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  • 151. Bernard-Granger, Guillaume
    et al.
    Benameur, Nassira
    Addad, Ahmed
    Nygren, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Guizard, Christian
    Deville, Sylvain
    Phenomenological analysis of densification mechanism during spark plasma sintering of MgAl2O42009In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 24, no 6, p. 2011-2020Article in journal (Refereed)
    Abstract [en]

    Spark plasma sintering (SPS) of MgAl2O4 powder was investigated at temperatures between 1200 and 1300 degrees C. A significant grain growth was observed during densification. The densification rate always exhibits at least one strong minimum, and resumes after an incubation period. Transmission electron microscopy investigations performed on sintered samples never revealed extensive dislocation activity in the elemental grains. The densification mechanism involved during SPS was determined by anisothermal (investigation of the heating stage of a SPS run) and isothermal methods (investigation at given soak temperatures). Grain-boundary sliding, accommodated by an in-series {interface-reaction/lattice diffusion of the O-2(-) anions} mechanism controlled by the interface-reaction step, governs densification. The zero-densification-rate period, detected for all soak temperatures, arise from the difficulty of annealing vacancies, necessary for the densification to proceed. The detection of atomic ledges at grain boundaries and the modification of the stoichiometry of spinel during SPS could be related to the difficulty to anneal vacancies at temperature soaks.

  • 152.
    Bernin, Diana
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). University of Gothenburg, Sweden.
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Perspectives on NMR studies of CO2 adsorption2018In: Current Opinion in Colloid & Interface Science, ISSN 1359-0294, E-ISSN 1879-0399, Vol. 33, p. 53-62Article, review/survey (Refereed)
    Abstract [en]

    There is a consensus about a long-term goal of a carbon-neutral energy cycle, but the CO2 emissions to the atmosphere are currently very large. Carbon Capture and Storage (CCS) technologies could allow a transformation of the global energy system into a carbon-neutral one and simultaneously keeping the temperature rises within agreed bounds. The CO2 separation step of CCS is, however, very expensive, and adsorption-driven technologies have been put forward as alternatives. Hence, a recent focus has been on studying solid adsorbents for CO2, which include activated carbons, zeolites, metal-organic frameworks, and amine-modified silica. In this context, we summarize the literature concerning CO2 sorption studied with Nuclear Magnetic Resonance (NMR), outline selected NMR methods, and present an outlook for further studies.

  • 153. Bhatt, Aarti Sripathi
    et al.
    Bhat, Denthaje Krishna
    Santosh, Mysore Sridhar
    Tai, Cheuk-wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Chitosan/NiO nanocomposites: a potential new dielectric material2011In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 21, no 35, p. 13490-13497Article in journal (Refereed)
    Abstract [en]

    The study of electrochemical behavior of organic-inorganic nanocomposite materials remains a major challenge for application in energy storage devices. Here, new composite materials of chitosan and NiO nanoparticles have been fabricated. The NiO nanoparticles are well characterized by infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The electrical properties of the films are studied by impedance spectroscopy at different temperatures; and thereby permittivity, electric modulus and conductivity data are obtained. By studying the variations in permittivity and electric modulus spectra with respect to applied frequency signal and temperature, the ionic conductivity of the material is investigated. The Correlated Barrier Hopping model is employed to understand the conduction mechanism. An admirable conductivity of 1.4 x 10(-2) S cm(-1) is obtained for a nanocomposite with 4 wt% NiO content. The activation energies of the composite films decrease with increase in NiO content, from 16.5 to 4.8 kJ mol(-1).

  • 154. Biendicho, Jordi Jacas
    et al.
    Noréus, Dag
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Offer, Colin
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Smith, Ronald I.
    Hull, Stephen
    New Opportunities for Air Cathode Batteries; in-Situ Neutron Diffraction Measurements2018In: Frontiers in energy research, ISSN 2296-598X, Vol. 6, article id UNSP 69Article in journal (Refereed)
    Abstract [en]

    Batteries with air electrodes are gaining interest as Energy Storage Systems (ESSs) for Electrical Vehicles (EVs) because of their high specific energy density. The electrochemical performance of these batteries is limited by the metallic electrode, which suffers structural transformations and corrosion during cycling that reduces the cycle life of the battery. In this context, relevant information on the discharge products may be obtained by in-situ neutron diffraction, a suitable technique to study electrodes that contain light elements or near neighbor elements in the periodic table. Case studies of MH-air and Fe-air batteries are highlighted.

  • 155.
    Biendicho, Jordi Jacas
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). STFC Rutherford Appleton Laboratory, England.
    Roberts, Matthew
    Noréus, Dag
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lagerqvist, Ulrika
    Smith, Ronald I.
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Norberg, Stefan T.
    Eriksson, Sten G.
    Hull, Stephen
    In situ investigation of commercial Ni(OH)(2) and LaNi5-based electrodes by neutron powder diffraction2015In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 30, no 3, p. 407-416Article in journal (Refereed)
    Abstract [en]

    Electrochemical reactions at both positive and negative electrodes in a nickel metal hydride (Ni-MH) battery during charge have been investigated by in situ neutron powder diffraction. Commercially available beta-Ni(OH)(2) and LaNi5-based powders were used in this experiment as positive and negative electrodes, respectively. Exchange of hydrogen by deuterium for the beta-Ni(OH)(2) electrode was achieved by ex situ cycling of the cell prior to in situ measurements. Neutron diffraction data collected in situ show that the largest amount of deuterium contained at the positive electrode is de-intercalated from the electrode with no phase transformation involved up to similar to 100 mA h/g and, in addition, the 110 peak width for the positive electrode increases on charge. The negative electrode of composition MmNi(3.6)Al(0.4)Mn(0.3)Co(0.7), where Mm = Mischmetal, exhibits a phase transformation to an intermediate hydride gamma phase first and then to the beta phase on charge. Unit cell dimensions and phase fractions have been investigated by Rietveld refinement of the crystal structure.

  • 156.
    Biendicho, Jordi Jacas
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). STFC Rutherford Appleton Laboratory, England.
    Roberts, Matthew
    Offer, Colin
    Noréus, Dag
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Widenkvist, Erika
    Smith, Ronald I.
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Edström, Kristina
    Norberg, Stefan T.
    Eriksson, Sten G.
    Hull, Stephen
    New in-situ neutron diffraction cell for electrode materials2014In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 248, p. 900-904Article in journal (Refereed)
    Abstract [en]

    A novel neutron diffraction cell has been constructed to allow in-situ studies of the structural changes in materials of relevance to battery applications during charge/discharge cycling. The new design is based on the coin cell geometry, but has larger dimensions compared to typical commercial batteries in order to maximize the amount of electrode material and thus, collect diffraction data of good statistical quality within the shortest possible time. An important aspect of the design is its modular nature, allowing flexibility in both the materials studied and the battery configuration. This paper reports electrochemical tests using a Nickel-metal-hydride battery (Ni-MH), which show that the cell is able to deliver 90% of its theoretical capacity when using deuterated components. Neutron diffraction studies performed on the Polaris diffractometer using nickel metal and a hydrogen-absorbing alloy (MH) clearly show observable changes in the neutron diffraction patterns as a function of the discharge state. Due to the high quality of the diffraction patterns collected in-situ (i.e. good peak-to-background ratio), phase analysis and peak indexing can be performed successfully using data collected in around 30 min. In addition to this, structural parameters for the beta-phase (charged) MH electrode obtained by Rietveld refinement are presented.

  • 157.
    Biendicho, Jordi Jacas
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). STFC Rutherford Appleton Laboratory, England.
    Shafeie, Samrand
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Frenck, Louise
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Pierre & Marie Curie University, France.
    Gavrilova, Daria
    Böhme, Solveigh
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Chemnitz University of Technology, Germany.
    Bettanini, A. M.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Universita Ca Foscari Venezia, Italy.
    Svedlindh, Peter
    Hull, Steve
    Zhe, Zhao
    Istomin, S. Y.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Synthesis and characterisation of perovskite SrxY1-xFeO3-d (=.63≤x<1) and Sr0.75Y0.25Fe1-yMyO3-d (M=Cr, Mn, Ni) (y= 0.2, 0.33, 0.5)2013In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 200, p. 30-38Article in journal (Refereed)
    Abstract [en]

    Oxygen-deficient ferrates with the cubic perovskite structure SrxY1-xFeO3-d were prepared in air (0.71 ≤ x ≤ 0.91) as well as in N2 (x=0.75 and 0.79) at 1573K. The oxygen content of the compounds prepared in air increases with increasing strontium content from 3-δ=2.79(2) for x=0.75 to 3-δ=2.83(2) for x=0.91. Refinement of the crystal structure of Sr0.75Y0.25FeO2.79 using TOF neutron powder diffraction (NPD) data shows high anisotropic atomic displacement parameter (ADP) for the oxygen atom resulting from a substantial cation and anion disorder. Electron diffraction (ED) and high-resolution electron microscopy (HREM) studies of Sr0.75Y0.25FeO2.79 reveal a modulation along <100>p with G± ~0.4<100>p indicating a local ordering of oxygen vacancies. Magnetic susceptibility measurements at 5-390K show spin-glass behaviour with dominating antiferromagnetic coupling between the magnetic moments of Fe cations. Among the studied compositions, Sr0.75Y0.25FeO2.79 shows the lowest thermal expansion coefficient (TEC) of 10.5 ppm K-1 in air at 298-673K. At 773-1173K TEC increases up to 17.2 ppm K-1 due to substantial reduction of oxygen content. The latter also results in a dramatic decrease of the electrical conductivity in air above 673K. Partial substitution of Fe by Cr, Mn and Ni according to the formula Sr0.75Y0.25Fe1-yMyO3-δ (y=0.2, 0.33, 0.5) leads to cubic perovskites for all substituents with y=0.2. Their TECs are higher in comparison with un-doped Sr0.75Y0.25FeO2.79. Only M=Ni has increased electrical conductivity compared to un-doped Sr0.75Y0.25FeO2.79.

  • 158. Binbin, Song
    et al.
    Peizhong, Feng
    Jianzhong, Wang
    Yuan, Ge
    Guangzhi, Wu
    Xiaohong, Wang
    Farid, Akhtar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden.
    Oxidation properties of self-propagating high temperature synthesized niobium disilicide2014In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 85, p. 311-317Article in journal (Refereed)
    Abstract [en]

    NbSi2 monoliths were prepared by self-propagating high temperature synthesis (SHS) and hot pressing (HP) and their oxidation behavior was investigated at various temperatures (823-1123 K) in air. The combustion mode of SHS reaction was steady state combustion, and the combustion product was single-phase NbSi2. Oxidation studies show that the highest mass gain was 0.95675 kg m(-2) at 1023 K. In cyclic oxidation, the oxidation rate was reduced and the mass gain was only 0.15507 kg m(-2). A dense protective amorphous SiO2 scale formed at 823 K and 923 K whereas a porous multilayer SiO2 and alpha/beta-Nb2O5 oxide scales formed at and above 1023 K and spalled off. Pest oxidation of NbSi2 monoliths was not observed in hot pressed NbSi2 monoliths.

  • 159. Birnbaum, Linda S.
    et al.
    Bergman, Åke
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    Brominated and Chlorinated Flame Retardants: The San Antonio Statement2010In: Journal of Environmental Health Perspectives, ISSN 0091-6765, E-ISSN 1552-9924, Vol. 118, no 12, p. A516-A518Article in journal (Refereed)
    Abstract [en]

    The San Antonio Statement on Brominated and Chlorinated Flame Retardants addresses the growing concern in the scientific community about the persistent, bioaccumulative, and toxic properties of brominated and chlorinated organic flame retardants (BFRs and CFRs, respectively) and the exposure to humans and wildlife as a result of intensive use. Nearly 150 scientists from 22 countries have signed the statement since it was presented at the 30th International Symposium on Halogenated Persistent Organic Pollutants (Dioxin 2010), held 1217 September 2010 in San Antonio, Texas. The scientist signatories are experts on the health effects and environmental fate of BFRs and CFRs and environmental contaminants in general. The International Panel on Chemical Pollution (IPCP), an international network of scientists working on various aspects of chemical pollution, also has approved the statement.

  • 160. Björk, Christel
    et al.
    Nenonen, Hannah
    Giwercman, Aleksander
    Bergman, Åke
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    Rylander, Lars
    Giwercman, Yvonne Lundberg
    Persistent organic pollutants have dose and CAG repeat length dependent effects on androgen receptor activity in vitro2011In: Reproductive Toxicology, ISSN 0890-6238, E-ISSN 1873-1708, Vol. 32, p. 293-297Article in journal (Refereed)
    Abstract [en]

    Recently, the effect of exposure to persistent organic pollutants (POPS) on sperm concentration was only seen in men with a short androgen receptor (AR) gene CAG repeat. In order to investigate whether these effects could be observed also in vitro, we tested the impact of 2,2’,4,4’,5,5’-hexachlorobiphenyl (CB-153) and 1,1-bis-(4-chlorophenyl)-2,2-dichloroethene (4,4’-DDE) on 5 alpha-dihydrotestosterone activated ARs containing 16,22 and 28 CAG repeats, respectively. Single exposure to 4,4’-DDE had the most pronounced effect on the AR activity containing 16 CAG repeats, whereas 28 CAG was the most sensitive variant when a mixture of the two compounds was added. Thus, our in vitro results have confirmed the in vivo data indicating a CAG repeat length dependent effect of endocrine disrupters on the AR activity.

  • 161.
    Björnerbäck, Fredrik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sustainable porous organic materials: Synthesis, sorption properties and characterization2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The resources available to us humans, including metals, minerals, biomass, air, water, and anything else on the planet, are being used at an increasing rate. This anthropogenic use of resources both depletes the resources and has negative impacts on other resources, e.g. the biosphere. Thus, developing (more) sustainable chemical and industrial processes are of the utmost importance for the well-being of the creatures of Earth and for the long-term sustainability of human society.

    This thesis focuses on organic porous materials, and more specifically their synthesis and characterization. Porous materials are, for example, used in detergents, water treatment, bio gas upgrading, carbon dioxide capture, as catalysts, in sensors, and in various biological applications. The application of porous materials can contribute to the drive towards a more sustainable society. However, porous materials are typically not sustainable themselves. Thus, there is a need to develop more sustainable porous materials. The synthesis and characterization of three different groups of porous organic materials are described in this thesis.

    In pulp- and paper manufacturing, lignin is separated from desirable products and is typically combusted for heat. In one section of this thesis, lignin was used to produce bio-oil for potential use in fuels and chemicals. However, the bio-oil process produced a solid by-product. The by-product was used to synthesize and study activated carbons with very high porosities and magnetic properties, a combination of properties that may prove to be useful in applications.

    Sugar is known to produce solid and unwanted compounds through reactions with acids. It is shown here that it is possible to produce highly microporous humins, i.e. organic porous materials with a large amount of small pores, using sulphuric acid and a range of saccharides and bio-based polymers. This work supports that solid by-products in a wide range of biomass conversion processes can be of high value, both economically and as replacements for less sustainable alternatives.

    The biosphere contains vast amounts of molecules with aromatic structures. The last section of this thesis shows how such aromatic molecules can be used to produce highly porous materials through Friedel-Crafts type chemistry using sulfolane as a solvent and iron chloride as a catalyst. This synthesis strategy produces high-performance materials, improves upon the sustainability of traditional Friedel-Crafts chemistry, and makes use of typically underutilized and abundant bio-based molecules.

  • 162.
    Björnerbäck, Fredrik
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bernin, Diana
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Chalmers University of Technology, Sweden.
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Microporous Humins Synthesized in Concentrated Sulfuric Acid Using 5-Hydroxymethyl Furfural2018In: ACS omega, ISSN 2470-1343, Vol. 3, no 8, p. 8537-8545Article in journal (Refereed)
    Abstract [en]

    A new class of highly porous organic sorbents called microporous humins is presented. These microporous humins are derived from sustainable and industrially abundant resources, have high heat of CO2 sorption, and could potentially be useful for the separation of carbon dioxide from gas mixtures. Their synthesis involves the polymerization of 5-hydroxymethyl furfural (HMF) in concentrated sulfuric acid and treatment with diethyl ether and heat. In particular, the porosities were tuned by the heat treatment. HMF is a potential platform chemical from biorefineries and a common intermediate in carbohydrate chemistry. A high uptake of CO2 (up to 5.27 mmol/g at 0 degrees C and 1 bar) and high CO2-over-N-2 and CO2-over-CH4 selectivities were observed. The microporous humins were aromatic and structurally amorphous, which was shown in a multipronged approach using C-13 nuclear magnetic resonance and Fourier transform infrared spectroscopies, elemental analysis, and wide-angle X-ray scattering.

  • 163.
    Björnerbäck, Fredrik
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Highly Porous Hypercrosslinked Polymers Derived from Biobased Molecules2019In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 12, no 4, p. 839-847Article in journal (Refereed)
    Abstract [en]

    Highly porous and hyper-cross-linked polymers (HCPs) have a range of applications and are typically synthesized in an unsustainable manner. Herein, HCPs were synthesized from abundant biobased or biorelated compounds in sulfolane with iron(III) chloride as Lewis acid catalyst. As reactants, quercetin, tannic acid, phenol, 1,4-dimethoxybenzene, glucose, and a commercial bark extract were used. The HCPs had high CO2 uptake (up to 3.94 mmol g(-1) at 0 degrees C and 1 bar), total pore volumes (up to 1.86 cm(3) g(-1)), and specific surface areas (up to 1440 m(2) g(-1)). H-1 NMR, C-13 NMR, and IR spectroscopy, wide-angle X-ray scattering, elemental analysis, and SEM revealed, for example, that the HCPs consisted of amorphous and cross-linked aromatic and phenolic structures with significant contents of aliphatics, oxygen, and sulfur.

  • 164.
    Björnerbäck, Fredrik
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Microporous Humins Prepared from Sugars and Bio-Based Polymers in Concentrated Sulfuric Acid2019In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 7, no 1, p. 1018-1027Article in journal (Refereed)
    Abstract [en]

    Highly microporous humins were synthesized from readily available sugars and bio-based polymers (monosaccharides, disaccharides, and polysaccharides) in sulfuric acid followed by a diethyl ether wash and heat treatment at 400 degrees C. The relative sustainability, costs of production, and availability of the starting materials were improved significantly as compared with the 5-hydroxymethyl-furfural-based microporous humins recently studied by us. A multipronged approach was used to study the detailed characteristics of the adsorbents. Results from H-1 NMR, C-13 NMR, FTIR, WAXS, and elemental analysis were combined and showed that the adsorbents predominantly consisted of amorphous and aromatic carbon structures being rich in oxygen. They were highly porous, and the micropore volumes varied among the compositions as could be observed by analyzing CO2 and N-2 gas adsorption data. Comparably high CO2 uptakes of 4.25 and 1.94 mmol/g at 0 degrees C and 1 and 0.15 bar were observed. With the synthesis of microporous humins with varying porosities, the domain of potential applications of this class of materials could be expanded.

  • 165. Björnetun Haugen, Astri
    et al.
    Morozov, Maxim I.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Grande, Tor
    Einarsrud, Mari-Ann
    Effect of crystallographic orientation in textured Ba0.92Ca0.08TiO3 piezoelectric ceramics2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 116, no 13, p. 134102-Article in journal (Refereed)
    Abstract [en]

    Strongly textured lead-free Ba0.92Ca0.08TiO3 piezoelectric ceramics were fabricated by tape casting and templated grain growth. Dense ceramics with both favorable < 100 > and unfavorable < 111 > texture were successfully prepared. Enhanced piezoelectric performance was demonstrated for ceramics with < 100 > texture, in line with the predictions based on reported piezoelectric coefficients of tetragonal BaTiO3. Due to the expanded tetragonal range through Ca-substitution, < 100 > texture is favorable over a wide temperature range. The < 100 > texture also results in the enhanced piezoelectric performance being temperature-independent. In addition to engineering of stable, high-performance lead-free piezoelectric ceramics, this study has demonstrated that consideration of the extender/rotator nature of piezoelectric properties is imperative for improving the piezoelectric response through texturing.

  • 166. Blanchart, P.
    et al.
    Dembele, A.
    Dembele, C.
    Plea, M.
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Granet, R.
    Sol, V.
    Gloaguen, V.
    Degot, M.
    Krausz, P.
    Mechanism of traditional Bogolan dyeing technique with clay on cotton fabric2010In: Applied Clay Science, ISSN 0169-1317, E-ISSN 1872-9053, Vol. 50, no 4, p. 455-460Article in journal (Refereed)
    Abstract [en]

    Bogolan is a traditional dyeing technique deeply rooted in Mali It uses local clays from Niger River region and a leave extract from N galama trees (Anogeissus leiocarpa) The clay contains a significant amount of iron (hydr)oxides mainly akaganeite It reacts with N galama coating onto cotton to form black or brown colors UV/Vis and IR spectroscopy indicated very similar behavior of N galama leaves extract and carboxylic aromatic acids mainly ellagic or gallic acids which form dark colored complexes with iron Since iron (hydr) oxides are coated on clay mineral particles they contribute to the fixation of the Clay mineral particles and also cause the dark color X-ray diffraction of oriented tissue and SEM observations confirmed the presence of clay particles attached on the fiber surface.

  • 167.
    Bogdanska, Jasna
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Borg, Daniel
    Sundström, Maria
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    Bergström, Ulrika
    Halldin, Krister
    Abedi-Valugerdi, Manuchehr
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Bergman, Åke
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    Nelson, Buck
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    DePierre, Joseph
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Nobel, Stefan
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Tissue distribution of (35)S-labelled perfluorooctane sulfonate in adult mice after oral exposure to a low environmentally relevant dose or a high experimental dose2011In: Toxicology, ISSN 0300-483X, E-ISSN 1879-3185, Vol. 284, no 1-3, p. 54-62Article in journal (Refereed)
    Abstract [en]

    The widespread environmental pollutant perfluorooctane sulfonate (PFOS), detected in most animal species including the general human population, exerts several effects on experimental animals, e.g., hepatotoxicity, immunotoxicity and developmental toxicity. However, detailed information on the tissue distribution of PFOS in mammals is scarce and, in particular, the lack of available information regarding environmentally relevant exposure levels limits our understanding of how mammals (including humans) may be affected. Accordingly, we characterized the tissue distribution of this compound in mice, an important experimental animal for studying PFOS toxicity. Following dietary exposure of adult male C57/BL6 mice for 1-5 days to an environmentally relevant (0.031 mg/kg/day) or a 750-fold higher experimentally relevant dose (23 mg/kg/day) of (35)S-PFOS, most of the radioactivity administered was recovered in liver, bone (bone marrow), blood, skin and muscle, with the highest levels detected in liver, lung, blood, kidney and bone (bone marrow). Following high daily dose exposure, PFOS exhibited a different distribution profile than with low daily dose exposure, which indicated a shift in distribution from the blood to the tissues with increasing dose. Both scintillation counting (with correction for the blood present in the tissues) and whole-body autoradiography revealed the presence of PFOS in all 19 tissues examined, with identification of thymus as a novel site for localization for PFOS and bone (bone marrow), skin and muscle as significant body compartments for PFOS. These findings demonstrate that PFOS leaves the bloodstream and enters most tissues in a dose-dependent manner.

  • 168.
    Bogdanska, Jasna
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Sundström, Maria
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bergström, Ulrika
    Borg, Daniel
    Abedi-Valugerdi, Manuchehr
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Bergman, Åke
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    DePierre, Joseph
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Nobel, Stefan
    Tissue distribution of S-35-labelled perfluorobutanesulfonic acid in adult mice following dietary exposure for 1-5 days2014In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 98, p. 28-36Article in journal (Refereed)
    Abstract [en]

    Perfluorobutanesulfonyl fluoride (PBSF) has been introduced as a replacement for its eight-carbon homolog perfluorooctanesulfonyl fluoride (POSF) in the manufacturing of fluorochemicals. Fluorochemicals derived from PBSF may give rise to perfluorobutanesulfonic acid (PFBS) as a terminal degradation product. Although basic mammalian toxicokinetic data exist for PFBS, information on its tissue distribution has only been reported in one study focused on rat liver. Therefore, here we characterized the tissue distribution of PFBS in mice in the same manner as we earlier examined its eight-carbon homolog perfluorooctanesulfonate (PFOS) to allow direct comparisons. Following dietary exposure of adult male C57/BL6 mice for 1,3 or 5 d to 16 mg S-35-PFBS kg(-1) d(-1), both scintillation counting and whole-body autoradiography (WBA) revealed the presence of PFBS in all of the 20 different tissues examined, demonstrating its ability to leave the bloodstream and enter tissues. After 5 d of treatment the highest levels were detected in liver, gastrointestinal tract, blood, kidney, cartilage, whole bone, lungs and thyroid gland. WBA revealed relatively high levels of PFBS in male genital organs as well, with the exception of the testis. The tissue levels increased from 1 to 3 d of exposure but appeared thereafter to level-off in most cases. The estimated major body compartments were whole bone, liver, blood, skin and muscle. This exposure to PFBS resulted in 5-40-fold lower tissue levels than did similar exposure to PFOS, as well as in a different pattern of tissue distribution, including lower levels in liver and lungs relative to blood.

  • 169.
    Bogdanska, Jasna
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Sundström, Maria
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bergström, Ulrika
    Institutionen för miljötoxikologi, Uppsala universitet.
    Borg, Daniel
    Institutet för miljömedicin, Karolinska institutet.
    Abedi-Valugerdi, Mauchehr
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Bergman, Åke
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nelson, Buck
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    DePierre, Joseph
    Institutionen för biokemi och biofysik, Department of Biochemistry and Biophysics.
    Nobel, Stefan
    Department of molecular medicin and surgery, Karolinska institutet.
    Tissue distribution of 35S-labelled perfluorobutane sulfonic acid in adult mice following dietary exposure for 1-5 daysManuscript (preprint) (Other academic)
  • 170.
    Bogár, Krisztián
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Krumlinde, Patrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bacsik, Zoltán
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Heterogenized Wilkinson's Catalyst for Transfer Hydrogenation of Carbonyl Compounds2011In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 23, p. 4409-4414Article in journal (Refereed)
    Abstract [en]

    Wilkinson’s catalyst [RhCl(PPh3)3] was heterogenized on common silica by the use of a grafting/anchoring technique. The immobilized catalyst showed high activity and selectivity in transfer hydrogenation reactions of a range of carbonyl compounds in 2-propanol. Reactions carried out in 2-propanol at reflux afforded the corresponding alcohols in high yields in short reaction times. The heterogeneous feature ofthe catalyst allows for easy recovery and efficient reuse in the same reaction up to 5 times without any detectible loss of catalytic activity.

  • 171. Boily, Jean-Francois
    et al.
    Yesilbas, Merve
    Uddin, Munshi Md. Musleh
    Lu, Baiqing
    Trushkina, Yulia
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Salazar-Alvarez, German
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Thin Water Films at Multifaceted Hematite Particle Surfaces2015In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, no 48, p. 13127-13137Article in journal (Refereed)
    Abstract [en]

    Mineral surfaces exposed to moist air stabilize nanometer- to micrometer-thick water films. This study resolves the nature of thin water film formation at multifaceted hematite (alpha-Fe2O3) nanoparticle surfaces with crystallographic faces resolved by selected area electron diffraction. Dynamic vapor adsorption (DVA) in the 0-19 Torr range at 298 K showed that these particles stabilize water films consisting of up to 4-5 monolayers. Modeling of these data predicts water loadings in terms of an adsorption regime (up to 16 H2O/nm(2)) involving direct water binding to hematite surface sites, and of a condensation regime (up to 34 H2O/nm(2)) involving water binding to hematite-bound water nanodusters. Vibration spectroscopy identified the predominant hematite surface hydroxo groups (-OH, mu-OH, mu(3)-OH) through which first layer water molecules formed hydrogen bonds, as well as surface iron sites directly coordinating water molecules (i.e., as geminal eta-(OH2)(2) sites). Chemometric analyses of the vibration spectra also revealed a strong correspondence in the response of hematite surface hydroxo groups to DVA-derived water loadings. These findings point to a near-saturation of the hydrogen-bonding environment of surface hydroxo groups at a partial water vapor pressure of similar to 8 Torr (similar to 40% relative humidity). Classical molecular dynamics (MD) resolved the interfacial water structures and hydrogen bonding populations at five representative crystallographic faces expressed in these nanoparticles. Simulations of single oriented slabs underscored the individual roles of all (hydro)oxo groups in donating and accepting hydrogen bonds with first layer water in the adsorption regime. These analyses pointed to the preponderance of hydrogen bond-donating -OH groups in the stabilization of thin water films. Contributions of mu-OH and mu(3)-OH groups are secondary, yet remain essential in the stabilization of thin water films. MD simulations also helped resolve crystallographic controls on water water interactions occurring in the condensation regime. Water water hydrogen bond populations are greatest on the (001) face, and decrease in importance in the order (001) > (012) approximate to (110) > (014) >> (100). Simulations of a single (similar to 5 nm x similar to 6 nm x similar to 6 nm) nanometric hematite particle terminated by the (001), (110), (012), and (100) faces also highlighted the key roles that sites at particle edges play in interconnecting thin water films grown along contiguous crystallographic faces. Hydroxo water hydrogen bond populations showed that edges were the preferential loci of binding. These simulations also suggested that equilibration times for water binding at edges were slower than on crystallographic faces. In this regard, edges, and by extension roughened surfaces, are expected to play commanding roles in the stabilization of thin water films. Thus, in focusing on the properties of nanometric-thick water layers at hematite surfaces, this study revealed the nature of interactions between water and multifaced particle surfaces. Our results pave the way for furthering our understanding of mineral-thin water film interfacial structure and reactivity on a broader range of materials.

  • 172. Bojarski, Stephanie A.
    et al.
    Stuer, Michael
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Swiss Federal Institute of Technology Lausanne, Switzerland .
    Zhao, Zhe
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bowen, Paul
    Rohrer, Gregory S.
    Influence of Y and La Additions on Grain Growth and the Grain-Boundary Character Distribution of Alumina2014In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 97, no 2, p. 622-630Article in journal (Refereed)
    Abstract [en]

    Grain-boundary character distributions (GBCDs) were determined for spark plasma sintered Y- and La-doped aluminas prepared at temperatures between 1450 degrees C and 1600 degrees C. La doping leads to grain boundaries that adopt (0001) orientations 3.7 times more frequently than expected in a random distribution, whereas the Y-doped microstructures are more equiaxed. At 1500 degrees C, some of the boundaries in the Y-doped samples transform to a higher mobility complexion; in this microstructure, the {01 (1) over bar2} grain-boundary plane is 1.3 times more likely to occur than expected in a random distribution. After the fast-growing grains impinge, the dominant plane becomes {11 (2) over bar0} and these boundaries have areas that are 1.2 times more likely to occur than expected in a random distribution. The grain-boundary planes in the Y- and La-codoped samples preferred (0001) and {01 (1) over bar2>} orientations, combining the characteristics of the singly doped samples. Grain boundaries with a 60 degrees misorientation about [0001] were up to six times more common than random in the Y-doped samples. The preference for (0001) oriented grain-boundary planes in the La-doped sample persisted at all specific misorientations.

  • 173. Bordoloi, Ankur
    et al.
    Sahoo, Suman
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Halligudi, S. B.
    Immobilized Molybdovanadophosphoric Acid for Selective Oxidations2013In: Catalysis surveys from Asia, ISSN 1571-1013, E-ISSN 1574-9266, Vol. 17, no 3-4, p. 132-146Article in journal (Refereed)
    Abstract [en]

    In this review, we have summarized our work on the immobilization of molybdovanadophosphoric acids onto mesoporous silica and mesoporous carbon by different approaches such as amine functionalization and ionic liquid functionalization. All catalyst materials were well characterized by various ex-situ and in situ techniques for their structural integrity and physico-chemical properties. These materials were tested in different selective oxidation processes to develop environmentally benign protocols for the synthesis of fine chemicals and tried to study their mechanisms.

  • 174. Borg, D.
    et al.
    Bogdanska, J.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Sundström, Maria
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    Nobel, S.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Håkansson, H.
    Bergman, Åke
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    DePierre, J. W.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Halldin, K.
    Bergstrom, U.
    Tissue distribution of S-35-labelled perfluorooctane sulfonate (PFOS) in C57Bl/6 mice following late gestational exposure2010In: Reproductive Toxicology, ISSN 0890-6238, E-ISSN 1873-1708, Vol. 30, no 4, p. 558-565Article in journal (Refereed)
    Abstract [en]

    Exposure of rodents in utero to perfluorooctane sulfonate (PFOS) impairs perinatal development and survival Following intravenous or gavage exposure of C57Bl/6 mouse dams on gestational day (GD) 16 to S-35-PFOS (12 5 mg/kg) we determined the distribution in dams fetuses (GD18 and GD20) and pups (postnatal day 1 PND1) employing whole-body autoradiography and liquid scintillation counting In dams levels were highest in liver and lungs After placental transfer S-35-PFOS was present on GD18 at 2-3 times higher levels in lungs liver and kidneys than in maternal blood In PND1 pups levels in lungs were significantly higher than in GD18 fetuses A heterogeneous distribution of S-35-PFOS was observed in brains of fetuses and pups with levels higher than in maternal brain This first demonstration of substantial localization of PFOS to both perinatal and adult lungs is consistent with evidence describing the lung as a target for the toxicity of PFOS at these ages.

  • 175. Botan, Alexandru
    et al.
    Favela-Rosales, Fernando
    Fuchs, Patrick F. J.
    Javanainen, Matti
    Kanduc, Matej
    Kulig, Waldemar
    Lamber, Antti
    Loison, Claire
    Lyubartsev, Alexander
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Miettinen, Markus S.
    Monticelli, Luca
    Maatta, Jukka
    Ollila, O. H. Samuli
    Retegan, Marius
    Rog, Tomasz
    Santuz, Hubert
    Tynkkynen, Joona
    Toward Atomistic Resolution Structure of Phosphatidylcholine Headgroup and Glycerol Backbone at Different Ambient Conditions2015In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 119, no 49, p. 15075-15088Article in journal (Refereed)
    Abstract [en]

    Phospholipids are essential building blocks of biological membranes. Despite a vast amount of very accurate experimental data, the atomistic resolution structures sampled by the glycerol backbone and choline headgroup in phoshatidylcholine bilayers are not known. Atomistic resolution molecular dynamics simulations have the potential to resolve the structures, and to give an arrestingly intuitive interpretation of the experimental data, but only if the simulations reproduce the data within experimental accuracy. In the present work, we simulated phosphatidylcholine (PC) lipid bilayers with 13 different atomistic models, and compared simulations with NMR. experiments in terms of the highly structurally sensitive C-H bond vector order parameters. Focusing on the glycerol backbone and choline headgroups, we showed that the order parameter comparison can be used to judge the atomistic resolution structural accuracy of the models. Accurate models, in turn, allow molecular dynamics simulations to be used as an interpretation tool that translates these NMR data into a dynamic three-dimensional representation of biomolecules in biologically relevant conditions. In addition to lipid bilayers in fully hydrated conditions, we reviewed previous experimental data for dehydrated bilayers and cholesterol-containing bilayers, and interpreted them with simulations. Although none of the existing models reached experimental accuracy, by critically comparing them we were able to distill relevant chemical information: (1) increase of choline order parameters indicates the P-N vector tilting more parallel to the membrane, and (2) cholesterol induces only minor changes to the PC (glycerol backbone) structure. This work has been done as a fully open collaboration, using nmrlipids.blogspot.fi as a communication platform; all the scientific contributions were made publicly on this blog. During the open research process, the repository holding our simulation trajectories and files (https://zenodo.org/collection/user-nmrlipids) has become the most extensive publicly available collection of molecular dynamics simulation trajectories of lipid bilayers.

  • 176. Bothe, O.
    et al.
    Jungclaus, J. H.
    Zanchettin, D.
    Zorita, E.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Climate of the last millennium: ensemble consistency of simulations and reconstructions2013In: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 9, no 3, p. 1089-1110Article in journal (Refereed)
    Abstract [en]

    Are simulations and reconstructions of past climate and its variability consistent with each other? We assess the consistency of simulations and reconstructions for the climate of the last millennium under the paradigm of a statistically indistinguishable ensemble. In this type of analysis, the null hypothesis is that reconstructions and simulations are statistically indistinguishable and, therefore, are exchangeable with each other. Ensemble consistency is assessed for Northern Hemisphere mean temperature, Central European mean temperature and for global temperature fields. Reconstructions available for these regions serve as verification data for a set of simulations of the climate of the last millennium performed at the Max Planck Institute for Meteorology. Consistency is generally limited to some sub-domains and some sub-periods. Only the ensemble simulated and reconstructed annual Central European mean temperatures for the second half of the last millennium demonstrates unambiguous consistency. Furthermore, we cannot exclude consistency of an ensemble of reconstructions of Northern Hemisphere temperature with the simulation ensemble mean. If we treat simulations and reconstructions as equitable hypotheses about past climate variability, the found general lack of their consistency weakens our confidence in inferences about past climate evolutions on the considered spatial and temporal scales. That is, our available estimates of past climate evolutions are on an equal footing but, as shown here, inconsistent with each other.

  • 177. Brand, Stephen K.
    et al.
    Schmidt, Joel E.
    Deem, Michael W.
    Daeyaert, Frits
    Ma, Yanhang
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). ShanghaiTech University, China.
    Orazov, Marat
    Davis, Mark E.
    Enantiomerically enriched, polycrystalline molecular sieves2017In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 114, no 20, p. 5101-5106Article in journal (Refereed)
    Abstract [en]

    Zeolite and zeolite-like molecular sieves are being used in a large number of applications such as adsorption and catalysis. Achievement of the long-standing goal of creating a chiral, polycrystalline molecular sieve with bulk enantioenrichment would enable these materials to perform enantioselective functions. Here, we report the synthesis of enantiomerically enriched samples of a molecular sieve. Enantiopure organic structure directing agents are designed with the assistance of computational methods and used to synthesize enantioenriched, polycrystalline molecular sieve samples of either enantiomer. Computational results correctly predicted which enantiomer is obtained, and enantiomeric enrichment is proven by high-resolution transmission electron microscopy. The enantioenriched and racemic samples of the molecular sieves are tested as adsorbents and heterogeneous catalysts. The enantioenriched molecular sieves show enantioselectivity for the ring opening reaction of epoxides and enantioselective adsorption of 2-butanol (the R enantiomer of the molecular sieve shows opposite and approximately equal enantioselectivity compared with the S enantiomer of the molecular sieve, whereas the racemic sample of the molecular sieve shows no enantioselectivity).

  • 178.
    Brandt, Erik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Fluctuating hydrodynamics simulations of coarse-grained lipid membranes under steady-state conditions and in shear flow2013In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 88, no 1, p. 012714-Article in journal (Refereed)
    Abstract [en]

    The stochastic Eulerian-Lagrangian method (SELM) is used to simulate coarse-grained lipid membrane models under steady-state conditions and in shear flow. SELM is an immersed boundary method which combines the efficiency of particle-based simulations with the realistic solvent dynamics provided by fluctuating hydrodynamics. Membrane simulations in SELM are shown to give structural properties in accordance with equilibrium statistical mechanics and dynamic properties in agreement with previous simulations of highly detailed membrane models in explicit solvent. Simulations of sheared membranes are used to calculate surface shear viscosities and inter-monolayer friction coefficients. The membrane models are shown to be shear thinning under a wide range of applied shear rates.

  • 179.
    Brandt, Erik G.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Agosta, Lorenzo
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lyubartsev, Alexander P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Reactive wetting properties of TiO2 nanoparticles predicted by ab initio molecular dynamics simulations2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 27, p. 13385-13398Article in journal (Refereed)
    Abstract [en]

    Small-sized wet TiO2 nanoparticles have been investigated by ab initio molecular dynamics simulations. Chemical and physical adsorption of water on the TiO2-water interface was studied as a function of water content, ranging from dry nanoparticles to wet nanoparticles with monolayer coverage of water. The surface reactivity was shown to be a concave function of water content and driven by surface defects. The local coordination number at the defect was identified as the key factor to decide whether water adsorption proceeds through dissociation or physisorption on the surface. A consistent picture of TiO2 nanoparticle wetting at the microscopic level emerges, which corroborates existing experimental data and gives further insight into the molecular mechanisms behind nanoparticle wetting. These calculations will facilitate the engineering of metal oxide nanoparticles with a controlled catalytic water activity.

  • 180.
    Brandt, Erik G.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lyubartsev, Alexander P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Molecular Dynamics Simulations of Adsorption of Amino Acid Side Chain Analogues and a Titanium Binding Peptide on the TiO2 (100) Surface2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 32, p. 18126-18139Article in journal (Refereed)
    Abstract [en]

    Adsorption profiles and adsorption free energies were determined for the side chain analogues of the 20 naturally occurring amino acids and a titanium binding peptide on the TiO2 (100) surface. Microsecond simulations with umbrella sampling and metadynamics were used to sample the free energy barriers associated with desolvation of strongly bound water molecules at the TiO2 surface. Polar and aromatic side chain analogues that hydrogen bond either to surface waters or directly to the metal oxide surface were found to be the strongest binders. Further, adsorption simulations of a 6 residue titanium binding peptide identified two binding modes on TiO2 (100). The peptide structure with lowest free energy was shown to be stabilized by a salt bridge between the end termini. A comparison between the free energies of the side chain analogues of the peptide sequence and the peptide itself shows that the free energy contributions are not additive. The simulations emphasize that tightly bound surface waters play a key role for peptide and protein structures when bound to inorganic surfaces in biological environments.

  • 181.
    Brandt, Erik G.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lyubartsev, Alexander P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Systematic Optimization of a Force Field for Classical Simulations of TiO2-Water Interfaces2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 32, p. 18110-18125Article in journal (Refereed)
    Abstract [en]

    Atomistic force field parameters were developed for the TiO2-water interface by systematic optimization with respect to experimentally determined crystal structures (lattice parameters) and surface thermodynamics (water adsorption enthalpy). Optimized force field parameters were determined for the two cases where TiO2 was modeled with or without covalent bonding. The nonbonded TiO2 model can be used to simulate different TiO2 phases, while the bonded TiO2 model is particularly useful for simulations of nanosized TiO2 and biomatter, including protein-surface and nanoparticle-biomembrane simulations. The procedure is easily generalized to parametrize interactions between other inorganic surfaces and biomolecules.

  • 182.
    Brant Carvalho, Paulo H. B.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mace, Amber
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bull, Craig L.
    Funnell, Nicholas P.
    Tulk, Chris A.
    Andersson, Ove
    Häussermann, Ulrich
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Elucidation of the pressure induced amorphization of tetrahydrofuran clathrate hydrate2019In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 150, no 20, article id 204506Article in journal (Refereed)
    Abstract [en]

    The type II clathrate hydrate (CH) THF center dot 17 H2O (THF = tetrahydrofuran) is known to amorphize on pressurization to similar to 1.3 GPa in the temperature range 77-140 K. This seems to be related to the pressure induced amorphization (PIA) of hexagonal ice to high density amorphous (HDA) ice. Here, we probe the PIA of THF-d(8)center dot 17 D2O (TDF-CD) at 130 K by in situ thermal conductivity and neutron diffraction experiments. Both methods reveal amorphization of TDF-CD between 1.1 and 1.2 GPa and densification of the amorphous state on subsequent heating from 130 to 170 K. The densification is similar to the transition of HDA to very-high-density-amorphous ice. The first diffraction peak (FDP) of the neutron structure factor function, S(Q), of amorphous TDF-CD at 130 K appeared split. This feature is considered a general phenomenon of the crystalline to amorphous transition of CHs and reflects different length scales for D-D and D-O correlations in the water network and the cavity structure around the guest. The maximum corresponding to water-water correlations relates to the position of the FDP of HDA ice at similar to 1 GPa. Upon annealing, the different length scales for water-water and water-guest correlations equalize and the FDP in the S(Q) of the annealed amorph represents a single peak. The similarity of local water structures in amorphous CHs and amorphous ices at in situ conditions is confirmed from molecular dynamics simulations. In addition, these simulations show that THF guest molecules are immobilized and retain long-range correlations as in the crystal.

  • 183. Breistein, Palle
    et al.
    Johansson, Jonas
    Ibrahem, Ismail
    Lin, Shuangzheng
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Deiana, Luca
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Cordova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    One-Step Catalytic Enantioselective a-Quaternary 5-Hydroxyproline Synthesis: An Asymmetric Entry to Highly Functionalized a-Quaternary Proline Derivatives2012In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 354, no 6, p. 1156-1162Article in journal (Refereed)
    Abstract [en]

    The highly enantioselective cascade reaction between N-protected a-cyanoglycine esters and a,beta-unsaturated aldehydes is disclosed. The reaction represents a one-step entry to polysubstituted 5-hydroxyproline derivatives having a quaternary a-stereocenter generally in high yields with up to >95:5 dr and 99:1 er. It is also a direct catalytic two-step entry to functionalized a-quaternary proline derivatives.

  • 184. Brent, Rhea
    et al.
    Cubillas, Pablo
    Stevens, Sam M.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Jelfs, Kim E.
    Umemura, Ayako
    Gebbie, James T.
    Slater, Ben
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Holden, Mark A.
    Anderson, Michael W.
    Unstitching the Nanoscopic Mystery of Zeolite Crystal Formation2010In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, no 39, p. 13858-13868Article in journal (Refereed)
    Abstract [en]

    A molecular-scale understanding of crystal growth is critical to the development of important materials such as pharmaceuticals, semiconductors and catalysts. Only recently has this been possible with the advent of atomic force microscopy that permits observation of nanoscopic features on solid surfaces under a liquid or solution environment. This allows in Situ measurement of important chemical transformations such as crystal growth and dissolution. Further, the microscope can access not only an accurate height measurement of surface topography, important to deduce structural elements, but also the forces involved during nanoscopic processes. We have discovered that it is possible to use these features to "illuminate" critical nanoscopic chemical events at crystal surfaces and at the same time extract the associated energies and unstitch the details of the stepwise mechanism of growth and dissolution. This approach has been developed using nanoporous crystals of the heterogeneous catalyst zeolite L; however, in principle the approach could be adapted to many crystal growth problems.

  • 185. Brent, Rhea
    et al.
    Stevens, Sam M.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Anderson, Michael W.
    Coaxial Core Shell Overgrowth of Zeolite L - Dependence on Original Crystal Growth Mechanism2010In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, no 12, p. 5182-5186Article in journal (Refereed)
    Abstract [en]

    In this study, the first reported core-shell material combining zeolite L (LTL) and barium-exchanged zeolite L (Ba-LTL) is described The use of atomic force microscopy to probe the LTL surface growth mechanism was employed to understand the growth pattern of the resultant Ba-LTL coaxial overgrowth layer Additionally the dependence of the original crystal surface on the resulting habit of the Ba-LTL core-shell layer is explained High-resolution scanning electron microscopy (HRSEM) was employed to observe the fine detail of the Ba-LTL layer, and cross-sectional polishing was used to view the boundary between the two crystalline materials

  • 186. Brinkmann, Andreas
    et al.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Central-transition double-quantum sideband NMR spectroscopy of half-integer quadrupolar nuclei: estimating internuclear distances and probing clusters within multi-spin networks2014In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 15, p. 7037-7050Article in journal (Refereed)
    Abstract [en]

    We introduce a strategy to estimate the size of clusters of recoupled homonuclear half-integer quadrupolar nuclei under magic-angle spinning (MAS) conditions, by combining double-quantum (2Q) sideband NMR experiments with an approximate numerical analysis based on the summation of all spin-pairs present over a given radius of the structure. The experiment relies solely on the evolution of homonuclear 2Q coherences (2QC) among the central-transitions (CT) of half-integer spins and is suitable for probing clusters in network structures, such as those encountered in large groups of oxide-based materials. Experimental B-11, Na-23 and Al-27 NMR results are presented on bis(catecholato)diboron, Na2SO4 and Al2O3, respectively; in each case, the growth of the spin-cluster size was monitored from a series of experiments that employed progressively lengthened 2QC excitation intervals. Our new approach is the first option for probing larger constellations of half-integer spins; it provides similar information as the multiple-quantum spin counting experiment, which is well-established for spin-1/2 applications but has hitherto not been demonstrated for half-integer spins undergoing MAS. We also discuss various options for determining the internuclear distance within a (nearly) isolated pair of half-integer spins by comparing the experimental 2Q sideband NMR spectra with results from numerical simulations involving various degrees of approximation.

  • 187. Brinkmann, Andreas
    et al.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Estimating internuclear distances between half-integer quadrupolar nuclei by central-transition double-quantum sideband NMR spectroscopy2011In: Canadian journal of chemistry (Print), ISSN 0008-4042, E-ISSN 1480-3291, Vol. 89, no 7, p. 892-899Article in journal (Refereed)
    Abstract [en]

    We demonstrate the estimation of homonuclear dipolar couplings, and thereby internuclear distances, between half-integer spin quadrupolar nuclei by central-transition (CT) double-quantum (2Q) sideband nuclear magnetic resonance (NMR) spectroscopy. It is shown that the rotor-encoded sideband amplitudes from CT 2Q coherences in the indirect dimension of the two-dimensional NMR spectrum are sensitive probes of the magnitude of the homonuclear dipolar coupling, but are significantly less affected by other NMR parameters such as the magnitudes and orientations of the electric field gradient tensors. Experimental results of employing the R2(2)(1)R2(2)(-1) recoupling sequence to the (11)B spin pair of bis(catecholato)diboron resulted in an estimation of the internuclear B-B distance as (169.6 +/- 3) pm, i.e., with a relative uncertainty of +/- 2%, and in excellent agreement with the distance of 167.8 pm determined by single-crystal X-ray diffraction.

  • 188. Brouwer, Darren H.
    et al.
    Cadars, Sylvian
    Eckert, Juergen
    Liu, Zheng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Chmelka, Bradley F.
    A General Protocol for Determining the Structures of Molecularly Ordered but Noncrystalline Silicate Frameworks2013In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 15, p. 5641-5655Article in journal (Refereed)
    Abstract [en]

    A general protocol is demonstrated for determining the structures of molecularly ordered but noncrystalline solids, which combines constraints provided by X-ray diffraction (XRD), one- and two-dimensional solid-state nuclear magnetic resonance (NMR) spectroscopy, and first-principles quantum chemical calculations. The approach is used to determine the structure(s) of a surfactant-directed layered silicate with short-range order in two dimensions but without long-range periodicity in three-dimensions (3D). The absence of long-range 3D molecular order and corresponding indexable XRD reflections precludes determination of a space group for this layered silicate. Nevertheless, by combining structural constraints obtained from solid-state Si-29 NMR analyses, including the types and relative populations of distinct Si-29 sites, their respective Si-29-O-Si-29 connectivities and separation distances, with unit cell parameters (though not space group symmetry) provided by XRD, a comprehensive search of candidate framework structures leads to the identification of a small number of candidate structures that are each compatible with all of the experimental data. Subsequent refinement of the candidate structures using density functional theory calculations allows their evaluation and identification of best framework representations, based on their respective lattice energies and quantitative comparisons between experimental and calculated Si-29 isotropic chemical shifts and (2)J(Si-29-O-Si-29) scalar couplings. The comprehensive analysis identifies three closely related and topologically equivalent framework configurations that are in close agreement with all experimental and theoretical structural constraints. The subtle differences among such similar structural models embody the complexity of the actual framework(s), which likely contain coexisting or subtle distributions of structural order that are intrinsic to the material.

  • 189. Brunatova, Ereza
    et al.
    Matej, Zdenek
    Oleynikov, Peter
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Vesely, Josef
    Danis, Stanislav
    Popelkova, Daniela
    Kuzel, Radomir
    Thermal stability of titanate nanorods and titania nanowires formed from titanate nanotubes by heating2014In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 98, p. 26-36Article in journal (Refereed)
    Abstract [en]

    The structure of titanate nanowires was studied by a combination of powder X-ray diffraction (XRD) and 3D precession electron diffraction. Titania nanowires and titanate nanorods were prepared by heating of titanate nanotubes. The structure of final product depended on heating conditions. Titanium nanotubes heated in air at a temperature of 850 degrees C decomposed into three phases Na2Ti6O13 (nanorods) and two phases of TiO2 anatase and rutile. At higher temperatures the anatase form of TiO2 transforms into rutile and the nanorods change into rutile nanoparticles. By contrast, in the vacuum only anatase phases of TiO2 were obtained by heating at 900 degrees C. The anatase transformation into ruffle began only after a longer time of heating at 1000 degrees C. For the description of anisotropic XRD line broadening in the total powder pattern fitting by the program MSTRUCT a model of nanorods with elliptical base was included in the software. The model parameters rod length, axis size of the elliptical base, the ellipse flattening parameter and twist of the base could be refined. Variation of particle shapes with temperature was found.

  • 190. Brunatova, Tereza
    et al.
    Popelkova, Daniela
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Oleynikov, Peter
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Danis, Stanislav
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kuzel, Radomir
    Study of titanate nanotubes by X-ray and electron diffraction and electron microscopy2014In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 87, p. 166-171Article in journal (Refereed)
    Abstract [en]

    The structure of titanate nanotubes (Ti-NTs) was studied by a combination of powder X-ray diffraction (PXRD), electron diffraction and high resolution transmission electron microscopy (HRTEM). Ti-NTs are prepared by hydrothermal treatment of TiO2 powder. The structure is identified by powder X-ray diffraction as the one based on the structure of H2Ti2O5 center dot H2O phase. The same structure is obtained by projected potential from HRTEM through-focus image series. The structure is verified by simulated PXRD pattern with the aid of the Debye formula. The validity of the model is tested by computing Fourier transformation of a single nanotube which is proportional to measured electron diffraction intensities. A good agreement of this calculation with measured precession electron diffraction data is achieved.

  • 191.
    Bruneau, Alexandre
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gustafson, Karl P. J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yuan, Ning
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Swedish University of Agricultural Sciences, Sweden.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Persson, Ingmar
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of Benzofurans and Indoles from Terminal Alkynes and Iodoaromatics Catalyzed by Recyclable Palladium Nanoparticles Immobilized on Siliceous Mesocellular Foam2017In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 52, p. 12886-12891Article in journal (Refereed)
    Abstract [en]

    Herein, we report on the utilization of a heterogeneous catalyst, consisting of Pd nanoparticles supported on a siliceous mesocellular foam (Pd-0-AmP-MCF), for the synthesis of heterocycles. Reaction of o-iodophenols and protected o-iodoanilines with acetylenes in the presence of a Pd nanocatalyst produced 2-substituted benzofurans and indoles, respectively. In general, the catalytic protocol afforded the desired products in good to excellent yields under mild reaction conditions without the addition of ligands. Moreover, the structure of the reported Pd nanocatalyst was further elucidated with extended X-ray absorption fine-structure spectroscopy, and it was proven that the catalyst could be recycled multiple times without significant loss of activity.

  • 192. Bueken, Bart
    et al.
    Van Velthoven, Niels
    Willhammar, Tom
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). University of Antwerp, Belgium.
    Stassin, Timothee
    Stassen, Ivo
    Keen, David A.
    Baron, Gino V.
    Denayer, Joeri F. M.
    Ameloot, Rob
    Bals, Sara
    De Vos, Dirk
    Bennett, Thomas D.
    Gel-based morphological design of zirconium metal-organic frameworks2017In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 8, no 5, p. 3939-3948Article in journal (Refereed)
    Abstract [en]

    The ability of metal-organic frameworks (MOFs) to gelate under specific synthetic conditions opens up new opportunities in the preparation and shaping of hierarchically porous MOF monoliths, which could be directly implemented for catalytic and adsorptive applications. In this work, we present the first examples of xero-or aerogel monoliths consisting solely of nanoparticles of several prototypical Zr4+-based MOFs: UiO-66-X (X - H, NH2, NO2, (OH)(2)), UiO-67, MOF-801, MOF-808 and NU-1000. High reactant and water concentrations during synthesis were observed to induce the formation of gels, which were converted to monolithic materials by drying in air or supercritical CO2. Electron microscopy, combined with N-2 physisorption experiments, was used to show that irregular nanoparticle packing leads to pure MOF monoliths with hierarchical pore systems, featuring both intraparticle micropores and interparticle mesopores. Finally, UiO-66 gels were shaped into monolithic spheres of 600 mm diameter using an oil-drop method, creating promising candidates for packed-bed catalytic or adsorptive applications, where hierarchical pore systems can greatly mitigate mass transfer limitations.

  • 193. Bueno-Alejo, Carlos J.
    et al.
    Villaescusa, Luis A.
    Garcia-Bennett, Alfonso E.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Supramolecular Transcription of Guanosine Monophosphate into Mesostructured Silica2014In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 53, no 45, p. 12106-12110Article in journal (Refereed)
    Abstract [en]

    There is large interest in replicating biological supramolecular structures in inorganic materials that are capable of mimicking biological properties. The use of 5-guanosine monophosphate in the presence of Na+ and K+ ions as a supramolecular template for the synthesis of well-ordered mesostructured materials is reported here. Mesostructured particles with the confined template exhibit high structural order at both meso-and atomic scales, with a lower structural symmetry in the columnar mesophase. Although a chiral space group can not be deduced from X-ray diffraction, analysis by electron microscopy and circular dichroism confirms a chiral stacking arrangement along the c-axis. Guanosine monophosphate based mesophases thus illustrate the possibility for specific molecular imprinting of mesoporous materials by genetic material and the potential for higher definition in molecular recognition.

  • 194. Buixaderas, E.
    et al.
    Bovtun, V.
    Kempa, M.
    Savinov, M.
    Nuzhnyy, D.
    Kadlec, F.
    Vanek, P.
    Petzelt, J.
    Eriksson, M.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Broadband dielectric response and grain-size effect in K0.5Na0.5NbO3 ceramics2010In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 107, no 1, p. 14111-Article in journal (Refereed)
    Abstract [en]

    Dielectric spectra of two K0.5Na0.5NbO3 ceramics with different grain sizes (10 and 0.5 mu m) were measured from 10(2) to 10(14) Hz in a broad temperature range. The sequence of first-order phase transitions (cubic-tetragonal-orthorhombic-rhombohedral) was detected by differential scanning calorimetry, dielectric spectroscopy, and time-domain terahertz spectroscopy. The grain size affects all the phase transitions, which are more smeared in the small-grain sample. In the large-grain ceramics, two well-separated near-Debye relaxations are seen in the tetragonal phase, which suddenly merge on cooling across the tetragonal-orthorhombic transition, and on further cooling the lower-frequency relaxation strongly broadens. On reducing the grain size, the higher-frequency relaxation shifts from similar to 1 to similar to 20 GHz and the lower-frequency one strongly broadens. Without quantitative understanding, these effects could be assigned to domain-wall dynamics and its temperature and grain-size dependences. Similar to pure KNbO3, an overlapped central-mode-soft-mode type excitation was detected in the terahertz range related to the effective hopping and oscillations of the off-centered Nb ions in a multiwell potential.

  • 195. Burks, T.
    et al.
    Avila, M.
    Akhtar, Farid
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gothelid, M.
    Lansaker, P. C.
    Toprak, M. S.
    Muhammed, M.
    Uheida, A.
    Studies on the adsorption of chromium(VI) onto 3-Mercaptopropionic acid coated superparamagnetic iron oxide nanoparticles2014In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 425, p. 36-43Article in journal (Refereed)
    Abstract [en]

    Chromium (Cr) in the form of Cr(VI) is deemed toxic in water due to its mutagenic and carcinogenic properties. For the successful removal of Cr(VI), we demonstrate a novel adsorbent consisting of superparamagnetic iron oxide nanoparticles (SPION) functionalized with 3-Mercaptopropionic acid (3-MPA). Fourier transform infrared spectroscopy (FT-IR) confirmed the functionalization of nanoparticles and presence of sulfonate groups. Batch adsorption experiments showed that the functionalized adsorbent recovered 45 mg of Cr(VI)/g of 3-MPA coated SPION at initial concentration of 50 mg/L aqueous solution at pH 1 with less than 1% of Fe dissolution from SPION. The results from X-ray photoelectron spectroscopy confirmed that Cr(VI) chemisorbed onto the adsorbent. Hence, the XPS spectra did not indicate any reduction of Cr(VI) to Cr(III) upon adsorption. The adsorption data were better fitted for the Freundlich model. Moreover, the Cr(VI) adsorption kinetics on functionalized SPION followed a pseudo-second order rate, revealing chemisorption as the dominant mechanism. The high Cr(VI) removal, rapid adsorption kinetics and stability of adsorbent indicate that 3-MPA coated SPION could be an efficient adsorbent for the removal of Cr(VI).

  • 196. Buscaglia, Maria Teresa
    et al.
    Buscaglia, Vincenzo
    Curecheriu, Lavinia
    Postolache, Petronel
    Mitoseriu, Liliana
    Ianculescu, Adelina C.
    Vasile, Bogdan S.
    Zhao, Zhe
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nanni, Paolo
    Fe2O3@BaTiO3 core-shell particles as reactive precursors for the preparation of multifunctional composites containing different magnetic phases2010In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 22, no 16, p. 4740-4748Article in journal (Refereed)
    Abstract [en]

    Well-designed reactive precursors and templates allow for careful control of solid-state reactions at the nanoscale level, thus enabling the fabrication of materials with specific microstructures and properties. In this study, Fe2O3@BaTiO3 core−shell particles have been used as precursors for the in situ fabrication of multifunctional composites containing a dielectric/ferroelectric phase and two magnetic phases with contrasting coercivities (Fe2O3/Fe3O4, BaFe12O19/Ba12Fe28Ti15O84). The formation of new magnetic phases occurs during sintering or post-annealing via reaction between BaTiO3 and Fe2O3. The starting powders have been prepared using a multistep process that combines colloidal chemistry methods and a solid-state reaction. The nature and the amount of the magnetic phases and, consequently, the final magnetic properties of the composite can be controlled by varying the relative amount of Fe2O3 (30 or 50 vol%), the densification method (conventional or spark plasma sintering), and the processing temperature. The composites show constricted magnetic hysteresis loops with a coercivity of 0.1−2.5 kOe and a saturation magnetization of 5−16 emu/g. Composites obtained from powders containing 30 vol% Fe2O3 show, at temperatures of 20−80 °C and frequencies between 10 kHz and 1 MHz, a relative dielectric constant of 50 and dielectric losses of <10%.

  • 197. Buxhuku, Mika
    et al.
    Hansen, Vidar
    Oleynikov, Peter
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Gjonnes, Jon
    The Determination of Rotation Axis in the Rotation Electron Diffraction Technique2013In: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 19, no 5, p. 1276-1280Article in journal (Refereed)
    Abstract [en]

    Methods to determine the rotation axis using the rotation electron diffraction technique are described. A combination of rotation axis tilt, beam tilt, and simulated experimental diffraction patterns with nonintegers zone axis has been used. Accurate knowledge of the crystallographic direction of the incident beam for deducing the excitation error of reflections simultaneously near Bragg positions is essential in quantitative electron diffraction. Experimental patterns from CoP3 are used as examples.

  • 198. Candelario, Victor M.
    et al.
    Moreno, Rodrigo
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Guiberteau, Fernando
    Ortiz, Angel L.
    Liquid-phase assisted spark-plasma sintering of SiC nanoceramics and their nanocomposites with carbon nanotubes2017In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 37, no 5, p. 1929-1936Article in journal (Refereed)
    Abstract [en]

    The appropriate conditions for liquid-phase assisted spark-plasma sintering (SPS) were identified for the fabrication of both SiC nanoceramics and their nanocomposites with carbon nanotubes (CNTs). A parametric study of the nanoceramics and nanocomposites with a given type of CNTs showed that the SPS temperature (as measured by the radial optical pyrometer) optimizing their densification, nanograin size, and mechanical properties is 1700 degrees C (soaking for a few minutes), below which there is incomplete densification, and above which there is obvious grain growth with no benefit in hardness or toughness in the case of the nanoceramics, and prejudicial to both properties in the case of the nanocomposites due to the CNT degradation. It was also shown that the nanocomposites have smaller nanograins than their nanoceramic counterparts, and are softer but tougher. Extension to nanocomposites with different types of CNTs confirmed these trends, and showed that the CNT features do not condition the densification, microstructure or mechanical properties of these nanocomposites.

  • 199. Candelario, Victor M.
    et al.
    Moreno, Rodrigo
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ortiz, Angel L.
    Aqueous colloidal processing of nano-SiC and its nano-Y3Al5O12 liquid-phase sintering additives with carbon nanotubes2015In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 35, no 13, p. 3363-3368Article in journal (Refereed)
    Abstract [en]

    Carbon nanotubes (CNTs) have occasionally been observed to benefit the aqueous colloidal processing of nano-SiC with its nano-Y3Al5O12 liquid-phase-sintering additives. Experimental evidence is here presented for a broad set of CNTs with different morphology and/or surface functionalization confirming that CNTs (7 vol.% addition), regardless of their features, prevent the coagulation of these nanoceramic suspensions, whence it is inferred that aqueous colloidal processing is well-suited for the environmentally friendly preparation of the homogeneous mixtures of nanoceramic particles and CNTs required for the fabrication of CNT-reinforced ceramic matrix nanocomposites. Furthermore, it is shown that surface-functionalized CNTs seem to work better than deflocculated CNTs for the preparation of stable concentrated colloidal suspensions, whose rheological properties are in general very close, but with thinner CNTs being nonetheless preferable. Finally, the feasibility is demonstrated of fabricating SiC/CNT nanocomposites by aqueous colloidal processing followed by liquid-phase assisted spark-plasma sintering.

  • 200.
    Cantillana, Tatiana
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    (2S)-1,1-Dichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl)ethane2009In: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 65, p. OO297-U1934Article in journal (Refereed)
    Abstract [en]

    The title compound, C14H10Cl4, is easily crystallized while the other enantiomorph only forms an oil upon crystallization attempts. The title compound has a considerably higher density, rho similar or equal to 1.562 Mg m(-3) compared to the racemic substance, rho similar or equal to 1.514 Mg m(-3). This is supported by the fact there are two intermolecular halogen-halogen contacts in the title compound compared with only one the racemic compound. The dihedral angle between the two phenyl rings is 76.83 (5)degrees

1234567 151 - 200 of 1954
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