| 1. |
- Gustafsson, Oscar, et al.
(författare)
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Long-wavelength infrared quantum-dot based interband photodetectors
- 2011
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Ingår i: Infrared physics & technology. - : Elsevier BV. - 1350-4495 .- 1879-0275. ; 54:3, s. 287-291
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Tidskriftsartikel (refereegranskat)abstract
- We report on the design and fabrication of (Al)GaAs(Sb)/InAs tensile strained quantum-dot (QD) based detector material for thermal infrared imaging applications in the long-wavelength infrared (LWIR) regime. The detection is based on transitions between confined dot states and continuum states in a type-II band lineup, and we therefore refer to it as a dot-to-bulk (D2B) infrared photodetector with expected benefits including long carrier lifetime due to the type-II band alignment, suppressed Shockley-Read-Hall generation-recombination due to the relatively large-bandgap matrix material, inhibited Auger recombination processes due to the tensile strain and epitaxial simplicity. Metal-organic vapor-phase epitaxy was used to grow multiple (Al)GaAs(Sb) QD layers on InAs substrates at different QD nominal thicknesses, compositions, doping conditions and multilayer periods, and the material was characterized using atomic force and transmission electron microscopy, and Fourier-transform infrared absorption spectroscopy. Dot densities up to 1 x 10(11) cm(-2), 1 x 10(12) cm(-2) and 3 x 10(10) cm(-2) were measured for GaAs, AlGaAs and GaAsSb QDs, respectively. Strong absorption in GaAs, AlGaAs and GaAsSb multilayer QD samples was observed in the wavelength range 6-12 mu m. From the wavelength shift in the spectral absorption for samples with varying QD thickness and composition it is believed that the absorption is due to an intra- valance band transition. From this it is possible to estimate the type-II inter-band transition wavelength, thereby suggesting that (Al)GaAs(Sb) QD/InAs heterostructures are suitable candidates for LWIR detection and imaging.
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| 2. |
- Afif, A., et al.
(författare)
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Electrochemical and structural characterization of BaCe 0.7 Zr 0.15 Y 0.1 Zn 0.05 O 3-δ as an electrolyte for SOFC-H
- 2018
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Ingår i: IET Conference Publications. ; 2018:CP750
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Konferensbidrag (refereegranskat)abstract
- As a potential electrolyte for proton-conducting solid oxide fuel cells (SOFC-Hs) and to get better protonic conductivity and stability, zinc doped BCZY material has been found to be promising. In this study, we report a new composition of proton conductors BaCe0.7Zr0.15Y01Zn0.05O3-s (BCZYZn10) which was investigated using XRD, SEM and conductivity measurements. Rietveld refinement of the XRD data revel a cubic perovskite structure with Pm-3m space group. Rietveld analysis of BaCe07Zr0.15Y01Zn0.05O3-5 shows the unit cell parameter is a = 4.3582(7) A. Scanning electron microscopy images shows that the grain sizes are large and compact which gives the sample high density and good protonic conductivity. The total conductivity in wet atmosphere is significantly higher than that of dry condition and the conductivity was found to be 0.004032 Scm-1 and 0.00164 Scm-1 at 600 °C in wet and dry Ar, respectively. This study indicated that perovskite electrolyte BCZYZn10 is a promising material for the next generation intermediate temperature solid oxide fuel cells (IT-SOFCs).
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| 3. |
- Khan, MD S. A., et al.
(författare)
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Energy Harvesting- A Technical Analysis of Evolution, Control Strategies and Future Aspects
- 2019
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Ingår i: Journal of Electronic Science and Technology. - 1674-862X. ; 17:2, s. 116-125
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Tidskriftsartikel (refereegranskat)abstract
- This paper provides a tech nical analysisof energy harvesting, including different aspects ofharvesting energy, individual case history, controlstrategies of harvesting in each energy sector togetherwith the current trend and future aspects of it. Energyharvesting is comparativ ely a new concept which isgrowing very fast since the 20th century and catchingn ew generation research approach . The paper not onlydescribes the past and current scenarios of harvestingenergy with radio frequency and renewables but alsogives author’s own anticipation of the upcoming futuretrends of it comparing the case histories .
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| 4. |
- Mautner, Andreas, et al.
(författare)
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Phosphorylated nanocellulose papers for copper adsorption from aqueous solutions
- 2016
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Ingår i: International Journal of Environmental Science and Technology. - : Springer Science and Business Media LLC. - 1735-1472 .- 1735-2630. ; 13:8, s. 1861-1872
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Tidskriftsartikel (refereegranskat)abstract
- Copper is a major problem in industrial wastewater streams, seriously affecting the quality of potential drinking water. Several approaches, including continuous membrane processes or batch-wise application of adsorbents, are in use to tackle this problem. Unfortunately, these processes suffer from their particular drawbacks, such as low permeance or disposal of saturated adsorbents. However, a combination of these processes could constitute a step towards a more efficient copper removal solution. Here, we present a nanopaper ion-exchanger prepared from cellulose nanofibrils produced from fibre sludge, a paper industry waste stream, for the efficient, continuous removal of copper from aqueous solutions. This nanopaper ion-exchanger comprises phosphorylated cellulose nanofibrils that were processed into nanopapers by papermaking. The performance of these phosphorylated nanopaper membranes was determined with respect to their rejection of copper and permeance. It was shown that this new type of nanopaper is capable of rejecting copper ions during a filtration process by adsorption. Results suggest that functional groups on the surface of the nanopapers contribute to the adsorption of copper ions to a greater extent than phosphate groups within the bulk of the nanopaper. Moreover, we demonstrated that those nanopaper ion-exchangers could be regenerated and reused and that in the presence of calcium ions, the adsorption capacity for copper was only slightly reduced
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| 5. |
- Afroze, Shammya, et al.
(författare)
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Latest development of double perovskite electrode materials for solid oxide fuel cells: a review
- 2019
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Ingår i: Frontiers in Energy. - : Springer Science and Business Media LLC. - 2095-1698 .- 2095-1701. ; 13:4, s. 770-797
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Forskningsöversikt (refereegranskat)abstract
- Recently, the development and fabrication of electrode component of the solid oxide fuel cell (SOFC) have gained a significant importance, especially after the advent of electrode supported SOFCs. The function of the electrode involves the facilitation of fuel gas diffusion, oxidation of the fuel, transport of electrons, and transport of the byproduct of the electrochemical reaction. Impressive progress has been made in the development of alternative electrode materials with mixed conducting properties and a few of the other composite cermets. During the operation of a SOFC, it is necessary to avoid carburization and sulfidation problems. The present review focuses on the various aspects pertaining to a potential electrode material, the double perovskite, as an anode and cathode in the SOFC. More than 150 SOFCs electrode compositions which had been investigated in the literature have been analyzed. An evaluation has been performed in terms of phase, structure, diffraction pattern, electrical conductivity, and power density. Various methods adopted to determine the quality of electrode component have been provided in detail. This review comprises the literature values to suggest possible direction for future research.
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| 6. |
- Abdel-Karim, R., et al.
(författare)
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Electrodeposition and Characterization of Nanocrystalline Ni-Fe Alloys
- 2011
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Ingår i: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4110 .- 1687-4129. ; , s. 519274-
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- Karim, Zoheb, et al.
(författare)
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Forming a cellulose based nanopaper using XPM
- 2017
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Ingår i: International Conference on Nanotechnology for Renewable Materials 2017. - : TAPPI Press. - 9781510850897 ; , s. 399-407
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Konferensbidrag (refereegranskat)
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| 8. |
- Radiom, Soheil, et al.
(författare)
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Far-Field On-Chip Antennas Monolithically Integrated in a Wireless-Powered 5.8-GHz Downlink/UWB Uplink RFID Tag in 0.18-mu m Standard CMOS
- 2010
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Ingår i: IEEE Journal of Solid-State Circuits. - 0018-9200 .- 1558-173X. ; 45:9, s. 1746-1758
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses two antennas monolithically integrated on-chip to be used respectively for wireless powering and UWB transmission of a tag designed and fabricated in 0.18-mu m CMOS technology. A multiturn loop-dipole structure with inductive and resistive stubs is chosen for both antennas. Using these on-chip antennas, the chip employs asymmetric communication links: at downlink, the tag captures the required supply wirelessly from the received RF signal transmitted by a reader and, for the uplink, ultra-wideband impulse-radio (UWB-IR), in the 3.1-10.6-GHz band, is employed instead of backscattering to achieve extremely low power and a high data rate up to 1 Mb/s. At downlink with the on-chip power-scavenging antenna and power-management unit circuitry properly designed, 7.5-cm powering distance has been achieved, which is a huge improvement in terms of operation distance compared with other reported tags with on-chip antenna. Also, 7-cm operating distance is achieved with the implemented on-chip UWB antenna. The tag can be powered up at all the three ISM bands of 915 MHz and 2.45 GHz, with off-chip antennas, and 5.8 GHz with the integrated on-chip antenna. The tag receives its clock and the commands wirelessly through the modulated RF powering-up signal. Measurement results show that the tag can operate up to 1 Mb/s data rate with a minimum input power of -19.41 dBm at 915-MHz band, corresponding to 15.7 m of operation range with an off-chip 0-dB gain antenna. This is a great improvement compared with conventional passive RFIDs in term of data rate and operation distance. The power consumption of the chip is measured to be just 16.6 mu W at the clock frequency of 10 MHz at 1.2-V supply. In addition, in this paper, for the first time, the radiation pattern of an on-chip antenna at such a frequency is measured. The measurement shows that the antenna has an almost omnidirectional radiation pattern so that the chip's performance is less direction-dependent.
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| 9. |
- Castro, Daniele Oliveira, et al.
(författare)
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The use of a pilot-scale continuous paper process for fire retardant cellulose-kaolinite nanocomposites
- 2018
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Ingår i: Composites Science And Technology. - : Elsevier Ltd. - 0266-3538 .- 1879-1050. ; 162, s. 215-224
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured materials are difficult to prepare rapidly and at large scale. Melt-processed polymer-clay nanocomposites are an exception, but the clay content is typically below 5 wt%. An approach for manufacturing of microfibrillated cellulose (MFC)/kaolinite nanocomposites is here demonstrated in pilot-scale by continuous production of hybrid nanopaper structures with thickness of around 100 μm. The colloidal nature of MFC suspensions disintegrated from chemical wood fiber pulp offers the possibility to add kaolinite clay platelet particles of nanoscale thickness. For initial lab scale optimization purposes, nanocomposite processing (dewatering, small particle retention etc) and characterization (mechanical properties, density etc) were investigated using a sheet former (Rapid Köthen). This was followed by a continuous fabrication of composite paper structures using a pilot-scale web former. Nanocomposite morphology was assessed by scanning electron microscopy (SEM). Mechanical properties were measured in uniaxial tension. The fire retardancy was evaluated by cone calorimetry. Inorganic hybrid composites with high content of in-plane oriented nanocellulose, nanoclay and wood fibers were successfully produced at pilot scale. Potential applications include fire retardant paperboard for semi structural applications and as reinforcement mats in molded thermoset biocomposites.
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| 10. |
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