Sri Lanka Institute of Nanotechnology SLINTEC

Walgama, Sri Lanka

Sri Lanka Institute of Nanotechnology SLINTEC

Walgama, Sri Lanka

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Koneswaran M.,Sri Lanka Institute of Nanotechnology SLINTEC | Koneswaran M.,University of Manchester | Narayanaswamy R.,University of Manchester
Microchimica Acta | Year: 2012

We have synthesised water soluble CdS/ZnS core-shell quantum dots (QDs) capped with mercaptoacetic acid (MAA). They were characterised by UV-vis absorption spectroscopy, fluorescence spectroscopy, FT-IR and transmission electron microscopy. Such QDs can be used as fluorescent probes for the determination of metal ions because they quench the fluorescence of the QDs. The QDs exhibit absorption and emission bands at 345 nm and 475 nm respectively, which is more longer wavelength compared to MAA-capped CdS QDs and obviously is the result of the larger particle size. The fluorescence intensity of CdS-based QDs is strongly enhanced by coating them with a shell of ZnS. In addition, such functionalised QDs are more sensitive to Hg(II) ions. Parameters such as pH, temperature and concentration of the QDs have been optimised. A high selectivity and sensitivity toward Hg(II) ions is obtained at pH 7. 4 and a concentration of 12. 0 mg of QDs per L. Under optimum conditions, the fluorescence intensity of CdS/ZnS QDs is linearly proportional to the concentration of Hg(II) in the range from 2. 5 to 280 nM, with a detection limit of 2. 2 nM. The effect of potentially interfering cations was examined and confirmed the high selectivity of this material. © 2012 Springer-Verlag.


Hiralal P.,Nokia Inc. | Hiralal P.,University of Cambridge | Unalan H.E.,Middle East Technical University | Amaratunga G.A.J.,University of Cambridge | Amaratunga G.A.J.,Sri Lanka Institute of Nanotechnology SLINTEC
Nanotechnology | Year: 2012

As a result of their morphology, nanowires bring new properties and the promise of performance for a range of electronic devices. This review looks into the properties of nanowires and the multiple ways in which they have been exploited for energy generation, from photovoltaics to piezoelectric generators. © 2012 IOP Publishing Ltd.


Tissera N.D.,Sri Lanka Institute of Nanotechnology SLINTEC | Wijesena R.N.,Sri Lanka Institute of Nanotechnology SLINTEC | De Silva K.M.N.,Sri Lanka Institute of Nanotechnology SLINTEC | De Silva K.M.N.,University of Colombo
Ultrasonics Sonochemistry | Year: 2016

Acoustic cavitation formed due to propagation of ultrasound wave inside a dye bath was successfully used to dye cotton fabric with a reactive dye at lower temperatures. The energy input to the system during sonication was 0.7 W/cm2. This was within the energy range that contributes towards forming cavitation during ultra-sonication. The influence of ultrasound treatment on dye particle size and fiber morphology is discussed. Particle size analysis of the dye bath revealed ultra-sonication energy was capable of de-agglomeration of hydrolyzed dye molecules during dyeing. SEM micrograph and AFM topographical image of the fiber surface revealed fiber morphology remains unchanged after the sonication. The study was extended in understanding the contribution of ultrasound method of dyeing towards achieving good color strength on the fabric, compared to the normal heating method of dyeing. Study showed color strength obtained using ultra sound method of dyeing is higher compared to normal heating dyeing. Ultrasound energy was able to achieve the good color strength on cotton fabric at very low temperature such as 30 °C, which was approximately 230% more than the color strength achieved in normal heating method of dyeing. This indicates that energy input to the system using ultrasound was capable of acting as an effective alternative method of dyeing knitted cotton fabrics with reactive dye. © 2015 Elsevier B.V. All rights reserved.


Haworth B.,Loughborough University | Ratnayake U.N.,Sri Lanka Institute of Nanotechnology SLINTEC
International Polymer Processing | Year: 2011

Layered structures in inorganic minerals are not easily intercalated when combined with conventional non-polar polymers such as polypropylene (PP). A new co-intercalation method is reported whereby the combined influence of low molecular weight polar additives and polyolefin-based compatibilizers on PP-clay nanocomposites (PPCN) has been investigated. Our research has shown that the interlayer spacing of montmorillonite clay increases dramatically, and increased particle dispersion is achieved, when short chain, organic additives (typically amidetype, AM) are included. In this work, the migration of these additives into the clay galleries has been confirmed by surface energy data (from contact angle experiments) and by various capillary flow measurement techniques. Shear flow data have been used to interpret the mechanism of intercalation, following compound preparation using melt-state mixing processes. At relatively low concentrations, the erucamide molecules assist the intercalation process in nanocomposites; however if an excess of AM is apparent within the bulk polymer melt, unusual flow behavior is observed which can be attributed to wall slip. Modified melt elasticity is also obtained with the PPCN's leading to reduced die swell characteristics in extrusion processes. Significant differences in melt flow behavior can therefore be attributed to the presence of AM; a mechanism for co-intercalation has been proposed in terms of hydrogen bonding between the additives and the silicate layers. © Carl Hanser Verlag GmbH & Co. KG.


Butt H.,University of Cambridge | Dai Q.,University of Cambridge | Rajesekharan R.,University of Cambridge | Wilkinson T.D.,University of Cambridge | And 2 more authors.
ACS Nano | Year: 2011

Highly dense periodic arrays of multiwalled carbon nanotubes behave like low-density plasma of very heavy charged particles, acting as metamaterials. These arrays with nanoscale lattice constants can be designed to display extended plasmonic band gaps within the optical regime, encompassing the crucial optical windows (850 and 1550 nm) simultaneously. We demonstrate an interesting metamaterial waveguide effect displayed by these nanotube arrays containing line defects. The nanotube arrays with lattice constants of 400 nm and radius of 50 nm were studied. Reflection experiments conducted on the nanoscale structures were in agreement with numerical calculations. © 2011 American Chemical Society.


Butt H.,University of Cambridge | Rajesekharan R.,University of Melbourne | Dai Q.,University of Cambridge | Sarfraz S.,University of Cambridge | And 4 more authors.
Applied Physics Letters | Year: 2012

The forests of carbon nanotubes have been termed as the darkest man-made materials. Such materials exhibit near-perfect optical absorption (reflectance∼0.045%) due to low reflectance and nanoscale surface roughness. We have demonstrated the utilization of these perfectly absorbing forests to produce binary amplitude cylindrical Fresnel lenses. The opaque Fresnel zones are defined by the dark nanotube forests and these lenses display efficient focusing performance at optical wavelengths. Lensing performance was analyzed both computationally and experimentally with good agreement. Such nanostructure based lenses have many potential applications in devices like photovoltaic solar cells. © 2012 American Institute of Physics.


Butt H.,University of Cambridge | Butler T.,University of Cambridge | Montelongo Y.,University of Cambridge | Rajesekharan R.,University of Melbourne | And 3 more authors.
Applied Physics Letters | Year: 2012

We report the remarkable diffraction effects produced from circular patterned arrays of multiwalled carbon nanotubes (MWCNTs). Highly ordered circular arrays of multiwalled carbon nanotubes (with inter-nanotube spacings of 633 nm) display optical dispersion effects similar to compact discs. These arrays display remarkable diffraction patterns in the far field which are spatially continuous. High quality diffraction patterns were obtained experimentally which are in excellent agreement with the theoretical calculations. The achieved continuous diffraction patterns pave the way towards the utilization of engineered carbon nanotube arrays in applications like three dimensional holograms. © 2012 American Institute of Physics.


Dai Q.,University of Cambridge | Dai Q.,CAS National Center for Nanoscience and Technology | Rajasekharan R.,University of Cambridge | Butt H.,University of Cambridge | And 4 more authors.
Small | Year: 2012

An ultrasmall tunable microlens with a diameter of 1.5 μm is fabricated using nematic liquid crystals (electrically tunable medium) and vertically aligned carbon nanofibers (CNFs, electrodes). Individual CNFs are grown at the center of circular dielectric regions. This allows the CNFs to produce a more Gaussian electric field profile and hence more uniformity in lens array switching. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Rajasekharan R.,University of Cambridge | Butt H.,University of Cambridge | Dai Q.,University of Cambridge | Wilkinson T.D.,University of Cambridge | And 2 more authors.
Advanced Materials | Year: 2012

Reflective binary Fresnel lenses fabricated so far all suffer from reflections from the opaque zones and hence degradation in focusing and lensing properties. Here a solution is found to this problem by developing a carbon nanotube Fresnel lens, where the darkest man-made material ever, i.e., low-density vertically aligned carbon nanotube arrays, are exploited. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Butt H.,University of Cambridge | Montelongo Y.,University of Cambridge | Butler T.,University of Cambridge | Rajesekharan R.,University of Melbourne | And 5 more authors.
Advanced Materials | Year: 2012

Carbon nanotubes are used as the smallest possible scattering element for diffracting light in a highly controlled manner to produce a 2D image. An array of carbon nanotubes is elegantly patterned to produce a high resolution hologram. In response to incident light on the hologram, a high contrast and wide field of view CAMBRIDGE image is produced. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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