Change search
Refine search result
1 - 47 of 47
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Arvidsson, Martin
    et al.
    Department of Psychology, Stockholm University, Sweden.
    Berglund, Birgitta
    Department of Psychology, Stockholm University, Sweden.
    Skedung, Lisa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Aikala, Maiju
    Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), Espoo, Finland.
    Danerlöv, Katrin
    Institute for Surface Chemistry (YTK), Stockholm, Sweden.
    Kettle, John
    Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), Espoo, Finland.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Multidimensional psychophysics: surface feel of printing paper as a function of physical propertiesManuscript (preprint) (Other academic)
  • 2.
    B. Kumar, Ramakrishnan
    et al.
    Karolinska institutet, Sverige.
    Zhu, Lin
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology.
    Hebert, Hans
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology. Karolinska institutet, Sverige.
    Jegerschöld, Caroline
    Karolinska institutet, Sverige.
    Method to Visualize and Analyze Membrane Interacting Proteins by Transmission Electron Microscopy2017In: Journal of Visualized Experiments, ISSN 1940-087X, E-ISSN 1940-087X, no 121, article id e55148Article in journal (Refereed)
    Abstract [en]

    Monotopic proteins exert their function when attached to a membrane surface, and such interactions depend on the specific lipid composition and on the availability of enough area to perform the function. Nanodiscs are used to provide a membrane surface of controlled size and lipid content. In the absence of bound extrinsic proteins, sodium phosphotungstate-stained nanodiscs appear as stacks of coins when viewed from the side by transmission electron microscopy (TEM). This protocol is therefore designed to intentionally promote stacking; consequently, the prevention of stacking can be interpreted as the binding of the membrane-binding protein to the nanodisc. In a further step, the TEM images of the protein-nanodisc complexes can be processed with standard single-particle methods to yield low-resolution structures as a basis for higher resolution cryoEM work. Furthermore, the nanodiscs provide samples suitable for either TEM or non-denaturing gel electrophoresis. To illustrate the method, Ca2+-induced binding of 5-lipoxygenase on nanodiscs is presented.

  • 3.
    Blute, Irena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Pugh, Robert J.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    van de Pas, John
    Callaghan, Ian
    Industrial manufactured silica nanoparticle sols. 2: Surface tension, particle concentration, foam generation and stability2009In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 337, no 1-3, p. 127-135Article in journal (Refereed)
    Abstract [en]

    Several earlier papers have revealed that several key parameters, such as hydrophobicity (contact angle), size, shape and degree of agglomeration, have an important influence on the behavior of particles at the air/water interface. However, the origin of foaming with particles is still not clear. In this article, we have tentatively related surface tension measurements and particle concentrations to the generation and stability of foam produced from industrial manufactured silica nanoparticle sols. Surprisingly, only slight reductions in surface tension were observed and the differences between the hydrophophilic and partially modified hydrophobic sols were small. However, in the case of the partially modified hydrophobic sol, the surface tension/concentration gradient was found to be pH and concentration responsive. Also, the greatest reduction in Surface tension was found to occur at low pH (in the region of the pH(pzc)) and could be related to the highest foamability (foam generation) as determined in our earlier publication [1. Blute, R.J. Pugh, J. van de Pas, I. Callaghan, Silica nanoparticle sols. 1. Surface chemical characterization and evaluation of the foam generation (foamability), J. Colloid Interface Sci. 313 (2007) 645-655]. Also, after centrifugation of the moderately hydrophobic modified concentrated sols, foaming tests carried out on the supernatant indicated that the particle concentration had a dominant influence on foamability and foam stability. Since only transient foams, with relatively short lifetimes, could be produced with these modified silica nanoparticles then (a) further surface modification or the reduction of pH to increase the Surface activity or (b) the addition of a cosurfactant Would be needed to increase the foamability and achieve foams with extended lifetimes.

  • 4.
    David, Lindström
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Galvanized steel in outdoor constructions - metal runoff, corrosion and patina formation2010Licentiate thesis, comprehensive summary (Other academic)
  • 5.
    Eriksson, Margareta
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Ozone decomposition in acidic solutionsManuscript (preprint) (Other academic)
  • 6.
    Eriksson, Margareta
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Östensson, Rasmus
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Bacteriological study of an aqueous solution with ozone and SDS or SDSperoxide2005In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336Article in journal (Other academic)
  • 7.
    Gerdin, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Silaborations of Unsaturated Compounds2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This thesis deals with the development of transition metal-catalyzed silaborations of 1,3-dienes and 1,6-enynes.

    The first part of the thesis describes the development of the enantioselective 1,4-silaboration of 1,3-cyclohexadiene. A number of chiral metal-ligand complexes were evaluated. Up to 82% enantiomeric excess was obtained using a catalyst system derived from Pt(acac)2 and a phosphoramidite ligand. The product formed was employed in allylborations of aldehydes, giving homo-allylic alcohols in good yields with good to moderate diastereoselectivity. In attempts to widen the scope of silaborations to include acyclic, terminally substituted 1,3-dienes, products from H-B exchange with, and H-Si addition to, the dienes were obtained.

    The second part describes the development of silaborative carbocyclization of 1,6-enynes. A Pd N-heterocylic carbene complex was found to be effective for the silaborative carbocyclization of unsubstituted enynes, giving the products in good to excellent yields. Employing terminally substituted enynes resulted in low or no yields.

    The last part describes investigations into the reaction mechanisms of the processes developed in the first part. It was found that the silylborane undergoes oxidative addition to a Pt(0) complex generated from Pt(acac)2 and DIBALH. After insertion of 1,3-cyclohexadiene into the Pt-B bond a π-allyl complex was observed experimentally. In the addition of silylborane to acyclic, terminally substituted, 1,3-dienes it was shown by deuterium labeling experiments that one diene loses a hydride via H-B exchange and that this hydride is then added to another diene via H-Si addition. A reaction mechanism was proposed for this process.

  • 8.
    Gil, Harveth
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Quantitative in situ analysis of initial atmospheric corrosion of copper induced by acetic acid.2007In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 154, no 5, p. 272-278Article in journal (Refereed)
    Abstract [en]

    The initial atmospheric corrosion of copper was investigated by means of a quantitative in situ analysis in an atmospherecontaining 120 ppb of acetic acid and 95% relative humidity using a quartz crystal microbalance (QCM) integrated with infraredreflection absorption spectroscopy (IRAS). Crystalline cuprous oxide (various structural forms of Cu2O) and hydrated copperacetate were detected as corrosion products during up to 100 h of exposure. The quantification of data was made possible throughan observed linear relationship between the absorbance of vibrations (IRAS)of both phases and the corresponding mass (QCM).The quantification of cuprous oxide was further supported by ex situ coulometric reduction of the corrosion products. The growthrate of cuprous oxide was initially very fast but almost zero after 20 h exposure where it reached an average thickness of13 ± 1 nm. Copper acetate exhibited a more constant growth rate. Atomic force microscopy showed a uniform growth of cuprousoxide with surface roughness that increased with time and localized formation of copper acetate. The quantified data are consistentwith a previously proposed model that involves proton- and acetate-induced dissolution of copper and subsequent precipitation ofcuprous oxide and copper acetate.

  • 9.
    Gustafsson, Åsa
    et al.
    KTH, Superseded Departments, Chemistry.
    Molera, Mireia
    KTH, Superseded Departments, Chemistry.
    Puigdomenech, Ignasi
    KTH, Superseded Departments, Chemistry.
    Study of Ni(II) sorption on chlorite - a fracture filling mineral in granites2004In: 28th Symposium on the Scientific Basis for Nuclear Waste Management held at the 2004 MRS Spring Meeting San Francisco, CA, APR 13-16, 2004, 2004, Vol. 824, p. 373-378Conference paper (Refereed)
    Abstract [en]

    Chlorite is an Fe(II)-containing phyllosilicate which is often present as a fracture filling mineral in e.g. granitic rocks. It may therefore be significant in influencing redox conditions and sorption processes in granitic groundwaters. The sorption properties of chlorite may therefore be important when modelling the migration of radionuclides under reducing conditions around nuclear waste repositories or in sites contaminated by mining waste. The sorption behaviour of Ni(II) onto a natural chlorite (Karlsborg, Sweden) was investigated using a batch technique. The effects of three different background electrolyte concentrations (0.01 M, 0.1 M and 0.5 M NaClO4) different pH values (ranging from 4 to 11) and different Ni(II) concentrations (10(-6) and 10(-8) M) were studied under anoxic conditions in a glove-box. Ni(II) solutions were spiked with 63 Ni and beta-Liquid scintillation counting (LSC) was used to determine the concentration of nickel in the bulk solution, allowing the calculation of solid-water distribution coefficients for the metal ion. The results of the sorption experiments show strong pH dependence at pH > 5, but the sorption is independent of ionic strength. The maximum adsorption is found in the pH range between 7 and 11 with K-d values approximate to10(3) cm(3)/g. A diffuse double layer model has been used to describe the experimental results.

  • 10.
    Hagfeldt, Anders
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry (closed 20110630).
    Boschloo, Gerrit
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Pettersson, Henrik
    Dye-Sensitized Solar Cells2010In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 110, no 11, p. 6595-6663Article, review/survey (Refereed)
  • 11.
    Hammar, Peter
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Córdova, Armando
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University.
    Himo, Fahmi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Density Functional Theory Study of the Stereoselectivity in Small Peptide-Catalyzed Intermolecular Aldol Reactions2008In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 19, p. 1617-1621Article in journal (Refereed)
    Abstract [en]

    The origins of the stereoselection of the dipeptide-catalyzed intermolecular aldol reaction are explored by means of hybrid density functional theory. Transition states were located for the (S)-ala-(S)-ala-catalyzed aldol reaction with cyclohexanone as the donor and benzaldehyde as the acceptor. The calculations reproduce the experimental trends very satisfactorily. It is demonstrated that the main Source of stereoselectivity is the interaction of the N-terminal amino acid side chain of the dipeptide with the cyclohexene ring.

  • 12. Hansson, Petra M.
    et al.
    Skedung, Lisa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Swerin, Agne
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Schoelkopf, Joachim
    Gane, Patrick A. C.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Robust Hydrophobic Surfaces Displaying Different Surface Roughness Scales While Maintaining the Same Wettability2011In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 27, no 13, p. 8153-8159Article in journal (Refereed)
    Abstract [en]

    A range of surfaces coated with spherical silica particles, covering the size range from nanometer to micrometer, have been produced using Langmuir-Blodgett (LB) deposition. The particles were characterized both in suspension and in the Langmuir trough to optimize the surface preparation procedure. By limiting the particle aggregation and surface layer failures during the preparation steps, well-defined monolayers with a close-packed structure have been obtained for all particle sizes. Thus, this procedure led to structured surfaces with a characteristic variation in the amplitude and spatial roughness parameters. In order to obtain robust surfaces, a sintering protocol and an AFM-based wear test to determine the stability of the deposited surface layer were employed. Hydrophobization of the LB films followed by water contact angle measurements showed, for all tested particle sizes, the same increase in contact angle compared to the contact angle of a flat hydrophobic surface. This indicates nearly hexagonal packing and gives evidence for nearly, complete surface wetting of the surface features.

  • 13.
    Hedberg, Jonas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Adsorption and Structure of Octadecanethiol on Zinc Surfaces As Probed by SumFrequency Generation Spectroscopy, Imaging, and Electrochemical Techniques2007In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 111, no 47, p. 17587-17596Article in journal (Refereed)
    Abstract [en]

    Octadecanethiol (ODT) adsorbed onto zinc has been studied with sum frequency generation (SFG), sum frequency generation imaging microscopy (SFG-IM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrical impedance spectroscopy (EIS) in order to investigate its corrosion protective ability and conformational ordering. SFG shows that ODT forms an ordered adsorbate on both reduced and oxidized zinc within short times after immersion in 1 mM ODT/ethanol solution. The corrosion protection, deduced by EIS, is also improved after immersion in the ODT solution. After longer immersion times, the corrosion protection decreases as well as the conformational order of the adsorbed ODT. Increasing the ODT concentration avoids this degradation with prolonged immersion time. The ODT is seen in the XPS spectra to adsorb to the reduced as well as the oxidized zinc by forming a Zn-S bond for both short and long immersion times. The SFG-IM completes the picture, showing a heterogeneous surface with areas corresponding to ordered ODT as well as disordered or uncovered regions. The density of adsorbed ODT after 24 h immersion time for both reduced and oxidized zinc was deduced from CV and was found to be approximately 6.7 x 10(-9) mol/cm(2).

  • 14.
    Hedberg, Jonas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Molecular in-situ observations of hydroxyl groups and ligand exchange during initial atmospheric corrosionManuscript (preprint) (Other academic)
  • 15.
    Hedberg, Jonas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Molecular structural information of the atmospheric corrosion of zinc studied by vibrational spectroscopy techniques: Part I. Experimental approachManuscript (preprint) (Other academic)
  • 16.
    Hedberg, Jonas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Molecular structural information of the atmospheric corrosion of zinc studied by vibrational spectroscopy techniques: Part II. Two and three dimensional growth of reaction products induced by formic and acetic acidManuscript (preprint) (Other academic)
  • 17.
    Hofström, Camilla
    et al.
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Altai, Mohamed
    Honarvar, H.
    Strand, J.
    Malmberg, J.
    Hosseinimehr, Seyed Jalal
    Orlova, Anna
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Tolmachev, Vladimir
    HAHAHA, HEHEHE,HIHIHI or HKHKHK: influence of position and composition of histidine containing tags on biodistribution of [99mTc(CO)3]+-labeled Affibody moleculesManuscript (preprint) (Other academic)
  • 18.
    Hofström, Camilla
    et al.
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Orlova, Anna
    Altai, Mohamed
    Wångsell, Fredrik
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Tolmachev, Vladimir
    Use of a HEHEHE Purification Tag Instead of a Hexahistidine Tag Improves Biodistribution of Affibody Molecules Site-Specifically Labeled with Tc-99m, In-111 and I-1252011In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 54, no 11, p. 3817-3826Article in journal (Refereed)
    Abstract [en]

    Affibody molecules are a class of small (similar to 7 kDa) robust scaffold proteins suitable for radionuclide molecular imaging in vivo. The attachment of a hexahistidine (His(6))-tag to the Affibody molecule allows facile purification by immobilized metal ion affinity chromatography (IMAC) but leads to high accumulation of radioactivity in the liver. Earlier, we have demonstrated that replacement of the His(6)- tag with the negatively charged histidine-glutamate-histidine-glutamate-histidine-glutamate (HEHEHE)-tag permits purification of Affibody molecules by IMAC, enables labeling with [Tc-99m(CO)(3)](+), and provides low hepatic accumulation of radioactivity. In this study, we compared the biodistribution of cysteine-containing Affibody molecules site-specifically labeled with In-111, Tc-99m, and I-125 at the C-terminus, having a His(6)-tag at the N- or C-terminus or a HEHEHE-tag at the N-terminus. We show that the use of a HEHEHE-tag provides appreciable reduction of hepatic radioactivity, especially for radiometal labels. We hope that this information can also be useful for development of other scaffold protein-based imaging agents.

  • 19.
    Hofström, Camilla
    et al.
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Stadler, C.
    Vermet, E.
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Step-wise down regulationof the epidermal growth factor receptor by affinity-based intracellular redirectionManuscript (preprint) (Other academic)
  • 20.
    Holmboe, Michael
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    The bentonite barrier: microstructural aspects on colloid filtration and radiation effects on bentonite colloid stability2009Licentiate thesis, comprehensive summary (Other academic)
  • 21.
    Ibrahem, Ismail
    et al.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University.
    Rios, Ramon
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University.
    Vesely, Jan
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University.
    Hammar, Peter
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Eriksson, Lars
    Department of Structural Chemistry, Arrhenius Laboratory, Stockholm University.
    Himo, Fahmi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Córdova, Armando
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University.
    Enantioselective Organocatalytic Hydrophosphination of α,β-Unsaturated Aldehydes2007In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 46, no 24, p. 4507-4510Article in journal (Refereed)
    Abstract [en]

    Keeping it simple: Optically active phosphine derivatives can be obtained in high yields and in up to 99% ee by using simple chiral amines to catalyze the hydrophosphination of α,β-unsaturated aldehydes (see scheme, green sphere = chiral group). The synthetic utility of this highly chemo- and enantioselective transformation was exemplified by the one-pot asymmetric synthesis of β-phosphine oxide acids.

  • 22. Khalil, W. K. B.
    et al.
    Girgis, E.
    Emam, A. N.
    Mohamed, M. B.
    Rao, K. Venkat
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Genotoxicity Evaluation of Nanomaterials: DNA Damage, Micronuclei, and 8-Hydroxy-2-deoxyguanosine Induced by Magnetic Doped CdSe Quantum Dots in Male Mice2011In: Chemical Research in Toxicology, ISSN 0893-228X, E-ISSN 1520-5010, Vol. 24, no 5, p. 640-650Article in journal (Refereed)
    Abstract [en]

    Quantum dots (QDs) are a novel class of inorganic fluorophores which are gaining widespread recognition as a result of their exceptional photophysical properties and their applications as a biomarker and in molecular biomedical imaging. The aim of this study was to evaluate the in vivo genotoxicity in mice exposed to CdSe quantum dots of average size 5.0 +/- 0.2 nm and CdSe doped with 1% cobalt ions of similar size. The quantum dots are surface modified using mercaptoacetic acid (MAA) in order to be biocompatible and water-soluble. The MAA-QDs were given to the mice orally at doses of 500, 1000, and 2000 mg/kg by weight of MAA-QDs. Bone marrow and liver samples were collected after two and seven days of treatment. The results indicated that after two days of treatment, the high dose of doped MAA-QDs was significantly able to induce DNA damage, formation of micronuclei (MNs), and generation of DNA adduct (8-hydroxy-2-deoxyguanosine, 8-OHdG). However, increasing DNA damage and the frequency of MNs formation as well as the generation of DNA adducts were observed with both the undoped MAA-QDs (2000 mg/kg) and doped MAA-QDs (1000 and 2000 mg/kg) after seven days of treatment. The results of our study indicate that exposure to high doses of pure MAA-QDs or MAA-QDs doped with cobalt has the potential to cause indirect in vivo genetic damage, which may be attributed to free radical-induced oxidative stress in mice.

  • 23.
    Li, Zhenyu
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Zhang, Wenhua
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Luo, Yi
    KTH, School of Biotechnology (BIO).
    Hou, Jian Guo
    How Graphene is Cut upon Oxidation?2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 18, p. 6320-6321Article in journal (Refereed)
    Abstract [en]

    Our first principles calculations reveal that an oxidative cut of graphene is realized by forming epoxy and then carbonyl pairs. Direct formation of a carbonyl pair to tear graphene up from an edge position is not favorable in energy. This atomic picture is valuable for developing effective means of graphene manipulation. The proposed epoxy pairs may be related to some long puzzling experimental observations on graphene oxide.

  • 24.
    Liao, Rong-Zhen
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Mechanistic insights into dinuclear zinc enzymes from density functional theory studies2009Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, quantum chemical methods have been used to shed light on the reaction mechanisms of several dinuclear zinc enzymes. The enzymes studied are involved in the hydrolysis of phosphates, amides, and carboxylic esters, namely RNase Z, Dihydroorotase (DHO), and N-acyl homoserine lactone hydrolase (AHL lactonase). The density functional method B3LYP, together with quite large active site models, was used to investigate these enzymatic reactions. Several plausible proposed mechanisms, involving protonation states of important active site residues (DHO), substrate orientations (AHL lactonase), have been considered. The calculated energetics can be used to assess the feasibility of the suggested reaction mechanisms. Based on the calculations and also on other related dinuclear zinc enzymes studied previously, some general mechanistic features have been uncovered.

    For all three enzymes, the nucleophilicity of the bridging hydroxide is shown to be sufficient to perform the nucleophilic attack on the substrates. During the attack, the negative charge is transferred from the bridging hydroxide to the substrate oxygen (P=O or C=O). For phosphate hydrolysis, an in line attack have been suggested for RNase Z. In addition, the two zinc ions in RNase Z are directly involved in stabilizing the negative charge in the penta-coordinated transition states. For carbonyl substrates, only one zinc ion participates in the oxygen anion stabilization in the transition states and the tetrahedral intermediates. Furthermore, the enzymes always use the zinc ion with less negatively-charged ligands to play such role.

    All the substrates investigated have poor leaving groups. Therefore, either the zinc ions or some active site residues help the cleavage of the scissile bond. For RNase Z, a Glu-His diad was suggested to protonate the leaving group. For DHO, an Asp residue was shown to transfer a proton from the bridging hydroxide to the leaving group nitrogen. For AHL lactonase, a zinc ion was also observed to stabilize the leaving oxygen anion.

  • 25.
    Liu, Rong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Enzymes as catalysts in synthesis of enantiomerically pure building blocks: secondary alcohols bearing two vicinal stereocenters2005Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Enzymes as tools in organic synthesis have provided enormous advantages. This thesis deals with the applications of enzymes in the kinetic resolutions of racemic compounds. The stereochemistry of chiral compounds and the kinetics of α/β hydrolase lipases are presented. From a practical point of view, the handling of a large number of parameters that influences the kinetic resolutions, especially enantioselectivity (E-value) are systematically described. A variety of approaches employed for raising the yields to over 50% are additionally discussed.

    Methods for the preparation of synthetically useful chiral building blocks were developed in this thesis. Thus, resolution of secondary alcohols bearing two vicinal stereocentres are studied. These building blocks can serve as starting materials for the synthesis of various enantiomerically pure compounds for agrochemistry, pharmaceuticals, chemical industry, and particularly for the total synthesis of pheromones.

    Racemic 3-substitued 2-hydroxybutane derivatives were produced in fairly high diastereomeric purities by a variety of chemical approaches, such as epimerization, metal-catalysed asymmetric addition etc. Kinetic resolution of these racemates was achieved by enzyme-catalysed reactions. Two lipases, Candida antarctica lipase B and Pseudomonas cepacia lipase were found to be useful in acylations as well as hydrolyses. In the biotransformations studied, the presence and nature of the second vicinal stereocentre in the chiral secondary alcohols investigated seemed to be important, e.g. in terms of the efficiencies of sequential kinetic resolutions, and altering the selectivities as well.

  • 26.
    Liu, Rong
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Högberg, Hans-Erik
    Mittuniversitetet.
    Preparation of the four stereoisomers of 3-bromo-2-butanol or their acetates via lipase-catalysed resolutions of the racemates derived from dl- or meso-2,3-butanediol.2005In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 16, p. 2607-2611Article in journal (Refereed)
    Abstract [en]

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

  • 27.
    Lönnberg, Hanna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Ring-opening polymerization from cellulose for biocomposite applications2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There is an emerging interest in the development of sustainable materials with high performance. Cellulose is promising in this regard as it is a renewablere source with high specific properties, which can be utilized as strong reinforcements in novel biocomposites. However, to fully exploit the potential ofcellulose, its inherent hydrophilic character has to be modified in order toimprove the compatibility and interfacial adhesion with the more hydrophobicpolymer matrices commonly used in composites.In this study, the grafting of poly(ε-caprolactone) (PCL) and poly(L-lactide)(PLLA) from cellulose surfaces, via ring-opening polymerization (ROP) of ε-caprolactone and L-lactide, was investigated. Both macroscopic and nano-sizedcellulose were explored, such as filter paper, microfibrillated cellulose (MFC),MFC-films, and regenerated cellulose spheres. It was found that thehydrophobicity of the cellulose surfaces increased with longer graft lengths, andthat polymer grafting rendered a smoother surface morphology.To improve the grafting efficiency in the ROP from filter paper, both covalent(bis(methylol)propionic acid, bis-MPA) and physical pretreatment (xyloglucanbisMPA)were explored. The highest grafting efficiency was obtained with ROPfrom the bis-MPA modified filter papers, which significantly increased amountof polymer on the surface, i.e. the thickness of the grafted polymer layer.MFC was grafted with PCL to different molecular weights. The dispersability innon-polar solvent was obviously improved for the PCL grafted MFC, incomparison to neat MFC, and the stability of the MFC suspensions was better maintained with longer grafts. PCL based biocomposites were prepared from neat MFC and PCL grafted MFCwith different graft lengths. The polymer grafting improved the mechanical properties of the composites, and the best reinforcing effect was obtained when PCL grafted MFC with the longest grafts were used as reinforcement.A bilayer laminate consisting of PCL and MFC-films grafted with different PCL graft lengths displayed a gradual increase in the interfacial adhesion with increasing graft length.The effect of grafting on the adhesion was also investigated via colloidal probeatomic force microscopy at different temperatures and time in contact. A significant improvement in the adhesion was observed after polymer grafting.

  • 28. Maddalo, Gianluca
    et al.
    Shariatgorji, Mohammadreza
    Adams, Christopher M.
    Fung, Eva
    Nilsson, Ulrika
    Zubarev, Roman A.
    Sedzik, Jan
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Ilag, Leopold L.
    Porcine P2 myelin protein primary structure and bound fatty acids determined by mass spectrometry (vol 397, pg 1903, 2010)2010In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 398, no 7-8, p. 3225-3226Article in journal (Refereed)
  • 29.
    Nilsson, Fritjof
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Small-Molecule Diffusion in Semicrystalline Polymers as Revealed by Experimental and Simulation Studies2010In: POLYCHAR-18 WORLD FORUM ON ADVANCED MATERIALS / [ed] Mormann, W., Weinheim: WILEY-V C H VERLAG , 2010, Vol. 298, p. 108-115Conference paper (Refereed)
    Abstract [en]

    Diffusion of n-hexane in poly(ethylene-co-1-hexene)s with 15-75 wt.% crystallinity was studied by desorption experiments analyzing data using the Fickian equations with a concentration dependent diffusivity. The effect of the impenetrable crystalline phase on the penetrant diffusivity (D) is described by D = D-a/(tau beta), where D-a is the diffusivity of the amorphous polymer, tau is the geometrical impedance factor and beta is a factor describing the constraining effect of the crystals on the non-crystalline phase. For a polymer with 75 wt.% crystallinity, tau beta varied markedly with penetrant concentration (V-1a) in the penetrable phase: 1000 (V-1a = 0) and 10 (V-1a = 0.15). This penetrant-uptake had no effect on the gross crystal morphology, i.e. beta must be strongly dependent on V-1a. Samples saturated in n-hexane exhibited a penetrant-induced loosening of the interfacial structure, as revealed by an increase in crystal density that require an increased mobility in the interfacial component and by a decrease in the intensity of the asymmetric X-ray scattering associated with the interfacial component. The geometrical impedance factor has been modelled by mimicking spherulite growth and tau was obtained as the ratio of the diffusivities of the fully amorphous and semicrystalline systems. The maximum tau obtained from these simulations is ca. ten, which suggests that beta in the systems with V-1a = 0.15 takes values close to unity. The simulations showed that the geometrical impedance factor is insensitive to the ratio of the crystal width and the crystal thickness. A free path length scaling parameter characteristic of the amorphous phase correlated with tau.

  • 30.
    Rodriguez, Raul
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Upflow anaerobic sludge blanket reactor: modelling2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Anaerobic treatment is widely used around the world as a biological stage in both domestic and industrial wastewater-treatment plants. The two principal advantages of anaerobic over aerobic treatment are the production of biogas, which can be used as fuel, and the lower rate of biomass production, which results in lower maintenance costs for the plant. The upflow anaerobic sludge blanket (UASB) reactor is an attractive alternative for regions in hot climates since it works better under mesophilic conditions and it does not need any supporting structure for the development of microorganisms, which grow in the form of granules.

    In this thesis, a model describing the UASB reactor behaviour with respect to substrate degradation, microorganism growth and granule formation was developed. The model is transient and is based on mass balances for the substrate and microorganisms in the reactor. For the substrate, the processes included in the model are dispersion, advection and degradation of the organic matter in the substrate. The reaction rate for the microorganisms includes the growth and decay of the microorganisms. The decay takes into account the microorganism dying and the fraction of biomass that may be dragged into the effluent. The microorganism development is described by a Monod type equation including the death constant; the use of the Contois equation for describing the microorganism growth was also addressed.

     An equation considering the substrate degradation in the granule was required, since in the UASB reactor the microorganisms form granules. For this, a stationary mass balance within the granule was carried out and an expression for the reaction kinetics was then developed. The model for the granule takes into account the mass transport through the stagnant film around the granule, the intraparticle diffusion, and the specific degradation rate. The model was solved using commercial software (COMSOL Multiphysics). The model was validated using results reported in the literature from experiments carried out at pilot scale.

    A simplified model was also developed considering the case in which the microorganisms are dispersed in the reactor and granules are not formed. The UASB reactor is then described as formed by many well-stirred reactors in series. The model was tested using experimental results from the literature and the sensitivity of the processes to model parameters was also addressed. The models describe satisfactorily the degradation of substrate along the height in the reactor; the major part of the substrate is degraded at the bottom of the reactor due to the high density of biomass present in that region. This type of model is a useful tool to optimize the operation of the reactor and to predict its performance.

     

  • 31.
    Rodriguez, Raul
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Simulation of a UASB reactor2011Article in journal (Other academic)
    Abstract [en]

    A model has been developed to describe the behaviour of a UASB reactor with respect to substrate degradation, microorganism growth and granule size. The model is transient and includes advection, dispersion, and reaction terms. It also considers microorganism decay and the fraction of the biomass that can be dragged by the effluent. A mass balance was established in order to obtain an expression for the rate of the reaction occurring in the granule. It takes into account the resistance due to the mass transport through the stagnant film around the granule, the intra-particle diffusion, and the degradation rate within the granule.

     The model was solved using COMSOL Multiphysics software and data from the literature were used to study the performance of the model. The agreement between the model and the experimental results was satisfactory. The majority of the substrate is degraded at the bottom of the reactor due to the high density of granules present in that region. This kind of simulation may be a very helpful tool in the development and improvement of UASB reactors by predicting the reactor performance under different operating conditions.

  • 32.
    Skedung, Lisa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Tactile Perception - Role of Physical Properties2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aim of this thesis is to interconnect human tactile perception with various physical properties of materials. Tactile perception necessitates contact and relative motion between the skin and the surfaces of interest. This implies that properties such as friction and surface roughness ought to be important physical properties for tactile sensing. In this work, a method to measure friction between human fingers and surfaces is presented. This method is believed to best represent friction in tactile perception.

    This study is focused on the tactile perception of printing papers. However, the methodology of finger friction measurements, as well as the methodology to link physical properties with human perception data, can be applied to almost whichever material or surfaces.

     

    This thesis is based on three articles.

     

    In Article I, one participant performed finger friction measurements, using a piezoelectric force sensor, on 21 printing papers of different paper grades and grammage (weight of the papers). Friction coefficients were calculated as the ratio of the frictional force and the normal force, shown to have a linear relationship. The values were recorded while stroking the index finger over the surface. The results show that measurements with the device can be used to discriminate a set of similar surfaces in terms of finger friction. When comparing the friction coefficients, the papers group according to paper surface treatment and an emerging trend is that the rougher (uncoated) papers have a lower friction coefficient than the smoother (coated) papers. In the latter case, this is interpreted in terms of a larger contact between the finger and paper surface.

     

    In addition, a decrease in friction coefficient is noted for all papers on repeated stroking, where the coated papers display a larger decrease. XPS (X-ray Photoelectron Spectroscopy) reveals that skin lipids are transferred from the finger to the paper surface, acting as a lubricant and hence decrease friction. Nevertheless, there is evidence that mechanical changes of the surface cannot be completely ruled out.

     

    The reproducibility of the finger friction measurements is elaborated in Article II, by using many participants on a selection of eight printing papers out of the 21. The trends in friction are the same; once again, the coated papers display the highest friction. There are notably large variations in the exact value of the friction coefficient, which are tentatively attributed to different skin hydration and stroking modes.

     

    These same participants also took part in a tactile study of perceived paper coarseness (“strävhet” in Swedish). The results reveal that the participants can distinguish a set of printing papers in terms of perceived coarseness. Not unexpectedly, surface roughness appears to be an important property related to perceived coarseness, where group data display that perceived coarseness increases with increasing surface roughness. Interestingly, friction also appears to be a discriminatory property for some subjects. A few participants showed opposite trends, which is evidence for that what is considered coarse is subjective and that different participants “weigh” the importance of the properties differently. This is a good example of a challenge when measuring one-dimensional perceptions in psychophysics.

     

    In Article III, a multidimensional approach was used to explore the tactile perception of printing papers. To do this, the participants scaled similarity among all possible pairs of the papers, and this similarity data are best presented by a three-dimensional space solution. This means that there are three underlying dimensions or properties that the participants use to discriminate the surface feel. Also, there is a distinct perceptual difference between the rougher (uncoated) and smoother (coated) papers. The surface roughness appears to be the dominant physical property when discriminating between a real rough paper and a smooth paper, whereas friction, thermal conductivity and grammage are more important when discriminating among the smooth coated papers.

  • 33.
    Skedung, Lisa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Danerlöv, Katrin
    Institute for Surface Chemistry (YTK), Stockholm, Sweden.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Johannesson, Carl Michael
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Aikala, Maiju
    Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), Espoo, Finland.
    Kettle, John
    Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), Espoo, Finland.
    Arvidsson, Martin
    Department of Psychology, Stockholm University, Sweden.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Reproducibility of finger friction, surface roughness and perception of printing papersArticle in journal (Other academic)
  • 34.
    Sörensen, Malin Helena
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Mesostructured particulate silica materials with tunable pore size: Synthesis, characterization and applications2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Colloidal assemblies of surfactants and polymers in aqueous solutions have been used by human mankind for hundreds of years and they are of great importance in many of our technological processes, such as fabrication of soap and papermaking. Less than two decades ago the idea of using colloidal assemblies as templates of inorganic materials was borne. A new population of materials, referred to as surfactant templated materials, took form. These materials showed extraordinary properties such as monodisperse pore size distribution, large surface areas and pore volumes.

     

    The main focus of this thesis has been on synthesis and functionalisation of spherical mesostructured silica particulate materials. In the first part of the work, mesostructured materials with expanded pores have been produced using a well established aerosol-based method as well as the newly developed emulsion and solvent evaporation (ESE) method. Increase in pore size was realized through using Pluronic block copolymer F127 together with a swelling agent poly(propylene glycol) as template. The influence of the swelling agent on pore size expansion was shown to have a roughly linear relationship. Furthermore, the impact of synthesis parameters on internal and exterior morphology has been investigated. Accessibility of the internal pore space, as well as the external surface roughness were shown to be highly dependent on synthesis temperature. Additionally, a very interesting well ordered 3D closed packed (P63/mmc) material was produced using the ionic surfactant C16TAB as template in the ESE method.

     

    In the second part of the thesis work, mesoporous spheres with large pore size, having either hydrophilic or hydrophobic surface properties, were used as carriers of an enzyme, lipase. The enzymatic activity of lipase was increased onto the hydrophobic surface, compared to lipase immobilized into the hydrophilic support as well as for lipase free in solution. This effect was probably due to a combination of enhanced hydrophobic interactions preventing denaturation of the enzyme and interfacial activation of the enzyme.  This study generated an inorganic carrier material that is a promising candidate for biocatalysis applications. Additionally, mesoporous spheres were used as carriers of a model drug, Ibuprofen, to study the effect of polyelectrolyte multilayers on release properties. However, these layers were shown impermeable independent on pH and the substance was only released from uncoated particles.

  • 35.
    Tian, Haining
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yu, Ze
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Hagfeldt, Anders
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Organic Redox Couples and Organic Counter Electrode for Efficient Organic Dye-Sensitized Solar Cells2011In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, no 24, p. 9413-9422Article in journal (Refereed)
    Abstract [en]

    A series of organic thiolate/disulfide redox couples have been synthesized and have been studied systematically in dye-sensitized solar cells (DSCs) on the basis of an organic dye (TH305). Photophysical, photoelectrochemical, and photovoltaic measurements were performed in order to get insights into the effects of different redox couples on the performance of DSCs. The polymeric, organic poly(3,4-ethylenedioxythiophene) (PEDOT) material has also been introduced as counter electrode in this kind of noniodine-containing DSCs showing a promising conversion efficiency of 6.0% under AM 1.5G, 100 mW.cm(-2) light illumination. Detailed studies using electrochemical impedance spectroscopy and linear-sweep voltammetry reveal that the reduction of disulfide species is more efficient on the PEDOT counter electrode surface than on the commonly used platinized conducting glass electrode. Both pure and solvated ionic-liquid electrolytes based on a thiolate anion have been studied in the DSCs. The pure and solvated ionic-liquid-based electrolytes containing an organic redox couple render efficiencies of 3.4% and 1.2% under 10 mW.cm(-2) light illumination, respectively.

  • 36.
    Trey, Stacy M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Netrval, Julia
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Johansson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Electron-Beam-Initiated Polymerization of Poly(ethylene glycol)-Based Wood Impregnants2010In: ACS APPL MATER INTERFACES, ISSN 1944-8244, Vol. 2, no 11, p. 3352-3362Article in journal (Refereed)
    Abstract [en]

    The current study demonstrates that methacrylate and acrylate poly(ethylene glycol) (PEG) functional oligomers can be effectively impregnated into wood blocks and cured efficiently to high conversions without catalyst by e-beam radiation, allowing for less susceptibility to leaching, and favorable properties including higher Brinell hardness values. PEG based monomers were chosen because there is a long history of this water-soluble monomer being able to penetrate the cell wall, thus bulking it and decreasing the uptake of water which further protects the wood from fungal attack. Diacrylate dimethacrylate and dihydroxyl functional PEG of M-v, 550-575 of concentration 0-30, 60 and 100 wt % in water, were vacuum pressure impregnated into Scots Pine blocks of 15 x 25 x 50 mm in an effort to bulk the cell wall. The samples were then irradiated and compared with nonirradiated samples it was shown by IR, DSC that the acrylate polymers were fully cured to much higher conversions than can be reached with conventional methods Leaching studies indicated a much lower amount of oligomer loss from the cured to much higher conversions than can be reached with conventional methods functional PEG indication a high degree of fastening of the polymer in the wood. The Brinell hardness indicated a significant increase in hardness to hardwood levels in the modified samples compared to the samples of hydroxyl functional PEG and uncured vinyl PEC samples, which actually became softer than the untreated Scots Pine. By monitoring the dimensions of the sample it was found by weight percent gain calculations WPC %) that water helps to swell the wood structure and allow better access of the oligomers into the cell wall as this was not observed for methyl methacrylate which is well-cocumented to remain in the lumen. However dimensional stability of the viny ploymer modified blocks when placed in water was not observed to the same extent as PEG.

  • 37.
    Ullsten, Henrik
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Processing and Development of Wheat Gluten Plastics2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

     Renewable packaging materials are of interest for a more sustainable environment. Wheat gluten is one of the most interesting candidates to replace petroleum-based oxygen-barrier polymers for packaging applications. The high amount of hydrogen bonds makes wheat gluten interesting as oxygen barrier films with sufficient elastomeric mechanical properties. Wheat gluten based materials are homogeneous, mechanically strong and relatively water insoluble compared with other biological materials. Several studies of wheat gluten films have been performed on solution cast films and a few studies have been executed on compression molding. Extrusion, without solvents, is the most common and fastest processing method for the production of packaging films. In order to develop wheat gluten films to commercially competitive material it is crucial to make the material extrudable.The temperature window for extrusion of glycerol-plasticized wheat gluten was increased by the use of salicylic acid, a known scorch retarder and radical scavenger. Small effects of shear-induced heating during extrusion at the higher temperatures suggested that the acid acted as a lubricant and viscosity reducer. The latter was suggested to originate primarily from the salicylic-acid-induced reduction in the degree of protein aggregation/crosslinking, as indicated by size-exclusion high-performance liquid chromatography and chemiluminescence. Electron paramagnetic resonance spectroscopy on extruded films indicated that the beneficial effect of salicylic acid was due to its radical scavenging effect. The complex shear modulus increased more slowly with increasing salicylic acid content above 110-120°C, indicating that the aggregation/crosslinking rate was slower with salicylic acid, i.e. that it did have a scorch-retarding effect, besides yielding a lower final degree/complexity of aggregation.Sodium hydroxide was used as an additive to be able to extrude gluten at alkaline conditions. The oxygen barrier, at dry conditions, was improved significantly with the addition of sodium hydroxide. Oxygen transmission rate measurements, tensile tests, protein solubility, glycerol migration, infrared spectroscopy and electrophoresis were used to assess the properties of the extrudate. It was observed that the extrudate with 3 wt.% sodium hydroxide had the most suitable combination of properties, low oxygen permeability, large strain at break and relatively small aging-induced changes in mechanical properties, the reason probably due to high protein aggregation and low plasticizer migration.As an alternative method to get alkaline conditions ammonium hydroxide was added. It resulted in a three times stronger film compared to the pure gluten glycerol material and had an oxygen barrier that can favorably be compared with these of oriented polyethylene terephtalat or Nylon 66.Several plasticizers were examined in a screening test where the extrusion properties were predicted in a plasticorder. The temperature and melt viscosity were recorded during the kneading. The most promising plasticizers were chosen to further studies with tensile tests. Glycerol was shown to be the most efficient plasticizer for thermoformed gluten films.In order to use wheat gluten as a packaging material, it is important to be able to seal it. Wheat gluten films, molded at 100–130°C, were sealed by impulse sealing at 120– 175°C. The lap-shear and peel strength of the sealed films were evaluated. The lapshear strength was greater than or similar to that of polyethylene film, although the peel strength was poorer.

  • 38. Wang, Z.
    et al.
    Fu, Y.
    Kang, Zhengzhong
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Liu, X.
    Chen, N.
    Wang, Q.
    Tu, Yaoquan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Wang, L.
    Song, S.
    Ling, D.
    Song, H.
    Kong, X.
    Fan, C.
    Organelle-Specific Triggered Release of Immunostimulatory Oligonucleotides from Intrinsically Coordinated DNA-Metal-Organic Frameworks with Soluble Exoskeleton2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 44, p. 15784-15791Article in journal (Refereed)
    Abstract [en]

    DNA has proven of high utility to modulate the surface functionality of metal-organic frameworks (MOFs) for various biomedical applications. Nevertheless, current methods for preparing DNA-MOF nanoparticles rely on either inefficient covalent conjugation or specific modification of oligonucleotides. In this work, we report that unmodified oligonucleotides can be loaded on MOFs with high density (∼2500 strands/particle) via intrinsic, multivalent coordination between DNA backbone phosphate and unsaturated zirconium sites on MOFs. More significantly, surface-bound DNA can be efficiently released in either bulk solution or specific organelles in live cells when free phosphate ions are present. As a proof-of-concept for using this novel type of DNA-MOFs in immunotherapy, we prepared a construct of immunostimulatory DNA-MOFs (isMOFs) by intrinsically coordinating cytosine-phosphate-guanosine (CpG) oligonucleotides on biocompatible zirconium MOF nanoparticles, which was further armed by a protection shell of calcium phosphate (CaP) exoskeleton. We demonstrated that isMOFs exhibited high cellular uptake, organelle specificity, and spatiotemporal control of Toll-like receptors (TLR)-triggered immune responses. When isMOF reached endolysosomes via microtubule-mediated trafficking, the CaP exoskeleton dissolved in the acidic environment and in situ generated free phosphate ions. As a result, CpG was released from isMOFs and stimulated potent immunostimulation in living macrophage cells. Compared with naked CpG-MOF, isMOFs exhibited 83-fold up-regulation in stimulated secretion of cytokines. We thus expect this isMOF design with soluble CaP exoskeleton and an embedded sequential "protect-release" program provides a highly generic approach for intracellular delivery of therapeutic nucleic acids.

  • 39.
    Westerlund, Kristina
    et al.
    KTH, School of Biotechnology (BIO), Protein Technology.
    Honarvar, H.
    Tolmachev, V.
    Eriksson Karlström, Amelie
    KTH, School of Biotechnology (BIO), Protein Technology.
    Design, Preparation, and Characterization of PNA-Based Hybridization Probes for Affibody-Molecule-Mediated Pretargeting2015In: Bioconjugate chemistry, ISSN 1043-1802, E-ISSN 1520-4812, Vol. 26, no 8, p. 1724-1736Article in journal (Refereed)
    Abstract [en]

    In radioimmunotherapy, the contrast between tumor and normal tissue can be improved by using a pretargeting strategy with a primary targeting agent, which is conjugated to a recognition tag, and a secondary radiolabeled molecule binding specifically to the recognition tag. The secondary molecule is injected after the targeting agent has accumulated in the tumor and is designed to have a favorable biodistribution profile, with fast clearance from blood and low uptake in normal tissues. In this study, we have designed and evaluated two complementary peptide nucleic acid (PNA)-based probes for specific and high-affinity association in vivo. An anti-HER2 Affibody-PNA chimera, Z<inf>HER2:342</inf>-SR-HP1, was produced by a semisynthetic approach using sortase A catalyzed ligation of a recombinantly produced Affibody molecule to a PNA-based HP1-probe assembled using solid-phase chemistry. A complementary HP2 probe carrying a DOTA chelator and a tyrosine for dual radiolabeling was prepared by solid-phase synthesis. Circular dichroism (CD) spectroscopy and UV thermal melts showed that the probes can hybridize to form a structured duplex with a very high melting temperature (T<inf>m</inf>), both in HP1:HP2 and in Z<inf>HER2:342</inf>-SR-HP1:HP2 (T<inf>m</inf> = 86-88 °C), and the high binding affinity between Z<inf>HER2:342</inf>-SR-HP1 and HP2 was confirmed in a surface plasmon resonance (SPR)-based binding study. Following a moderately fast association (1.7 × 105 M-1 s-1), the dissociation of the probes was extremely slow and <5% dissociation was observed after 17 h. The equilibrium dissociation constant (K<inf>D</inf>) for Z<inf>HER2:342</inf>-SR-HP1:HP2 binding to HER2 was estimated by SPR to be 212 pM, suggesting that the conjugation to PNA does not impair Affibody binding to HER2. The biodistribution profiles of 111In- and 125I-labeled HP2 were measured in NMRI mice, showing very fast blood clearance rates and low accumulation of radioactivity in kidneys and other organs. The measured radioactivity in blood was 0.63 ± 0.15 and 0.41 ± 0.15%ID/g for 125I- and 111In-HP2, respectively, at 1 h p.i., and at 4 h p.i., the kidney accumulation of radioactivity was 0.17 ± 0.04%ID/g for 125I-HP2 and 3.83 ± 0.39%ID/g for 111In-HP2. Taken together, the results suggest that a PNA-based system has suitable biophysical and in vivo properties and is a promising approach for pretargeting of Affibody molecules.

  • 40.
    Zazzi, Åsa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Chlorite: Geochemical properties, Dissolution kinetcis and Ni(II) sorption2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In Sweden, among other countries, a deep multi-barrier geological repository, KBS-3, is planned for the burial of nuclear waste. One of the barriers is identified as the grantic bedrock itself and in this environment chlorite is present at surfaces in fracture zones.

    This thesis is focused on characterisation of chlorite samples and studies of their dissolution and sorption behaviour, in order to verify chlorites capacity to retard possible radionuclide migration in the case of leaking canisters.

    Chlorite dissolution of has been studied in the pH interval 2-12, and as expected the dissolution is highest at acidic pH and at most alkaline pH, whereas dissolution is lowest at near neutral pH values. Chemical and physical properties of chlorites clearly influence the dissolution rates, and at steady-state dissolution rates in the interval 10-12 ‑ 10-13 mol g-1 s-1 was observed.

    Sorption studies were performed since Ni(II) is one of the important activation products in spent nuclear fuel and sorption data on minerals like chlorite are lacking. Ni(II) sorption onto chlorite was studied using batch technique as a function of; pH, concentration of Ni(II), ionic strength and solid concentrations. As expected, the sorption of Ni(II) onto chlorite was pH dependent, but not ionic strength dependent, with a sorption maximum at pH ~ 8, and with a Kd of ~ 103 cm3/g. This confirms that the Ni(II) sorption onto chlorite is primarily acting through surface complexation. The acid-base properties were determined by titrations and described by a non-electrostatical surface complexation model in FITEQL. Further, the sorption results were fit with a 2-pK NEM model and three surface complexes, Chl_OHNi2+, Chl_OHNi(OH)+ and Chl_OHNi(OH)2, gave the best fit using FITEQL.

  • 41.
    Zelenin, Sergey
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Käller, M.
    Nazarov, A.
    Brismar, H.
    Russom, Aman
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    High density custom microarrays formed by microcompartment amplification on glass surface2014In: 18th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2014, Chemical and Biological Microsystems Society , 2014, p. 1027-1029Conference paper (Refereed)
    Abstract [en]

    Compartmentalization of a single DNA molecule is necessary for digital amplification. In the present study we have developed a microscale isothermal amplification using exponential rolling circle amplification (RCA). RCA was performed in PDMS microcompartments on a microarray glass, with a volume of less than 1 pL. Resulting amplicons were attached to the glass surface and formed a custom array with the density of spots above 2,5 × 105 per cm2. Our technology can be applied for digital amplification of DNA or RNA from a variety of complex biological samples in a microchip format.

  • 42.
    Åkerstedt, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Tailored Reaction Media for the Synthesis of Subvalent Cluster Compounds2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Different synthetic approaches and modifications to reaction media have been applied in order to find new routes to the synthesis of main-group clusters and transition metal compounds. The focus has been on the Group 15 element bismuth and the transition metal palladium. The reactions performed have mainly been Lewis acid-base reactions and the characterization tools used X-ray diffraction and Raman spectroscopy.

    The Bi5[GaCl4]3 salt, previously known form synthesis using other reaction routes, has been isolated from GaCl3-dichloromethane media. The salt containing the subvalent naked bismuth polycation Bi53+ was isolated from the reduction of bismuth(III) chloride. Quantum chemical calculations on the interaction energies of the isolated bismuth cluster show the dichloromethane-cluster interaction energy to be higher than that between benzene and the cluster.

    Ionic liquids have, in addition to dichloromethane, been shown to work as alternative reaction media for room-temperature synthesis of the Bi5[GaCl4]3 salt. Three different classes of ionic liquids have been used; phosphonium-, imidazolium- and pyrrolidinium-based salts. The ionic liquids used have been treated with Lewis acids in order to promote cluster formation.

    In this work three new palladium sandwich compounds have also been isolated, using GaCl3-arene reaction media; [Pd2(Ga2Cl7)(C7H8)2], [Pd2(GaCl4)(C9H12)2]∙C9H12 and [Pd2(Ga2Cl7)(C6H5Cl)2]. Quantum chemical calculations on these palladium sandwiches show the chlorobenzene sandwiching ligands unexpectedly interacting more strongly with the dipalladium unit than the methyl substituted arenes.

  • 43.
    Åkerstedt, Josefin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Gorlov, Mikhail
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Room-Temperature Synthesis of the Bi-5[GaCl4](3) Salt From Three Different Classes of Ionic Liquids2013In: Journal of cluster science, ISSN 1040-7278, E-ISSN 1572-8862, Vol. 24, no 1, p. 157-164Article in journal (Refereed)
    Abstract [en]

    Following the development in the synthesis of subvalent cluster compounds, we report on the use of three different classes of room-temperature ionic liquids for the synthesis of the pentabismuth-tris(tetragallate) salt, Bi-5[GaCl4](3), characterized by X-ray diffraction. The Bi-5[GaCl4](3) salt was prepared by reduction of BiCl3 using gallium metal in ionic liquid reaction media containing a strong Lewis acid, GaCl3. The ionic liquids; trihexyltetradecyl phosphonium chloride [Th-Td-P+]Cl-, 1-dodecyl-3-methylimidazolium chloride [Dod-Me-Im(+)]Cl- and N-butyl-N-methylpyrrolidinium chloride [Bu-Me-Pyrr(+)]Cl- from three of the main classes of ionic liquids were used in synthesis. Reactions using ionic liquids composed of the trihexyltetradecyl phosphonium cation [Th-Td-P+] and the anions; tetrafluoroborate [BF4 (-)], bis(trifluoro-methyl sulfonyl) imide [(Tf)(2)N-] and hexafluorophosphate [PF6 (-)] were also investigated.

  • 44.
    Åkerstedt, Josefin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Gorlov, Mikhail
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Synthesis of Bi5[GaCl4]3 from room-temperature ionic liquid reaction mediaManuscript (preprint) (Other academic)
  • 45.
    Åkerstedt, Josefin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Rosdahl, Jan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Persson, Per
    Umeå University.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Arsenic Clusters in Solution: An Experimental and A Priori Theoretical EXAFS StudyManuscript (preprint) (Other academic)
  • 46.
    Åkerstedt, Josefin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ruck, M.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Long, J. R.
    Tungsten Chloride W3Cl10(CH3CN)3 fromRoom-temperature Synthesis in Ionic liquid using an Organic Co-solventManuscript (preprint) (Other academic)
  • 47.
    Örnberg, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Electrochemical study of tantalum as substrate for pacemaker electrodesIn: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111Article in journal (Other academic)
1 - 47 of 47
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf