By Topic

Micro & Nano Letters, IET

Issue 4 • Date April 2011

Filter Results

Displaying Results 1 - 25 of 26
  • Preparation and characterisation of PLGA microspheres for sustained release of recombinant human granulocyte colony-stimulating factor

    Page(s): 181 - 185
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (314 KB)  

    The purpose of this research was to develop a sustained micosphere for recombinant human granulocyte colony-stimulating factor (RHG-CSF). RHG-CSF was first incorporated into glassy sodium hyaluronate (HA) particle according to the freezing-induced phase separation method previously reported by the authors' group. Once G-CSF was incorporated in the glassy HA particles, it gained resistance to organic solvents. The glassy HA particle containing G-CSF was subsequently encapsulated into polylactic-co-glycolic acid (PLGA) matrix to get HA-PLGA composite microspheres by the solid-in-oil-in-water multiple emulsion technique. The novel glassy HA particle and composite microsphere were characterised by scanning electron microscopy, particle and size distribution, size-exclusion HPLC. The in vitro release data indicate that continuous and sustained release profile was achieved for more than 30 days compared with microspheres prepared by the traditional water-in-oil-in-water method. Also the bioassay was assessed by proliferative ability of NSF-60 cell line and the result suggests that the bioactivity was preserved well in the process of formulation steps and in vitro release. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Deposition of gold nanoparticles onto poly (DL-lactic acid) microbubbles using cetyltriethylammnonium bromide as a surface modification agent

    Page(s): 186 - 189
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (267 KB)  

    A simple method for preparing organic-inorganic composite particles based on poly (DL-lactic acid) (PLA) microbubbles and gold nanoparticles is presented in this study. PLA microbubbles are first prepared using a double emulsion-solvent evapouration technique. The surfaces of the prepared PLA microbubbles are modified by a cationic surface active agent, cetyltrimethylammonium bromide, which provides a positively charged outer surface. Negatively charged gold nanoparticles are synthesised and deposited on the surfaces of the modified PLA microbubbles through an interaction of electrostatic attraction to prepare gold nanoparticles and PLA microbubbles composite particles. The composite particles are characterised by electron microscopy, UV-vis spectroscopy, X-ray diffraction and X-ray photoelectron spectroscope. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Structural transformation and electrochemical characterisation of cobalt hydroxide carbonate nanostructures

    Page(s): 190 - 195
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (402 KB)  

    Cobalt hydroxide is considered one of the promising materials for the fabrication of various electrodes and electrochemical devices. However, detailed information on the structural transformation of cobalt hydroxide remains scarce. In this study, cobalt hydroxide intercalated with carbonate anions was synthesised in different phase structures and morphologies, including non-crystal nanosheets and single-crystal nanorods and nanosheets, using amino acid (glycine) molecules. The transformation of phases and morphologies was time dependent and directed by glycine molecules, accompanied by the formation of rodlike-embryo intermediates. The samples were characterised by X-ray diffraction, transmission electron microscopy and high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. Furthermore, the electrochemical property of cobalt hydroxide carbonate nanostructures was characterised by cyclic voltammetry measurement, suggesting their preferential application as supercapacitor materials. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Controlled synthesis of basic bismuth nitrate by reverse microemulsion

    Page(s): 196 - 200
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    Basic bismuth nitrate (BBN) with different shapes and dimensionalities were controllably synthesised in reverse microemulsion stabilised by TritonX-100. The obtained products were characterised by thermogravimetry differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD and TG-DSC detections revealed that the as-prepared BBN had the composition Bi6O6(OH)2(NO3)4·2H2O. The TEM results indicated that 1D nanorods, 2D hexagonal nanoplates and irregular nanosheets of BBN were obtained by changing the water content (w, molar ratio of water to surfactant). At low w, most of the products were nanorods with 100-200 nm in diameter and 3-7 μm in length. Hexagonal nanoplates with the side length of 250-350 nm were formed at higher w. When w further increased to 10, irregular nanosheets with 2-8 μm in size were found. The morphology of products was also sensitive to the surfactant concentration and reaction time. It was found that the growth of BBN nanoplates is a function of time. The possible formation mechanism of these nanostructures was also discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Handheld device for the enrichment of rare cells utilising dielectrophoresis in stepping electric fields

    Page(s): 201 - 204
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (652 KB)  

    The ability to enrich rare cells, for example, circulating tumour cells, circulating foetal cells and stem cells, has been an important issue in medical diagnostics and characterisation. The main purpose of this investigation was to develop a handheld microdevice capable of the effective preconcentration of rare cells. Circular microelectrodes were designed to generate the stepping electric field by switching the electric field to an adjacent electrode pair by relays. The cancerous cells with positive dielectrophoretic response were not only conveyed but also concentrated towards the centre of the circular microelectrodes because the high-electric-field region between the adjacent electrodes was gradually decreased in the direction of the stepping electric field. Numerical simulations of the electric fields were performed to demonstrate the concept of the proposed design. Moreover, enrichment of cervical cancer cells was successfully achieved and took about 160 s in the experiment with an approximate efficiency of 75 , when the peak-to-peak voltage of 16 V, a frequency of 600 kHz and the time interval of relay switching with 20 s were applied. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Chemical synthesis of SrCO3 microcrystals via a homogeneous precipitation method

    Page(s): 205 - 208
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    Strontium carbonates (SrCO3) microcrystals have been synthesised through a modified homogeneous precipitation method, in which urea plays an important role. Compared to the direct precipitation approach, the present homogeneous precipitation method tends to provide an appropriate chemical microenvironment for the formation of rod-like SrCO3 microcrystals. Flower-like SrCO3 microcrystals can be formed by adding sodium dodecyl sulphate under the experimental condition. Powder X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectrometry are used to characterise various properties of the as-prepared samples. This approach provides a facile route for the preparation of SrCO3 microcrystals, which may be applicable to the synthesis of other carbonates. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Gold/hydroxypropyl cellulose hybrid nanocomposite constructed with more complete coverage of gold nano-shell

    Page(s): 209 - 213
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    The gold nanocomposite supported on hydroxypropyl cellulose (HPC) using NaBH4 as a medium has been prepared successfully here. A brownish-red solution in its UV-vis absorption spectrum showed surface plasmon resonance absorption bands between 520 and 560-nm in solutions. The Au/HPC nanocomposite was characterised by X-ray diffraction (XRD) measurement, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). XRD showed the fcc crystal structure of the bulk Au with particles of less than 22-nm in size similar to that is observed by TEM and HPC is crucial for the formation of such gold nanocomposite. SEM indicated uniform distribution of particles in the film. TGA confirmed enhanced thermal stability of the polymer. This easy synthetic approach to gold nano- and microstructures is a seedless, one-step, fast, template-free route that shows good reproducibility and may be further developed to produce other types of metal nanostructures that satisfy specific applications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Contact nanomechanics of a capped nanotube indented on graphite and diamond surfaces

    Page(s): 214 - 216
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    Contact behaviour of a capped single-walled carbon nanotube (SWCNT) indented into the surface of graphite sheets and diamond is studied using molecular dynamics simulation. The interactions between SWCNT, graphite and diamond atoms are described by the Tersoff-Brenner potential, and the Lennard-Jones potential function is employed to simulate the interactions between the indenter and the graphite and diamond atoms. The simulation results show that the maximum contact force increases with increasing indentation velocity and with decreasing indentation temperature. In addition, the diamond appears a greater force exerted on the indenter than the graphite sheets. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Synthesis of a new dithiocarbamate cobalt complex and its nanoparticles with the study of their biological properties

    Page(s): 217 - 220
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    Nanodithiocarbamate (DTC) complexes have been prepared by the reaction between DTC and metal salt under ultrasound irradiation. The DTC complex nanoparticles have been prepared in water. The antimicrobial activity of nanoparticles derivatives are tested against microorganism and compared with non-nano conditions. The resulting nanoparticles were characterised by X-ray diffraction and scanning electron microscopy. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Inhibiting angiogenesis by oral immunisation with poly(1-caprolactone)- poly(ethylene glycol)-poly(1-caprolactone) nanoparticle-encapsulated basic fibroblast growth factor

    Page(s): 221 - 225
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (242 KB)  

    Attempts to neutralise basic fibroblast growth factor (BFGF) have met some success in blocking neovascularisation. The authors describe an oral protein vaccine based on human BFGF encapsulated poly(ε-caprolactone)εpoly(ethylene glycol)εpoly(ε-caprolactone) (PCEC) nanoparticles. The human BFGF encapsulated PCEC nanoparticles (BFGF/PCEC) were monodisperse with the mean diameter of 142εnm and can slow-released BFGF in vitro. After mice were orally immunised with four dosages of BFGF/PCEC nanoparticles, BFGF-specific autoantibody titer in sera was 1600. Furthermore, alginate-encapsulated tumour cell assay implied that oral immunisation with BFGF/PCEC efficiently inhibited angiogenesis in vivo. Thus, oral immunisation with BFGF/PCEC nanoparticles may be a novel strategy to suppress angiogenesis, and this vaccine may have promising application in cancer immunotherapy. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ultra-thin porous silicon membranes fabricated using dry etching

    Page(s): 226 - 228
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (269 KB)  

    The fabrication of free-standing ultra-thin porous silicon membrane structures using xenon difluoride (XeF2)-based isotropic dry etching of thin silicon wafers is reported. Using this technique, the authors demonstrate 1, 5 and 10 m-thick porous silicon membranes that are stable and self-supporting and of relatively large surface area. By strategically choosing the etching parameters and conditions, membrane thickness and pore size can be tuned to produce porous silicon membranes with attractive features that could allow structural optimisation for different applications including biological sample filtering, sensing and drug delivery. The pore size, porosity and thickness of the various developed ultra-thin free-standing porous silicon membranes were characterised with scanning electron microscopy and optical transmittance measurements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Visible light-driven photodecomposition system: preparation and application of highly dispersed Pt-loaded WO3 microparticles

    Page(s): 229 - 232
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (325 KB)  

    A visible light-driven photodecomposition system was prepared by loading Pt nanoparticles on the surface of commercial WO3 microparticles via an improved in situ photoreduction method. The obtained well-dispersed Pt/WO3 microparticles were characterised by various means. Under visible light irradiation, the Pt/WO3 microparticles exhibit higher photoactivity than N-doped TiO2 nanoparticles. Pt shows almost no thermocatalytic activity towards the decomposition of organic compounds, and thus the high photoactivity of the catalysts can be attributed to the cooperation of Pt and WO3. The sample proved to be an efficient visible light-driven photocatalyst for the photodecomposition of the organic pollutant rhodamine B. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Synthesis and electrical properties of Na2Ti3O7 nanoribbons

    Page(s): 233 - 235
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (213 KB)  

    Electrical properties of Na2Ti3O7 nanoribbons (NRs) sensitively depend on their structures, morphologies and sizes. The nanofield-effect transistors based on single NR are fabricated to evaluate the electronic transport characteristics. A convenient hydrothermal method is employed to synthesise the NRs, and the characterisations of morphology and crystal structure reveal that the NRs have the good crystallinity and uniformity with the width of 200-400-nm, the length -10--m and the growth direction of [001]. The atomic ratio of Na:Ti:O is estimated to be 2:3:7 from the energy-dispersive X-ray spectroscopy spectrum. The electronic characterisations demonstrate that the as-synthesised Na2Ti3O7 NRs have a lower electronic resistivity of 14 cm, substantial p-type conductivity with a high mobility of 55.6 cm2 V-1 S-1 and carrier concentration of 8.1×1015 cm-3. The high aspect ratio and good crystallinity result in the high mobility. The Na2Ti3O7 NRs with good p-type conductivity may have important potential applications in nanoelectronic devices. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fabrication of polyimide microspheres with high precursor polymer concentration

    Page(s): 236 - 239
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (412 KB)  

    Polyimide (PI) microspheres with high precursor polymer concentration were successfully prepared using non-aqueous reverse emulsion polymerisation. The emulsion was composed of N, N-dimethyl formamide and liquid paraffin, in which Span85 was used as surfactant. The effect of Span85 concentration on the resulting PI product has been investigated. The results indicated that with the increase in Span85 concentration, the average diameter declined, and the size distribution became narrow. When the concentration of surfactant Span85 was around 0.15 w/w, a yellow-to-brown-coloured powder of PI microfine spheres was obtained, with an average particle size of 25.6 m. As an emulsifier and a chain termination agent, surfactant Span85 chemically bonded to the growing polymer chains, and not only formed stable non-aqueous inverse emulsion but also increased precursor polymer concentration. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Pattern buried oxide in silicon-on-insulator-based fabrication of floppy single-crystal-silicon cantilevers

    Page(s): 240 - 243
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    For the purpose of high-yield fabrication of single-crystal-silicon cantilevers based on a silicon-on-insulator (SOI) wafer, the internal compressive stress effect of the BOX has been investigated. The large stress in the BOX is responsible for the BOX cracking at the end of the bulk etching. For the cantilevers with comparable thickness with the BOX in the authors' experiments, the cantilevers break with the BOX cracking, which leads to the failure or low yield of the fabrication. Patterning the BOX has been proposed to release the stress and avoid the cantilever breaking. The yield based on this method is as high as 100', and the cantilevers show high quality factor and force sensitivity in vacuum measurements. Patterning the BOX effectually ensures the high-yield fabrication of cantilevers, especially meaningful for the floppy cantilevers. The method proposed here is also promising for the high-yield fabrication of other floppy sensors based on a SOI wafer. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Influence of solvent type on the characteristics and photocatalytic activity of TiO2 nanoparticles prepared by the sol-gel method

    Page(s): 244 - 248
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (246 KB)  

    TiO2 nanoparticles were prepared by the sol-gel method using methanol, ethanol and isopropanol as solvents and titanium tetraisopropoxide as a precursor. The prepared TiO2 nanoparticles were characterised by X-ray diffraction, scanning electron microscopy, nitrogen physisorption and UV-vis diffuse reflectance spectroscopy. The results indicated that the TiO2 nanoparticles prepared in isopropanol displayed pure anatase crystalline phase with the smallest crystallites having an average size of 11.4 nm. However, the TiO2 nanoparticles prepared in methanol and ethanol contained anatase- and rutile-mixed phases with anatase crystallite sizes of 15.6 and 14.5 nm, respectively. Nitrogen physisorption results showed that, compared to the TiO2 nanoparticles prepared with isopropanol, TiO2 nanoparticles prepared with ethanol had a greater pore volume and pore size, which led to their higher photocatalytic activity. The photocatalytic activities of the prepared TiO2 nanoparticles in the photodegradation of C.I. Basic Violet 2 (BV2) were compared to the activity of Degussa P25 TiO2. The maximum photodegradation rate of BV2, obtained from the TiO2 nanoparticles prepared in ethanol, was 3.5, 1.7 and 1.4 times greater than that of TiO2 particles prepared in isopropanol and methanol and the commercial Degussa P25 TiO2, respectively. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nonlinear optical properties of ultra-fine nanocrystalline sno synthesised through microwave-assisted hydrothermal route

    Page(s): 249 - 252
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (293 KB)  

    The purpose of this Letter is to prepare and investigate the nonlinear optical properties of nanocryatalline SnO. Using a microwave-assisted hydrothermal method, nanoparticles of SnO have been synthesised. It was noticed that, at 600 W microwave power, the pure tetragonal single phase of SnO existed and at higher-power SnO2 starts appearing. The grain size of SnO was ~3 nm and UV-vis measurements showed the existence of an excitonic peak at ~270 nm. The appearance of this excitonic peak for nanocrystallites SnO may be attributed to the conversion of bandgap from indirect in bulk SnO to direct bandgap in nanocrystallites. The third-order nonlinear optical properties of SnO nanoparticles were also studied using a continuous-wave He-Ne laser by z-scan technique. The nonlinear refractive indices of SnO nanoparticles were obtained from close aperture in order of 10-7 cm2/W with negative sign and the nonlinear absorption indices of these nanoparticles were obtained from open aperture with negative sign. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Droplet introduction into a pen-shaped portable reaction system by gravity and interfacial forces

    Page(s): 253 - 256
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (405 KB)  

    A pen-shaped platform that is similar to a mechanical pencil was proposed for producing the portable biochemical reaction system presented in previous work. The key component, the sample introduction unit, in the system was proposed in this work. The unit was fabricated by using a heat shrinkable tube. The sample droplet with the volume ranging from 6 to 36 l was successfully introduced into the unit by using the gravity force. The volume of the sample droplet could be expressed by the volume of the sample solution initially loaded into the tube, and the force equilibrium condition of the sample solution when the tube was perpendicular to the ground. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Synthesis, structural and optical properties of water-soluble Mn-doped CdS nanocrystals

    Page(s): 257 - 260
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (387 KB)  

    Water-soluble Mn-doped CdS nanocrystals were synthesised by an aqueous colloidal synthetic technique. X-ray diffraction identifies that the Mn-doped CdS nanocrystal is a cubic structure without impurity phase. Transmission electron microscopy suggests a narrow size distribution of the nanocrystals with an average particle size of ~3.6~nm. Moreover, UV~vis absorption and photoluminescence (PL) spectra of the nanoparticle were also measured. PL results show that Mn-doped CdS nanocrystals have a distinct Mn2+ related emission well-separated from the trap state emission. Reaction variables such as the 3-Mercaptopropionic acid/Cd (MPA/Cd) ratio, reaction temperature and Mn2+ doped concentration were systematically investigated to evaluate the impact of these variables on particle size and optical property. The results indicate that the 2 mol Mn-doped CdS nanocrystals synthesised at 70 C and the MPA/Cd ratio of 3.5 have the highest PL intensity. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Synthesis of silver nanocubes and nanorods through sodium-bromide-assisted polyol route

    Page(s): 261 - 264
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (289 KB)  

    Silver nanocubes and nanorods were prepared with the assistance of sodium bromide (NaBr) through a developed polyol route. The addition of different amounts of NaBr could tune morphologies of silver nanostructures. Transmission electron microscopy, high-resolution transmission electron microscopy, selected areas electron diffraction and X-ray diffraction were employed to characterise silver nanocubes and nanorods. The growth mechanisms of silver nanocubes and nanorods were discussed by taking account of the formation of single crystal and multiply twinned seeds, respectively. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Complementary metal-oxide semiconductor-compatible silicon carbide pressure sensors based on bulk micromachining

    Page(s): 265 - 268
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (317 KB)  

    This Letter presents a complementary metal-oxide semiconductor-compatible silicon carbide (SiC) absolute capacitive pressure sensor for harsh environmental applications. The pressure sensor was fabricated by bulk micromachining technology. Low-temperature SiC film was deposited by the plasma-enhanced chemical vapour deposition process and utilised as the moveable membrane of the device. Even though the deposited film has a good mechanical property and high chemical resistance, it takes low electric conductivity, thus tungsten(W) was used as the sensor's electrodes. This pressure sensor exhibits a linear response over a pressure range of 2 bars, with a total change of 507.1 mV (i.e. 0.274 pF). Furthermore, it is confirmed to withstand KOH etching for more than 30 min. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Shape-controlled synthesis of copper particles with high electrical conductivity behaviours

    Page(s): 269 - 272
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    A simple and cost-effective method for preparing copper particles is reported, which has the ability to shape the particle without using any capping agent or hard template. These samples were characterised by a variety of techniques, such as scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray detector and UV-vis spectrometer. In the synthetic procedure, the reaction temperatures and surfactant content exerted a strong influence on the shape of copper particles. In addition, the shapes of copper particles play an important role in UV-vis absorption and electrical conductivity properties. The absorption spectrum and electrical conductivity of copper particles showed obvious difference, which suggests the possible assembly of novel photocatalysts and high electrical conductivity functional materials. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electrochemical polymerisation of poly(3-bromothiophene)/WO3 nanocomposite films

    Page(s): 273 - 276
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (259 KB)  

    Poly(3-bromothiophene) (PBrT) was electrochemically synthesised on nano-WO3 surface in the ionic liquid 1-butyl-3-metyllimidazolium hexafluorophosphate ([BMIM]PF6) by potentiodynamic method. The PBrT/WO3 films were characterised by Fourier transform infrared spectroscopies, scanning electron microscopy and energy-dispersive X-ray analysis. Electrochemistry properties of the prepared PBrT/WO3 films were characterised by cyclic voltammetry. The obtained PBrT/WO3 nanocomposite films displayed a significant enhancement of electrochemical activity than that of pure WO3 and PBrT films. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Compound hertzian chain model for copper-carbon nanocomposites' absorption spectrum

    Page(s): 277 - 279
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (154 KB)  

    The infrared range optical absorption mechanism of carbon-copper composite thin layer coated on the diamond-like carbon buffer layer has been investigated. By consideration of weak interactions between copper nanoparticles in their network, optical absorption is modelled using their coherent dipole behaviour induced by the electromagnetic radiation. The copper nanoparticles in the bulk of carbon are assumed as a chain of plasmonic dipoles, which have coupling resonance. Considering nearest neighbour interactions for this metallic nanoparticles, surface plasmon resonance frequency (-0) and coupled plasmon resonance frequency (ω1) have been computed. The damping rate against wavelength is derived, which leads to the derivation of the optical absorption spectrum in terms of ω0 and ω1. The dependency of the absorption peaks to the particle size and the particle mean spacing is also investigated. The absorption spectrum is measured for different Cu-C thin films with various Cu particle size and spacing. The experimental results of absorption are compared with the obtained analytical ones. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Negative differential resistance in isolated GaN nanowires with focused electron beam deposited platinum contacts

    Page(s): 280 - 283
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    Straight and zig-zag isolated GaN nanowires were investigated for their electrical properties using focused ion/electron beam (FIB/FEB) deposited platinum contacts. The straight and smooth nanowire with FIB contacts was non-ohmic and relatively high leakage current was observed under reverse bias. The straight and smooth nanowire with FEB contact shows ohmic behaviour whereas the zig-zag nanowire shows non-ohmic with negative differential resistance (NDR). The peak-to-valley current ratio was about 4.5 at room temperature under forward bias. The NDR observed in the zig-zag nanowires has been explained based on inelastic tunnelling through electrically active acceptor-like defect states present within the bandgap. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

Micro & Nano Letters offers express publication of short research papers presenting research conducted at the forefront of micro- and nanoscale science, engineering and technology, with at least one dimension ranging from a few tens of micrometres to a few nanometres.

Full Aims & Scope

Meet Our Editors

Editors-in-Chief
Professor Gwo-Bin Vincent Lee
National Tsing-Hua University, Taiwan

Professor Peter Dobson
University of Oxford, UK