Change search
Refine search result
123456 101 - 150 of 259
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 101. Kavas, Hueseyin
    et al.
    Baykal, Abduelhadi
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Koeseoglu, Yueksel
    Sertkol, Murat
    Aktas, Bekir
    Cation distribution and magnetic properties of Zn doped NiFe2O4 nanoparticles synthesized by PEG-assisted hydrothermal route2009In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 479, no 1-2, p. 49-55Article in journal (Refereed)
    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.

  • 102. Kertmen, Ahmet
    et al.
    Torruella, Pau
    Coy, Emerson
    Yate, Luis
    Nowaczyk, Grzegorz
    Gapinski, Jacek
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Toprak, Muhammet
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Estrade, Sonia
    Peiro, Francesca
    Milewski, Slawomir
    Jurga, Stefan
    Andruszkiewicz, Ryszard
    Acetate-Induced Disassembly of Spherical Iron Oxide Nanoparticle Clusters into Monodispersed Core-Shell Structures upon Nanoemulsion Fusion2017In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 33, no 39, p. 10351-10365Article in journal (Refereed)
    Abstract [en]

    It has been long known that the physical encapsulation of oleic acid-capped iron oxide nanoparticles (OA-IONPs) with the cetyltrimethylammonium (CTA(+)) surfactant induces the formation of spherical iron oxide nanoparticle clusters (IONPCs). However, the behavior and functional properties of IONPCs in chemical reactions have been largely neglected and are still not well-understood. Herein, we report an unconventional ligand-exchange function of IONPCs activated when dispersed in an ethyl acetate/acetate buffer system. The ligand exchange can successfully transform hydrophobic OA-IONP building blocks of IONPCs into highly hydrophilic, acetate-capped iron oxide nanoparticles (Ac-IONPs). More importantly, we demonstrate that the addition of silica precursors (tetraethyl orthosilicate and 3-aminopropyltriethoxysilane) to the acetate/oleate ligand-exchange reaction of the IONPs induces the disassembly of the IONPCs into monodispersed iron oxide-acetate-silica core-shell-shell (IONPs@acetate@SiO2) nanoparticles. Our observations evidence that the formation of IONPs@acetate@SiO2 nanoparticles is initiated by a unique micellar fusion mechanism between the Pickering-type emulsions of IONPCs and nanoemulsions of silica precursors formed under ethyl acetate buffered conditions. A dynamic rearrangement of the CTA(+)-oleate bilayer on the IONPC surfaces is proposed to be responsible for the templating process of the silica shells around the individual IONPs. In comparison to previously reported methods in the literature, our work provides a much more detailed experimental evidence of the silica-coating mechanism in a nanoemulsion system. Overall, ethyl acetate is proven to be a very efficient agent for an effortless preparation of monodispersed IONPs@acetate@SiO2 and hydrophilic Ac-IONPs from IONPCs.

  • 103.
    Khachatourian, Malek Adrine
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Iran University of Science and Technology, Iran.
    Golestani-Fard, F.
    Sarpoolaky, H.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vasileva, Elena
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Mensi, Mounir
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Microwave synthesis of Y2O3:Eu3+ nanophosphors: A study on the influence of dopant concentration and calcination temperature on structural and photoluminescence properties2016In: Journal of Luminescence, ISSN 0022-2313, E-ISSN 1872-7883, Vol. 169, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Red fluorescent emitting monodispersed spherical Y<inf>2</inf>O<inf>3</inf> nanophosphors with different Eu3+ doping concentrations (0-13 mol%) are synthesized by a novel microwave assisted urea precipitation, which is recognized as a green, fast and reproducible synthesis method. The effect of Eu3+ doping and calcination temperature on the structural characteristics and luminescence properties of particles is investigated in detail. The as prepared powders have (Y,Eu)(OH)(CO<inf>3</inf>) structure which converts to Y<inf>2</inf>O<inf>3</inf>:Eu3+ from 500 °C and become crystalline at higher temperatures. The crystallite size of nanophosphors increased from 15 nm to 25 nm as the calcination temperature increased from 700 °C to 1050 °C. The efficient incorporation of Eu3+ ions in cubic Y<inf>2</inf>O<inf>3</inf> host matrix is confirmed by the calculated X-ray Powder diffraction (XRPD) structural parameters. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs show that the as obtained and calcined particles are spherical, monodispersed and non-agglomerated. The overall size of particles increases from 61±8 nm to 86±9 nm by increasing Eu3+ concentration from 0 mol% to 13 mol%. High resolution TEM revealed polycrystalline nature of calcined particles. The particles exhibit a strong red emission under ultraviolet (UV) excitation. The photoluminescence (PL) intensity of the peaks increases proportionally with Eu3+ concentration and the calcination temperature with no luminescence quenching phenomenon observed even for Y<inf>2</inf>O<inf>3</inf>:13%Eu3+. The fluorescent emission properties combined with the monodispersity and narrow size distribution characteristics make the Y<inf>2</inf>O<inf>3</inf>:Eu3+ heavy metal free nanophosphors applicable in fluorescence cell imaging and as fluorescence biolabels.

  • 104.
    Khachatourian, Malek Adrine
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. IUST-Iran University of Science and Technology, Iran.
    Golestani-Fard, F.
    Sarpoolaky, H.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Zhao, Yichen
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Green synthesis of Y2O3:Eu3+ nanocrystals for bioimaging2015In: Materials Research Society Symposium Proceedings, Materials Research Society, 2015, Vol. 1720, p. 59-64Conference paper (Refereed)
    Abstract [en]

    Rare earth (e.g., Eu, Er, Yb, Tm) doped Y<inf>2</inf>O<inf>3</inf> nanocrystals are promising fluorescent bioimaging agents which can overcome well known problems of currently used organic dyes like photobleaching, phototoxicity, and light scattering. Furthermore, the alternative quantum dots (QDs) composed of heavy metals (e.g., CdSe) possess inherently low biocompatibility due to the heavy metal content. In the present work, monodisperse spherical Y<inf>2</inf>O<inf>3</inf>:Eu3+ nanocrystals were successfully synthesized by microwave assisted urea precipitation method followed by thermochemical treatment. This is a green, fast and reproducible synthesis method, which is surfactant and hazardous precursors free. The as prepared particles were non-aggregated, spherical particles with a narrow size distribution. The calcined particles have a polycrystalline structure preserving the monodispersity and the spherical morphology of the as prepared particles. After calcination of Y(OH)CO<inf>3</inf>:Eu3+ precursors at 900°C for 2 hours, a highly crystalline cubic Y<inf>2</inf>O<inf>3</inf> structure was obtained. The Y<inf>2</inf>O<inf>3</inf>:Eu3+ spherical particles showed a strong red emission peak at 613nm due to the 5D<inf>0</inf>-7F<inf>2</inf> forced electric dipole transition of Eu3+ ions under UV excitation (235 nm) as revealed by the photoluminescence analysis (PL). The effect of reaction time on size and photoluminescence properties of calcined particles and also the effect of reaction temperature and pressure on the size and the yield of the precipitation process have been studied. The intense red fluorescent emission, excellent stability and potential low toxicity make these QDs promising for applications in bio-related areas such as fluorescence cell imaging or fluorescence bio labels.

  • 105. Khan, A.
    et al.
    Toprak, Muhammet
    University of California at Santa Barbara, Chemistry Department.
    et al.,
    Holographic recording in cross-linked polymeric matrices through photoacid generation2008In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 20, no 11, p. 3669-3674Article in journal (Refereed)
    Abstract [en]

    We report a novel strategy for writing volume holograms by photoacid generation and subsequent acid-catalyzed degradation leading to increased free volume/refractive index modulation in the exposed regions of a cross-linked rigid polymeric matrix. This strategy offers nondestructive read out and high diffraction efficiency and allows optical-quality, millimeter thick films to be fabricated that possess excellent thermal and dimensional stability. A key feature of this approach is the efficient acid-catalyzed degradation of functional groups in the cross-linked matrix leading to release of volatile products which diffuse readily out of the thick films. Furthermore, the reported data storage material is lightweight and inexpensive and can be easily processed into different shapes, making it an attractive candidate for data storage applications.

  • 106.
    Khan, Abdullah
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Saleemi, Mohsin
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Johnsson, M.
    Han, L.
    Nong, N. V.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Fabrication, spark plasma consolidation, and thermoelectric evaluation of nanostructured CoSb32014In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 612, p. 293-300Article in journal (Refereed)
    Abstract [en]

    Nanostructured powders of thermoelectric (TE) CoSb3 compounds were synthesized using a chemical alloying method. This method involved co-precipitation of oxalate precursors in aqueous solution with controlled pH, followed by thermochemical treatments including calcination and reduction to produce stoichiometric nanostructured CoSb3. Moreover, CoSb3 nanoparticles were consolidated by spark plasma sintering (SPS) with a very brief processing time. Very high compaction densities (>95%) were achieved and the grain growth was almost negligible during consolidation. An iterative procedure was developed to maintain pre-consolidation particle size and to compensate Sb evaporation during reduction. Significant changes in particle size and morphology were observed, and the post-reduction cooling was found to be an important stage in the process. The spark plasma sintering (SPS) parameters were optimized to minimize the grain growth while achieving sufficient densification. Grain sizes in the range of 500 nm to 1 mu m, with compaction density of 95-98% were obtained. Preliminary measurements of thermal diffusivity and conductivity showed the dependence on grain size as well as on porosity. TE transport properties were measured in the temperature range of 300-650 K. Sample showed p-type behavior with a positive Seebeck coefficient, which increases with increasing temperature. Electrical conductivity measurements indicate metallic behavior and it decreases with increasing temperature. Thermal conductivity also decreases with increasing temperature and major contribution is due to the lattice component. A TE figure of merit of 0.15 was achieved for high purity CoSb3 nanostructured TE material at 650 K and these results are comparable with the values reported for the best unfilled/undoped CoSb3 in the literature.

  • 107.
    Kim, Do-Kyung
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Toprak, Muhammet S.
    KTH, Superseded Departments, Materials Science and Engineering.
    Mikhaylova, Maria
    KTH, Superseded Departments, Materials Science and Engineering.
    Jo, Yunsuk
    KTH, Superseded Departments, Materials Science and Engineering.
    Savage, S.J.
    Lee, H.B.
    Muhammed, M.
    Polymeric nanocomposites of complex ferrite2004In: Functional Nanomaterials For Optoelectronics And Other Applications / [ed] Lojkowski, W; Blizzard, JR, 2004, Vol. 99-100, p. 165-168Conference paper (Refereed)
    Abstract [en]

    The influence of mixtures of Ni0.5Zn0.4CU0.1Fe2O4, CoFe2O4, and graphite on the permeability, permittivity and microwave absorption properties in a composite embedded with insulating polymeric matrix, that can be used for X- and P-band radar absorption, has been investigated. Thermodynamic modelling of the complex ferrite system has been demonstrated by the controlled simultaneous coprecipitation of all ions inolved in the composite in the selected working pH ranges. The method employed is very convenient for the synthesis of multicomponent systems with a homogenous distribution of compositions.

  • 108. Kim, Se-Hoon
    et al.
    Kim, Min Cheol
    Kim, Min-Suk
    Ahn, Jong Pil
    Moon, Kyoung-Sook
    Koo, Sang Mo
    Tafti, Mohsen Y.
    Park, Joo-Seok
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Lee, Byung-Ha
    Kim, Do Kyung
    Nanophase oxalate precursors of thermoelectric CoSb3 by controlled coprecipitation predicted by thermodynamic modeling2016In: Advanced Powder Technology, ISSN 0921-8831, E-ISSN 1568-5527, Vol. 27, no 2, p. 773-778Article in journal (Refereed)
    Abstract [en]

    The precursors for the formation of thermoelectric skutterudite CoSb3 nanoparticles are predicted by thermodynamic modeling of the complex chemical species. Based on the results, equimolar mixture of CoC2O4 center dot 2H(2)O and Sb(C2O4) OH are successively co-precipitated under controlled conditions of pH = 2.7 and concentration of reactants. The as synthesized powder was decomposed at 350 degrees C to remove the organic molecules and further reduced to CoSb3 phase by heating at 530 degrees C under hydrogen flow. The obtained powder was consolidated by spark plasma sintering (SPS). CoSb3 prepared by controlled chemical co-precipitation has p-type behavior with a positive sign of the Seebeck coefficient. TE transport properties were measured, which revealed that the Seebeck coefficient increased 2.5 times with increasing the temperature and it is lower than the ball milled CoSb3. Thermal conductivity of sintered CoSb3 at 773 K starts from 0.06 W/cm K at room temperature and decreases to 0.04 W/cm K at 700 K, which is lower than the bulk counterpart. The ZT of coprecipitated CoSb3 and SPS consolidated at 773 K shows 2 times higher than the ball milled one. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

  • 109. Kodash, V. Y.
    et al.
    Groza, J. R.
    Aldica, G.
    Toprak, Muhammet
    Li, Shanghua
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Muhammed, Mamoun
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Field-activated sintering of skutterudites2007In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 57, no 6, p. 509-511Article in journal (Refereed)
    Abstract [en]

    Skutterudite (Co0.92Ni0.08)4Sb11.88Te0.12 powder has been consolidated under an applied electrical field using a field-assisted sintering technique (FAST). The low FAST sintering temperature and relatively high heating rate considerably reduce grain growth during sintering.

  • 110. Koseoglu, Y
    et al.
    Aktas, B
    Yildiz, F
    Kim, DK
    Toprak, Muhammet S.
    KTH, Superseded Departments, Materials Science and Engineering.
    Muhammed, Mamoun
    KTH, Superseded Departments, Materials Science and Engineering.
    ESR studies on high-T-c superconductor MgB22003In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 390, no 3, p. 197-203Article in journal (Refereed)
    Abstract [en]

    MgB2, a high-T-c superconductor, has been studied by electron spin resonance (ESR) techniques at the temperature range of 7-300 K. Polycrystalline powders consisting of MgB2, MgO and MgB4 phases were diluted and oriented in paraffin by applying an external magnetic field of 15 kG. A very narrow (2.5 G), strong, and isotropic signal that corresponded to almost free electron g-values was observed at all temperatures. Both the signal intensity and line width were observed to exhibit strong temperature dependence below T-c. The intensity of the ESR spectra, which corresponds to dc susceptibility, generally obeys the Curie law in this temperature range; However, some critical temperatures (approximately 215, 190, 150, and 39 K) were evident from both intensity and line width curves. While the ESR line is strongly broadened, the signal intensity significantly start to increase just below T = 39 K (corresponding to a transition temperature from normal to superconducting state), passes through a broad maximum around 30 K and then shows a sharp decrease as the temperature is decreased further. The origins of the minor changes both in the intensity and the line width curves at other (higher) critical temperatures are not clear yet. In fact, the change at 215 K was observed to be meta-stable. These minor changes might be taken as signs for changes of local crystalline field symmetry around weakly localized conduction electrons or holes, which are the sources of the ESR signal.

  • 111. Koseoglu, Y
    et al.
    Yildiz, F
    Salazar-Alvarez, G
    Toprak, Muhammet S.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Muhammed, Mamoun
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Aktas, B
    Synthesis, characterization and ESR measurements of CoNiO nanoparticles2005In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 242, no 8, p. 1712-1718Article in journal (Refereed)
    Abstract [en]

    Powders of cobalt core with a nickel (11) oxide shell (CoNiO) have been studied by Electron Spin Resonance (ESR) technique in the temperature range of 10-300 K. A strong and broad (1300 G) single ESR peak in X-, K- and Q-band spectra has been observed at all the temperature ranges. While the resonance field remains almost constant, both the ESR line intensity and the line width were seen to increase first slowly down to T-c = 160 K. And then both the resonance field and the ESR signal intensity decrease and the line width increase with decreasing temperature. Below T. the intensity smoothly decrease down to 10 K. This kind of behavior is attributed to a typical spin-glass like behavior. Some small and relatively smooth changes at about 60 K, 90 K, 210 K, and 250 K are appeared as well. A linear dependence of resonance field to microwave frequency is observed at room temperatures and the effective g-value and internal field are theoretically found as 2,17 and 90 G, respectively. The experimental data indicate a very strong spin disorder (spin frustration) due to antiferromagnetic exchange interactions among the spins. This is attributed to the D-M anisotropy on the particle surfaces that it is expected to enhance due to increment of surface-to-volume ratio.

  • 112. Krajnik, P.
    et al.
    Muhammed, M.
    Nikkam, Nader
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Rashid, A.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Heat exchange fluid comprising layered structured particles in a base liquid, method of preparation thereof and its application: Värmeväxlarvätskan innehållande skikt-strukturerade partiklar i en basvätska, metod för framställning därav och dess tillämpning2012Patent (Other (popular science, discussion, etc.))
  • 113.
    Krajnik, Peter
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Rashid, Amir
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Pusavec, Franci
    Remskar, Maja
    Yui, Akinori
    Nikkam, Nader
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Transitioning to sustainable production - part III: developments and possibilities for integration of nanotechnology into material processing technologies2016In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 112, p. 1156-1164Article in journal (Refereed)
    Abstract [en]

    A nanoparticle-based cooling-lubricating fluid (nCLF), designed and fabricated by suspending engineered nanoparticles (ENPs) in biodegradable vegetable-based fluids, has been developed for integration into material processing technologies. This new product exhibits tribological properties superior to those of conventional metalworking fluids. The major innovation is the ability to create a stable nCLF through the modification of ENP surfaces. Functionalized MoS2 nanotube ENPs were successful used as low friction additives. The experimental work, required for the proof-of-concept and technology validation, was carried out on three different levels to quantify the improved tribological behavior of nCLF. These experiments include standard tribological tests, mock-up tests to simulate machining, and actual machining tests. It is demonstrated that the specific properties of ENPs, fluid design and composition, as well as specific lubrication mechanisms, exhibit superior performance of nCLF in terms of friction and wear. The objective of this paper is to demonstrate how recent nanotechnology developments support innovation needed for transitioning to sustainable production via new product development and integrated industrial applications.

  • 114.
    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, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Feliu, Neus
    Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Gabrielsson, Susanne
    Clinical Allergy Research Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, 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, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, 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 cells2011In: Toxicology and Applied Pharmacology, ISSN 0041-008X, E-ISSN 1096-0333, Vol. 253, no 2, p. 81-93Article in journal (Refereed)
    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.

  • 115. Kurtan, U.
    et al.
    Amir, Md.
    Baykal, A.
    Sozeri, H.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Magnetically Recyclable Fe3O4@His@Cu Nanocatalyst for Degradation of Azo Dyes2016In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 16, no 3, p. 2548-2556Article in journal (Refereed)
    Abstract [en]

    Fe3O4@His@Cu magnetic recyclable nanocatalyst (MRCs) was synthesized by reflux method using L-histidine as linker. The composition, structure and magnetic property of the product were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Fourier Transform infrared spectroscopy (FT-IR) and vibrating sample magnetometry (VSM). Powder XRD, FTIR and EDAX results confirmed that the as-synthesized products has Fe3O4 with spinel structure and Cu nanoparticles with moderate crystallinity without any other impurities. The surface of the Fe3O4@His nanocomposite was covered by tiny Cu nanoparticles. We examine the catalytic activity of Fe3O4@His@Cu MRCs for the degradation of two azo dyes, methyl orange (MO) and methylene blue (MB) as well as their mixture. The reusability of the nanocatalyst was good and sustained even after 3 cycles. Therefore this innovated Fe3O4@His@Cu MRCs has a potential to be used for purification of waste water.

  • 116. Kurtan, U.
    et al.
    Dursun, D.
    Aydin, H.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Baykal, A.
    Bozkurt, A.
    Influence of calcination rate on morphologies and magnetic properties of MnFe2O4 nanofibers2016In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 42, no 16, p. 18189-18195Article in journal (Refereed)
    Abstract [en]

    In the present study, we succesfully synthesized electrospun MnFe2O4 nanofibers (NFs) from poly(N-vinylpyrrolidone)/manganese(II) nitrate composite by electrospinning and then as-spun NFs were calcined 450 degrees C for 2 h in air atmosphere to remove the polymer matrix and fabricate inorganic MnFe2O4 nanofibers. In order to investigate the sintering behavior of MnFe2O4 nanofibers in air atmosphere, the synthesized as-spun nanofibers were calcined with different calcination rates. Thus the effect of calcination rate on structure and morphology of nanofibers were discussed clearly. The structural, magnetic, morphological, spectroscopic and thermal characterizations were also done by XRD, VSM, TEM, SEM, FTIR and TG analysis. In the presence of slow calcination rate, only peaks of MnFe2O4 could be observed on other hand in the presence of rapid calcination rate, formation of an impurity was observed. Scanning electron microscope images revealed that MnFe2O4 nanorods possess a broader range size distribution with higher particle size. Also, magnetic properties were both size and shape dependent.

  • 117. Kurtan, U.
    et al.
    Topkaya, R.
    Baykal, A.
    Toprak, M. S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Temperature dependent magnetic properties of CoFe2O4/CTAB nanocomposite synthesized by sol gel auto-combustion technique2013In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 39, no 6, p. 6551-6558Article in journal (Refereed)
    Abstract [en]

    A CoFe2O4/cetyl trimethylammonium bromide (CTAB) nanocomposite has been fabricated by a sol gel auto-combustion method. Characterization of the material revealed the composition of the crystalline phase as CoFe2O4 while FT-IR confirmed the presence of CTAB on the nanoparticles. From X-ray line profile fitting, average crystallite size was estimated to be 22 +/- 6 nm. SEM analysis showed a porous sheet-like morphology with internal nanosize grains of about 30 nm. The room temperature coercive field (He) of the CoFe2O4/CTAB nanocomposite was found to be 1045 Oe which is close to the previously reported room temperature values for bulk CoFe2O4. The H-c, was observed to decrease almost linearly with the square root of the temperature (root T) according to Kneller's law. From the linear fit of H-c versus root T, the zero-temperature coercivity (H-c0) and superparamagnetic blocking temperature (T-B) of the CoFe2O4/CTAB nanocomposite were found to be similar to 9.1 kOe and similar to 425 K, respectively. The remanence magnetization (M-r), the reduced remanent magnetization (M-r/M-s), and the effective magnetic anisotropy (K-eff) decrease with increasing temperature. The M-r/M-s value of 0.6 at 10 K higher than the theoretical value of 0.5 for non-interacting single domain particles with the easy axis randomly oriented suggests the CoFe2O4/CTAB nanocomposite to have cubic magnetocrystalline anisotropy according to the Stoner Wohlfarth model.

  • 118.
    Larsson, Jakob C.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vågberg, William
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Toprak, Muhammet
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Dzieran, Johanna
    Arsenian-Henriksson, Marie
    Hertz, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    High-spatial-resolution x-ray fluorescence tomography with spectrally matched nanoparticles2018In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 63, p. 164001-Article in journal (Refereed)
    Abstract [en]

    Present macroscopic biomedical imaging methods provide either morphology with high spatial resolution (e.g. CT) or functional/molecular information with lower resolution (e.g. PET). X-ray fluorescence (XRF) from targeted nanoparticles allows molecular or functional imaging but sensitivity has so far been insufficient resulting in low spatial resolution, despite long exposure times and high dose. In the present paper, we show that laboratory XRF tomography with metal-core nanoparticles (NPs) provides a path to functional/molecular biomedical imaging with ~100 µm resolution in living rodents. The high sensitivity and resolution rely on the combination of a high-brightness liquid-metal-jet x-ray source, pencil-beam optics, photon-counting energy-dispersive detection, and spectrally matched NPs. The method is demonstrated on mice for 3D tumor imaging via passive targeting of in-house-fabricated molybdenum NPs. Exposure times, nanoparticle dose, and radiation dose agree well with in vivo imaging.

  • 119.
    Li, Shanghua
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Furberg, Richard
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Nature-inspired boiling enhancement by novel nanostructured macroporous surfaces2008In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 18, no 15, p. 2215-2220Article in journal (Refereed)
    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.

  • 120.
    Li, Shanghua
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Furberg, Richard
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Toprak, Muhammet
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Zhang, Yu
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Fabrication of nanostructured micro-porous surfaces for enhanced boilingManuscript (Other academic)
  • 121.
    Li, Shanghua
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    He, Zeming
    Institute of Materials Research, German Aerospace Center (DLR).
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Stiewe, Christian
    Institute of Materials Research, German Aerospace Center (DLR).
    Müller, Eckhard
    Institute of Materials Research, German Aerospace Center (DLR).
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Thermoelectric properties of CoSb3 with maize-like structure2007In: Physica Status Solidi-Rapid Research Letter, ISSN 1862-6254, Vol. 1, no 6, p. 259-261Article in journal (Refereed)
    Abstract [en]

    Maize-like CoSb3 powders were obtained via the chemical alloying method. After the consolidation of the nanopowder using hot press, the CoSb3 compact shows a higher Seebeck coefficient and lower thermal conductivity. For the investigated CoSb3, a ZT of 0.15 at 673 K is shown. Though the achieved ZT does not reach the optimal value (0. 17 to 0. 18) for pure CoSb3, due to its lower electrical conductivity, the novel structure fabrication provides an interesting and promising approach to enhancing the thermoelectric performance.

  • 122.
    Li, Shanghua
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Liang, Yibin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Qin, Jian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Template electrodeposition of ordered bismuth telluride nanowire arrays2009In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 9, no 2, p. 1543-1547Article in journal (Refereed)
    Abstract [en]

    Thermoelectric bismuth telluride nanowire arrays have been synthesized by direct-current electrodeposition into porous anodic alumina membranes both galvanostatically and potentiostatically. The as-synthesized Bi2Te3 nanowire arrays are highly ordered in large area, stoichiometric, uniform, with high aspect ratio (above 100) and high filling ratio (>90%) of the membrane. The effects of different electrochemical deposition parameters on crystal structures, morphology and composition have been investigated. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) have been used to characterize the physical and chemical properties of the nanowires.

  • 123.
    Li, Shanghua
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Meng Lin, Meng
    Toprak, Muhammet S
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Kim, Do Kyung
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Nanocomposites of polymer and inorganic nanoparticles for optical and magnetic applications2010In: Nano reviews, ISSN 2000-5121, Vol. 1, p. 5214-Article in journal (Refereed)
    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.

  • 124.
    Li, Shanghua
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Qin, Jian
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Fornara, Andrea
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Kim, Do Kyung
    Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites2009In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 20, no 18Article in journal (Refereed)
    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.

  • 125.
    Li, Shanghua
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Soliman, Hesham M. A.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Zhou, Jian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Platzek, Dieter
    Ziolkowski, Pawel
    Müller, Eckhard
    Effects of annealing and doping on nanostructured bismuth telluride thick films2008In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 20, no 13, p. 4403-4410Article in journal (Refereed)
    Abstract [en]

    Bismuth telluride is the state-of-the-art thermoelectric (TE) material for cooling applications with a figure of merit of ∼1 at 300 K. There is a need for the development of TE materials based on the concept of thick films for miniaturized devices due to mechanical and manufacturing constraints for the thermoelement dimensions. We reported earlier a method for the fabrication of high-quality nanostructured bismuth telluride thick films with thickness from 100 to 350 μm based on electrochemical deposition techniques. In this paper, annealing is performed to further improve the TE performance of the nanostructured bismuth telluride thick films and n/p-type solid solutions are successfully fabricated by doping Se and Sb, respectively. The conditions for both annealing and doping for the thick films are investigated, and the effects of annealing and doping on morphology, crystalline phase, grain size, Seebeck coefficient, homogeneity, electrical conductivity, and power factor of the bismuth telluride thick films have been studied.

  • 126.
    Li, Shanghua
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Toprak, Muhammet
    Jo, Yun-Suk
    Kim, Do-Kyung
    Muhammed, Mamoun
    Bulk transparent and homogeneous PMMA-ZnO hybrid materials for UV-shelteringArticle in journal (Refereed)
  • 127.
    Li, Shanghua
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Toprak, Muhammet
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jo, Yun-Suk
    Kim, Do-Kyung
    Muhammed, Mamoun
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Fabrication of transparent polymer-inorganic hybrid material2005In: Materials Research Society Symposium Proceedings, 2005, Vol. R, no 45, p. 190-194Conference paper (Refereed)
    Abstract [en]

    Polymer-inorganic hybrid materials composed of polymethyl methacrylate (PMMA) and zinc compounds were prepared by sol-gel in-situ transition polymerization of zinc complex in PMMA matrix. Zinc acetate dihydrate dissolved in ethanol was used as the inorganic precursor. Monoethanolamine (MEA) acted as a complexing agent to control the hydrolysis of zinc acetate to produce a zinc compound network, and then PMMA, formed in-situ through a radical polymerization, were chemically bonded to the forming zinc compound network to realize a hybrid material. Transparent homogenous hybrid materials with slight colours from pink to yellow were fabricated by varying the composition. TEM, FT-IR were employed to investigate structural and physical properties. The UV-shielding effect was evaluated by UV-VIS. The low content of zinc (around 0.02 wt%) and the fine particle size rendered it visibly transparent and capable of greatly attenuating UV radiation in the full UV range.

  • 128. Li, Shanghua
    et al.
    Toprak, Muhammet S.
    Jo, Yun Suk
    Dobson, Jon
    Kim, Do Kyung
    Muhammed, Mamoun
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Bulk synthesis of transparent and homogeneous polymeric hybrid materials with ZnO quantum dots and PMMA2007In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 19, no 24, p. 4347-+Article in journal (Refereed)
    Abstract [en]

    [GRAPHICS] In situ sol-gel polymerization is demonstrated for fabricating transparent poly(methyl methacrylate) (PMMA)-ZnO quantum dot (QD)-hybrid materials in bulk dimension. ne transparent PMMA-ZnO QD hybrid materials exhibit enhanced UV-shielding effects in the entire UV range, even at concentrations as low as 0.02 wt %.

  • 129.
    Li, Shanghua
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Toprak, Muhammet S.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Soliman, Hesham M. A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Zhou, Jian
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Muhammed, Mamoun
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Platzek, Dieter
    Institute of Materials Research, German Aerospace Center (DLR).
    Müller, Eckhard
    Institute of Materials Research, German Aerospace Center (DLR).
    Fabrication of nanostructured thermoelectric bismuth telluride thick films by electrochemical deposition2006In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 18, no 16, p. 3627-3633Article in journal (Refereed)
    Abstract [en]

    Bismuth telluride ( Bi2Te3)-based solid solutions are state-of-the-art thermoelectric (TE) materials for cooling applications at room temperature with a high figure of merit ZT. Nanostructured TE bismuth telluride thick films have been fabricated by electrodeposition from a solution containing bismuth nitrate and tellurium dioxide in 1 M nitric acid onto gold-sputtered aluminum substrates. A conventional three-electrode cell was used with a platinum sheet as the counter electrode and a saturated calomel electrode (SCE) as the reference electrode. Ethylene glycol (EG) was added to the electrolyte in order to increase the thickness of the deposited films, and its effect on the structure, morphology, and compositional stoichiometry of the deposited film was investigated. SEM and XRD were used for structural and compositional characterization. Bismuth telluride films with thicknesses of ca. 350 mu m, a stoichiometric composition of Bi2Te3, and a hexagonal crystal structure were obtained. A microprobe technique was used to measure the lateral Seebeck coefficient in several samples. The free-standing films were shown to be of high homogeneity, where the abundance distribution of the Seebeck coefficient showed a half width of less than 1 mu V K-1 and a high electrical conductivity of around 450 S cm(-1) at room temperature.

  • 130.
    Li, Shanghua
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Zhang, Shuo
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    He, Zeming
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Stiewe, Christian
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Mueller, Eckhard
    Novel Solution Route Synthesis of Low Thermal Conductivity Nanocrystalline Bismuth Telluride2010In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 10, no 11, p. 7658-7662Article in journal (Refereed)
    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.

  • 131.
    Lobov, G. S.
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Marinins, A.
    KTH, School of Information and Communication Technology (ICT).
    Etcheverry, S.
    Zhao, Yichen
    KTH, School of Information and Communication Technology (ICT).
    Vasileva, Elena
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Sugunan, A.
    Laurell, F.
    Thylén, Lars
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Wosinski, L.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT).
    Toprak, M. S.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Direct birefringence and transmission modulation via dynamic alignment of P3HT nanofibers in an advanced opto-fluidic component2017In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 7, no 1, p. 52-61Article in journal (Refereed)
    Abstract [en]

    Poly-3-hexylthiophene (P3HT) nanofibers are semiconducting high-aspect ratio nanostructures with anisotropic absorption and birefringence properties found at different regions of the optical spectrum. In addition, P3HT nanofibers possess an ability to be aligned by an external electric field, while being dispersed in a liquid. In this manuscript we show that such collective ordering of nanofibers, similar to liquid crystal material, significantly changes the properties of transmitted light. With a specially fabricated opto-fluidic component, we monitored the phase and transmission modulation of light propagating through the solution of P3HT nanofibers, being placed in the electric field with strength up to 0.1 V/μm. This report describes a technique for light modulation, which can be implemented in optical fiber-based devices or on-chip integrated components.

  • 132.
    Lobov, Gleb S.
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Zhao, Yichen
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Marinins, Aleksandrs
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Li, Jiantong
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Sugunan, Abhilash
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Thylen, Lars
    KTH, School of Biotechnology (BIO).
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Ostling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Size Impact of Ordered P3HT Nanofibers on Optical Anisotropy2016In: Macromolecular Chemistry and Physics, ISSN 1022-1352, E-ISSN 1521-3935, Vol. 217, no 9, p. 1089-1095Article in journal (Refereed)
    Abstract [en]

    Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline structures with semiconductor properties. When P3HT nanofi bers are dispersed in nonconducting solvent, they react to external alternate electric field by aligning along the field lines. This can be used to create layers of ordered nanofi bers and is referred to as alternating current poling method. P3HT nanofi bers with three different size distributions are fabricated, using self-assembly mechanism in marginal solvents, and used for the alignment studies. Anisotropic absorption of oriented 2 mu m long nanofi bers exponentially increases with the magnitude of applied field to a certain asymptotic limit at 0.8 V mu m(-1), while 100-500 nm long nanofi bers respond to electric field negligibly. Effective optical birefringence of oriented 2 mu m long nanofi bers is calculated, based on the phase shift at 633 nm and the average layer thickness, to be 0.41. These results combined with further studies on real-time control over orientation of P3HT nanofi bers in liquid solution or host system are promising in terms of exploiting them in electroabsorptive and electrorefractive applications.

  • 133.
    Lobov, Gleb S.
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Zhao, Yichen
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Marinins, Aleksandrs
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Li, Jiantong
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Sugunan, A.
    Thylén, Lars
    KTH, School of Biotechnology (BIO). Hewlett-Packard Laboratories, United States.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT).
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Electric field induced optical anisotropy of P3HT nanofibers in a liquid solution2015In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 5, no 11, p. 2642-2647Article in journal (Refereed)
    Abstract [en]

    The nanofiber morphology of regioregular Poly-3- hexylthiophene (P3HT) is a 1D crystalline structure organized by π - π stacking of the backbone chains. In this study, we report the impact of electric field on the orientation and optical properties of P3HT nanofibers dispersed in liquid solution. We demonstrate that alternating electric field aligns nanofibers, whereas static electric field forces them to migrate towards the cathode. The alignment of nanofibers introduces anisotropic optical properties, which can be dynamically manipulated until the solvent has evaporated. Time resolved spectroscopic measurements revealed that the electro-optical response time decreases significantly with the magnitude of applied electric field. Thus, for electric field 1.3 V ·μm-1 the response time was measured as low as 20 ms, while for 0.65 V ·μm-1 it was 110-150 ms. Observed phenomenon is the first mention of P3HT supramolecules associated with electrooptical effect. Proposed method provides real time control over the orientation of nanofibers, which is a starting point for a novel practical implementation. With further development P3HT nanofibers can be used individually as an anisotropic solution or as an active component in a guest-host system.

  • 134.
    Lobov, Gleb S.
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Zhao, Yichen
    KTH, School of Information and Communication Technology (ICT).
    Marinins, Aleksandrs
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Li, Jiantong
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Sugunan, A.
    Thylen, Lars
    KTH, School of Biotechnology (BIO).
    Wosinski, L.ech
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Fotonik och mikrovågsteknik, FMI.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Popov, Sergei Yu
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Electro-optical response of P3HT nanofibers in liquid solution2015In: Asia Communications and Photonics Conference, ACPC 2015, 2015Conference paper (Refereed)
    Abstract [en]

    AC electric poling introduces in P3HT nanofibers anisotropic electro-optical response and birefringence. Along with birefringence, such material exhibits strong amplitude modulation which makes it more efficient alternative to liquid crystals. © 2015 OSA.

  • 135.
    Lobov, Gleb
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Zhao, Yichen
    KTH, School of Information and Communication Technology (ICT).
    Marinins, Aleksandrs
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Li, Jiantong
    KTH, School of Information and Communication Technology (ICT).
    Sugunan, A.
    Thylén, Lars
    KTH, School of Biotechnology (BIO). Hewlett-Packard Laboratories, United States.
    Wosinski, L.ech
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Photonics and Microwave Engineering , FMI.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Dynamic Manipulation of Optical Anisotropy of Suspended Poly-3-hexylthiophene Nanofibers2016In: Advanced Optical Materials, ISSN 2195-1071, Vol. 4, no 10, p. 1651-1656Article in journal (Refereed)
    Abstract [en]

    Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline semiconducting nanostructures, which are known for their application in photovoltaics. Due to the internal arrangement, P3HT nanofibers possess optical anisotropy, which can be enhanced on a macroscale if nanofibers are aligned. Alternating electric field, applied to a solution with dispersed nanofibers, causes their alignment and serves as a method to produce solid layers with ordered nanofibers. The transmission ellipsometry measurements demonstrate the dichroic absorption and birefringence of ordered nanofibers in a wide spectral range of 400–1700 nm. Moreover, the length of nanofibers has a crucial impact on their degree of alignment. Using electric birefringence technique, it is shown that external electric field applied to the solution with P3HT nanofibers can cause direct birefringence modulation. Dynamic alignment of dispersed nanofibers changes the refractive index of the solution and, therefore, the polarization of transmitted light. A reversible reorientation of nanofibers is organized by using a quadrupole configuration of poling electrodes. With further development, the described method can be used in the area of active optical fiber components, lab-on-chip or sensors. It also reveals the potential of 1D conducting polymeric structures as objects whose highly anisotropic properties can be implemented in electro-optical applications.​

  • 136.
    Ma, Ying
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Wang, Xiaodi
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Li, Shanghua
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Samarium-doped ceria nanowires: Novel synthesis and application in low-temperature solid oxide fuel cells2010In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 22, no 14, p. 1640-1644Article in journal (Refereed)
    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.

  • 137.
    Ma, Ying
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Wang, Xiaodi
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    A surfactant and template-free route for controlled synthesis of hierarchically structured cerium oxides with tunable morphologies and their application for water treatmentArticle in journal (Other academic)
  • 138.
    Malek Khachatourian, Adrine
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM. Iran University of Science and Technology, Iran .
    Golestani-Fard, Farhad
    Sarpoolaky, Hossein
    Vogt, Carmen
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Microwave assisted synthesis of monodispersed Y2O3 and Y2O3:Eu3+ particles2015In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 41, no 2, p. 2006-2014Article in journal (Refereed)
    Abstract [en]

    Monodisperse spherical Y2O3 and Y2O3:Eu3+ nanocrystalline particles with particle size between 100 nm and 350 nm were successfully prepared by microwave assisted urea precipitation method followed by a thermochemical treatment. Fast microwave heating, controlled decomposition of urea and burst nucleation of metal ions in aqueous solution led to the formation of non-aggregated spherical particles with narrow size dispersion. The particle size and size dispersion was controlled by adjusting the urea/metal ions ratio, the metal ions concentration, the reaction time and the temperature. X-ray diffraction (XRD) analysis indicated that the as prepared particles have Y(OH)CO3 composition, which converted to highly crystalline cubic Y2O3 after calcination at temperatures above 600 degrees C. The calcined Y2O3 particles preserved the spherical morphology of the as prepared particles and exhibited polycrystalline structure. The size of the crystallites increased from similar to 8 nm to similar to 37 nm with the increase of the calcination temperature from 500 degrees C to 900 degrees C. In order to transform these nanostructures to luminescent composition, Eu3+ doping has been performed. Y2O3:Eu3+ particles inherited the morphology and polycrystalline structure of the host Y2O3 particles. Photoluminescence (PL) analysis of Y2O3:Eu3+ particles showed a strong red emission peak at 613 nm corresponding to D-5(0)-F-7(2) forced electric dipole transition of Eu3+ ions under UV excitation. All these critical characteristics, and being heavy-metal free, make these particles useful for bioimaging, and display devices.

  • 139.
    Mikhaylova, Maria
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Kim, Do-Kyung
    KTH, Superseded Departments, Materials Science and Engineering.
    Berry, CC
    Zagorodni, Andrei
    KTH, Superseded Departments, Materials Science and Engineering.
    Toprak, Muhammet S.
    KTH, Superseded Departments, Materials Science and Engineering.
    Curtis, ASG
    Muhammed, Mamoun
    KTH, Superseded Departments, Materials Science and Engineering.
    BSA immobilization on amine-functionalized superparamagnetic iron oxide nanoparticles2004In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 16, no 12, p. 2344-2354Article in journal (Refereed)
    Abstract [en]

    Immobilization of bovine serum albumin (BSA) on surface-modified superparamagnetic iron oxide nanoparticles (SPION) has been performed by two different double-step immobilization approaches. The first approach consists of preparation of SPION by controlled chemical coprecipitation in the presence of BSA solution, whereas the second approach includes preliminary surface modification of SPION with an amine group using a coupling agent of 3-aminepropyltrimethoxysilane (APTMS). Both procedures are followed by 1-ethyl-3-(3-dimethylaminepropyl) carbodiimide hydrochloride (EDC) activation with sequential immobilization of the layer of BSA. Additionally, an attempt to modify the surface of SPION with amine and carboxylic groups is undertaken by using L-aspartic acid (LAA). TEM shows that the particle size varies in the range 10-15 nm and does not change significantly after the coating process. The presence of BSA and amine groups on the surface of SPION is confirmed by FT-IR. Magnetic properties are investigated by VSM and results indicate that the superparamagnetic properties are retained for BSA-coated SPION while reducing the value of saturation magnetization (M-s). The binding capacity is estimated from thermo-gravimetric and chemical analyse;. APTMS-coated SPION show higher BSA binding capacity compared to that of coprecipitated SPION in the presence of BSA. In vitro tests have been performed after the functionalization of SPION with LAA and BSA. Human dermal fibroblasts are incubated with the surface-modified SPION for 6 and 24 h to observe cell behavior, morphology, cytoskeletal organization, and interactions between cell and SPION. BSA-coated SPION incubated with cells demonstrated a cell response similar to that of control cells, with no adverse cell damage and no endocytosis, whereas LAA-coated SPION show partial endocytosis without cytoskeletal disorganization.

  • 140.
    Mohamed, A.
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Cairo University, Egypt; Akhbar El Yom Academy, Egypt.
    Yousef, S.
    Ali Abdelnaby, M.
    Osman, T. A.
    Hamawandi, Bejan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Alexandria University, Egypt.
    Uheida, Abdusalam
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Photocatalytic degradation of organic dyes and enhanced mechanical properties of PAN/CNTs composite nanofibers2017In: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 182, p. 219-223Article in journal (Refereed)
    Abstract [en]

    This work describes the enhanced mechanical properties of the composite nanofibers and the photodegradation of two organic dyes using PAN/CNTs under UV irradiation at different volume concentration (0.05, 0.1, 0.2, and 0.3 wt.%). The composite nanofibers was performed with polyacrylonitrile (PAN), and carbon nanotubes (CNTs) by electrospinning process. The composite nanofibers structure and morphology is characterized by XRD, FTIR, SEM, and TEM. The result indicates that with increasing CNTs content, the mechanical properties of the composite nanofibers was enhanced, and became more elastic, and the elastic modulus increased drastically. The results of mechanical properties exhibit improvements in tensile strengths, and elastic modulus by 38% and 84% respectively, at only 0.05 wt.% CNTs. Moreover, photocatalytic degradation performance in short time and low power intensity was achieved comparison to earlier reports.

  • 141.
    Mohamed, Alaa
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM. Mechanical Design and Production Engineering Department, Cairo University, Giza, Egypt.
    El-Sayed, R.
    Osman, T. A.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Muhammed, Mamoun A.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Uheida, Abdusalam
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Composite nanofibers for highly efficient photocatalytic degradation of organic dyes from contaminated water2016In: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 145, p. 18-25Article in journal (Refereed)
    Abstract [en]

    In this study highly efficient photocatalyst based on composite nanofibers containing polyacrylonitrile (PAN), carbon nanotubes (CNT), and surface functionalized TiO2 nanoparticles was developed. The composite nanofibers were fabricated using electrospinning technique followed by chemical crosslinking. The surface modification and morphology changes of the fabricated composite nanofibers were examined through SEM, TEM, and FTIR analysis. The photocatalytic performance of the composite nanofibers for the degradation of model molecules, methylene blue and indigo carmine, under UV irradiation in aqueous solutions was investigated. The results demonstrated that high photodegradation efficiency was obtained in a short time and at low power intensity compared to other reported studies. The effective factors on the degradation of the dyes, such as the amount of catalyst, solution pH and irradiation time were investigated. The experimental kinetic data were fitted using pseudo-first order model. The effect of the composite nanofibers as individual components on the degradation efficiency of MB and IC was evaluated in order to understand the overall photodegradation mechanism. The results obtained showed that all the components possess significant effect on the photodegradation activity of the composite nanofibers. The stability studies demonstrated that the photodegradation efficiency can remain constant at the level of 99% after five consecutive cycles.

  • 142.
    Mohamed, Alaa
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Akhbar El Yom Academy, Egypt.
    Osman, T. A.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Yilmaz, E.
    Uheida, Abdusalam
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Visible light photocatalytic reduction of Cr(VI) by surface modified CNT/titanium dioxide composites nanofibers2016In: Journal of Molecular Catalysis A: Chemical, ISSN 1381-1169, E-ISSN 1873-314X, Vol. 424, p. 45-53Article in journal (Refereed)
    Abstract [en]

    In this work we report a highly efficient photocatalytic reduction of Cr(VI) based on PAN-CNT/TiO2-NH2 composite nanofibers fabricated by using electrospinning technique followed by chemical crosslinking of surface modified TiO2 NPs functionalized with amino group. The structure and morphology of the fabricated composite nanofibers were characterized by FTIR, SEM, TEM, TGA, and XPS. The results indicate that the composite nanofibers possess excellent photoreduction performance for Cr(VI) under visible light (125 W) after 30 min, which is much faster than previous reports. The effects of various experimental parameters such as catalyst dose, irradiation time, initial concentration of Cr(VI), and pH on the photoreduction efficiency of Cr(VI) were investigated. The highest photoreduction efficiency of Cr (VI) was obtained at low acidity and low amount of TiO2/CNT photocatalyst. The kinetic experimental data was attained and fitted well with a pseudo-first-order model. The UV–vis spectrophotometer and XPS analyses proved that chromate Cr(VI) was reduced to Cr(III). In addition, it can be concluded that the addition of the phenol enhances the photocatalytic reduction of Cr(VI). Furthermore, the photoreduction mechanism has also been discussed. Finally, the fabricated composite nanofibers were found to be stable after at least five regeneration cycles.

  • 143. Mohamed, Alaa
    et al.
    Osman, T. A.
    Toprak, Muhammet Sadaka
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Uheida, Abdusalam
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Surface functionalized composite nanofibers for efficient removal of arsenic from aqueous solutions2017In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 180, p. 108-116Article in journal (Refereed)
    Abstract [en]

    A novel composites nanofiber was synthesized based on PAN-CNT/TiO2-NH2 nanofibers using electrospinning technique followed by chemical modification of TiO2 NPs. PAN-CNT/TiO2-NH2 nanofiber were characterized by XRD, FTIR, SEM, and TEM. The effects of various experimental parameters such as initial concentration, contact time, and solution pH on As removal were investigated. The maximum adsorption capacity at pH 2 for As(III) and As(V) is 251 mg/g and 249 mg/g, respectively, which is much higher than most of the reported adsorbents. The adsorption equilibrium reached within 20 and 60 min as the initial solution concentration increased from 10 to 100 mg/L, and the data fitted well using the linear and nonlinear pseudo first and second order model. Isotherm data fitted well to the linear and nonlinear Langmuir, Freundlich, and Redlich-Peterson isotherm adsorption model. Desorption results showed that the adsorption capacity can remain up to 70% after 5 times usage. This work provides a simple and an efficient method for removing arsenic from aqueous solution.

  • 144.
    Morteza, Ghanbarpourgeravi
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Nader, Nikkam
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Toprak, Mohammet S
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Muhammed, Mamoun Ali
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Thermal performance of screen mesh heat pipe with Al2O3 nanofluid2015In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 66, p. 213-220Article in journal (Refereed)
    Abstract [en]

    This study presents the effect of Al2O3 nanofluid (NF) on thermal performance of screen mesh heat pipe in cooling applications. Three cylindrical copper heat pipes of 200 mm length and 6.35 mm outer diameter containing two layers of screen mesh were fabricated and tested with distilled water and water based Al2O3 NF with mass concentrations of 5% and 10% as working fluids. To study the effect of NF on the heat pipes thermal performance, the heat input is increased and then decreased consecutively and the heat pipes surface temperatures are measured at steady state conditions. Results show that using 5 wt.% of Al2O3 NF improves the thermal performance of the heat pipe for increasing and decreasing heat fluxes compared with distilled water, while utilizing 10 wt.% of Al2O3 NF deteriorates the heat pipe thermal performance. For heat pipe with 5 wt.% Al2O3 NF the reduction in thermal resistance of the heat pipe is found to be between 6% and 24% for increasing and between 20% and 55% for decreasing heat fluxes, while the thermal resistance increased between 187% and 206% for increasing and between 155% and 175% for decreasing steps in heat pipe with 10 wt.% of Al2O3 NF.

  • 145.
    Motahar, Sadegh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Department of Mechanical Engineering, Isfahan University of Technology, Iran.
    Nikkam, Nader
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Alemrajabi, Ali A.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    A novel phase change material containing mesoporous silica nanoparticles for thermal storage: A study on thermal conductivity and viscosity2014In: International Communications in Heat and Mass Transfer, ISSN 0735-1933, E-ISSN 1879-0178, Vol. 56, p. 114-120Article in journal (Refereed)
    Abstract [en]

    In this research, mesoporous silica (MPSiO2) nanoparticles were dispersed in n-octadecane as an organic phase change material (PCM) in order to produce a novel composite for thermal storage. Stable PCMs containing 1 wt.%, 3 wt.% and 5 wt.% MPSiO2 nanopartides (PCM/MPSiO2) were fabricated by dispersing MPSiO2 in PCM. MPSiO2 particles were investigated by SEM and TEM techniques, which showed high order of porosity and spherical particles of ca. 300 nm. The thermal conductivity in both solid and liquid phases was measured by transient plane source (TPS) technique in the temperature range of 5-55 degrees C. A maximum thermal conductivity enhancement of 5% for 3 wt.% MPSiO2 at 5 degrees C, and 6% for 5 wt.% MPSiO2 at 55 degrees C was experimentally obtained. Moreover, it was observed that enhancement in thermal conductivity is non-monotonic in solid phase with increasing MPSiO2 particle loading. The viscosity results showed that for mass fractions of nanoparticles greater than 3% in liquid PCM, the behavior of liquid is non-Newtonian. Also, the viscosity of PCM containing MPSiO2 nanopartides was measured to be increased up to 60% compared to the liquid PCM for 5 wt% MPSiO2 at 35 degrees C.

  • 146. Motahar, Sadegh
    et al.
    Nikkam, Nader
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Alemrajabi, Ali A.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Experimental investigation on thermal and rheological properties of n-octadecane with dispersed TiO2 nanoparticles2014In: International Communications in Heat and Mass Transfer, ISSN 0735-1933, E-ISSN 1879-0178, Vol. 59, p. 68-74Article in journal (Refereed)
    Abstract [en]

    In the present study, titanium (IV) oxide (TiO2) nanoparticles were dispersed in n-octadecane to fabricate phase change material (PCM) with enhanced properties and behavior. Thermal conductivity (TC) and viscosity of n-octadecane/TiO2 dispersions were experimentally investigated using transient plane source (TPS) technique and rotating coaxial cylindrical viscometer, respectively. The results showed that the TC of n-octadecane/TiO2 dispersion depends on temperature and nanoparticle loading. A non-monotonic behavior of TC enhancement in both solid and liquid phases was observed. In solid phase, the maximum TC enhancement occurred at 3 wt.% of nanoparticles. When the nanoparticle mass fraction was over 4% in liquid phase, the TC started to decrease. The rheological behavior of the n-octadecane/TiO2 samples indicated that dispersions with low nanoparticle mass fractions demonstrate Newtonian behavior, and for higher mass factions the shear-thinning behavior was observed. Shear stress vs. shear rate curves showed that the liquid phase of PCM behaves like a Bingham plastic fluid for mass fraction greater than 1%. As expected, the effective viscosity could be influenced by temperature. At the shear rate of 48.92 s(-1) for 3 wt.% nanoparticles, the effective viscosity decreased by 26.8% while temperature increased from 35 degrees C to 55 degrees C. For the investigated n-octadecane/TiO2 dispersions, new thermophysical correlations are proposed for predicting TC and rheological properties.

  • 147.
    Muhammed, Mamoun
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Nikkam, Nader
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    The use of a suspension comprising mesoporous silica particles as heat exchange fluids: Användningen av en suspension omfattande mesoporösa kiseldioxidartiklar som värmeväxlarvätska2010Patent (Other (popular science, discussion, etc.))
  • 148. Muhammed, Mamoun
    et al.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Nanostructured Skutterudites2006In: Thermoelectrics Handbook: Macro to Nano-Structured Materials / [ed] D.M. Rowe, Taylor & Francis Group, 2006, p. 41-1-41-10Chapter in book (Refereed)
  • 149. Mukherjee, S. P.
    et al.
    Gliga, A. R.
    Lazzaretto, B.
    Brandner, B.
    Fielden, Matthew
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Newman, L.
    Rodrigues, A. F.
    Shao, W.
    Fournier, P. M.
    Toprak, Muhammet Sadaka
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Star, A.
    Kostarelos, K.
    Bhattacharya, K.
    Fadeel, B.
    Graphene oxide is degraded by neutrophils and the degradation products are non-genotoxic2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 3, p. 1180-1188Article in journal (Refereed)
    Abstract [en]

    Neutrophils were previously shown to digest oxidized carbon nanotubes through a myeloperoxidase (MPO)-dependent mechanism, and graphene oxide (GO) was found to undergo degradation when incubated with purified MPO, but there are no studies to date showing degradation of GO by neutrophils. Here we produced endotoxin-free GO by a modified Hummers' method and asked whether primary human neutrophils stimulated to produce neutrophil extracellular traps or activated to undergo degranulation are capable of digesting GO. Biodegradation was assessed using a range of techniques including Raman spectroscopy, transmission electron microscopy, atomic force microscopy, and mass spectrometry. GO sheets of differing lateral dimensions were effectively degraded by neutrophils. As the degradation products could have toxicological implications, we also evaluated the impact of degraded GO on the bronchial epithelial cell line BEAS-2B. MPO-degraded GO was found to be non-cytotoxic and did not elicit any DNA damage. Taken together, these studies have shown that neutrophils can digest GO and that the biodegraded GO is non-toxic for human lung cells.

  • 150.
    Najmoddin, Najmeh
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Beitollahi, Ali
    Devlin, Eamonn
    Kavas, Huseyin
    Mohseni, Seyed Majid
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Åkerman, Johan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Niarchos, Dimitris
    Rezaie, Hamidreza
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Magnetic properties of crystalline mesoporous Zn-substituted copper ferrite synthesized under nanoconfinement in silica matrix2014In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 190, p. 346-355Article in journal (Refereed)
    Abstract [en]

    A series of ordered mesoporous single phase Cu1-xZnxFe2O4 spinel ferrites, with x ranging from 0.00 to 0.75 with a step increment of 0.25, are prepared by a novel nanocasting route with the aid of vinyl-functionalized mesoporous silica as a hard template. All samples display a relatively high surface area and narrow pore size distribution from nitrogen sorption analysis. The magnetic hysteresis loops of these samples measured at 300 K, the temperature dependence of the zero field cooled (ZFC) and field cooled (FC) magnetization curves and the Mossbauer Spectra show the presence of superparamagnetic nanopartides in all samples. The hysteresis data indicate that the maximum saturation magnetization of 52 emu g(-1), is obtained for the composition with x = 0.25. For x >= 0.5, the saturation magnetization decreases as a result of the cation redistribution within tetrahedral (A) and octahedral (B) sites which weakens the A-B interactions due to triangular Yafet-Kittel spin arrangement on the B-sublattice. The observed magnetic features are attributed to the confined spaces of the host material which acts as a nanoreactor, limiting the growth of the embedded oxide phase and significantly influencing the cation distribution of copper-zinc ferrite on the A and B sites.

123456 101 - 150 of 259
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf