Online ISSN
1750-0443
Micro & Nano Letters
Volume 7, Issue 9, September 2012
Volumes & issues:
Volume 7, Issue 9
September 2012
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- Author(s): Ping-Quan Wang ; Yang Bai ; Jan-Yi Liu ; Zhou Fan ; Ya-Qin Hu
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 876 –879
- DOI: 10.1049/mnl.2012.0496
- Type: Article
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p.
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N, C-codoped BiOCl (BiOCl–NC) flower-like hierarchical structures were synthesised by an one-pot solvothermal process and characterised by X-ray diffraction patterns, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra, transmission electron microscopy and high-resolution transmission electron microscopy. As-synthesised BiOCl–NC showed higher photocatalytic activity in an aqueous RhB photodegradation system than pure BiOCl under visible light irradiation. The trapping experiments of active species during the photocatalytic reaction showed that the photocatalytic degradation of organic pollutants in the BiOCl–NC system proceeds through direct hole transfer and O2•− rather than •OH. - Author(s): Pan Yusong ; Wang Jing ; Pan Chengling
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 880 –884
- DOI: 10.1049/mnl.2012.0467
- Type: Article
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Functional gradient materials provided the authors with one new concept for artificial articular cartilage design with graded component and graded structure where one face of the material is high free water content, thereby providing excellent lubrication function and the opposite face of the material is high hydroxyapatite content, thereby improving the bioactivity of the material and stimulating cell growth. In this Letter, the functional gradient nanohydroxyapatite reinforced polyvinyl alcohol (nanoHA/PVA) gel biocomposites was prepared through a layer-by-layer casting method combing with freeze/thaw cycles technology. The microstructure and morphology were investigated by X-ray diffraction, transmission electron microscopy, scanning electron microscopy (SEM) and Fourier transform infrared. The results revealed that the size of HA particles in the biocomposites was on the nanometre scale. The nanoHA particles were distributed in a PVA matrix uniformly and it presented a needle-like microstructure because of the effect of PVA solution as a dispersant as well as soft template. The results of SEM observation showed that the microstructure of functional gradient biocomposites possessed micropores and lots of nanoHA powders in every layer. The size of micropores in the biocomposites presented a decreasing trend from the surface layer to the bottom layer. On the contrary, the nanoHA powders in the biocomposites increased from the surface layer to the bottom layer. This special structure of functional gradient biocomposites is beneficial for the improvement of lubrication and bioactivity properties of the biocomposites. - Author(s): Cuiling Zhang ; Chenguo Hu ; Na Wang ; Hulin Zhang ; Yi Xi
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 885 –888
- DOI: 10.1049/mnl.2012.0386
- Type: Article
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The perovskite BaMnO3 nanorods with fixed width of 60–100 nm and tunable length of 600–800 nm, 400–600 nm and 150–300 nm have been prepared by using a composite-hydroxide-mediated method with adding 0, 3 and 7 ml H2O. The ratio of surface area to volume (SVR) increases with decreasing length of the nanorods. The X-ray diffraction pattern of the nanorods indexes a hexagonal phase BaMnO3 with space group P63/mmc. Two absorption peaks are observed in ultraviolet–visible absorption spectra measured on the BaMnO3 nanorods at room temperature. The peak centred at 402 nm is sensitive to length of the nanorods. The band and density of states of BaMnO3 are calculated by density-functional theory. The results show that the peak centred at 402 nm is assigned to a transition of 2P↓ to Mn t2g↓states, while the peak centred at 301 nm is corresponding to the O 2P↑ to Mn eg↑ states. The increasing of SVR brings the more oxygen surface layer areas and oxygen vacancies, which decreases the bandgap, and leads to the red shift of emission and weakening of the absorption peak centred at 402 nm. - Author(s): Yilin Wang ; Kun Yang ; Huaqiao Pan ; Shengyan Liu ; Liya Zhou
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 889 –891
- DOI: 10.1049/mnl.2012.0439
- Type: Article
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By employing sodium selenite as selenium source and mercaptosuccinic acid (MSA) as stabiliser, the authors demonstrate that high-quality CdSe quantum dots (QDs) can be conveniently prepared in aqueous solution. The obtained products were characterised by UV–vis absorption, photoluminescence spectra, X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). XRD analysis showed that the MSA-capped CdSe QDs were of cubic zinc-blende crystal structure, UV–vis absorption spectra and TEM exhibited that the QDs were nearly monodisperse and relatively uniform. The quantum yield of as-prepared CdSe QDs can reach up to 18%, and the full-width at half-maximum value was merely 35 nm. - Author(s): Xiao-Jie Song ; Fan Yang ; Xianbiao Wang ; Han Xuan
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 892 –895
- DOI: 10.1049/mnl.2012.0426
- Type: Article
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Multi-walled carbon nanotubes (MWCNTs) were covalently modified with water-soluble β-cyclodextrin (β-CD) through ester bond. The products cyclodextrin-modified multi-walled carbon nanotubes (MWCNTs-COO-CD) were characterised by 1H-NMR, Fourier transform infrared spectroscopy and thermogravimetric analysis. The solubility of MWCNTs-COO-CD in water was 357.3 mg/l and no precipitates were observed after 18 months. The fluorescence spectra proved that the MWCNTs-COO-CD as a spectral probe could be used in the molecular recognition of β-naphthol (β-NOH), and the effective association constant (Ka) was calculated 2.22×104 from fluorescence spectra. By centrifugation at a speed of 16 000 rpm/min, the β-NOH with MWCNTs-COO-CD could be separated from water, collected and reused repeatedly. The results showed that the MWCNTs-COO-CD could be used to capture the aromatic pollutant such as β-NOH from wastewater. This study will widen the application of nanosupramolecule materials. - Author(s): M. Mousavi-Kamazani ; M. Salavati-Niasari ; H. Emadi
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 896 –900
- DOI: 10.1049/mnl.2012.0393
- Type: Article
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In this Letter, an ultrasonic method for the synthesis of CuInS2 nanostructure with the use of no surfactants is described. This method is facile and provides an appropriate condition for the preparation of structures with various morphologies. In this study, the effect of different parameters such as type of sulphur sources, concentration of precursors, time and power of ultrasonic irradiation on the morphology and the particle size were studied. The results indicated that the type of sulphur source plays an important role in the morphology of CuInS2. The synthesised materials were characterised by means of X-ray diffraction, energy-dispersive X-ray analysis, scanning electron microscopy, transmission electron microscopy, infrared spectrum and photoluminescence spectroscopy. CuInS2 nanoparticles were obtained after calcinations of the products at 350°C. The obtained results are discussed in detail. - Author(s): Xinkui Wang ; Xiaoying Tan ; Zhixin Zhang ; Chunyu Bao ; Christopher T. Williams ; Changhai Liang
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 901 –903
- DOI: 10.1049/mnl.2012.0401
- Type: Article
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Highly-dispersed noble metal nanoparticles (Au, Ag, Pd and Pt) supported on silica have been successfully prepared via reaction between modified silica and metal precursors in aqueous solutions, and the modified silica was synthesised through a sol–gel process of tetraethyl orthosilicate and 3-glycidoxypropyltrimethoxysilane (GPTMS) with aqueous ammonia as condensation catalyst. The transmission electron microscopy and X-ray diffraction results show that the noble metal particles are at nanoscale with good uniformity, and the diol species derived from 3-glycidoxypropyl groups of GPTMS are confirmed to serve as the reductants for metal precursors by solid state nuclear magnetic resonance spectra. The combination of noble metal nanoparticles and organic groups retained on silica would make the materials possess some special properties. - Author(s): Chao Guo ; Fangfang Shao ; Yingying Zhang ; Xiaobo Sheng ; Yinsheng Dong
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 904 –906
- DOI: 10.1049/mnl.2012.0383
- Type: Article
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In this Letter, silver/hydroxyapatite nanoparticles (nano-Ag/HA) were fabricated by depositing silver nanoparticles (nano-Ag) onto the surfaces of hydroxyapatite nanoparticles (nano-HA) using glucose as the reducing agent. The X-ray diffraction result shows that the deposition is pure nano-Ag. The transmission electron microscopy result confirms that the mean size of prepared nano-Ag decreased when decreasing the calcination temperature of nano-HA. The mean size of nano-Ag is about 4 nm whereas the maximal size of nano-Ag is about 7 nm when the calcination temperature of nano-HA is 450°C and the stabilising agent is soluble starch or polyvinyl pyrrolidone (PVP). Moreover, the mean size of nano-Ag fabricated using soluble starch as the stabiliser was smaller than the one gained using PVP as the stabilising agent and the size distribution of the former is narrower than the one of the latter, whereas the nano-Ag/HA fabricated with polyvinyl acetate or polyethylene glycolhad a bigger mean size and broader size distribution. - Author(s): Xiaoyan Zhang ; Ying Liu ; Jun Li ; Xiaojiao Yang
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 907 –909
- DOI: 10.1049/mnl.2012.0382
- Type: Article
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FeCo alloy nanofibres with an average diameter of around 150 nm were fabricated via the electrospinning technique using cobalt nitrate hexahydrate and ferric nitrate nonahydrate as precursors, polyvinyl pyrrolidone (PVP) as the fibre template. After being calcined at 600°C, the electrospun composite fibres became continuous crystallites as a result of the complete decomposition of PVP. The magnetic properties of the samples were characterised by vibrating sample magnetometer. Room temperature magnetisation results showed a ferromagnetic behaviour of the calcined FeCo nanofibres, which exhibit greatly enhanced coercivities compared with the bulk FeCo alloy materials. - Author(s): Y. Zhao ; J. Miao ; X.H. Wu ; L.J. Qiao ; X.G. Xu ; Y. Jiang
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 910 –913
- DOI: 10.1049/mnl.2012.0409
- Type: Article
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A method involving the combination of solution processing and high-temperature synthesis was developed to fabricate xBiFeO3/(1–x)BaTiO3 core–shell nanostructure with x from 0.6 to 1. It was found that both saturation magnetisation and dielectric properties of xBiFeO3/(1–x)BaTiO3 nanostructures increase with the content of BaTiO3 decreasing. Interestingly, the improved magnetic and dielectric properties were found in 0.8BFO/0.2BTO nanostructure. The authors attribute the enhancement of magnetic and dielectric properties to the core–shell nanostructure and morphotropic phase boundary in a BiFeO3/BaTiO3 nanostructure. - Author(s): Peng Miao ; Kun Han ; Ying Lin ; Tao Liu ; Pengli Bai ; Huancai Yin
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 914 –917
- DOI: 10.1049/mnl.2012.0455
- Type: Article
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Proteins-modified gold nanoparticles (AuNPs) have been considered as attractive materials in many fields especially in biosensing. In this Letter, the authors have studied the relationship between ratios of specific amino acids and protein–AuNPs interactions. A new indicator Rw/s, calculated from the ratios of certain hydrophilic amino acids, is proposed to reveal the affinity coefficient between proteins and AuNPs. Experimental results show that the proposed Rw/s can indicate the binding status of proteins and AuNPs effectively. The authors have also introduced alkaline phosphatase, a protein with relatively low Rw/s, for detection by the colorimetric shift based on strong protein–AuNPs interactions. - Author(s): Xianbiao Wang ; Jin Liu ; Wenzong Xu ; Tian Cao ; Xiaojie Song ; Congliang Cheng
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 918 –922
- DOI: 10.1049/mnl.2012.0477
- Type: Article
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In this Letter, a facile route to fabricate carbon materials with controllable microstructures by thermal treatment of thermosetting/thermoplastic polymers is presented. Porous carbon was prepared by carbonisation of polystyrene-poly(furfuryl alcohol) (PS–PFA) composites with PS spheres as hard template. The carbon spheres with diameter ∼2–3 µm were obtained through thermal pyrolysis of thermosetting PFA spheres, which were synthesised by polymerisation of furfuryl alcohol under sonication without surfactant. More importantly, the obtained carbon microstructures can be used as adsorbents for water purification, as illustrated by adsorption of methylene blue from contaminated water. The results show that the adsorption performance can be controlled by varying the microstructures of carbon based on thermal treatment of thermosetting/thermoplastic polymers. This Letter not only deepens the understanding of carbon microstructures derived from thermosetting/thermoplastic polymers, but also supplies novel adsorbents for water purification. - Author(s): Li Guoliang ; Peng Bing ; Chai Liyuan ; Jiang Lei
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 923 –926
- DOI: 10.1049/mnl.2012.0440
- Type: Article
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Spherical and dendritic nanometre silver is prepared by using the water-insoluble reducing agent o-phenylenediamine (OPD) in rapid-mixing and interface methods, respectively. Particle size and morphology of nanosilver are analysed using the scanning electron microscope and UV–visible spectrophotometer, whereas crystal structure characterisations are performed by X-ray. The effects of reactant ratio and concentration are investigated. The results show that optimal AgNO3 concentration range for growth of spherical nanometre silver is 0.6 mol/l and the optimal ratio of AgNO3 and OPD is 1:1 in the protection of polyvinylpyrrolidone. The mechanism of OPD reduction method would be reached and the reaction equation could be speculated by inductively coupled plasma and infrared spectrometry. - Author(s): M.H. Korayem and E. Omidi
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 927 –931
- DOI: 10.1049/mnl.2012.0293
- Type: Article
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Atomic force microscopes have been widely used for nanomanipulation in recent years. Since the task of nanomanipulation is tedious for humans, and it is desirable to have a proficient process, controlled manipulation in nanoscale is an extremely important issue. In this Letter, a compatible nanomanipulation model consisting of all effective phenomena in nanoscale for manipulation by variant substrate motion profile is proposed to perform an accurate manipulation task. The dynamic model of nanoparticle displacement utilises the Lund–Grenoble friction model, depicting the true stick–slip behaviour of the nanoparticle in manipulation. The sliding mode control approach is used to overcome the challenges in piezoelectric substrate motion control. It compensates drift, hysteresis and other uncertainties, to provide the desired substrate motion trajectory with the desired error dynamics. The final automated process provides satisfactory results with respect to experiments and enables automated manipulation, with associated savings in time and labour, and increased complexity of the resulting created structures. - Author(s): Yongdae Kim and Sejin Kwon
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 932 –935
- DOI: 10.1049/mnl.2012.0300
- Type: Article
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This Letter presents the effect of high-temperature glass frit bonding conditions on the resistivity coefficient of gauge factor (RCGF), resistivity and gauge factor of polysilicon strain gauges. In previous works, the authors proposed the use of thin polysilicon strain gauges that were bonded onto metal structures with an inorganic glass frit adhesive. However, this glass frit bonding process was carried out at a high temperature, which could cause performance changes of the polysilicon strain gauges in terms of their RCGF, resistivity and gauge factor. To investigate the effect of the glass frit bonding process, the RCGF, resistivity and gauge factor of the polysilicon strain gauge before and after heat treatment by the conventional Al annealing condition and the glass frit bonding condition were compared and evaluated. In the results, large resistivity and gauge factor deviations in the polysilicon strain gauges that were not heat treated were observed. In spite of these large deviations, a linear relationship between the resistivity and the gauge factor was observed. After the polysilicon strain gauges were heat treated by the conventional Al annealing condition and the glass frit bonding condition, the deviations in the values of the resistivity and gauge factor became more uniform than those seen in the strain gauges that were not heat treated. The RCGFs of the polysilicon strain gauges heat treated with the Al annealing condition and the glass frit bonding condition coincided with that of the gauge that was not heat treated. - Author(s): Yong-sheng Zhou ; Ying-chun Zhu ; Wei Dong ; Jing-jing Chen
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 936 –938
- DOI: 10.1049/mnl.2012.0456
- Type: Article
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Oriented assemblies of tantalum boride (TaB) nanowire bundles have been synthesised via a controlled thermal process. The products were characterised with scanning electron microscopy, X-ray diffraction, transmission electron microscopy and spectrofluorometry. The results show that the as-prepared products are composed of nanowires with a diameter of 60–100 nm. According to the analysis on the reaction mechanism between Ta and BN, a possible formation mechanism of TaB nanowire bundles was proposed. The TaB nanowire bundles displayed an intensive violet photoluminescence emission at around 417 nm. The special structures of the oriented assemblies of TaB nanowires may have potential application in nanoelectronics and photonics. - Author(s): Young Ku ; Yuan-Shu Chen ; Wei-Ming Hou ; Yiang-Chen Chou
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 939 –942
- DOI: 10.1049/mnl.2012.0488
- Type: Article
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Highly-ordered TiO2 nanotube arrays (TNTs) were prepared by anodisation in ethylene electrolytes containing 0.2–0.7 wt% NH4F. The dimension, chemical composition and optical characterisation of prepared TNTs were determined by the field-emission scanning electron microscopy, X-ray photoelectron spectroscopy and photoluminescence spectroscopy, respectively. Both the length and inner diameter of the prepared TNTs were increased with increasing NH4F concentration of electrolyte because of the faster electrochemical dissolution rate of TiO2. However, dimension of TNTs approached stable lengths and inner diameters as the NH4F concentration was higher than 0.3 wt%. The presence of Ti3+ state was observed for TNTs prepared with increasing NH4F concentration because of the charge compensation of the substitution of fluoride ions for oxygen ions. TNTs prepared in the electrolytes containing higher NH4F concentrations exhibited superior performance on the photocatalytic decomposition of Acid Red 4 possibly because more fluorides incorporated with TNTs to inhibit the recombination of electron–hole pairs. - Author(s): Ningning Song ; Hongxia Jiang ; Tianlu Cui ; Linling Chang ; Xinjun Wang
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 943 –946
- DOI: 10.1049/mnl.2012.0631
- Type: Article
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Mesoporous hierarchical α-Fe2O3 was prepared by a simple soakage process and followed by calcination, using eggshell membrane (ESM) as a biotemplate. The hierarchical architectures composed of interconnected hollow nanotubes replicated from ESM and showed a large surface area (45.57 m2 g−1). A possible formation mechanism of the hierarchical α-Fe2O3 was proposed. Benefiting from the mesoporous hierarchical structures and high surface area, the ESM-morphic α-Fe2O3 sensor exhibits enhanced gas-sensing performance. The results demonstrated that the sensor showed the highest selectivity and sensitivity to acetic acid among the tested gases, and rapid response and recovery times (18 and 4 s to 50 ppm of acetic acid). - Author(s): Hongfang Jiu ; Yuehua Fu ; Lixin Zhang ; Yixin Sun ; Yuanzhong Wang ; Tao Han
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 947 –950
- DOI: 10.1049/mnl.2012.0331
- Type: Article
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Y2O3:Tb3+ hollow microspheres have been successfully prepared on a large scale with polystyrene microspheres as templates followed by subsequent calcination. All X-ray diffraction peaks can be indexed to the pure cubic phase of Y2O3. Transmission electron microscopy and scanning electron microscopy images indicate that the average size of the hollow spheres is ca.1.3 µm and the thickness of the shells is ca. 50 nm. The microspheres show a strong green emission corresponding to the 5D4–7F5 transition of Tb3+ under ultraviolet excitation. The optimum Tb3+ concentration was 3 mol% to obtain the highest photoluminescence intensity. This study indicates that a calcining temperature of 800°C is needed for high luminescence efficiency. - Author(s): A. Mohammadi and A.B. Moghaddam
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 951 –954
- DOI: 10.1049/mnl.2012.0622
- Type: Article
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Direct electrochemical response of cytochrome c (cyt c) on the modified electrode was studied by cyclic voltammetry. The results indicated that cyt c could be adsorbed on the surface of the electrodeposited cobalt oxyhydroxide nanoparticles (CoOx NPs) modified electrode. A couple of well-defined redox peaks can be observed in a phosphate buffer solution (pH 7.0), whose formal potential, E°′ (defined as the average of reductive and oxidative peaks), was −86.5 mV with respect to the reference electrode equal to 110.5 mV against normal hydrogen electrode. Cyt c adsorbed on the surface of CoOx NPs shows a remarkable electrocatalytic activity for the reduction of oxygen. Based on these, a third-generation biosensor could be developed to detect the concentration of oxygen in aqueous solution. - Author(s): Sheikhi Moghaddam ; H. Farhangi ; M. Ghambari ; N. Solimanjad
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 955 –958
- DOI: 10.1049/mnl.2012.0641
- Type: Article
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The mechanical properties of sinter hardened Astaloy CrM were investigated as a function of post sintering cooling rate. Microstructural changes because of sinter hardening were correlated with tensile and fatigue behaviour to understand the influence of microstructures on mechanical behaviour. Hardness, yield strength, tensile strength and fatigue endurance limit all increased with an increase in cooling rate. The beneficial effect of sinter hardening on mechanical properties could be attributed to a change from a mixed microstructure in the as-sintered condition to a more homogeneous martensitic microstructure in the fully hardened condition. Fractographic studies showed that fatigue crack initiation was facilitated by surface pore clusters which impart high stress concentration at surrounding sintered necks leading to early crack initiation. The implications of microstructural changes because of sinter hardening on strain localisation at sintered necks, fatigue crack initiation behaviour and fatigue ratio of Astaloy CrM powder metallurgy steel are discussed. - Author(s): P.R. Jarosz ; A. Shaukat ; T. Mastrangelo ; C.M. Schauerman ; C.D. Cress ; R.D. Ridgley ; B.J. Landi
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 959 –961
- DOI: 10.1049/mnl.2012.0502
- Type: Article
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In this Letter, high-purity, KAuBr4-treated single-wall carbon nanotube (SWCNT) materials are utilised as outer conductors in coaxial cables. The attenuation/length is within Mil-C-17 specification and nearly equivalent to traditional copper outer conductors up to 3 GHz. The improved transmission performance is attributed to higher conductivity and density of the SWCNT network which creates enhanced nanoscale coverage to improve screening. The weight/length which can be achieved with SWCNT outer coaxial cables results in greater than 40% savings compared with conventional coaxial cables while maintaining a flexible cable design. - Author(s): Z. Vobecka ; R. Blue ; F. Vilela ; P.J. Skabara ; D. Uttamchandani
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 962 –964
- DOI: 10.1049/mnl.2012.0459
- Type: Article
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This Letter describes a fabrication of a microsensor incorporating a novel customised nitro-sensitive polymer derived from the propylenedioxythiophene family. Electrochemical polymerisation was used to selectively grow different types of localised polymer films on interdigitated electrode arrays, thereby fabricating miniature sensors that exhibited a highly selective and reversible response to chemical vapours containing ‘nitro’ (NO2) groups. Such nitro-bearing vapours are also present in trace quantities in the atmosphere in the presence of explosives. Vapours of nitropropane and nitrobenzene, serving as model analytes for explosives, were used for sensor testing. The sensors were demonstrated to have up to three orders of magnitude higher signal response to vapours from nitro compounds compared to other vapours commonly found in the atmosphere. The authors believe this is the highest selectivity to nitro compounds reported from a polymer-based chemicapacitor sensor. - Author(s): A.M. Elshurafa ; P.H. Ho ; A.G. Radwan ; M.H. Ouda ; K.N. Salama
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 965 –969
- DOI: 10.1049/mnl.2012.0642
- Type: Article
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This Letter introduces an electrostatically actuated fractal MEMS variable capacitor that, by utilising the substrate, extends the tuning range (TR) beyond the theoretical limit of 1.5 as dictated by the pull-in phenomenon. The backbone concept behind the fractal varactor is to create a suspended movable plate possessing a specific fractal geometry, and to simultaneously create a bottom fixed plate complementary in shape to the top plate. Thus, when the top plate is actuated, it moves towards the bottom plate and fills the void present within the bottom plate without touching it akin to how puzzle pieces are assembled. Further, a reasonable horizontal separation is maintained between both the plates to avoid shorting. The electrostatic forces come from the capacitance formed between the top plate and bottom plate, and from the capacitance formed between the top plate and the doped substrate. The variable capacitor was fabricated in the PolyMUMPS process and provided a TR of 4.1 at 6 V, and its resonant frequency was in excess of 40 GHz. - Author(s): Yinan Zhang ; Dong Jiang ; Hongyi Qin ; Zhuang Liu ; Haibo Zhang ; Zhenhua Jiang
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 970 –973
- DOI: 10.1049/mnl.2012.0603
- Type: Article
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Manganese-doped zinc sulphide nanoparticles capped with poly(ethylene glycol) (PEG) had been synthesised in aqueous solution by using PEG as surface modifier. The nanoparticles were prepared by chemical precipitation method at room temperature, which were characterised by the high-resolution analytical transmission electron microscope, X-ray diffraction (XRD), UV–visible and photoluminescence spectroscopy. Photoluminescene studies for all the investigated samples displayed characteristic band edge peak at about 430 nm. The broad peak at about 590 nm was ascribed to Mn incorporation. In addition, XRD and the high-resolution analytical transmission electron microscope studies showed the formation of cubic PEG-ZnS:Mn2+ nanoparticles with an average crystallite size of 3 nm. - Author(s): Jun Zhu ; Yue-Di Wu ; Hai-Tao Chen ; Xiang Xiong ; Xiao-Bing Chen
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 974 –977
- DOI: 10.1049/mnl.2012.0506
- Type: Article
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Large quantities of 3C-SiC nanowires (NWs) are synthesised under atmospheric pressure from the ball-milled SiO powders and activated carbon. The samples on the stack of carbon are determined to be pure 3C-SiC. 3C-SiC NWs synthesised at 1250 and 1300°C have a length of tens to hundreds of micrometres and a diameter of 40–80 nm. A higher synthesising temperature of 1350°C results in NWs together with nanoparticles. The nucleation of 3C-SiC NWs relates to vapour–solid reaction between SiO vapour and activated carbon. The residual oxygen in the chamber leads to the generation of CO gas, whose reaction with SiO vapour relates to the growth of the nanowires. There are two peaks at 416 and 439 nm in the photoluminescence line of the nanowires, which are ascribed to size confinement effect, defects and the oxygen vacancy in the amorphous SiO2 layer. - Author(s): Rongfang Wang ; Yilin Wang ; Wenxiu Xia ; Xingming Wei ; Bin Li ; Liya Zhou
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 978 –980
- DOI: 10.1049/mnl.2012.0540
- Type: Article
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Cd1−xMnxTe quantum dots (QDs) were synthesised through a one-step approach in an aqueous medium, and a red-shift in the emission peak wavelength, from 542 nm to a long wavelength of 566 nm, was observed by doping Mn2+ ions into the CdTe QDs. A red light-emitting diode (LED) device was fabricated by combining red light-emitting Cd1−xMnxTe QDs with a near-UV InGaN LED chip. CIE colour coordinates of the LED at (0.56, 0.25) demonstrated a near red light-emitting LED. The results showed that the Cd1−xMnxTe QDs are good candidates for LED applications. - Author(s): A. Dehzangi ; F. Larki ; S.D. Hutagalung ; E.B. Saion ; A.M. Abdullah ; M.N. Hamidon ; B.Y. Majlis ; S. Kakooei ; M. Navaseri ; A. Kharazmi
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 981 –985
- DOI: 10.1049/mnl.2012.0590
- Type: Article
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A side gate p-type junctionless silicon transistor is fabricated by atomic force microscopy nanolithography using a anisotropic potassium hydroxide wet etching process on low doped (105 cm−3) silicon-on-insulator wafer. The structure is a gated resistor and turns off based on a pinch-off effect principle, when essential positive gate voltage is applied and made a sufficiently large barrier in the gating region. Negative gate voltage is unable to make a significant impact on drain current to drive the device into accumulation mode. The experimental transfer characteristic is investigated and compared with the simulation result for positive gate voltage. ‘On/off’ ratio and subthreshold swing were also measured. The numerical study of the device in ‘off’ state is investigated based on the variation of majority and minority carriers’ density and recombination generation in the active region of the device, which offers more understanding of the device operation and also for previous works. - Author(s): M.H. Korayem ; S. Sadeghzadeh ; A. Homayooni
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 986 –990
- DOI: 10.1049/mnl.2012.0628
- Type: Article
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This Letter discusses the controlled positioning problem for scanning probe devices, especially the dynamic mode atomic force microscope. The necessity of real-time imaging in the nanoworld and the high sensitivity of nanoobjects make simulation-based works highly important. Here, a sufficiently accurate dynamic model has been provided and coupled with a dual control plan to lower the force of tip on the sample and consequently keep the sample from being damaged. First, the dynamic model has been validated using the available theoretical and experimental results, and the effectiveness of the suggested dual control plan has been demonstrated. Then, the effects of amplitude set point and piezo-tube and cantilever lengths have been studied, so that a lower tip-sample force and, simultaneously, a better image quality can be achieved. The obtained results show that the amplitude set point can be raised considerably to obtain a lower tip-sample force. Furthermore, the tip-sample force may be reduced by increasing the cantilever length, whereas the changing of the tube length has no effect. Although the presented results may be utilised to avoid some expensive tests before the nanorobotic operations, it is well suited to situations in which a soft or sensitive sample is scanned. - Author(s): Tao Zeng ; Yunan Zhao ; Wanzhong Ren ; Hongtao Cui
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 991 –993
- DOI: 10.1049/mnl.2012.0471
- Type: Article
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Monodisperse β-LiFe5O8 nanoparticles with high solubility in water were synthesised through a high-temperature hydrolytic sol–gel route, using propylene oxide as gelation agent. The route combines the advantages of the epoxide sol–gel process and the crystallisation process at elevated temperature in high boiling point solvent. In this approach, chlorinated propanol was produced through the protonation and ring opening reaction of epoxide. This hydrophilic compound functionalises the surface of formed nanoparticles in situ during the heating process, not only resulting in their high solubility in water, but also leading to the protection of the particle from aggregation and further growth. - Author(s): Libo Qian and Zhangming Zhu
- Source: Micro & Nano Letters, Volume 7, Issue 9, p. 994 –996
- DOI: 10.1049/mnl.2012.0598
- Type: Article
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RETRACTED
N, C-codoped BiOCl flower-like hierarchical structures
Preparation and characterisation of functional gradient nanohydroxyapatite reinforced polyvinyl alcohol gel biocomposites for articular cartilage
Size-tunable synthesis and structure analysis of BaMnO3 nanorods
Synthesis of high-quality CdSe quantum dots in aqueous solution
Preparation of β-cyclodextrin-modified multi-walled CNTs and its application in capturing β-naphthol from wastewater
Preparation of stochiometric CuInS2 nanostructures by ultrasonic method
Facile in situ preparation of noble metal nanoparticles supported on silica
Preparation of silver/hydroxyapatite nanoparticles using hydroxyapatite nanoparticles with different calcination temperatures
Preparation and magnetic properties of electrospun FeCo nanofibres
Enhanced magnetic and dielectric properties of BiFeO3/BaTiO3 core–shell nanostructure
Protein–gold nanoparticles interactions and its application for alkaline phosphatase assay
Preparation of carbon microstructures by thermal treatment of thermosetting/thermoplastic polymers and their application in water purification
Preparation of nanosilver by using water-insoluble reducing agent o-phenylenediamine
Robust controlled manipulation of nanoparticles using atomic force microscope
Effect of high-temperature glass frit bonding process on performance of polysilicon strain gauges
Oriented assemblies of tantalum boride nanowire bundles and their luminescent property
Effect of NH4F concentration in electrolyte on the fabrication of TiO2 nanotube arrays prepared by anodisation
Synthesis and enhanced gas-sensing properties of mesoporous hierarchical α-Fe2O3 architectures from an eggshell membrane
Preparation and luminescent properties of hollow Y2O3:Tb3+ microspheres
Direct electrochemistry and electrocatalysis of immobilised cytochrome c on electrodeposited nanoparticles for the reduction of oxygen
Effect of sinter hardening on mechanical properties of Astaloy CrM powder metallurgy steel
Coaxial cables with single-wall carbon nanotube outer conductors exhibiting attenuation/length within specification
Microelectrode sensor utilising nitro-sensitive polymers for application in explosives detection
Low-voltage puzzle-like fractal microelectromechanial system variable capacitor suppressing pull-in
Synthesis and photoluminescence study of poly(ethylene glycol)-capped ZnS:Mn2+ nanoparticles
Synthesis, structure and photoluminescence of cubic silicon carbide nanowires
New Cd1−xMnxTe quantum dots for application in light-emitting diodes
Numerical investigation and comparison with experimental characterisation of side gate p-type junctionless silicon transistor in pinch-off state
Coupled dynamics of piezo-tube and microcantilever in scanning probe devices and sensitive samples imaging
High-temperature hydrolytic sol–gel synthesis of monodisperse LiFe5O8 nanoparticles with high water solubility
Analytical heat transfer model for three-dimensional integrated circuits incorporating through silicon via effect - RETRACTED
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