Change search
Refine search result
1234567 1 - 50 of 1912
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    A. M. Naiini, Maziar
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Horizontal Slot Waveguides for Silicon Photonics Back-End Integration2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents the development of integrated silicon photonic devices. These devices are compatible with the present and near future CMOS technology. High-khorizontal grating couplers and waveguides are proposed. This work consists of simulations and device design, as well as the layout for the fabrication process, device fabrication, process development, characterization instrument development and electro-optical characterizations.

    The work demonstrates an alternative solution to costly silicon-on-insulator photonics. The proposed solution uses bulk silicon wafers and thin film deposited waveguides. Back-end deposited horizontal slot grating couplers and waveguides are realized by multi-layers of amorphous silicon and high-k materials.

    The achievements of this work include: A theoretical study of fully etched slot grating couplers with Al2O3, HfO2 and AIN, an optical study of the high-k films with spectroscopic ellipsometry, an experimental demonstration of fully etched SiO2 single slot grating couplers and double slot Al2O3 grating couplers, a practical demonstration of horizontal double slot high-k waveguides, partially etched Al2O3 single slot grating couplers, a study of a scheme for integration of the double slot Al2O3  waveguides with selectively grown germanium PIN photodetectors, realization of test chips for the integrated germanium photodetectors, and study of integration with graphene photodetectors through embedding the graphene into a high-k slot layer.

    From an application point of view, these high-k slot waveguides add more functionality to the current silicon photonics. The presented devices can be used for low cost photonics applications. Also alternative optical materials can be used in the context of this photonics platform.

    With the robust design, the grating couplers result in improved yield and a more cost effective solution is realized for integration of the waveguides with the germanium and graphene photodetectors.

     

     

     

     

  • 2.
    Aarstad, Olav
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Heggset, Ellinor B.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Pedersen, Ina Sander
    NTNU Norwegian University of Science and Technology, Norway.
    Björnöy, Sindre H.
    NOBIPOL,NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Strand, Berit L.
    NTNU Norwegian University of Science and Technology, Norway.
    Mechanical properties of composite hydrogels of alginate and cellulose nanofibrils2017In: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 9, no 8, 378Article in journal (Refereed)
    Abstract [en]

    Alginate and cellulose nanofibrils (CNF) are attractive materials for tissue engineering and regenerative medicine. CNF gels are generally weaker and more brittle than alginate gels, while alginate gels are elastic and have high rupture strength. Alginate properties depend on their guluronan and mannuronan content and their sequence pattern and molecular weight. Likewise, CNF exists in various qualities with properties depending on, e.g., morphology and charge density. In this study combinations of three types of alginate with different composition and two types of CNF with different charge and degree of fibrillation have been studied. Assessments of the composite gels revealed that attractive properties like high rupture strength, high compressibility, high gel rigidity at small deformations (Young’s modulus), and low syneresis was obtained compared to the pure gels. The effects varied with relative amounts of CNF and alginate, alginate type, and CNF quality. The largest effects were obtained by combining oxidized CNF with the alginates. Hence, by combining the two biopolymers in composite gels, it is possible to tune the rupture strength, Young’s modulus, syneresis, as well as stability in physiological saline solution, which are all important properties for the use as scaffolds in tissue engineering.

  • 3.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Zhu, Yi
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Pin-on-disc study of the effects of railway friction modifiers on airborne wear particles from wheel-rail contact2013In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 60, 136-139 p.Article in journal (Refereed)
    Abstract [en]

    Knowledge of wheel–rail interaction is crucial to wheel and rail maintenance. In this interaction, some of theworn-off material is transformed into airborne particles. Although such wear is well understood, few studiestreat the particles generated. We investigated friction modifiers' effects on airborne particles characteristicsgenerated in wheel-rail contacts in laboratory conditions. Pin-on-disc machine testing with a round-head pinloaded by a dead weight load 40 N simulated maximum contact pressure over 550 MPa. Airborne particlecharacteristics were investigated in dry contacts and in ones lubricated with biodegradable rail grease andwater- and oil-based friction modifiers. The number of particles declined with the grease; the number ofultrafine particles increased with the water-based friction modifier, mainly due to water vaporization.

  • 4.
    Abdellah, Mohamed
    et al.
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden.;South Valley Univ, Qena Fac Sci, Dept Chem, Qena 83523, Egypt..
    Poulsen, Felipe
    Univ Copenhagen, Dept Chem, DK-2100 Copenhagen, Denmark..
    Zhu, Qiushi
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden..
    Zhu, Nan
    Tech Univ Denmark, Dept Chem, Kemitorvet Bldg 207, DK-2800 Lyngby, Denmark.;Dalian Univ Technol, Zhang Dayu Sch Chem, Dalian 116024, Peoples R China..
    Zidek, Karel
    Acad Sci Czech Republ, Inst Plasma Phys, Reg Ctr Special Opt & Optoelect Syst TOPTEC, Za Slovankou 1782-3, Prague 18200 8, Czech Republic..
    Chabera, Pavel
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden..
    Corti, Annamaria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Hansen, Thorsten
    Univ Copenhagen, Dept Chem, DK-2100 Copenhagen, Denmark..
    Chi, Qijin
    Tech Univ Denmark, Dept Chem, Kemitorvet Bldg 207, DK-2800 Lyngby, Denmark..
    Canton, Sophie E.
    DESY, Attosecond Sci Grp, Notkestr 85, D-22607 Hamburg, Germany.;ELI HU Nonprofit Ltd, ELI ALPS, Dugonics Ter 13, H-6720 Szeged, Hungary..
    Zheng, Kaibo
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden.;Qatar Univ, Coll Engn, Gas Proc Ctr, POB 2713, Doha, Qatar..
    Pullerits, Tonu
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden..
    Drastic difference between hole and electron injection through the gradient shell of CdxSeyZn1−xS1−y quantum dots2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 34, 12503-12508 p.Article in journal (Refereed)
    Abstract [en]

    Ultrafast fluorescence spectroscopy was used to investigate the hole injection in CdxSeyZn1-xS1-y gradient core-shell quantum dot (CSQD) sensitized p-type NiO photocathodes. A series of CSQDs with a wide range of shell thicknesses was studied. Complementary photoelectrochemical cell measurements were carried out to confirm that the hole injection from the active core through the gradient shell to NiO takes place. The hole injection from the valence band of the QDs to NiO depends much less on the shell thickness when compared to the corresponding electron injection to n-type semiconductor (ZnO). We simulate the charge carrier tunneling through the potential barrier due to the gradient shell by numerically solving the Schrodinger equation. The details of the band alignment determining the potential barrier are obtained from X-ray spectroscopy measurements. The observed drastic differences between the hole and electron injection are consistent with a model where the hole effective mass decreases, while the gradient shell thickness increases.

  • 5.
    Abedin, Ahmad
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Noroozi, Mohammad
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Primetzhofer, Daniel
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Radamson, Henry.H
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    GeSnSi CVD Epitaxy using Silane, Germane, Digermane, and Tin tetrachlorideArticle in journal (Refereed)
    Abstract [en]

    In this study, strain relaxed and compressive strained Ge1-x-ySnxSiy (0.015≤x≤0.15 and 0≤y≤0.15) layers were epitaxially grown on Si substrate in a chemical vapor deposition reactor at atmospheric pressure. Digermane (Ge2H6) and germane (GeH4) were used as Ge precursors and tin tetrachloride (SnCl4) was used as Sn precursor. The growth temperature was kept below 400ᵒC to suppress Sn out diffusion. The layers crystal quality and strain were characterized using XRD, high resolution reciprocal lattice mapping and transmission electron microscopy and the surface morphology was investigated by atomic force microscopy (AFM). Furthermore, the low temperature epitaxial growth up to 15% Si atoms incorporation in Ge0.94Sn0.06 was demonstrated by adding silane (SiH4) as Si precursor. Sn contents calculated from high resolution XRD patterns were confirmed by Rutherford backscattering spectroscopy which shows that Sn atoms are mostly positioned in substitutional sites. AFM analysis showed below 1nm surface roughness for both strained and strain relaxed GeSn layers which make the promising materials for photonics and electronics applications.

  • 6. Abermann, S.
    et al.
    Efavi, J. K.
    Sjoblom, G.
    Lemme, Max C.
    AMO GmbH, AMICA, Aachen, Germany.
    Olsson, J.
    Bertagnolli, E.
    Processing and evaluation of metal gate/high-kappa/Si capacitors incorporating Al, Ni, TiN, and Mo as metal gate, and ZrO2 and HfO2 as high-kappa dielectric2007In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 84, no 5-8, 1635-1638 p.Article in journal (Refereed)
    Abstract [en]

    We evaluate various metal gate/high-K/Si capacitors by their resulting electrical characteristics. Therefore, we process MOS gate stacks incorporating aluminium (Al), nickel (Ni), titanium-nitride (TiN), and molybdenum (Mo) as the gate material, and metal organic chemical vapour deposited (MOCVD) ZrO2 and HfO2 as the gate dielectric, respectively. The influence of the processing sequence - especially of the thermal annealing treatment - on the electrical characteristics of the various gate stacks is being investigated. Whereas post metallization annealing in forming gas atmosphere improves capacitance-voltage behaviour (due to reduced interface-, and oxide charge density), current-voltage characteristics degrade due to a higher leakage current after thermal treatment at higher temperatures. The Flatband-voltage values for the TiN-, Mo-, and Ni-capacitors indicate mid-gap pinning of the metal gates, however, Ni seems to be thermally unstable on ZrO2, at least within the process scheme we applied.

  • 7. Abermann, S.
    et al.
    Efavi, J.
    Sjoblom, G.
    Lemme, Max C.
    AMO GmbH, AMICA, Aachen, Germany.
    Olsson, J.
    Bertagnolli, E.
    Impact of Al-, Ni-, TiN-, and Mo-metal gates on MOCVD-grown HfO2 and ZrO2 high-k dielectrics2007In: Microelectronics and reliability, ISSN 0026-2714, E-ISSN 1872-941X, Vol. 47, no 4-5, 536-539 p.Article in journal (Refereed)
    Abstract [en]

    In this work we compare the impacts of nickel (Ni), titanium-nitride (TiN), molybdenum (Mo), and aluminium (Al), gates on MOS capacitors incorporating HfO2- or ZrO2-dielectrics. The primary focus lies on interface trapping, oxide charging, and thermodynamical stability during different annealing steps of these gate stacks. Whereas Ni, Mo, and especially TIN are investigated as most promising candidates for future CMOS devices, Al acted as reference gate material to benchmark the parameters. Post-metallization annealing of both, TiN- and Mo-stacks, resulted in very promising electrical characteristics. However, gate stacks annealed at temperatures of 800 degrees C or 950 degrees C show thermodynamic instability and related undesirable high leakage currents.

  • 8. Abermann, S.
    et al.
    Sjoblom, G.
    Efavi, J.
    Lemme, Max C.
    AMO GmbH, AMICA, Aachen, Germany.
    Olsson, J.
    Bertagnolli, E.
    Comparative study on the impact of TiN and Mo metal gates on MOCVD-grown HfO2 and ZrO2 high-kappa dielectrics for CMOS technology2007In: Physics of Semiconductors, Pts A and B, 2007, 293-294 p.Conference paper (Refereed)
    Abstract [en]

    We compare metal oxide semiconductor capacitors, investigating Titanium-Nitride and Molybdenum as gate materials, as well as metal organic chemical vapor deposited ZrO2 and HfO2 as high-kappa dielectrics, respectively. The impact of different annealing steps on the electrical characteristics of the various gate stacks is a further issue. The positive effect of post metallization annealing in forming gas atmosphere as well as observed mid-gap pinning of TiN and Mo metal gates is presented.

  • 9.
    Abrikossova, Natalia
    et al.
    Division of Molecular Surface Physics and Nanoscience, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden .
    Skoglund, Caroline
    Division of Molecular Surface Physics and Nanoscience, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden; Division of Clinical Medicine, Department of Biomedicine, Örebro University, Örebro, Sweden.
    Ahrén, Maria
    Division of Molecular Surface Physics and Nanoscience, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Bengtsson, Torbjörn
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Division of Clinical Medicine, Department of Biomedicine.
    Uvdal, Kajsa
    Division of Molecular Surface Physics and Nanoscience, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Effects of gadolinium oxide nanoparticles on the oxidative burst from human neutrophil granulocytes2012In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, no 27, 275101Article in journal (Refereed)
    Abstract [en]

    We have previously shown that gadolinium oxide (Gd2O3) nanoparticles are promising candidates to be used as contrast agents in magnetic resonance (MR) imaging applications. In this study, these nanoparticles were investigated in a cellular system, as possible probes for visualization and targeting intended for bioimaging applications. We evaluated the impact of the presence of Gd2O3 nanoparticles on the production of reactive oxygen species (ROS) from human neutrophils, by means of luminol-dependent chemiluminescence. Three sets of Gd2O3 nanoparticles were studied, i.e. as synthesized, dialyzed and both PEG-functionalized and dialyzed Gd2O3 nanoparticles. In addition, neutrophil morphology was evaluated by fluorescent staining of the actin cytoskeleton and fluorescence microscopy. We show that surface modification of these nanoparticles with polyethylene glycol (PEG) is essential in order to increase their biocompatibility. We observed that the as synthesized nanoparticles markedly decreased the ROS production from neutrophils challenged with prey (opsonized yeast particles) compared to controls without nanoparticles. After functionalization and dialysis, more moderate inhibitory effects were observed at a corresponding concentration of gadolinium. At lower gadolinium concentration the response was similar to that of the control cells. We suggest that the diethylene glycol (DEG) present in the as synthesized nanoparticle preparation is responsible for the inhibitory effects on the neutrophil oxidative burst. Indeed, in the present study we also show that even a low concentration of DEG, 0.3%, severely inhibits neutrophil function. In summary, the low cellular response upon PEG-functionalized Gd2O3 nanoparticle exposure indicates that these nanoparticles are promising candidates for MR-imaging purposes.

  • 10. Acciaro, R.
    et al.
    Aulin, C.
    RISE, Innventia.
    Wågberg, L.
    Lindström, T.
    RISE, Innventia.
    Claesson, P.M.
    Varga, I.
    Investigation of the formation structure and release characteristics of self-assembled composite films of cellulose nanofibrils and temperature responsive microgels2011In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, no 4, 1369-1377 p.Article in journal (Refereed)
  • 11.
    Afrasiabi, Roodabeh
    KTH, School of Information and Communication Technology (ICT).
    Hysteresis and Time-delay in the pH Response of Al2O3 and SiO2-gated Silicon Nanoribbon FET SensorsManuscript (preprint) (Other academic)
    Abstract [en]

    The conventional ion-sensitive field-effect transistor (ISFET) with SiO2 as the insulator of choice has been used as an electrochemical sensor to measure ion concentrations in solutions for many decades. With the ongoing progress in use of silicon nanoribbon (SiNR) FET sensors for fast reliable sensing and the recent demand for pH-sensing technologies in biological applications, it is important to identify the true pH response of the device. However, it has become much more difficult to achieve reliable results across a broad range of pH using SiO2-gated SiNR FET sensors and limitations such as long term drift and hysteresis (also referred to as memory effects) during pH measurements need to be addressed. In this work, we have investigated the electrochemical pH response behavior of silicon oxide-gated SiNR FET sensors and compared it with similar devices (same NR size) but with Al2O3 as the gate oxide. Our studies show that devices passivated with SiO2 show a large hysteresis in the pH response both in acidic and in basic direction, whereas Al2O3 surfaces show slight hysteresis and only in the acidic pH range. Furthermore, in case of SiO2, the total response-time after a pH change appears to be a combination of a fast transient and a slow drift which is related both to the type of oxide and the concentration of the background electrolyte. Consequently, to minimize errors in pH measurements caused by hysteresis and delayed response, we advise performing the measurements at low ionic concentrations and preferably to replace SiO2 by Al2O3 as the gate oxide. In biological applications, we also recommend the integration of an on-chip reference nanoribbon FET for real-time monitoring of problems such as long-term drift and slow response.

  • 12.
    Afrasiabi, Roodabeh
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Silicon Nanoribbon FET Sensors: Fabrication, Surface Modification and Microfluidic Integration2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Over the past decade, the field of medical diagnostics has seen an incredible amount of research towards the integration of one-dimensional nanostructures such as carbon nanotubes, metallic and semiconducting nanowires and nanoribbons for a variety of bio-applications. Among the mentioned one-dimensional structures, silicon nanoribbon (SiNR) field-effect transistors (FET) as electro-chemical nanosensors hold particular promise for label-free, real-time and sensitive detection of biomolecules using affinity-based detection. In SiNR FET sensors, electrical transport is primarily along the nanoribbon axis in a thin sheet (< 30 nm) serving as the channel. High sensitivity is achieved because of the large surface-to-volume ratio which allows analytes to bind anywhere along the NR affecting the entire conductivity by their surface charge. Unfortunately, sensitivity without selectivity is still an ongoing issue and this thesis aims at addressing the detection challenges and further proposing effective developments, such as parallel and multiple detection through using individually functionalized SiNRs.We present here a comprehensive study on design, fabrication, operation and device performance parameters for the next generation of SiNR FET sensors towards multiplexed, label-free detection of biomolecules using an on-chip microfluidic layer which is based on a highly cross-linked epoxy. We first study the sensitivity of different NR dimensions followed by analysis of the drift and hysteresis effects. We have also addressed two types of gate oxides (namely SiO2 and Al2O3) which are commonly used in standard CMOS fabrication of ISFETs (Ion sensitive FET). Not only have we studied and compared the hysteresis and response-time effects in the mentioned two types of oxides but we have also suggested a new integrated on-chip reference nanoribbon/microfluidics combination to monitor the long-term drift in the SiNR FET nanosensors. Our results show that compared to Al2O3, silicon-oxide gated SiNR FET sensors show high hysteresis and slow-response which limit their performance only to background electrolytes with low ionic strength. Al2O3 on the other hand proves more promising as the gate-oxide of choice for use in nanosensors. We have also illustrated that the new integrated sensor NR/Reference NR can be utilized for real-time monitoring of the above studied sources of error during pH-sensing. Furthermore, we have introduced a new surface silanization (using 3-aminopropyltriethoxysilane) method utilizing microwave-assisted heating which compared to conventional heating, yields an amino-terminated monolayer with high surface coverage on the oxide surface of the nanoribbons. A highly uniform and dense monolayer not only reduces the pH sensitivity of the bare-silicon oxide surface in a physiological media but also allows for more receptors to be immobilized on the surface. Protocols for surface functionalization and biomolecule immobilization were evaluated using model systems. Selective spotting of receptor molecules can be used to achieve localized functionalization of individual SiNRs, opening up opportunities for multiplexed detection of analytes.Additionally, we present here a novel approach by integrating droplet-based microfluidics with the SiNR FET sensors. Using the new system we are able to successfully detect trains of droplets with various pH values. The integrated system enables a wide range of label-free biochemical and macromolecule sensing applications based on detection of biological events such as enzyme-substrate interactions within the droplets.

  • 13.
    Afrasiabi, Roodabeh
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Jokilaakso, Nima
    KTH, School of Biotechnology (BIO), Protein Technology.
    Schmidt, Torsten
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Eriksson Karlström, Amelie
    KTH, School of Biotechnology (BIO), Protein Technology.
    Linnros, Jan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Microwave-assisted silanization of SiNW-FET: characterization and effect on sensing propertiesManuscript (preprint) (Other academic)
  • 14.
    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, 1551-1556 p.Article 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.

  • 15.
    Afrasiabi, Roodabeh
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Söderberg, Lovisa M.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Joensson, Haakan N.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Björk, Per
    Svahn Andersson, Helene
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Linnros, Jan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Integration of a Droplet-Based Microfluidic System and Silicon Nanoribbon FET Sensor2016In: Micromachines, ISSN 2072-666X, E-ISSN 2072-666X, Vol. 7, no 8Article in journal (Refereed)
    Abstract [en]

    We present a novel microfluidic system that integrates droplet microfluidics with a silicon nanoribbon field-effect transistor (SiNR FET), and utilize this integrated system to sense differences in pH. The device allows for selective droplet transfer to a continuous water phase, actuated by dielectrophoresis, and subsequent detection of the pH level in the retrieved droplets by SiNR FETs on an electrical sensor chip. The integrated microfluidic system demonstrates a label-free detection method for droplet microfluidics, presenting an alternative to optical fluorescence detection. In this work, we were able to differentiate between droplet trains of one pH-unit difference. The pH-based detection method in our integrated system has the potential to be utilized in the detection of biochemical reactions that induce a pH-shift in the droplets.

  • 16.
    Ahlberg, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Zhang, Zhibin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Nyberg, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Defect formation in graphene during low-energy ion bombardment2016In: APL Materials, ISSN 2166-532X, Vol. 4, no 4, 046104Article in journal (Refereed)
    Abstract [en]

    This letter reports on a systematic investigation of sputter induced damage in graphene caused by low energy Ar+ ion bombardment. The integral numbers of ions per area (dose) as well as their energies are varied in the range of a few eV's up to 200 eV. The defects in the graphene are correlated to the dose/energy and different mechanisms for the defect formation are presented. The energetic bombardment associated with the conventional sputter deposition process is typically in the investigated energy range. However, during sputter deposition on graphene, the energetic particle bombardment potentially disrupts the crystallinity and consequently deteriorates its properties. One purpose with the present study is therefore to demonstrate the limits and possibilities with sputter deposition of thin films on graphene and to identify energy levels necessary to obtain defect free graphene during the sputter deposition process. Another purpose is to disclose the fundamental mechanisms responsible for defect formation in graphene for the studied energy range.

  • 17.
    Ahlberg, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Seung, Hee Jeong
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jiao, Mingzhi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Graphene as a Diffusion Barrier in Galinstan-Solid Metal Contacts2014In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 61, no 8, 2996-3000 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents the use of graphene as a diffusion barrier to a eutectic Ga-In-Sn alloy, i.e., galinstan, for electrical contacts in electronics. Galinstan is known to be incompatible with many conventional metals used for electrical contacts. When galinstan is in direct contact with Al thin films, Al is readily dissolved leading to the formation of Al oxides present on the surface of the galinstan droplets. This reaction is monitored ex situ using several material analysis methods as well as in situ using a simple circuit to follow the time-dependent resistance variation. In the presence of a multilayer graphene diffusion barrier, the Al-galinstan reaction is effectively prevented for galinstan deposited by means of drop casting. When deposited by spray coating, the high-impact momentum of the galinstan droplets causes damage to the multilayer graphene and the Al-galinstan reaction is observed at some defective spots. Nonetheless, the graphene barrier is likely to block the formation of Al oxides at the Al/galinstan interface leading to a stable electrical current in the test circuit.

  • 18.
    Ahlström, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Characterizing the state of water in an amorphous magnesium carbonate using Dielectric spectroscopy2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the industry of today, materials which can adsorb and hold large amounts of water are playing an important role. Here, the free and bound water carrying capacity of an amorphous magnesium carbonate is investigated. It is also determined how these parameters depend on the relative humidity of the surrounding environment. To do this, the technique of dielectric spectroscopy is employed. Along with the water binding properties, the concentration of charge carriers and the diffusion coefficient was determined. A smaller part of around 10-30 % of the water adsorbed was shown to behave as free water in the material. The concentration of charge carriers was calculated to be in an order of magnitude of 1018-1022 m-3 for the higher relative humidity environments. The diffusion coefficient was shown to be about 5*10-9 m2/s for the adsorption spectrum. This value is in good agreement with the value for OH- ions in water.

  • 19.
    Ahmadi, Majid
    et al.
    University of Puerto Rico.
    Sahoo, Satyaprakash
    University of Puerto Rico.
    Younesi, Reza
    Technical University of Denmark.
    Gaur, Anand P. S.
    Katiyar, Ram S.
    Guinel, Maxime J-F
    WO3 nano-ribbons: their phase transformation from tungstite (WO3·H2O) to tungsten oxide (WO3)2014In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, no 17, 5899-5909 p.Article in journal (Refereed)
  • 20.
    Ahmadi, Majid
    et al.
    University of Puerto Rico.
    Younesi, Reza
    Technical University of Denmark.
    Guinel, Maxime J-F.
    University of Puerto Rico.
    Synthesis of tungsten oxide nanoparticles using a hydrothermal method at ambient pressure2014In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 29, no 13, 1424-1430 p.Article in journal (Refereed)
  • 21. Ahmed, Aseel Bala
    et al.
    Jibril, B.
    Danwittayakul, S.
    Dutta, Joydeep
    Sultan Qaboos Univ, Water Res Ctr, Chair Nanotechnol, Muscat, Oman.
    Microwave-enhanced degradation of phenol over Ni-loaded ZnO nanorods catalyst2014In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 156-157, 456-465 p.Article in journal (Refereed)
    Abstract [en]

    Nickel was loaded onto hydrothermally-grown ZnO nanorods on cordierite substrates and tested as catalysts in microwave-enhanced degradation of phenol from its aqueous solution (100 ppm) at 70 degrees C. Effects of metal loadings (1, 10 and 20 mM impregnation solutions) on the degradation of phenol in aqueous solution was investigated. The catalyst performances were monitored based on phenol degradation, product distributions and carbon dioxide (CO2) evolutions. Based on the type of the catalysts, two different mechanistic pathways for the decomposition were observed-through catechol and/or hydroquinone as intermediates. It was found that the 10mM nickel loaded sample catalyzed the degradation through one pathway with hydroquinone as the benzenediol intermediate formed, while the 20 mM nickel impregnated sample catalyzed the reaction through two pathways, producing catechol as well as hydroquinone by products. These differences in reaction pathways were attributed to the variation in the composition of the nickel compounds and surface structures between the two catalysts. Furthermore, the effect of hydrogen peroxide (H2O2) as an oxidant was explored. It was found that although addition of H2O2 led to an increase in the degree of phenol degradation, it also led to enhanced catalyst leaching. There was also an increase in CO2 evolution due to the addition of H2O2. It was observed that 20 mM nickel-loaded sample without the addition of H2O2 exhibited optimum performance in terms of phenol degradation and CO2 evolution with no drawback of catalyst leaching. Catalytic microwave enhanced degradation is an effective means for the removal of dissolved organic compounds from wastewater.

  • 22. Ahmed, Towfiq
    et al.
    Haraldsen, Jason T.
    Rehr, John J.
    Di Ventra, Massimiliano
    Schuller, Ivan
    Balatsky, Alexander V.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Correlation dynamics and enhanced signals for the identification of serial biomolecules and DNA bases2014In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 25, no 12, 125705- p.Article in journal (Refereed)
    Abstract [en]

    Nanopore-based sequencing has demonstrated a significant potential for the development of fast, accurate, and cost-efficient fingerprinting techniques for next generation molecular detection and sequencing. We propose a specific multilayered graphene-based nanopore device architecture for the recognition of single biomolecules. Molecular detection and analysis can be accomplished through the detection of transverse currents as the molecule or DNA base translocates through the nanopore. To increase the overall signal-to-noise ratio and the accuracy, we implement a new 'multi-point cross-correlation' technique for identification of DNA bases or other molecules on the single molecular level. We demonstrate that the cross-correlations between each nanopore will greatly enhance the transverse current signal for each molecule. We implement first-principles transport calculations for DNA bases surveyed across a multilayered graphene nanopore system to illustrate the advantages of the proposed geometry. A time-series analysis of the cross-correlation functions illustrates the potential of this method for enhancing the signal-to-noise ratio. This work constitutes a significant step forward in facilitating fingerprinting of single biomolecules using solid state technology.

  • 23. Ahrentorp, Fredrik
    et al.
    Blomgren, Jakob
    Jonasson, Christian
    Sarwe, Anna
    Sepehri, Sobhan
    Eriksson, Emil
    Kalaboukhov, Alexei
    Jesorka, Aldo
    Winkler, Dag
    Schneiderman, Justin F.
    Nilsson, Mats
    Albert, Jan
    Gómez de La Torre, Teresa Zardán
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Johansson, Christer
    Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils2017In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 427, no Supplement C, 14-18 p.Article in journal (Refereed)
    Abstract [en]

    Abstract We use functionalized iron oxide magnetic multi-core particles of 100nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75min of amplification we obtain an average RCA coil diameter of about 1µm. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200µL) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.

  • 24. Ahrentorp, Fredrik
    et al.
    Blomgren, Jakob
    Jonasson, Christian
    Sarwe, Anna
    Sepehri, Sobhan
    Eriksson, Emil
    Kalaboukhov, Alexei
    Jesorka, Aldo
    Winkler, Dag
    Schneiderman, Justin F.
    Nilsson, Mats
    Albert, Jan
    Zardán Gómez de la Torre, Teresa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Johansson, Christer
    Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils2016In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 427, 14-18 p.Article in journal (Refereed)
    Abstract [en]

    We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 µm. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 µL) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.

  • 25.
    Aili, Daniel
    et al.
    Imperial College London, U.K..
    Mager, M
    Imperial College London, U.K..
    Roche, David
    Imperial College London, U.K..
    Stevens, Molly
    Imperial College London, U.K..
    Hybrid Nanoparticle-Liposome Detection of Phospholipase Activity2011In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 11, no 4, 1401-1405 p.Article in journal (Refereed)
    Abstract [en]

    A flexible nanoparticle-based phospholipase (PL) assay is demonstrated in which the enzymatic substrate is decoupled from the nanoparticle surface. Liposomes are loaded with a polypeptide that is designed to heteroassociate with a second polypeptide immobilized on gold nanoparticies. Release of this polypeptide from the liposornes, triggered by PL, induces a folding-dependent nanoparticle bridging aggregation. The colorimetric response from this aggregation enables straightforward and continuous detection of PL in the picomolar range. The speed, specificity, and flexibility of this assay make it appropriate for a range of applications, from point of care diagnostics to high throughput pharmaceutical screening.

  • 26.
    Aili, Daniel
    et al.
    Imperial College London, UK .
    Stevens, Molly M.
    Imperial College London, UK .
    Bioresponsive peptide-inorganic hybrid nanomaterials2010In: Chemical Society Reviews, ISSN 0306-0012, E-ISSN 1460-4744, Vol. 39, no 9, 3358-3370 p.Article, review/survey (Refereed)
    Abstract [en]

    Bioanalytical techniques that enable simple, fast and reliable high sensitivity monitoring of biomolecular interactions are of immense importance for diagnostics and drug development. This tutorial review provides an overview of recent progress in the development of peptide-based hybrid nanomaterials that transduce molecular interactions by exploiting the optical and magnetic properties of nanoparticles. Peptides have emerged as an interesting alternative to conventional biomolecular receptors, such as antibodies, and are facilitating the design of responsive hybrid nanomaterials that are both robust and sensitive for biodiagnostic applications.

  • 27.
    Akhtar, Sultan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Rubino, Stefano
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    A simple TEM method for fast thickness characterization of suspendedgraphene flakesManuscript (preprint) (Other academic)
  • 28.
    Akner-Koler, Cheryl
    University College of Arts, Crafts and Design, The Department of Design, Crafts and Art (DKK).
    A Note on Nano (FormGiving)2015In: Radical Re Re Re Re Re Rethinking / [ed] Maria Lantz, Staffan Lundgren, Stockholm: Konstfack / University College of Arts, Crafts & Desi , 2015, 1 uppl., 128-133 p.Chapter in book (Other academic)
  • 29. Al Alawai, Reem
    et al.
    Laxman, karthik
    Dastgir, Sarim
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM. Sultan Qaboos University, , Oman.
    Role of bonding mechanisms during transfer hydrogenation reaction on heterogeneous catalysts of platinum nanoparticles supported on zinc oxide nanorods2016In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, 200-206 p.Article in journal (Refereed)
    Abstract [en]

    For supported heterogeneous catalysis, the interface between a metal nanoparticle and the support plays an important role. In this work the dependency of the catalytic efficiency on the bonding chemistry of platinum nanoparticles supported on zinc oxide (ZnO) nanorods is studied. Platinum nanoparticles were deposited on ZnO nanorods (ZnO NR) using thermal and photochemical processes and the effects on the size, distribution, density and chemical state of the metal nanoparticles upon the catalytic activities are presented. The obtained results indicate that the bonding at Pt-ZnO interface depends on the deposition scheme which can be utilized to modulate the surface chemistry and thus the activity of the supported catalysts. Additionally, uniform distribution of metal on the catalyst support was observed to be more important than the loading density. It is also found that oxidized platinum Pt(IV) (platinum hydroxide) provided a more suitable surface for enhancing the transfer hydrogenation reaction of cyclohexanone with isopropanol compared to zero valent platinum. Photochemically synthesized ZnO supported nanocatalysts were efficient and potentially viable for upscaling to industrial applications.

  • 30.
    Alam, Md Khorshed
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Fabrication of surface enhanced Raman spectroscopy (SERS) active substrates based on vertically aligned nitrogen doped carbon nanotube forest2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work describes the fabrication and surface enhanced Raman spectroscopy (SERS) characterization of vertically aligned nitrogen (N) doped multi walled carbon nanotube (MWCNT) forests coated by silver (Ag) and gold (Au) nanoparticles. In the present work, the CNT forests were grown from a catalyst metal layer by the chemical vapor deposition (CVD) process at temperature of 800 oC and a physical vapor deposition (PVD) and annealing processes were applied subsequently for the evaporation and diffusion of noble metal nanoparticles on the forest.

    Transistor patterning of 20, 50 and 100 μm were made onto the silicon-oxide (SiO2) wafers through the photolithography process with and without depositing a thickness of 10 nm titanium (Ti) buffer layer on the Si-surfaces. Iron (Fe) and cobalt (Co) were used together to deposite a thickness of 5 nm catalyst layer onto the Single Side Polished (SSP) wafers. As carbon and nitrogen precursor for the CNT growth was used pyridine. Two different treatment times (20 and 60 minutes) in the CVD process determined the CNT forest height. Scanning Electron Microscopy (SEM) imaging was employed to characterize the CNT forest properties and Ag and Au nanoparticle distribution along the CNT walls.

    The existence of “hot spots” created by the Ag and Au nanoparticles through the surface roughness and plasmonic properties was demonstrated by the SERS measurements. Accordingly, the peak intensity at wave number of 1076 cm-1 was picked up from each SERS spectra to establish the Ag- and Au-trend curves with different concentrations of 4-ATP solution. The SERS mapping was also carried out to study the Ag- and Au-coated CNT surface homogeneity and “hot spots” distribution on the CNT surface. The SERS enhancement factors (EF) were calculated by applying an analyte solution of ethanolic 4-ATP on the CNT surface. The calculated values of EF from Ag- and Au-coated CNT forests were 9×106 and 2.7×105 respectively. 

  • 31.
    Alecrim, Viviane
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Zhang, Renyun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Hummelgård, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Andersson, Henrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Andersson, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Olin, Hakan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Photoconductivity of bulk and liquid processed MoS22014Conference paper (Other academic)
  • 32. Alexandrescu, L.
    et al.
    Syverud, K.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Belosi, F.
    Nanofibers against nanoparticles:: Cellulosic nanoparticles for nanoparticle aerosol filtration2012Conference paper (Refereed)
  • 33. Alexandrescu, L.
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Iotti, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    Belosi, F.
    Gatti, A.M.
    Air filtration of nano-particles using cellulose nanofibrils2012Conference paper (Refereed)
  • 34. Alexandrescu, L.
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gatti, A.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cytotoxicity tests of cellulose nanofibril-based structures2013In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20Article in journal (Refereed)
  • 35. Al-Fori, M.
    et al.
    Dobretsov, S.
    Myint, M. T. Z.
    Dutta, Joydeep
    Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, PO Box 17, Postal Code - 123, Al Khoud, Muscat, Oman.
    Antifouling properties of zinc oxide nanorod coatings2014In: Biofouling, ISSN 0892-7014, Vol. 30, no 7, 871-882 p.Article in journal (Refereed)
    Abstract [en]

    In laboratory experiments, the antifouling (AF) properties of zinc oxide (ZnO) nanorod coatings were investigated using the marine bacterium Acinetobacter sp. AZ4C, larvae of the bryozoan Bugula neritina and the microalga Tetraselmis sp. ZnO nanorod coatings were fabricated on microscope glass substrata by a simple hydrothermal technique using two different molar concentrations (5 and 10 mM) of zinc precursors. These coatings were tested for 5 h under artificial sunlight (1060 W m(-2) or 530 W m(-2)) and in the dark (no irradiation). In the presence of light, both the ZnO nanorod coatings significantly reduced the density of Acinetobacter sp. AZ4C and Tetraselmis sp. in comparison to the control (microscope glass substratum without a ZnO coating). High mortality and low settlement of B. neritina larvae was observed on ZnO nanorod coatings subjected to light irradiation. In darkness, neither mortality nor enhanced settlement of larvae was observed. Larvae of B. neritina were not affected by Zn2+ ions. The AF effect of the ZnO nanorod coatings was thus attributed to the reactive oxygen species (ROS) produced by photocatalysis. It was concluded that ZnO nanorod coatings effectively prevented marine micro and macrofouling in static conditions.

  • 36. Al-Hamdi, A. M.
    et al.
    Sillanpää, M.
    Dutta, Joydeep
    Department of Nanotechnology, Water Research Center, Sultan Qaboos University, 123 Al-Khoudh, Musqat, Oman.
    Photocatalytic degradation of phenol in aqueous solution by rare earth-doped SnO2 nanoparticles2014In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, no 14, 5151-5159 p.Article in journal (Refereed)
    Abstract [en]

    The influence of heterogeneous semiconductors on the photodegradation of phenol in water was investigated using doped tin dioxide (SnO2) nanoparticles. Photocatalysts of SnO2 were synthesized with lanthanum (La), cerium (Ce), and neodymium (Nd) dopants. These photocatalysts were synthesized from tin tetrachloride by sol-gel method with different dopant concentrations, and its photocatalytic degradation was investigated up to 0.8 % under UV-A light in aqueous suspensions. The photocatalytic oxidation reactions were studied by varying photocatalyst composition, light intensity, reaction time, pH of the reaction medium, and phenol concentration. It was found that the photocatalytic activity of rare earth-doped SnO2 for phenol decomposition under UV light irradiation was considerably higher than that of pure SnO2 nanoparticles. The experimental results also indicate that more than 95 % phenol was effectively oxidized in the presence of an aqueous suspension of La: SnO2 nanoparticles within 120 min of UV light irradiation.

  • 37. Al-Hamdi, Abdullah M
    et al.
    Sillanpää, Mika
    Dutta, Joydeep
    Water Research Center, Sultan Qaboos University, Oman.
    Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation2015In: Journal of Alloys and Compounds, ISSN 0925-8388, Vol. 618, 366-371 p.Article in journal (Refereed)
    Abstract [en]

    Iodine doped tin oxide (SnO2:I) nanoparticles were prepared by sol-gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO2:I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO2 nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO2 nanoparticles under similar illumination conditions.

  • 38. Al-Hinai, A. T.
    et al.
    Al-Hinai, M. H.
    Dutta, Joydeep
    Sultan Qaboos Univ, Water Res Ctr, Al Khoud 123, Oman.
    Application of Eh-pH diagram for room temperature precipitation of zinc stannate microcubes in an aqueous media2014In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 49, no 1, 645-650 p.Article in journal (Refereed)
    Abstract [en]

    Potential-pH diagram assisted-design for controlled precipitation is an attractive method to obtain engineered binary and ternary oxide particles. Aqueous synthesis conditions of zinc stannate (ZnSnO3) particles at low temperature were formulated with the assistance of potential-pH diagram. The pH of a solution containing stoichiometric amounts of Zn2+ and Sn4+ was controlled for the precipitation in a one pot synthesis step at room temperature (25 degrees C). The effect of the concentration of the reactants on the particle size was studied by varying the concentration of the precursor (Zn2+ + Sn4+) solution. Scanning electron micrographs show that the particles are monodispersed micron sized cubes formed by the self-organization olnano-sized crystallites. The obtained microcubes characterized by X-ray Diffraction and thermo gravimetric analysis (TGA) show that the particles are in ZnSnO3.3H(2)O form.

  • 39. Al-Hinai, M. H.
    et al.
    Al-Hinai, A. T.
    Dutta, Joydeep
    Water Research Center, Sultan Qaboos University, 123 Al Khoud, Oman.
    Phase transformation behavior of zinc metastannates obtained by aqueous precipitation at different temperatures2014In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, no 20, 7282-7289 p.Article in journal (Refereed)
    Abstract [en]

    Phase transformation studies in ZnO-SnO2 system from zinc metastannate (ZnSnO3) to zinc orthostannate (Zn2SnO4) with annealing temperature are reported. Non-centrosymmetric oxides show unique symmetry dependent and spontaneous polarization properties, which are technologically important. ZnSnO3 particles were synthesized by a simple aqueous synthesis at low temperatures designed with the assistance of potential-pH diagrams. ZnSnO3 particles synthesized at 4 A degrees C are more porous losing the ilmenite structure upon annealing at 200 A degrees C, while the other samples prepared at higher temperatures (25-65 A degrees C) becomes amorphous at 300 A degrees C. The phase transformation into the inverse spinel orthostannate phase occurs around 750 A degrees C in all the samples.

  • 40.
    Ali, Hasan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xie, Ling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    van Sebille, Martijn
    Delft University of Technology, Netherlands.
    Fusi, Adele
    Delft University of Technology, Netherlands.
    van Swaaij, Rene A C M M
    Delft University of Technology, Netherlands.
    Zeman, Miro
    Delft University of Technology, Netherlands.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    TEM analysis of multilayered nanostructures formed in the rapid thermal annealed silicon rich silicon oxide film2016In: European Microscopy Congress 2016: Proceedings, 2016, 965-966 p.Conference paper (Other academic)
    Abstract [en]

    Silicon (Si) nanoparticles (NPs) embedded in an ultrathin silicon rich silicon oxide (SRSO) film through the thermal annealing process has emerged as a highly absorbing layer for third-generation solar cells 1. The concept of using Si NPs is to achieve a band gap tunable absorber layer by controlling the size and structure of Si NPs because of the quantum confinement effect 2. In our study, a multilayer stack of silicon oxide with 35 periods of alternating layers of 1-nm thick near-stoichiometric and 3-nm thick Si-rich hydrogenated silicon oxide were deposited on fused quartz substrate by plasma-enhanced chemical vapor deposition (PECVD) method. Two samples were annealed using a rapid thermal annealing (RTA) furnace in forming gas atmosphere (90% N2 + 10% H2) for 210s and 270s respectively. From the Raman spectroscopy, a reduction in crystallinity of Si has been discovered from 210s annealed sample to 270s annealed sample (shown in Figure 2). The goal of transmission electron microscopy (TEM) analysis is to investigate the nanostructural change of Si in these two annealed samples and try to correlate the TEM observations to the Raman spectroscopy results.

    As the dimension of the Si nanostructures formed in SRSO films is in nanometer-scale, the energy-filtered TEM (EFTEM) tomography technique using the low-loss signals in electron energy-loss spectroscopy (EELS) has been applied as a powerful technique to correlate the precipitated Si nanostructures to the phase transformation mechanisms in the thermally annealed SRSO films 3. In this case, EFTEM spectrum-imaging (SI) technique was applied to characterize the Si nanostructures formed in SRSO films by different annealing times. The EFTEM SI dataset was acquired from -4eV to 40eV using a 2eV energy slit and the reconstructed zero loss peak (ZLP) was used to calibrate the spectra shift. Si plasmon images were extracted by fitting a Gaussian into the low-loss region with a peak position at 16.7 eV 4 and FWHM of 4.5 eV. In order to analyze the multilayer structures at different annealing durations, the TEM samples were prepared in cross sectional geometry using the conventional polishing and ion milling methods.

    Figure 1 shows the EFTEM images extracted from the Si plasmon peak, in these images Si appears as bright contrasts. For shorter annealing time, an alternating bright and dark contrast can be observed which indicates that the multilayer structure still remains whereas for longer annealing time, Si shows nanoparticles like contrast. The continuous layer like contrasts shown in Figure 1(a) indicates the overlapping of the contrasts generated by small Si crystallites in a very high density. After longer annealing time (Figure 1(b)), the small Si crystallites grow in size but may take overall less volume fraction due to the Ostwald ripening process. Therefore, it explains the reduction in crystallinity of Si discovered from 210s annealed sample to 270s annealed sample by Raman. However, such a reduction in Si crystallinity was not observed in nitrogen annealed SRSO films, this indicates that samples annealed in the forming gas environment follow a different crystallization mechanism and hydrogen must play a decisive role during the Si crystallization at the initial stage.

  • 41.
    AlMotasem, Ahmed
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Bergström, Jens
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Gåård, Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Holleboom, Thijs
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Adhesion between ferrite iron-€“iron/cementite countersurfaces: A molecular dynamics study2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 103, 113-120 p.Article in journal (Refereed)
    Abstract [en]

    The adhesive properties of Fe(110)/Fe(110) and Fe3C(001)/Fe(110) countersurfaces have been investigated by using classical molecular dynamics simulations. The simulation results show that Fe3C/Fe exhibits a relatively lower adhesion compared to the Fe/Fe. Additionally, the temperature dependence of the adhesive properties between 300–700 K has been examined. The results demonstrate that, with increasing the temperature, the values of the adhesion force and the work of adhesion continuously decrease in the case of Fe3C/Fe; they initially slightly increase up to 500 K then decrease in the case of Fe/Fe. Furthermore, the effect of lattice coherency between Fe/Fe has been examined and found to slightly reduce the adhesion. These results explain how carbides improve galling resistance of tool steel observed during dry sliding. 

  • 42. Al-Naamani, Laila
    et al.
    Dobretsov, Sergey
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Burgess, J. Grant
    Chitosan-zinc oxide nanocomposite coatings for the prevention of marine biofouling2017In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 168, 408-417 p.Article in journal (Refereed)
    Abstract [en]

    Marine biofouling is a worldwide problem affecting maritime industries. Global concerns about the high toxicity of antifouling paints have highlighted the need to develop less toxic antifouling coatings. Chitosan is a natural polymer with antimicrobial, antifungal and antialgal properties that is obtained from partial deacetylation of crustacean waste. In the present study, nanocomposite chitosan-zinc oxide (chitosan-ZnO) nanoparticle hybrid coatings were developed and their antifouling activity was tested. Chitosan-ZnO nanoparticle coatings showed anti-diatom activity against Navicula sp. and antibacterial activity against the marine bacterium Pseudoalteromonas nigrifaciens. Additional antifouling properties of the coatings were investigated in a mesocosm study using tanks containing natural sea water under controlled laboratory conditions. Each week for four weeks, biofilm was removed and analysed by flow cytometry to estimate total bacterial densities on the coated substrates. Chitosan-ZnO hybrid coatings led to better inhibition of bacterial growth in comparison to chitosan coatings alone, as determined by flow cytometry. This study demonstrates the antifouling potential of chitosan-ZnO nanocomposite hybrid coatings, which can be used for the prevention of biofouling. (C) 2016 Elsevier Ltd. All rights reserved.

  • 43. Al-Saadi, Mubarak J.
    et al.
    Al-Harthi, Salim H.
    Kyaw, Htet H.
    Myint, Myo T. Z.
    Bora, Tanujjal
    Laxman, Karthik
    Al-Hinai, Ashraf
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Influence of Atomic Hydrogen, Band Bending, and Defects in the Top Few Nanometers of Hydrothermally Prepared Zinc Oxide Nanorods2017In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 12, 22Article in journal (Refereed)
    Abstract [en]

    We report on the surface, sub-surface (top few nanometers) and bulk properties of hydrothermally grown zinc oxide (ZnO) nanorods (NRs) prior to and after hydrogen treatment. Upon treating with atomic hydrogen (H*), upward and downward band bending is observed depending on the availability of molecular H2O within the structure of the NRs. In the absence of H2O, the H* treatment demonstrated a cleaning effect of the nanorods, leading to a 0.51 eV upward band bending. In addition, enhancement in the intensity of room temperature photoluminescence (PL) signals due to the creation of new surface defects could be observed. The defects enhanced the visible light activity of the ZnO NRs which were subsequently used to photocatalytically degrade aqueous phenol under simulated sunlight. On the contrary, in the presence of H2O, H* treatment created an electronic accumulation layer inducing downward band bending of 0.45 eV (similar to 1/7th of the bulk ZnO band gap) along with the weakening of the defect signals as observed from room temperature photoluminescence spectra. The results suggest a plausible way of tailoring the band bending and defects of the ZnO NRs through control of H2O/H* species.

  • 44. Al-Sabahi, Jamal
    et al.
    Bora, Tanujjal
    Al-Abri, Mohammed
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Controlled defects of zinc oxide nanorods for efficient visible light photocatalytic degradation of phenol2016In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 9, no 4, 238Article in journal (Refereed)
    Abstract [en]

    Environmental pollution from human and industrial activities has received much attention as it adversely affects human health and bio-diversity. In this work we report efficient visible light photocatalytic degradation of phenol using supported zinc oxide (ZnO) nanorods and explore the role of surface defects in ZnO on the visible light photocatalytic activity. ZnO nanorods were synthesized on glass substrates using a microwave-assisted hydrothermal process, while the surface defect states were controlled by annealing the nanorods at various temperatures and were characterized by photoluminescence and X-ray photoelectron spectroscopy. High performance liquid chromatography (HPLC) was used for the evaluation of phenol photocatalytic degradation. ZnO nanorods with high surface defects exhibited maximum visible light photocatalytic activity, showing 50% degradation of 10 ppm phenol aqueous solution within 2.5 h, with a degradation rate almost four times higher than that of nanorods with lower surface defects. The mineralization process of phenol during degradation was also investigated, and it showed the evolution of different photocatalytic byproducts, such as benzoquinone, catechol, resorcinol and carboxylic acids, at different stages. The results from this study suggest that the presence of surface defects in ZnO nanorods is crucial for its efficient visible light photocatalytic activity, which is otherwise only active in the ultraviolet region.

  • 45. Al-Shammari, Rusul M.
    et al.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rice, James H.
    Rodriguez, Brian J.
    Tunable Wettability of Ferroelectric Lithium Niobate Surfaces: The Role of Engineered Microstructure and Tailored Metallic Nanostructures2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 12, 6643-6649 p.Article in journal (Refereed)
    Abstract [en]

    An important aspect of optimizing micro- and optofluidic devices for lab on -a-chip systems is the ability to engineer materials properties including surface structure and charge to control wettability. Biocompatible ferroelectric lithium niobate (LN), which is well-known for acoustic and nonlinear optical applications, has recently found potential micro- and optofluidic applications. However, the tunable wettability of such substrates has yet to be explored in detail. Here, we show that the contact angle of LN substrates can be reproducibly tailored between similar to 7 degrees and similar to 421 degrees by controlling the surface topography and chemistry at the nano- and micrometer scale via ferroelectric domain and polarization engineering and polarization-directed photoassisted deposition of metallic nanostructures.

  • 46.
    Alvebratt, Caroline
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Petersson, E.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Bergström, Christel
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    A small scale method to determine release rate from complexcarrier-mediated systems. 2016In: AAPS Annual Meeting and Exposition. Denver, November 13-17, 2016. / [ed] AAPS, 2016Conference paper (Refereed)
  • 47.
    Alvebratt, Caroline
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Petersson, E.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Bergström, Christel
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Dissolution studies of solid formulations - Applicability of µDiss inmonitoring supersaturation, nucleation and crystallization behavior; Casestudy: Carrier-based formulation.2016In: pION Fiber Optic Advanced Training Course. Uppsala, June 14-15, 2016., 2016Conference paper (Refereed)
  • 48.
    Alvebratt, Caroline
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Petersson, Erik
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Bergström, Christel
    A small scale method to determine release rate from complex carrier-mediated systems2016In: Emerging Technologies in Drug Discovery and Development. Zhuhai, August 23-26, 2016., 2016Conference paper (Refereed)
  • 49.
    Alvebratt, Caroline
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Bergström, Christel
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    A new method that enables in situ measurement of drug release from complex carrier-mediated systems2017In: 6th FIP Pharmaceutical Sciences World Congress2017., 2017Conference paper (Refereed)
  • 50. Amaya, Andrew J.
    et al.
    Pathak, Harshad
    Modak, Viraj P.
    Laksmono, Hartawan
    Loh, N. Duane
    Sellberg, Jonas A.
    Stockholm University, Faculty of Science, Department of Physics. SLAC National Accelerator Laboratory, United States; KTH Royal Institute of Technology, Sweden.
    Sierra, Raymond G.
    McQueen, Trevor A.
    Hayes, Matt J.
    Williams, Garth J.
    Messerschmidt, Marc
    Boutet, Sebastien
    Bogan, Michael J.
    Nilsson, Anders
    Stockholm University, Faculty of Science, Department of Physics. SLAC National Acceleratory Laboratory, United States.
    Stan, Claudiu A.
    Wyslouzil, Barbara E.
    How Cubic Can Ice Be?2017In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 8, no 14, 3216-3222 p.Article in journal (Refereed)
    Abstract [en]

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

1234567 1 - 50 of 1912
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf