| 1. |
- Bender, P., et al.
(författare)
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Structural and magnetic properties of multi-core nanoparticles analysed using a generalised numerical inversion method
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- The structural and magnetic properties of magnetic multi-core particles were determined by numerical inversion of small angle scattering and isothermal magnetisation data. The investigated particles consist of iron oxide nanoparticle cores (9 nm) embedded in poly(styrene) spheres (160 nm). A thorough physical characterisation of the particles included transmission electron microscopy, X-ray diffraction and asymmetrical flow field-flow fractionation. Their structure was ultimately disclosed by an indirect Fourier transform of static light scattering, small angle X-ray scattering and small angle neutron scattering data of the colloidal dispersion. The extracted pair distance distribution functions clearly indicated that the cores were mostly accumulated in the outer surface layers of the poly(styrene) spheres. To investigate the magnetic properties, the isothermal magnetisation curves of the multicore particles (immobilised and dispersed in water) were analysed. The study stands out by applying the same numerical approach to extract the apparent moment distributions of the particles as for the indirect Fourier transform. It could be shown that the main peak of the apparent moment distributions correlated to the expected intrinsic moment distribution of the cores. Additional peaks were observed which signaled deviations of the isothermal magnetisation behavior from the non-interacting case, indicating weak dipolar interactions.
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| 2. |
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| 3. |
- Wang, Q., et al.
(författare)
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Compacted nanoscale sensors by merging ZnO nanorods with interdigitated electrodes
- 2011
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Ingår i: Proc SPIE Int Soc Opt Eng. - : SPIE. - 9780819486059
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Konferensbidrag (refereegranskat)abstract
- ZnO nanorods (NRs) sensors utilizing hybrid or monolithic integration of the NRs on nanoscale or microscale interdigitated electrodes (IDEs) were fabricated and characterized. The IDEs with their finger electrode width ranging from 50 nm to 3 μm were formed on SiO2/Si substrates by nanoimprint lithography or conventional photolithography and metallization techniques, whereas the ZnO NRs were grown by chemical synthesis method. The average diameter of the ZnO NRs is about 100 nm, and their length can be varied from 2 to 5 μm by controlling growth time. When sensing targets, such as molecules or nanoparticles, bind onto the ZnO NRs, the conductance between IDEs will change. As probing test, II-VI quantum dots (QDs) were attached on the ZnO NRs, and clear responses were obtained by measuring and comparing current-voltage (I-V) characteristic of the sensor before and after binding the QDs.
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| 4. |
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| 5. |
- Dutta, Joydeep, 1964-, et al.
(författare)
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Colloidal self-organization for nanoelectronics
- 2004
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Ingår i: Proceedings ICSE 2004. - : IEEE. - 0780386582 - 9780780386587 ; , s. 146-148
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Konferensbidrag (refereegranskat)abstract
- The major part of the expenses in modern IC manufacturing process is nowadays devoted to the R&D needed to optimize chip size, wafer size, defecrivity and interconnects- building up to keep Moore's law a reality. But the question is: Can circuits with sub-0.1μm dimensions be fabricated by the extension of current device production technologies? An interdisciplinary 'off the beaten path' approach is mandatory to overcome future limitations. One such approach is fabrication of devices (or at least parts of devices) by self-organization.
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| 6. |
- Lobov, G. S., et al.
(författare)
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Direct birefringence and transmission modulation via dynamic alignment of P3HT nanofibers in an advanced opto-fluidic component
- 2017
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Ingår i: Optical Materials Express. - 2159-3930 .- 2159-3930. ; 7:1, s. 52-61
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Tidskriftsartikel (refereegranskat)abstract
- Poly-3-hexylthiophene (P3HT) nanofibers are semiconducting high-aspect ratio nanostructures with anisotropic absorption and birefringence properties found at different regions of the optical spectrum. In addition, P3HT nanofibers possess an ability to be aligned by an external electric field, while being dispersed in a liquid. In this manuscript we show that such collective ordering of nanofibers, similar to liquid crystal material, significantly changes the properties of transmitted light. With a specially fabricated opto-fluidic component, we monitored the phase and transmission modulation of light propagating through the solution of P3HT nanofibers, being placed in the electric field with strength up to 0.1 V/μm. This report describes a technique for light modulation, which can be implemented in optical fiber-based devices or on-chip integrated components.
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| 7. |
- Lobov, Gleb S., et al.
(författare)
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Electro-optical response of P3HT nanofibers in liquid solution
- 2015
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Ingår i: Asia Communications and Photonics Conference, ACPC 2015. - Washington, D.C. : OSA. - 9781943580064
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Konferensbidrag (refereegranskat)abstract
- AC electric poling introduces in P3HT nanofibers anisotropic electro-optical response and birefringence. Along with birefringence, such material exhibits strong amplitude modulation which makes it more efficient alternative to liquid crystals.
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| 8. |
- Majee, Subimal, 1984-, et al.
(författare)
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Highly Conductive Films by Rapid Photonic Annealing of Inkjet Printable Starch–Graphene Ink
- 2021
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Ingår i: Advanced Materials Interfaces. - : John Wiley and Sons Inc. - 2196-7350. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- A general formulation engineering method is adopted in this study to produce a highly concentrated (≈3 mg mL−1) inkjet printable starch–graphene ink in aqueous media. Photonic annealing of the starch–graphene ink is validated for rapid post-processing of printed films. The experimental results demonstrate the role of starch as dispersing agent for graphene in water and photonic pulse energy in enhancing the electrical properties of the printed graphene patterns, thus leading to an electrical conductivity of ≈2.4 × 104 S m−1. The curing mechanism is discussed based on systematic material studies. The eco-friendly and cost-efficient approach presented in this work is of technical potential for the scalable production and integration of conductive graphene inks for widespread applications in printed and flexible electronics.
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| 9. |
- Sugunan, A, et al.
(författare)
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Heavy-metal ion sensors using chitosan-capped gold nanoparticles
- 2005
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Ingår i: Science and Technology of Advanced Materials. - : Informa UK Limited. - 1468-6996 .- 1878-5514. ; 6:3-4, s. 335-340
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Tidskriftsartikel (refereegranskat)abstract
- We report a novel strategy for using gold nanoparticles capped with chitosan for sensing ions of heavy metals. Acidic anions (glutamate ions in our case) are expected to cap the nanoparticle surfaces similar to conventional methods of stabilization of gold nanoparticles by citrate ions. The polycationic nature of chitosan enables attachment of the polymer to the negatively charged gold nanoparticle surfaces through electrostatic interactions. Use of chitosan serves dual purpose of providing sufficient steric hindrance ensuring stability of the colloid and also to functionalize the nanoparticles for use as sensors. The well-documented chelating properties of chitosan and the sensitivity of the optical properties of gold nanoparticles to agglomeration have been employed to detect low concentrations of heavy metals ions (Zn2+ and Cu2+) in water. A comparison of the optical absorption spectra of the colloidal suspension before and after exposure to metal ions is a good indicator of the concentration of the heavy metal ions.
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| 10. |
- Zhao, Wei
(författare)
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Aqueous graphene dispersions for paper packaging
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Graphene is widely touted as the thinnest and the most versatile material available. As an atomically thin layer of carbon atoms arranged in a hexagonal configuration, graphene has a combination of technologically important properties, such as thermal and electrical conductivity, mechanical strength, and impermeability to gases. From an industrial perspective on applications, water as a dispersing media for graphene offers safer handling and environmental benefits compared with conventional organic solvents. However, the high surface tension of water and the attractive forces between graphene surfaces drive the sheets to aggregation. Although surfactants have been an important stepping stone in the advancement of aqueous graphene dispersions, these surface-active molecules are often needed in excess and have adverse effects on coatings during film formation. These challenges limit the industrial relevance of graphene as an effective barrier in composites. In general, gas barriers against both oxygen and water vapour, made from a single coating formulation, is seemingly a holy grail for the packaging industry. In this thesis work, the aim was to gain a fundamental understanding of aqueous graphene dispersions for gas barriers used in paper packaging. Biobased materials were systematically investigated as dispersing agents for graphene based on dispersing conditions and functional barrier performance. Flavin mononucleotide (FMN), a food additive, dispersed graphene using a relatively low amount of FMN and showed intriguing spectroscopic signatures of π-π interactions with graphene. Starch nanoparticles (SNPs) realised concentrated and stable aqueous graphene dispersions for composite films. The SNP-stabilized graphene sheets in starch films lowered the gas permeability of both oxygen and water vapour simultaneously by over 70% under all the conditions tested. In general, a combined gas barrier performance is unusual for both bioplastics and common petrochemical-based plastics used in the packaging industry. Motivated by the graphene network leading to the extraordinary barrier performance, the aqueous SNP-graphene dispersion was modified for inkjet printing. The printed patterns were flexible and electrically conductive in the order of 104 S m-1 that is on par with the highest reported values in the literature. These surfactant-free aqueous SNP-graphene dispersions have the potential and versatility for paper-based gas barriers with integrated electronics. Multifunctional composite films made from these dispersions, when optimized, could become competitive with commercial plastics, and meet the current and future demands of the packaging industry.
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