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  • 1. Amaya, Andrew J.
    et al.
    Pathak, Harshad
    Modak, Viraj P.
    Laksmono, Hartawan
    Loh, N. Duane
    Sellberg, Jonas A.
    Stockholm University, Faculty of Science, Department of Physics. SLAC National Accelerator Laboratory, United States; KTH Royal Institute of Technology, Sweden.
    Sierra, Raymond G.
    McQueen, Trevor A.
    Hayes, Matt J.
    Williams, Garth J.
    Messerschmidt, Marc
    Boutet, Sebastien
    Bogan, Michael J.
    Nilsson, Anders
    Stockholm University, Faculty of Science, Department of Physics. SLAC National Acceleratory Laboratory, United States.
    Stan, Claudiu A.
    Wyslouzil, Barbara E.
    How Cubic Can Ice Be?2017In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 8, no 14, 3216-3222 p.Article in journal (Refereed)
    Abstract [en]

    Using an X-ray laser, we investigated the crystal structure of ice formed by homogeneous ice nucleation in deeply supercooled water nanodrops (r approximate to 10 nm) at similar to 225 K The nanodrops were formed by condensation of vapor in a supersonic nozzle, and the ice was probed within 100 mu s of freezing using femtosecond wide-angle X-ray scattering at the Linac Coherent Light Source free-electron X-ray laser. The X-ray diffraction spectra indicate that this ice has a metastable, predominantly cubic structure; the shape of the first ice diffraction peak suggests stacking-disordered ice with a cubicity value, chi, in the range of 0.78 +/- 0.05. The cubicity value determined here is higher than those determined in experiments with micron-sized drops but comparable to those found in molecular dynamics simulations. The high cubicity is most likely caused by the extremely low freezing temperatures and by the rapid freezing, which occurs on a similar to 1 mu s time scale in single nanodroplets.

  • 2. Battiston, S.
    et al.
    Boldrini, S.
    Saleemi, Mohsin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). KTH Royal Institute of Technology, Sweden.
    Famengo, A.
    Fiameni, S.
    Toprak, M. S.
    Fabrizio, M.
    Influence of Al and Mg Addition on Thermoelectric Properties of Higher Manganese Silicides Obtained by Reactive Sintering2017In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 17, no 3, 1668-1673 p.Article in journal (Refereed)
    Abstract [en]

    Higher manganese silicides (HMS), represented by MnSix (x = 1.71-1.75), are promising p-type candidates for thermoelectric (TE) energy harvesting systems at intermediate temperature range. The materials are very attractive as they may replace lead based compounds due to their nontoxicity, low cost of starting materials, and high thermal and chemical stability. Dense pellets were obtained through fast reactive sintering by spark plasma sintering (SPS). The addition -or nanoinclusion, of Al and Mg permitted the figure of merit enhancement of the material obtained with this technique, reaching the highest value of 0.40 at 600 degrees C. Morphology, composition and crystal structure of the samples were characterized by electron microscopies, energy dispersive X-ray spectroscopy, and X-ray diffraction analyses, respectively.

  • 3.
    Bayat, Narges
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Lopes, V. R.
    Sanchez-Dominguez, M.
    Lakshmanan, R.
    Rajarao, G. K.
    Cristobal, S.
    Assessment of functionalized iron oxide nanoparticles in vitro: introduction to integrated nanoimpact index2015In: Environmental Science: Nano, ISSN 2051-8153, Vol. 2, no 4, 380-394 p.Article in journal (Refereed)
    Abstract [en]

    Functionalization of super paramagnetic iron oxide NPs (SPIONs) with different coatings renders them with unique physicochemical properties that allow them to be used in a broad range of applications such as drug targeting and water purification. However, it is required to fill the gap between the promises of any new functionalized SPIONs and the effects of these coatings on the NPs safety. Nanotoxicology is offering diverse strategies to assess the effect of exposure to SPIONs in a case-by-case manner but an integrated nanoimpact scale has not been developed yet. We have implemented the classical integrated biological response (IBR) into an integrated nanoimpact index (INI) as an early warning scale of nano-impact based on a combination of toxicological end points such as cell proliferation, oxidative stress, apoptosis and genotoxicity. Here, the effect of SPIONs functionalized with tri-sodium citrate (TSC), polyethylenimine (PEI), aminopropyl-triethoxysilane (APTES) and Chitosan (chitosan) were assessed on human keratinocytes and endothelial cells. Our results show that endothelial cells were more sensitive to exposure than keratinocytes and the initial cell culture density modulated the toxicity. PEI-SPIONs had the strongest effects in both cell types while TSC-SPIONS were the most biocompatible. This study emphasizes not only the importance of surface coatings but also the cell type and the initial cell density on the selection of toxicity assays. The INI developed here could offer an initial rationale to choose either modifying SPIONs properties to reduce its nanoimpact or performing a complete risk assessment to define the risk boundaries.

  • 4. Bejhed, Rebecca S.
    et al.
    Strömme, Maria
    Svedlindh, Peter
    Ahlford, Annika
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Strömberg, Mattias
    Magnetic nanobeads present during enzymatic amplification and labeling for a simplified DNA detection protocol based on AC susceptometry2015In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 5, no 12, 127139Article in journal (Refereed)
    Abstract [en]

    Magnetic biosensors are promising candidates for low-cost point-of-care biodiagnostic devices. For optimal efficiency it is crucial to minimize the time and complexity of the assay protocol including target recognition, amplification, labeling and read-out. In this work, possibilities for protocol simplifications for a DNA biodetection principle relying on hybridization of magnetic nanobeads to rolling circle amplification (RCA) products are investigated. The target DNA is recognized through a padlock ligation assay resulting in DNA circles serving as templates for the RCA process. It is found that beads can be present during amplification without noticeably interfering with the enzyme used for RCA (phi29 polymerase). As a result, the bead-coil hybridization can be performed immediately after amplification in a one-step manner at elevated temperature within a few minutes prior to read-out in an AC susceptometer setup, i.e. a combined protocol approach. Moreover, by recording the phase angle xi = arctan(chi ''/chi'), where chi and chi '' are the in-phase and out-of-phase components of the AC susceptibility, respectively, at one single frequency the total assay time for the optimized combined protocol would be no more than 1.5 hours, often a relevant time frame for diagnosis of cancer and infectious disease. Also, applying the phase angle method normalization of AC susceptibility data is not needed. These findings are useful for the development of point-of-care biodiagnostic devices relying on bead-coil binding and magnetic AC susceptometry.

  • 5.
    Borysov, Stanislav S.
    et al.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). KTH Royal Institute of Technology, Sweden; Los Alamos National Laboratory, USA.
    Forchheimer, Daniel
    Haviland, David B.
    Dynamic calibration of higher eigenmode parameters of a cantilever in atomic force microscopy by using tip-surface interactions2014In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 5, 1899-1904 p.Article in journal (Refereed)
    Abstract [en]

    We present a theoretical framework for the dynamic calibration of the higher eigenmode parameters (stiffness and optical lever inverse responsivity) of a cantilever. The method is based on the tip-surface force reconstruction technique and does not require any prior knowledge of the eigenmode shape or the particular form of the tip-surface interaction. The calibration method proposed requires a single-point force measurement by using a multimodal drive and its accuracy is independent of the unknown physical amplitude of a higher eigenmode.

  • 6.
    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, 13385-13398 p.Article 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.

  • 7.
    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, 18126-18139 p.Article 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.

  • 8.
    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, 18110-18125 p.Article 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.

  • 9. Carinelli, S.
    et al.
    Kühnemund, M.
    Nilsson, Mats
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Pividori, M. I.
    Yoctomole electrochemical genosensing of Ebola virus cDNA by rolling circle and circle to circle amplification2017In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 93, 65-71 p.Article in journal (Refereed)
    Abstract [en]

    This work addresses the design of an Ebola diagnostic test involving a simple, rapid, specific and highly sensitive procedure based on isothermal amplification on magnetic particles with electrochemical readout. Ebola padlock probes were designed to detect a specific L-gene sequence present in the five most common Ebola species. Ebola cDNA was amplified by rolling circle amplification (RCA) on magnetic particles. Further re-amplification was performed by circle-to-circle amplification (C2CA) and the products were detected in a double-tagging approach using a biotinylated capture probe for immobilization on magnetic particles and a readout probe for electrochemical detection by square-wave voltammetry on commercial screen-printed electrodes. The electrochemical genosensor was able to detect as low as 200 ymol, corresponding to 120 cDNA molecules of L-gene Ebola virus with a limit of detection of 33 cDNA molecules. The isothermal double-amplification procedure by C2CA combined with the electrochemical readout and the magnetic actuation enables the high sensitivity, resulting in a rapid, inexpensive, robust and user-friendly sensing strategy that offers a promising approach for the primary care in low resource settings, especially in less developed countries.

  • 10.
    Cavalca, Filippo
    et al.
    Stockholm University, Faculty of Science, Department of Physics. SLAC National Accelerator Laboratory, United States.
    Ferragut, Rafael
    Aghion, Stefano
    Eilert, André
    Stockholm University, Faculty of Science, Department of Physics. SLAC National Accelerator Laboratory, United States; Stanford University, United States.
    Diaz-Morales, Oscar
    Stockholm University, Faculty of Science, Department of Physics.
    Liu, Chang
    Stockholm University, Faculty of Science, Department of Physics.
    Koh, Ai Leen
    Hansen, Thomas W.
    Pettersson, Lars G. M.
    Stockholm University, Faculty of Science, Department of Physics.
    Nilsson, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Nature and Distribution of Stable Subsurface Oxygen in Copper Electrodes During Electrochemical CO2 Reduction2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 45, 25003-25009 p.Article in journal (Refereed)
    Abstract [en]

    Oxide-derived copper (OD-Cu) electrodes exhibit higher activity than pristine copper during the carbon dioxide reduction reaction (CO2RR) and higher selectivity toward ethylene. The presence of residual subsurface oxygen in OD-Cu has been proposed to be responsible for such improvements, although its stability under the reductive CO2RR conditions remains unclear. This work sheds light on the nature and stability of subsurface oxygen. Our spectroscopic results show that oxygen is primarily concentrated in an amorphous 1-2 nm thick layer within the Cu subsurface, confirming that subsurface oxygen is stable during CO2RR for up to 1 h at -1.15 V vs RHE. Besides, it is associated with a high density of defects in the OD-Cu structure. We propose that both low coordination of the amorphous OD-Cu surface and the presence of subsurface oxygen that withdraws charge from the copper sp- and d-bands might selectively enhance the binding energy of CO.

  • 11. Chen, Yanping
    et al.
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Huang, Shiliang
    Liang, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Peking University, China.
    Lin, Xiaohuan
    Liao, Fuhui
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Peking University, China.
    Wang, Yingxia
    Lin, Jianhua
    Gies, Hermann
    PKU-20: A new silicogermanate constructed from sti and asv layers2016In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 224, 384-391 p.Article in journal (Refereed)
    Abstract [en]

    A new silicogermanate (PKU-20) was hydrothermally synthesized using triethylisopropylammonium cation as the structure directing agent in the presence of fluoride. Its structure was determined from a combination of synchrotron single crystal X-ray diffraction and powder X-ray diffraction data. PKU-20 crystallizes in the monoclinic space group C2/m, with the lattice parameters of a = 18.5901(6) angstrom, b = 13.9118 (4) angstrom, c = 22.2614(7) angstrom and beta = 100.1514 (12)degrees. The framework of PKU-20 is constructed from an alternate stacking of sti and asv layers. The sti layer is exactly the same as that in the STI framework, while the asv layer is a new layer sliced off from the ASV framework parallel to the (112) plane. The takeout scheme of the layer is discussed on the basis of a composite building unit D4R-/au-D4R. PKU-20 possesses a two-dimensional channel system, where the 10-ring channels parallel to the [010] direction are intercrossed by 12-ring pockets along the [101] direction.

  • 12. Cho, Hae Sung
    et al.
    Miyasaka, Keiichi
    Kim, Hyungjun
    Kubota, Yoshiki
    Takata, Masaki
    Kitagawa, Susumu
    Ryoo, Ryong
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Study of Argon Gas Adsorption in Ordered Mesoporous MFI Zeolite Framework2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 48, 25300-25308 p.Article in journal (Refereed)
    Abstract [en]

    An ordered mesoporous MFI zeolite material (Meso-MFI) was prepared by using CMK-type mesoporous carbons as a hard template. The Meso-MFI exhibits both structural and adsorption differences compared to the conventional bulk MFI zeolite. To study the argon (Ar) adsorption process in Meso-MFI, an in situ gas adsorption powder X-ray diffraction (XRD) analysis was performed using synchrotron X-ray source. Structural rearrangement of the mesoporous MFI zeolite upon Ar adsorption at low temperature (83 K) was intensively studied together with Ar adsorption process in Meso-MFI. We observed that a structural transition of the Meso-MFI zeolite framework from monoclinic (P2(1)/n) to orthorhombic (Pnma) occurred at around 126 Pa at 83 K. Positions of Ar atoms are determined as a function of the Ar gas pressure through Rietveld refinement of powder XRD data. Ar atoms are observed at straight channels, sinusoidal channels, and the intersection of these channels at low pressure. As gas pressure increases, Ar atoms in the pore intersection are pulled off from the intersection toward the straight and sinusoidal channels. The pore shape of the straight channel is changed accordingly with the amount of adsorbed Ar atoms within the pores from circular to oval. These results indicate that Ar adsorption induces not only continuous rearrangement of framework atoms but also symmetry change in the Meso-MFI. A molecular simulation study combined with Rietveld refinement of in situ XRD data provided a full understanding of the adsorption process of Ar in Meso-MFI.

  • 13. Cronholm, Pontus
    et al.
    Karlsson, Hanna L.
    Hedberg, Jonas
    Lowe, Troy A.
    Winnberg, Lina
    Elihn, Karine
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Wallinder, Inger Odnevall
    Möller, Lennart
    Intracellular Uptake and Toxicity of Ag and CuO Nanoparticles: A Comparison Between Nanoparticles and their Corresponding Metal Ions2013In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 9, no 7, 970-982 p.Article in journal (Refereed)
    Abstract [en]

    An increased understanding of nanoparticle toxicity and its impact on human health is essential to enable a safe use of nanoparticles in our society. The aim of this study is to investigate the role of a Trojan horse type mechanism for the toxicity of Ag-nano and CuO-nano particles and their corresponding metal ionic species (using CuCl2 and AgNO3), i.e., the importance of the solid particle to mediate cellular uptake and subsequent release of toxic species inside the cell. The human lung cell lines A549 and BEAS-2B are used and cell death/membrane integrity and DNA damage are investigated by means of trypan blue staining and the comet assay, respectively. Chemical analysis of the cellular dose of copper and silver is performed using atomic absorption spectroscopy. Furthermore, transmission electron microscopy, laser scanning confocal microscopy, and confocal Raman microscopy are employed to study cellular uptake and particle-cell interactions. The results confirm a high uptake of CuO-nano and Ag-nano compared to no, or low, uptake of the soluble salts. CuO-nano induces both cell death and DNA damage whereas CuCl2 induces no toxicity. The opposite is observed for silver, where Ag-nano does not cause any toxicity, whereas AgNO3 induces a high level of cell death. In conclusion: CuO-nano toxicity is predominantly mediated by intracellular uptake and subsequent release of copper ions, whereas no toxicity is observed for Ag-nano due to low release of silver ions within short time periods.

  • 14. Dos Santos, Egon C.
    et al.
    Lourenco, Maicon P.
    Pettersson, Lars G. M.
    Stockholm University, Faculty of Science, Department of Physics.
    Duarte, Hélio A.
    Stability, Structure, and Electronic Properties of the Pyrite/Arsenopyrite Solid-Solid Interface-A DFT Study2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 14, 8042-8051 p.Article in journal (Refereed)
    Abstract [en]

    Pyrite is the most common sulfide in the Earth. In the presence of arsenopyrite its oxidation is delayed, and instead, the arsenopyrite increases its oxidation rate, releasing As(III) and As(V) species in the medium. DFT/plane waves calculations were performed on pyrite/arsenopyrite interface models to understand the stability, structure, and electronic properties of the interface. This is the first step to understand the influence of the inlaid arsenopyrite in the pyrite oxidation mechanism. The interface is slightly stressed with minor changes in the bond lengths and lattice parameters with respect to the pure phases. The work of adhesion and the formation energy indicate that the miscibility of the two phases is not favorable, explaining the presence of large domains of either pyrite or arsenopyrite forming bulk granular regions. The valence band of the pyrite/arsenopyrite interface has large contributions from the pyrite phase, while the conduction band has large contributions from the arsenopyrite. This is consistent with the pyrite as cathode and arsenopyrite as anode in a galvanic contact. Furthermore, the interface formation shifts the valence states upward and decreases the band gap, facilitating interfacial electron transfer.

  • 15. Dumanov, E. V.
    et al.
    Podlesny, I. V.
    Moskalenko, S. A.
    Liberman, Michael A.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Interaction of two-dimensional magnetoexcitons2017In: Physica. E, Low-Dimensional systems and nanostructures, ISSN 1386-9477, E-ISSN 1873-1759, Vol. 88, 77-86 p.Article in journal (Refereed)
    Abstract [en]

    We study interaction of the two-dimensional magnetoexcitons with in-plane wave vector (k) over right arrow (parallel to) = 0, taking into account the influence of the excited Landau levels (ELLS) and of the external electric field perpendicular to the surface of the quantum well and parallel to the external magnetic field., It is shown that the account of the ELLS gives rise to the repulsion between the spinless magnetoexcitons with (k) over right arrow (parallel to) = 0 in the Fock approximation, with the interaction constant g decreasing inverse proportional to the magnetic field strength B (g(0) similar to 1/B). In the presence of the perpendicular electric field the Rashba spin-orbit coupling (RSOC), Zeeman splitting (ZS) and nonparabolicity of the heavy-hole dispersion law affect the Landau quantization of the electrons and holes. They move along the new cyclotron orbits, change their Coulomb interactions and cause the interaction between 21) magnetoexcitons with (k) over right arrow (parallel to) = 0. The changes of the Coulomb interactions caused by the electrons and by the holes moving with new cyclotron orbits are characterized by some coefficients, which in the absence of the electric field turn to be unity. The differences between these coefficients of the electron-hole pairs forming the magnetoexcitons determine their affinities to the interactions. The interactions between the homogeneous, semihomogeneous and heterogeneous magnetoexcitons forming the symmetric states with the same signs of their affinities are attractive whereas in the case of different sign affinities are repulsive. In the heterogeneous asymmetric states the interactions have opposite signs in comparison with the symmetric states. In all these cases the interaction constant g have the dependence g(0) - 1/root B.

  • 16. El-Kemary, Maged
    et al.
    Zahran, Moustafa
    Khalifa, Shaden A. M.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Karolinska University Hospital, Sweden.
    El-Seedi, Hesham R.
    Spectral characterisation of the silver nanoparticles biosynthesised using Ambrosia maritima plant2016In: Micro & Nano Letters, ISSN 1750-0443, E-ISSN 1750-0443, Vol. 11, no 6, 311-314 p.Article in journal (Refereed)
    Abstract [en]

    Silver nanoparticles (AgNPs) were biosynthesised by reducing silver nitrate (AgNO3) using Ambrosia maritima aqueous leaves extract. The biosynthesised AgNPs were characterised by transmission electron microscope, Fourier transform infrared spectroscopy and zeta potential analyser. The nanoparticles were generally found to be spherical in shape with average size of 30 nm and were stable at zeta potential of -26.29 mV. The data collected by cyclic voltammetry, ultraviolet-visible (UV-Vis) spectrophotometer and spectrofluorophotometer proved the characteristic electrochemical and optical properties of the biosynthesised AgNPs. The metallic nanoparticles showed an anodic peak at 0.4 mV, a surface plasmon resonance peak at 437 nm and a fluorescence emission peak at the wavelength of 467 nm. In conclusion, AgNPs biosynthesised using A. maritima proved to be compatible and feasible to be studied further in in vitro and in vivo systems. Overall, the biosynthesised AgNPs can be used as a tool applied in a broad range of industrial and medical applications.

  • 17. Engström, Anna
    et al.
    Gómez de la Torre, Teresa Zardán
    Strømme, Maria
    Nilsson, Mats E.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Herthnek, David
    Detection of Rifampicin Resistance in Mycobacterium tuberculosis by Padlock Probes and Magnetic Nanobead-Based Readout2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 4, e62015Article in journal (Refereed)
    Abstract [en]

    Control of the global epidemic tuberculosis is severely hampered by the emergence of drug-resistant Mycobacterium tuberculosis strains. Molecular methods offer a more rapid means of characterizing resistant strains than phenotypic drug susceptibility testing. We have developed a molecular method for detection of rifampicin-resistant M. tuberculosis based on padlock probes and magnetic nanobeads. Padlock probes were designed to target the most common mutations associated with rifampicin resistance in M. tuberculosis, i.e. at codons 516, 526 and 531 in the gene rpoB. For detection of the wild type sequence at all three codons simultaneously, a padlock probe and two gap-fill oligonucleotides were used in a novel assay configuration, requiring three ligation events for circularization. The assay also includes a probe for identification of the M. tuberculosis complex. Circularized probes were amplified by rolling circle amplification. Amplification products were coupled to oligonucleotide-conjugated magnetic nanobeads and detected by measuring the frequency-dependent magnetic response of the beads using a portable AC susceptometer.

  • 18.
    Faure, Bertrand
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Particle interactions at the nanoscale: From colloidal processing to self-assembled arrays2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nanostructured materials are the next generation of high-performance materials, harnessing the novel properties of their nanosized constituents. The controlled assembly of nanosized particles and the design of the optimal nanostructure require a detailed understanding of particle interactions and robust methods to tune them. This thesis describes innovative approaches to these challenges, relating to the determination of Hamaker constants for iron oxide nanoparticles, the packaging of nanopowders into redispersible granules, the tuning of the wetting behavior of nanocrystals and the simulation of collective magnetic properties in arrays of superparamagnetic nanoparticles.

    The non-retarded Hamaker constants for iron oxides have been calculated from their optical properties based on Lifshitz theory. The results show that the magnitude of vdW interactions in non-polar solvents has previously been overestimated up to 10 times. Our calculations support the experimental observations that oleate-capped nanoparticles smaller than 15 nm in diameter can indeed form colloidally-stable dispersions in hydrocarbons. In addition, a simple procedure has been devised to remove the oleate-capping on the iron oxide nanoparticles, enabling their use in fluorometric assays for water remediation, with a sensitivity more than 100 times below the critical micelle concentration for non-ionic surfactants.

    Nanosized particles are inherently more difficult to handle in the dry state than larger micron-sized powders, e.g. because of poor flowability, agglomeration and potential toxicity. The rheology of concentrated slurries of TiO2 powder was optimized by the addition of sodium polyacrylate, and spray-dried into fully redispersible micron-sized granules. The polymer was embedded into the granules, where it could serve as a re-dispersing aid.

    Monte Carlo (MC) simulations have been applied to the collective magnetic behavior of nanoparticle arrays of various thicknesses. The decrease in magnetic susceptibility with the thickness observed experimentally was reproduced by the simulations. Ferromagnetic couplings in the arrays are enhanced by the finite thickness, and decrease in strength with increasing thickness. The simulations indicate the formation of vortex states with increasing thickness, along with a change in their orientation, which becomes more and more isotropic as the thickness increases.

  • 19. Gala, Fabrizio
    et al.
    Agosta, Lorenzo
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zollo, Giuseppe
    Water Kinetics and Clustering on the (101) TiO2 Anatase Surface2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 1, 450-456 p.Article in journal (Refereed)
    Abstract [en]

    (101) anatase TiO2 surface in water ambient is an important system for the interaction of biocompatible nanodevices with biological environment. Following the experimental evidence showing that water molecules are mobile at temperature as low as 190 K and tend to form clusters along the [11 (1) over bar]/[1 (11) over bar] surface directions, a complete theoretical characterization of the dynamical properties of the first water layer on the (101) anatase TiO2 surface is presented. A variety of computational techniques have been employed in the context of the transition-state theory in the harmonic regime, ranging from first-principles total energy ground-state calculations, to density functional perturbation theory, minimum energy path search, and kinetic Monte Carlo simulations, to explain the experimental results on water kinetics on the (101) anatase TiO2 surface. We have calculated the migration energy barrier of water molecules, the vibrational prefactor through the phonon density of states, and the hopping rate along two principal directions. Lastly, in a kinetic Monte Carlo context, we have simulated and clarified the dynamical processes that are on the basis of the observed experimental behavior.

  • 20.
    Garcia-Bennett, Alfonso E.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Konig, Niclas
    Abrahamsson, Ninnie
    Kozhevnikova, Mariya
    Zhou, Chunfang
    Trolle, Carl
    Pankratova, Stanislava
    Berezin, Vladimir
    Kozlova, Elena N.
    In vitro generation of motor neuron precursors from mouse embryonic stem cells using mesoporous nanoparticles2014In: Nanomedicine, ISSN 1743-5889, E-ISSN 1748-6963, Vol. 9, no 16, 2457-2466 p.Article in journal (Refereed)
    Abstract [en]

    Aim: Stem cell-derived motor neurons (MNs) are utilized to develop replacement strategies for spinal cord disorders. Differentiation of embryonic stem cells into MN precursors involves factors and their repeated administration. We investigated if delivery of factors loaded into mesoporous nanoparticles could be effective for stem cell differentiation in vitro. Materials & methods: We used a mouse embryonic stem cell line expressing green fluorescent protein under the promoter for the MN-specific gene Hb9 to visualize the level of MN differentiation. The differentiation of stem cells was evaluated by expression of MN-specific transcription factors monitored by quantitative real-time PCR reactions and immunocytochemistry. Results: Mesoporous nanoparticles have strong affiliation to the embryoid bodies, penetrate inside the embryoid bodies and come in contact with differentiating cells. Conclusion: Repeated administration of soluble factors into a culture medium can be avoided due to a sustained release effect using mesoporous silica.

  • 21.
    Gebauer, Denis
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Oliynyk, Vitaliy
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Salajkova, Michaela
    Sort, Jordi
    Zhou, Qi
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Salazar-Alvarez, German
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A transparent hybrid of nanocrystalline cellulose and amorphous calcium carbonate nanoparticles2011In: NANOSCALE, ISSN 2040-3364, Vol. 3, no 9, 3563-3566 p.Article in journal (Refereed)
    Abstract [en]

    Nanocellulose hybrids are promising candidates for biodegradable multifunctional materials. Hybrids of nanocrystalline cellulose (NCC) and amorphous calcium carbonate (ACC) nanoparticles were obtained through a facile chemical approach over a wide range of compositions. Controlling the interactions between NCC and ACC results in hard, transparent structures with tunable composition, homogeneity and anisotropy.

  • 22. Gómez de la Torre, Teresa Zardán
    et al.
    Herthnek, David
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab). Uppsala University, Sweden.
    Strømme, Maria
    A Magnetic Nanobead-Based Read-Out Procedure for Rapid Detection of DNA Molecules2017In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 17, no 4, 2861-2864 p.Article in journal (Refereed)
    Abstract [en]

    The presented measurement and data analysis procedure reduces the read-out time for the volumeamplified magnetic nanobead detection assay from similar to 30 min to only 2 min, providing fast, sensitive detection of DNA molecules. The molecular detection and amplification protocol was verified using samples containing rolling circle-amplified DNA products formed from synthetic Vibrio cholerae target DNA, with a limit of detection of 5 pM. The developed read-out method could be used to rapidly identify pathogens in a variety of applications including target screening in hospitals with limited resources, in out-patient settings and in the field.

  • 23. Harada, Y.
    et al.
    Miyawaki, J.
    Niwa, H.
    Yamazoe, K.
    Pettersson, Lars G. M.
    Stockholm University, Faculty of Science, Department of Physics.
    Nilsson, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Probing the OH Stretch in Different Local Environments in Liquid Water2017In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 8, no 22, 5487-5491 p.Article in journal (Refereed)
    Abstract [en]

    We use resonant inelastic X-ray scattering (RIXS) to resolve vibrational losses corresponding to the OH stretch where the X-ray absorption process allows us to selectively probe different structural subensembles in liquid water. The results point to a unified interpretation of X-ray and vibrational spectroscopic data in line with a picture of two classes of structural environments in the liquid at ambient conditions with predominantly close-packed high-density liquid (HDL) and occasional local fluctuations into strongly tetrahedral low-density liquid (LDL).

  • 24.
    Hu, Jianfeng
    et al.
    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).
    Intragranular heterojunctions formed by ordered coalescence of strontium and barium titanate nanocrystals2015In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 107, 14-17 p.Article in journal (Refereed)
    Abstract [en]

    Crystal growth by nanocrystal-assembly plays an important role in the synthesis and preparation of nanostructural materials. In most cases, this crystal-growth mechanism is reported to occur in unary nanocrystal systems and in solution environment. Here, we report a new observation of grain growth by ordered coalescence of nanocrystals occurring in SrTiO3-BaTiO3 binary system during solid-state sintering, which also results in unique oxide heterostructures inside coarsened grains in bulk polycrystalline materials.

  • 25.
    Hu, Jianfeng
    et al.
    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).
    Ordered coalescence of nano crystallites contributing to the rapid anisotropic grain growth in silicon nitride ceramics2013In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 69, no 3, 270-273 p.Article in journal (Refereed)
    Abstract [en]

    Microstructural characterization is performed on two dense Si3N4 ceramic samples consolidated by spark plasma sintering (SPS): one fabricated using alpha-Si3N4 and the other using beta-Si3N4 as the starting powder. A novel mechanism is revealed where ordered coalescence of nano beta-crystallites accelerate the rapid beta-Si3N4 anisotropic grain growth. The rapid alpha- to beta-Si3N4 phase transformation via a high supersaturation of dissolved Si3N4 in the melt favors this mechanism. The high heating rate by SPS is essential for achieving such supersaturation.

  • 26.
    Jaworski, Aleksander
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    The Bearings from Rare-Earth (RE = La, Lu, Sc, Y) Cations on the Oxygen Environments in Aluminosilicate Glasses: A Study by Solid State O-17 NMR, Molecular Dynamics Simulations, and DFT Calculations2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 24, 13181-13198 p.Article in journal (Refereed)
    Abstract [en]

    Aluminosilicate (AS) glasses incorporating trivalent cations of rare-earth (RE) elements exhibit a significant structural disorder and manifest building blocks incommensurate with conventional glass structure models. We present a comprehensive experimental and computational study of the O speciations in RE2O3-Al2O3-SiO2 glasses with RE = {La3+, Y3+, Lu3+, Sc3+}, where the cations are ordered according to increasing field-strength. The coexisting O-17([p])-Sip-mAlm moieties were quantified by magic-angle-spinning (MAS) O-17 nuclear magnetic resonance (NMR) experiments and atomistic molecular dynamics (MD) simulations. Experimental O-17 quadrupolar products ((C) over bar (Qn)) and isotropic chemical shifts ((delta) over bar (iso)) agreed well with predictions from density functional theory with the projector augmented wave (PAW) and gauge including PAW approaches, respectively. We highlight an observed strong influence of both {(delta) over bar (iso), (C) over bar (Qn)} NMR parameters on the average number of O-17([p])-RE3+ contacts ((q) over bar) and establish simple correlations between g and each of Sisc, and CQ, that encompass mA.1, moieties with 1 < p < 3. The quadrupolar product of each O-[p]-Sip-mAlm motif depends linearly on the all fractional ionicity of,the bonds to the 170 site, which is readily calculated from the parameter set {m, p, (q) over bar} with (q) over bar extracted from the MD-generated glass models. We rationalize and discuss the stability of each O[p]-Sip-mAlm moiety using bond valence sums evaluated on the MD-derived RE AS glass models: all comprise non-negligible populations of unconventional 0 species, such as free O2- ions (O-[0] coordinations), and oxygen triclusters (O-[3]-SiAl2 and O-[3]-Al-3). The triclusters preferentially connect high-coordination Al-[5]/Al-[6] species via edge-sharing, where the participation in corner or edge shared polyhedra is reflected in the {(delta) over bar (iso), (C) over bar (Qn)} O-17 NMR parameters.

  • 27.
    Keshavarzi, Neda
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Rad, Farshid Mashayekhy
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Mace, Amber
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ansari, Farhan
    Akhtar, Farid
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Berglund, Lars
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nanocellulose-Zeolite Composite Films for Odor Elimination2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 26, 14254-14262 p.Article in journal (Refereed)
    Abstract [en]

    Free standing and strong odor-removing composite films of cellulose nanofibrils (CNF) with a high content of nanoporous zeolite adsorbents have been colloidally processed. Thermogravimetric desorption analysis (TGA) and infrared spectroscopy combined with computational simulations showed that commercially available silicalite-1 and ZSM-5 have a high affinity and uptake of volatile odors like ethanethiol and propanethiol, also in the presence of water. The simulations showed that propanethiol has a higher affinity, up to 16%, to the two zeolites compared with ethanethiol. Highly flexible and strong free-standing zeolite CNF films with an adsorbent loading of 89 w/w% have been produced by Ca-induced gelation and vacuum filtration. The CNF-network controls the strength of the composite films and 100 mu m thick zeolite CNF films with a CNF content of less than 10 vol % displayed a tensile strength approaching 10 MPa. Headspace solid phase microextraction (SPME) coupled to gas chromatography mass spectroscopy (GC/MS) analysis showed that the CNF zeolite films can eliminate the volatile thiol-based odors to concentrations below the detection ability of the human olfactory system. Odor removing zeolite-cellulose nanofibril films could enable improved transport and storage of fruits and vegetables rich in odors, for example, onion and the tasty but foul-smelling South-East Asian Durian fruit.

  • 28. Krüger, Martin
    et al.
    Reinsch, Helge
    Inge, Andrew Kentaro
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Stock, Norbert
    Effect of partial linker fluorination and linker extension on structure and properties of the Al-MOF CAU-102017In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 249, 128-136 p.Article in journal (Refereed)
    Abstract [en]

    The systematic investigation of the solvothermal system Al3+/5-fluoroisophthalic acid (H(2)mBDC-5F)/isophthalic acid (H(2)mBDC)/DMF/H2O through a mixed-linker approach led to new mixed-linker CAU-10 derivatives containing 11, 28 and 44% of fluorinated linker molecules (denoted as CAU-10-H/F-11, CAU-10-H/F-28 and CAU-10-H/F-44, respectively), as determined by NMR spectroscopy. The crystal structure of CAU-10-H/F-28 was determined using the Rietveld method (space group 14(1)md, a = b = 21.3075(5), c = 10.7101(3) angstrom). The structure is built up by helical chains composed of cis corner-sharing AlO6 polyhedra. Each of these helices is interconnected to four adjacent helices with alternating rotational orientation through the carboxylate groups of mBDC(2-) linker molecules. Thus, accessible, square-shaped channels are formed. Sorption measurements revealed a high dependency of the adsorbed amount of gas on the degree of fluorination. With increasing fluorination, the total uptake decreases in N-2, H-2 and H2O sorption experiments and the hydrophobic character of the pores increases. In addition, an extended CAU-10 derivative, CAU-10-HTATB, was discovered using the tricarboxylic acid 4,4',4-s-triazine-2,4,6-triyl-tribenzoic acid (H(3)TATB) during the high-throughput investigation of the system Al3+/H(3)TATB/DMF/H2O. This new MOF, which was denoted CAU-10-HTATB, was thoroughly characterized using IR spectroscopy, thermogravimetric and elemental analysis, temperature dependent powder X-ray diffraction (PXRD) and sorption measurements. Although the compound is thermally stable up to 400 degrees C according to temperature-dependent PXRD measurements, it is not porous towards N2 molecules. The structure of CAU-10-HTATB could be also refined from PXRD data using the Rietveld method (space group l4(1)/a, a = b = 36.438 (1), c = 10.9373 (9) angstrom).

  • 29. Kupferschmidt, Natalia
    et al.
    Qazi, Khaleda Rahman
    Kemi, Cecilia
    Vallhov, Helen
    Garcia-Bennett, Alfonso E.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gabrielsson, Susanne
    Scheynius, Annika
    Mesoporous silica particles potentiate antigen-specific T-cell responses2014In: Nanomedicine, ISSN 1743-5889, E-ISSN 1748-6963, Vol. 9, no 12, 1835-1846 p.Article in journal (Refereed)
    Abstract [en]

    Aim: To study the adjuvant effect of mesoporous silica particles and their capability of modifying an already existing allergic Th2-like immune response. Materials & methods: The adjuvant effect of Santa Barbara Amorphous-15 (SBA-15) mesoporous silica particles was studied in an antigen-specific ovalbumin (OVA) system in vitro and in vivo. The capacity of the OVA-loaded SBA-15 particles (SBA-15-OVA) to modify an existing immune response was assessed in a murine allergy model. Results: SBA-15-OVA induced significantly stronger OVA-specific splenocyte proliferation compared with OVA alone. Significantly higher IFN-gamma production was observed in ex vivo OVA-stimulated splenocytes from SBA-15-OVA-immunized mice compared with mice injected with only SBA-15 or OVA. Treatment of OVA-sensitized mice with SBA-15-OVA modified the immune response with significantly lower serum levels of OVA-specific IgE and higher IgG levels compared with the alum-OVA-treated group. Conclusion: The results are promising for the continued development of mesoporous silica materials for therapeutic applications.

  • 30. Kupferschmidt, Natalia
    et al.
    Xia, Xin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Labrador, Roberto H.
    Atluri, Rambabu
    Ballell, Lluis
    Garcia-Bennett, Alfonso E.
    In vivo oral toxicological evaluation of mesoporous silica particles2013In: Nanomedicine, ISSN 1743-5889, E-ISSN 1748-6963, Vol. 8, no 1, 57-64 p.Article in journal (Refereed)
    Abstract [en]

    Background: Mesoporous silica particles are highly promising nanomaterials for biomedical applications. They can be used to improve bioavailability, solubility and drug stability and to protect drugs from the acidic conditions of the stomach, leading to increased drug effectiveness. Their biocompatibility in vivo has recieved little attention, in particular regarding oral administration. Aim: To study the oral tolerance of micron-sized nanoporous folic acid-templated material-1 (cylindrical, 2D hexagonal pore structure) and nanometer-sized anionic-surfactant-templated mesoporous silica material-6 (cylindrical, 3D cubic pore structure) mesoporous silica particles in Sprague Dawley rats. Materials & methods: A dose stepwise procedure or range finding test was followed by a consequent confirmatory test. The confirmatory test included daily administrations of 2000 and 1200 mg/kg doses for nanoporous folic acid-templated material-1 and anionic-surfactant-templated mesoporous silica material-6, respectively. Results: The maximum tolerated dose for anionic-surfactant-templated mesoporous silica material-6 was not reached. Similar results were observed for nanometer-sized anionic-surfactant-templated mesoporous silica material-1 in most of the animals, although adverse effects were observed in some animals that are most probably due to the administration by oral gavage of the formulated particles. Conclusion: The results are promising for the use of mesoporous silica materials as drug-delivery systems in oral administration.

  • 31. Kuruvilla, J.
    et al.
    Farinha, A. P.
    Bayat, Narges
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Cristobal, S.
    Surface proteomics on nanoparticles: a step to simplify the rapid prototyping of nanoparticles2017In: Nanoscale Horizons, ISSN 2055-6756, Vol. 2, no 1, 55-64 p.Article in journal (Refereed)
    Abstract [en]

    Engineered nanoparticles for biomedical applications require increasing effectiveness in targeting specific cells while preserving non-target cells' safety. We developed a surface proteomics method for a rapid and systematic analysis of the interphase between the nanoparticle protein corona and the targeted cells that could implement the rapid prototyping of nanomedicines. Native nanoparticles entering in a protein-rich liquid medium quickly form a macromolecular structure called protein corona. This protein structure defines the physical interaction between nanoparticles and target cells. The surface proteins compose the first line of interaction between this macromolecular structure and the cell surface of a target cell. We demonstrated that SUSTU (SUrface proteomics, Safety, Targeting, Uptake) provides a qualitative and quantitative analysis from the protein corona surface. With SUSTU, the spatial dynamics of the protein corona surface can be studied. Data from SUSTU would ascertain the nanoparticle functionalized groups exposed at a destiny that could circumvent preliminary in vitro experiments. Therefore, this methodcould implement in the analysis of nanoparticle targeting and uptakecapability andcouldbe integrated intoa rapidprototyping strategy which is a major challenge in nanomaterials science. Data are available via ProteomeXchange with the identifier PXD004636.

  • 32. Laksmono, Hartawan
    et al.
    McQueen, Trevor A.
    Sellberg, Jonas A.
    Stockholm University, Faculty of Science, Department of Physics. SLAC National Accelerator Laboratory, USA.
    Loh, N. Duane
    Huang, Congcong
    Schlesinger, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Sierra, Raymond G.
    Hampton, Christina Y.
    Nordlund, Dennis
    Beye, Martin
    Martin, Andrew V.
    Barty, Anton
    Seibert, M. Marvin
    Messerschmidt, Marc
    Williams, Garth J.
    Boutet, Sebastien
    Arnann-Winkel, Katrin
    Stockholm University, Faculty of Science, Department of Physics. University of Innsbruck, Austria.
    Loerting, Thomas
    Pettersson, Lars G. M.
    Stockholm University, Faculty of Science, Department of Physics.
    Bogan, Michael J.
    Nilsson, Anders
    Stockholm University, Faculty of Science, Department of Physics. SLAC National Accelerator Laboratory, USA; .
    Anomalous Behavior of the Homogeneous Ice Nucleation Rate in No-Man's Land2015In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 6, no 14, 2826-2832 p.Article in journal (Refereed)
    Abstract [en]

    We present an analysis of ice nucleation kinetics from near-ambient pressure water as temperature decreases below the homogeneous limit T-H by cooling micrometer-sized droplets (microdroplets) evaporatively at 10(3)-10(4) K/s and probing the structure ultrafast using femtosecond pulses from the Linac Coherent Light Source (LCLS) free-electron X-ray laser. Below 232 K, we observed a slower nucleation rate increase with decreasing temperature than anticipated from previous measurements, which we suggest is due to the rapid decrease in water's diffusivity. This is consistent with earlier findings that microdroplets do not crystallize at <227 K, but vitrify at cooling rates of 10(6)-10(7) K/s. We also hypothesize that the slower increase in the nucleation rate is connected with the proposed fragile-to-strong transition anomaly in water.

  • 33.
    LaRue, Jerry
    et al.
    Stockholm University, Faculty of Science, Department of Physics. SLAC National Accelerator Laboratory, USA; Chapman University, USA; Fritz-Haber Institute of the Max-Planck-Society, Germany.
    Krejčí, O.
    Stockholm University, Faculty of Science, Department of Physics. Charles University in Prague, Czech Republic; Institute of Physics of the Czech Academy of Sciences, Czech Republic.
    Yu, L.
    Beye, M.
    Ng, M. L.
    Öberg, H.
    Stockholm University, Faculty of Science, Department of Physics.
    Xin, H.
    Mercurio, G.
    Moeller, S.
    Turner, J. J.
    Nordlund, D.
    Coffee, R.
    Minitti, M. P.
    Wurth, W.
    Pettersson, Lars G. M.
    Stockholm University, Faculty of Science, Department of Physics.
    Öström, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Nilsson, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Abild-Pedersen, F.
    Ogasawara, H.
    Real-Time Elucidation of Catalytic Pathways in CO Hydrogenation on Ru2017In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 8, no 16, 3820-3825 p.Article in journal (Refereed)
    Abstract [en]

    The direct elucidation of the reaction pathways in heterogeneous catalysis has been challenging due to the short-lived nature of reaction intermediates. Here, we directly measured on ultrafast time scales the initial hydrogenation steps of adsorbed CO on a Ru catalyst surface, which is known as the bottleneck reaction in syngas and CO2 reforming processes. We initiated the hydrogenation of CO with an ultrafast laser temperature jump and probed transient changes in the electronic structure using real-time X-ray spectroscopy. In combination with theoretical simulations, we verified the formation of CHO during CO hydrogenation.

  • 34. Li, Xin
    et al.
    Leck, Caroline
    Stockholm University, Faculty of Science, Department of Meteorology .
    Sun, Lu
    Hede, Thomas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Tu, Yaoquan
    Ågren, Hans
    Cross-Linked Polysaccharide Assemblies in Marine Gels: An Atomistic Simulation2013In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 4, no 16, 2637-2642 p.Article in journal (Refereed)
    Abstract [en]

    Marine polymeric gels or colloidal nano- and microgels have been shown to contribute significantly to the primary marine aerosol and cloud condensation nuclei over remote marine areas. A microscopic understanding of such biologically derived matter at the sea air interface is important for future development of global climate models, but unfortunately cannot be obtained from modern characterization techniques. In this contribution, we employ molecular dynamics simulations to reveal the atomistic details of marine polymeric gels represented by anionic polysaccharide assemblies. The ionic bonds formed between polysaccharides and metal ions in seawater as well as the hydrophobic contribution to surface area are investigated in detail, and destabilization of the assemblies upon removal of Ca2+ or acidification is explained. These results provide insight into physicochemical properties of polysaccharide-Ca2+ structures and enable future studies of their roles of in the wetting process of cloud droplet activation.

  • 35.
    Li, Yunxiang
    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).
    Gao, Feifei
    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 pure-silica IZM-22017In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 237, 222-227 p.Article in journal (Refereed)
    Abstract [en]

    Pure-silica IZM-2 was synthesized for the first time, and the concentration of sodium hydroxide used during synthesis affected the phase purity and size of crystals. Most of the micropores in calcined pure silica IZM-2 that was synthesized in the presence of high concentrations of sodium hydroxide were inaccessible to N-2 adsorption; however, the micropores could be rendered accessible by applying either of two different post-synthetic treatments. Pure-silica IZM-2 could also be synthesized without sodium ions using the hydroxide version of the template. In this case, the micropores were accessible to N-2 directly after calcination. The size of pure-silica IZM-2 crystals obtained increased with the concentration of sodium hydroxide, with the highest concentrations giving spherical and micrometer-sized aggregates of pure-silica IZM-2 that consisted of intergrown particles (60-500 nm). The nature of the defects in pure-silica IZM-2 was studied with a combination of H-1, and Si-29 solid-state NMR spectroscopy. As expected, direct-polarization Si-29 NMR spectroscopy showed that the number of non-condensed silica groups decreased upon calcination. Calcined samples also showed broader Si-29 NMR bands for the fully condensed silica moieties, which indicated a broader distribution of bond angles and/or bond lengths. The siloxy and silanol groups in calcined pure-silica IZM-2 were accessible to protonation as determined by H-1 NMR spectroscopy. We could not determine the structure of pure-silica IZM-2 in its aggregated form; however, further studies of the synthetic conditions could yield larger, non-aggregated crystals that would facilitate structural determination.

  • 36.
    Li, Yunxiang
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zheng, Haoquan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yun, Yifeng
    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).
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gao, Feifei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    De-agglomeration of IZM-2 zeolite crystals by post-synthetic treatment2016In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 225, 185-191 p.Article in journal (Refereed)
    Abstract [en]

    Highly intergrown nanocrystals are commonly observed in zeolite samples, and the densely packed agglomerates may result in small secondary porosity, which restricts the advantage of hierarchical structures. In this work we take IZM-2 zeolite as an example to demonstrate a post-treatment method with diluted hydrofluoric acid solution, which de-agglomerates intergrown zeolite nanocrystals and improves the secondary porosity. The treated samples preserve high crystallinity, similar framework composition and distinctively higher external surface area compared to the agglomerated ones. The results show that this treatment is an effective method for de-agglomeration of intergrown nanocrystals without affecting the original framework.

  • 37. Liu, Ben
    et al.
    Yao, Huiqin
    Daniels, Robert A.
    Song, Wenqiao
    Zheng, Haoquan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Jin, Lei
    Suib, Steven L.
    He, Jie
    A facile synthesis of Fe3C@mesoporous carbon nitride nanospheres with superior electrocatalytic activity2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 10, 5441-5445 p.Article in journal (Refereed)
    Abstract [en]

    We report a colloidal amphiphile-templating approach to preparing nanosized Fe3C encapsulated within mesoporous nitrogen-doped carbon nanospheres (Fe3C@mCN). The obtained Fe3C@mCN hybrids having a high surface area and ultrafine Fe3C nanocrystals exhibited superior activity and durability for oxygen reduction.

  • 38.
    Liu, Chang
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Lourenco, Maicon P.
    Hedström, Svante
    Stockholm University, Faculty of Science, Department of Physics.
    Cavalca, Filippo
    Stockholm University, Faculty of Science, Department of Physics. SLAC National Accelerator Laboratory, United States.
    Diaz-Morales, Oscar
    Stockholm University, Faculty of Science, Department of Physics.
    Duarte, Hélio A.
    Nilsson, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Pettersson, Lars G. M.
    Stockholm University, Faculty of Science, Department of Physics.
    Stability and Effects of Subsurface Oxygen in Oxide-Derived Cu Catalyst for CO2 Reduction2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 45, 25010-25017 p.Article in journal (Refereed)
    Abstract [en]

    Oxide-derived copper (OD-Cu) catalysts are promising candidates for the electrochemical CO2 reduction reaction (CO2RR) due to the enhanced selectivity toward ethylene over methane evolution, which has been linked to the presence of subsurface oxygen (O-sb). In this work, O-sb is investigated with theoretical methods. Although O-sb is unstable in slab models, it becomes stabilized within a manually reduced OD-Cu nanocube model which was calculated by self-consistent charge density functional tight binding (SCC-DFTB). The results obtained with SCC-DFTB for the full nanocube were confirmed with subcluster models extracted from the nanocube, calculated with both density functional theory (DFT) and SCC-DFTB. The. higher stability of O-sb in the nanocube is attributed to the disordered structure and greater flexibility. The adsorption strength of CO on Cu(100) is enhanced by O-sb withdrawing electron density from the Cu atom, resulting in reduction of the sigma-repulsion. Hence, the coverage of CO may be increased, facilitating its dimerization.

  • 39. Lopes, Viviana R.
    et al.
    Loitto, Vesa
    Audinot, Jean-Nicolas
    Bayat, Narges
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gutleb, Arno C.
    Cristobal, Susana
    Dose-dependent autophagic effect of titanium dioxide nanoparticles in human HaCaT cells at non-cytotoxic levels2016In: Journal of Nanobiotechnology, ISSN 1477-3155, E-ISSN 1477-3155, Vol. 14, 22Article in journal (Refereed)
    Abstract [en]

    Background: Interactions between nanoparticles and cells are now the focus of a fast-growing area of research. Though many nanoparticles interact with cells without any acute toxic responses, metal oxide nanoparticles including those composed of titanium dioxide (TiO2-NPs) may disrupt the intracellular process of macroautophagy. Autophagy plays a key role in human health and disease, particularly in cancer and neurodegenerative diseases. We herein investigated the in vitro biological effects of TiO2-NPs (18 nm) on autophagy in human keratinocytes (HaCaT) cells at non-cytotoxic levels. Results: TiO2-NPs were characterized by transmission electron microscopy (TEM) and dynamic light scattering techniques. Cellular uptake, as evaluated by TEM and NanoSIMS revealed that NPs internalization led to the formation of autophagosomes. TiO2-NPs treatment did not reduce cell viability of HaCaT cells nor increased oxidative stress. Cellular autophagy was additionally evaluated by confocal microscopy using eGFP-LC3 keratinocytes, western blotting of autophagy marker LC3I/II, immunodetection of p62 and NBR1 proteins, and gene expression of LC3II, p62, NBR1, beclin1 and ATG5 by RT-qPCR. We also confirmed the formation and accumulation of autophagosomes in NPs treated cells with LC3-II upregulation. Based on the lack of degradation of p62 and NBR1 proteins, autophagosomes accumulation at a high dose (25.0 mu g/ml) is due to blockage while a low dose (0.16 mu g/ml) promoted autophagy. Cellular viability was not affected in either case. Conclusions: The uptake of TiO2-NPs led to a dose-dependent increase in autophagic effect under non-cytotoxic conditions. Our results suggest dose-dependent autophagic effect over time as a cellular response to TiO2-NPs. Most importantly, these findings suggest that simple toxicity data are not enough to understand the full impact of TiO2-NPs and their effects on cellular pathways or function.

  • 40. Maldonado, P.
    et al.
    Godinho, José
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Evins, L. Z.
    Oppeneeer, P. M.
    Ab Initio Prediction of Surface Stability of Fluorite Materials and Experimental Verification2013In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 13, 6639-6650 p.Article in journal (Refereed)
    Abstract [en]

    Utilizing first-principle simulations [based on density functional theory (DFT) corrected for on-site Coulomb interactions (DFT+U)], we develop a model to explain the experimental stability in solution of materials having the fluorite structure, such as CaF2 and CeO2. It is shown that the stability of a surface is mainly dependent on its atomic structure and the presence of sites where atoms are deficiently bonded. Using as reference planes the surfaces with low surface formation energies, viz., (111), (100), and (110), our results reveal the relation between the surface energy of any Miller-indexed plane and the surface energy of those reference planes, being dependent on the fluorite surface structure only. Therefore, they follow the same trend for CaF2 and CeO2. Comparison with experimental results shows a correlation between the trends of dry surface energies and surface stabilities during dissolution of both CaF2 and CeO2, even though the chemical processes of dissolution of CeO2 and CaF2 are different. A deviation between ab initio predictions and experiments for some surfaces highlights the sensitivity of the developed model to the treatment of surface dipolar moments.

  • 41.
    Mayence, Arnaud
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wery, Madeleine
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wetterskog, Erik
    Svedlindh, Peter
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Interfacial strain and defects in asymmetric Fe-Mn oxide hybrid nanoparticles2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 29, 14171-14177 p.Article in journal (Refereed)
    Abstract [en]

    Asymmetric Fe-Mn oxide hybrid nanoparticles have been obtained by a seed-mediated thermal decomposition-based synthesis route. The use of benzyl ether as the solvent was found to promote the orientational growth of Mn1-xO onto the iron oxide nanocube seeds yielding mainly dimers and trimers whereas 1-octadecene yields large nanoparticles. HRTEM imaging and HAADF-STEM tomography performed on dimers show that the growth of Mn1-xO occurs preferentially along the edges of iron oxide nanocubes where both oxides share a common crystallographic orientation. Fourier filtering and geometric phase analysis of dimers reveal a lattice mismatch of 5% and a large interfacial strain together with a significant concentration of defects. The saturation magnetization is lower and the coercivity is higher for the Fe-Mn oxide hybrid nanoparticles compared to the iron oxide nanocube seeds.

  • 42. McFarland, Hannah L.
    et al.
    Ahmed, Towfiq
    Zhu, Jian-Xin
    Balatsky, Alexander V.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Los Alamos National Laboratory, New Mexico.
    Haradsen, Jason T.
    First-Principles Investigation of Nanopore Sequencing Using Variable Voltage Bias on Graphene-Based Nanoribbons2015In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 6, no 13, 2616-2621 p.Article in journal (Refereed)
    Abstract [en]

    In this study, we examine the mechanism of nanopore-based DNA sequencing using a voltage bias across a graphene nanoribbon. Using density function theory and a nonequilibrium Green's function approach, we determine the transmission spectra and current profile for adenine, guanine, cytosine, thymine, and uracil as a function of bias voltage in an energy minimized configuration. Utilizing the transmission current, we provide a general methodology for the development of a three nanopore graphene-based device that can be used to distinguish between the various nucleobases for DNA/RNA sequencing. From our analysis, we deduce that it is possible to use different transverse currents across a multinanopore device to differentiate between nucleobases using various voltages of 0.5, 1.3, and 1.6 V. Overall, our goal is to improve nanopore design to further DNA/RNA nucleobase sequencing and biomolecule identification techniques.

  • 43.
    Mezger, Anja
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Fock, Jeppe
    Antunes, Paula
    Osterberg, Frederik W.
    Boisen, Anja
    Nilsson, Mats
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Hansen, Mikkel F.
    Ahlford, Annika
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Donolato, Marco
    Scalable DNA-Based Magnetic Nanoparticle Agglutination Assay for Bacterial Detection in Patient Samples2015In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 9, no 7, 7374-7382 p.Article in journal (Refereed)
    Abstract [en]

    We demonstrate a nanoparticle-based assay for the detection of bacteria causing urinary tract infections in patient samples with a total assay time of 4 h. This time is significantly shorter than the current gold standard, plate culture, which can take several days depending on the pathogen. The assay is based on padlock probe recognition followed by two cycles of rolling circle amplification (RCA) to form DNA coils corresponding to the target bacterial DNA. The readout of the RCA products is based on optomagnetic measurements of the specific agglutination of DNA-bound magnetic nanoparticles (MNPs) using low-cost optoelectronic components from Blu-ray drives. We implement a detection approach, which relies on the monomerization of the RCA products, the use of the monomers to link and agglutinate two populations of MNPs functionalized with universal nontarget specific detection probes and on the introduction of a magnetic incubation scheme. This enables multiplex detection of Escherichia coli, Proteus mirabilis and Pseudomonas aeruginosa at clinically relevant concentrations, demonstrating a factor of 30 improvement in sensitivity compared to previous MNP-based detection schemes. Thanks to the universal probes, the same set of functionalized MNPs can be used to read out products from a multitude of RCA targets, making the approach truly scalable for parallel detection of multiple bacteria in a future integrated point of care molecular diagnostics system.

  • 44. Moskalenko, Sveatoslav A.
    et al.
    Podlesny, Igor V.
    Dumanov, Evgheni V.
    Liberman, Michael A.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Novikov, Boris V.
    Dispersion laws of the two-dimensional cavity magnetoexciton-polaritons2016In: Journal of Nanophotonics, ISSN 1934-2608, Vol. 10, no 3, 036006Article in journal (Refereed)
    Abstract [en]

    The energy spectrum of the two-dimensional cavity magnetoexciton-polaritons has been investigated previously, using exact solutions for the Landau quantization (LQ) of conduction electrons and heavy holes (hhs) provided by the Rashba method. Two lowest LQ levels for electrons and three lowest Landau levels for hhs lead to the construction of the six lowest magnetoexciton sates. They consist of two dipole-active, two quadrupole-active, and the two forbidden quantum transitions from the ground state of the crystal to the magnetoexciton states. The interaction of the four optical-active magnetoexciton states with the cavity-mode photons with a given circular polarization and with well-defined incidence direction leads to the creation of five magnetoexciton-polariton branches. The fifth-order dispersion equation is examined by using numerical calculations and the second-order dispersion equation is solved analytically, taking into account only one dipole-active magnetoexciton state in the point of the in-plane wave vector (k) over right arrow || = 0. The effective polariton mass on the lower polariton branch, the Rabi frequency, and the corresponding Hopfield coefficients are determined in dependence on the magnetic-field strength, the Rashba spin-orbit coupling parameters, and the electron and hole g-factors. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE).

  • 45.
    Ojuva, Arto
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Akhtar, Farid
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Tomsia, Antoni P.
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Laminated Adsorbents with Very Rapid CO2 Uptake by Freeze-Casting of Zeolites2013In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, no 7, 2669-2676 p.Article in journal (Refereed)
    Abstract [en]

    Structured zeolite 13X monoliths with a laminated structure and hierarchical macro-/microporosity were prepared by freeze-casting aqueous suspensions of zeolite 13X powder, bentonite, and polyethylene glycol. Colloidally stable suspensions with a low viscosity at both room temperature and near freezing could be prepared at alkaline conditions where both the zeolite 13X powder and bentonite carry a negative surface charge. Slow directional freezing of the suspensions led to the formation of well-defined and thin lamellar pores and pore walls while fast freezing resulted in more cylindrical pores. The wall thickness, which varied between 8 and 35 mu m, increased with increasing solids loading of the suspension. Thermal treatment at 1053 K of the freeze-cast bodies containing between 9 and 17 wt % bentonite resulted in mechanically stable zeolite 13X monoliths. The monoliths displayed a carbon dioxide uptake capacity of 4-5 mmol/g and an uptake kinetics characterized by a very fast initial uptake where more than 50% of the maximum uptake was reached within 15 s. Freeze-cast laminated zeolite monoliths could be used to improve the volumetric efficiency and reduce the cycle time, of importance in, for example, biogas upgrading and CO2 separation from flue gas.

  • 46. Philippe, Bertrand
    et al.
    Jacobsson, T. Jesper
    Correa-Baena, Juan-Pablo
    Jena, Naresh K.
    Banerjee, Amitava
    Chakraborty, Sudip
    Cappel, Ute B.
    Ahuja, Rajeev
    Hagfeldt, Anders
    Odelius, Michael
    Stockholm University, Faculty of Science, Department of Physics.
    Rensmo, Håkan
    Valence Level Character in a Mixed Perovskite Material and Determination of the Valence Band Maximum from Photoelectron Spectroscopy: Variation with Photon Energy2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 48, 26655-26666 p.Article in journal (Refereed)
    Abstract [en]

    A better understanding of the electronic structure of perovskite materials used in photovoltaic devices is essential for their development and optimization. In this investigation, synchrotron-based photoelectron spectroscopy (PES) was used to experimentally delineate the character and energy position of the valence band structures of a mixed perovskite. The valence band was measured using PES with photon energies ranging from ultraviolet photoelectron spectroscopy (21.2 eV) to hard X-rays (up to 4000 eV), and by taking the variation of the photoionization cross sections into account, we could experimentally determine the inorganic and organic contributions. The experiments were compared to theoretical calculations to further distinguish the role of the different anions in the electronic structure. This work also includes a thorough study of the valence band maximum and its position in relation to the Fermi level, which is crucial for the design and optimization of complete solar cells and their functional properties.

  • 47. Rehnlund, David
    et al.
    Valvo, Mario
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ångström, Jonas
    Sahlberg, Martin
    Edström, Kristina
    Nyholm, Leif
    Electrochemical fabrication and characterization of Cu/Cu2O multi-layered micro and nanorods in Li-ion batteries2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 32, 13591-13604 p.Article in journal (Refereed)
    Abstract [en]

    Electrodes composed of freestanding nano- and microrods composed of stacked layers of copper and cuprous oxide have been fabricated using a straightforward one-step template-assisted pulsed galvanostatic electrodeposition approach. The approach provided precise control of the thickness of each individual layer of the high-aspect-ratio rods as was verified by SEM, EDS, XRD, TEM and EELS measurements. Rods with diameters of 80, 200 and 1000 nm were deposited and the influence of the template pore size on the structure and electrochemical performance of the conversion reaction based electrodes in lithium-ion batteries was investigated. The multi-layered Cu2O/Cu nano-and microrod electrodes exhibited a potential window of more than 2 V, which was ascribed to the presence of a distribution of Cu2O (and Cu, respectively) nanoparticles with different sizes and redox potentials. As approximately the same areal capacity was obtained independent of the diameter of the multi-layered rods the results demonstrate the presence of an electroactive Cu2O layer with a thickness defined by the time domain of the measurements. It is also demonstrated that while the areal capacity of the electrodes decreased dramatically when the scan rate was increased from 0.1 to 2 mV s(-1), the capacity remained practically constant when the scan rate was further increased to 100 mV s(-1). This behaviour can be explained by assuming that the capacity is limited by the lithium ion diffusion rate though the Cu2O layer generated during the oxidation step. The electrochemical performance of present type of 3-D multi-layered rods provides new insights into the lithiation and delithiation reactions taking place for conversion reaction materials such as Cu2O.

  • 48. Renman, Viktor
    et al.
    Valvo, Mario
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zimmermann, Iwan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gomez, Cesar Pay
    Edström, Kristina
    Investigation of the Structural and Electrochemical Properties of Mn2Sb3O6CI upon Reaction with Li Ions2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 11, 5949-5958 p.Article in journal (Refereed)
    Abstract [en]

    The structural and electrochemical properties of a quaternary layered compound with elemental composition Mn2Sb3O6Cl have been investigated upon reaction with lithium in Li half cells. Operando XRD was used to investigate the potential impact of this particular layered structure on the lithiation process. Although the results suggest that the material is primarily reacted through a conventional conversion mechanism, they also provide some hints that the space between the slabs may act as preferential entry points for lithium ions but not for the larger sodium ions. Cyclic voltammetry, galvanostatic cycling, HRTEM, SAED, and EELS analyses were performed to unravel the details of the reaction mechanism with the lithium ions. It is found that two pairs of reactions are mainly responsible for the reversible electrochemical cycling of this compound, namely, the alloying of Li-Sb and the conversion of MnxOy to metallic Mn with concomitant formation of Li2O upon lithium uptake. A moderate cycling stability is achieved with a gravimetric capacity of 467 mAh g(-1) after 100 cycles between 0.05 and 2.2 V vs Li+/Li despite the large particle sizes of the active material and its nonoptimal inclusion into composite coatings. The electrochemical activity of the title compound was also tested in Na half cells between 0.05 and 2 V vs Ne/Na. It was found that a prolonged period of electrochemical milling is required to fully gain access to the active material, after which the cell delivers a capacity of 350 mAh CI. These factors are demonstrated to clearly limit the ultimate performances for these electrodes.

  • 49. Russell, Camilla
    et al.
    Welch, Ken
    Jarvius, Jonas
    Cai, Yixiao
    Brucas, Rimantas
    Nikolajeff, Fredrik
    Svedlindh, Peter
    Nilsson, Mats
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab). Uppsala University, Sweden.
    Gold Nanowire Based Electrical DNA Detection Using Rolling Circle Amplification2014In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 8, no 2, 1147-1153 p.Article in journal (Refereed)
    Abstract [en]

    We present an electrical sensor that uses rolling circle amplification (RCA) of DNA to stretch across the gap between two electrodes, interact with metal nanoparticle seeds to generate an electrically conductive nanowire, and produce electrical signals upon detection of specific target DNA sequences. RCA is a highly specific molecular detection mechanism based on DNA probe circularization. With this technique, long single-stranded DNA with simple repetitive sequences are produced. Here we show that stretched RCA products can be metalized using silver or gold solutions to form metal wires. Upon metallization, the resistance drops from T Omega to k Omega for silver and to Omega for gold. Metallization is seeded by gold nanoparticles aligned along the single-stranded DNA product through hybridization of functionalized oligonucleotides. We show that combining RCA with electrical DNA detection produces results in readout with very high signal-to-noise ratio, an essential feature for sensitive and specific detection assays. Finally, we demonstrate detection of 10 ng of Escherichia coli genomic DNA using the sensor concept.

  • 50.
    Salamon, David
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Maca, Karel
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Rapid sintering of crack free zirconia ceramics by pressure less spark plasma sintering2012In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 66, no 11, 899-902 p.Article in journal (Refereed)
    Abstract [en]

    Heating of a ceramic green body is a key step in sintering. We have created inside a spark plasma sintering apparatus pressure-less sintering conditions that allow homogeneous and extremely rapid heating. Dense and crack-free zirconia ceramic was sintered at heating rates of up to 500 degrees C min(-1) and dwell times of 2 min. This extremely fast sintering process is accompanied by extremely rapid grain growth, indicating a non classical sintering mechanism. No grain size gradients were observed inside the sintered zirconia ceramics.

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