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  • 1. Abdullah, Muhammad Imran
    et al.
    Janjua, Muhammad Ramzan Saeed Ashraf
    Mahmood, Asif
    Ali, Sajid
    Ali, Muhammad
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Quantum Chemical Designing of Efficient Sensitizers for Dye Sensitized Solar Cells2013Ingår i: Bulletin of the Korean Chemical Society (Print), ISSN 0253-2964, E-ISSN 1229-5949, Vol. 34, nr 7, s. 2093-2098Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Density functional theory (DFT) was used to determine the ground state geometries of indigo and new design dyes (IM-Dye-1 IM-Dye-2 and IM-Dye-3). The time dependant density functional theory (TDDFT) was used to calculate the excitation energies. All the calculations were performed in both gas and solvent phase. The LUMO energies of all the dyes were above the conduction band of TiO2, while the HOMOs were below the redox couple (except IM-Dye-3). The HOMO-LUMO energy gaps of new design dyes were smaller as compared to indigo. All new design dyes were strongly red shifted as compared to indigo. The improved light harvesting efficiency (LHE) and free energy change of electron injection Delta G(inject) of new designed sensitizers revealed that these materials would be excellent sensitizers. The broken coplanarity between the benzene near anchoring group having LUMO and the last benzene attached to TPA unit in all new design dyes consequently would hamper the recombination reaction. This theoretical designing will the pave way for experimentalists to synthesize the efficient sensitizers for solar cells.

  • 2.
    Abiodun Daramola, Olamide
    et al.
    Centre for Chemico- and Biomedicinal Research (CCBR), Department of Chemistry, Faculty of Science, Rhodes University, Grahamstown, South Africa; Department of Chemical and Physical Sciences, Faculty of Natural Science, Walter Sisulu University, Private Bag XI, Mthatha, South Africa.
    Bazibuhe Safari, Justin
    Centre for Chemico- and Biomedicinal Research (CCBR), Department of Chemistry, Faculty of Science, Rhodes University, Grahamstown, South Africa; Department of Pharmacy, Faculty of Pharmaceutical Sciences and Public Health, Official University of Bukavu, Bukavu, Democratic Republic Congo.
    Adeniyi, Kayode Omotayo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Siwe-Noundou, Xavier
    Department of Pharmaceutical Sciences, School of Pharmacy, Sefako Makgatho Health Sciences University, Gauteng, Pretoria, South Africa.
    Margaret Kirkpatrick Dingle, Laura
    Biomedical Biotechnology Research Unit (BioBRU), Department of Biochemistry and Microbiology, Faculty of Science, Rhodes University, Grahamstown, South Africa.
    Lesley Edkins, Adrienne
    Biomedical Biotechnology Research Unit (BioBRU), Department of Biochemistry and Microbiology, Faculty of Science, Rhodes University, Grahamstown, South Africa.
    Foster Tseki, Potlaki
    Department of Chemical and Physical Sciences, Faculty of Natural Science, Walter Sisulu University, Private Bag XI, Mthatha, South Africa.
    Werner Maçedo Krause, Rui
    Centre for Chemico- and Biomedicinal Research (CCBR), Department of Chemistry, Faculty of Science, Rhodes University, Grahamstown, South Africa.
    Biocompatible liposome and chitosan-coated CdTe/CdSe/ZnSe multi-core-multi-shell fluorescent nanoprobe for biomedical applications2024Ingår i: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, E-ISSN 1873-2666, Vol. 454, artikel-id 115714Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cadmium telluride (CdTe) semiconductor quantum dots (QDs) are brightly luminescent nanocrystals that have emerged as a new class of fluorescent probes for in vivo bioimaging and theranostic applications. CdTe QDs toxicity to normal human cells is minimized by coating with a less toxic ZnS and ZnSe shell forming a core–shell nanostructure. However, coating with ZnS or ZnSe shell is insufficient to prevent the leaching of toxic Cd metal ions. To further minimize toxicity, thiol dual capped CdTe/CdSe/ZnSe multi-core-multi-shell quantum dots were coated with nanoliposome or liposome vesicles (CdTe/CdSe/ZnSe@liposome) and chitosan nanoparticles (CdTe/CdSe/ZnSe@ChitNPs) and their biocompatibility on HeLa and Vero cells were investigated. Different spectroscopic and microscopic techniques were used to elucidate nanocomposites' optical, morphological, and physicochemical properties. The coating of CdTe/CdSe/ZnSe multi-core-multi-shell quantum dots were conducted at different formulations (F1, F2 and F3) and results from the fluorescence studies show that F3 demonstrated the best interaction for both liposome and ChitNPs composite. Exposure to 12 h UV illumination studies also reveals that CdTe/CdSe/ZnSe@liposome shows an enhancement in fluorescence compared to CdTe/CdSe/ZnSe@ChitNPs. The cytotoxicity of the formulations towards HeLa and Vero cells also depicted minimal toxicity compared to CdTe/CdSe/ZnSe QDs that shows much higher toxicity (IC50 = 0.09381 mg/ml). It was further observed that liposome coated multi-core-multi-shell QDs@F2 demonstrated lower toxicity (IC50 = 0.4364 mg/ml) compared to ChitNPs coated multi-core-multi-shell QDs@F2 (IC50 = 0.1618 mg/ml). Results from the florescence imaging studies reveal that CdTe/CdSe/ZnSe-multi-core-multi-shell QDs liposomes and ChitNPs composite retained most of their fluorescence and properties and could easily be tracked in cells and visualized around the nucleus. This indicates the successful internalization of the QDs in the cytosol. Therefore, these results shows that coating CdTe multi-core-mutli-shell QDs with liposomes and ChitNPs produce better biocompatibility compared to uncoated multi-core–shell QDs. However, liposome coated CdTe/CdSe/ZnSe multi-core-multi-shell quantum dots show better optical properties, photostability and biocompatibility compared to CdTe/CdSe/ZnSe multi-core-multi-shell quantum dots with ChitNPs coating. These particles therefore show good promise in cell-labelling and drug delivery studies.

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  • 3. Accinelli, Cesare
    et al.
    Saccà, Maria Ludovica
    Batisson, Isabelle
    Fick, Jerker
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mencarelli, Mariangela
    Grabic, Roman
    Removal of oseltamivir (Tamiflu) and other selected pharmaceuticals from wastewater using a granular bioplastic formulation entrapping propagules of Phanerochaete chrysosporium2010Ingår i: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 81, nr 3, s. 436-43Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The capacity of the ligninolytic fungus Phanerochaete chrysosporium to degrade a wide variety of environmentally persistent xenobiotics has been largely reported in the literature. Beside other factors, one barrier to a wider use of this bioremediation fungus is the availability of effective formulations that ensure easy preparation, handling and application. In this series of laboratory experiments, we evaluated the efficiency of a granular bioplastic formulation entrapping propagules of P. chrysosporium for removal of four selected pharmaceuticals from wastewater samples. Addition of inoculated granules to samples of the wastewater treatment plant of Bologna significantly increased the removal of the antiviral drug oseltamivir (Tamiflu), and the antibiotics, erythromycin, sulfamethoxazol, and ciprofloxacin. Similar effects were also observed in effluent water. Oseltamivir was the most persistent of the four active substances. After 30d of incubation, approximately two times more oseltamivir was removed in bioremediated wastewater than controls. The highest removal efficiency of the bioplastic formulation was observed with the antibiotic ciprofloxacin. Microbiological DNA-based analysis showed that the bioplastic matrix supported the growth of P. chrysosporium, thus facilitating its adaptation to unusual environment such as wastewater.

  • 4. Acharya, Shravan S.
    et al.
    Easton, Christopher D.
    McCoy, Thomas M.
    Spiccia, Leone
    Ohlin, C. André
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. School of Chemistry, Monash University, Clayton, Australia.
    Winther-Jensen, Bjorn
    Diverse composites of metal-complexes and PEDOT facilitated by metal-free vapour phase polymerization2017Ingår i: Reactive & functional polymers, ISSN 1381-5148, E-ISSN 1873-166X, Vol. 116, s. 101-106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Abstract Oxidative polymerization for the manufacture of conducting polymers such as poly(3,4-ethylenedioxy-thiophene) has traditionally employed iron(III) salts. Demonstrated in this study is vapour phase polymerization of 3,4-ethylenedio- xythiophene using a metal-free oxidant, ammonium persulfate, leading to films with an estimated conductivity of 75 S/cm. Additionally, a route for embedding active transition metal complexes into these poly(3,4-ethylenedioxythiophene)/-poly(styrene-4-sulfonate) (PEDOT/PSS) films via vapour assisted complexation is outlined. Here, the vapour pressure of solid ligands around their melting temperatures was exploited to ensure complexation to metal ions added into the oxidant mixture prior to polymerization of PEDOT. Four composite systems are discussed, viz. PEDOT/PSS embedded with tris(8-hydroxyquinolinato)cobalt(III), tris(2,2-bipyridine)cobalt(II), tris(1,10- phenanthroline)cobalt(II) and tris(8-hyd-roxyquinolinato)aluminium(III). Using these composites, electrochemical reduction of nitrite to ammonia with a faradaic efficiency of 61% was reported.

  • 5. Acharya, Shravan
    et al.
    Winther-Jensen, Bjorn
    Spiccia, Leone
    Ohlin, André C.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rates of water exchange in 2,2'-bipyridine and 1,10-phenanthroline complexes of CoII and MnII2017Ingår i: Australian journal of chemistry (Print), ISSN 0004-9425, E-ISSN 1445-0038, Vol. 70, nr 6, s. 751-754Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The rates and activation parameters of water exchange at pH 3.0 have been determined using variable temperature 17O NMR spectroscopy for four CoII complexes and one MnII complex: [Co(bpy)(H2O)4]2+, [Co(bpy)2 (H2O)2]2+, [Co(phen)-(H2O)4]2+, [Co(phen)2 (H2O)2]2+, and [Mn(bpy)(H2O)4]2+ (bpy = 2,2′-bipyridyl and phen = 1,10-phenanthroline). Substitution of aquo ligands with 1,10-phenanthroline or 2,2′-bipyridyl leads to an increase in the rate of exchange in the manganese complexes, from k298 (1.8 ± 0.1) × 107 s-1 for [Mn(H2O)6]2+ to (7.2 ± 0.3) × 107 s-1 for [Mn(phen)2 (H2O)2]2+, whereas the trends are more complex for the cobalt complexes. We have used the new data in conjunction with literature data for similar complexes to analyse the effect of M–OH2 distance and degree of substitution.

  • 6.
    Addario, Barbara
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Huang, Shenghua
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sauer, Uwe
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Backman, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Crystallization and preliminary X-ray analysis of the Entamoeba histolytica α-actinin-2 rod domain2011Ingår i: Acta Crystallographica. Section F: Structural Biology and Crystallization Communications, ISSN 1744-3091, E-ISSN 1744-3091, Vol. 67, nr 10, s. 1214-1217Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    -Actinins form antiparallel homodimers that are able to cross-link actin filaments. The protein contains three domains: an N-terminal actin-binding domain followed by a central rod domain and a calmodulin-like EF-hand domain at the C-terminus. Here, crystallization of the rod domain of Entamoeba histolytica -actinin-2 is reported; it crystallized in space group P212121, with unit-cell parameters a = 47.8, b = 79.1, c = 141.8 Å. A Matthews coefficient VM of 2.6 Å3 Da-1 suggests that there are two molecules and 52.5% solvent content in the asymmetric unit. A complete native data set extending to a d-spacing of 2.8 Å was collected on beamline I911-2 at MAX-lab, Sweden.

     

  • 7.
    Adediran, Gbotemi A.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Liem-Nguyen, Van
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Song, Yu
    Schaefer, Jeffra K.
    Slcyllberg, Ulf
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Microbial Biosynthesis of Thiol Compounds: Implications for Speciation, Cellular Uptake, and Methylation of Hg(II)2019Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 53, nr 14, s. 8187-8196Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellular uptake of inorganic divalent mercury (Hg(II)) is a key step in microbial formation of neurotoxic methylmercury (MeHg), but the mechanisms remain largely unidentified. We show that the iron reducing bacterium Geobacter sulfurreducens produces and exports appreciable amounts of low molecular mass thiol (LMM-RSH) compounds reaching concentrations of about 100 nM in the assay medium. These compounds largely control the chemical speciation and bioavailability of Hg(II) by the formation of Hg(LMM-RS)<INF><INF><INF>2</INF></INF> </INF>complexes (primarily with cysteine) in assays without added thiols. By characterizing these effects, we show that the thermodynamic stability of Hg(II)-complexes is a principal controlling factor for Hg(II) methylation by this bacterium such that less stable complexes with mixed ligation involving LMM-RSH, OH-, and Cl- are methylated at higher rates than the more stable Hg(LMM-RS)<INF>2</INF> complexes. The Hg(II) methylation rate across different Hg(LMM-RS)<INF>2</INF> compounds is also influenced by the chemical structure of the complexes. In contrast to the current perception of microbial uptake of Hg, our results adhere to generalized theories for metal biouptake based on metal complexation with cell surface ligands and refine the mechanistic understanding of Hg(II) availability for microbial methylation.

  • 8.
    Adeniyi, Omotayo
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Osmanaj, Blerina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Chemistry, University of Prishtina, Prishtina, Republic of Kosovo.
    Manavalan, Gopinathan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Berisha, Avni
    Department of Chemistry, University of Prishtina, Prishtina, Republic of Kosovo.
    Tesfalidet, Solomon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Reagentless impedimetric immunosensor for monitoring of methotrexate in human blood serum using multiwalled carbon nanotube@polypyrrole/polytyramine film electrode2024Ingår i: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 268, nr Part 1, artikel-id 125316Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ensuring effective monitoring of methotrexate (MTX) levels in the bloodstream of cancer patients undergoing high-dose methotrexate chemotherapy is crucial to prevent potentially harmful side effects. However, the absence of portable analytical devices suitable for point-of-care bedside monitoring has presented a significant obstacle to achieving real-time MTX monitoring. In this study, we developed an impedimetric immunosensor that doesn't require reagents for measuring MTX levels in undiluted human blood serum. This reagentless approach simplifies the assay process, enabling rapid and straightforward MTX quantification. The immunosensor transducer was fabricated by electrodepositing conductive network of porous multiwalled carbon nanotube@polypyrrole/polytyramine on screen-printed gold microchip electrode (SP–Au/MWCNT70@PPy-PTA). Polyclonal anti-MTX antibodies were immobilized on the film, acting as the immunorecognition element. Non-specific binding was prevented by blocking the transducer interface with denatured bovine serum albumin (dBSA) fibrils, resulting in SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA film electrode. When MTX binds to the SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA interface, the film conductance and electron transfer resistance changes. This conductivity attenuation allows for electrochemical impedimetric signal transduction without a redox-probe solution. The electrochemical impedance spectroscopy (EIS) results showed increased charge transfer resistance and phase angle as MTX concentrations increased. The SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA demonstrated high sensitivity, with a linear response from 0.02 to 20.0 μM and a detection limit of 1.93 nM. The detection limit was 50 times lower than the intended safe level of MTX in human serum. The immunosensor exhibited minimal cross-reactivity with endogenous MTX analogs and serum proteins. The SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA immunosensor presents a simple and rapid method for therapeutic drug monitoring compared to traditional immunoassay systems.

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  • 9.
    Adeniyi, Omotayo
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Osmanaj, Blerina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Chemistry, University of Prishtina, 10000 Prishtina, Kosovo.
    Manavalan, Gopinathan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, 20500, Finland.
    Avni, Berisah
    Department of Chemistry, University of Prishtina, 10000 Prishtina, Kosovo.
    Boily, Jean-Francois
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Tesfalidet, Solomon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Engineering of layered iron vanadate nanostructure for electrocatalysis: simultaneous detection of methotrexate and folinic acid in blood serum2023Ingår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, artikel-id 142538Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, nanostructure kazakhstanite-like iron vanadate (FexV3xOy.H2O) was synthesized and calcined at different temperatures (100-800 °C) in a nitrogen atmosphere. The material was used to modify screen-printed carbon electrodes to achieve an electrocatalytic effect on the surface. The relationship between calcination conditions and the catalytic performance of the electrode towards the oxidation of chemotherapeutic drugs, including methotrexate (MTX) and folinic acid (FA), was studied. Various spectroscopic, microscopic, and electrochemical methods were used to characterize the synthesized materials. The results show that calcination induces changes in the electronic structure, nanostructure morphology, electroactive surface area, and electrocatalytic performance of the material. Screen-printed carbon electrode modified with FexV3xOy calcinated at 450 °C (SPC/FexV3xOy-450) was used to develop a voltammetric sensor for the determination of MTX and FA in blood serum. The response of the SPC/FexV3xOy-450 towards the electrooxidation of MTX and FA was the highest in comparison to the bare SPC and SPC/FexV3xOy calcined at other temperatures. The SPC/FexV3xOy-450 exhibited a linear relationship over a wide concentration range: 0.005-200 µM for MTX and 0.05-200 µM for FA. The detection limit was 2.85 nM for MTX and 7.79 nM for FA. Compared to conventional methods, the SPC/FexV3xOy-450 sensor had a short response time (5 min) for simultaneous detection of MTX and FA without signal interferences from coexisting electroactive compounds. The accurate and precise determination of MTX in the presence of FA confirmed the potential clinical applications of SPC/FexV3xOy-450 for therapeutic drug monitoring during chemotherapy.

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  • 10. Adnan, Muhammad
    et al.
    Iqbal, Javed
    Bibi, Shamsa
    Hussain, Riaz
    Akhtar, Muhammad Nadeem
    Rashid, Muhammad Abid
    Eliasson, Bertil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ayub, Khurshid
    Fine Tuning the Optoelectronic Properties of Triphenylamine Based Donor Molecules for Organic Solar Cells2017Ingår i: Zeitschrift fur physikalische Chemie (Munchen. 1991), ISSN 0942-9352, Vol. 231, nr 6, s. 1127-1139Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Geometrical parameters, electronic structures and photophysical properties of three new triphenylamine (TPA) and diphenylamine (DPA) based electron donor materials M1-M3 (for organic solar cells) have been investigated through density functional theory (DFT) methods at the B3LYP/6-31G(d) level of the theory. TPA and DPA are used as donor moieties due to their electron donating ability while benzothiazole, cyanide and cyanomethylacetate (CMA) moieties have been taken as acceptor moieties. The time dependent-DFT (TD-DFT) method has been employed [TD-B3LYP/6-31G (d)] for the computation of excited state properties in the gas phase and in solvent (chloroform). The polarization continuum model is applied for calculations in the solvent phase. The designed molecules exhibited broad absorption in the visible and near infra-red region of spectrum with respect to a reference molecule "R" of a similar class of compounds. Based on reorganization energies calculations, these materials could act as excellent hole transport materials.

  • 11.
    Adolfsson, Dan E.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Synthesis of Ring-fused Peptidomimetics: Interacting with Amyloid Fibrils2020Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Parkinson's and Alzheimer's disease are the two most common neurological disorders in humans. Both conditions involve progressive death of neurons in the central nervous system, decline in bodily functions and eventually (and invariably), death. So far, no cure exists and the available treatments can only ease symptoms. Despite substantial investments in research, the biomolecular processes are still far from fully understood. However, both diseases are associated with formation of fibrillar protein aggregates called amyloid deposits. Whereas Alzheimer’s disease involves aggregation of the Tau and Amyloid β proteins, α-Synuclein fibrilization plays a key role in Parkinson's disease. Although they are chemically distinct, the deposits consist of protein fibres with similar morphology and fold. Small molecules, such as the thiazoline fused 2-pyridones herein presented, can interfere with the formation of amyloid fibres, or bind to them. Besides having potential for diagnostication and treatment, such small molecules constitute valuable tool compounds in future research, to unravel the mechanisms of amyloid formation and pathology. The first step towards successful treatment, diagnostication and prevention of Alzheimer's and Parkinson's disease is understanding the causes and underlying mechanisms better. This thesis narrates the synthesis and development of novel chemical structures: multi ring fused peptidomimetics with the ability to bind mature amyloid fibrils, consisting of α-Synuclein or Amyloid β. 

    The first project (articles I, III and VI) describes method development for the extension of bicyclic thiazolino 2-pyrdiones by fusion with aromatic nitrogen heterocycles, which enables the desired amyloid binding properties. Derivatisations of the newly generated central scaffold, and variation of the multiple attached substituents, were subsequently performed in efforts to improve binding strength and solubility, and gain selectivity towards certain fibrils. One of the most promising amyloid fibril binders was evaluated in a human cell line and in mice, and found to be protective against accelerator induced neurotoxicity. One pyrimidine fused compound moreover indicated potent inhibition of Amyloid b aggregation. The second project (articles II, IV and V) focuses on development of methods to modify the thiazoline ring. Ring opening induced by electrophiles generates N-alkenyl 2-pyridones but decreases amyloid binding potency. Introduction of a cyclobutane moiety fused with the thiazoline ring is better tolerated, and adds a terminal alkene moiety that can be exploited in future chemical modifications. Expansion of the five membered thiazoline ring to a six membered dihydrothiazine ring, equipped with a nitrophenyl substituent, provides compounds with enhanced fibril binding capacity, which further inhibits Amyloid β fibril formation in vitro. Taken together, the synthetic methodologies allow construction and late stage modification of complex fused heterocycles, with several points of variation. Thus, the developed methods may be of future value in our laboratories and elsewhere.

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  • 12.
    Adolfsson, Dan E.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Tyagi, Mohit
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Singh, Pardeep
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Deuschmann, Adrian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ådén, Jörgen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Gharibyan, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Jayaweera, Sanduni Wasana
    Lindgren, Anders E. G.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Olofsson, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Intramolecular Povarov Reactions for the Synthesis of Chromenopyridine fused 2-Pyridone Polyheterocycles Binding to α-Synuclein and Amyloid-β fibrils2020Ingår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 85, nr 21, s. 14174-14189Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    A BF3×OEt2 catalyzed intramolecular Povarov reaction was used to synthesize a library of 15 chromenopyridine fused thiazolino-2-pyridone peptidomimetics. The reaction works with a range of O-alkylated salicylaldehydes and amino functionalized thiazolino-2-pyridones, to generate polyheterocycles with diverse substitution. The synthesized compounds were screened for their ability to bind α-synuclein and amyloid β fibrils in vitro. Analogs substituted with a nitro group bind to mature amyloid fibrils, and the activity moreover depends on the positioning of this functional group.

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  • 13.
    Adolfsson, Dan E.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Tyagi, Mohit
    Singh, Pardeep
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kaur, Amandeep
    Ådén, Jörgen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bharate, Jaideep B.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Enhanement of amyloid fibril binding by ring expansion of thiazolino fused 2-pyridone peptidomimeticsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Thiazolino fused 2-pyridones undergo thiazoline ring opening by reaction with 2-nitrobenzyl bromide through thi- oether attack, and base promoted fragmentation of the resulting sulfonium ions. Subsequent deprotonation of the benzylic carbon and intramolecular 1,4-addition leads to ring closure, generating dihydrothiazine fused 2-pyridones by net ring expansion of the thiazoline ring. Application of the ring expansion procedure to the pyridine and pyrimidine fused thiazolino 2-pyridones provided compounds with enhanced fibril binding activity.

  • 14.
    Adranno, Brando
    et al.
    Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16C, SE-10691 Stockholm, Sweden.
    Renier, Olivier
    Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16C, SE-10691 Stockholm, Sweden.
    Bousrez, Guillaume
    Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16C, SE-10691 Stockholm, Sweden.
    Paterlini, Veronica
    Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16C, SE-10691 Stockholm, Sweden.
    Baryshnikov, Glib V.
    Department of Science and Technology, Laboratory of Organic Electronics, Linköping University, SE-60174 Norrköping, Sweden.
    Smetana, Volodymyr
    Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16C, SE-10691 Stockholm, Sweden.
    Tang, Shi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ågren, Hans
    Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden.
    Metlen, Andreas
    The QUILL Research Centre and School of Chemistry and Chemical Engineering The Queen’s University of Belfast Belfast, Northern Ireland BT9 5AG, UK.
    Edman, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Anja-Verena, Mudring
    Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16C, SE-10691 Stockholm, Sweden; Intelligent Advanced Materials (iAM), Department of Biological and Chemical Engineering and iNANO, Aarhus University, 8000 Aarhus C, Denmark.
    Rogers, Robin D.
    Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16C, SE-10691 Stockholm, Sweden; The QUILL Research Centre and School of Chemistry and Chemical Engineering The Queen’s University of Belfast Belfast, Northern Ireland BT9 5AG, UK.
    The 8-hydroxyquinolinium cation as a lead structure for efficient color-tunable ionic small molecule emitting materials2023Ingår i: Advanced Photonics Research, ISSN 2699-9293, Vol. 4, nr 3, artikel-id 2200279Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Albeit tris(8-hydroxyquinolinato) aluminum (Alq3) and its derivatives are prominent emitter materials for organic lighting devices, and the optical transitions occur among ligand-centered states, the use of metal-free 8-hydroxyquinoline is impractical as it suffers from strong nonradiative quenching, mainly through fast proton transfer. Herein, it is shown that the problem of rapid proton exchange and vibration quenching of light emission can be overcome not only by complexation, but also by organization of the 8-hydroxyquinolinium cations into a solid rigid network with appropriate counter-anions (here bis(trifluoromethanesulfonyl)imide). The resulting structure is stiffened by secondary bonding interactions such as pi-stacking and hydrogen bonds, which efficiently block rapid proton transfer quenching and reduce vibrational deactivation. Additionally, the optical properties are tuned through methyl substitution from deep blue (455 nm) to blue-green (488 nm). Time-dependent density functional theory (TDFT) calculations reveal the emission to occur from which an unexpectedly long-lived S-1 level, unusual for organic fluorophores. All compounds show comparable, even superior photoluminescence compared to Alq3 and related materials, both as solids and thin films with quantum yields (QYs) up to 40-50%. In addition, all compounds show appreciable thermal stability with decomposition temperatures above 310 °C.

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  • 15.
    Adranno, Brando
    et al.
    Physical Materials Chemistry, Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden.
    Tang, Shi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Paterlini, Veronica
    Physical Materials Chemistry, Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden.
    Smetana, Volodymyr
    Physical Materials Chemistry, Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden; Intelligent Advanced Materials (iAM), Department of Biological and Chemical Engineering and iNANO, Aarhus University, 8000 Aarhus C, Denmark.
    Renier, Olivier
    Physical Materials Chemistry, Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden.
    Bousrez, Guillaume
    Physical Materials Chemistry, Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden; Intelligent Advanced Materials (iAM), Department of Biological and Chemical Engineering and iNANO, Aarhus University, 8000 Aarhus C, Denmark.
    Edman, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Mudring, Anja-Verena
    Physical Materials Chemistry, Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden; Intelligent Advanced Materials (iAM), Department of Biological and Chemical Engineering and iNANO, Aarhus University, 8000 Aarhus C, Denmark.
    Broadband white-light-emitting electrochemical cells2023Ingår i: Advanced Photonics Research, ISSN 2699-9293, Vol. 4, nr 5, artikel-id 2200351Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Emerging organic light-emitting devices, such as light-emitting electrochemical cells (LECs), offer a multitude of advantages but currently suffer from that most efficient phosphorescent emitters are based on expensive and rare metals. Herein, it is demonstrated that a rare metal-free salt, bis(benzyltriphenylphosphonium)tetrabromidomanganate(II) ([Ph3PBn]2[MnBr4]), can function as the phosphorescent emitter in an LEC, and that a careful device design results in the fact that such a rare metal-free phosphorescent LEC delivers broadband white emission with a high color rendering index (CRI) of 89. It is further shown that broadband emission is effectuated by an electric-field-driven structural transformation of the original green-light emitter structure into a red-emitting structure.

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  • 16.
    Afvander, Åsa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Development of a working method for the study of a distillation process: Distillation of a multicomponent system2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
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  • 17.
    Aghbolagh, Mahdi Shahmohammadi
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Meynaq, Mohammad Yaser Khani
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shimizu, Kenichi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lindholm-Sethson, Britta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Aspects on mediated glucose oxidation at a supported cubic phase2017Ingår i: Bioelectrochemistry, ISSN 1567-5394, E-ISSN 1878-562X, Vol. 118, s. 8-13Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A supported liquid crystalline cubic phase housing glucose oxidase on an electrode surface has been suggested as bio-anode in a biofuel. The purpose of this investigation is to clarify some aspect on the mediated enzymatic oxidation of glucose in such a bio-anode where the mediator ferrocene-carboxylic acid and glucose were dissolved in the solution. The enzyme glucose oxidase was housed in the water channels of the mono-olein cubic phase. The system was investigated with cyclic voltammetry at different scan rates and the temperature was varied between 15 degrees C and 30 degrees C. The diffusion coefficient of the mediator and also the film resistance was estimated showing a large decrease in the mass-transport properties as the temperature was decreased. The current from mediated oxidation of glucose at the electrode surface increased with decreasing film thickness. The transport of the mediator in the cubic phase was the rate-limiting step in the overall reaction, where the oxidation of glucose took place at the outer surface of the cubic phase.

  • 18.
    Aglar, Öznur
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Design and synthesis of inhibitors of the ADP ribosylating toxin ExoS: Targeting the Type III Secretion System (T3SS) of Pseudomonas aeruginosa.2016Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
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  • 19.
    Agnemo, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten.
    Ligniners reaktioner med alkalisk väteperoxid1981Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Under alkaline conditions hydrogen peroxide can be used either as a 1ignin-degrading or a 1ignin-preserving bleaching agent. If heavy metal ions are present and/or silicate is absent in the reaction medium, hydrogen peroxide decomposes via hydroxyl radicals and superoxide ions to oxygen and water. These decomposition products are able to react for example with phenolic lignin structures and thereby cause a partial degradation of lignin. In such a system peroxide could act as a bleaching and delignifying agent at the same time and these properties can be utilized for the bleaching of chemical pulps.In order to elucidate the factors which influence the degradation of phenolic structures by oxidation with alkaline hydrogen peroxide the lignin model compounds-methylsyringyl alcohol was studied.By determining the first order reaction rate constants for the oxidation, the main results which were obtained indicate that phenolic lignin structures can be efficiently degraded especially if:A. The pH in the bleaching liquor is close to the pK -valueàfor hydrogen peroxide.B. The ionic strength in the bleaching medium is as high as possible.C. A fixed amount of heavy metal ions (manganese) is added to the bleaching liquor.In the presence of silicate and diethylentriaminepenta-acetic acid (DTPA) hydrogen peroxide is stabilized against decomposition. Under these conditions alkaline hydrogen peroxide is able to react only with lignin units containing conjugated carbonyl groups such as quinone, aryl-oe-carbonyl and cinnamaldehyd structures, leading to an elimination of the chromophoric structures without any substantial dissolution of lignin. In this part of work we have elucidated the kinetic behavior and the reaction products from lignin model compounds of the aryl-of- carbonyl and cinnamaldehyde types.1,2-Diarylpropan-1,3,-diol structures constitute an important building unit in native lignins. We have demonstrated that under hydrogen peroxide bleaching conditions the model compound 2,3--bis(4-hydroxy-3-methoxyphenyl)-3-ethoxy-propanol was converted to stilbenes, ûe. structures which when present in pulps may contribute to a rapid yellowing. The results obtained with model compounds under simulated lignin retaining bleaching conditions demonstrate that there are possibilities to improve the bleaching of mechanical pulps with hydrogen peroxide if:A. The remaining heavy metal ions complexed with DTPA are present in their lowest valence states.B. The concentration of hydroperoxy ions can be maintained at a high level at the lowest possible pH-value.

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  • 20. Agrawal, Ganesh Kumar
    et al.
    Job, Dominique
    Kieselbach, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Barkla, Bronwyn J.
    Chen, Sixue
    Deswal, Renu
    Luethje, Sabine
    Amalraj, Ramesh Sundar
    Tanou, Georgia
    Ndimba, Bongani Kaiser
    Cramer, Rainer
    Weckwerth, Wolfram
    Wienkoop, Stefanie
    Dunn, Michael J.
    Kim, Sun Tae
    Fukao, Yochiro
    Yonekura, Masami
    Zolla, Lello
    Rohila, Jai Singh
    Waditee-Sirisattha, Rungaroon
    Masi, Antonio
    Wang, Tai
    Sarkar, Abhijit
    Agrawal, Raj
    Renaut, Jenny
    Rakwal, Randeep
    INPPO Actions and Recognition as a Driving Force for Progress in Plant Proteomics: Change of Guard, INPPO Update, and Upcoming Activities2013Ingår i: Proteomics, ISSN 1615-9853, E-ISSN 1615-9861, Vol. 13, nr 21, s. 3093-3100Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    The International Plant Proteomics Organization (INPPO) is a non-profit organization whose members are scientists involved or interested in plant proteomics. Since the publication of the first INPPO highlights in 2012, continued progress on many of the organization's mandates/goals has been achieved. Two major events are emphasized in this second INPPO highlights. First, the change of guard at the top, passing of the baton from Dominique Job, INPPO founding President to Ganesh Kumar Agrawal as the incoming President. Ganesh K. Agrawal, along with Dominique Job and Randeep Rakwal initiated the INPPO. Second, the most recent INPPO achievements and future targets, mainly the organization of first the INPPO World Congress in 2014, tentatively planned for Hamburg (Germany), are mentioned.

  • 21.
    Aguilar, Ximena
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Weise, Christoph
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sparrman, Tobias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wolf-Watz, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wittung-Stafshede, Pernilla
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Macromolecular crowding extended to a heptameric system: the co-chaperonin protein 102011Ingår i: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 50, nr 14, s. 3034-3044Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Experiments on monomeric proteins have shown that macromolecular crowding can stabilize toward heat perturbation and also modulate native-state structure. To assess the effects of macromolecular crowding on unfolding of an oligomeric protein, we here tested the effects of the synthetic crowding agent Ficoll 70 on human cpn10 (GroES in E. coli), a heptameric protein consisting of seven identical β-barrel subunits assembling into a ring. Using far-UV circular dichroism (CD), tyrosine fluorescence, nuclear magnetic resonance (NMR), and cross-linking experiments, we investigated thermal and chemical stability, as well as the heptamer-monomer dissociation constant, without and with crowding agent. We find that crowding shifts the heptamer-monomer equilibrium constant in the direction of the heptamer. The cpn10 heptamer is both thermally and thermodynamically stabilized in 300 mg/mL Ficoll 70 as compared to regular buffer conditions. Kinetic unfolding experiments show that the increased stability in crowded conditions, in part, is explained by slower unfolding rates. A thermodynamic cycle reveals that in presence of 300 mg/mL Ficoll the thermodynamic stability of each cpn10 monomer increases by over 30%, whereas the interfaces are stabilized by less than 10%. We also introduce a new approach to analyze the spectroscopic data that makes use of multiple wavelengths: this provides robust error estimates of thermodynamic parameters.

  • 22. Aguilera, Adriana Freites
    et al.
    Tolvanen, Pasi
    Heredia, Shuyana
    Muñoz, Marta González
    Samson, Tina
    Oger, Adrien
    Verove, Antoine
    Eränen, Kari
    Leveneur, Sebastien
    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, Åbo-Turku, Finland.
    Salmi, Tapio
    Epoxidation of fatty acids and vegetable oils assisted by microwaves catalyzed by a cation exchange resin2018Ingår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 57, nr 11, s. 3876-3886Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Epoxidation of oleic acid and cottonseed oil was conducted in a semibatch reactor with in-situ-formed percarboxylic acid (peracetic acid or perpropionic acid), using hydrogen peroxide as an oxidizing agent and carboxylic acid (acetic acid or propionic acid) as oxygen carriers. Amberlite IR-120 was implemented as the catalyst. The system was comprised of a loop reactor, where the mixture was pumped through a single-mode cavity in which microwave irradiation was introduced. A heat exchanger was integrated into the system to replace microwave heating, to compare the results obtained via microwave heating versus conventional heating. The catalyst loading effect was studied, as well as the influence of microwave irradiation and the implementation of the SpinChem rotating bed reactor (RBR), in hopes of decreasing the influence of the internal mass transfer. The application of microwave irradiation results in an improvement of the reaction yield in the absence of a catalyst.

  • 23. Aguilera, Adriana Freites
    et al.
    Tolvanen, Pasi
    Oger, Adrien
    Eränen, Kari
    Leveneur, Sébastien
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku-Åbo, Finland.
    Salmi, Tapio
    Screening of ion exchange resin catalysts for epoxidation of oleic acid under the influence of conventional and microwave heating2019Ingår i: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 94, nr 9, s. 3020-3031Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: For many chemical systems, it is of great importance to find a durable, active and efficient catalyst that improves the process performance. Epoxidation of oleic acid with peracetic acid (Prilezhaev oxidation) was carried out in an isothermal loop reactor in the presence of heterogeneous catalysts. The kinetic experiments conducted under microwave heating (MW) were compared with identical experiments carried out under conventional (conductive/convective) heating. Extensive screening of heterogeneous catalysts was conducted and the influence of microwave irradiation on the reaction kinetics was studied. Several ion exchange resins were screened to explore their applicability and activity in the epoxidation of oleic acid. The perhydrolysis reaction (peracetic acid formed in situ from acetic acid and H2O2) was promoted with the use of various solid acid catalysts: Amberlite IR-120, Amberlyst 15, Smopex®, Dowex 50x8-100, Dowex 50x8-50, Dowex 50x2-100 and Nafion™.

    Results: From the selected group of catalysts, Dowex 50-x8100 and Dowex 50x8-50 produced the highest yield of epoxidized oil. Only minor differences in the reactant conversion and the product yield were found in the experiments carried out under microwave exposure compared to the conventionally heated experiments in the presence of several ion exchange resins.

    Conclusions: The catalytic effect was much more prominent than the microwave effect, because the solid acid catalysts enhanced the slow step of the process, the perhydrolysis of acetic acid. The catalytic effect was very dominant and a considerable improvement of the oleic acid conversion and the epoxide yield was observed in the presence of the top-performing catalysts.

  • 24. Ahlgren, Joakim
    et al.
    De Brabandere, Heidi
    Reitzel, Kasper
    Rydin, Emil
    Gogoll, Adolf
    Waldeback, Monica
    Sediment phosphorus extractants for phosphorus-31 nuclear magnetic resonance analysis: A quantitative evaluation2007Ingår i: Journal of Environmental Quality, ISSN 0047-2425, E-ISSN 1537-2537, Vol. 36, nr 3, s. 892-898Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of pre-extractant, extractant, and post-extractant on total extracted amounts of P and organic P compound groups measured with 31 P nuclear magnetic resonance (P-31-NMR) in lacustrine sediment was examined. The main extractants investigated were sodium hydroxide (NaOH) and sodium hydroxide ethylenediaminetetraacetic acid (NaOH-EDTA) with bicarbonate buffered dithionite (BD) or EDTA as pre-extractants. Post extractions were conducted using either NaOH or NaOH-EDTA, depending on the main extractant. Results showed that the most efficient combination of extractants for total P yield was NaOH with EDTA as pre-extractant, yielding almost 50% more than the second best procedure. The P compound groups varying the most between the different extraction procedures were polyphosphates and pyrophosphates. NaOH with BD as pre-extractant was the most efficient combination for these compound groups.

  • 25.
    Ahlgren, Ulf
    Umeå universitet, Medicinska fakulteten, Umeå centrum för molekylär medicin (UCMM).
    Imaging shows insulin-producing cells in diabetes2013Ingår i: TrAC. Trends in analytical chemistry, ISSN 0165-9936, E-ISSN 1879-3142, Vol. 44, s. III-IIIArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 26.
    Ahlkvist, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Formic and Levulinic Acid from Cellulose via Heterogeneous Catalysis2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The chemical industry of today is under increased pressure to develop novel green materials, bio-fuels as well as sustainable chemicals for the chemical industry. Indeed, the endeavour is to move towards more eco-friendly cost efficient production processes and technologies and chemical transformation of renewables has a central role considering the future sustainable supply of chemicals and energy needed for societies. In the Nordic countries, the importance of pulping and paper industry has been particularly pronounced and the declining European demand on these products as a result of our digitalizing world has forced the industry to look at alternative sources of revenue and profitability. In this thesis, the production of levulinic and formic acid from biomass and macromolecules has been studied. Further, the optimum reaction conditions as well as the influence of the catalyst and biomass type were also discussed.

    Nordic sulphite and sulphate (Kraft) cellulose originating from two Nordic pulp mills were used as raw materials in the catalytic synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice used in this study was a macro-porous, cationic ion-exchange resin, Amberlyst 70, for which the optimal reaction conditions leading to best yields were determined. Cellulose from Nordic pulp mills were used as raw materials in the catalytic one-pot synthesis of ‘green’ levulinic and formic acid. The kinetic experiments were performed in a temperature range of 150–200 °C and an initial substrate concentration regime ranging from 0.7 to 6.0 wt %. It was concluded that the most important parameters in the one-pot hydrolysis of biomass were the reaction temperature, initial reactant concentration, acid type as well as the raw material applied. The reaction route includes dehydration of glucose to hydroxymethylfurfural as well as its further rehydration to formic and levulinic acids. The theoretical maximum yield can hardly be obtained due to formation of humins. For this system, maximum yields of 59 mol % and 68 mol % were obtained for formic and levulinic acid, respectively. The maximum yields were separately obtained in a straight-forward conversion system only containing cellulose, water and the heterogeneous catalyst. These yields were achieved at a reaction temperature of 180 °C and an initial cellulose intake of 0.7 wt % and belong to the upper range for solid catalysts so far presented in the literature.

    The reaction network of the various chemical species involved was investigated and a simple mechanistic approach involving first order reaction kinetics was developed. The concept introduces a one-pot procedure providing a feasible route to green platform chemicals obtained via conversion of coniferous soft wood pulp to levulinic and formic acids, respectively. The model was able to describe the behaviour of the system in a satisfactory manner (degree of explanation 97.8 %). Since the solid catalyst proved to exhibit good mechanical strength under the experimental conditions applied here and a one-pot procedure providing a route to green platform chemicals was developed. A simplified reaction network of the various chemical species involved was investigated and a mechanistic approach involving first order reaction kinetics was developed.

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  • 27.
    Ahlkvist, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ajaikumar, Samikannu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    One-pot catalytic conversion of Nordic pulp media into green platform chemicals2013Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 454, s. 21-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, both sulphite and sulphate (Kraft) cellulose from Nordic pulp mills were used as raw materials in the catalytic one-pot synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice was a macro-porous, cationic ion-exchange resin, Amberlyst 70. The optimal reaction conditions were determined and the influence of various gas atmospheres was investigated. The maximum yields of 53% formic acid and 57% of levulinic acid were separately obtained in a straight-forward conversion system only containing cellulose, water and the heterogeneous catalyst. The concept introduces a one-pot procedure providing a feasible route to green platform chemicals obtained via conversion of coniferous soft wood pulp to levulinic and formic acids, respectively.

  • 28.
    Ahlkvist, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mäki-Arvela, Päivi
    Åbo Akademi.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akademi University, Process Chemistry Centre, Åbo Akademi University, Industrial Chemistry & Reaction Engineering., Finland.
    Macro-molecules as a source of levulinic acid2014Ingår i: International Review of Chemical Engineering, ISSN 2035-1755, Vol. 16, nr 1, s. 44-58Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The production of levulinic acid from biomass and macromolecules has been reviewed. It was concluded that the most important parameters in the one-pot hydrolysis of biomass, also including dehydration of glucose to hydroxymethylfurfural as well as its further rehydration to formic and levulinic acids, respectively, are the reaction temperature, initial reactant concentration, acid type as well as the raw material applied. The theoretical maximum yield can hardly be obtained due to formation of humins. Further, the optimum reaction conditions as well as the influence of the catalyst and biomass type are also discussed.

  • 29.
    Ahlkvist, Johan
    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.
    Wärnå, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Salmi, Tapio
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Reaction Network upon One-pot Catalytic Conversion of Pulp2013Ingår i: / [ed] Sauro Pierucci, Jiří J. Klemeš, AIDIC - associazione italiana di ingegneria chimica, 2013, Vol. 32, s. 649-654Konferensbidrag (Refereegranskat)
    Abstract [en]

    Nordic sulphite and sulphate (Kraft) cellulose originating from Nordic pulp mills were used as raw materials in the catalytic synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice used in this study was a macro-porous, cationic ion-exchange resin Amberlyst 70 for which the optimal reaction conditions leading to best yields were determined. For this system, maximum yields of 53 mol-% and 57 mol-% were obtained for formic and levulinic acid, respectively. The reaction network of the various chemical species involved was investigated and a simple mechanistic approach involving first order reaction kinetics was developed. The prototype model was able to describe the behaviour of the system in a satisfactory manner.

  • 30.
    Ahlkvist, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Catalytic conversion of lignocellulosic materials2010Konferensbidrag (Övrigt vetenskapligt)
  • 31.
    Ahlkvist, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wärnå, Johan
    Åbo Akademi.
    Salmi, Tapio
    Åbo Akademi.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Experimental and Kinetic Modelling Studies upon Conversion of Nordic Pulp into Levulinic AcidManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In this paper, sulphite cellulose from a Swedish pulp mill was applied as the raw material upon catalytic, one-pot synthesis of green platform chemicals – levulinic and formic acids. Cationic ion-exchange resin, Amberlyst 70, was the catalyst of choice and the optimal reaction conditions leading to best yields were determined. The kinetic experiments were performed in a temperature range of 180–200 °C and an initial substrate concentration regime ranging from 0.7 to 6.0 wt %. For this system, maximum theoretical yields of around 59 mol % and 68 mol % were obtained for formic and levulinic acid, respectively. These yields were achieved at a reaction temperature of 180 °C and an initial cellulose intake of 0.7 wt %. A simplified reaction network of the various chemical species involved was investigated and a mechanistic approach involving first order reaction kinetics was developed. The model was able to describe the behaviour of the system in a satisfactory manner (degree of explanation 97.8 %). Since the solid catalyst proved to exhibit good mechanical strength under the experimental conditions applied here, the concept introduces a one-pot procedure providing a route to green platform chemicals from coniferous soft wood pulp to produce levulinic and formic acids, respectively.

  • 32.
    Ahlkvist, Johan
    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, Process Chemistry Centre, Åbo Akademi University,Turku, Finland.
    Salmi, Tapio
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University,Turku, Finland.
    Heterogeneously catalyzed conversion of nordic pulp to levulinic and formic acids2016Ingår i: Reaction Kinetics, Mechanisms and Catalysis, ISSN 1878-5190, E-ISSN 1878-5204, Vol. 119, nr 2, s. 415-427Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Herein, one-pot conversion of cellulose to platform chemicals, formic and levulinic acids was demonstrated. The catalyst selected was an affordable, acidic ion-exchange resin, Amberlyst 70, whereas the cellulose used was sulfite cellulose delivered by a Swedish pulp mill. Furthermore, in an attempt to better understand the complex hydrolysis network of the polysaccharide, kinetic experiments were carried out to pinpoint the optimal reaction conditions with an initial substrate concentration of 0.7–6.0 wt% and a temperature range of 180–200 °C. Higher temperatures could not be used due to the limitations in the thermal stability of the catalyst. Overall, maximum theoretical yields of 59 and 68 mol% were obtained for formic and levulinic acid, respectively. The parameters allowing for the best performance were reaction temperature of 180 °C and initial cellulose concentration of 0.7 wt%. After studying the behavior of the system, a simplified reaction network in line with a mechanistic approach was developed and found to follow first order reaction kinetics. A satisfactory fit of the model to the experimental data was achieved (97.8 % degree of explanation). The catalyst chosen exhibited good mechanical strength under the experimental conditions and thus, a route providing green platform chemicals from soft wood pulp from coniferous trees (mixture of Scots Pine and Norway Spruce) was demonstrated.

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  • 33. Aid, T.
    et al.
    Hyvarinen, S.
    Vaher, M.
    Koel, M.
    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, Åbo-Turku, Finland.
    Saccharification of lignocellulosic biomasses via ionic liquid pretreatment2016Ingår i: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 92, s. 336-341Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The current work focuses on the pretreatment efficiency of ILs combined with heat for woody biomass consisting of spruce, birch and pine as well as winter wheat straw. The latter was investigated as a comparison and with the aim to enhance its digestibility during enzymatic hydrolysis whereby the influence of IL-treatment to cellulose resistance for hydrolysis was investigated. Considering the wood species, the most common and industrially important wood species in Northern Europe were chosen in the present work and the goal was to obtain fermentable sugars and their degradation product, i.e. 5-hydroxymethylfurfural (5-HMF), which is known valuable platform chemical. Further, the differences in the yields of IL-obtainable carbohydrates between these species were studied. The highest sugar yields were obtained to glucose in the case of spruce and arabinose in the case of pine sapwood, 12.07 and 7.72 mmol/L, respectively. The highest 5-HMF yield was obtained for spruce heartwood (9.18 mmol/L) with longer treatment time, such as 100h. However, regarding woody biomass, the present work was focused more on the study and analysis of the IL-containing liquid part, wood hydrolysate, after IL-treatment aiming to answer the analysis challenges related to this fraction.

  • 34.
    Aigner, Harald
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Characterization of FtsH proteases in the annual plant Arabidopsis thaliana2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Background FtsH is an ATP-dependent membrane-bound metalloprotease. A. thaliana contains 12 FtsH proteases localized in membranes of chloroplasts and mitochondria where they form homo- or hetero-hexameric complexes. FtsH11 – the main subject of this thesis – is located in the chloroplast envelope.

     

    Methods

    • Field studies with A. thaliana to determine Darwinian fitness. A growth under outdoor conditions often allows discovering of phenotypes that are unascertainable in the controlled environment of growth chambers.
    • Proteomic methods to discover fragments of substrate proteins (limited proteolysis) and changes in the proteome of FtsH protease deficient mutants.

     

    Results ftsh11 has increased amount of: RuBisCO activase, several Calvin cycle enzymes, two enzymes involved in starch synthesis and some chaperons. Some of those enzymes have been identified as possible substrates of FtsH11. Under long photoperiods ftsh11 develops a chlorotic phenotype accompanied by decreasing NADP+/NADPH ratio and increase of ROS damaged proteins. 

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    Characterization of FtsH proteases in the annual plant Arabidopsis thaliana
  • 35.
    Aigner, Harald
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Comparison of hypothetical 3D-structures of Arabidopsis thaliana FtsH Proteases with the aim to predict FtsH complex formationManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In Arabidopsis thaliana 12 metallo proteases of the FtsH family are located in the organellar membranes of chloroplasts and mitochondria. While it is known for the Arabidopsis FtsH proteases FtsH1, 2, 5 and 8 to form a hetero–oligomeric, hexameric complex in the chloroplast thylakoid membrane and for FtsH3 and 10 in the inner membrane of mitochondria, no data are available for the remaining (low abundant) FtsH proteases . We compared the sequence identity of amino acids predicted to be relevant in complex formation of FtsH proteases in order to predict additional hetero-oligomeric FtsH complexes. Focus was set on FtsH11 and FtsH4, two subunits that might form a complex in mitochondria. 

  • 36.
    Aigner, Harald
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Searching for substrates of the metallo protease FtsH11 of Arabidopsis thaliana using N-terminal proteomics2012Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    FtsH11 is a membrane-bound metalloprotease localized in mitochondria and in the chloroplast envelope of Arabidopsis thaliana. An ftsh11 knock-out mutant has been shown to develop a chlorotic phenotype in prolonged photoperiods. The proteome of the ftsh11 chloroplast revealed increased abundance of several Calvin cycle enzymes, chaperones and some other proteins, however, none of those proteins could be verified to be an FtsH11 substrate (Harald Aigner, Raik Wagner, Lars L.E. Sjögren, Holger Eubel, A. Harvey Millar, Adrian K. Clarke, Christiane Funk, 2012, manuscript submitted). Here, we have used positional proteomics to identify peptides that report FtsH11 processing events. In this work we were able to identify seven chloroplast-localized proteins that are processed in wild type, but not in ftsh11.  

  • 37.
    Aisenbrey, Christopher
    et al.
    Institut de Chimie Universit0 Louis Pasteur Strasbourg—CNRS, UMR 7177 4, Rue Blaise Pascal, 67000 Strasbourg (France); Max-Planck-Institut f>r Biochemie Am Klopferspitz 18A, 82152 Martinsried (Germany).
    Cusan, Monica
    Lambotte, Stephan
    Jasperse, Pieter
    Georgescu, Julia
    Harzer, Ulrike
    Bechinger, Burkhard
    Specific Isotope Labeling of Colicin E1 and B Channel Domains For Membrane Topological Analysis by Oriented Solid-State NMR Spectroscopy2008Ingår i: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 9, nr 6, s. 944-951Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An approach is presented to selectively label the methionines of the colicin E1 and B channel domains, each about 200 residues in size, and use them for oriented solid-state NMR investigations. By combining site-directed mutagenesis, bacterial overexpression in a methionine auxotroph E. coli strain and biochemical purification, quantitative amounts of the proteins for NMR structural investigations were obtained. The proteins were selectively labeled with 15N at only one, or at a few, selected sites. Multidimensional heteronuclear correlation high-resolution NMR spectroscopy and mass spectrometry were used to monitor the quality of isotopic labeling. Thereafter the proteins were reconstituted into oriented phospholipid bilayers and investigated by proton-decoupled 15N solid-state NMR spectroscopy. The colicin E1 thermolytic fragment that carries a single 15N methionine within its hydrophobic helix 9 region exhibited 15N resonances that are characteristic of helices that are oriented predominantly parallel to the membrane surface at low temperature, and a variety of alignments and conformations at room temperature. This suggests that the protein can adopt both umbrella and pen-knife conformations.

  • 38.
    Ajaikumar, Samikannu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ahlkvist, Johan
    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.
    Kordas, K
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Piispankatu 8, FIN-20500, Turku/Åbo, Finland.
    Oxidation of α-pinene over gold containing bimetallic nanoparticles supported on reducible TiO2 by DPU method2011Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 392, nr 1-2, s. 11-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of bimetallic catalysts Au–M (where M = Cu, Co and Ru) were supported on a reducible TiO2 oxide via deposition-precipitation (DP) method with a slow decomposition of urea as the precipitating agent. The characteristic structural features of the prepared materials were characterized by various physico-chemical techniques such as X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). XPS results indicated the formation of alloyed bimetallic particles on the TiO2 support. TEM results confirmed the fine dispersion of metal nanoparticles on the support with an average particle size in the range of 3–5 nm. An industrially important process, oxy-functionalization of α-pinene was carried out over the prepared bimetallic heterogeneous catalysts under liquid phase conditions. Reaction parameters such as the reaction time, temperature, and the effect of solvent were studied for optimal conversion of α-pinene into verbenone. The major products obtained were verbenone, verbenol, α-pinene oxide and alkyl-pinene peroxide. The activity of the catalysts followed the order; AuCu/TiO2 > AuCo/TiO2 > Cu/TiO2 > Au/TiO2 > AuRu/TiO2. Upon comparison of the various catalysts, AuCu/TiO2 was found to be an active and selective catalyst towards the formation of verbenone. The temperature, nature of the catalysts and the choice of solvents greatly influenced the reaction rate.

  • 39.
    Ajaikumar, Samikannu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Chemistry, Anna University, Guindy, Chennai, India.
    Backiaraj, Muthaiah
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Turku/Åbo, Finland.
    Pandurangan, Arumugam
    Transesterification of diethyl malonate with n-butanol over HPWA/MCM-41 molecular sieves2013Ingår i: Journal of porous materials, ISSN 1380-2224, E-ISSN 1573-4854, Vol. 20, nr 4, s. 951-959Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mesoporous Si-MCM-41 and Al-MCM-41 (Si/Al = 100) materials were synthesized via a hydrothermal method. Three different ratios (10, 20 and 30 wt%) of heteropoly tungstic acid (HPWA) was loaded on Si-MCM-41 by wet impregnation techniques. The characteristic structural features of the prepared materials were studied by various physico-chemical techniques such as X-ray diffraction (XRD), Nitrogen physisorption (BET), temperature programmed desorption of ammonia (TPD) and transmission electron microscopy (TEM). Transesterification of diethyl malonate (DEM) with n-butanol under autogeneous conditions in a temperature range from 50 to 125 °C was selected as the test reaction for the as synthesized materials. The reactants were fed with various mole ratios in order to determine the optimal feed composition leading to maximum yields of transesterified products. The results indicated that the conversion of diethylmalonate depends on the HPWA concentration on the support, temperature, reaction time and mole ratio of the reactants. Further, the catalytic efficiency of HPWA/MCM-41 was compared with that of Al-MCM-41. The solid acid HPWA/MCM-41 catalysts have several advantages in comparison to conventional mineral acid catalysts which are heterogeneous, eco-friendly, highly active and selective in the formation of transesters.

  • 40.
    Akhtar, Sohel
    et al.
    School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India.
    Bala, Sukhen
    School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India.
    De, Avik
    School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India.
    Das, Krishna Sundar
    School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India.
    Adhikary, Amit
    School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India.
    Jyotsna, Shubhra
    Physical & Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune, India.
    Poddar, Pankaj
    Physical & Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune, India.
    Mondal, Raju
    School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India.
    Designing Multifunctional MOFs Using the Inorganic Motif [Cu33-OH)(μ-Pyz)] as an SBU and Their Properties2018Ingår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 19, nr 2, s. 992-1004Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a continuation of our interest in pyrazole-based multifunctional metal–organic frameworks (MOFs), we report herein the construction of a series of Cu(II) MOFs using pyrazole and various 5-substituted isophthalic acids. The central theme is to generate MOFs using the crystal engineering strategy of spacer and node; however, for the node we have introduced a well-known inorganic motif, a [Cu3(μ3-OH)(μ-Pyz)3] unit. The appearance of the SBU in five MOFs confirms the robustness and reproducibility of the motif with some interesting structures of various dimensionality ranging from 1D helical and 2D herringbone grid to a complex 3D framework. The deployment of bent acids brings chirality via helicity in the system, as further confirmed by solid-state CD spectra. A detailed investigation of the porous MOFs reveals their importance as zeolite analogues for environment remediation. MOF-1–MOF-5 show some interesting photodegradation of harmful organic dyes. MOF-4 and MOF-5 show impressive selective CO2 gas sorption properties. Furthermore, magnetic properties associated with the trinuclear and hexanuclear SBUs of MOF-1 and MOF-3–MOF-5 have also been investigated.

  • 41.
    Al Mamoon, Hassan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Evaluation of the separation capacity of different GC columns for tetra- to octachlorinated PCDD/Fs2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
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  • 42.
    Alam, Md Khorshed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Fabrication of surface enhanced Raman spectroscopy (SERS) active substrates based on vertically aligned nitrogen doped carbon nanotube forest2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis work describes the fabrication and surface enhanced Raman spectroscopy (SERS) characterization of vertically aligned nitrogen (N) doped multi walled carbon nanotube (MWCNT) forests coated by silver (Ag) and gold (Au) nanoparticles. In the present work, the CNT forests were grown from a catalyst metal layer by the chemical vapor deposition (CVD) process at temperature of 800 oC and a physical vapor deposition (PVD) and annealing processes were applied subsequently for the evaporation and diffusion of noble metal nanoparticles on the forest.

    Transistor patterning of 20, 50 and 100 μm were made onto the silicon-oxide (SiO2) wafers through the photolithography process with and without depositing a thickness of 10 nm titanium (Ti) buffer layer on the Si-surfaces. Iron (Fe) and cobalt (Co) were used together to deposite a thickness of 5 nm catalyst layer onto the Single Side Polished (SSP) wafers. As carbon and nitrogen precursor for the CNT growth was used pyridine. Two different treatment times (20 and 60 minutes) in the CVD process determined the CNT forest height. Scanning Electron Microscopy (SEM) imaging was employed to characterize the CNT forest properties and Ag and Au nanoparticle distribution along the CNT walls.

    The existence of “hot spots” created by the Ag and Au nanoparticles through the surface roughness and plasmonic properties was demonstrated by the SERS measurements. Accordingly, the peak intensity at wave number of 1076 cm-1 was picked up from each SERS spectra to establish the Ag- and Au-trend curves with different concentrations of 4-ATP solution. The SERS mapping was also carried out to study the Ag- and Au-coated CNT surface homogeneity and “hot spots” distribution on the CNT surface. The SERS enhancement factors (EF) were calculated by applying an analyte solution of ethanolic 4-ATP on the CNT surface. The calculated values of EF from Ag- and Au-coated CNT forests were 9×106 and 2.7×105 respectively. 

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  • 43.
    Alammar, Tarek
    et al.
    Department of Chemistry, College of Science, King Faisal University, P.O Box 400, Al-Ahsa, Saudi Arabia.
    Mudring, Anja-Verena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Department of Biological & Chemical Engineering, Intelligent Advanced Materials, Aarhus University, Aarhus, Denmark.
    Synthesis and exploration of Barium Stannate-Zirconate BaSn1-xZrxO3 (0 ≤ X ≤ 1) solid solutions as photocatalysts2024Ingår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 63, nr 14, s. 6132-6140Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Employing ionic liquid-assisted microwave synthesis and moderate heat treatment allows for the preparation of otherwise difficult-to-obtain perovskite-type BaSn1-xZrxO3 solid solutions (0 ≤ x ≤ 1). The impact of substituting Sn for the crystal structure, crystallinity, morphology, and photocatalytic performance was investigated. The obtained materials are characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and Raman and IR spectroscopy. SEM images show that the morphology of the samples varies from rods for x = 0, 0.2 to spherical for x = 0.5, 0.8, 1. Upon Zr for Sn substitution, the band gap changes from 3.1 to 5.0 eV as the valence and conduction bands move to lower and higher energies. The photocatalytic activities of the BaSn1-xZrxO3 samples in the hydroxylation of terephthalic acid (TA) follow the order BaSn0.5Zr0.5O3> BaSn0.8Zr0.2O3> BaSnO3> BaSn0.2Zr0.8O3> BaZrO3. The superior photocatalytic activity of BaSn0.5Zr0.5O3 can be attributed to the synergistically favorable combination of a suitable band structure, band gap size, and increased surface area-to-volume ratio, resulting in a diminished crystalline particle size unattainable from samples prepared via traditional synthetic routes or without ionic liquid.

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  • 44.
    Albers, Michael F
    et al.
    Department of Chemical Biology, Max Planck Institute for Molecular Physiology.
    Hedberg, Christian
    Amino acid building blocks for Fmoc solid-phase synthesis of peptides phosphocholinated at serine, threonine, and tyrosine2013Ingår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 78, nr 6, s. 2715-2719Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Phosphocholination of eukaryotic host cell proteins has recently been identified as a novel post-translational modification important for bacterial pathogenesis. Here, we describe the first straightforward synthetic strategy for peptides containing phosphocholinated serine, threonine, or tyrosine residues using preformed functional amino acid building blocks, fully compatible with standard Fmoc solid-phase peptide synthesis.

  • 45.
    Albers, Michael F
    et al.
    Department of Chemical Biology, Max-Planck Institute of Molecular Physiology.
    van Vliet, Bart
    Hedberg, Christian
    Amino acid building blocks for efficient Fmoc solid-phase synthesis of peptides adenylylated at serine or threonine2011Ingår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 13, nr 22, s. 6014-6017Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The first straightforward building block based (non-interassembly) synthesis of peptides containing adenylylated serine and threonine residues is described. Key features include final global acidolytic protective group removal as well as full compatibility with standard Fmoc solid-phase peptide synthesis (SPPS). The described Thr-AMP SPPS-building block has been employed in the synthesis of the Thr-adenylylated sequence of human GTPase CDC42 (Ac-SEYVP-T(AMP)-VFDNYGC-NH(2)). Further, we demonstrate proof-of-concept for the synthesis of an Ser-adenylylated peptide (Ac-GSGA-S(AMP)-AGSGC-NH(2)) from the corresponding adenylylated serine building block.

  • 46.
    Albers, Michael Franz
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Synthesis and investigation of bacterial effector molecules2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    During infections, bacterial microorganisms initiate profound interactions with mammalian host cells. Usually defense mechanisms of the host destroy intruding bacteria in rapid manner. However, many bacterial pathogens have evolved in a way to avoid these mechanisms. By use of effector molecules, which can be small organic molecules or proteins with enzymatic activity, the host is manipulated on a molecular level. Effectors mediating post-translational modifications (PTMs) are employed by many pathogens to influence the biological activity of host proteins. In the presented thesis, two related PTMs are investigated in detail: Adenylylation, the covalent transfer of an adenosine monophosphate group from adenosine triphosphate onto proteins, and phosphocholination, the covalent transfer of a phosphocholine moiety onto proteins. Over the past years, enzymes mediating these modifications have been discovered in several pathogens, especially as a mechanism to influence the signaling of eukaryotic cells by adenylylating or phosphocholinating small GTPases. However, the development of reliable methods for the isolation and identification of adenylylated and phosphocholinated proteins remains a vehement challenge in this field of research. This thesis presents general procedures for the synthesis of peptides carrying adenylylated or phosphocholinated tyrosine, threonine and serine residues. From the resulting peptides, mono-selective polyclonal antibodies against adenylylated tyrosine and threonine have been raised. The antibodies were used as tools for proteomic research to isolate unknown substrates of adenylyl transferases from eukaryotic cells. Mass spectrometric fragmentation techniques have been investigated to ease the identification of adenylylated proteins. Furthermore, this work presents a new strategy to identify adenylylated proteins. Additionally, small effector molecules are involved in the regulation of infection mechanisms. In this work, the small molecule LAI-1 (Legionella autoinducer 1) from the pathogen Legionella pneumophila, the causative agent of the Legionnaire’s disease, was synthesised together with its amino-derivatives. LAI-1 showed are a clear pharmacological effect on the regulation of the life cycle of L. pneumophila, initiating transmissive traits like motility and virulence. Furthermore, LAI-1 was shown to have an effect on eukaryotic cells as well. Directed motility of the eukaryotic cells was significantly reduced and the cytoskeletal architecture was reorganised, probably by interfering with the small GTPase Cdc42.

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  • 47.
    Albán Reyes, Diana Carolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå University.
    de Wit, Paul P.
    AkzoNobel Specialty Chemicals.
    Sundman, Ola
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Variation of the alkalisation conditions during the synthesis of a cellulose etherManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    We show the effect of simultaneous variation of i) the NaOH/AGU (anhydroglucose unit) stoichiometric ratio (r), ii) added [NaOH], and iii) mercerization time, on the degree of cellulose substitution (DS), and by-product formation including proportions of insoluble particles and unreacted chemicals, in the synthesis of carboxymethylcellulose (CMC), under conditions resembling those often used for production of non-ionic cellulose ethers and without the use of alcohols. The DS was found to increase when (r) was increased (range 1.0-1.3) and added [NaOH] was decreased (range 50-30%). However, such changes also favoured the formation of unwanted by-products. Decreased (r) and increased [NaOH] resulted in increased the quantities of insoluble particles and unreacted chemicals. In the CMC samples, DS of 0.18-0.7 was obtained. The measured solubility (46%-86%) was lower than expected for a given DS. This, along with a deviation of the substituent distribution from the statistical calculations, indicated a high heterogeneity in the samples. The substitution at hydroxyl positions within the AGU shows the order of < ≈ , and that substitution increases with (r). The relative importance of substitution at increases with an increased [NaOH].

  • 48.
    Albán Reyes, Diana Carolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Eliasson, Bertil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Karlsson, Leif
    AkzoNobel.
    de Wit, Paul
    AkzoNobel.
    Svedberg, Anna
    MoRe Research.
    Sundman, Ola
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Activation of dissolving celluloses pulp for viscose and cellulose ether production2016Ingår i: The 7th workshop on cellulose, regenerated cellulose and cellulose derivatives / [ed] Ola Sundman, Umeå ; Karlstad: Umeå university ; Karlstad university , 2016, s. 29-30Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Mercerisation of cellulose by alkali treatment is the most common procedure used to activate natural cellulose fibres into many commercial cellulosic materials. During mercerisation, the NaOH solution enters the cellulose fibres, transforming them into a swollen and a highly reactive material called alkali cellulose (Na-Cell). In case NaOH is completely washed out of the cellulose structure, Na-Cell turns into Cellulose II upon drying.

    Traditionally the cellulose is mercerised by suspending it in a 15-20 % NaOH solution. The result is a high (15-25 mol/mol) NaOH: Anhydroglucose  molar ratio (r) and mercerisation in these conditions have been extensively studied. However, in modern production of cellulose ethers, the mercerisation conditions are often very different. The main reason is that any excess of water and OH--ions used during the mercerisation can later react with different chemicals in the process, thus forming unwanted by-products e.g. methanol. One way to avoid this kind of side reaction is by using low-water-content mercerisation conditions, i.e. low (r) = 0.8-1.8 mol/mol and high NaOH concentration (45-55% w/w). The traditional mercerisation is a suspension process while the cellulose during the latter process, i.e low-water-content mercerisation conditions, remains quite “dry”. Thus, although the chemical reaction principles of activation of cellulose for both viscose and cellulose ethers processes are the same, the activation conditions used are often very different. Therefore, the different dependencies of process parameters as well as any similarities between the processes are interesting.

    The presentation summarises the findings presented in two papers which described the influence of the different parameters on the mercerisation/activation of softwood Sulphite dissolving pulp in viscose production conditions (Albán Reyes et al. 2016) and cellulose derivatives production conditions (Albán Reyes et al.) respectively. In the individual studies this has been done by analysing the degree of transformation (DoT) of dissolving pulp to Na-cellulose (or more correctly cellulose II after washing and upon drying) as a function of simultaneous variation of [NaOH], temperature, and reaction time varied using design of experiment. Also the (r) was varied for samples mercerised at dry conditions. A combination of Raman imaging and multivariate data analysis have been used to study the DoT to Cellulose II.

    It was found that the mercerisation under the different conditions was dependent on different parameters. For traditional mercerisation, on the one hand, the temperature was shown to be important for the DoT and showed negative correlation with the data, while [NaOH] showed a positive correlation. On the other hand, at low-water-content mercerisation conditions the (r) was overall most important while the temperature showed no statistical importance in a Partial least squares analysis. Traditional mercerisation gave much higher DoT than the low-water-content mercerisation. Thus,  the data for low-water-content mercerisation was further examined at the different (r). The same chemistry is always expected and the different influences of the parameters seen is understood and discussed in terms of the different physical reaction mechanisms.  

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  • 49.
    Albán Reyes, Diana Carolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden .
    Svedberg, Anna
    Eliasson, Bertil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sundman, Ola
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    The influence of different parameters on the mercerisation of cellulose for viscose production2016Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 2, s. 1061-1072Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A quantitative analysis of degree of transformation from a softwood sulphite dissolving pulp to alkalised material and the yield of this transformation as a function of the simultaneous variation of the NaOH concentration, denoted [NaOH], reaction time and temperature was performed. Samples were analysed with Raman spectroscopy in combination with multivariate data analysis and these results were confirmed by X-ray diffraction. Gravimetry was used to measure the yield. The resulting data were related to the processing conditions in a Partial Least Square regression model, which made it possible to explore the relevance of the three studied variables on the responses. The detailed predictions for the interactive effects of the measured parameters made it possible to determine optimal conditions for both yield and degree of transformation in viscose manufacturing. The yield was positively correlated to the temperature from room temperature up to 45 A degrees C, after which the relation was negative. Temperature was found to be important for the degree of transformation and yield. The time to reach a certain degree of transformation (i.e. mercerisation) depended on both temperature and [NaOH]. At low temperatures and high [NaOH], mercerisation was instantaneous. It was concluded that the size of fibre particles (mesh range 0.25-1 mm) had no influence on degree of transformation in viscose processing conditions, apparently due to the quick reaction with the excess of NaOH.

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  • 50.
    Albán Reyes, Diana Carolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Stridh, Kjell
    AkzoNobel, Stenungsund, Sverige.
    de Wit, Paul P.
    AkzoNobel, Arnhem, The Netherlands.
    Sundman, Ola
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Is there a diffusion of alkali in the activation of dissolving cellulose pulp at low NAOH stoichiometric excess?2019Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, nr 2, s. 1297-1308Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We conducted a quantitative study, following the degree of activation (i.e. the transformation to alkali cellulose, denoted as DoA) over time for dissolving cellulose pulp treated with different [NaOH] at low NaOH/anhydroglucose unit stoichiometric ratio (denoted as (r) ≤ 2.6). Our quantitative approach was based on Raman spectroscopy data, evaluated by partial least squares regression modelling. The results show strong influence of the (r) on DoA (increasing from DoA= 45% at (r) = 0.8, to DoA = 85% at (r) = 2.6), and its complex dependence on [NaOH]. At (r) = 0.8 the highest DoA (DoA ≳ 60%) was found at 30% [NaOH], while at (r) =1.3 it was found at 20% [NaOH] (DoA ≳ 80%). Although activation of cellulose happens in minutes at the studied temperature (30 °C), it was found that the reaction may be slow when a low (r) is used. A gradual increase of the DoA from ≈ 30% to ≈ 70% in time was seen when samples were activated with 30% [NaOH] at (r) = 0.8. At the same (r), a similar increase of DoA from ≈ 30 % to ≈ 60 % was also observed when 40% [NaOH] was used. Slow diffusion of NaOH through poorly swollen cellulose fibres is proposed as an explanation for this phenomenon. Lastly, solid-state CP/MAS NMR measurements suggest that at a fixed temperature, the Na-Cell allomorph mostly depends on [NaOH]. However, in the transition area between Na-Cell I and Na-Cell II, its influence might be affected by (r). 

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