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  • 1.
    Abdel-Karim, R.
    et al.
    Department of Metallurgy, Faculty of Engineering, Cairo University.
    Reda, Y.
    Department of Metallurgy, Faculty of Engineering, Cairo University.
    Muhammed, Mamoun A.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    El-Raghy, S.
    Department of Metallurgy, Faculty of Engineering, Cairo University.
    Shoeib, M.
    Metals Technology Department Central Metallurgical Research and Development Institute.
    Ahmed, H.
    Department of Metallurgy, Faculty of Engineering, Cairo University.
    Electrodeposition and Characterization of Nanocrystalline Ni-Fe Alloys2011In: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, p. 519274-Article in journal (Refereed)
    Abstract [en]

    Nanocrystalline Ni-Fe deposits with different composition and grain sizes were fabricated by electrodeposition. Deposits with iron contents in the range from 7 to 31% were obtained by changing the Ni(2+)/Fe(2+) mass ratio in the electrolyte. The deposits were found to be nanocrystalline with average grain size in the range 20-30 nm. The surface morphology was found to be dependent on Ni(2+)/Fe(2+) mass ratio as well as electroplating time. The grains size decreased with increasing the iron content, especially in case of short time electroplating. Increasing the electroplating time had no significant effect on grain size. The microhardness of the materials followed the regular Hall-Petch relationship with amaximum value (762 Hv) when applying Ni(2+)/Fe(2+) mass ratio equal to 9.8.

  • 2. Abderrazek, K.
    et al.
    Uheida, Abdusalam
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Seffen, M.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Srasra, N. Frini
    Srasra, E.
    Photocatalytic degradation of indigo carmine using [Zn-Al] LDH supported on PAN nanofibres2015In: Clay minerals, ISSN 0009-8558, E-ISSN 1471-8030, Vol. 50, no 2, p. 185-197Article in journal (Refereed)
    Abstract [en]

    Zn-Al layered double hydroxides (LDH), before and after calcination, were tested for the removal of indigo carmine (IC) dye from solution. These LDH photocatalysts were characterized by powder x-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetry/differential thermogravimetry (TG/DTG), nitrogen physisorption at -196 degrees C, scanning electron microscopy (SEM) and diffuse reflectance spectrophotometry (DRS). The different photocatalysts were supported on polyacrylonitrile (PAN) nanofibres, so that filtration was unnecessary. The PXRD and FTIR analyses showed that the IC adsorption on c-Zn-Al-3-500 (LDH calcined at 500 degrees C) was enhanced by construction of the hydrotalcite matrix intercalated with the dye. The intercalation was clearly evidenced by the appearance of a peak at low degrees 2 theta values. All of the materials prepared exhibited photocatalytic activity, which for the c-Zn-Al-3-500 was comparable to that of commercial PAN-supported ZnO nanoparticles (100% degradation after 180 min). Kinetic studies showed that the degradation of the IC followed a pseudo-first order rate. The high activity and the ease of both synthesis and separation processes rendered this photocatalyst a promising candidate for environmental remediation.

  • 3.
    Adamopoulos, Othon
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Functional Materials, FNM (Closed 20120101).
    Björkman, Eva
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Functional Materials, FNM (Closed 20120101).
    Zhang, Yu
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Functional Materials, FNM (Closed 20120101).
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Functional Materials, FNM (Closed 20120101).
    Bog, Tassilo
    Mussmann, Lothar
    Lox, Egbert
    A nanophase oxygen storage material: Alumina-coated metal-based ceria2009In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 29, no 4, p. 677-689Article in journal (Refereed)
    Abstract [en]

    Nanoparticles of Ce1-xMxO2-delta (M = Ca or Zr) coated with Al2O3 with average crystallite size of 10 nm have been synthesised via solution chemistry approach under controlled chemical and hydrodynamic conditions. Their synthesis has been accomplished in three major steps: (1) simultaneous co-precipitation of cations, (2) sequential precipitation of Al(OH)(3) over the former particles and (3) calcination of the precipitated precursors to the corresponding oxides. Several compositions have been synthesised and their physicochemical properties are compared with commercial state-of-the-art material. The Al2O3-coating hinders the particles growth at high temperatures, resulting in materials with a large specific surface area and a restrain in the decrease of their oxygen storage capacity.

  • 4.
    Afrasiabi, Roodabeh
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Sugunan, Abhilash
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Shahid, Robina
    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.
    Microwave mediated synthesis of semiconductor quantum dots2012In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, no 7, p. 1551-1556Article in journal (Refereed)
    Abstract [en]

    Colloidal quantum dots (QD) have tuneable optoelectronic properties and can be easily handled by simple solution processing techniques, making them very attractive for a wide range of applications. Over the past decade synthesis of morphology controlled high quality (crystalline, monodisperse) colloidal QDs by thermal decomposition of organometallic precursors has matured and is well studied. Recently, synthesis of colloidal QDs by microwave irradiation as heating source is being studied due to the inherently different mechanisms of heat transfer, when compared to solvent convection based heating. Under microwave irradiation, polar precursor molecules directly absorb the microwave energy and heat up more efficiently. Here we report synthesis of colloidal II-VI semiconductor QDs (CdS, CdSe, CdTe) by microwave irradiation and compare it with conventional synthesis based on convection heating. Our findings show that QD synthesis by microwave heating is more efficient and the chalcogenide precursor strongly absorbs the microwave radiation shortening the reaction time and giving a high reaction yield.

  • 5.
    Asem, Heba
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM. Karolinska Inst, Sweden.
    Abd El-Fattah, Ahmed
    Nafee, Noha
    Zhao, Ying
    Khalil, Labiba
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Hassan, Moustapha
    Kandil, Sherif
    Development and biodistribution of a theranostic aluminum phthalocyanine nanophotosensitizer2016In: Photodiagnosis and Photodynamic Therapy, ISSN 1572-1000, E-ISSN 1873-1597, Vol. 13, p. 48-57Article in journal (Refereed)
    Abstract [en]

    Background: Aluminum phthalocyanine (AlPc) is an efficient second generation photosensitizer (PS) with high fluorescence ability. Its use in photodynamic therapy (PDT) is hampered by hydrophobicity and poor biodistribution. Methods: AlPc was converted to a biocompatible nanostructure by incorporation into amphiphilic polyethylene glycol-polycaprolactone (PECL) copolymer nanoparticles, allowing efficient entrapment of the PS in the hydrophobic core, water dispersibility and biodistribution enhancement by PEG-induced surface characteristics. A series of synthesized PECL copolymers were used to prepare nanophotosensitizers with an average diameter of 66.5-99.1 nm and encapsulation efficiency (EE%) of 66.4-78.0%. One formulation with favorable colloidal properties and relatively slow release over 7 days was selected for in vitro photophysical assessment and in vivo biodistribution studies in mice. Results: The photophysical properties of AlPc were improved by encapsulating AlPc into PECL-NPs, which showed intense fluorescence emission at 687 nm and no AlPc aggregation has been induced after entrapment into the nanoparticles. Biodistribution of AlPc loaded NPs (AlPc-NPs) and free AlPc drug in mice was monitored by in vivo whole body fluorescence imaging and ex vivo organ imaging, with in vivo imaging system (IVIS). Compared to a AlPc solution in aqueous TWEEN 80 (2 w/v%), the developed nanophotosensitizer showed targeted drug delivery to lungs, liver and spleen as monitored by the intrinsic fluorescence of AlPc at different time points (1 h, 24 h and 48 h) post iv. administration. Conclusions: The AlPc-based copolymer nanoparticles developed offer potential as a single agent multifunctional theranostic nanophotosensitizer for PDT coupled with imaging-guided drug delivery and biodistribution, and possibly also fluorescence diagnostics.

  • 6.
    Asem, Heba
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM. Karolinska Institutet (KI), Sweden.
    Zhao, Ying
    Ye, Fei
    Barrefelt, Asa
    Abedi-Valugerdi, Manuchehr
    El-Sayed, Ramy
    El-Serafi, Ibrahim
    Abu-Salah, Khalid M.
    Hamm, Jorg
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Hassan, Moustapha
    Biodistribution of biodegradable polymeric nano-carriers loaded with busulphan and designed for multimodal imaging2016In: Journal of Nanobiotechnology, ISSN 1477-3155, Vol. 14, no 1, article id 82Article in journal (Refereed)
    Abstract [en]

    Background: Multifunctional nanocarriers for controlled drug delivery, imaging of disease development and follow-up of treatment efficacy are promising novel tools for disease diagnosis and treatment. In the current investigation, we present a multifunctional theranostic nanocarrier system for anticancer drug delivery and molecular imaging. Superparamagnetic iron oxide nanoparticles (SPIONs) as an MRI contrast agent and busulphan as a model for lipophilic antineoplastic drugs were encapsulated into poly (ethylene glycol)-co-poly (caprolactone) (PEG-PCL) micelles via the emulsion-evaporation method, and PEG-PCL was labelled with VivoTag 680XL fluorochrome for in vivo fluorescence imaging. Results: Busulphan entrapment efficiency was 83% while the drug release showed a sustained pattern over 10 h. SPION loaded-PEG-PCL micelles showed contrast enhancement in T-2*-weighted MRI with high r(2)* relaxivity. In vitro cellular uptake of PEG-PCL micelles labeled with fluorescein in J774A cells was found to be time-dependent. The maximum uptake was observed after 24 h of incubation. The biodistribution of PEG-PCL micelles functionalized with VivoTag 680XL was investigated in Balb/c mice over 48 h using in vivo fluorescence imaging. The results of real-time live imaging were then confirmed by ex vivo organ imaging and histological examination. Generally, PEG-PCL micelles were highly distributed into the lungs during the first 4 h post intravenous administration, then redistributed and accumulated in liver and spleen until 48 h post administration. No pathological impairment was found in the major organs studied. Conclusions: Thus, with loaded contrast agent and conjugated fluorochrome, PEG-PCL micelles as biodegradable and biocompatible nanocarriers are efficient multimodal imaging agents, offering high drug loading capacity, and sustained drug release. These might offer high treatment efficacy and real-time tracking of the drug delivery system in vivo, which is crucial for designing of an efficient drug delivery system.

  • 7.
    Ashour, Radwa M.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Functional Materials, FNM. Nuclear Materials Authority, Egypt.
    El-sayed, R.
    Abdel-Magied, A. F.
    Abdel-khalek, A. A.
    Ali, M. M.
    Forsberg, Kerstin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Uheida, Abdusalam
    KTH, School of Engineering Sciences (SCI), Applied Physics, Functional Materials, FNM.
    Muhammed, Mamoun
    KTH, School of Engineering Sciences (SCI), Applied Physics, Functional Materials, FNM.
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics, Functional Materials, FNM.
    Selective separation of rare earth ions from aqueous solution using functionalized magnetite nanoparticles: kinetic and thermodynamic studies2017In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 327, p. 286-296Article in journal (Refereed)
    Abstract [en]

    Separation of rare earth ions (RE3+) from aqueous solution is a tricky problem due to their physico-chemical similarities of properties. In this study, we investigate the influence of the functionalized ligands on the adsorption efficiency and selective adsorption of La3+, Nd3+, Gd3+ and Y3+ from aqueous solution using Magnetite (Fe3O4) nanoparticles (NPs) functionalized with citric acid (CA@Fe3O4 NPs) or L-cysteine (Cys@Fe3O4 NPs). The microstructure, thermal behavior and surface functionalization of the synthesized nanoparticles were studied. The general adsorption capacity of Cys@Fe3O4 NPs was found to be high (98 mg g−1) in comparison to CA@Fe3O4 NPs (52 mg g−1) at neutral pH 7.0. The adsorption kinetic studies revealed that the adsorption of RE3+ ions follows a pseudo second-order model and the adsorption equilibrium data fits well to the Langmuir isotherm. Thermodynamic studies imply that the adsorption process was endothermic and spontaneous in nature. Controlled desorption within 30 min of the adsorbed RE3+ ions from both Cys@Fe3O4 NPs and CA@Fe3O4 NPs was achieved with 0.5 M HNO3. Furthermore, Cys@Fe3O4 NPs exhibited a higher separation factor (SF) in the separation of Gd3+/La3+, Gd3+/Nd3+, Gd3+/Y3+ ions compared to CA@Fe3O4 NPs.

  • 8.
    Avila, Marta
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Burks, Terrance
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Akhtar, F.
    Department of Materials and Environmental Chemistry, Stockholm Universtiy, Stockholm, Sweden.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Lansåker, P. C.
    Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    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.
    Uheida, Abdusalam
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Surface functionalized nanofibers for the removal of chromium(VI) from aqueous solutions2014In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 245, p. 201-209Article in journal (Refereed)
    Abstract [en]

    Polyacrylonitrile (PAN) nanofibers functionalized with amine groups (PAN-NH2) were prepared using a simple one-step reaction route. The PAN-NH2 nanofibers were investigated for the removal of chromium(VI) from aqueous solutions. The adsorption and the kinetic characteristics were evaluated in batch process. The adsorption process showed pH dependence and the maximum Cr(VI) adsorption occurred at pH = 2. The Langmuir adsorption model described well the experimental adsorption data and estimated a maximum loading capacity of 156 mg/g, which is a markedly high value compared to other adsorbents reported. The kinetics studies indicated that the equilibrium was attained after 90 min and the experimental data followed a pseudo-second order model suggesting a chemisorption process as the rate limiting step. X-ray Photoelectron Spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) revealed that the adsorption of Cr(VI) species on PAN-NH2 was facilitated through both electrostatic attraction and surface complexation. High desorption efficiency (> 90%) of Cr(VI) was achieved using diluted base solutions that may allow the reuse of PAN-NH2 nanofibers.

  • 9. Barrefelt, Åsa
    et al.
    Paradossi, Gaio
    Asem, Heba
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Margheritelli, Silvia
    Saghafian, Maryam
    Oddo, Letizia
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Aspelin, Peter
    Hassan, Moustapha
    Brismar, Torkel B.
    DYNAMIC MR IMAGING, BIODISTRIBUTION AND PHARMACOKINETICS OF POLYMER SHELLED MICROBUBBLES CONTAINING SPION2014In: NANO, ISSN 1793-2920, Vol. 9, no 6, p. 1450069-Article in journal (Refereed)
    Abstract [en]

    Magnetic Resonance Imaging (MRI) is a noninvasive diagnostic method that provides information on morphological and physiological changes of the internal organs over time. Imaging and measurements can be repeated on the same subject, thereby reducing inter-individual variability effects and hence the number of subjects required. A potential MRI contrast agent consisting of microbubbles embedded with superparamagnetic iron oxide nanoparticles (SPION) in the shell (SPION MBs) was injected intravenously into rats to determine their biodistribution and pharmacokinetics using MR imaging. Agarose phantoms containing SPION MBs were scanned using 3 T MRI to construct a standard curve. Rats were injected with SPION MBs, free SPION or plain MBs and scanned dynamically at 3 T using a clinical MR scanner. The relaxation rate (R2*) was studied over time as a measure of the iron oxide concentrations to enable calculation of the pharmacokinetic parameters. The kinetics of SPION MBs in the liver was fitted to a one-compartment model. Furthermore, the biological fate of SPION MBs was examined via a histological survey of tissue samples using Perls' Prussian blue staining and immunohistochemistry (IHC). 1.2 h after injection of SPION MBs, T2* of the liver had decreased to its minimum. The elimination half-life of SPION MBs was 598.2 +/- 97.3 h, while the half-life for SPION was 222.6 +/- 26.4 h. Moreover, our study showed that SPION MBs were taken up by the macrophages in the lungs, spleen and liver. MBs labeled with SPION can be used for MR imaging. Moreover, MRI is a reliable and noninvasive tool that can be utilized in pharmacokinetic investigations of future contrast agents using SPION MBs and SPION in the rat.

  • 10. Barrefelt, Åsa
    et al.
    Saghafian, Maryam
    Kuiper, Raoul
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Egri, Gabriella
    Klickermann, Moritz
    Brismar, Torkel B.
    Aspelin, Peter
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Daehne, Lars
    Hassan, Moustapha
    Biodistribution, kinetics, and biological fate of SPION microbubbles in the rat2013In: International Journal of Nanomedicine, ISSN 1176-9114, E-ISSN 1178-2013, Vol. 8, p. 3241-3254Article in journal (Refereed)
    Abstract [en]

    Background: In the present investigation, we studied the kinetics and biodistribution of a contrast agent consisting of poly(vinyl alcohol) (PVA) microbubbles containing superparamagnetic iron oxide (SPION) trapped between the PVA layers (SPION microbubbles). Methods: The biological fate of SPION microbubbles was determined in Sprague-Dawley rats after intravenous administration. Biodistribution and elimination of the microbubbles were studied in rats using magnetic resonance imaging for a period of 6 weeks. The rats were sacrificed and perfusion-fixated at different time points. The magnetic resonance imaging results obtained were compared with histopathologic findings in different organs. Results: SPION microbubbles could be detected in the liver using magnetic resonance imaging as early as 10 minutes post injection. The maximum signal was detected between 24 hours and one week post injection. Histopathology showed the presence of clustered SPION microbubbles predominantly in the lungs from the first time point investigated (10 minutes). The frequency of microbubbles declined in the pulmonary vasculature and increased in pulmonary, hepatic, and splenic macrophages over time, resulting in a relative shift from the lungs to the spleen and liver. Meanwhile, macrophages showed increasing signs of cytoplasmic iron accumulation, initially in the lungs, then followed by other organs. Conclusion: The present investigation highlights the biological behavior of SPION microbubbles, including organ distribution over time and indications for biodegradation. The present results are essential for developing SPION microbubbles as a potential contrast agent and/or a drug delivery vehicle for specific organs. Such a vehicle will facilitate the use of multimodality imaging techniques, including ultrasound, magnetic resonance imaging, and single positron emission computed tomography, and hence improve diagnostics, therapy, and the ability to monitor the efficacy of treatment.

  • 11. Baudin, M.
    et al.
    Wojcik, M.
    Hermansson, Kersti
    KTH, Superseded Departments, Biotechnology.
    Palmqvist, A. E. C.
    Muhammed, Mamoun
    KTH, Superseded Departments, Materials Science and Engineering.
    MD simulations of a doped ceria surface - very large surface ion motion2001In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 335, no 06-maj, p. 517-523Article in journal (Refereed)
    Abstract [en]

    Mean-square displacements (MSDs) and individual-ion square-displacements (ISDs) for the different constituents in Ca-doped CeO2(0 1 1) slabs at 300 K have been studied as a function of depth from the surface. Constant pressure-constant temperature MD simulations were used. The MSDs are 2-3 times larger at the surface than in the bulk, but ISDs as large as ca. 150 times the surface MSD value were observed during short-time periods for anions next to an anion vacancy at the surface. The chemical implications of this kind of motion are important, since transient structural distortions of this magnitude will lead to large electron re-distributions.

  • 12. Bertini, L
    et al.
    Stiewe, C
    Toprak, Muhammet S.
    KTH, Superseded Departments, Materials Science and Engineering.
    Williams, S
    Platzek, D
    Mrotzek, A
    Zhang, Y
    Gatti, C
    Muller, E
    Muhammed, Mamoun
    KTH, Superseded Departments, Materials Science and Engineering.
    Rowe, M
    Nanostructured Co1-xNixSb3 skutterudites: Synthesis, thermoelectric properties, and theoretical modeling2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 93, no 1, p. 438-447Article in journal (Refereed)
    Abstract [en]

    Nanostructured skutterudite Co1-xNixSb3 has been synthesized by chemical alloying with Ni substitution for Co up to 27.5 at. %. High concentration of grain boundaries provided by nanostructuring is expected to lower the thermal conductivity of thermoelectric materials and could thus increase their thermoelectric dimensionless figure-of-merit ZT. Material preparation comprises two key stages, coprecipitation of the precursor, and thermal processing to produce the skutterudite. By modeling the chemistry of the metal ions in aqueous solution, optimum coprecipitation conditions were achieved. The precipitated precursor consists of a solid solution of the different intermediate compounds, and exhibits high reactivity. Calcination and reduction of the precursor resulted in the alloying of these elements and in the formation of skutterudite at a temperature as low as 723-773 K. Unfilled CoSb3 skutterudites were prepared by chemical precipitation from aqueous solutions to achieve powders with a very small grain size (similar to40 nm). Compacted samples were produced from this powder by uniaxial pressing under various conditions. Thermal conductivity, electrical resistivity and Seebeck coefficient of the resulting compacts were measured in a temperature range from 150 to 575 K. Measurement procedures were standardized for absolute accuracy and reproducibility between the DLR, Cologne and NEDO, Cardiff Laboratories. It was found that the thermal conductivity can be decreased by almost an order of magnitude at the highest concentration of grain boundaries compared to highly annealed CoSb3. Scanning Seebeck microthermoprobe examination, facilitated spatially resolved measurement of Seebeck coefficient S, providing information on samples' homogeneity and on its effect on local S. Indications on the formation of an additional Ni containing phase were found. The electronic structure of Ni-doped skutterudites has been investigated by means of fully periodic density functional theory calculations and a topological analysis of the resulting electron densities. Ni substitution for Co doubles the electronic charge transfer from the pnicogen ring to the metal frame and fills the region of the CoSb3 band gap with occupied states, thus explaining the increase of electrical conductivity observed experimentally. The effect of the Ni substitution on the thermal conductivity is analyzed. The computed changes of the cell parameter with rising Ni content differ with those found by x-ray powder diffraction, thereby suggesting that the structural hypothesis of Ni replacing Co in the cubic frame of the skutterudite is only approximate or possibly incorrect.

  • 13. Biesuz, R.
    et al.
    Zagorodni, A. A.
    Muhammed, Mamoun
    KTH, Superseded Departments, Materials Science and Engineering.
    Estimation of deprotonation coefficients for chelating ion exchange resins. Comparison of different thermodynamic model2001In: Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 105, no 20, p. 4721-4726Article in journal (Refereed)
    Abstract [en]

    The deprotonation of quinolic resin P-127 and iminodiacetic resin Amberlite IRC-718 has been studied. The process of salt transfer into the resin phase is considered to be an important contributor to the deprotonation process. Estimation of the salt transfer was based on the principle of equal activity of the salt in both phases at equilibrium. Two assumptions were made: sorbed alkali metal ions are not associated with functional groups, while all hydrogen ions are associated with functional groups. The associated hydrogen ions and functional groups do not contribute to the internal ionic strength value. Two thermodynamic models, describing the deprotonation of ion-exchange resin, were used and compared: the Gibbs-Donnan-based model of Bukata and Marinsky and the model proposed by Erik Hogfeldt. Thermodynamic characteristics of the resins' deprotonation are obtained using two different thermodynamic approaches. Hogfeldt's three-parameter model provides a better agreement with experimental data. The fitting of the data to Marinsky's method can be improved by taking into account the influence of the resins' macroporosity; however, this requires an additional empirical parameter to describe the resin.

  • 14.
    Bitaraf Haghighi, Ehsan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Nikkam, Nader
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Saleemi, Mohsin
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Behi, Mohammadreza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Mirmohammadi, Seyed Aliakbar
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Poth, H.
    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, Functional Materials, FNM.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Shelf stability of nanofluids and its effect on thermal conductivity and viscosity2013In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 24, no 10, p. 105301-Article in journal (Refereed)
    Abstract [en]

    This study proposes a method and apparatus to estimate shelf stability of nanofluids. Nanofluids are fabricated by dispersion of solid nanoparticles in base fluids, and shelf stability is a key issue for many practical applications of these fluids. In this study, shelf stability is evaluated by measuring the weight of settled solid particles on a suspended tray in a colloid versus time and correlated with the performance change of some nanofluid systems. The effects of solid particle concentration and bath sonication time were investigated for selected nanofluids. The results show the applicability of this simple method and the apparatus to evaluate nanofluid shelf stability. Furthermore, it shows that Stokes' law is not valid for determining the settling time of the tested nanoparticles probably due to their complicated shape and presence of surface modifiers. The effect of shelf stability on thermal conductivity and viscosity was illustrated for some nanofluids. Experimental results show that water-based Al2O3 nanofluids have quite good shelf stability and can be good candidates for industrial applications.

  • 15.
    Bitaraf Haghighi, Ehsan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Saleemi, Mohsin
    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.
    Anwar, Zahid
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lumbreras, Itziar
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Behi, Mohammadreza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Mirmohammadi, Seyed A.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Poth, Heiko
    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, Functional Materials, FNM.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Cooling performance of nanofluids in a small diameter tube2013In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 49, p. 114-122Article in journal (Refereed)
    Abstract [en]

    This article reports convective single-phase heat transfer performance in laminar flow for some selected nanofluids (NFs) in an open small diameter test section. A 0.50 mm inner diameter, 30 cm long stainless steel test section was used for screening single phase laminar convective heat transfer with water and five different water based NFs. Tested NFs were; Al2O3 (two types), TiO2 (two types) and CeO2 (one type), all 9 wt.% particle concentration. The effective thermal conductivity of the NFs were measured with Transient Plane Source (TPS) method and viscosity were measured with a rotating coaxial cylindrical viscometer. The obtained experimental results for thermal conductivity were in good agreement with the predicted values from Maxwell equation. The local Shah correlation, which is conventionally used for predicting convective heat transfer in laminar flow in Newtonian fluids with constant heat flux boundary condition, was shown to be valid for NFs. Moreover, the Darcy correlation was used to predict the friction factor for the NFs as well as for water. Enhancement in heat transfer for NFs was observed, when compared at equal Reynolds number, as a result of higher velocity or mass flow rate of the NFs at any given Reynolds number due to higher viscosity for NFs. However, when compared at equal pumping power no or only minor enhancement was observed.

  • 16.
    Bitaraf Haghighi, Ehsan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Saleemi, Mohsin
    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.
    Ghadamgahi, Mersedeh
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Khodabandeh, Rahmatollah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Toprak, Muhammet
    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.
    Measurement of temperature–dependent viscosity of nanofluids and its effect on pumping power in cooling systems2013Conference paper (Refereed)
    Abstract [en]

    Nanofluids are engineered colloids of nanoparticlesdispersed homogenously in a base fluid, which theirthermophysical properties are changed by adding solidnanoparticles. Among the characteristic parameters,viscosity is one of the most important, as it directly affectsthe pumping power in cooling systems. In this study, theviscosity of water based Al2O3, ZrO2, and TiO2 (with 9wt%for all) nanofluids was measured and its impact on pressuredrop in a simple tubular pipe was estimated for bothlaminar and turbulent flow by classical correlations. Theeffect of temperature on the viscosity of these nanofluidswas also studied in the temperature range of 5˚C - 30˚C. Toassess the applicability of the classical correlations, pressuredrops across an open 30cm long, 0.50mm diameterstainless steel test section was measured for water andnanofluids by a differential pressure transducer. Theaverage viscosity increments compared to water in thetemperature range of 5˚C - 30˚C are 105%, 98% and 31% forAl2O3, ZrO2, and TiO2 nanofluids respectively. Moreover, theresults show that the viscosity of nanofluids decreases withthe increase of temperature; however the relative viscosity,which is defined as the viscosity ratio between a nanofluidand its base fluid is constant in 5˚C - 30˚C temperaturerange.

  • 17. BOG, T
    et al.
    MUSSMANN, L
    LINDNER, D
    VOTSMEIER, M
    FEGER, M
    LOX, E
    KREUZER, T
    Muhammed, Mamoud
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    ADAMOPOULOS, O
    Oxygen storage material production useful in exhaust gas cleaning catalyst, involves mixing aqueous solution of cerium oxide precursor with aqueous solution of precursor of oxide of metal, and adding first precipitation agent to mixture.2003Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    NOVELTY - Oxygen storage material production comprises mixing aqueous solution of cerium oxide precursor with aqueous solution of precursor of oxide of metal to form mixture, adding first precipitation agent to mixture to form aqueous suspension containing precipitate, separating precipitate from suspension, drying and calcining precipitate. The oxygen storage material comprises cerium oxide and second oxide of a metal. The metal is alkaline earth metal, rare earth metal, zirconium, zinc, cobalt, copper and/or manganese. USE - The method is useful for producing oxygen storage material useful in exhaust gas cleaning catalyst for purifying exhaust gases of internal combustion engines especially of stoichiometrically operated otto engines. ADVANTAGE - The method provides catalyst that shows excellent activity for purifying harmful pollutant like carbon monoxide, nitrogen oxides, and hydrocarbons. The oxygen storage materials are able to store oxygen in oxidizing atmosphere or release oxygen under reducing conditions, respectively. The oxygen storage material has high specific surface area after thermal aging and improved oxygen storage and release capacity under dynamic exhaust conditions. The storage material shows unprecedented high oxygen storage capacity and excellent dynamic properties with respect to oxygen storage and release compared to conventional materials. DESCRIPTION OF DRAWING(S) - The figure shows setup of precipitation reactor. Precipitation reactor (1) Hydrolysis reactor (2) Tubular flow reactor (3) Precipitation solution (4) Feed (5) Mixer (7) Ph meter (8)

  • 18.
    Burks, Terrance
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Avila, Marta
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Akhtar, F.
    Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden.
    Götelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Lansåker, P. C.
    Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    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.
    Uheida, Abdusalam
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Studies on the adsorption of chromium(VI) onto 3-Mercaptopropionic acid coated superparamagnetic iron oxide nanoparticles2014In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 425, p. 36-43Article in journal (Refereed)
    Abstract [en]

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

  • 19.
    Burks, Terrance
    et al.
    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.
    Saleemi, Mohsin
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Eita, Mohamed
    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.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Removal of Chromium(VI) Using Surface Modified Superparamagnetic Iron Oxide Nanoparticles2013In: Separation science and technology (Print), ISSN 0149-6395, E-ISSN 1520-5754, Vol. 48, no 8, p. 1243-1251Article in journal (Refereed)
    Abstract [en]

    This study describes the removal of Chromium(VI) from aqueous solutions using surface tailored superparamagnetic iron oxide nanoparticles (SPION) coated with bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex-301). The synthesized Cyanex-301 coated SPION has been characterized by Transmission Electron Microscopy (TEM), Fourier-Transfer Infrared Spectroscopy (FT-IR), X-ray Photonic Spectroscopy (XPS), and Thermogravimetric Analysis (TGA). The adsorption mechanism was proposed to be via complexation between the thiol group on Cyanex-301 and Cr(VI) ions based on the XPS and FTIR analysis. It has been found that the equilibrium can be attained in less than 2hr. The adsorption behavior of Cr(VI) on the Cyanex-301 coated SPION can be well described by the Langmuir model and the maximum adsorption capacity for Cr(VI) was estimated to be 30.8mg/g. The selectivity of the Cyanex-301 coated SPION adsorbent towards Cr(VI) ions was found to be high and the maximum loading capacity obtained is up to an order of magnitude higher than that of other adsorbents reported in the literature. The desorption studies showed that more than 70% of Cr(VI) can be recovered using HNO3 as eluting solution. Our findings suggest a high potential of the designed adsorbent material for the treatment of industrial wastewater containing Cr(VI).

  • 20. Christensen, M
    et al.
    Iversen, BB
    Bertini, L
    Gatti, C
    Toprak, Muhammet S.
    KTH, Superseded Departments, Materials Science and Engineering.
    Muhammed, Mamoun
    KTH, Superseded Departments, Materials Science and Engineering.
    Nishibori, E
    Structural study of Fe doped and Ni substituted thermoelectric skutterudites by combined synchrotron and neutron powder diffraction and ab initio theory2004In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 96, no 6, p. 3148-3157Article in journal (Refereed)
    Abstract [en]

    We present neutron and synchrotron powder-diffraction investigations as well as ab initio calculations to elucidate delicate structural features in doped skutterudites. Samples with assumed Fe doping were investigated (FeyCo4Sb12, y=0.4, 0.8, 1.0, and 1.6), as well as samples with formal Ni substitution (Co4-xNixSb12, x=0, 0.4, 0.8, and 1.2). The present study serves as a case story for the determination of fine structural details of thermoelectric skutterudites by diffraction methods in combination with ab initio calculations. We illustrate the problem of fluorescence in the conventional x-ray powder diffraction on the Fe-doped samples by a comparison with the neutron powder-diffraction data. On the series of the Ni-substituted samples, the neutron powder-diffraction data were collected to investigate the exact sitting of the Ni. The sample with the highest Ni substitution (Co2.8Ni1.2Sb12) was also used for high resolution, high-energy synchrotron powder diffraction measurements. These revealed that the sample consists of two skutterudite phases. A complete description of the Ni-substituted samples was obtained in tandem with ab initio calculations, which show that the system contains a Ni-rich (Co0.38Ni3.62Sb12) and a Ni-poor (Co3.76Ni0.24Sb12)) skutterudite phases.

  • 21.
    Dai, Jin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101).
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Functional Materials, FNM (Closed 20120101).
    Chen, Yiting
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101).
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Functional Materials, FNM (Closed 20120101).
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101).
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101).
    Light absorber based on nano-spheres on a substrate reflector2013In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, no 6, p. 6697-6706Article in journal (Refereed)
    Abstract [en]

    We systematically study a type of plasmonic light absorber based on a monolayer of gold nano-spheres with less than 30 nm in diameters deposited on top of a continuous gold substrate. The influences of particle size, inter-particle distance, particle-substrate spacer size etc on the resonance are studied thoroughly with a 3D finite-element method. We identified that the high-absorption resonance is mainly due to gap plasmon (coupled through particle bodies) when the separation between neighboring nano-spheres is small enough, such as close to 1 nm; at larger particle separations, the resonance is dominated by particle dipoles (coupled through the host dielectric). Experimentally, an absorber was fabricated based on chemically-synthesized gold nanoparticles coated with silica shell. The absorber shows a characteristic absorption band around 810 nm with a maximum absorbance of approximately 90%, which agrees reasonably well with our numerical calculation. The fabrication technique can be easily adapted for devising efficient light absorbers of large areas.

  • 22.
    Darab, Mahdi
    et al.
    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.
    Syvertsen, Guttorm Ernst
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Nanoengineered BSCF Cathode Materials for Intermediate-Temperature Solid-Oxide Fuel Cells2009In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 156, no 8, p. K139-K143Article in journal (Refereed)
    Abstract [en]

    A recently reported promising cathode material for solid-oxide fuel cells (SOFCs), namely, BaxSr1-xCoyFe1-yO3-delta (BSCF) is fabricated in nanocrystalline form by a chemical alloying approach. The approach is comprised of solution chemical synthesis of a precursor and its thermochemical processing toward the desired phase. All the constituent elements, Ba, Sr, Co, and Fe, were coprecipitated from an aqueous solution of their salts to produce a precursor with a well-defined composition, fine particle size, high homogeneity, and high reactivity. After calcining and sintering at 1000 degrees C, the individual oxides were alloyed into nanostructured perovskite (with x=0.5 and y=0.2) Ba0.5Sr0.5Co0.2Fe0.8O3 of high purity. Spark plasma sintering was used for compaction to preserve the material's nanostructure, and sintered compacts demonstrated a significant increase in electrical conductivity values at temperatures up to 900 degrees C, compared to the earlier reports. The measured conductivity values are sufficiently high for cathode applications with a maximum of about 63 S cm(-1) at 430 degrees C in air and 25 S cm(-1) at 375 degrees C in N-2, respectively. These values are about twice as high as conventional BSCF mainly due to the reduction in interfacial resistance, implying a high promise for nanoengineered BSCF as cathode material at low or intermediate-temperature SOFCs.

  • 23.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Hu, Jun
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. Zhejiang University, China.
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. Helsinki University of Technology, Finland.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Influence of nanoparticles concentration on fluorescence quenching in gold/rhodamine 6G nanoassemblies2009In: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009, Optical Society of America, 2009, p. 5377045-Conference paper (Refereed)
    Abstract [en]

    Fluorescence enhancement of dye solution doped with gold nanoparticles is a well-known effect. However, depending on size and concentration, nanoparticles can also deteriorate dye lasing properties due to increased quenching of the excited molecules. Here we report experimental results on such dependence of fluorescence degradation on the nanoparticle concentration.

  • 24.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Pinos, Andrea
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Sugunan, Abhilash
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Li, Shanghua
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Popov, Sergei
    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.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. Helsinki University of Technology, Finland.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Measurement of radiative lifetime in CdSe/CdS core/shell structured quantum dots2009In: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009, 2009, p. 5377385-Conference paper (Refereed)
    Abstract [en]

    Radiative lifetime of chemically synthesized colloidal CdSe/CdS core/shell quantum dots is measured. Influence of the core size on the electron-hole pair separation is analyzed. A long radiative lifetime and the existence of electron-hole pair separation suggest high potential of these dots as gain material to achieve lasing under continuous-wave excitation.

  • 25.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Sugunan, Abhilash
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Hu, Jun
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Zhou, Sicheng
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Li, Shanghua
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Photoluminescence from quasi-type-II spherical CdSe-CdS core-shell quantum dots2013In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 52, no 1, p. 105-109Article in journal (Refereed)
    Abstract [en]

    Spherical CdSe-CdS core-shell quantum dots (QDs) are found to be flexible in the transition between the type-I regime and the type-II regime with different core/shell dimensions. The quasi-type-II feature of the colloidal dots is confirmed with time-resolved photoluminescence (PL) measurements. Two recombination paths of the excitons with significantly different decay rates are observed and analyzed. The spherical CdSe-CdS core-shell QDs are numerically simulated to investigate the carrier separation. A relatively long radiative lifetime and high degree of spatial carrier separation provide good potential to achieve lasing under continuous-wave excitation. Amplified spontaneous emission at room temperature is detected from the QDs embedded in the polymer matrix. It is shown that a larger shell thickness results in a lower pumping threshold, while a smaller shell thickness leads to higher PL efficiency.

  • 26.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Chughtai, Adnan
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Liuolia, Vytautas
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Lasing From Water Solution of Rhodamine 6G/Gold Nanoparticles: Impact of SiO2-Coating on Metal Surface2012In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 48, no 9, p. 1220-1226Article in journal (Refereed)
    Abstract [en]

    Gold nanoparticles embedded in an optical gain material, particularly in a water solution of Rhodamine 6G, used in dye lasers can both increase and damp dye flourescence, thus changing the laser output intensity. Simultaneously, such nanoparticles influence the gain material's resistance against photobleaching. In this paper, we report our study on the impact of the SiO2 coating of nanoparticles on the enhancement or quenching and photobleaching of the fluorescence. The investigation demonstrates a noticeable improvement of the gain material's photostability compared to uncoated gold nanoparticles when silicon dioxide coating is implemented.

  • 27.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Chughtai, Adnan
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Enhanced photostability of aqueous solution of Rhodamine 6G with gold nanoparticles in lasing process by silica coating2012In: 2012 Conference on Lasers and Electro-Optics, CLEO 2012, IEEE , 2012, p. 6325399-Conference paper (Refereed)
    Abstract [en]

    Gold nanoparticles are mixed in aqueous solution of Rhodamine 6G to modify the lasing output intensity. The photostability deterioration of the gain medium by gold nanoparticles is successfully compensated by silica coating on the nanoparticles.

  • 28.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Chughtai, Adnan
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Photostability of lasing process from water solution of Rhodamine 6G with gold nanoparticles2012In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, no 1, p. 34-36Article in journal (Refereed)
    Abstract [en]

    We report the lasing performance and photobleaching of gain material containing a water solution of Rhodamine 6G dye and gold nanoparticles (NPs). In comparison to a pure dye solution, the investigated material demonstrated both enhancement and quenching of the lasing output, depending on the relative concentration of the gold NPs. Although the presence of NPs with an optimized concentration looks preferable in terms of the lasing output enhancement, such additives deteriorate the operational resource of the gain material; i.e., the photobleaching rate speeds up.

  • 29.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Hu, Jun
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Fluorescence quenching and photobleaching in Au/Rh6G nanoassemblies: impact of competition between radiative and non-radiative decay2011In: JOURNAL OF THE EUROPEAN OPTICAL SOCIETY-RAPID PUBLICATIONS, ISSN 1990-2573, Vol. 6, p. 11019-Article in journal (Refereed)
    Abstract [en]

    We report the study of fluorescence quenching from nanoassemblies formed by Rhodamine 6G and gold nanoparticles (Au NPs) of 2.6 nm radius. The presence of Au NPs induces long-term degradation of the photostability (photobleaching) of Rhodamine 6G used as a gain medium in a Fabry-Perot laser cavity. We found that the degradation gets profound when the Au NPs concentration is significantly increased. Calculation of the radiative rate and direct time-resolved measurement of the fluorescence decay indicates that both the decrease of radiative decay rate and increase of non-radiative decay rate are responsible for the fluorescence quenching and photostability degradation. An energy transfer from the dye molecules to gold nanoparticles is dominating within small distance between them and suppresses the quantum efficiency of Rhodamine 6G drastically. In a long time scale, the photobleaching rate was slowing down, and the laser output intensity reached a stabilized level which depends on the gold nanoparticles concentration.

  • 30.
    Eita, Mohamed
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    El Sayed, Ramy
    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.
    Optical properties of thin films of zinc oxide quantum dots and polydimethylsiloxane: UV-blocking and the effect of cross-linking2012In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 387, p. 135-140Article in journal (Refereed)
    Abstract [en]

    Thin films of polydimethylsiloxane (PDMS) and ZnO quantum dots (QDs) were built up as multilayers by spin-coating. The films are characterized by a UV-blocking ability that increases with increasing number of bilayers. Photoluminescence (PL) emission spectra of the thin films occur at 522 nm, which is the PL wavelength of the ZnO QDs dispersion, but with a lower intensity and a quantum yield (QY) less than 1% that of the dispersion. Cross-linking has introduced new features to the absorption spectra in that the absorption peak was absent. These changes were attributed to the morphological and structural changes revealed by transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR), respectively. TEM showed that the ZnO particle size in the film increased from 7 (+/- 2.7) nm to 16 (+/- 7.8) upon cross-linking. The FTIR spectra suggest that ZnO QDs are involved in the cross-linking of PDMS and that the surface of the ZnO QDs has been chemically modified.

  • 31.
    Eita, Mohamed
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Wagberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Spin-Assisted Multilayers of Poly(methyl methacrylate) and Zinc Oxide Quantum Dots for Ultraviolet-Blocking Applications2012In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 4, no 6, p. 2920-2925Article in journal (Refereed)
    Abstract [en]

    Thin UV-blocking films of poly(methyl methacrylate) (PMMA) and ZnO quantum dots (QDs) were built-up by spin-coating. Ellipsometry reveals average thicknesses of 9.5 and 8.6 nm per bilayer before and after heating at 100 degrees C for one hour, respectively. The surface roughness measured by Atomic force microscopy (AFM) was 3.6 and 8.4 nm for the one and ten bilayer films, respectively. The linear increase in thickness as well as the low surface roughness increment per bilayer indicates a stratified multilayer structure and a smooth interface without: aggregation. The absorption of UV radiation increased with increasing number of bilayers. At the same time, transmission was damped at wavelengths shorter than 375 nm. The thin films had a high and constant transparency in the visible region. Green-light emitting QDs could be detected by confocal microscopy at a concentration of 20% in a single layer of PMMA/ZnO. PMMA/ZnO QDs thin films are hydrophobic, as indicated by contact angle measurements.

  • 32.
    Eita, Mohamed
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Wagberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Thin Films of Zinc Oxide Nanoparticles and Poly(acrylic acid) Fabricated by the Layer-by-Layer Technique: a Facile Platform for Outstanding Properties2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 7, p. 4621-4627Article in journal (Refereed)
    Abstract [en]

    The incorporation of nanoparticles into polyelectrolytes thin films opens the way to a broad range of applications depending on the functionality of the nanoparticles. In this work, thin films of ZnO nanoparticles and poly(acrylic acid) (PAA) were built up using the layer-by-layer technique. The thickness of a 20-bilayer film is about 120 nm with a surface roughness of 22.9 nm as measured by atomic force microscopy (AFM). Thin ZnO/PAA films block UV radiation starting at a wavelength of 361 nm due to absorption by ZnO although the films are highly transparent. Due to their high porosity, these thin films show a broadband antireflection in the visible region, and thus they provide selective opacity in the UV region and enhanced transmittance in the visible region up to the near-infrared region. They are also superhydrophilic due to their high porosity and surface roughness.

  • 33. El-Sayed, R.
    et al.
    Ye, F.
    Asem, Heba
    KTH, School of Engineering Sciences (SCI), Applied Physics, Functional Materials, FNM.
    Ashour, Radwa
    KTH, School of Engineering Sciences (SCI), Applied Physics, Functional Materials, FNM.
    Zheng, W.
    Muhammed, Mamoun
    KTH, School of Engineering Sciences (SCI), Applied Physics, Functional Materials, FNM. Alexandria University, Egypt.
    Hassan, M.
    Importance of the surface chemistry of nanoparticles on peroxidase-like activity2017In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 491, no 1, p. 15-18Article in journal (Refereed)
    Abstract [en]

    We report the studies on origin of peroxidase-like activity for gold nanoparticles, as well as the impact from morphology and surface charge of nanoparticles. For this purpose, we have synthesized hollow gold nanospheres (HAuNS) and gold nanorods (AuNR) with different morphology and surface chemistry to investigate their influence on the catalytic activity. We found that citrate-capped HAuNS show catalyzing efficiency in oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) by hydrogen peroxide (H2O2) and it is superior to that of cetyltrimethylammonium bromide (CTAB)-capped AuNR. The kinetics of catalytic activities from HAuNS and AuNR were respectively studied under varied temperatures. The results indicated that surface chemistry rather than morphology of nanoparticles plays an important role in the catalytic reaction of substrate. Furthermore, influencing factors such as pH, amount of nanoparticle and H2O2 concentration were also investigated on HAuNS-catalyzed system. The great impact of nanoparticle surface properties on catalytic reactions makes a paradigm in constructing nanozymes as peroxidase mimic for sensing application.

  • 34. El-Sayed, Ramy
    et al.
    Eita, Mohamed
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Barrefelt, Åsa
    Ye, Fei
    Jain, Himanshu
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Fares, Mona
    Lundin, Arne
    Crona, Mikael
    Abu-Salah, Khalid
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Hassan, Moustapha
    Thermostable Luciferase from Luciola cruciate for Imaging of Carbon Nanotubes and Carbon Nanotubes Carrying Doxorubicin Using in Vivo Imaging System2013In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 13, no 4, p. 1393-1398Article in journal (Refereed)
    Abstract [en]

    In the present study, we introduce a novel method for in vivo imaging of the biodistribution of single wall carbon nanotubes (SWNTs) labeled with recombinant thermo-stable Luciola cruciata luciferase (LcL). In addition, we highlight a new application for green fluorescent proteins in which they are utilized as imaging moieties for SWNTs. Carbon nanotubes show great positive potential compared to other drug nanocarriers with respect to loading capacity, cell internalization, and biodegradability. We have also studied the effect of binding mode (chemical conjugation and physical adsorption) on the chemiluminescence activity, decay rate, and half-life. We have shown that through proper chemical conjugation of LcL to CNTs, LcL remained biologically active for the catalysis of D-luciferin in the presence of ATP to release detectable amounts of photons for in vivo imaging. Chemiluminescence of LcL allows imaging of CNTs and their cargo in nonsuperficial locations at an organ resolution with no need of an excitation source. Loading LcL-CNTs with the antitumor antibiotic doxorubicin did not alter their biological activity for imaging. In vivo imaging of LcL-CNTs has been carried out using "IVIS spectrum" showing the uptake of LcL-CNTs by different organs in mice. We believe that the LcL-CNT system is an advanced powerful tool for in vivo imaging and therefore a step toward the advancement of the nanomellicine field.

  • 35. Fathy, Marwa
    et al.
    El Nady, Jehan
    Muhammed, u1m5r8td
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Ebrahim, Shaker
    Soliman, Moataz B.
    Kashyout, Abd El-Hady B.
    Quasi-solid-state Electrolyte for Dye Sensitized Solar Cells Based on Nanofiber PMA-PVDF and PMA-PVDF/PEG Membranes2016In: International Journal of Electrochemical Science, ISSN 1452-3981, E-ISSN 1452-3981, Vol. 11, no 7, p. 6064-6077Article in journal (Refereed)
    Abstract [en]

    Novel electrospun membranes quasi-solid electrolytes based on blends of polymethylacrylate (PMA) - polyvinylidene fluoride (PVDF), and PMA-PVDF/PEG (polyethylene glycol) are prepared by electrospinning technique and applied as quasi-solid state electrolytes in dye sensitized solar cells (DSSCs). The membranes are characterized by Fourier transform infrared (FT-IR) spectrophotometer, differential scanning calorimeter (DSC), Scanning electron microscopy (SEM), and Electrochemical impedance spectroscopy. The crystallinity obtained from the DSC data increased with the increase of PVDF wt% in PMA-PVDF blend and then decreased for the PMA-PVDF/PEG membranes. The fully interconnected porous structure of the host polymer membranes of PMA-PVDF (4: 6 wt%) exhibited a high electrolyte uptake reached to similar to 265% and an ionic conductivity of 2.1x10(-3) S cm(-1), which is increased to 406.3%, and 3.2 x 10(-3) S cm(-1), respectively for PMA-PVDF/PEG (4: 6: 4 wt%) membrane. DSSC is assembled by PMA-PVDF(4: 6 wt%) and attained an overall energy conversion efficiency of 6.6% at light intensity of 100 mW cm(-2). The presence of 4 w% PEG in the electrolyte membrane increased the energy conversion efficiency to 7 % giving a promise candidate for scaling up this type of DSSCs.

  • 36.
    Fornara, Andrea
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Chiavarino, Annalisa
    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.
    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.
    PLGA-PEG multifunctional nanoparticles for simultaneous drug delivery and visualizationIn: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896XArticle in journal (Other academic)
  • 37.
    Fornara, Andrea
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Chiavarino, Annalisa
    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.
    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.
    PLGA-PEG multifunctional nanoparticles for simultaneous drug delivery and imaging by MRI and fluorescence microscopy2012In: Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2012, 2012, p. 4-7Conference paper (Refereed)
    Abstract [en]

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

  • 38.
    Fornara, Andrea
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Functional Materials, FNM (Closed 20120101).
    Johansson, Petter
    Petersson, Karolina
    Gustafsson, Stefan
    Qin, Jian
    Olsson, Eva
    Ilver, Dag
    Krozer, Anatol
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Functional Materials, FNM (Closed 20120101).
    Johansson, Christer
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Functional Materials, FNM (Closed 20120101).
    Tailored Magnetic Nanoparticles for Direct and Sensitive Detection of Biomolecules in Biological Samples2008In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 8, no 10, p. 3423-3428Article in journal (Refereed)
    Abstract [en]

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

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

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

  • 39.
    Fornara, Andrea
    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.
    Laurent, Sophie
    University of Mons.
    Muller, Robert
    University of Mons.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Bifunctional polylactide coated iron oxide nanoparticles for drug delivery and MRI contrast enhancementIn: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095Article in journal (Other academic)
  • 40.
    Fornara, Andrea
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Recalenda, Alberto
    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.
    Sugunan, Abhilash
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Fei, Ye
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Laurent, Sophie
    University of Mons.
    Muller, Robert
    University of Mons.
    Zou, Jing
    University of Tampere.
    Usama, Abo-RAmadan
    University of Helsinki.
    Toprak, Muhammet
    KTH, 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.
    Polymeric/inorganic multifunctional nanoparticles for simultaneous drug delivery and visualization2010In: Materials Research Society Symposium Proceedings, ISSN 0272-9172, E-ISSN 1946-4274, Vol. 1257Article in journal (Refereed)
    Abstract [en]

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

  • 41.
    Fornara, Andrea
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Vogt, Carmen
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Li, Shanghua
    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.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Synthesis, characterization and magneto-optical properties of transparent magnetic PMMA/nanoparticles compositeManuscript (preprint) (Other academic)
  • 42.
    Furberg, Richard
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Li, Shanghua
    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.
    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.
    Use of a novel nano- and micro-porous structure for enhanced boiling in a plate heat exchanger2008In: Proceedings of the 9th IEA heat pump conference, Zürich, CH, Zürich, CH: Academic Conferences Publishing, 2008Conference paper (Refereed)
  • 43.
    Furberg, Richard
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Li, Shanghua
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    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.
    Dendritically ordered nano-particles in a micro-porous structure for enhanced boiling2006In: Proceedings of 13th International Heat Transfer Conference, NAN-07, 2006, Vol. NAN-07Conference paper (Refereed)
    Abstract [en]

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

  • 44.
    Furberg, Richard
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Li, Shanghua
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Tuprak, MUHAMMET
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Muhammed, MAMOUN
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Porous layer2006Patent (Other (popular science, discussion, etc.))
  • 45.
    Furberg, Richard
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn E.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Li, Shanghua
    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.
    The Use of a Nano- and Microporous Surface Layer to Enhance Boiling in a Plate Heat Exchanger2009In: Journal of heat transfer, ISSN 0022-1481, E-ISSN 1528-8943, Vol. 131, no 10Article in journal (Refereed)
    Abstract [en]

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

  • 46.
    Gustafsson, Stefan
    et al.
    Department of Applied Physics, Chalmers University of Technology.
    Fornara, Andrea
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Petersson, Karolina
    Imego AB.
    Johansson, Christer
    Imego AB.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Olsson, Eva
    Department of Applied Physics, Chalmers University of Technology.
    Evolution of Structural and Magnetic Properties of Magnetite Nanoparticles for Biomedical Applications2010In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, no 5, p. 2278-2284Article in journal (Refereed)
    Abstract [en]

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

  • 47.
    Haghighi, Ehsan Bitaraf
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Saleemi, Mohsin
    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.
    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, Functional Materials, FNM.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Accurate basis of comparison for convective heat transfer in nanofluids2014In: International Communications in Heat and Mass Transfer, ISSN 0735-1933, E-ISSN 1879-0178, Vol. 52, p. 1-7Article in journal (Refereed)
    Abstract [en]

    Thermal conductivity and viscosity of alumina (Al2O3), zirconia (ZrO2), and titania (TiO2) nanofluids (NFs) were measured at 20°C. All the NF systems were water based and contained 9wt.% solid particles. Additionally, the heat transfer coefficients for these NFs were measured in a straight tube of 1.5m length and 3.7mm inner diameter. Based on the results, it can be stated that classical correlations, such as Shah and Gnielinski, for laminar and turbulent flow respectively, can be employed to predict convective heat transfer coefficients in NFs, if the accurate thermophysical properties are used in the calculations. Convective heat transfer coefficients for NFs were also compared with those of the base fluids using two different bases for the comparison, with contradictory results: while compared at equal Reynolds number, the heat transfer coefficients increased by 8-51%, whereas compared at equal pumping power the heat transfer coefficients decreased by 17-63%. As NFs have higher viscosity than the base fluids, equal Reynolds number requires higher volumetric flow, hence higher pumping power for the NFs. It is therefore strongly suggested that heat transfer results should be compared at equal pumping power and not at equal Reynolds number.

  • 48. He, Z.
    et al.
    Stiewe, C.
    Li, Shen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Platzek, D.
    Karpinski, G.
    Müller, E.
    Toprak, Muhammet
    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.
    Processing and characterization of nano-structured ZrO2/ CoSb3 thermoelectric composites2006Conference paper (Refereed)
    Abstract [en]

    The addition of ceramic inclusion to a thermoelectric matrix could reduce the thermal conductivity of the composite, which is attributed to phonon scattering on the generated interfaces. The electrical conductivity of the composite, however, could also be reduced due to additional charge carrier scattering. The performance of the thermoelectric composite, therefore, depends on the resulting ratio of electrical conductivity to thermal conductivity, which results from the entire scattering effects on phonons and charge carriers. In the present work, nano-sized ZrO2 powders of different contents, which were expected to minimize their scattering impact on charge carriers, were dispersed into submicron-sized CoSb3 powders via ball milling. The as-milled powders were consolidated into dense compacts by hot pressing. The phase, the microstructure, and the thermoelectric properties of the prepared compacts were characterized. The correlation of phase purity, microstructure, and thermoelectric properties (electrical conductivity, thermal conductivity, and ratio of electrical conductivity to thermal conductivity), with the ceramic content and sintering temperature is presented. The results show how the performance of the investigated thermoelectric composites can be affected by the dispersion of nano-sized ceramic inclusions. It is noted that the selection of appropriate inclusion content is crucial to maintaining or improving the ratio of electrical conductivity to thermal conductivity.

  • 49. He, Zeming
    et al.
    Stiewe, Christian
    Platzek, Dieter
    Karpinski, Gabriele
    Mueller, Eckhard
    Li, Shanghua
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    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.
    Effect of ceramic dispersion on thermoelectric properties of nano ZrO2/CoSb3 composites2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 4, p. 043707-Article in journal (Refereed)
    Abstract [en]

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

  • 50. He, Zeming
    et al.
    Stiewe, Christian
    Platzek, Dieter
    Karpinski, Gabriele
    Mueller, Eckhard
    Li, Shanghua
    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.
    Nano ZrO2/CoSb3 composites with improved thermoelectric figure of merit2007In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 18, no 23, p. 235602-Article in journal (Refereed)
    Abstract [en]

    Nano ZrO2/CoSb3 composites with different ZrO 2 contents were prepared using hot pressing. The phase purity, the microstructure and the temperature-dependent transport parameters of the composites were investigated. The dimensionless figure of merit (ZT) of 0.18 of the non-dispersed CoSb3 preponderates the maximal value (0.17) of pure CoSb3 reported in the literature, which is attributed to the prepared sample having higher electrical conductivity due to the existence of a small amount of metallic Sb and lower thermal conductivity due to the fine-grained structure. Compared to non-dispersed CoSb3, a further improvement of 11% on ZT (0.20) was achieved in the composite with 0.05ZrO 2 inclusions, which resulted from the enhanced ratio of electrical conductivity to thermal conductivity and the Seebeck coefficient. The nanodispersion method provides an effective approach to improving a material's thermoelectric properties and performance.

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