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  • 51.
    Fornara, Andrea
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Chiavarino, Annalisa
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    PLGA-PEG multifunctional nanoparticles for simultaneous drug delivery and imaging by MRI and fluorescence microscopy2012Ingår i: Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2012, 2012, s. 4-7Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work deals with the synthesis of multifunctional nanoparticles based on biocompatible di-block copolymer (PLGA-PEG) via an emulsion-evaporation method. To enable their visualization, these nanoparticles can be loaded with iron oxide nanoparticles for Magnetic Resonance Imaging (MRI) and/or quantum dots for fluorescent microscopy. A therapeutic agent, Indomethacin, can also be loaded and released. The influence of synthesis parameters on nanoparticle size (in the range 70-150 nm) has been controlled to achieve specific cellular interactions avoiding possible immuno-response. These multifunctional nanoparticles possess excellent photoemission properties for fluorescent microscopy and enhanced contrast efficiency for T 2 MRI imaging compared to available agents used today. In-vitro experiments confirm the low cytotoxicity of such nanoparticles and their excellent visualization properties by MRI and fluorescence microscopy in cells and biological tissues.

  • 52.
    Fornara, Andrea
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Funktionella material, FNM (Stängd 20120101).
    Johansson, Petter
    Petersson, Karolina
    Gustafsson, Stefan
    Qin, Jian
    Olsson, Eva
    Ilver, Dag
    Krozer, Anatol
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Funktionella material, FNM (Stängd 20120101).
    Johansson, Christer
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Funktionella material, FNM (Stängd 20120101).
    Tailored Magnetic Nanoparticles for Direct and Sensitive Detection of Biomolecules in Biological Samples2008Ingår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 8, nr 10, s. 3423-3428Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We developed nanoparticles with tailored magnetic properties for sensitive detection of biomolecules directly in biological samples in a single step. Thermally blocked nanoparticles obtained by thermal hydrolysis are mixed with sample solutions and the variation of the magnetic relaxation due to surface binding is used to detect the presence of biomolecules. The binding events significantly increase the hydrodynamic volume of nanoparticles, thus changing their Brownian relaxation frequency which is measured by a specifically developed AC-susceptometer.

    The system was tested for the presence of Brucella antibodies in serum samples from infected cows and the surface of the nanoparticles was functionalized with lipopolysaccarides (LPS) from Brucella abortus. The hydrodynamic volume of functionalized particles increased by 25-35% as a result of the binding of the antibodies, as measured by changes in the susceptibility in an alternating magnetic field. The method has shown high sensitivity, with detection limit of 7 nmol·L-1 in serum without any pre-treatment of the biological samples.

    The detection method is very sensitive, cost-efficient and versatile, giving a direct indication if the animal is infected or not, making it suitable for point-of care applications. The functionalization of tailored magnetic nanoparticles can be modified to suit numerous homogenous assays for a wide range of applications.

  • 53.
    Fornara, Andrea
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Laurent, Sophie
    University of Mons.
    Muller, Robert
    University of Mons.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Bifunctional polylactide coated iron oxide nanoparticles for drug delivery and MRI contrast enhancementIngår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095Artikel i tidskrift (Övrigt vetenskapligt)
  • 54.
    Fornara, Andrea
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Recalenda, Alberto
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Sugunan, Abhilash
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Fei, Ye
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Laurent, Sophie
    University of Mons.
    Muller, Robert
    University of Mons.
    Zou, Jing
    University of Tampere.
    Usama, Abo-RAmadan
    University of Helsinki.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Polymeric/inorganic multifunctional nanoparticles for simultaneous drug delivery and visualization2010Ingår i: Materials Research Society Symposium Proceedings, ISSN 0272-9172, E-ISSN 1946-4274, Vol. 1257Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanoparticles consisting of different biocompatible materials are attracting a lot of interest in the biomedical area as useful tools for drug delivery, photo-therapy and contrast enhancement agents in MRI, fluorescence and confocal microscopy. This work mainly focuses on the synthesis of polymeric/inorganic multifunctional nanoparticles (PIMN) based on biocompatible di-block copolymer poly(L,L-lactide-co-ethylene glycol) (PLLA-PEG) via an emulsion-evaporation method. Besides containing a hydrophobic drug (Indomethacin), these polymeric nanoparticles incorporate different visualization agents such as superparamagnetic iron oxide nanoparticles (SPION) and fluorescent Quantum Dots (QDs) that are used as contrast agents for Magnetic Resonance Imaging (MRI) and fluorescence microscopy together. Gold Nanorods are also incorporated in such nanostructures to allow simultaneous visualization and photodynamic therapy. MRI studies are performed with different loading of SPION into PIMN, showing an enhancement in T2 contrast superior to commercial contrast agents. Core-shell QDs absorption and emission spectra are recorded before and after their loading into PIMN. With these polymeric/inorganic multifunctional nanoparticles, both MRI visualization and confocal fluorescence microscopy studies can be performed. Gold nanorods are also synthesized and incorporated into PIMN without changing their longitudinal absorption peak usable for lased excitation and phototherapy. In-vitro cytotoxicity studies have also been performed to confirm the low cytotoxicity of PIMN for further in-vivo studies.

  • 55.
    Fornara, Andrea
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Vogt, Carmen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Khartsev, Sergiy
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Li, Shanghua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Grishin, Alexander
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Synthesis, characterization and magneto-optical properties of transparent magnetic PMMA/nanoparticles compositeManuskript (preprint) (Övrigt vetenskapligt)
  • 56.
    Furberg, Richard
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Li, Shanghua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Palm, Björn E.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Use of a novel nano- and micro-porous structure for enhanced boiling in a plate heat exchanger2008Ingår i: Proceedings of the 9th IEA heat pump conference, Zürich, CH, Zürich, CH: Academic Conferences Publishing, 2008Konferensbidrag (Refereegranskat)
  • 57.
    Furberg, Richard
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Li, Shanghua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Dendritically ordered nano-particles in a micro-porous structure for enhanced boiling2006Ingår i: Proceedings of 13th International Heat Transfer Conference, NAN-07, 2006, Vol. NAN-07Konferensbidrag (Refereegranskat)
    Abstract [en]

    Presented research is an experimental study of the pool boiling performance of copper surfaces enhanced with a newly developed structure. The enhanced surfaces were fabricated with an electrodeposition method where metallic nano-particles are formed and dendritically connected into an ordered micro-porous structure. To further alter the grain size of the dendritic branches, some surfaces underwent an annealing treatment. The tests were conducted with the test objects horizontally oriented and submerged in a refrigerant: R134A, at saturated conditions and at an absolute pressure of 4 bar. The heat flux varied between 0.1 and 10 W/cm2. The boiling performance of the enhanced surfaces was found to be dependent on controllable surface characteristics such as thickness of the structure and the interconnectivity of the grains in the dendritic branches. Temperature differences less than 0.3 °C and 1.5 °C at heat fluxes of 1 and 10 W/cm2 respectively have been recorded, corresponding to heat transfer coefficients up to 7.6 Wcm-2K-1. The micro-porous structure has been shown to facilitate high performance boiling, which is attributed to its high porosity (∼94%), a dendritically formed and exceptionally large surface area, and to a high density of well suited vapor escape channels (50 – 470 per mm2).

  • 58.
    Furberg, Richard
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Palm, Björn E.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Li, Shanghua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    The Use of a Nano- and Microporous Surface Layer to Enhance Boiling in a Plate Heat Exchanger2009Ingår i: Journal of heat transfer, ISSN 0022-1481, E-ISSN 1528-8943, Vol. 131, nr 10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Presented research is an experimental study of the performance of a standard plate heat exchanger evaporator, both with and without a novel nano- and microporous copper structure, used to enhance the boiling heat transfer mechanism in the refrigerant channel. Various distance frames in the refrigerant channel were also employed to study the influence of the refrigerant mass flux on two-phase flow heat transfer. The tests were conducted at heat fluxes ranging between 4.5 kW/m(2) and 17 kW/m(2) with 134a as refrigerant. Pool boiling tests of the enhancement structure, under similar conditions and at various surface inclination angles, were also performed for reasons of comparison. The plate heat exchanger with the enhancement structure displayed up to ten times enhanced heat transfer coefficient in the refrigerant channel, resulting in an improvement in the overall heat transfer coefficient with over 100%. This significant boiling enhancement is in agreement with previous pool boiling experiments and confirms that the enhancement structure may be used to enhance the performance of plate heat exchangers. A simple superposition model was used to evaluate the results, and it was found that, primarily, the convective boiling mechanism was affected by the distance frames in the standard heat exchanger. On the other hand, with the enhanced boiling structure, variations in hydraulic diameter in the refrigerant channel caused a significant change in the nucleate boiling mechanism, which accounted for the largest effect on the heat transfer performance.

  • 59.
    Gunay, Merva
    et al.
    Fatih Univ, Istanbul, Turkey.
    Baykal, Abdulhadi
    Fatih Univ, Istanbul, Turkey.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Sozeri, Huseyin
    Natl Metrol Inst, Gebze, Turkey.
    A Green Chemical Synthesis and Characterization of Mn3O4 nanoparticles2012Ingår i: JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, ISSN 1557-1939, Vol. 25, nr 5, s. 1535-1539Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mn3O4 nanoparticles were synthesized via an ionic liquid (IL) assisted process at room temperature, which is rather difficult to achieve by other techniques. The synthesized product was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermal gravimetry (TG), and vibrating sample magnetometry (VSM). The prepared material showed a high purity, while crystallite size and particle size agree well with each other, 17 +/- 2 and 19 +/- 3 nm, respectively, revealing nearly single crystalline character of nanoparticles. The product contains 4 wt% of adsorbed water and ionic liquid. This method provides a facile, one-step, and low-cost route for the synthesis of nanostructures of metal oxides. In addition, [BMIM]BF4 could be collected and reused for subsequent reactions.

  • 60.
    Gustafsson, Stefan
    et al.
    Department of Applied Physics, Chalmers University of Technology.
    Fornara, Andrea
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Petersson, Karolina
    Imego AB.
    Johansson, Christer
    Imego AB.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Olsson, Eva
    Department of Applied Physics, Chalmers University of Technology.
    Evolution of Structural and Magnetic Properties of Magnetite Nanoparticles for Biomedical Applications2010Ingår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, nr 5, s. 2278-2284Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have investigated the evolution of microstructure and magnetic properties of thermally blocked magnetite nanoparticles, aimed for immunoassay applications, during their synthesis. High-resolution transmission electron microscopy (HRTEM) investigations of the size, size distribution, morphology, and crystal structure of particles reveal that particles at an early stage of the reaction process are either single crystals or polycrystals containing planar faults and they grow via a combination of reactant (monomer) consumption and oriented attachment at specific crystallographic surfaces because of the strong dipolar character of the < 111 > surfaces of magnetite. At a later stage of the synthesis reaction, the magnetic attraction strives to align contacting particles with their < 111 > axis of easy magnetization in parallel and this may also be an active driving force for crystal growth. At latter stages, the crystal growth is dominated by Ostwald ripening leading to smoother crystalline particles with a mean diameter of 16.7 +/- 3.5 nm and a narrow size distribution. The magnetic properties of the particles measured using static and dynamic magnetic fields are consistent with the evolution of particle size and structure and show the transition from superparamagnetic to thermally blocked behavior needed for magnetic relaxation-based immunoassay applications.

  • 61. Günay, M.
    et al.
    Erdemi, H.
    Baykal, A.
    Sözeri, H.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Triethylene glycol stabilized MnFe2O4 nanoparticle: Synthesis, magnetic and electrical characterization2013Ingår i: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 48, nr 3, s. 1057-1064Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, triethylene glycol (TEG) stabilized superparamagnetic MnFe2O4 nanoparticle (TEG@Mn-Fe2O4) was synthesized via a simple polyol route. Composition of nanoparticle was confirmed as MnFe2O4 and surface conjugation of TEG was confirmed by Fourier transform infrared spectroscopy to be via oxygens on TEG covalently attached to metal centers on the NPs: Vibrating sample magnetometer measurements confirmed the superparamagnetic character of these nanoparticles without reaching to a saturation, and has no coercivity. The TEG@MnFe2O4 nanocomposite showed thermally activated conductivity, significant interfacial polarization effect also in the dielectric permittivity evaluations. Temperature dependency of conductivity is a strong evidence for thermally activated polarization mechanism. dc conductivity is classified into two regions over a limited temperature range and shows maximum conductivity of about 4 x 10(-7) S cm(-1) at 120 degrees C. Temperature and frequency dependence of dielectric permittivity indicated interfacial polarization and temperature-assisted-reorganization effects.

  • 62. He, Zeming
    et al.
    Stiewe, Christian
    Platzek, Dieter
    Karpinski, Gabriele
    Mueller, Eckhard
    Li, Shanghua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Effect of ceramic dispersion on thermoelectric properties of nano ZrO2/CoSb3 composites2007Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, nr 4, s. 043707-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present work, nano- ZrO2 CoSb3 composites were fabricated by milling ZrO2 and CoSb3 powders and hot pressing at different sintering temperatures. For the prepared compacts, the phase purity, microstructure, and temperature-dependent thermoelectric properties were characterized. The effect of nano- ZrO2 dispersion on composite electrical conductivity and thermal conductivity is strictly clarified by comparing the transport properties of the nondispersed and dispersed CoSb3 at identical porosity, so that the effect of porosity on thermoelectric parameters could be eliminated. The effect of the insulating inclusion itself on transport properties is also considered and eliminated using effective media theories. It is clearly verified that charge carrier scattering and phonon scattering occur simultaneously to lower the electrical conductivity and the thermal conductivity of CoSb3 due to the introduction of nano- ZrO2 inclusions. The investigated composites show higher electrical conductivity due to existence of metallic Sb and lower thermal conductivity because of nanodispersion. At the ranges of high measuring temperature (673-723 K) and low porosity (6%-9%), the ratio of electrical conductivity to thermal conductivity of the dispersed CoSb3 is higher than that of nondispersed CoSb3, and the dimensionless figure of merit (ZT) of the composite could probably be improved at these ranges with the enhanced ratio of electrical conductivity to thermal conductivity and Seebeck coefficient, which is assumed to be increased by a potential barrier scattering.

  • 63.
    Hedberg, Yolanda
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Norell, Mats
    Materials and Manufacturing Technology, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Linhardt, Paul
    Institute for Chemical Technologies and Analytics (CTA), Vienna University of Technology, Getreidemarkt 9/164, A-1060 Vienna, Austria.
    Bergqvist, Hans
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Funktionella material, FNM (Stängd 20120101).
    Odnevall Wallinder, Inger
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Influence of Surface Oxide Characteristics and Speciation on Corrosion, Electrochemical Properties and Metal Release of Atomized 316L Stainless Steel Powders2012Ingår i: International Journal of Electrochemical Science, ISSN 1452-3981, E-ISSN 1452-3981, Vol. 7, nr 12, s. 11655-11677Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface oxide characteristics of powder particles are important to consider for any toxicological risk assessment based on in-vitro or in-vivo tests. This study focuses on a multi-analytical approach (X-ray photoelectron spectroscopy, Auger electron spectroscopy, scanning- and transmission electron microscopy, and different electrochemical techniques) for in-depth characterization of surface oxides of inert-gas-atomized (GA) AISI 316L stainless steel powder, compared with massive sheet and a water-atomized (WA) 316L powder. Implications of differences in surface oxide phases and their surface distribution on corrosion, electrochemical properties and metal release are systematically discussed. Cr was enriched in an inner surface layer for both GA powders, with Mn and S enriched in the outermost surface oxide. The surface oxide was 2-5 nm thick for both GA powder size fractions, amorphous for the GA powder sized <4 μm and partially crystalline for the powder sized <45 μm. A strong ennoblement, i.e. positive shift in open circuit potential, of up to 800 mV, depending on solution, was observed for the GA powders. This ennoblement was induced by catalytic oxygen reduction properties of tri- or tetravalent Mn-oxides, not present on the massive sheet or WA powder. In contrast to the predominant presence of a trivalent Cr-oxide in the surface oxide of the GA powder particles, the WA<45μm powder revealed oxidized Cr, most probably present in its hexavalent state (not chromate), within a silicate-rich surface oxide. This study clearly shows that the surface oxide composition and speciation of differently sized GA and WA powders are unique (strongly connected to the atomization process) and of large importance for their pitting corrosion and metal release properties. For the GA<45μm powder, Mn-rich oxide nanoparticles were proposed to account for its higher pitting corrosion susceptibility, a more stable surface ennoblement, and a shift of the MnO2 oxidation/reduction peaks in the cyclic voltammogram, compared with the GA particles sized <4μm. The thermodynamically unstable ferritic structure of the small sized particle fraction (GA <4μm), despite an austenitic composition, revealed a higher pitting corrosion susceptibility and higher nickel release compared with the austenitic particle fraction of the GA <45 μm powder.

  • 64. Karaoglu, E.
    et al.
    Baykal, A.
    Deligoz, H.
    Senel, M.
    Sozeri, H.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Synthesis and characteristics of poly(3-pyrrol-1-ylpropanoic acid) (PPyAA)-Fe(3)O(4) nanocomposite2011Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 509, nr 33, s. 8460-8468Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly(3-pyrrol-1-ylpropanoic acid) (PPyAA)-Fe(3)O(4) nanocomposite was successfully synthesized by an in situ polymerization of 1-(2-carboxyethyl) pyrrole in the presence of synthesized Fe(3)O(4) nanoparticles. Evaluation of structural, morphological, electrical and magnetic properties of the nanocomposite was performed by XRD, FT-IR, TEM, TGA, magnetization and conductivity measurements, respectively. XRD analysis reveals the inorganic phase as Fe(3)O(4) and TGA shows about 90 wt% loading of Fe(3)O(4) in the nanocomposite. FT-IR analysis indicates a successful conjugation of Fe(3)O(4) particles with polypyrrole acetic acid. Magnetization measurements show that polypyrrole acetic acid coating decreases the saturation magnetization of Fe(3)O(4) significantly. This reduction has been explained by the pinning of the surface spins by the possible adsorption of non-magnetic ions during the polymerization process. The conductivity and dielectric permittivity measurements strongly depend on the thermally activated polarization mechanism and thermal transition of PPyAA in the nanocomposite structure. Large value of dielectric permittivity (epsilon') of the nanocomposite at lower frequency is attributed to the predominance of species like Fe(2+) ions and grain boundary defects (interfacial polarization).

  • 65. Karaoglu, E.
    et al.
    Baykal, A.
    Şenel, M.
    Sözeri, H.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Synthesis and characterization of Piperidine-4-carboxylic acid functionalized Fe 3O 4 nanoparticles as a magnetic catalyst for Knoevenagel reaction2012Ingår i: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 47, nr 9, s. 2480-2486Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Piperidine-4-carboxylic acid (PPCA) functionalized Fe 3O 4 nanoparticles as a novel organic-inorganic hybrid heterogeneous catalyst was fabricated and characterized by XRD, FT-IR, TGA, TEM and VSM techniques. Composition was determined as Fe 3O 4, while particles were observed to have spherical morphology. Size estimations using X-ray line profile fitting (10 nm), TEM (11 nm) and magnetization fitting (9 nm) agree well, revealing nearly single crystalline character of Fe 3O 4 nanoparticles. Magnetization measurements reveal that PPCA functionalized Fe 3O 4 NPs have superparamagnetic features, namely immeasurable coercivity and absence of saturation. Small coercivity is established at low temperatures. The catalytic activity of Fe 3O 4-PPCA was probed through one-pot synthesis of nitro alkenes through Knoevenagel reaction in CH 2Cl 2 at room temperature. The heterogeneous catalyst showed very high conversion rates (97%) and could be recovered easily and reused many times without significant loss of its catalytic activity.

  • 66. Karaoglu, E.
    et al.
    Deligoz, H.
    Sozeri, H.
    Baykal, A.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Hydrothermal Synthesis and Characterization of PEG-Mn3O4 Nanocomposite2011Ingår i: Nano-Micro Letters, ISSN 2150-5551, Vol. 3, nr 1, s. 25-33Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Here, we report on the synthesis of PEG-5/Mn3O4 nanocomposite (NP's) via a hydrothermal route by using Mn(acac)(2), ethanol, NH3 and PEG-400. The crystalline phase was identified as Mn3O4. The crystallite size of the PEG-Mn3O4 nanocomposite was calculated as 12 +/- 5 urn from X-ray line profile fitting and the average particle size from TEM was obtained as 200 nm. This reveals polycrystalline character of Mn3O4 NP's. The interaction between PEG-400 and the Mn3O4 NP's was investigated by FTIR. Temperature independent AC conductivity of PEG-Mn3O4 nanocomposite beyond 20 kHz provides a strong evidence of ionic conduction through the structure. The conductivity and permittivity measurements strongly depend on the secondary thermal transition of nanocomposite beyond 100 degrees C. Above that temperature, Mn3O4 particles may interact with each other yielding a percolated path that will facilitate the conduction. On the other hand, the relatively lower activation energy (E-a=0.172 eV) for relaxation process suggests that polymer segmental motions of PEG and electrons hopping between Mn2+ and Mn3+ may be coupled in the sample below 100 degrees C. Room temperature magnetization curve of the sample does not reach to a saturation, which indicates the superparamagnetic character of the particles. As the temperature increases, the frequency at which (epsilon '') reaches a maximum shifted towards higher frequencies. The maximum peak was observed at 1.4 kHz for 20 degrees C while the maximum was detected at 23.2 kHz for 90 degrees C.

  • 67. Karaoglu, E.
    et al.
    Kavas, H.
    Baykal, A.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Sozeri, H.
    Effect of Hydrolyzing Agents on the Properties of Poly (Ethylene Glycol)-Fe3O4 Nanocomposie2011Ingår i: Nano-Micro Letters, ISSN 2150-5551, Vol. 3, nr 2, s. 79-85Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly (ethylene glycol) (PEG) assisted hydrothermal route has been used to study the influence of the hydrolyzing agent on the properties of PEG-iron oxide (Fe3O4) nanocomposites. Iron oxide nanoparticles (NPs), as confirmed by X-ray diffraction analysis, have been synthesized by a hydrothermal method in which NaOH and NH3 were used as hydrolyzing agents. Formation of PEG-Fe3O4 nanocomposite was confirmed by Fourier transform infrared spectroscopy (FTIR). Samples exhibit different crystallite sizes, which estimated based on line profile fitting as 10 nm for NH3 and 8 nm for NaOH hydrolyzed samples. The average particle sizes obtained from transmission electron microscopy was respectively 174 +/- 3 nm for NaOH and 165 +/- 4 nm for NH3 gas hydrolyzed samples. Magnetic characterization results reveal superparamagnetic characteristics despite a large particle size, which indicate the absence of coupling between the nanocrystals due to the presence of polymer in the nanocomposites. The conductivity curve demonstrates that sigma(DC) is strongly temperature dependent.

  • 68. Karaoglu, E.
    et al.
    Summak, M. M.
    Baykal, A.
    Sozeri, H.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Synthesis and Characterization of Catalytically Activity Fe(3)o(4)-3-Aminopropyl-triethoxysilane/Pd Nanocomposite2013Ingår i: Journal of Inorganic and Organometallic Polymers and Materials, ISSN 1574-1443, Vol. 23, nr 2, s. 409-417Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Herein we report the fabrication and characterization of Pd decorated Fe3O4 nanoparticles as highly effective catalysts for hydrogenation of 4-nitroaniline and 1,3-dinitrobenzene in liquid phase. The fabricated Fe3O4 nanoparticles exhibit an average size of 12 nm and super paramagnetic character with a high saturation magnetization (80 emu/g). The surface -NH2 groups effectively binds the in situ formed Pd nanoparticles. Thus formed Fe3O4-APTES-Pd(0) catalyst showed a very high catalytic activity in reduction reactions of 4-nitroaniline and 1,3-dinitrobenzene in liquid phase. Electron donor -NH2 groups supported Pd may be responsible for the increased catalytic activity. The superparamagnetic character of this system allows easy recovery and multiple uses without significant loss of its catalytic activity.

  • 69. Kavas, H.
    et al.
    Durmus, Z.
    Baykal, A.
    Aslan, A.
    Bozkurt, A.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Synthesis and conductivity evaluation of PVTri-Fe3O4 nanocomposite2010Ingår i: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 356, nr 9-10, s. 484-489Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly(1-vinyl-1,2,4-triazole) (PVTri)-Fe3O4 nanocomposite with conducting character was synthesized by a wet chemical process. PVTri has been freshly synthesized and coated/adsorbed on magnetite nanoparticles that are synthesized via a sonochemical route. The structure, morphology and electrical properties of the products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and Dielectric impedance spectroscopy, respectively. Crystallite size of magnetite was calculated by X-ray line profile fitting as 12 +/- 6 nm. FT-IR and TGA analysis confirm the adsorption of PVTri on magnetite nanoparticles. SEM micrographs revealed that Fe3O4 nanoparticles are slightly aggregated upon PVTri coating. Conductivity and permittivity measurements show the effect of glass transition temperature of polymer par in PVTri-Fe3O4 nanocomposite.

  • 70. Kavas, H.
    et al.
    Durmus, Z.
    Senel, M.
    Kazan, S.
    Baykal, A.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    CTAB-Mn3O4 nanocomposites: Synthesis, NMR and low temperature EPR studies2010Ingår i: Polyhedron, ISSN 0277-5387, E-ISSN 1873-3719, Vol. 29, nr 5, s. 1375-1380Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We are reporting on the synthesis of Mn3O4 nanoparticles and CTAB-Mn3O4 nanocomposites via a sonochemical route using MnCl2, ethanol, NaOH and CTAB. The crystalline phase was identified as Mn3O4. The crystallite size of the CTAB-Mn3O4 nanocomposite was identified as 13 +/- 5 nm from X-ray line profile fitting and the particle size from TEM was 107.5 +/- 1.4 nm. The interaction between CEAB and the Mn3O4 nanoparticles was investigated by FTIR and H-1 NMR spectroscopies. Two different magnetic phase transitions were observed for both samples below the Curie temperature (43 degrees C) by using a low temperature Electron Paramagnetic Resonance (EPR) technique. Also we determined the effect of the capping with CTAB on the reduction in absorbed power.

  • 71. Kavas, H.
    et al.
    Günay, M.
    Baykal, A.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Sozeri, H.
    Aktas, B.
    Negative Permittivity of Polyaniline-Fe3O4 Nanocomposite2013Ingår i: Journal of Inorganic and Organometallic Polymers and Materials, ISSN 1574-1443, Vol. 23, nr 2, s. 306-314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polyaniline-Fe3O4 nanocomposite with and without ionic liquid were successfully synthesized via in situ polymerization using cetyl trimethylammonium bromide (CTAB) as surfactant. Both TG analysis and FT-IR measurements proved the presence of organic layer on the surface of Fe3O4 nanoparticles. The influence of 1-butyl-3-methyl-imidazolium bromide (BMIMBr) as ionic liquid on the structure, conductivity, and magnetic property of PANI-Fe3O4-CTAB nanocomposite were studied in detail. The results show that imidazolium-based ionic liquids BMIMBr acts as an anchor agent during the formation of PANI-Fe3O4-CTAB nanocomposite. Ionic liquid significantly deteriorated nanocomposite's magnetic properties, and contributed to non-saturated M-H curve due to the disappearance of antiferromagnetic interactions. It has also an improving effect on AC and DC conductivities. The most important effect of IL is observed in real part of permittivity of PANI-Fe3O4-CTAB that it has negative high values at low frequency low temperature region. Due to the negative dielectric constant, material exhibits uncommon properties in electromagnetic waves scattering and attraction between similar charges. This possibility provokes research on these composites as high T superconductors, negative index materials and microwave absorbers.

  • 72. Kavas, Hueseyin
    et al.
    Baykal, Abduelhadi
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Koeseoglu, Yueksel
    Sertkol, Murat
    Aktas, Bekir
    Cation distribution and magnetic properties of Zn doped NiFe2O4 nanoparticles synthesized by PEG-assisted hydrothermal route2009Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 479, nr 1-2, s. 49-55Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanosize ZnxNi1-xFe2O4 spinel composites with x = 0, 0.2, 0.4, 0.6, 0.8 and I were synthesized by using surfactant (polyethylene glycol (PEG)) assisted hydrothermal route and characterized by TEM, XRD and VSM techniques. The crystallite size was calculated from different characterization methods, and magnetic core size was found to be in the range of 9-20 nm from VSM. All particles showed superparamagnetic character at room temperature and M, decreased with increasing concentration of Zn2+. Due to the bigger ionic radius of Zn2+ with respect to Ni2+, the unit cell parameter 'a' increased linearly with increasing x, likewise, the oxygen positional parameter 'u' increased theoretically and experimentally as observed in the literature. Particle size was observed to decrease by substitution of Zn. The cation distribution has been calculated analytically by using X-ray diffraction data and Fe3+ cations were found to occupy mostly tetrahedral sites revealing almost an inverse-spinel structure. These results are proved to be consistent with the results of magnetic measurements. The site preference of Fe3+ cations on tetra sublattice is attributed to the synthesis conditions utilizing surfactant and low temperature.

  • 73.
    Kunzmann, Andrea
    et al.
    Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
    Andersson, Britta
    Clinical Allergy Research Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
    Vogt, Carmen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Feliu, Neus
    Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
    Ye, Fei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Gabrielsson, Susanne
    Clinical Allergy Research Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Buerki-Thurnherr, Tina
    Labortory for Materials, Biology Interactions, Swiss Federal Laboratories of Materials Testing and Research, St. Gallen, Switzerland.
    Laurent, Sophie
    NMR and Molecular Imaging Laboratory, Department of General, Organic and Biomedical Chemistry, University of Mons, Belgium.
    Vahter, Marie
    Krug, Harald
    Division of Metals and Health, Institute of Environmental Medicine, Karolinska Insitutetet, Stockholm, Sweden.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Scheynius, Annika
    Clinical Allergy Research Unit, Department of Medicine, Karolinska Institutet and Universty Hospital Solan, Sweden.
    Fadeel, Bengt
    Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
    Efficient internalization of silica-coated iron oxide nanoparticles of different sizes by primary human macrophages and dendritic cells2011Ingår i: Toxicology and Applied Pharmacology, ISSN 0041-008X, E-ISSN 1096-0333, Vol. 253, nr 2, s. 81-93Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Engineered nanoparticles are being considered for a wide range of biomedical applications, from magnetic resonance imaging to "smart" drug delivery systems. The development of novel nanomaterials for biomedical applications must be accompanied by careful scrutiny of their biocompatibility. In this regard, particular attention should be paid to the possible interactions between nanoparticles and cells of the immune system, our primary defense system against foreign invasion. On the other hand, labeling of immune cells serves as an ideal tool for visualization, diagnosis or treatment of inflammatory processes, which requires the efficient internalization of the nanoparticles into the cells of interest. Here, we compare novel monodispersed silica-coated iron oxide nanoparticles with commercially available dextran-coated iron oxide nanoparticles. The silica-coated iron oxide nanoparticles displayed excellent magnetic properties. Furthermore, they were nontoxic to primary human monocyte-derived macrophages at all doses tested whereas dose-dependent toxicity of the smaller silica-coated nanoparticles (30 nm and 50 nm) was observed for primary monocyte-derived dendritic cells, but not for the similarly small dextran-coated iron oxide nanoparticles. No macrophage or dendritic cell secretion of pro-inflammatory cytokines was observed upon administration of nanoparticles. The silica-coated iron oxide nanoparticles were taken up to a significantly higher degree when compared to the dextran-coated nanoparticles, irrespective of size. Cellular internalization of the silica-coated nanoparticles was through an active, actin cytoskeleton-dependent process. We conclude that these novel silica-coated iron oxide nanoparticles are promising materials for medical imaging, cell tracking and other biomedical applications. (C) 2011 Elsevier Inc. All rights reserved.

  • 74.
    Li, Jiantong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ye, Fei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    A simple route towards high-concentration surfactant-free graphene dispersions2012Ingår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 50, nr 8, s. 3113-3116Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A simple solvent exchange method is introduced to prepare high-concentration and surfactant-free graphene liquid dispersion. Natural graphite flakes are first exfoliated into graphene in dimethylformamide (DMF). DMF is then exchanged by terpineol through distillation, relying on their large difference in boiling points. Graphene can then be concentrated thanks to the volume difference between DMF and terpineol. The concentrated graphene dispersions are used to fabricate transparent conductive thin films, which possess comparable properties to those prepared by more complex methods.

  • 75.
    Li, Shanghua
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Furberg, Richard
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Palm, Björn E.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Nature-inspired boiling enhancement by novel nanostructured macroporous surfaces2008Ingår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 18, nr 15, s. 2215-2220Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    World energy crisis has triggered more attention to energy saving and energy conversion systems. Enhanced surfaces for boiling are among the applications of great interest since they can improve the energy efficiency of heat pumping equipment (i.e., air conditioners, heat pumps, refrigeration machines). Methods that are used to make the state-of-the-art enhanced Surfaces are often based on complicated mechanical machine tools, are quite material-consuming and give limited enhancement of the boiling heat transfer. Here, we present a new approach to fabricate enhanced surfaces by using a simple electrodeposition method with in-situ grown dynamic gas bubble templates. As a result, a well-ordered 3D macro-porous metallic surface layer with nanostructured porosity is obtained. Since the structure is built based on the dynamic bubbles, it is perfect for the bubble generation applications Such as nucleate boiling. At heat flux of 1W cm(-2), the heat transfer coefficient is enhanced over 17 times compared to a plain reference Surface. It's estimated that such ail effective boiling surface Would improve the energy efficiency of many heat Pumping machines with 10-30%. The extraordinary boiling performance is explained based on the structure characteristics.

  • 76.
    Li, Shanghua
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Furberg, Richard
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Toprak, Muhammet
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Zhang, Yu
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Fabrication of nanostructured micro-porous surfaces for enhanced boilingManuskript (Övrigt vetenskapligt)
  • 77.
    Li, Shanghua
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Meng Lin, Meng
    Toprak, Muhammet S
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Kim, Do Kyung
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Nanocomposites of polymer and inorganic nanoparticles for optical and magnetic applications2010Ingår i: Nano reviews, ISSN 2000-5121, Vol. 1, s. 5214-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article provides an up-to-date review on nanocomposites composed of inorganic nanoparticles and the polymer matrix for optical and magnetic applications. Optical or magnetic characteristics can change upon the decrease of particle sizes to very small dimensions, which are, in general, of major interest in the area of nanocomposite materials. The use of inorganic nanoparticles into the polymer matrix can provide high-performance novel materials that find applications in many industrial fields. With this respect, frequently considered features are optical properties such as light absorption (UV and color), and the extent of light scattering or, in the case of metal particles, photoluminescence, dichroism, and so on, and magnetic properties such as superparamagnetism, electromagnetic wave absorption, and electromagnetic interference shielding. A general introduction, definition, and historical development of polymer-inorganic nanocomposites as well as a comprehensive review of synthetic techniques for polymer-inorganic nanocomposites will be given. Future possibilities for the development of nanocomposites for optical and magnetic applications are also introduced. It is expected that the use of new functional inorganic nano-fillers will lead to new polymer-inorganic nanocomposites with unique combinations of material properties. By careful selection of synthetic techniques and understanding/exploiting the unique physics of the polymeric nanocomposites in such materials, novel functional polymer-inorganic nanocomposites can be designed and fabricated for new interesting applications such as optoelectronic and magneto-optic applications.

  • 78.
    Li, Shanghua
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Fornara, Andrea
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Kim, Do Kyung
    Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites2009Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 20, nr 18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

  • 79.
    Li, Shanghua
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Zhang, Shuo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    He, Zeming
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Stiewe, Christian
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Mueller, Eckhard
    Novel Solution Route Synthesis of Low Thermal Conductivity Nanocrystalline Bismuth Telluride2010Ingår i: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 10, nr 11, s. 7658-7662Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel synthesis approach based on a solution route has been developed for the fabrication of nanocrystalline bismuth telluride. The method consists of dissolving both bismuth and tellurium into the same organic solvent with the assistance of complexing agents and one-step coprecipitation of bismuth telluride. The synthesized nanocrystalline bismuth telluride powders possess rhombohedral crystal structure and are nanosheet/nanorod-like with an average size of between 30 and 40 nm. The thermal conductivity of the hot-pressed compact consolidated from the as-synthesized nanopowders is 0.39-0.45 Wm(-1)K(-1) in the temperature range of 323 to 523 K, which is at most one third of that of bulk bismuth telluride-based materials reported in the literature. Such low thermal conductivity of the investigated bismuth telluride is mainly attributed to substantially high concentration of grain boundaries provided by nanostructuring to scatter phonons intensively.

  • 80. Li, Song
    et al.
    Wang, Xiaodi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Novel ceramic fuel cell using non-ceria-based composites as electrolyte2007Ingår i: Electrochemistry communications, ISSN 1388-2481, E-ISSN 1873-1902, Vol. 9, nr 12, s. 2863-2866Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel concept of ceramic or solid oxide fuel cell (SOFC) based on non-ceria-salt-composites electrolyte has been investigated. The fuel cell using LiAlO2-carbonate (LiNaCO3) as electrolyte exhibits excellent performances, when we used hydrogen and air as fuel and oxidant respectively, instead of molten carbonate fuel cells (MCFCs) environment. The maximum output power density can reach 466 mW/cm(2) at 650 degrees C and the discharging current keeps constant. The ion transport mechanics of the ceramic fuel cell were discussed. In the H-2/air atmosphere, the new fuel cell function should be performed only by proton or oxygen ion conduction, which differs essentially from the MCFC function, in which the CO32- conduction dominates process.

  • 81. Lin, Meng Meng
    et al.
    Kim, Hyung-Hwan
    Kim, Hyuck
    Dobson, Jon
    Kim, Do Kyung
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Surface activation and targeting strategies of superparamagnetic iron oxide nanoparticles in cancer-oriented diagnosis and therapy2010Ingår i: NANOMEDICINE, ISSN 1743-5889, Vol. 5, nr 1, s. 109-133Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The advanced fabrication and surface engineering of superparamagnetic iron oxide nanoparticles (SPIONs) could offer excellent physiochemical features for noninvasive tumor imaging and drug delivery. The key issues of realization of maximized selective cancer targeting of SPIONs are minimization of uptake by macrophages, preferential binding to cancerous cells over neighboring normal cells, visualization of tumor cells prior to and after treatment and triggered drug release into target cells in a controlled fashion. In this article, we summarize the current status of fabrication of multifunctional SPION-based nanodevices specially designed for cancer-oriented diagnosis and therapy, with a focus on potential malignancy-targeting ligands' identification and development as nanocarriers. A number of examples of passive and active targeting strategies - lymphoangiogenesis markers, cellular metabolite receptors, extracellular matrix component receptors, neuropeptide receptors and receptor-mediated bypass of the blood-brain barrier - are described in detail.

  • 82. Lin, Meng Meng
    et al.
    Li, Shanghua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Kim, Hyung-Hwan
    Kim, Hyuck
    Lee, Hyung Bock
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Kim, Do-Kyung
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Complete separation of magnetic nanoparticles via chemical cleavage of dextran by ethylenediamine for intracellular uptake2010Ingår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 20, nr 3, s. 444-447Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Completely water dispersible and highly monodispersed superparamagnetic iron oxide nanoparticles (SPIONs) were prepared. The surface of SPIONs was modified with dual-crosslinked amine activated dextran (AMD) and chemical cleavage of AMD on SPIONs was carried out by ethylenediamine hydrochloride (EDA). Transmission electron microscopy (TEM) revealed that individual SPIONs were completely separated in water and the average diameter of resulting nanoparticles was 4.4 nm.

  • 83.
    Ma, Ying
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Ceria-based Nanostructured Materials for Low-Temperature Solid Oxide Fuel Cells2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    As one of the most efficient and environmentally benign energy conversion devices, solid oxide fuel cells (SOFC) have attracted much attention in recent years. Conventional SOFC with yttria-stabilized zirconia as electrolyte require high operation temperature (800-1000 °C), which causes significant problems like material degradation, as well as other technological complications and economic barrier for wider applications. Therefore, there is a broad interest in reducing the operation temperature of SOFCs. One of the most promising ways to develop low-temperature SOFCs (LTSOFC) is to explore effective materials for each component with improved properties. So in this thesis, we are aiming to design and fabricate ceria-based nanocomposite materials for electrolyte and electrodes of LTSOFC by a novel nanocomposite approach.

    In the first part of the thesis, novel core-shell doped ceria/Na2CO3 nanocomposite was fabricated and investigated as electrolytes materials of LTSOFC. Two types of doped ceria were selected as the main phase for nanocomposite: samarium doped ceria (SDC) and calcium doped ceria (CDC). The core-shell SDC/Na2CO3 nanocomposite particles are smaller than 100 nm with amorphous Na2CO3 shell of 4~6 nm in thickness. The ionic conductivity of nanocomposite electrolytes were investigated by EIS and four-probe d.c. method, which demonstrated much enhanced ionic conductivities compared to the single phase oxides. The thermal stability of such nanocomposite has also been investigated based on XRD, BET, SEM and TGA characterization after annealing samples at various temperatures. Such nanocomposite was applied in LTSOFCs with an excellent power density of 0.8 Wcm-2 at 550 °C. The high performances together with notable thermal stability prove the doped ceria/Na2CO3 nanocomposite as a potential electrolyte material for long-term LTSOFCs.

    In the second part of the thesis, a novel template-, surfactant-free chemical synthetic route has been successfully developed for the controlled synthesis of hierarchically structured CeO2 with nanowires and mesoporous microspheres morphologies. The new synthetic route was designed by utilizing the chelate formation between cerium ion and various carboxylates forms of citric acid. Then, hierarchically structured cerium oxide with morphologies of nanowires and mesoporous microspheres can be obtained by thermal decomposition of the two kinds of precursors. Moreover, by doping with desired elements, SDC nanowires and SDC-CuO mesoporous microspheres were prepared and used for electrolyte and anode materials, respectively, based on their unique properties depending on their morphologies. When SDC nanowires/Na2CO3 composite were applied as electrolyte for single SOFC, and it exhibited maximum power density of 522 mWcm-2 at 600 °C, which is much better than the state-of-the-art SOFCs using doped ceria as electrolytes. Besides, the mesoporous CuO-SDC composite anode was synthesized by our microwave-assisted method, which shows good phase homogeneity of both SDC and CuO. When it was applied for fuel cells, the cell had better performance than conventional CuO-SDC anode prepared by solid state method.

    The whole work of this thesis aims to provide a new methodology for the entire SOFC community. It is notable that our work has attracted considerable attention after publication of several attached papers. The results in this thesis may benefit the development of LTSOFC and expand the related research to a new horizon.

  • 84.
    Ma, Ying
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Wang, Xiaodi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Khalifa, Hassan Ahmed
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Enhanced ionic conductivity in calcium doped ceria - Carbonate electrolyte: A composite2012Ingår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, nr 24, s. 19401-19406Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, ceria-based nanocomposites, as a proton and oxygen ion conductor, has been developed as promising electrolyte candidates for low-temperature solid oxide fuel cells (LTSOFCs). Up to now, samarium doped ceria (SDC) was studied as a main oxide for nanocomposite electrolyte; while calcium doped ceria (CDC) is considered as a good alternative from both material performance and economical aspects. Yet the conduction behavior of CDC-based composite has not been reported. In the present study, calcium doped ceria was prepared by oxalate co-precipitation method, and used for the fabrication of CDC/Na2CO3 composite. The thermal decomposition process, structure and morphology of the samples were characterized by TGA, XRD, SEM, etc. The oxygen ion conductivity of single phase CDC sample was measured by electrochemical impedance spectroscopy (EIS), while the proton and oxygen ion conductivity of CDC/Na2CO3 nanocomposite sample were determined by four-probe d.c. measurements. The CDC/Na2CO3 samples show significantly enhanced overall ionic conductivity compared to that of single phase CDC samples, demonstrating pronounced composite effect. This confirms that the use of nanocomposite as electrolyte can effectively lower the operation temperature of SOFC due to improved ionic conductivity.

  • 85.
    Ma, Ying
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Wang, Xiaodi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Li, Shanghua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Samarium-doped ceria nanowires: Novel synthesis and application in low-temperature solid oxide fuel cells2010Ingår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 22, nr 14, s. 1640-1644Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Samarium-doped ceria (SDC) nanowires are synthesized by a novel, template-, surfactant-free and cost-effective method, using citric acid as precipitating/complexing agent for formation of citrate precursor nanowires. The single SOFC based on SDC nanowires/Na2CO3 nanocomposites as electrolyte is fabricated and the maximum power densities of 417 and 522 mW cm-2 at 550 and 600°C are achieved, showing great potential for low-temperature SOFCs.

  • 86.
    Ma, Ying
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Wang, Xiaodi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Raza, Rizwan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Thermal stability study of SDC/Na2CO3 nanocomposite electrolyte for low temperatur SOFCs2010Ingår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 35, nr 7, s. 2580-2585Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The novel core-shell nanostructured SDC/Na2CO3 composite has been demonstrated as a promising electrolyte material for low-temperature SOFCs. However, as a nanostructured material, stability might be doubted under elevated temperature due to their high surface energy. So in order to study the thermal stability of SDC/Na2CO3 nanocomposite, XRD, BET, SEM and TGA characterizations were carried on after annealing samples at various temperatures. Crystallite sizes, BET surface areas, and SEM results indicated that the SDC/Na2CO3 nanocomposite possesses better thermal stability on nanostructure than pure SDC till 700 °C. TGA analysis verified that Na2CO3 phase exists steadily in the SDC/Na2CO3 composite. The performance and durability of SOFCs based on SDC/Na2CO3 electrolyte were also investigated. The cell delivered a maximum power density of 0.78 W cm-2 at 550 °C and a steady output of about 0.62 W cm-2 over 12 h operation. The high performances together with notable thermal stability make the SDC/Na2CO3 nanocomposite as a potential electrolyte material for long-term SOFCs that operate at 500-600 °C.

  • 87.
    Ma, Ying
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Wang, Xiaodi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    A surfactant and template-free route for controlled synthesis of hierarchically structured cerium oxides with tunable morphologies and their application for water treatmentArtikel i tidskrift (Övrigt vetenskapligt)
  • 88.
    Ma, Ying
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Wang, Xiaodi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Microwave synthesis of mesoporous Cu-Ce0.8Sm0.2O 2-δ composite anode for low-temperature ceramic fuel cells2013Ingår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, nr 1, s. 597-602Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In recent year, new nanocomposite electrolytes materials have been developed for low-temperature ceramic fuel cells (CFCs). To further improve the performance of CFCs based on the nanocomposite electrolyte, compatible active anode with sufficient low polarizations is needed. To improve the performance of anode, i.e. to enlarge tripe phase boundaries (TPB), anode materials with both porous structure and phase homogeneity of metal and ceramic are preferred. In the present study, we developed a novel microwave-assisted template-, surfactant-free synthesis route for mesoporous CuO-Ce0.8Sm 0.2O2-δ composite anode by homogeneous precipitation of microspherical precursor in aqueous solutions followed by calcination. The composite anode sample was characterized by thermogravimetry analysis, X-ray diffraction, SEM, EDX, etc. The characterization results indicated that CuO-SDC composite anode with mesoporous structure was prepared and both SDC and CuO phases were homogenously distributed. Fuel cells have been constructed using as-prepared composite as anodes and lithiated NiO as cathode based on the SDC-carbonate nanocomposite electrolyte. Fuel cell performance tests indicated that the cell with mesoporous Cu-SDC anode had better performance than conventional Cu-SDC anode prepared by solid-state method.

  • 89.
    Ma, Ying
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Wang, Xiaodi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Microwave synthesis of mesoporous CuO-Ce0.8Sm0.2O2-δ composite anode for low-temperature SOFCsArtikel i tidskrift (Övrigt vetenskapligt)
  • 90.
    Ma, Ying
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Funktionella material, FNM (Stängd 20120101).
    Wang, Xiaodi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Funktionella material, FNM (Stängd 20120101).
    Zhu, Bin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Funktionella material, FNM (Stängd 20120101).
    Muhammed, Mamoun Ali
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Funktionella material, FNM (Stängd 20120101).
    Single step synthesis of mesoporous nio-CE0.8SM0.2O2-δ composite anode for low-temperature SOFC2011Ingår i: EFC 2011 - Proceedings of the 4th European Fuel Cell Piero Lunghi Conference and Exhibition, 2011, s. 293-294Konferensbidrag (Refereegranskat)
    Abstract [en]

    The performance of the CeO2-based composite anodes depends on microstructural features such as particle size, tripe phase boundaries (TPB), surface area, and percolation. To improve the performance of anode, i.e. to enlarge TPB, anode materials with both porous structure and phase homogeneity of metal and ceramic are preferred. In the present study, we developed a novel onestep template-, surfactant-free synthesis route for mesoporous CE0.8SM0.2O2-δ composite anode by homogeneous precipitation of precursor in aqueous solutions followed by calcination. The composite anode sample was characterized by thermogravimetry analysis, X-ray diffraction, SEM, BET, etc. The refinement of the XRD data indicated that the composite sample synthesized by the process called "one step synthesis" produced smaller crystallite size in comparison to the sample attained by the two steps process. Fuel cells have been constructed using as-prepared composite as anodes and lithiated NiO as cathode based on the SDCcarbonate composite electrolyte. Simple preliminary performance tests were done with single cells in which such I-V curves indicated that the cell with one step anode had better performance.

  • 91. Madami, M.
    et al.
    Bonetti, S.
    Consolo, G.
    Tacchi, S.
    Carlotti, G.
    Gubbiotti, G.
    Mancoff, F. B.
    Yar, Mazher Ahmed
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Akerman, J.
    Direct observation of a propagating spin wave induced by spin-transfer torque2011Ingår i: Nature Nanotechnology, ISSN 1748-3387, E-ISSN 1748-3395, Vol. 6, nr 10, s. 635-638Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spin torque oscillators with nanoscale electrical contacts(1-4) are able to produce coherent spin waves in extended magnetic films, and offer an attractive combination of electrical and magnetic field control, broadband operation(5,6), fast spin-wave frequency modulation(7-9), and the possibility of synchronizing multiple spin-wave injection sites(10,11). However, many potential applications rely on propagating (as opposed to localized) spin waves, and direct evidence for propagation has been lacking. Here, we directly observe a propagating spin wave launched from a spin torque oscillator with a nanoscale electrical contact into an extended Permalloy (nickel iron) film through the spin transfer torque effect. The data, obtained by wave-vector-resolved micro-focused Brillouin light scattering, show that spin waves with tunable frequencies can propagate for several micrometres. Micromagnetic simulations provide the theoretical support to quantitatively reproduce the results.

  • 92. Monteiro-Riviere, N. A.
    et al.
    Inman, A. O.
    Mathur, S.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Fadeel, B.
    Riviere, J. E.
    Effects of eight nanoparticles of different sizes and shapes on human epidermal keratinocytes2012Ingår i: Journal of Investigative Dermatology, ISSN 0022-202X, E-ISSN 1523-1747, Vol. 132, s. S52-S52Artikel i tidskrift (Övrigt vetenskapligt)
  • 93. Muhammed, Mamoun
    et al.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Nanostructured Skutterudites2006Ingår i: Thermoelectrics Handbook: Macro to Nano-Structured Materials / [ed] D.M. Rowe, Taylor & Francis Group, 2006, s. 41-1-41-10Kapitel i bok, del av antologi (Refereegranskat)
  • 94.
    Noroozi, Mohammad
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Ergül, Adem
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Abedin, Ahmed
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Toprak, Muhammet S
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Funktionella material, FNM (Stängd 20120101).
    Radamson, Henry
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Fabrications of size-controlled SiGe nanowires using I-line lithography and focused ion beam technique2014Ingår i: ECS Transactions, 2014, nr 6, s. 167-174Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this study, a novel method using Focus Ion Beam (FIB) technique was applied to scale down Si1-xGex wires (x=0.27-0.57) to 20 nm width. Originally, the wires were processed by using Iline lithography and dry etching of SiGe on oxide (SGOI) substrates. The SGOI wafers were processed through condensation method where a SiGe/Si layer was grown in the beginning on SOI wafers and oxidized at 850-1050 °C. The shape of the nanowires (NWs) during the successive FIB cutting was examined by scanning electron microscopy (SEM) and the carrier transport through the NWs was checked by resistivity measurements. The contact resistance was reduced by Ni-silicide prior to metallization. The fabricated NWs were also suspended by tilting FIB. The results present the limitations and challenges of FIB technique to create NWs for advanced sensors and transistors.

  • 95.
    Okoli, Chuka
    et al.
    KTH, Skolan för bioteknologi (BIO), Miljömikrobiologi. KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Fornara, Andrea
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Dalhammar, Gunnel
    KTH, Skolan för bioteknologi (BIO), Miljömikrobiologi.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Rajarao, Gunaratna
    KTH, Skolan för bioteknologi (BIO), Miljömikrobiologi.
    Characterization of Superparamagnetic Iron Oxide Nanoparticles and Its Application in Protein Purification2011Ingår i: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 11, nr 11, s. 10201-10206Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The application of surface modified magnetic adsorbent particles in combination with magnetic separation techniques has received considerable awareness in recent years. There is a particular need in protein purification and analysis for specific, functional and generic methods of protein binding on solid supports. Nanoscale superparamagnetic iron oxide particles have been used to purify a natural coagulant protein extracted from Moringa oleiferaseeds. Spectrophotometric analysis of the coagulant protein was performed using synthetic clay solution as substrate. Protein binding with carboxyl and silica surface modified superparamagnetic iron oxide nanoparticles (SPION) were compared with the known carboxyl methyl cellulose (CMC) beads of ∼1 m. SPION modified with carboxyl surface showed higher binding capacity towards the coagulant protein compared to the CMC beads. The high surface area to volume ratio of the carboxyl-coated SPION resulted in high binding capacity and rapid adsorption kinetics of the crude protein extract. The purification and molecular weight of coagulant protein is analyzed by SDS-PAGE. This approach utilizes the most efficient, feasible and economical method of coagulant protein purification and it can also be applicable to other proteins that possess similar properties.

  • 96. Ozkaya, T.
    et al.
    Baykal, A.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Koseoglu, Y.
    Durmus, Z.
    Reflux synthesis of Co3O4 nanoparticles and its magnetic characterization2009Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 321, nr 14, s. 2145-2149Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Co3O4 nanoparticles have been prepared for the first time via reflux method, as an alternative low-temperature high-yield process, starting from one single precursor. A plausible mechanism is suggested for the synthetic process. XRD, TEM, FTIR and VSM were used for the structural, morphological, spectroscopic, and magnetic characterization of the product respectively. X-ray diffraction line profile fitting showed that average particle size of the sample is 28 nm. Morphology of the synthesized powder was observed to be thin nanosheets with a thickness of 2-3 nm based on SEM and TEM analyses. Magnetic measurements showed a deviation of the Neel temperature from the bulk value which is attributed to the finite size effects. A loop shift with an enhanced coercivity is observed in the field-cooled hysteresis loops. The opening of the hysteresis loop reveals the existence of the spin-glass like surface spins of the Co3O4 nanoparticles.

  • 97.
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Environment-Sensitive Multifunctional Drug Delivery Systems2010Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Drug delivery systems (DDS) with multiple functionalities such as environment-sensitive drug release mechanisms and visualization agents have motivated the biomedical community as well as materials chemists for more than a decade. This dissertation is concerned with the development of nanoparticles for multifunctional DDS  to tackle several crucial challenges in these complex systems, including polymeric nanospheres which respond to temperature change, superparamagnetic iron oxide nanoparticles/polymeric composite for magnetic resonance imaging contrast agents and drug carriers, immunoresponse of nanomaterials and injectable magnetic field sensitive ferrogels.

    The biocompatible and biodegradable polylactide (PLA) was employed as matrix materials for polymeric nanosphere-based DDS. The thermosensitive polymeric nanospheres have been constructed through a “modified double-emulsion method”. The inner shell containing the thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) undergoes a “hydrophilic-to-hydrophobic” phase transition around the human body temperature. The sensitivity of the polymer to the temperature can facilitate drug release at an elevated temperature upon administration. In addition, gold nanoparticles were assembled on the dual-shell structure to form a layer of gold shell. The cell viability was found to be enhanced due to the gold layer. The immunoresponse of the gold nanoparticles has been considered even if no acute cytotoxicity was observed.

    Imaging is another functionality of multifunctional DDS. This work focuses on magnetic resonance imaging (MRI) and involves synthesis and surface modification of superparamagnetic iron oxide nanoparticles (SPIONs) for contrast agents. The SPIONs have been prepared through a high temperature decomposition method. Surface modification was carried out in different ways. Poly(L,L-lactide) (PLLA) was grafted on SPIONs through surface-initiated ring-opening polymerization. The hydrophobic model drug indomethacin was loaded in the PLLA layer of the composite particles. For biomedical applications, it is essential to modify the hydrophobic particles so that they can be dispersed in physiological solutions. A series of protocols including using small charged molecules and amphiphilic polymers has been established. Pluronic F127 (PF127), a triblock copolymer was applied as a phase transfer reagent. Most interestingly, PF127@SPIONs show remarkable efficacy as T2 contrast agents. The PF127@SPIONs have been successfully applied to image the cochlea in a rat model. As another phase transfer reagent, poly(maleic anhydride-alt-octadecene)-graft-PNIPAAm (PMAO-graft-PNIPAAm) was created for surface modification of SPIONs. This new copolymer provides the modified SPIONs with thermosensitivity together with water-dispersibility.

    As another form of DDS, ferrogel made of PF127 copolymer and SPIONs was developed. Gelation process depends on the temperature of the SPIONs/PF127 mixture. This property makes it possible to use the ferrogel as an injectable drug carrier. Unlike other ferrogels based on crosslinked polymeric network, the PF127 ferrogel can entrap and release hydrophobic drugs. Application of an external magnetic field is found to enhance the drug release rate. This property can find application in externally stimulated local drug release applications.

  • 98.
    Qin, Jian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Asempah, Isaac
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Laurent, Sophie
    Department of General Organic and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons-Hainaut.
    Fornara, Andrea
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muller, Robert N.
    Department of General Organic and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons-Hainaut.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Injectable Superparamagnetic Ferrogels for Controlled Release of Hydrophobic Drugs2009Ingår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 21, nr 13, s. 1354-1357Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A ferrogel for magnetically controlled release of drugs is prepared by integration of superparamagnetic iron oxide nanoparticles and Pluronic F127 gels. The hydrophobic drug indomethacin is loaded in the ferrogel owing to the oil-in-water micellar structure. The characteristic solgel transition property renders the ferrogel an injectable drug carrier that will be, in principle, free from surgical implant procedure.

  • 99.
    Qin, Jian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Jo, Suk
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Coating Nanocrystals with Amphiphilic Thermosensitive Copolymers2009Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 48, nr 42, s. 7845-7849Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Well-dressed: A new method was developed to produce thermosensitive nanocrystals (NCs) by coating the NCs with an amphiphilic copolymer consisting of poly(maleic anhydride-alt-1-octadecene) (PMAO) and poly(N-isopropylacrylamide) (PNIPAAm; see photograph of coated Fe3O4 NCs at 20 °C and 40 °C). The method is general for all hydrophobic NCs produced by thermolysis.

  • 100.
    Qin, Jian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Jo, Yun Suk
    Ihm, Jong Eun
    Kim, Do Kyung
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Thermosensitive nanospheres with a gold layer revealed as low-cytotoxic drug vehicles2005Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, nr 20, s. 9346-9351Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, the positive effect of a gold layer on cell viability is demonstrated by examining the results given by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfop henyl)-2H-tetrazolium (MTS) assay and two-color cell fluorescence viability (TCCV) assay. These cytotoxicity tests were performed with human cervical adenocarcinoma cells (HeLa cell line) and transformed African green monkey kidney fibroblast cells (Cos-7 cell line). To fabricate the nanostructures as drug vehicles, first, poly((L),(L)-lactidec-co-ethylene glycol) (PLLA-PEG) and poly(N-isopropylacrylamide-co-(D),(D)-lactide) (PNIPAAm-PDLA) were synthesized, and then two kinds of thermosensitive nanospheres comprising "shell-in-shell" structures without a gold layer (PLLA-PEG@PNIPAAm-PDLA) and with a gold layer (Au@PLLA-PEG@PNIPAAmPDLA) were constructed by a modified double-emulsion method (MDEM). Both of them displayed a unique thermosensitive character exhibiting the lower critical solubility temperature (LCST) at 36.7 degrees C which was confirmed by LTV-vis spectroscopy and differential scanning calorimetry (DSC). The release profiles of entrapped bovine serum albumin (BSA) were monitored at 22 and 37 degrees C, respectively, to reveal the thermal dependence on the release rate. In cell viability tests, both PLLA-PEG@PNIPAAm-PDLA and Au@PLLAPEGCd)PNIPAAm-PDLA showed excellent cell viability, and furthermore, Au@PLLA-PEG@PNIPAAmPDLA, particularly at high doses, exhibited more enhanced cell viability than PLLA-PEGCa)PNTPAAm-PDLA. This effect is mainly attributed to the gold layer which binds the protein molecules first and consequently facilitates transmembrane uptake of essential nutrients in the cell media, resulting in favorable cell proliferation.

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