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  • 251.
    Lousada, Claudio Miguel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Soroka, Inna L.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Yagodzinskyy, Y.
    Tarakina, N. V.
    Todoshchenko, O.
    Hänninen, H.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Gamma radiation induces hydrogen absorption by copper in water2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 24234Article in journal (Refereed)
    Abstract [en]

    One of the most intricate issues of nuclear power is the long-term safety of repositories for radioactive waste. These repositories can have an impact on future generations for a period of time orders of magnitude longer than any known civilization. Several countries have considered copper as an outer corrosion barrier for canisters containing spent nuclear fuel. Among the many processes that must be considered in the safety assessments, radiation induced processes constitute a key-component. Here we show that copper metal immersed in water uptakes considerable amounts of hydrogen when exposed to γ-radiation. Additionally we show that the amount of hydrogen absorbed by copper depends on the total dose of radiation. At a dose of 69 kGy the uptake of hydrogen by metallic copper is 7 orders of magnitude higher than when the absorption is driven by H2(g) at a pressure of 1 atm in a non-irradiated dry system. Moreover, irradiation of copper in water causes corrosion of the metal and the formation of a variety of surface cavities, nanoparticle deposits, and islands of needle-shaped crystals. Hence, radiation enhanced uptake of hydrogen by spent nuclear fuel encapsulating materials should be taken into account in the safety assessments of nuclear waste repositories.

  • 252.
    Lousada, Claudio Miguel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Yang, Miao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Nilsson, Kristina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Catalytic decomposition of hydrogen peroxide on transition metal and lanthanide oxides2013In: Journal of Molecular Catalysis A: Chemical, ISSN 1381-1169, E-ISSN 1873-314X, Vol. 379, p. 178-184Article in journal (Refereed)
    Abstract [en]

    We have investigated the reactions of H2O2 with Fe2O3, CuO, HfO2, CeO2 and Gd 2O3 in aqueous solution. The reactions rate constants at room temperature were determined. From the temperature dependence of the rate constants we extracted the Arrhenius parameters and the standard enthalpies of activation for the reactions. In addition, we studied the dynamics of formation of the intermediate species formed during decomposition of H2O 2, the HO radical. The kinetic data for H2O2 reactivity and the yields of hydroxyl radical formation differ considerably between many of the materials studied. We compared the energetic and mechanistic data obtained in this work with literature data for a set of nine oxides in total. The Arrhenius pre-exponential factors normalized to surface area for the decomposition of H2O2 vary by nine orders of magnitude for some of the oxides investigated. This indicates that the surfaces of the oxides have very different catalytic capacity towards the decomposition of H 2O2. The standard enthalpies of activation for H 2O2 decomposition vary between 30 and 73 kJ mol -1, revealing also differences in the catalytic efficiency for the different materials. The mechanistic study consists of quantifying the HO radical scavenged by tris(hydroxymethyl)aminomethane (Tris) during the course of the decomposition of H2O2 for the whole set of oxides. The yields and dynamics of scavenging of HO• differ considerably between the oxides analyzed. Surprisingly, the time-independent plots of the amount of HO scavenged as a function of the conversion of H2O 2 reveals that during the decomposition of H2O2 there are turnover points where the amount of HO scavenged by Tris suffers a sudden increase. The location of these points and the curvatures of the plots at the near-neighbours is considerably different for the different materials.

  • 253.
    Lousada, Cláudio M.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Fernandes, Ricardo M. F.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Tarakina, Nadezda V.
    Soroka, Inna L.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Synthesis of copper hydride (CuH) from CuCO3·Cu(OH)2 – a path to electrically conductive thin films of Cu2017In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 46, no 20, p. 6533-6543Article in journal (Refereed)
    Abstract [en]

    The most common synthesis methods for copper hydride (CuH) employ hard ligands that lead to the formation of considerable amounts of metallic Cu as side-product. Here we explore a synthesis method for CuH(s) through the reaction of CuCO3 center dot Cu(OH)(2)(s) with hypophosphorous acid (H3PO2) in solution, via the formation of the intermediate Cu(H2PO2)(2)(aq) complex. The reaction products were characterized with XRD, FTIR and SEM at different reaction times, and the kinetics of the transformation of Cu(H2PO2)(2)(aq) to CuH(s) were followed with NMR and are discussed. We show that our synthesis method provides a simple way for obtaining large amounts of CuH(s) even when the synthesis is performed in air. Compared to the classic Wurtz method, where CuSO4 is used as an initial source of Cu2+, our synthesis produces CuH particles with less metallic Cu side-product. We attribute this to the fact that our reaction medium is free from the hard SO42- ligand that can disproportionate Cu(I). We discuss a mechanism for the reaction based on the known reactivity of the reagents and intermediates involved. We explored the possibility of using CuH(s) for making electrically conductive films. Tests that employed water-dispersed CuH particles show that this compound can be reduced with H3PO2 leading to electrically conductive thin films of Cu. These films were made on regular office paper and were found to be Ohmic conductors even after several weeks of exposure to ambient conditions. The fact that the synthesis reported here produces large amounts of CuH particles in aqueous media, with very little impurities, and the fact that these can then be converted to a stable electrically conductive film can open up new applications for CuH such as for printing electrically conductive films or manufacturing surface coatings.

  • 254.
    Lousada, Cláudio M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Trummer, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Reactivity of H2O2 towards different UO2-based materials: The relative impact of radiolysis products revisited2013In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 434, no 1/3, p. 434-439Article in journal (Refereed)
    Abstract [en]

    The reactivity of doped UO2 such as SIMFUEL towards H2O2 has been shown to be fairly similar to that of pure UO2. However, the oxidative dissolution yield, i.e. the ratio between the amount of dissolved uranium and the amount of consumed H2O2 is significantly lower for doped UO2. In this work we have studied the mechanistic difference between SIMFUEL and pure UO2. H2O2 can be catalytically decomposed on UO2 in competition with the redox process in which U(IV) is oxidized. The latter process leads to the dissolution of oxidized uranium. The first step in the catalytic decomposition is the formation of hydroxyl radicals. The presence of hydroxyl radicals was verified using Tris buffer as a radical scavenger. For both UO2 and SIMFUEL pellets, significant amounts of hydroxyl radicals were formed. The results also show that the difference in dissolution yield between the two materials can mainly be attributed to differences in the redox reactivity. Based on this, the rate constants for electron transfer were revised and the relative impact of the radiolytic oxidants in oxidative dissolution of UO2 and SIMFUEL pellets were calculated. The impact of H2O2 is shown to be slightly reduced.

  • 255.
    Lousada Patricio, Cláudio Miguel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Adam Johannes
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Reactivity of metal oxide clusters with hydrogen peroxide and water: a DFT study evaluating the performance of different exchange-correlation functionals2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 15, p. 5539-5552Article in journal (Refereed)
    Abstract [en]

    We have performed a density functional theory (DFT) investigation of the interactions of H2O2, H2O and HO radicals with clusters of ZrO2, TiO2 and Y2O3. Different modes of H2O adsorption onto the clusters were studied. In almost all the cases the dissociative adsorption is more exothermic than molecular adsorption. At the surfaces where H2O has undergone dissociative adsorption, the adsorption of H2O2 and the transition state for its decomposition are mediated by hydrogen bonding with the surface HO groups. Using the functionals B3LYP, B3LYP-D and M06 with clusters of 26 and 8 units of ZrO2, the M06 functional performed better than B3LYP in describing the reaction of decomposition of H2O2 and the adsorption of H2O. Additionally, we investigated clusters of the type (ZrO2)2, (TiO2)2 and (Y2O3) and the performance of the functionals B3LYP, B3LYP-D, B3LYP*, M06, M06-L, PBE0, PBE and PWPW91 in describing H2O2, H2O and HO˙ adsorption and the energy barrier for decomposition of H2O2. The trends obtained for HO˙ adsorption onto the clusters are discussed in terms of the ionization energy of the metal cation present in the oxide. In order to correctly account for the existence of an energy barrier for the decomposition of H2O2, the functional used must include Hartree-Fock exchange. Using minimal cluster models, the best performance in describing the energy barrier for H2O2 decomposition was obtained with the M06 and PBE0 functionals - the average absolute deviations from experiments are 6 kJ mol(-1) and 5 kJ mol(-1) respectively. With the M06 functional and a larger monoclinic (ZrO2)8 cluster model, the performance is in excellent agreement with experimental data. For the different oxides, PBE0 was found to be the most effective functional in terms of performance and computational time cost.

  • 256.
    Lousada Patrício, Cláudio Miguel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Reactions of aqueous radiolysis products with oxide surfaces: An experimental and DFT study2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The reactions between aqueous radiolysis products and oxide surfaces are important in nuclear technology in many ways. In solid-liquid systems, they affect (and at the same time are dependent on) both the solution chemistry and the stability of materials under the influence of ionizing radiation. The stability of surface oxides is a factor that determines the longevity of the materials where such oxides are formed. Additionally, the aqueous radiolysis products are responsible for corrosion and erosion of the materials.

      In this study, the reactions between radiolysis products of water – mainly H2O2 and HO radicals – with metal, lanthanide and actinide oxides are investigated. For this, experimental and computational chemistry methods are employed. For the experimental study of these systems it was necessary to implement new methodologies especially for the study of the reactive species – the HO radicals. Similarly, the computational study also required the development of models and benchmarking of methods. The experiments combined with the computational chemistry studies produced valuable kinetic, energetic and mechanistic data.

      It is demonstrated here that the HO radicals are a primary product of the decomposition of H2O2. For all the materials, the catalytic decomposition of H2O2 consists first of molecular adsorption onto the surfaces of the oxides. This step is followed by the cleavage of the O-O bond in H2O2 to form HO radicals. The HO radicals are able to react further with the hydroxylated surfaces of the oxides to form water and a surface bound HO center. The dynamics of formation of HO vary widely for the different materials studied. These differences are also observed in the activation energies and kinetics for decomposition of H2O2. It is found further that the removal of HO from the system where H2O2 undergoes decomposition, by means of a scavenger, leads to the spontaneous formation of H2.

      The combined theoretical-experimental methodology led to mechanistic understanding of the reactivity of the oxide materials towards H2O2 and HO radicals. This reactivity can be expressed in terms of fundamental properties of the cations present in the oxides. Correlations were found between several properties of the metal cations present in the oxides and adsorption energies of H2O, adsorption energies of HO radicals and energy barriers for H2O2 decomposition. This knowledge can aid in improving materials and processes important for nuclear technological systems, catalysis, and energy storage, and also help to better understand geochemical processes.

  • 257.
    Lowe, Troy A.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hedberg, Jonas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Lundin, Maria
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Wold, Susanna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Chemical Speciation Measurements of Silver Ions in Alkaline Carbonate Electrolytes Using Differential Pulse Stripping Voltammetry on Glassy Carbon Compared With Ion Selective Electrode Measurements2013In: International Journal of Electrochemical Science, ISSN 1452-3981, E-ISSN 1452-3981, Vol. 8, no 3, p. 3851-3865Article in journal (Refereed)
    Abstract [en]

    Given the increasing incorporation of silver nanoparticles as an antibacterial additive in washing machines and textiles, sensitive methods for accurate determination of Ag+ ions in laundry relevant electrolytes (alkaline carbonate) are required. The most widely reported method, the silver ion selective electrode (ISE), lacked sensitivity and accuracy and was affected by the concentration of Na2CO3 in solution. Differential pulse stripping voltammetry (DPSV) on glassy carbon electrodes (GCE) was therefore investigated as an alternative technique. Surface preparation of the GCE surface was essential and a suitable procedure was developed. A linear response was observed from 0 to 180 mg L-1 with a lower detection limit of 500 ng L-1 (5 nM). DPSV was shown to be significantly more sensitive and accurate in determining the Ag+ activity than the silver ISE technique, particularly below 200 nM.

  • 258.
    Mikkonen, Saara
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Electrophoretic focusing in microchannels combined with mass spectrometry: Applications on amyloid beta peptides2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Analysis of low-abundance components in small samples remains a challenge within bioanalytical chemistry, and new techniques for sample pretreatments followed by sensitive and informative detection are required. In this thesis, procedures for preconcentration and separation of proteins and peptides in open microchannels fabricated on silicon microchips are presented. Analyte electromigration was induced by applying a voltage along the channel length, and detection was performed either by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) within the open channel, or by sampling a nL fraction containing the preconcentrated analytes from the channel for subsequent nano-electrospray ionization- (nESI-) or MALDI-MS. Utilizing solvent evaporation from the open system during sample supply, sample volumes exceeding the 25-75 nL channel volume could be analyzed. For preconcentration/separation of components in the discrete channel volume a lid of inert fluorocarbon liquid was used for evaporation control.

    In Papers I and II, aqueous, carrier-free solutions of proteins and peptides were analyzed, and the method was successfully applied for fast and simple preconcentration of amyloid beta (Aβ) peptides, related to Alzheimer’s disease.

    The impact of possible impurities in the analysis of carrier-free solutions was investigated in Paper III with the 1D simulation software GENTRANS, and a method for open-channel isoelectric focusing in a tailor-made pH gradient was developed. The latter approach was used in Paper IV for preconcentration and purification of Aβ peptides after immunoprecipitation from cerebrospinal fluid and blood plasma, followed by MALDI-MS from a micropillar chip.

    Paper V includes simulations of an isotachophoretic strategy for selective enrichment of Aβ peptides. GENTRANS simulations were used to select the electrolyte composition, and 2D simulations in a geometry suitable for on-chip implementation were performed using COMSOL Multiphysics.

  • 259.
    Mikkonen, Saara
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sample preconcentration in open microchannels: Combinations with MALDI and nano-ESI mass spectrometry and computer simulations2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis a novel concept for preconcentration of biomolecules in open microchannels is presented. The preconcentration is based on electromigration of charged analytes, and detection is performed with matrix-assisted laser desorption/ionization (MALDI) or nano-electrospray ionization (nESI) mass spectrometry (MS).

    Analysis of minute volumes of low-concentration samples is an important and challenging task within several fields of chemistry, biology and medicine. In bioanalytical chemistry in particular, sample pretreatment procedures including preconcentration must frequently be applied. Due to the often small available sample volumes, it is advantageous to perform these pretreatments in microfluidic devices. Moreover, since MS in many cases is the detection method of choice, there is a requirement for developing suitable interfacing techniques between the microchip and MS.

    In Paper I, the preconcentration concept is presented; silicon microchips with parallel open channels were used. The channels have a rectangular shape and are 1 cm long, 50-150 µm wide and 50 µm deep, yielding a total channel volume of 25-75 nL. By supplying sample to the channel and applying a voltage over the channel length, charged analytes will migrate towards the oppositely charged electrode and become concentrated. In Paper I, detection was performed by using the open microchannel directly as a MALDI-target. To achieve this, matrix solution was added to the channel after the preconcentration with electrospray matrix deposition. Using this approach, preconcentration of cytochrome c was achieved, and the lowest initial protein concentration successfully detected after preconcentration was 1 nM. The trypsin digest of cytochrome c was also analyzed, and the peptides were preconcentrated at different ends of the channel based on charge.

    Other means of coupling the preconcentration to MS, by extracting a nanovolume of the preconcentrated sample from the open channel, are presented in Paper II. The extracted samples could either be analyzed directly using nESI- or MALDI-MS, or subjected to further pretreatment (such as enzymatic digestion) in a nanodroplet under a fluorocarbon (FluorinertPTMP) liquid lid prior to MS-analysis. Furthermore, in Paper II the method was applied on an amyloid beta cell culture. This resulted in that peptides not detectable without preconcentration easily could be detected with MALDI-MS in nanodroplets extracted from the microchannels after preconcentration.

    Paper III includes theoretical simulations of the preconcentration procedure obtained using the electrophoresis simulator GENTRANS. The experimental results from Paper I are compared to simulations of similar systems, and simulations of an isoelectric focusing (IEF) procedure for proteins or peptides in a mixture of amino acids, are presented. The IEF procedure is to be used in the open microchannels in future experimental work.

  • 260.
    Mikkonen, Saara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ekström, Henrik
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Jacksén, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Emmer, Åsa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Selective enrichment of amyloid beta peptides using isotachophoresisManuscript (preprint) (Other academic)
  • 261.
    Mikkonen, Saara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jacksén, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Emmer, Åsa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Mass spectrometric analysis of nanoscale sample volumes extracted from open microchannels after sample preconcentration applied on amyloid beta peptides2014In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 406, no 14, p. 3521-3524Article in journal (Refereed)
    Abstract [en]

    A new instrumental concept for extraction of nanovolumes from open microchannels (dimensions 150 mu m x 50 mu m, length 10 mm) manufactured on silicon microchips has been used in combination with a previously developed method for preconcentrating proteins and peptides in the open channels through electromigration. The extracted nanovolumes were further analyzed using nanoelectrospray ionization (nESI) or matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) directly or with subsequent enzymatic protein digestion in a nanodroplet prior to the MS analysis. Preconcentration of the samples resulted in a 15-fold sensitivity increase in nESI for a neurotensin solution, and using MALDI-MS, amyloid beta (A beta) peptides could be detected in concentrations down to 1 nM. The method was also successfully applied for detection of cell culture A beta.

  • 262.
    Mikkonen, Saara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jacksén, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Roeraade, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Thormann, Wolfgang
    University of Bern, Clinical Pharmacology Laboratory, Institute for Infectious Diseases.
    Emmer, Åsa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Microfluidic Isoelectric Focusing of Amyloid Beta Peptides Followed by Micropillar-Matrix-Assisted Laser Desorption Ionization-Mass Spectrometry2016In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882Article in journal (Refereed)
    Abstract [en]

    A novel method for preconcentration and purification of the Alzheimer’s disease related amyloid beta (Aβ) peptides by isoelectric focusing (IEF) in 75 nL microchannels combined with their analysis by micropillar-matrix-assisted laser desorption ionization-time-of-flight-mass spectrometry (MALDI-TOF-MS) is presented. A semiopen chip-based setup, consisting of open microchannels covered by a lid of a liquid fluorocarbon, was used. IEF was performed in a mixture of four small and chemically well-defined amphoteric carriers, glutamic acid, aspartyl-histidine (Asp-His), cycloserine (cSer), and arginine, which provided a stepwise pH gradient tailored for focusing of the C-terminal Aβ peptides with a pI of 5.3 in the boundary between cSer and Asp-His. Information about the focusing dynamics and location of the foci of Aβ peptides and other compounds was obtained using computer simulation and by performing MALDI-MS analysis directly from the open microchannel. With the established configuration, detection was performed by direct sampling of a nanoliter volume containing the focused Aβ peptides from the microchannel, followed by deposition of this volume onto a chip with micropillar MALDI targets. In addition to purification, IEF preconcentration provides at least a 10-fold increase of the MALDI-MS-signal. After immunoprecipitation and concentration of the eluate in the microchannel, IEF-micropillar-MALDI-MS is demonstrated to be a suitable platform for detection of Aβ peptides in human cerebrospinal fluid as well as in blood plasma.

  • 263.
    Mikkonen, Saara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Rokhas, Maria Khihon
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jacksén, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Emmer, Åsa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sample preconcentration in open microchannels combined with MALDI-MS2012In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 33, no 22, p. 3343-3350Article in journal (Refereed)
    Abstract [en]

    In this work, a method for preconcentrating samples in 1 cm long, 50-150 μm wide open microchannels is presented. Platinum electrodes were positioned at the channel ends, voltage was applied, and charged analyte was preconcentrated at the oppositely charged side during continuous supply of sample. The preconcentration was initially studied in a closed system, where an influence on the analyte position from a pH gradient, generated by water electrolysis, was observed. In the open channel, the analyte distribution after preconcentration was evaluated using MALDI-MS with the channel as MALDI target. MALDI matrix was applied with an airbrush or by electrospray matrix deposition and by using the latter technique higher degrees of crystallization in the channels were obtained. After preconcentrating a 1 nM cytochrome c solution for 5 min, corresponding to a supplied amount of 1.25 fmol, a signal on the cathodic channel end could be detected. When a solution of cytochrome c trypsin digest was supplied, the peptides were preconcentrated at different positions along the channel depending on their charge.

  • 264.
    Mikkonen, Saara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Thormann, Wolfgang
    Emmer, Åsa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Computer simulations of sample preconcentration in carrier-free systems and isoelectric focusing in microchannels using simple ampholytes2015In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 36, no 19, p. 2386-2395Article in journal (Refereed)
    Abstract [en]

    In this work, electrophoretic preconcentration of protein and peptide samples in microchannels was studied theoretically using the 1D dynamic simulator GENTRANS, and experimentally combined with MS. In all configurations studied, the sample was uniformly distributed throughout the channel before power application, and driving electrodes were used as microchannel ends. In the first part, previously obtained experimental results from carrier-free systems are compared to simulation results, and the effects of atmospheric carbon dioxide and impurities in the sample solution are examined. Simulation provided insight into the dynamics of the transport of all components under the applied electric field and revealed the formation of a pure water zone in the channel center. In the second part, the use of an IEF procedure with simple well defined amphoteric carrier components, i.e. amino acids, for concentration and fractionation of peptides was investigated. By performing simulations a qualitative description of the analyte behavior in this system was obtained. Neurotensin and [Glu1]-Fibrinopeptide B were separated by IEF in microchannels featuring a liquid lid for simple sample handling and placement of the driving electrodes. Component distributions in the channel were detected using MALDI- and nano-ESI-MS and data were in agreement with those obtained by simulation. Dynamic simulations are demonstrated to represent an effective tool to investigate the electrophoretic behavior of all components in the microchannel.

  • 265. Mille, Christian
    et al.
    Corkery, Robert W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    A structural and thermal conductivity study of highly porous, hierarchical polyhedral nanofoam shells made by condensing silica in microemulsion films on the surface of emulsified oil drops2013In: J MATER CHEM A, ISSN 2050-7488, Vol. 1, no 5, p. 1849-1859Article in journal (Refereed)
    Abstract [en]

    Light-weight solid foams are utilized in applications such as packaging and insulation mainly due to their intrinsically high porosity, low relative density and associated mechanical and transport properties. Here hollow core spherical shells are prepared with walls made of a polyhedral silica nanofoam with open cells. A microemulsion film at the oil-water interface of oil droplets is used as a soft structural template for the condensation of soluble silica species. The microemulsion sets the length scale of the monodisperse silica nanofoam cells, and the emulsion droplets set the micron-scale dimensions of the polydisperse spherical shells. Porosity is achieved by removing the templates and oils, leaving pure low-density silica. This results in a hierarchically structured, highly porous shell foam material that packs into beds with a measured porosity of approximately 97.3%, well into the range of silica aerogels. Using a combination of electron microscopy, small-angle synchrotron X-ray diffraction and nitrogen physisorption, an accurate structural model for the nanofoam shells is constructed. The material is shown to be comprised of open-cell foams that are structurally analogous to dry polyhedral soap froths having minimal surface partitions, and Plateau boundaries. The primary polyhedral nanofoam cells are 30 nm in diameter connected by 7 nm cylindrical windows. These nanofoams form spherical monolithic shells with volume average mean diameter of 41 microns and shell thickness of 0.7 microns. Simple models for the thermal conductivity of these nanofoam shell materials are constructed that include accounting for the nanoscale effects on gaseous and solid thermal conductivity. These are compared to the measured value of 0.041 W m(-1) K-1. These materials represent new structures in the family of self-assembled, highly porous silica materials and are potentially useful in packaging and insulation and other applications due to their light weight and/or intrinsically low thermal conductivity and associated mechanical and transport properties.

  • 266. Mille, Christian
    et al.
    Tyrode, Eric C.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Corkery, Robert W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    3D titania photonic crystals replicated from gyroid structures in butterfly wing scales: approaching full band gaps at visible wavelengths2013In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, no 9, p. 3109-3117Article in journal (Refereed)
    Abstract [en]

    3D titania photonic crystals are replicated from single gyroid structures found in the butterfly Callophrys rubi. Photonic crystals were characterised using SEM imaging, X-ray and Raman scattering and reflection spectroscopy. The overall symmetry and topology of the original single gyroid structures is replicated with high fidelity. Titania replicas display photonic responses that are thermal history dependent. Replicas treated at 700 degrees C, show up to 96% reflectivity at similar to 505 nm, while at lower and higher treatment temperatures the photonic response was not as pronounced. Simulated band structures fitted to the observed spectral reflectivity data constrain the solid volume fractions and dielectric constants of the replicas. The titania photonic crystals were also found to be optically active, with both left- and right-handed single gyroids contributing to the chiral response. The 3D titania photonic crystals replicated here have nearly complete overlapping of partial band gaps, strongly suggesting that materials with full photonic band gaps are experimentally within reach using the general replication approach reported here.

  • 267.
    Mohammadi, Maryam
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Forsberg, Kerstin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    De La Cruz, Joaquin Martinez
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Separation of Nd(III), Dy(III) and Y(III) by solvent extraction using D2EHPA and EHEHPA2015In: Hydrometallurgy, ISSN 0304-386X, E-ISSN 1879-1158, Vol. 156, p. 215-224Article in journal (Refereed)
    Abstract [en]

    The equilibrium separation of trivalent rare earth elements (Nd(III), Dy(III), and Y(III)) from hydrochloric acid solution by di-(2-ethylhexyl) phosphoric acid (D2EHPA) and 2-ethylhexylphosphonic acid mono-2-ethyl hexyl ester (EHEHPA) separately and in mixtures has been studied. The effect of extractant concentration, extractant mixture composition and solution acidity has been investigated. The results show that a mixture of D2EHPA and EHEHPA provide a better separation of Y(III) from Dy(III) when the total extractant concentration is 0.06 and 0.09 mol/L, while the separation is better using pure EHEHPA at higher extractant concentration (0.15 mol/L). The separation of Nd(III) from Y(III) and Dy(III) is higher using pure D2EHPA (0.06 and 0.15 mol/L). The results show that for the complexation of the Nd(III) ions approx. 1-2 hydrogen ions/rare earth element (REE) ion are released to the aqueous phase upon binding approximately 1 extractant dimer on average. For the complexation of Y(III) and Dy(III) ions 2-3 hydrogen ions are released upon binding approximately two extractant dimers on average. Accordingly, under the conditions of this work the complexation involves not only extractant molecule dimers but also monomers or aggregated REE species to some extent, and a fraction of the REE is extracted as chloride complexes. (C) 2015 Elsevier B.V. All rights reserved.

  • 268. Nadiv, Roey
    et al.
    Ferreira Fernandes, Ricardo Manuel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ochbaum, Guy
    Dai, Jing
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Buzaglo, Matat
    Varenik, Maxim
    Biton, Ronit
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Regev, Oren
    Polymer nanocomposites: insights on rheology, percolation, jamming and molecular mobilityManuscript (preprint) (Other academic)
    Abstract [en]

    Carbon nanotubes (CNTs) loading in a polymer matrix strongly affect the rheological behavior and in turn hamper the overall performance of the composite. The majority of the research in this topic has focused on bulk rheological properties, while here we employ NMR diffusion experiments to explore the mobility (diffusivity) of epoxy molecules when loaded with CNTs. Rheology and light microscopy indicate percolation, or jamming events of CNT aggregates, caging a substantial amount of epoxy molecules while small angle X-ray scattering indicates rearrangements of epoxy molecules in the vicinity of the nanotubes. NMR diffusion experiments distinguish between the diffusion of the caged molecules and that of the free ones, and relate the fraction of the former to the system viscosity. These findings demonstrate the utility of NMR diffusion experiments as an additional method applied to the rheological behavior of polymer mixtures.

  • 269. Niga, Petru
    et al.
    Hansson-Mille, Petra
    Swerin, Agne
    Claesson, Per
    Schoelkopf, Joachim
    Gane, Patrick
    Dai, Jing
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furo, Istvan
    Campbell, Richard
    Johnson, Magnus
    Propofol adsorption at the air/water interface: a combined vibrational sum frequency spectroscopy, nuclear magnetic resonance and neutron reflectometry studyManuscript (preprint) (Other academic)
    Abstract [en]

    Propofol interaction with cell membrane has remarkable influence on neuronal function, yet data regarding its behaviour at an interface is still scarce. Here we present the results of propofol adsorption at the air/water interface studied by means of vibrational sum frequency spectroscopy (VSFS), neutron reflectometry (NR), and surface tensiometry. VSFS was utilized to elucidate the orientation change of propofol at the surface as a function of concentration, and the water of hydration was studied by probing the OH vibrational region of the spectrum in two different polarisation combinations. Data show that propofol adsorbs at the air/water interface in an ordered fashion showing strong interactions with the water of hydration, as well as weak interactions with water in the proximity of the hydrocarbon parts of the molecule. In the concentration range studied (0 – 0.89 mM) there is almost no change in the orientation adopted at the interface. NR shows that propofol forms a dense monolayer with a thickness of 4.8 Å, and this result is consistent with a limiting area per molecule equivalent to a close-packed monolayer as demonstrated by surface tensiometry. The possibility that islands or multilayers of propofol form at the air/water interface is therefore excluded. Additionally, the ability of propofol to form associations/multimeric structures in water was studied using nuclear magnetic resonance (NMR). The 1H NMR chemical shifts recorded indicate that propofol does not form dimers or multimers in bulk water (D2O).

  • 270.
    Nilsson, Kristina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Oxidative dissolution of doped UO2 and H2O2 reactivity towards oxide surfaces: A kinetic and mechanistic study2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Oxidative dissolution of std. UO2 and UO2 doped with Cr2O3 and Al2O3, i.e. ADOPT, induced by H2O2 and γ radiation has been the main focus in this licentiate thesis. The catalytic decomposition of H2O2 on oxides like Gd2O3, HfO2, CeO2, Fe2O3 and CuO were also investigated.

    A kinetic study was performed by determining first and second order rate constants together with Arrhenius parameters for the decomposition of H2O2. The reactivity of H2O2 towards the oxides mentioned was observed to differ significantly despite their similarities. In the mechanistic study, the yields and dynamics of the formation of the intermediate hydroxyl radical from the decomposition of H2O2 was determined for the oxides and found to differ considerably. A turnover point could be found for most of oxides studied, i.e. an increase in the rate of hydroxyl radical scavenging after a specific amount of consumed H2O2.

    The reactivity of the std. UO2 and ADOPT towards H2O2 was similar to what was observed for other UO2-based materials in previous studies. The oxidative dissolution in radiation experiments showed a slight but significant difference. This was attributed to a difference in exposed surface area instead of an effect of doping. The difference in oxidative dissolution yield was too small to be significant which supports the previous conclusion.

    Leaching experiments using spent nuclear fuel were also performed on the two types of fuel showing the same behavior as the unirradiated pellets, i.e., a slightly lower 238U release from ADOPT. The difference was attributed to difference in exposed surface area. The release of fission products with low UO2 solubility displayed a higher release from ADOPT which was attributed to a difference in matrix solubility. Cs was released to a larger extent from std. UO2. This is attributed to the larger grain size of ADOPT, extending the diffusion distance. The release of lanthanides and actinides was slightly higher for the conventional UO2, nevertheless the difference was relatively small.

  • 271.
    Nilsson, Kristina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Roth, O.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Oxidative dissolution of ADOPT compared to standard UO2 fuel2017In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 488, p. 123-128Article in journal (Refereed)
    Abstract [en]

    In this work we have studied oxidative dissolution of pure UO2 and ADOPT (UO2 doped with Al and Cr) pellets using H2O2 and gammaradiolysis to induce the process. There is a small but significant difference in the oxidative dissolution rate of UO2 and ADOPT pellets, respectively. However, the difference in oxidative dissolution yield is insignificant. Leaching experiments were also performed on in-reactor irradiated ADOPT and UO2 pellets under oxidizing conditions. The results indicate that the U(VI) release is slightly slower from the ADOPT pellet compared to the UO2. This could be attributed to differences in exposed surface area. However, fission products with low UO2 solubility display a higher relative release from ADOPT fuel compared to standard UO2-fuel. This is attributed to a lower matrix solubility imposed by the dopants in ADOPT fuel. The release of Cs is higher from UO2 which is attributed to the larger grain size of ADOPT. © 2017 Elsevier B.V.

  • 272.
    Nilsson, Kristina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Roth, Olivia
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Oxidative dissolution of ADOPT compared to standard UO2 fuelManuscript (preprint) (Other academic)
  • 273.
    Norrfors, Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Stability and sorption capacity of montmorillonite colloids: Investigation of size fractional differences and effects of γ-irradiation2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bentonite clay is intended to form one of the barriers in most repositories of spent nuclear fuel located in granite. One important function of the bentonite barrier is to retard transport of radionuclides in the event of waste canister failure. Bentonite has a high sorption capacity of cations and its main constituent is montmorillonite. In contact with groundwater of low ionic strength, montmorillonite colloids can be released from bentonite and thereby control transport of radionuclides sorbed onto the colloids.

    In colloid transport in bedrock fractures, size separation of clay colloids may occur due to physical and chemical interactions with the bedrock fracture surface. This may enhance or retard the overall transport of radionuclides, depending on the sorption capacities and stability of the differently sized clay colloids. The bentonite barrier will be exposed to γ-radiation from the spent nuclear fuel. Irradiation affects surface-related properties of bentonite. If an average sorption capacity value cannot be used for all colloid sizes or if sorption is affected by exposure to γ-irradiation, corrected sorption capacity values would give higher resolution in current reactive transport models.

    In order to study the size separation process, a protocol was developed and successfully applied to fractionate montmorillonite into different-sized colloid suspensions by means of sequential or direct centrifugation. The stability and sorption capacity were studied using these fractions. Both stability and sorption capacity were found to be similar for all colloid sizes.

    Bentonite exposed to γ-radiation sorbed less divalent cations with increasing radiation dose. The effect was not large enough to have any impact on diffusion. The presence of bentonite enhanced irradiation-induced corrosion of copper under anaerobic atmosphere.

    An average sorption capacity value for montmorillonite can be used for all colloid sizes in reactive transport models. The effect of γ-irradiation on sorption capacity is sufficiently large to require consideration in transport modelling.

  • 274.
    Norrfors, Karin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Bouby, Muriel
    Heck, Stephanie
    Finck, Nicolas
    Marsac, Rémi
    Schäfer, Thorsten
    Geckeis, Horst
    Wold, Susanna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Montmorillonite colloids I: Characterization and stability ofsuspensions with different size fractionsManuscript (preprint) (Other academic)
  • 275.
    Norrfors, Karin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Bouby, Muriel
    Luetzenkirchen, Johannes
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Wold, Susanna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Smectite and latex colloid agglomeration at high ionic strength: Is there any effect of particle size?Manuscript (preprint) (Other academic)
  • 276.
    Norrfors, Karin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Bouby, Muriel
    Marsac, Rémi
    Heck, Stephanie
    Schäfer, Thorsten
    Geckeis, Horst
    Wold, Susanna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Montmorillonite colloids II: Dependency of Colloidal size on Sorption of RadionuclidesManuscript (preprint) (Other academic)
  • 277.
    Norrfors, Karin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Bouby, Muriel
    Marsac, Rémi
    Heck, Stephanie
    Schäfer, Thorsten
    Geckeis, Horst
    Wold, Susanna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Montmorillonite colloids III: Influence of Colloidal Size onthe Sorption Reversibility of RadionuclidesManuscript (preprint) (Other academic)
  • 278.
    Norrfors, Karin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kessler, Amanda
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Björkbacka, Åsa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Wold, Susanna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Radiation induced corrosion of copper in bentonite-water systems under anaerobic conditionsManuscript (preprint) (Other academic)
  • 279.
    Norrfors, Knapp Karin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. Karlsruhe Institute of Technology (KIT), Germany.
    Bouby, Muriel
    Heck, Stephanie
    Finck, Nicolas
    Marsac, Rerni
    Schaefer, Thorsten
    Geckeis, Horst
    Wold, Susanna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Montmorillonite colloids: I. Characterization and stability of dispersions with different size fractions2015In: Applied Clay Science, ISSN 0169-1317, E-ISSN 1872-9053, Vol. 114, p. 179-189Article in journal (Refereed)
    Abstract [en]

    Bentonite is planned to be used as a technical barrier in the final storage of spent nuclear fuel and high level vitrified waste. In contact with ground water of low ionic strength, montmorillonite colloids may be released from the bentonite buffer and thereby enhance the transport of radionuclides (RNs) sorbed: In the present case, clay colloids represent aggregates of several clay mineral layers. It is of major importance to determine RN sorption properties for different sizes of montmorillonite aggregates, since size fractionation may occur during particle transport in natural media. In this study, a protocol for size fractionation of clay aggregates is developed, by sequential and direct centrifugation, in the presence and absence of organic matter. Seven colloidal fractions of different mean aggregate sizes are obtained ranging, when considering the mean equivalent hydrodynamic sphere diameter (ESD), from similar to 960 nm down to similar to 85 nm. Applying mathematical treatments (Jennings and Parslow, 1988) and approximating the clay aggregates to regular disc-shaped stacks of clay mineral sheets result in mean surface diameters varying from similar to 1.5 mu m down to similar to 190 nm. All these colloidal fractions are characterized by XRD, IC and ICP-OES where they are found to have the same chemical composition. The number of edge sites (aluminol and silanol) is estimated (in mol/kg) for each colloidal fraction according to (Tournassat et al., 2003). It is calculated from the mean particle sizes obtained from AsFlFFF and PCS measurements, where the clay aggregates are approximated to regular disc-shaped stacks of clay mineral sheets. The estimated number of edge sites varies significantly for the different clay dispersions. In addition, stability studies using the various clay colloidal fractions are performed by the addition of NaCl, CaCl2 or MgCl2, in the presence or absence of organic matter, where no difference in stability is found.

  • 280.
    Norrfors, Knapp Karin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Karlsruhe Institute of Technology (KIT), Germany.
    Marsac, Remi
    Bouby, Muriel
    Heck, Stephanie
    Wold, Susanna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Luetzenkirchen, Johannes
    Schäfer, Thorsten
    Montmorillonite colloids: II. Colloidal size dependency on radionuclide adsorption2016In: Applied Clay Science, ISSN 0169-1317, E-ISSN 1872-9053, Vol. 123, p. 292-303Article in journal (Refereed)
    Abstract [en]

    Bentonite is a strong radionuclide (RN) adsorbent. As a consequence, it is proposed as one of the engineered safety barriers in many nuclear waste disposal concepts in granite formations. Despite the many beneficial effects of bentonite, in contact with groundwater of low ionic strength montmorillonite colloids may be released from the bentonite buffer and transported towards the biosphere carrying the RNs bound to it. During the transport of colloids in bedrock fractures, size separation of clay colloids may occur, which may further affect RN mobility. In this work, RN adsorption (Th(IV), U(VI), Np(V), Tc(VII) and Pu(IV)) onto size fractionated montmorillonite colloids was studied in a synthetic, carbonated groundwater. Fractionation was done by simple settling procedures and sequential centrifugation. We combined batch adsorption experiments and geochemical modelling for the adsorption studies. U(VI), Np(V) and Tc(VII) did not adsorb to montmorillonite in the synthetic groundwater. Adsorption of Th(IV) and Pu(IV) is strong but, within experimental uncertainties, not significantly affected by the fractionation process. Montmorillonite colloids obtained by fractionation of the raw clay material but in the presence of organic matter during the initial separation step present significantly reduced uptake of Th and Pu. Based on the results, implementation of an "average log K-D" (i.e. average distribution coefficients) for all colloidal sizes in reactive transport modelling codes would be acceptable.

  • 281.
    Oyarce, Alejandro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Hussami, Linda L.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Corkey, Robert W.
    Lagergren, Carina
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Polyhedral Carbon Nanoforms as catalyst support in a Proton Exchange Membrance cathodeManuscript (preprint) (Other academic)
  • 282.
    Pagès, Guilhem
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furó, István
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Suppressing magnetization exchange effects in stimulated-echo diffusion experiments2013In: Journal of magnetic resonance, ISSN 1090-7807, E-ISSN 1096-0856, Vol. 234, p. 35-43Article in journal (Refereed)
    Abstract [en]

    Exchange of nuclear magnetization between spin pools, either by chemical exchange or by cross-relaxation or both, has a significant influence on the signal attenuation in stimulated-echo-type pulsed field gradient experiments. Hence, in such cases the obtained molecular self-diffusion coefficients can carry a large systematic error. We propose a modified stimulated echo pulse sequence that contains T-2-filters during the z-magnetization store period. We demonstrate, using a common theoretical description for chemical exchange and cross-relaxation, that these filters suppress the effects of exchange on the diffusional decay in that frequent case where one of the participating spin pools is immobile and exhibits a short T-2. We demonstrate the performance of this experiment in an agarose/water gel. We posit that this new experiment has advantages over other approaches hitherto used, such as that consisting of measuring separately the magnetization exchange rate, if suitable by Goldman-Shen type experiments, and then correcting for exchange effects within the framework of a two-site exchange model. We also propose experiments based on selective decoupling and applicable in systems with no large T-2 difference between the different spin pools. (C) 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  • 283. Pankratova, Nadezda
    et al.
    Cuartero, Maria
    Jowett, Laura
    Howe, Ethan
    Gale, Philip A
    Bakker, Eric
    Crespo, Gaston A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Fluorinated tripodal receptors for potentiometric chloride detection in biological fluids2017In: Biosensors and Bioelectronics, ISSN 0956-5663, Vol. 99, p. 70-76Article in journal (Refereed)
    Abstract [en]

    Fluorinated tripodal compounds were recently reported to be efficient transmembrane transporters for a series of inorganic anions. In particular, this class of receptors has been shown to be suitable for the effective complexation of chloride, nitrate, bicarbonate and sulfate anions via hydrogen bonding. The potentiometric properties of urea and thiourea-based fluorinated tripodal receptors are explored here for the first time, in light of the need for reliable sensors for chloride monitoring in undiluted biological fluids. The ion selective electrode (ISE) membranes with tren-based tris-urea bis(CF3) tripodal compound (ionophore I) were found to exhibit the best selectivity for chloride over major lipophilic anions such as salicylate (log K-Cl-/Sal-(pot) = + 1.0) and thiocyanate (log K-Cl-/SCN-(pot) = + 0.1). Ionophore I-based ISEs were successfully applied for chloride determination in undiluted human serum as well as artificial serum sample, the slope of the linear calibration at the relevant background of interfering ions being close to Nernstian (49.8 +/- 1.7 mV). The results of potentiometric measurements were confirmed by argentometric titration. Moreover, the ionophore I-based ISE membrane was shown to exhibit a very good long-term stability of potentiometric performance over the period of 10 weeks. Nuclear magnetic resonance (NMR) titrations, potentiometric sandwich membrane experiments and density functional theory (DFT) computational studies were performed to determine the binding constants and suggest 1:1 complexation stoichiometry for the ionophore I with chloride as well as salicylate.

  • 284. Pehrman, Reijo
    et al.
    Trummer, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Lousada, Claudio Miguel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    On the redox reactivity of doped UO2 pellets - Influence of dopants on the H2O2 decomposition mechanism2012In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 430, no 1-3, p. 6-11Article in journal (Refereed)
    Abstract [en]

    The reactivity of doped UO2 such as SIMFUEL, Y2O3 doped UO2 and Y2O3/Pd doped UO2 towards H2O2 has been shown to be fairly similar to that of pure UO2. However, the oxidative dissolution yield, i.e. the ratio between the amount of dissolved uranium and the amount of consumed H2O2 is significantly lower for doped UO2. The rationale for the observed differences in dissolution yield is a difference in the ratio between the rates of the two possible reactions between H2O2 and the doped UO2. In this work we have studied the effect of doping on the two possible reactions, electron-transfer and catalytic decomposition. The catalytic decomposition was studied by monitoring the hydroxyl radical production (the primary product) as a function of time. The redox reactivity of the doped pellets was studied by using MnO4- and IrCl62- as model oxidants, only capable of electron-transfer reactions with the pellets. In addition, the activation energies for oxidation of UO2 and SIMFUEL by MnO4- were determined experimentally. The experiments show that the rate of catalytic decomposition of H2O2 varies by 30% between the most and least reactive material. This is a negligible difference compared to the difference in oxidative dissolution yield. The redox reactivity study shows that doping UO2 influences the redox reactivity of the pellet. This is further illustrated by the observed activation energy difference for oxidation of UO2 and SIMFUEL by MnO4-. The redox reactivity study also shows that the sensitivity to dopants increases with decreasing reduction potential of the oxidant. These findings imply that the relative impact of radiolytic oxidants in oxidative dissolution of spent nuclear fuel must be reassessed taking the actual fuel composition into account.

  • 285. Pemberton, Nils
    et al.
    Gradén, Henrik
    Evertsson, Emma
    Bratt, Emma
    Lepistö, Matti
    Johannesson, Petra
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Synthesis and Functionalization of Cyclic Sulfonimidamides: A Novel Chiral Heterocyclic Carboxylic Acid Bioisostere2012In: ACS Medicinal Chemistry Letters, ISSN 1948-5875, E-ISSN 1948-5875, Vol. 3, no 7, p. 574-578Article in journal (Refereed)
    Abstract [en]

    An efficient synthesis of aryl substituted cyclic sulfonimidamides designed as chiral nonplanar heterocyclic carboxylic acid bioisosteres is described. The cyclic sulfonimidamide ring system could be prepared in two steps from a trifluoroacetyl protected sulfinamide and methyl ester protected amino acids. By varying the amino acid, a range of different C-3 substituted sulfonimidamides could be prepared. The compounds could be further derivatized in the aryl ring using standard cross coupling reactions to yield highly substituted cyclic sulfonimidamides in excellent yields. The physicochemical properties of the final compounds were examined and compared to those of the corresponding carboxylic acid and tetrazole derivatives. The unique nonplanar shape in combination with the relatively strong acidity (pK(a) 5-6) and the ease of modifying the chemical structure to fine-tune the physicochemical properties suggest that this heterocycle can be a valuable addition to the range of available carboxylic acid isosteres.

  • 286. Pettersson, Birgitta
    et al.
    Bergman, Jan
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Synthetic studies towards 1,5-benzodiazocines2013In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 69, no 12, p. 2647-2654Article in journal (Refereed)
    Abstract [en]

    Anthranilonitrile reacted with phenylmagnesium bromide to yield a dianion, which when heated (similar to 120 degrees C) yielded the condensation product 2-(2-aminophenyl)-2,4-dipheny1-1,2-dihydroquinazoline 8. This heterocycle, when treated with palladium acetate, was converted into 6,12-diphenyldibenzo[b,f][1,5] diazocine 9. Methylmagnesium bromide and anthranilonitrile, under similar conditions directly gave a nitrogen-bridged diazocine, whose structure was determined by X-ray crystallography and also proven to be an analogue of Troger's base. Acid-induced condensation of 2-amino-3-methoxybenzaldehyde gave the trimeric product 45 rather than a dibenzo[b,f][1,5]diazocine.

  • 287. Pettersson, Henrik
    et al.
    Nonomura, Kazuteru
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Hagfeldt, Anders
    Trends in patent applications for dye-sensitized solar cells2012In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 5, no 6, p. 7376-7380Article in journal (Refereed)
    Abstract [en]

    Dye-sensitized solar cell (DSC) technology has grown into a massive field of research and development with a fast increasing number of scientific publications and patent applications. We have created a database for patents and patent applications that deal with dye-sensitized solar cell technology. In this paper the database has been used to analyze the number of patent applications over time, as well as technical, organizational, and geographical trends in patent applications for dye-sensitized solar cells. Activity in relation to DSC patents seriously took off after the millennium, with the majority of DSC patent applications coming from Asia. Almost 90% of the documents in the database derive from Japan, China, and Korea. From a technical perspective, approximately 75% of the DSC patent applications deal with DSC materials, mainly semiconductor materials, dyes, electrolytes, and device substrates. The DSC patent situation is complex and we recommend any potential manufacturer of DSC devices and/or DSC components to carefully analyze their freedom-to-operate.

  • 288. Pietra, M. D.
    et al.
    Rexed, Ivan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Lagergren, Carina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    McPhail, S.
    Paoletti, C.
    Moreno, A.
    Experimental procedures for accelerated aging tests using MCFC button cells2013In: EFC 2013 - Proceedings of the 5th European Fuel Cell Piero Lunghi Conference, 2013, p. 363-364Conference paper (Refereed)
    Abstract [en]

    The aim of this work is to study whether the effects of electrolyte evaporation in long term operation of MCFCs can be accelerated at button cell level due to the increased rate of evaporation in the open-chamber configuration. This study is being carried out with several trials: the first trial aims to generate a benchmark of performance at button cell level, i.e. with accelerated electrolyte evaporation, at reference operating conditions, carrying out regular polarization curves and EIS until the performance degrades below a predefined level. The second trial aims to compensate the evaporation of electrolyte from the button cell by periodically adding carbonate and maintain a constant performance for the length of time that the first button cell (without carbonate addition) achieved. Once the isolated effect of electrolyte evaporation has been thus quantified, successive trials can be set up to superimpose other degradation and evaluate their interaction with the mechanism of electrolyte evaporation.

  • 289. Plazzotta, Beatrice
    et al.
    Dai, Jing
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Behrens, Manja A.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Pedersen, Jan Skov
    Core Freezing and Size Segregation in Surfactant Core-Shell Micelles2015In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 119, no 33, p. 10798-10806Article in journal (Refereed)
    Abstract [en]

    Nonionic surfactants containing poly(ethylene oxide) are chemically simple and biocompatible and form core-shell micelles at a wide range of conditions. For those reasons, they and their aggregates have been widely investigated. Recently, irregularities that were observed in the low-temperature behavior of surfactants of the kind [CH3(CH2)(n)O-(CH2CH2O)(m)H], (abbreviated CnEm) were assigned to a freezing-melting phase transition in the micellar core. In this work we expand the focus from the case of single component systems to binary surfactant systems at temperatures between 1 and 15 degrees C. By applying small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), and density measurements in pure C18E20 and C18E100 solutions and their mixtures, we show that core freezing/melting is also present in mixtures. Additionally, comparing SAXS data obtained from the mixture with those from the single components, it was possible to demonstrate that the phase transition leads to a reversible segregation of the surfactants from mixed micelles to distinct kinds of micelles of the two components.

  • 290. Plowright, Alleyn T.
    et al.
    Barton, Peter
    Bennett, Stuart
    Birch, Alan M.
    Birtles, Susan
    Buckett, Linda K.
    Butlin, Roger J.
    Davies, Robert D. M.
    Ertan, Anne
    Gutierrez, Pablo Morentin
    Kemmitt, Paul D.
    Leach, Andrew G.
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Turnbull, Andrew V.
    Waring, Michael J.
    Design and synthesis of a novel series of cyclohexyloxy-pyridyl derivatives as inhibitors of diacylglycerol acyl transferase 12013In: MedChemComm, ISSN 2040-2503, E-ISSN 2040-2511, Vol. 4, no 1, p. 151-158Article in journal (Refereed)
    Abstract [en]

    A novel series of potent diacylglycerol acyl transferase 1 inhibitors was developed from the clinical candidate AZD3988. Replacement of the phenyl cyclohexyl-ethanoate side chain with substituted oxy-linked side chains to introduce changes in shape and polarity, reduce lipophilicity and mask the hydrogen bond donors with internal hydrogen bond acceptors led to improvements in solubility, unbound clearance and excellent selectivity over the related enzyme acyl-coenzyme A:cholesterol acyltransferase 1. A comparison of the small molecule crystal structures of compound 4 and compound 28 is described. Compounds in this series have good ADMET properties and provide an exposure-dependent decrease in circulating plasma triglyceride levels in a rat oral lipid tolerance test.

  • 291.
    Pourmand, Payam
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    NMR detection of liquid dynamics in porous matrices2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Porous materials or a porous media can be encountered in our everyday life, both in industrial and household systems and in the nature. Generally speaking all solid and semisolid materials are porous to some degree e.g. different dense rock types, plastics etc. Porous materials are constantly finding more and more applications, both in industry and research. Many commercially important process in the industry utilize porous media e.g. flow of fluids through porous media for separation process and porous catalyst supports. This has strongly contributed to the development of porous media with controlled properties, which can be utilized for understanding the behavior of liquids confined in the material, and the morphology of these synthetic materials.This thesis work brings some insight and understanding of porous materials i.e. Controlled Pore Glass (CPG). Report also contains a brief explanation of Nuclear Magnetic Resonance (NMR) spectroscopy, diffusion NMR and other techniques such as Mercury porosimetry.The first part of the thesis is focused on determining the required amount of liquid i.e. octanol needed to achieve full pore saturation for different CPGs with varying pore sizes. This was achieved by taking into account that the transverse relaxation time T2 is sensitive in the ms-ns of motional correlation times, and that there are physical factors in porous material which affect the T2. Second part, diffusion NMR is used to study self-diffusion of octanol confined in CPG, thus bringing some insight on mass transfer limitations within porous systems. The report present results obtained from experiments with NMR and Diffusion NMR, discusses the issues that can arise when investigating porous materials and suggest solutions.

  • 292.
    Pourmand, Payam
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hedenqvist, Lisa
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pourrahimi, Amir Masoud
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Reitberger, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gedde, Ulf
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Effect of gamma radiation on carbon-black-filled EPDM seals in water and air2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 146, p. 184-191Article in journal (Refereed)
    Abstract [en]

    The effects of gamma radiation in air and water on a highly filled carbon-black-containing EPDM seal, used in transportation valves for old-fuel rods, were investigated. Samples were irradiated at a dose rate of 7 kGy h(-1) until total doses of 0.35, 1.4, 2.1 and 3.5 MGy were reached. The doses were chosen to correspond to 1, 4, 6 and 10 years of service. Infrared spectroscopy, mechanical indenter and NMR relaxation time (T-2) measurements indicated an oxidative crosslinking of the seal, which increased monotonically with the dose. The effects were larger in air than in water, and in air, diffusion-limited oxidation was observed. The compression set increased with increasing dose of radiation and was the highest for seals irradiated in air. The water uptake into the rubber, which was always lower than 1 wt.%, increased with the dose, showing the effect of increased polarity by the oxidation of the rubber.

  • 293.
    Pourmand, Payam
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Lisa
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Pourrahimi, Amir Massoud
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Furó, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Reitberger, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Effect of radiation on carbon-black-filled EPDM seals in water and air2017Manuscript (preprint) (Other academic)
    Abstract [en]

    The effects of γ-radiation in air and water on a highly filled carbon-black-containing EPDM seal, used in transportation valves for old-fuel rods, were investigated. Samples were irradiated at a dose rate of 7 kGy/h until total doses of 0.35, 1.4, 2.1 and 3.5 MGy were reached. The doses were chosen to correspond to 1, 4, 6 and 10 years in service. Infrared spectroscopy, mechanical indenter and NMR relaxation time (T2) measurements indicated an oxidative crosslinking of the seal, which increased monotonically with the dose. The effects were larger in air than in water, and in air, diffusion-limited oxidation was observed. The compression set increased with increasing doses of radiation and was the highest for seals irradiated in air. The water uptake into the rubber, which was always lower than 1 wt%, increased with the dose, showing the effects of increased polarity/oxidation of the rubber.

  • 294.
    Pourmand, Payam
    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, Polymeric Materials.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Radiochemical ageing of highly filled EPDM seals as revealed by accelerated ageing and ageing in-service for 21 years2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 144, p. 473-484Article in journal (Refereed)
    Abstract [en]

    Highly filled EPDM rubber used in cable transit seals in nuclear power plants were exposed to gamma radiation at a high dose rate at 23 degrees C in media with different oxygen partial pressures (1-21.2 kPa). The motivation of this study was threefold: highly filled polymers are replacing halogen-containing polymers and these materials have rendered less attention in the literature; there is a need to find efficient tools to make possible condition monitoring and extrapolation. Several profiling methods were used: IR microscopy, micro-indentation, micro-sample extraction/gravimetry and non-invasive NMR spectroscopy, and three different deterioration processes were identified: polymer oxidation, migration of low molar mass species, and anaerobic changes in the polymer network. IR microscopy, micro-indentation profiling and the portable NMR method confirmed diffusion-limited oxidation in samples irradiated in air. The inner non-oxidized part of the blocks showed a pronounced change in the indenter modulus by migration of primarily glyceryl tristearate migration was accelerated by the presence of oxygen in the surface layer and anaerobic changes in the polymer network. For extrapolation or for condition monitoring, it is best to use the data obtained by indenter modulus profiling and to use the correlation between indenter modulus and strain-at-break to quantify the sample status. Non-invasive NMR profiling provided useful data but was less precise than the indenter modulus data to predict the strain-at-break.

  • 295.
    Pourmand, Payam
    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, Polymeric Materials.
    Furó, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Gedde, Ulf W
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Deterioration of highly filled EPDM rubber exposed to thermal ageing in air: kinetics and non-destructive monitoringManuscript (preprint) (Other academic)
    Abstract [en]

    The effects of thermal ageing on EPDM cable transit seals were investigated. Samples were aged in air at 110, 120, 150 and 170 °C, and evaluated with tensile testing, indenter modulus profiling, oxidation profiling (using IR spectroscopy), nuclear magnetic resonance (NMR) spectroscopy profiling. The ageing resulted in an increase in the indenter modulus, the degree of oxidation and in a decrease in the NMR transverse relaxation time, T2. Diffusion-limited oxidation (DLO) occurred with a large oxidation gradient close to the sample surface. The portable NMR MOUSE (non-invasive method) was used to obtain detailed degradation profiles, up to a depth of 5 mm of the aged samples. The results indicated a deterioration process that was attributed to several mechanisms, i.e. oxidation, anaerobic crosslinking and migration of oil extender. By combining the data acquired from the profiling, separation and quantification of these three contributing mechanisms was determined. Additionally, it was shown that the portable NMR data correlated well with the strain at break data, highlighting the potential use of the portable NMR for condition monitoring.

  • 296.
    Pourmand, Payam
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Linde, Erik
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hedenqvist, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Dvinskikh, Sergey
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Gedde, U. W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Profiling of thermally aged EPDM seals using portable NMR, indenter measurements and IR spectroscopy facilitating separation of different deterioration mechanisms2016In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 53, p. 77-84Article in journal (Refereed)
    Abstract [en]

    The changes occurring in EPDM cable transit seals during thermal ageing and the causes of these changes were investigated. Samples were aged at a temperature of 170 °C, and subsequently evaluated with respect to the distance from the surface with modulus profiling, infrared (IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy, based on the extractable mass fraction profiles for initial and aged materials. The ageing resulted in an increase in the modulus and in the degree of oxidation and in a decrease in the NMR transverse relaxation time, T2. The NMR data were obtained in a non-invasive manner by ex situ experiments performed with a portable low-field spectrometer (NMR MOUSE). The results showed deterioration processes that can be attributed to different mechanisms i.e. oxidation, anaerobic crosslinking and migration of oil extender. The unique combination of parameter profiles made it possible to resolve and quantify these three contributing mechanisms. The NMR results highlight the potential of this method for on-site testing.

  • 297.
    Pradhan, Sulena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hedberg, Jonas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Tech Res Inst, Sweden.
    Wold, Susanna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Effect of sonication on particle dispersion, administered dose and metal release of non-functionalized, non-inert metal nanoparticles2016In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 18, no 9, article id 285Article in journal (Refereed)
    Abstract [en]

    In this study, we elucidate the effect of different sonication techniques to efficiently prepare particle dispersions from selected non-functionalized NPs (Cu, Al, Mn, ZnO), and corresponding consequences on the particle dose, surface charge and release of metals. Probe sonication was shown to be the preferred method for dispersing non-inert, non-functionalized metal NPs (Cu, Mn, Al). However, rapid sedimentation during sonication resulted in differences between the real and the administered doses in the order of 30-80 % when sonicating in 1 and 2.56 g/L NP stock solutions. After sonication, extensive agglomeration of the metal NPs resulted in rapid sedimentation of all particles. DLVO calculations supported these findings, showing the strong van der Waals forces of the metal NPs to result in significant NP agglomeration. Metal release from the metal NPs was slightly increased by increased sonication. The addition of a stabilizing agent (bovine serum albumin) had an accelerating effect on the release of metals in sonicated solutions. For Cu and Mn NPs, the extent of particle dissolution increased from <1.6 to similar to 5 % after sonication for 15 min. A prolonged sonication time (3-15 min) had negligible effects on the zeta potential of the studied NPs. In all, it is shown that it is of utmost importance to carefully investigate how sonication influences the physicochemical properties of dispersed metal NPs. This should be considered in nanotoxicology investigations of metal NPs.

  • 298.
    Prakobna, Kasinee
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Terenzi, Camilla
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Centres, Industrial NMR Centre.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Core-shell cellulose nanofibers for biocomposites: Nanostructural effects in hydrated state2015In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 125, p. 92-102Article in journal (Refereed)
    Abstract [en]

    Core-shell wood cellulose nanofibers (CNF) coated by an XG hemicellulose polymer are prepared and used to make biocomposites. CNF/XG biocomposites have interest as packaging materials and as hydrated CNF/XG plant cell wall analogues. Structure and properties are compared between Core-shell CNF/XG and more inhomogeneous CNF/XG. Experiments include XG sorption, dynamic light scattering of CNF nanoparticle suspensions, FE-SEM of nanostructure, moisture sorption, tensile testing in moist conditions and dynamic mechanical analysis. (2)H NMR relaxometry is performed on materials containing sorbed (2)H2O2 in order to assess water molecular dynamics in different materials. The results clarify the roles of CNF, XG and the CNF/XG interface in the biocomposites, both in terms of moisture sorption mechanisms and mechanical properties in moist state. The concept of core-shell nanofiber network biocomposites, prepared by filtering of colloids, provides improved control of polymer matrix distribution and interface structure. Also, present mechanical properties are much superior to comparable plant fiber biocomposites.

  • 299. Rahm, M.
    et al.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Green Propellants Based on Dinitramide Salts: Mastering Stability and Chemical Compatibility Issues2014In: Green Energetic Materials, Wiley-Blackwell, 2014, p. 179-204Chapter in book (Other academic)
    Abstract [en]

    Mastery of dinitramide salts requires the intertwined use of compatibility testing, surface sensitive spectroscopy, and quantum chemical calculations. This chapter shows these combined approaches providing atomistic and fundamental understanding of the complex processes that govern the decomposition, reactivity, and in the end, usefulness of dinitramide-based materials. Polarized dinitramide anions residing on the surface of dinitramide salts are theoretically predicted to exist and to dramatically accelerate decomposition. Such structures have been observed on the outmost monolayers of ammonium dinitramide (ADN) crystals using surface sensitive vibrational spectroscopy. Stabilization of ADN is realized by hindering the polarization of such structures with surface-active stabilizing agents. The full mechanisms for the self-decomposition of solid-state ADN and potassium dinitramide (KDN) are presented. Radical decomposition intermediates stress the necessity of using anti-oxidants as stabilizers. The anomalous solid-state behavior that has been observed in several dinitramide salts is also discussed and explained. Finally, the use of the dinitramide moiety in synthesis is briefly reviewed, and several mechanisms for its reactions with various olefinic double bonds are discussed.

  • 300.
    Razdan, Mayuri
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Trummer, Martin
    Zagidulin, Dmitrij
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Shoesmith, David W.
    Electrochemical and Surface Characterization of Uranium Dioxide Containing Rare-Earth Oxide (Y2O3) and Metal (Pd) Particles2014In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 130, p. 29-39Article in journal (Refereed)
    Abstract [en]

    Four specimens of uranium dioxide doped with rare-earth oxide (Y2O3) and/or metal particles (Pd) i.e., UO2, UO2-Y2O3, UO2-Y2O3-Pd, UO2-Pd were surface and electrochemically characterized using scanning electron microscopy (SEM/EDX), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry. Surface analyses showed that the dopants are present as a separate phase in the UO2 matrix and all oxides are non-stoichiometric and contain a large number of defect clusters. Voltammetry shows anodic oxidation begins at sub-thermodynamic potentials and the presence of multiple cathodic reduction peaks indicates the presence of a number of structural domains with different electrochemical reactivities. Corrosion potential (E-CORR) and polarization resistance measurements (Rp) in the presence of H2O2 suggests that the anodic reactivity of all the specimens is comparable and high compared to 1.5 at% SIMFUEL. The lower Rp values obtained on the doped specimens is consistent with the presence of readily oxidizable cuboctahedral clusters in the oxide matrix.

345678 251 - 300 of 392
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