Online ISSN
1750-0443
Micro & Nano Letters
Volume 6, Issue 10, October 2011
Volumes & issues:
Volume 6, Issue 10
October 2011
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- Author(s): A.B. Bandgar ; S.R. Sabale ; S.H. Pawar
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 816 –819
- DOI: 10.1049/mnl.2011.0369
- Type: Article
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p.
816
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A pure-phase anatase nanocrystalline TiO2 has been prepared at lower temperatures from aqueous peroxy titanium complex solution using titanium (III) chloride as precursor. The study on the reflux method has been carried out to investigate the effect of refluxing conditions on the characteristic properties of TiO2 and it has shown significant effects on the final product. The X-ray diffraction and UV–vis characterisations reveal that as refluxing time extended, the crystallite size increased and variation is found in bandgap energies. This is attributed to the effect of refluxing during the synthesis of nanocrystalline TiO2. A detailed study on the reflux method used for the synthesis of nanocrystalline TiO2 is reported. - Author(s): Chenhao Zhao ; Wenpei Kang ; Shiqiang Zhao ; Qiang Shen
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 820 –822
- DOI: 10.1049/mnl.2011.0378
- Type: Article
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820
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Submicron-sized orthorhombic LiMnO2 (O-LiMnO2) crystals with clear edges can be successfully prepared by a hydrothermal route using LiOH and porous Mn2O3 as precursors at 180°C for 16 h. As a reducing agent, hydrazine hydrate (N2H4·H2O) was introduced into the hydrothermal reaction systems of dark-green O-LiMnO2 at a N2H4·H2O:Mn2O3 molar ratio of 10.6:100, inhibiting the common impurity formation of red Li2MnO3 therein. At room temperature, the relatively purified O-LiMnO2 gives a high reversible capacity and good cyclability, showing a maximum discharge capacity of 216 mAh g−1 and a retention value of 200 mAh g−1 over 30 cycles at 0.1 C between 2.0 and 4.3 V, whereas the unpurified O-LiMnO2 showed a maximum discharge capacity of 200 mAh g−1, and fast decayed to 165 mAh g−1 during the 30th cycle. Moreover, cyclic voltammetry measurements and X-ray diffraction patterns of the cycled electrode materials prove the irreversible phase transformation of O-LiMnO2 to spinel LiMn2O4 upon cycling, suggesting that the easily Mn(IV)-doped synthesis of O-LiMnO2 hinder its potential application as lithium-ion battery cathodes. - Author(s): Yan Liu ; Wanzhong Ren ; Hongtao Cui
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 823 –826
- DOI: 10.1049/mnl.2011.0401
- Type: Article
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823
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A facile one-step procedure using epoxide as precipitation agent was applied to prepare paratacamite (γ-Cu2(OH)3Cl) nanoparticles with well-controlled size and morphology on a large scale at room temperature. The maximum production capacity in single reaction is as much as about 80 g, which is only limited by the volume of the facilities used in the laboratory. During the preparation, the hydrolysis of aquo complexes of metal ions was promoted by the ring opening reaction of epoxide through protonation of its oxygen. Owing to the low acidity of aquo Cu2+ complexes in solution, their partial hydrolysis occurred without further condensation of the generated hydroxide intermediate, resulting in the formation of precipitate instead of sol or gel. This induced the interposition of Cl− ions into intermediate to form the structure of γ-Cu2(OH)3Cl. The chlorinated alcohol compound, resulting from the reaction, functionalised the surface of particles, leading to the high re-dispersibility of obtained powder in water and ethanol. As confirmed by the characterisation results, the particle size increased with the increasing of Cu2+ concentration and reaction time. On the other hand, by changing the precipitation agent, the morphology of the particle was transformed from cubic shape under using propylene oxide to the spherical shape that was composed of agglomerated small nanoparticles by using cyclohexene oxide. - Author(s): Xiaojie Song ; Fan Yang ; Xianbiao Wang ; Kehua Zhang
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 827 –829
- DOI: 10.1049/mnl.2011.0428
- Type: Article
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p.
827
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Fe3O4 nanoparticles were introduced onto the surface of multi-walled carbon nanotubes (MWNTs) via in situ chemical precipitation method. The products (MWNTs–Fe3O4 nanocomposites) were characterised by X-ray powder diffraction, transmission electron microscope and vibrating sample magnetometer. The MWNTs–Fe3O4 nanocomposites were employed as a new adsorbent for dye removal. The adsorption results showed that adsorption efficiency of MWNTs–Fe3O4 nanocomposites was high for methylene blue. As a magnetic material, it could be separated easily from aqueous solution by an external magnet. - Author(s): Xiaohui Zhang ; Jinghong Ma ; Shuguang Yang ; Jian Xu
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 830 –831
- DOI: 10.1049/mnl.2011.0451
- Type: Article
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p.
830
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The well-defined block copolymer poly(acrylic acid)-b-poly(2-dimethylamino)ethyl methacrylate (PAA-b-PDMAEMA) was synthesised by sequential atom transfer radical polymerisation using protected group chemistry. The block copolymers exhibit the so-called ‘schizophrenic’ micellisation behaviour at different pH values. The PAA-core micelles and PDMAEMA-core micelles were formed in acidic pH (pH=3.4) and basic pH (pH=9.2), respectively. Different morphologies of ‘schizophrenic’ block copolymer particles: spherical micelles and worm-like reverse micelles were observed by transmission electron microscope and the ratio of gyration radius (Rg) to hydrodynamic radius (Rh). - Author(s): Wenjia Cui ; Qingze Jiao ; Yun Zhao ; Mingji Zhou
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 832 –835
- DOI: 10.1049/mnl.2011.0323
- Type: Article
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p.
832
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The carboxylate-intercalated layered double hydroxides (LDHs) were prepared using mixed hydroxides or oxides under a hydrothermal or refluxing reaction. The structure of the intercalated LDHs was confirmed by X-ray diffraction patterns and Fourier transform infrared spectra. The influence of preparation conditions on the morphology of the intercalated LDHs was investigated. The intercalated LDHs with high purity and crystallinity were obtained when the raw materials were freshly generated hydroxides. In the cases of oxides as starting materials, some impurities appeared. - Author(s): M. Edrissi ; S.A. Hosseini ; M. Soleymani
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 836 –839
- DOI: 10.1049/mnl.2011.0430
- Type: Article
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p.
836
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Pure spinel nanoparticles of copper chromite (CuCr2O4) were synthesised by coprecipitation method. The nanostructures and morphology of CuCr2O4 were investigated by powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and dynamic laser light scattering analyses. The X-ray analysis showed the formation of pure CuCr2O4 nanoparticles with good crystallinity. SEM and TEM images showed that particles were synthesised with nearly spherical crystalline shape. These results showed that this procedure is capable of producing pure CuCr2O4 with average particles size of 13.1 nm. Also, the experiments were optimised by the L8 Taguchi experimental design. The effects of seven main factors on the crystal size were evaluated. The most important factors on the crystal size reduction of CuCr2O4 nanoparticles were found to be type of precipitating agent, type of capping agent and calcinations temperature, respectively. - Author(s): MingXing Ma ; DaChuan Zhu ; MingJing Tu
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 840 –843
- DOI: 10.1049/mnl.2011.0237
- Type: Article
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p.
840
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Eu2+-doped BaAl2Si2O8 blue phosphor was prepared by the one-step calcination process of the chemical coprecipitation method. The phase structure, luminescence properties and morphologies of the samples were investigated by X-ray powder diffraction, fluorescence spectrophotometer and scanning electron microscopy, respectively. A tiny amount of BaAl2O4 phase was detected after adding polyethylene glycol (PEG) in precursor solution. The emission intensity increased with increasing PEG concentration at the beginning, and then decreased owing to the adverse enhancement of impurity phase and concentration quenching of Eu2+ ions resulted from addition of PEG. The emission peak position of the sample with 4 wt% PEG has a blue-shift compared with the other concentrations, which is attributed to Eu2+ emission mainly influenced by the Nephelanxetic effect. The morphology of particles changed from platelet or block to subglobular with increasing PEG concentration because PEG changed a nucleation process of crystal and gave rise to steric hindrance effect. - Author(s): A.M. Arabi ; T. Ebadzadeh ; A.A. Yousefi ; M. Pishvaei ; E. Marzban Rad ; C. Zamani
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 844 –847
- DOI: 10.1049/mnl.2011.0393
- Type: Article
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p.
844
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Hydrothermal synthesis of ZnS nanoparticles in the presence of polystyrene (PS) nanosphere templates has been investigated. Polyvinylpyrrolidone (PVP) as dispersing agent and ethylenediaminetetraacetic acid (EDTA) as chelating agent caused the gradual formation of ZnS–PS hybrid nanoparticles. Chemical compound and structural studies revealed the formation of ZnS sphalerite phase which was increased by reaction time. The size of the hybrid particles was in the range of 40–60 nm. The formation of the hybrid particles was confirmed by the variation of zeta potential against pH. The obtained nanoparticles could be stabilised in aqueous medium for more than 2–3 months. It was in agreement with the controlled growth of ZnS nanoparticles on the surface of PS templates. The red shift of adsorption edge (from 4.36 to 4.27 eV) with an increase of reaction time was due to the growth of ZnS particles in the quantum confinement region. - Author(s): Yigao Miao and Jiacheng Gao
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 848 –851
- DOI: 10.1049/mnl.2011.0484
- Type: Article
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p.
848
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This study reports a facile route to synthesise {010} facet-dominated anatase TiO2 nanorods with biconcave ends on the titanium substrate in the solution containing urea by the hydrothermal method. X-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy were employed to characterise the as-prepared samples. The research regarding reaction time, the amount of urea added, reaction temperature and volume of H2O2 added were employed to investigate the morphology evolution of the samples. The formation of cuboid-like anatase TiO2 nanorods was because of agent-capping and etching effect. The results indicated that urea played a key role in morphology control synthesis in addition to adjusting solution pH to affect deposition of film. - Author(s): Wei Liu ; Tongjian Niu ; Jinlong Yang ; Yanzhong Wang ; Shengliang Hu ; Yingge Dong ; Hong Xu
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 852 –854
- DOI: 10.1049/mnl.2011.0491
- Type: Article
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p.
852
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A new method to recycle aluminium beverage cans is investigated. Alumina (Al2O3) powders with primary grain size of 10–15 nm were synthesised by the hydrolysis-condensation process of aluminium ethoxide precursors. Here, aluminium ethoxide was prepared through the reaction of the recycling aluminium beverage can with ethanol. The resultant hydrolysates of ethoxide are converted to α-alumina phase after calcined at 900°C for 2 h. An average particle diameter of 0.26 µm was observed by the scanning electron microscopy. - Author(s): Chao Xu ; Shimin Liu ; Chaoqian Liu ; Wanyu Ding ; Shou Peng ; Weiping Chai
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 855 –857
- DOI: 10.1049/mnl.2011.0447
- Type: Article
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p.
855
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Highly dispersive and well crystallised aluminium-doped zinc oxide (AZO) nanoparticles (the mole ratio of Al to Zn was 0.02) were prepared by sol–gel combustion method. Two typical synthesised chemical reagents of urea and citric acid were employed to synthesise the AZO nanoparticles by investigating and comparing the physical properties and microstructural characteristics. The nanoparticles were characterised in detail by thermogravimetry and differential thermal analysis, bulk density measurement, transmission electron microscope and X-ray diffraction (XRD). The XRD patterns of AZO nanoparticles corresponded well to the hexagonal structure of pure ZnO, indicating that the Zn atom was substituted by Al atom. Small amount of urea in the precursor solution tends to generate larger amount of heat when the sol–gel is combusting. With increasing the content of urea in the precursor solution, the size of the prepared AZO nanoparticles varied from 17 to 25 nm. Simultaneously, obvious decrease in bulk density was observed when slightly increasing the ratio of the urea to the citric acid. - Author(s): O. Karatay and M. Dogan
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 858 –862
- DOI: 10.1049/mnl.2011.0440
- Type: Article
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p.
858
–862
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In electrospinning process nanostructured solid fibres are produced from charged polymer jet oriented at external electrostatic field. Materials such as polymer, composites and tissue scaffold fibres have been fabricated with electrospinning techniques. The typical obstacle of electrospun fibre production is the whipping instability, resulting from the chaotic oscillation of polymer jet. In this Letter, feasibility of suppressing the whipping instability is analysed and explained using a mathematical model based on the usage of secondary electrostatic field created by finite length hollow cylinder. It is shown that the three-dimensional path of polymer jet calculated by computer simulations focus the characteristic spot size of the deposited electrospun fibre to a smaller diameter, which is coherent to the experimental observations. - Author(s): Wenying Ma ; Huan Yang ; Ju Cai ; Weimin Wang ; Wei Xiong ; Jun Yao
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 863 –866
- DOI: 10.1049/mnl.2011.0496
- Type: Article
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p.
863
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Metal nanoparticles (MNPs) have potential uses in biochemical sensing applications owing to their localised surface plasmon resonance (LSPR) characteristics. In practice, selective biochemical sensors based on LSPR are constructed by MNPs and selective receptors for specific biochemical molecules. This Letter studies the effects of receptor thickness on LSPR sensing properties experimentally and theoretically. Experimental results demonstrate that an increase in polymethyl methacrylate (PMMA) receptor thickness induces a red shift of LSPR spectrum. For a 42 nm PMMA receptor, the maximum extinction efficiency is more sensitive to the test chloroform vapour than the peak wavelength. This receptor thickness effect is confirmed by electrodynamics calculations: a relatively thin receptor layer will create high peak wavelength sensitivity and low extinction efficiency sensitivity. However, it is the opposite for a relatively thick receptor layer. The turning point between thick and thin is approximately 20 nm in this Letter. These insights can be used as guidelines in fabricating high-sensitive LSPR-based biochemical sensors. - Author(s): L. Lonappan ; S. Issac ; R. Joseph ; D. Thomas ; K. Girish Kumar
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 867 –870
- DOI: 10.1049/mnl.2011.0384
- Type: Article
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p.
867
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A differential pulse voltammetric sensor for the determination of tamsulosin hydrochloride (TAM) using multiwalled carbon nanotubes (MWNTs)–Nafion-modified glassy carbon electrode (GCE) has been developed. MWNTs were dispersed in water with the help of Nafion and were used to modify the surface of GCE via solvent evaporation. At MWNT-modified electrode, TAM gave a well-defined oxidation peak at a potential of 1084 mV in 0.1 M acetate buffer solution of pH 5. Compared to the bare electrode, the peak current of TAM showed a marked increase and the peak potential showed a negative deviation. The determination conditions, such as the amount of MWNT–Nafion suspension, pH of the supporting electrolyte and scan rate, were optimised. Under optimum conditions, the oxidation peak current was proportional to the concentration of TAM in the range 1×10−3 M–3×10−7 M with a detection limit of 9.8×10−8 M. The developed sensor showed good stability, selectivity and was successfully used for the determination of TAM in pharmaceutical formulations and urine samples. - Author(s): C. Vézy ; N. Haddour ; N.M. Dempsey ; F. Dumas-Bouchiat ; M. Frénéa-Robin
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 871 –873
- DOI: 10.1049/mnl.2011.0492
- Type: Article
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p.
871
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The low-cost prototyping of complex lab-on-chip systems requires the development of simple techniques for the reversible bonding of microfluidic channels onto different substrates. The authors report on the use of dimethyl methylphenylmethoxy siloxane (DMPMS) spin-coated layers for the bonding of polydimethylsiloxane (PDMS) microchannels onto a substrate, using the common oxygen plasma method. The DMPMS layer adheres to various surfaces such as glass, silicon, gold, cyclo-olefin copolymer and tantalum and its thickness can be varied by diluting it with heptane. The authors show that the flexible polymer device constituted of the DMPMS layer and the PDMS microfluidic channel can be easily removed from the substrate, allowing the reuse of the latter. The proposed method was used to bond a PDMS microchannel onto an array of Ta-capped micromagnets and an application of this recyclable microfluidic device is presented. - Author(s): Ying Cao ; Ming-Li He ; Yan-Hua Zhang ; Hua-Jie Wang
- Source: Micro & Nano Letters, Volume 6, Issue 10, p. 874 –877
- DOI: 10.1049/mnl.2011.0448
- Type: Article
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p.
874
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Although the outstanding functions of conjugated linolenic acid (CLN) related to human health have gained increased popularity, there are limited applications about them in the daily life due to oxidation unstability. Here, β-cyclodextrin (β-CD) was applied as a carrier for CLN encapsulation. High-resolution transmission electron microscopy indicated that the CLN-loaded β-CD were nanoflakes, with about 50 nm in thickness. Fourier transform infrared spectrograph and UV-vis adsorption conformed that CLN was successfully loaded on β-CD with 97.8% of encapsulation efficiency and 10.5% of CLN loading. What's more important was that the oxidation stability of CLN was significantly improved by β-CD. It was found that only 35% of CLN oxidised in 280 h, whereas free CLN was oxidised completely at the same condition.
Synthesis of nanocrystalline titanium dioxide using refluxed aqueous peroxy titanium complex solution
Hydrazine–hydrothermal synthesis of pure-phase O-LiMnO2 for lithium-ion battery application
Large-scale synthesis of paratacamite nanoparticles with controlled size and morphology
Preparation of magnetic multi-walled carbon nanotubes and their application in active dye removal
‘Schizophrenic’ micellisation of poly(acrylic acid)-b-poly(2-dimethylamino)ethyl methacrylate: from spherical to worm-like micelles
Preparation of carboxylate-intercalated layered double hydroxides using mixed hydroxides or oxides
Synthesis and characterisation of copper chromite nanoparticles using coprecipitation method
Effect of polyethylene glycol on luminescence properties and morphologies of BaAl2Si2O8:Eu2+ phosphors
Hydrothermal synthesis of highly stabilised ZnS–polystyrene hybrid nanoparticles
Synthesis of {010}-faceted cuboid-like anatase TiO2 nanorods by the hydrothermal method
Preparation of micron-sized alumina powders from aluminium beverage can by means of sol–gel process
Effect of urea on the dispersibility and crystallisation of AZO nanoparticles prepared by sol–gel combustion
Modelling of electrospinning process at various electric fields
Effects of receptor thickness on localised surface plasmon resonance sensing performance
Electrochemical studies of tamsulosin hydrochloride using multiwalled carbon nanotube-modified glassy carbon sensor
Simple method for reversible bonding of a polydimethylsiloxane microchannel to a variety of substrates
Improvement of oxidative stability of conjugated linolenic acid by complexation with β-cyclodextrin
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