high sludge to demolition wood ratio in a grate boiler (up to 45 % sludge with respect to wet mixture), which has not been studied in full-scale combustion earlier. The project's goal is to demonstrate mixing and combustion of fuel mixtures of sludge and demolition wood, and subsequent extraction of phosphorus from ash. The target groups for this work are energy companies, suppliers of grate boilers, municipalities, wastewater treatment plants and authorities.

    The project involves the mixing of sewage sludge and demolition wood, combustion-tests of the fuel mixtures and laboratory experiments on bottom ash and fly ash for phosphorus extraction using EasyMining Sweden's method for phosphorus extraction from ash. Extensive analyses have been carried out on fuel, bottom ash and fly ash, as well as thermodynamic equilibrium calculations on the formed compounds containing phosphorus.

    The experience of preparing sludge fuel mixtures shows that the mixtures should be prepared in the near future to when they are to be combusted, to avoid a composting process in the fuel. The project shows that it is possible to combust sludge fuel mixtures with an admixture of up to 45 % sludge relative wet fuel, in an existing grate boiler during one day. However, to combust sludge fuel mixtures over a longer period of time and at a higher load, modifications of the de-ashing system and the flue gas cleaning system are needed. The results indicate a reduced tendency of slagging on the fuel bed at the combustion of sludge mixtures. The analyses of the fly ash showed a trend towards less corrosive ash at combustion of sludge mixtures. The phosphorus content in the ash in this work was 3-4 %. For process economics and from the phosphorus extraction point, as high phosphorus content as possible in the ash is preferable. Higher phosphorus content can be accomplished by mixing sludge with a fuel with lower ash content than demolition wood, co-combustion with a fuel with higher phosphorus content than demolition wood, or by increasing the percentage of sewage sludge in the fuel mixture. Still, a higher proportion of sludge in the mixture would require a higher dry matter content of the sludge in order to get proper combustion conditions. It is primarily bottom ash that is suitable for phosphorus extraction using Easy Mining Sweden's method. If fly ash are to be used for phosphorus extraction, an optimization of the dissolution conditions is required, which was not included in this project. In this project, phosphorus is extracted as ammonium phosphate. The purity of ammonium phosphate is very high, which means that unwanted substances and heavy metals in sewage sludge will not be returned to contaminate fields.

  • 288.
    Cairns, Andrew G.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Vazquez-Romero, Ana
    Mahdi-Moein, Mohammad
    Ådén, Jörgen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Elmore, Charles S.
    Takano, Akihiro
    Arakawa, Ryosuke
    Varrone, Andrea
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Schou, Magnus
    Increased Brain Exposure of an Alpha-Synuclein Fibrillization Modulator by Utilization of an Activated Ester Prodrug Strategy2018Inngår i: ACS Chemical Neuroscience, ISSN 1948-7193, E-ISSN 1948-7193, Vol. 9, nr 11, s. 2542-2547Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Previous work in our laboratories has identified a series of peptidomimetic 2-pyridone molecules as modulators of alpha-synuclein (α-syn) fibrillization in vitro. As a first step toward developing molecules from this scaffold as positron emission tomography imaging agents, we were interested in evaluating their blood-brain barrier permeability in nonhuman primates (NHP) in vivo. For this purpose, 2-pyridone 12 was prepared and found to accelerate α-syn fibrillization in vitro. Acid 12, and its acetoxymethyl ester analogue 14, were then radiolabeled with 11C (t1/2 = 20.4 min) at high radiochemical purity (>99%) and high specific radioactivity (>37 GBq/μmol). Following intravenous injection of each compound in NHP, a 4-fold higher radioactivity in brain was observed for [11C]14 compared to [11C]12 (0.8 vs 0.2 SUV, respectively). [11C]14 was rapidly eliminated from plasma, with [11C]12 as the major metabolic product observed by radio-HPLC. The presented prodrug approach paves the way for future development of 2-pyridones as imaging biomarkers for in vivo imaging of α-synuclein deposits in brain.

  • 289.
    Calderon, Blanca
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Univ Alicante, Dept Chem Engn, San Vicente del Raspeig Rd S-N, Alicante 03690, Spain.
    Lundin, Lisa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Aracil, Ignacio
    Fullana, Andres
    Study of the presence of PCDDs/PCDFs on zero-valent iron nanoparticles2017Inngår i: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 169, s. 361-368Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Studies show that nanoscale zero-valent iron (nZVI) particles enhance the formation of chlorinated compounds such as polychlorinated dioxins and furans (PCDD/Fs) during thermal processes. However, it is unclear whether nZVI acts as a catalyst for the formation of these compounds or contains impurities, such as PCDD/Fs, within its structure. We analyzed the presence of PCDD/Fs in nZVI particles synthesized through various production methods to elucidate this uncertainty. None of the 2,3,7,8-substituted congeners were found in the commercially-produced nZVI, but they were present in the laboratory synthesized nZVI produced through the borohydride method, particularly in particles synthesized from iron (III) chloride rather than from iron sulfate. Total PCDD/F WHO-TEQ concentrations of up to 35 pg/g were observed in nZVI particles, with hepta-and octa-chlorinated congeners being the most abundant. The reagents used in the borohydride method were also analyzed, and our findings suggest that FeCl3 effectively contains PCDD/Fs at concentrations that could explain the concentrations observed in the nZVI product. Both FeCl3 and nZVI showed a similar PCDD/F patterns with slight differences. These results suggest that PCDD/Fs might transfer from FeCl3 to nZVI during the production method, and thus, care should be taken when employing certain nZVI for environmental remediation.

  • 290. Cano, A.
    et al.
    Lartundo-Rojas, L.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Reguera, E.
    Contribution to the coordination chemistry of transition metal nitroprussides: a cryo-XPS study2019Inngår i: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 43, nr 12, s. 4835-4848Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The series of coordination polymers under investigation was formed by the assembly of a pentacyanonitrosylferrate(ii) anionic block, [Fe(CN)(5)NO](2-), through monovalent and divalent transition metal ions, e.g. Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Ag+. For divalent ions, the resulting materials have a 3D porous framework with attractive features for applications in gas storage and separation, as electroactive solids, light-driven molecular magnets, and so on; in this study, we report the results obtained for a series of coordination polymers using the cryogenic X-ray photoelectron spectroscopy (cryo-XPS) data; comprehensive details regarding their coordination chemistries were obtained from the acquired spectra in addition to their comparison with the structural and spectroscopic information obtained from other techniques. The results discussed herein are original and contribute towards the understanding of the electronic structures and related properties for this family of coordination polymers. This series of solids was found to be highly susceptible to strong damage induced by X-ray beams throughout the conventional XPS experiment; therefore, the analysis was conducted under cryogenic conditions.

  • 291. Cano, A.
    et al.
    Rodríguez-Hernández, J.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Reguera, E.
    Intercalation of pyrazine in layered copper nitroprusside: synthesis, crystal structure and XPS study2019Inngår i: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 273, s. 1-10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hybrid inorganic–organic solids form an interesting family of functional materials, where their functionalities are determined by both, the inorganic and organic building blocks. This study reports the intercalation of pyrazine in 2D copper nitroprusside, the crystal structure of the resulting hybrid solid and explores the scope of cryogenic X-ray photoelectron spectroscopy (XPS) to shed light on its electronic structure. In this material, the pyrazine molecule appears coordinated to Cu atoms from neighboring layers, to form the columns in the resulting 3D porous framework. Its crystal structure was solved and refined from the corresponding XRD powder pattern. XPS data, recorded under cryogenic conditions, provided fine details on the electronic structure of this hybrid solid. The binding energy values for the ligand atoms and the involved metals show a definite correlation with the structural data and FT-IR spectra. When XPS spectra were recorded at room temperature, a significant sample decomposition was observed. Three possible mechanisms for the sample damage during the XPS experiment are considered. The hybrid material under study is representative of a wide series of nanoporous solids obtained by intercalation of organic pillars between 2D inorganic solids.

  • 292. Cao, Lin-Ying
    et al.
    Zheng, Ziye
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ren, Xiao-Min
    Andersson, Patrik L.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Guo, Liang-Hong
    Structure-dependent activity of polybrominated diphenyl ethers and their hydroxylated metabolites on estrogen related receptor gamma: in vitro and in silico study2018Inngår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 52, nr 15, s. 8894-8902Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 293.
    Caraballo, Remi
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, Mikael
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Fysiologisk kemi.
    Nilsson, Stefan K.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Fysiologisk kemi.
    Ericsson, Madelene
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Fysiologisk kemi.
    Qian, Weixing
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Tran, Nam Phuong Nguyen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kindahl, Tomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Svensson, Richard
    Uppsala, Sweden.
    Saar, Valeria
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Fysiologisk kemi.
    Artursson, Per
    Uppsala, Sweden.
    Olivecrona, Gunilla
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Fysiologisk kemi.
    Enquist, Per-Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Elofsson, Mikael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Structure-activity relationships for lipoprotein lipase agonists that lower plasma triglycerides in vivo2015Inngår i: European Journal of Medicinal Chemistry, ISSN 0223-5234, E-ISSN 1768-3254, Vol. 103, s. 191-209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The risk of cardiovascular events increases in individuals with elevated plasma triglyceride (TG) levels, therefore advocating the need for efficient TG-lowering drugs. In the blood circulation, TG levels are regulated by lipoprotein lipase (LPL), an unstable enzyme that is only active as a non-covalently associated homodimer. We recently reported on a N-phenylphthalimide derivative (1) that stabilizes LPL in vitro, and moderately lowers triglycerides in vivo (Biochem. Biophys. Res. Common. 2014, 450, 1063). Herein, we establish structure activity relationships of 51 N-phenylphthalimide analogs of the screening hit 1. In vitro evaluation highlighted that modifications on the phthalimide moiety were not tolerated and that lipophilic substituents on the central phenyl ring were functionally essential. The substitution pattern on the central phenyl ring also proved important to stabilize LPL However, in vitro testing demonstrated rapid degradation of the phthalimide fragment in plasma which was addressed by replacing the phthalimide scaffold with other heterocyclic fragments. The in vitro potency was retained or improved and substance 80 proved stable in plasma and efficiently lowered plasma TGs in vivo. 2015 The Authors. Published by Elsevier Masson SAS.

  • 294.
    Carlsson, Marcus
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Synthesis and optical characterization of optical power limiting platinum(II) acetylides2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Interactions between light and a molecule can result in reversible or irreversible changes in properties of both the light and the molecule. Of the many known interactions, nonlinear absorption is a process in which an intense light signal, for instance from a laser, can be moderated. This can be manifested either in a marked lowering of the light’s intensity or in reductions in fluctuations of its intensity. Such an effect is often termed ‘optical power limiting’ (OPL).

    High power lasers can be very dangerous since their high intensity can damage or destroy eyes and optical sensors. However, there are currently no adequate protective measures against lasers that cover the entire visible region and there is an increasing demand for new or improved OPL materials. Some of the most promising optical power limiting materials are substances that combine nonlinear optical properties with high transparency in normal light, but after activation by a laser beam, their light transmittance falls extremely rapidly via so-called self-activating mechanisms. The platinum(II) acetylides comprise one class of compounds with such properties.

    In this study, various OPL Pt(II) acetylides were synthesized and their nonlinear optical properties were characterized. The emphasis of the work was on preparation of the compounds, but in order to design organoplatinum chromophores for OPL, attempts were also made to obtain insight into the mechanisms of nonlinear absorption.

    The work was divided into two main parts. In the first the goal was to find compounds that are good optical limiters in solution. The possibility of isolating the chromophore site by dendron shielding and the effects of incorporating a thiophene ring into the organic molecular system were also explored. In addition, a new route for synthesizing these compounds was developed. The second part was focused on incorporating the most interesting compounds into solid materials. The preparation and characterization of Pt(II) acetylides with molecular groups for covalent attachment to a silica matrix via the solution gel approach is described.

  • 295.
    Carlsson, Sofia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Installation of a hydride generation system coupled to atomic absorption spectrometry in Vientiene, Laos PDR - Determination of arsenic in water samples 2012Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Until now, the possibility for the personnel at the National University of Lao PDR (NUOL) to perform analysis of arsenic in drinking water as well as water used for agriculture has been limited to indication sticks, giving only a vague indication of the presence and levels of arsenic. Due to the lack of adequate and sensitive analytical instruments the levels of arsenic are relatively unknown in Lao People Democratic Republic (Lao PDR). A simple method of analyzing arsenic in water is using atomic absorption spectroscopy (AAS) coupled to a hydride generation system (HG). In support of this project, an HG with an AAS-oven has been delivered and installed at the inorganic lab at NUOL. The system has been optimized and tested and the personnel at the university have been instructed and trained in how to use the system. Sampling and analysis were supposed to be executed although this part of the project encountered many problems and could not be performed in a satisfactory way. Problems mainly came from lack of material, i.e. distilled water, and knowledge as well as monsoon weather conditions making the sampling impossible.

  • 296.
    Carlsson, Sofia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Surface Characterization ofGram-Negative Bacteria andtheir Vesicles: Using Fourier Transform Infrared Spectroscopy andDynamic Light Scattering2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 297.
    Carlén, Simon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Identifying Sources and Ecological Risks of Polycyclic Aromatic Hydrocarbons in Polluted Fiber Enriched Sediments from the Bothnian Sea2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 298.
    Cavka, Adnan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Alriksson, Björn
    Processum Biorefinery Initiative AB, SE-891 22 Örnsköldsvik, Sweden.
    Ahnlund, Maria
    Umeå Plant Science Center, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
    Jönsson, Leif J
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Effect of sulfur oxyanions on lignocellulose-derived fermentation inhibitors2011Inngår i: Biotechnology and Bioengineering, ISSN 0006-3592, E-ISSN 1097-0290, Vol. 108, nr 11, s. 2592-2599Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent results show that treatments with reducing agents, including the sulfur oxyanions dithionite and hydrogen sulfite, efficiently improve the fermentability of inhibitory lignocellulose hydrolysates, and that the treatments are effective when the reducing agents are added in situ into the fermentation vessel at low temperature. In the present investigation, dithionite was added to medium with model inhibitors (coniferyl aldehyde, furfural, 5-hydroxymethylfurfural, or acetic acid) and the effects on the fermentability with yeast were studied. Addition of 10 mM dithionite to medium containing 2.5 mM coniferyl aldehyde resulted in a nine-fold increase in the glucose consumption rate and a three-fold increase in the ethanol yield. To investigate the mechanism behind the positive effects of adding sulfur oxyanions, mixtures containing 2.5 mM of a model inhibitor (an aromatic compound, a furan aldehyde, or an aliphatic acid) and 15 mM dithionite or hydrogen sulfite were analyzed using mass spectrometry (MS). The results of the analyses, which were performed by using UHPLC-ESI-TOF-MS and UHPLC-LTQ/Orbitrap-MS/MS, indicate that the positive effects of sulfur oxyanions are primarily due to their capability to react with and sulfonate inhibitory aromatic compounds and furan aldehydes at low temperature and slightly acidic pH (such as 25°C and pH 5.5).

  • 299.
    Cavka, Adnan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Guo, Xiang
    Tang, Shui-Jia
    Winestrand, Sandra
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jönsson, Leif J
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Hong, Feng
    Production of bacterial cellulose and enzyme from waste fiber sludge2013Inngår i: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 6, nr 25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Bacterial cellulose (BC) is a highly crystalline and mechanically stable nanopolymer, which has excellent potential as a material in many novel applications, especially if it can be produced in large amounts from an inexpensive feedstock. Waste fiber sludge, a residue with little or no value, originates from pulp mills and lignocellulosic biorefineries. A high cellulose and low lignin content contributes to making the fiber sludge suitable for bioconversion, even without a thermochemical pretreatment step. In this study, the possibility to combine production of BC and hydrolytic enzymes from fiber sludge was investigated. The BC was characterized using field-emission scanning electron microscopy and X-ray diffraction analysis, and its mechanical properties were investigated.

    Results: Bacterial cellulose and enzymes were produced through sequential fermentations with the bacterium Gluconacetobacter xylinus and the filamentous fungus Trichoderma reesei. Fiber sludges from sulfate (SAFS) and sulfite (SIFS) processes were hydrolyzed enzymatically without prior thermochemical pretreatment and the resulting hydrolysates were used for BC production. The highest volumetric yields of BC from SAFS and SIFS were 11 and 10 g/L (DW), respectively. The BC yield on initial sugar in hydrolysate-based medium reached 0.3 g/g after seven days of cultivation. The tensile strength of wet BC from hydrolysate medium was about 0.04 MPa compared to about 0.03 MPa for BC from a glucose-based reference medium, while the crystallinity was slightly lower for BC from hydrolysate cultures. The spent hydrolysates were used for production of cellulase with T. reesei. The cellulase activity (CMCase activity) in spent SAFS and SIFS hydrolysates reached 5.2 U/mL (87 nkat/mL), which was similar to the activity level obtained in a reference medium containing equal amounts of reducing sugar.

    Conclusions: It was shown that waste fiber sludge is a suitable raw material for production of bacterial cellulose and enzymes through sequential fermentation. The concept studied offers efficient utilization of the various components in fiber sludge hydrolysates and affords a possibility to combine production of two high value-added products using residual streams from pulp mills and biorefineries. Cellulase produced in this manner could tentatively be used to hydrolyze fresh fiber sludge to obtain medium suitable for production of BC in the same biorefinery.

  • 300.
    Cavka, Adnan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jönsson, Leif J
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Detoxification of lignocellulosic hydrolysates using sodium borohydride2013Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 136, s. 368-376Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Addition of sodium borohydride to a lignocellulose hydrolysate of Norway spruce affected the fermentability when cellulosic ethanol was produced using Saccharomyces cerevisiae. Treatment of the hydrolysate with borohydride improved the ethanol yield on consumed sugar from 0.09 to 0.31 g/g, the balanced ethanol yield from 0.02 to 0.30 g/g, and the ethanol productivity from 0.05 to 0.57 g/(L×h). Treatment of a sugarcane bagasse hydrolysate gave similar results, and the experiments indicate that sodium borohydride is suitable for chemical in-situ detoxification. The model inhibitors coniferyl aldehyde, p-benzoquinone, 2,6-dimethoxybenzoquinone, and furfural were efficiently reduced by treatment with sodium borohydride, even under mild reaction conditions (20°C and pH 6.0). While addition of sodium dithionite to pretreatment liquid from spruce improved enzymatic hydrolysis of cellulose, addition of sodium borohydride did not. This result indicates that the strong hydrophilicity resulting from sulfonation of inhibitors by dithionite treatment was particularly important for alleviating enzyme inhibition.

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