ALBERT

Description: A report is presented on a novel non-enzymatic amperometric glucose sensor based on three-dimensional porous Cu, which was directly reduced by hydrogen from Cu(OH) 2 . The surface morphology of the synthesised nanoporous Cu was characterised using field-emission scanning electron microscopy and X-ray powder diffraction. Compared with the commercial Cu nanoparticles, the nanoporous Cu modified electrode shows better catalysis to glucose, which is attributed to the special porous Cu structure providing a favourable microenvironment for glucose adsorbed in large quantity. The interesting comparative study of different cross-linking agents for the immobilisation of nanoporous Cu reports that nafion, chitosan and multi-walled carbon nanotubes (MWCNTs) can all improve the catalysis effect of porous Cu on the glucose but the MWCNT shows the best sensitive response and stability. The MWCNT plays an especially important role in stability improvement by 20% of the efficiency. Under optimal conditions, a linear dependence of the catalytic current upon glucose concentration was obtained in the range of 5.0 ?? 10 ??7 ??2.0 ?? 10 ??3 M with a detection limit of 1.0 ?? 10 ??7 M, a high sensitivity of 20.11 μA μM ??1 , good stability and no current response from interfering species at the approximate physiological concentration level.

Description: The design, synthesis and characterisation of biologically synthesised nanomaterials have become an area of significant interest. Presented is a report on the extracellular synthesis of gold nanoparticles using Punica granatum (Pomegranate) fruit extract as the reducing agent to synthesise Au nanoparticles. On treating aqueous chloroauric acid solutions with P. granatum fruit extract, rapid reduction of the chloroaurate ions is observed, leading to the formation of highly stable gold nanoparticles in solution. These nanoparticles showed an absorption peak at 536 nm in the UV??vis spectrum corresponding to the plasmon resonance of gold nanoparticles. Scanning electron microscopy analysis of the gold nanoparticles indicated that they ranged in size from 10 to 50 nm. The Fourier transform infrared spectroscopy spectrum confirmed the presence of main groups occurred in natural plant extract from P. granatum. The synthesised gold nanoparticles were active against Streptobacillus sp. and Escherichia coli.

Description: A novel nanocomposite was prepared by direct mixing of titania nanoparticles (nano-TiO 2 ) and gold nanoparticles (nano-Au)-modified carbon nanotubes (CNTs) in a solution of chitosan. The electrochemical performance of a TiO 2 /Au/CNT nanocomposite-modified electrode for hydroquinone detection was investigated. When measured at a scan rate of 50 mV s ?? 1, the detected amount of hydroquinone at the TiO2/ Au/CNT electrode varied linearly with hydroquinone concentration, for concentrations from 1 ?? 10 ??6 to 1 ?? 10 ??8 M; the sensitivity was 997 617 μA(mol 1 -l -1 ), and the detection limit was 1 ?? 10 ??10 M (S/N = 3). In all experiments, TiO2/Au/CNT nanocomposites exhibited better electrochemical performance than TiO 2 /CNT composites or CNTs. Enhanced current response can be attributed to the synergic effect of nano-TiO 2 , nano-Au and CNTs.

Description: An antibacterially bioinorganic composite has been synthesised by intercalating lysozymes (LZs) into layered titanates with a convenient and efficient exfoliation-restacking strategy. This composite exhibits a loose slab morphology with a thickness of 5??10 layers, and the interlayer space is ~4.4 nm because of intercalation of enzymes. The immobilised amount of lysozymes is up to ~68.3% in weight because of the layer-by-layer alternate and swollen structure. This composite is stable in the neutral and weakly acidic condition, and only releases 4 solution. The immobilised LZs exhibit excellent thermal stability, which retain their initial activities of about 70% at 70° for about 40 min. In addition, the residual activities of the immobilised enzymes are 68% after ten recycles reuse.

Description: Amlodipine besylate and atorvastatin calcium have been determined by the simultaneous voltammetric method at a multi-walled carbon nanotubes:graphite (MWCNTs:G) paste electrode. In comparison with a glassy carbon electrode, the prepared electrode showed an increase in the peak current because of the high electroactive surface area and excellent electronic conductivity of MWCNTs. The dependence of currents and potentials on pH were investigated for these components at the surface of the MWCNTs:G paste electrode. Differential pulse voltammetry was applied as a sensitive technique for simultaneous determination of the drugs in commercial tablets. By anodic differential pulse voltammetry, the calibration plot was linear in the range of 2.5??100 μg/ml with standard deviation between 2.7??7.1 and 1.8??8.3% for amlodipine and atorvastatin, respectively. The detection limit was 1 μg/ml at the prepared electrode in the buffered solution pH 6.

Description: Uniform CdMoO 4 nanooctahedra with tunable sizes have been synthesised via a facile and mild microemulsion method at room temperature. The reaction between CdMoO4 nanooctahedra and dilute hydrochloric acid was in situ monitored using microcalorimetry at 298.15 K, and microcalorimetric heat flow curves from this reaction process were obtained. Combined with an inductively coupled plasma optical emission spectrometer technique, the size effect of CdMoO 4 nanooctahedra on standard molar reaction enthalpy (Δ r HΘm) was studied. The results indicate that the value of (Δ r HΘm decreased with decreased particle size.

Description: For the first time, CoCr 2 O 4 /TiO 2 nanocomposite as a novel photocatalyst with different TiO 2 contents have been prepared by the sol??gel method. The techniques of X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM) have been employed to characterise the synthesised nanocatalysts. The XRD and TEM results indicated that CoCr 2 O 4 has a cubic normal spinel structure and the particle size of CoCr 2 O 4 is about 30 nm. As the first report, degradation of methylene blue and methyl orange is performed by CoCr 2 O 4 and CoCr 2 O 4 /TiO 2 nanocomposite under ultraviolet irradiation. The results showed that the rate of degradation of dyes with CoCr 2 O 4 /TiO 2 is much higher compared with that of CoCr 2 O 4 and TiO 2 . The photocatalytic activities were carried out under varying parameters such as irradiation time, the pH of the solution, the catalyst amount and substrate concentration.

Description: A report is presented on the local anodic oxidation of graphene film prepared by chemical vapour deposition using contact mode atomic force microscopy. Raman spectroscopy was used to check the uniformity and thickness of large area graphene film. Various kinds of patterns such as lines, ribbons and further, more complex structures, such as hexagons, two-terminal bar-like devices, were written by varying the tip voltage from ??6 to ??12 V and the tip speed from 60 to 200 nm/s. It was found that one can easily write any kind of patterns by just manipulating the tip voltage and tip speed instead of concentrating on other factors such as controlled humidity conditions, applied force on the tip and tip current. Also, it is confirmed that with an increase in tip voltage and by slowing the tip movement during lithography, one can write very narrow and sharp patterns which are important factors for the fabrication of graphene-based electronic devices.

Description: Hierarchical porous copper bulk can be fabricated through chemical dealloying of porous CuAl intermetallics under free corrosion conditions. The obtained precursor porous CuAl intermetallics and as-dealloyed hierarchical porous copper were characterised using X-ray diffraction, a field-emission scanning electron microscope and energy dispersive X-ray spectroscopy. It was found that the hierarchical porous copper can be easily prepared by this method. The dealloying solution will dramatically influence the morphology of the resultant hierarchical porous materials. As a result, trimodal porous copper composite material and bimodal porous copper can be achieved after being dealloyed in NaOH and HCl solutions, respectively. Therefore, the mechanisms of the evolution of hierarchical pores structure are also discussed.

Description: The ternary composites of graphene@SiO 2 @NiO nanoflowers were fabricated by a multi-step route. Graphene oxide (GO)@SiO 2 sheets were formed by a layer of silica nanosheets coated on the surface of GO. Then, GO@SiO 2 sheets were introduced as substrates for the growth of NiO nanoflowers. The microwave absorption property of the ternary composites was studied in the frequency ranging from 2 to 18 GHz, and the effect of the thickness of the ternary composites on microwave absorption was also investigated. The results indicate that graphene@SiO2@NiO nanoflowers composites exhibit enhanced microwave absorption compared with graphene@SiO 2 . The reflection loss of graphene@SiO 2 @NiO nanoflowers below ??10 dB is 5 GHz (from 10 to 15 GHz) and the maximum absorption is ??20.5 dB at 11.3 GHz with a thickness of 3 mm.

Description: Two kinds of planar-type potentiometric CO 2 gas sensors using thermal evaporated Li 3 PO 4 thin film as solid electrolyte were fabricated. Alumina plates with rough and smooth surfaces were used as the substrates of the sensors. X-ray diffraction analysis, atomic force microscopy and scanning electron microscopy were used to characterise the Li 3 PO 4 films. The sensing properties were investigated in the range of 500??5000 ppm CO 2 concentrations at 480°. Both the rough substrate-based sensor (r-sensor) and the smooth substratebased sensor (s-sensor) were sensitive to CO 2 gas and showed a good Nernst behaviour. The output electromotive force (EMF) of the s-sensor showed a more stable signal than the r-senor. The ??EMF/decade values obtained from the r-sensor and the s-sensor were 45 and 55 mV/decade, respectively. The response and recovery time were not primarily influenced by the electrolyte film. It was found that the sensitivity of the s-sensor was closer to the theoretical value. The results revealed that the substrate surface roughness may influence the characteristics of Li 3 PO 4 film and the response properties of the sensors to CO 2 .

Description: Bismuth oxybromide (BiOBr) flower-like microspheres have been successfully synthesised via a polyethylene glycol 600-assisted solvothermal process in the presence of reactable ionic liquid (IL) 1-hexadecyl-3-methylimidazolium bromide. The morphology and compositional characteristics of BiOBr were investigated by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and diffuse reflectance spectroscopy. During the reactive process, IL not only acted as a Br source but also as a template for fabrication of BiOBr flower-like microspheres. Photocatalytic activities of flower-like microspheres were evaluated by degradation of rhodamine B under visible-light irradiation. Compared with the BiOBr nanoplates, BiOBr hollow microspheres and TiO 2 (Degussa, P25), BiOBr flower-like microspheres exhibited excellent performance in visible-light-driven photocatalysis.

Description: Polyvinyl alcohol (PVA)/sodium dodecyl sulphate (SDS)/multi-walled carbon nanotubes (MWCNTs) composite nanofibres with various MWCNT contents (up to 10 wt%) were fabricated by electrospinning process and their microwave absorption properties were evaluated by a vector network analyser in the frequency range of 8??12 GHz (X-band) at room temperature. Scanning electron microscopy analysis of the nanofibre samples revealed that the deformation of the nanofibres increases with increasing MWCNT concentration. Very smooth surfaces of the composite electrospun nanofibres even for nanofibres with concentration of 10 wt% MWCNT have been successfully prepared because of the high stability dispersion of MWCNTs. It was observed that the absorption microwave properties improved by increasing the loading levels of MWCNTs. Finally, the PVA/SDS/MWCNT composite nanofibres sample with 10 wt% content of MWCNT has shown a reflection loss of 15 dB at a frequency of 8 GHz.

Description: Presented is a surface nanostructuring technology for enhancing the broadband light transmittance of polymethyl methacrylate sheets. Singleside and dual-side nanostructured sheets were fabricated by a hot embossing process using nanoporous alumina moulds. The fabricated nanostructured surfaces showed appreciable broadband light transmission characteristics because of the size distribution of their nanostructures. Single-side and dual-side nanostructured sheets showed a maximum light transmittance of 96.11 and 98.74%, respectively, whereas a pristine sheet showed a light transmittance of 93.54%.

Description: A novel thermochemical technique of depositing platinum nanoparticles (PtNPs) on a porous silicon (PS) substrate is demonstrated. Selfarranged macroporous structures, appearing as microtest tubes, are first formed on p-type, boron doped, 100 orientation silicon wafers, by the electrochemical etching method in hydrofluoric acid and N, N-dimethyl formamide solution. The macroPS substrate is then coated with PtNPs by a novel thermochemical procedure. It was observed that PtNPs deposited on the pore walls are able to arrive even at the bottom of the pores without blocking their openings. Such PtNPs-coated macroPS chips have potential biomedical applications as silicon and platinum are biocompatible.

Description: In this reported study, hydroxyapatite (HA) nanoparticle-contained bioactive glass (BG) nanofibres with an average diameter of 500 nm have been prepared by combining a sol??gelmethod and an electrospinning technique. Themechanical property of the as-prepared fibres demonstrated that the HA-BG nanofibres had far higher mechanical strength than pure BG nanofibres, and the in vitro simulated body fluid immersion experiment verified that the growth rate of the hydroxycarbonate apatite nanocrystals on HA-BG nanofibre surfaces was the same with pure BG nanofibres.

Description: SnO 2 nanocrystals with small diameters including nanorods, nanowires connected by nanorods and nanoparticles have been obtained in mixed solvents of oleic acid (OA) and ethanol. By simply adjusting the volume ratio of these solvents, the morphologies and structures of the SnO 2 crystals can be easily varied. All the products show pure tetragonal SnO 2 with a rutile structure and the obtained nanorods can be connected with each other in various ways to form nanowires. The nanocrystals with a volume ratio of OA and ethanol of 1:1 present the best photocatalytic properties which shows 100% degradation of Rhodamine B within 60 min.

Description: Ternary semiconductor ZnSe 0.7 Te 0.3 nanowires (NWs) are synthesised by using a thermal evaporation method, and the as-synthesised NWs have a wurtzite structure with a growth direction of [001]. The electrical measurements are carried out based on nano-field-effect transistors fabricated by individual NWs, and the electron transport characteristics reveal that the ZnSe 0.7 Te 0.3 NWs have p-type conductivity with a highmobility (μh) of 0.9 cm 2 V ??1 S ??1 and carrier concentration (n h ) 5 ?? 10 18 cm ??3 . Photoluminescence measurements for ZnSe 0.7 Te 0.3 NWs show a dominant emission peaked at 478 nm which is the emission of free exciton.

Description: The successful production, via two different oxidation processes, of metal-oxide-metal (MOM) diodes is presented. An innovative reactive ion etching and plasma assisted regrowth process has been used to provide oxides, which are in the thickness range 4.0??5.1 nm. These are thinner and physically more uniform than oxides grown in a furnace, resulting in diodes which should conduct via electron tunnelling across the MOM junction. Transmission electron microscopy analysis has been used in conjunction with time of flight secondary ion mass spectrometry analysis to verify oxide thickness and uniformity.

Description: During skeletal muscle development, correct cellular orientation is vital to generate desired longitudinal contraction for functional muscle fibres. In this reported study, submicron-imprint lithography was used to generate submicron-grooved surfaces on polystyrene plates to induce striated myotubes in vitro. Mouse muscle myoblast cells cultured on a submicron-grooved surface migrated faster in a directionally uniform fashion; in comparison, cells cultured on a flat surface grew and migrated slower in indiscriminate directions. Subsequent maturation of the myoblast cells formed along the submicron-groove surface resulted in a tandem of parallel myotubes that were both longer and greater in circumference than in the case of the flat surface. In a functional test, the co-culture submicron-groove-grown myotubes with neurotransmitter secreting cells further demonstrated contraction abilities, suggesting submicron-groove-guided growth served to enhance myotube formation while retaining striated motifs and physiological functionality for muscle tissue engineering.

Description: A simple process for nickel nanoimprint stamp replication is proposed. Based on this process, the replication of a 15 x 20 mm nickel nanoimprint stamp with 60 nm grating structures was carried out. First, the nanograting structures on the master silicon stamp were transferred to a polymer substrate using the hot embossing process; then, a layer of nickel was sputtered to fill the nanostructures on the substrate surface and form the seed layer for the electroforming process; finally, the back plane of the replica is electroformed. The observation results show good correlation between the dimensions of the master stamp??s features and the corresponding replicated features. The performance test result of the replicated stamp demonstrated that the mechanical strength of the replica is sufficient for the hot embossing process.

Description: The microstructure and geometrical dimensions of the scales on a butterfly Papilio peranthus Fabricius wing are obtained using scanning electron microscopy and transmission electron microscopy. Two kinds of scales are found in a butterfly wing and the structural colour mainly comes from the cover scale. Different structural models of cover scale that are related to ridge and concavity are constructed and their corresponding optical properties are investigated using the finite-difference time-domain method. It is concluded that the structural colour on the cover scale mainly comes from the sculpted multilayer structure and the ridge on the scale has few effects on the structural colour. When the curvature of the sculpted multilayer structure decreases, the dominant wavelength of colour will shift to a longer wavelength and move slower and slower. The two-dimensional planar multilayer model can be used to calculate the structural colour when the curvature exceeds a certain value.

Description: Interdigitated microelectrodes (IDμE) are always used as the sensing structure of a biosensor to detect the hormone content in the human body. To increase the sensitivity of the ID??E biosensor, the authors provide an improved method that utilises IDμE with nanodot arrays, that is, the nanodot arrays are put into the inter-electrode gap in IDμE. The nanodot arrays can reduce the conducting distance between microelectrodes, thereby reducing the resistance to electricity and improve the sensitivity of biosensors. The improved biosensor is composed of ID??E and nanodot arrays: the IDμE is made by microelectro mechanical system (MEMS) technology, whereas the fabrication of nanodot arrays makes use of the nanosphere lithography (NSL) technology. Double Cr/Au bilayers are used to make a conjunction between the MEMS and NSL process. The biosensor based on the IDμE with nanodot arrays was used in the detection of low-level thyroid-stimulating hormone (TSH), and proved to provide about three times sensitive detection than the biosensor without nanodot arrays. The TSH detection limit of the biosensor based on the IDμE with nanodot arrays can reach 0.005 mIU/l. The improved biosensors can be used in the detection of other hormones, which are critical for disease intervention strategies.

Description: The nanofabrication of nanometre-scale multiple-level structures by nanoimprint lithography and CF 4 /O 2 etching rates was investigated for nanoelectro mechanical systems and three-dimensional (3D) wafer-level packaging. A TiO 2 ??SiO 2 sol-gel photocurable material with high titanium concentration of 20.9 wt% was developed for CF 4 /O 2 etch selectivity with a pattern transferring carbon layer in a bi-layer process. The nanostructures of 3D micropatterns, holes with 200 nm diameter and 130 nm-wide dense lines with line edge roughness of ~10 nm were provided. The CF 4 /O 2 etching rate of the TiO 2 -SiO 2 photocurable material was ~3.7 times lower than that of the referenced SiO 2 sol??gel photocurable material. The CF 4 /O 2 etch rates of titanium-based photocurable materials were confirmed for deep plasma etching processes.

Description: A report is presented on the preparation of surface-functionalised nanosilica from silicon tetrachloride (SiCl 4 , one of the major by-products in the polycrystalline silicon industry) by in-situ surface modification in aqueous solution. The approach uses both SiCl 4 and sodium metasilicate as the silicon sources to generate nanosilica, whereas the proportion of sodium metasilicate and SiCl 4 is adjusted to control the pH value of the reaction system. In this way, desired SiO 2 nanoparticles were in-situ surface-modified by hexamethyldisilazane as soon as they were generated in the reaction solution, which makes it feasible to prevent the severe aggregation of nanosilica that often happens during the hydrolytic process. The obtained nanosilica with uniform particle size distribution (mean diameter 35??40 nm) shows superhydrophobicity (a water contact angle of 165°) and excellent organic dispersibility. Thanks to the low cost of raw materials as well as the superhydrophobicity and lipophilicity of as-prepared nanosilica, its application for improving the selective penetration of oil is primarily investigated. The result shows that quartz sand modified by as-prepared nanosilica can separate diesel oil from water successfully, which could be significant for improving crude oil recovery efficiency.

Description: Biomaterials is a term used to indicate materials that constitute parts of medical implants, extracorporeal devices, and disposables that have been utilised in medicine, surgery, dentistry and veterinary medicine as well as in every aspect of patient health care. Ceramics biomaterials are used as components of hip implants, dental implants, middle ear implants and heart valves. Porous or particulate calcium phosphate ceramic materials such as tricalcium phosphate (TCP) have proved successful for resorbable hard tissue replacements when low loads are applied to the material. The aim of the present work was to evaluate the biological characteristics of the biomaterial developed. Interactions of TCP with polyacrylate polymers in aqueous dispersions were characterised using X-ray diffraction, Fourier transform infrared spectroscopy, pH determination and viscosity measurements.

Description: Fe 3 O 4 ??ZnWO 4 composite microspheres with magnetically recyclable photocatalytic performance have been firstly synthesised by a simple refluxing method under mild conditions. The as-prepared Fe 3 O 4 ??ZnWO 4 composites show good photocatalytic efficiency in degradation of rhodamine B under UV light irradiation and can be recycled five times by magnetic separation without major loss of activity, the magnetic property of Fe 3 O 4 ??ZnWO 4 sample has been studied also. Microspheres show potential use on dye degradation from the solution considering their magnetic recovery properties.

Description: Compact equivalent circuit models for single-walled carbon nanotube (SWCNT) bundles are described, and the performance of SWCNT bundle interconnects is evaluated and compared with traditional Cu interconnects at different interconnect levels for through-siliconvia- based three-dimensional integration. It is shown that at local level, carbon nanotube bundle interconnects exhibit lower signal delay and smaller optimal wire size. At intermediate and global levels, delay improvement becomes more significant with technology scaling and increasing wire lengths. For 1 mm intermediate and 10 mm global level interconnects, the delay of SWCNT bundles can reach 45.49 and 51.84% of that of Cu wires, respectively.

Description: Thiyoglycolic acid-capped CdSe nanoparticles have been synthesised at 273-279 K. A comparative study on the structural and optical characteristics of the as-synthesised and annealed samples is done using state-of-the art instruments and software. Based on these studies here the authors report a colossal change in crystallinity, particle size and red shift in the absorption spectra upon annealing. Lattice strain is also found to increase by 18.77% upon annealing. Excitation wavelength-dependent photoluminescence with giant Stokes shift and narrow full-width at half-maxima of both the samples is also reported, which may be useful for device application.

Description: In this reported work, a microfluidic-based fluid electrokinetic force has been used for surface plasmon resonance or surface plasmon resonance image (SPRI) detection. In this device, a modified rectangular microarray of Au instead of previous reported square or circular gold segments was designed and microfabricated with gold segment geometries and characterised by surface morphology studies. A voltage drop of maximal 400 V/cm was applied without gold erosion to drive fluorescein isothiocyanate isomer I in a high-conductivity medium on the bare gold surface layer, enabling SPRI detection.

Description: A report is presented on a new multi-mode nanofabrication method that uses a compliant conductive atomic force microscope (AFM) probe for both AFM and scanning tunnelling microscope (STM) operation and it is demonstrated that these modes can be switched 'on-the-fly' during the measurement or fabrication of nanostructures. The authors oxidised Ti with the same conductive AFM probe in AFM and STM modes, alternately in a continuous writing step. An in-plane Ti??TiO x ??Ti junction was fabricated by combining AFM and STM modes and electrically characterised by taking current images in conductive AFM mode. After measurement, additional features were written to increase the electrical isolation, thus realising in situ nanoscale modification.

Description: The hexagonal rotor-like cerium carbonate hydroxide (CeCeO 3 OH) and CeCeO 2 nanostructures were successfully synthesised via a facile hydrothermal method using Ce(NO 3 ) 3 ?? 6HCeO 2 O as the cerium resource, HNOCeO 3 additive to form an acidic solution, CO(NHCeO 2 ) 2 as both precipitator and carbon source and polyvinylpyrrolidone as surfactant. Characterisation techniques using an X-ray diffractometer, scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy, thermogravimetric differential thermal analysis apparatus and UV??vis absorption spectrum have been used for studying the roles of Ce(NO 3 ) 3 ?? 6H 2 O and HNO 3 . It was found that the amount of Ce(NOCeO 3 ) 3 ?? 6H 2 O has an obvious effect on the morphology of the as-synthesised CeCO 3 OH and CeO 2 nanostructures, whereas HNO 3 has a significant influence on the crystalline phase. CeOCeO 2 has a higher UV absorption than as-synthesised CeCOCeO 3 OH, which is likely associated with the charge-transition between Ce3 + and Ce4 + .

Description: The electrocatalytic performance of commercial PtRu/C is significantly enhanced by directly mixing a few SnO 2 nanoparticles. The composite catalysts show enhanced CO oxidation, higher activity and better stability than commercial PtRu/C. Among the different ratios of SnO 2 nanoparticles (10??40%), the SnO 2 ??PtRu/C (20%) composite catalyst shows the best catalytic activity for methanol oxidation. The effect of temperature on methanol oxidation was also investigated and the apparent activation energy (E a ) value of catalyst was obtained. The results here suggest a simple route to enhance the catalytic efficiency for commercial PtRu/C catalyst.

Description: Different shapes of silicon (Si) nanotip arrays using reactive ion etching with various mask patterns were fabricated, and the surface profile, surface roughness and quantitative etch characteristics of the Si nanotip were characterised. It was found that the geometry as well as etch characteristics of Si nanotip arrays could be modified by changing the initial mask patterns. Pyramidal and conical shaped Si nanotips could be obtained from square and circular mask patterns, respectively. The alternate square array pattern resulted in a Si nanotip with a wavy array whereas the honeycomb mask pattern resulted in a Si nanotip in a hexagonal array. In terms of etch rate, the circular pattern mask showed faster etching than the square patterns. Also, the parallel pattern showed faster etching than the alternate pattern under the same conditions. The tip size and height of Si nanotip structures determined by atomic force microscopy measurement were in the range of 50??80 and 450??750 nm, respectively.

Description: The quartz double-ended tuning fork (DETF) resonator is well known to be sensitive to longitudinal force and is widely used as the sensing element in modern accelerometer, force and pressure sensors. The quartz DETF resonator works in-plane, with anti-phase flexural mode vibration, which is driven into oscillation by internal strains created by AC voltages applied to electrode patterns on the beams. The DETF vibration modes and vibration characteristics are determined by the electrode pattern and its electromechanical coupling efficiency. Presented are three kinds of electrode patterns for different applications, and the effect of electrode patterns on the vibration performances are investigated experimentally. With the fundamental frequency at 65 KHz, the DETF resonator is designed and fabricated using the wet etching-based quartz MEMS technique. The vibration characteristics including Q-value, and equivalent parameters, are evaluated using a 4294 A impedance analyser. Experimental results demonstrated that the vibration characteristics of quartz DETFs are affected by the electrode patterns including pattern location and widths. These results are expected to be useful for designing quartz DETF based devices.

Description: This study presents a lead zirconate titanate (PZT) energy harvester with stainless steel (SUS 304) substrate the resonance frequency of which is lower than 100 Hz. The PZT thick films had been directly and successfully deposited on SUS substrates by the sol-gel method with a thickness of 4 μm. Then the deposited films were evaluated by the X-ray diffraction method and the scanning electron microscopy method. Energy harvesters were fabricated and their performance was measured under various vibration conditions. Optimal output power and resonant frequency are 15 μW and 89 Hz, respectively, when the devices were tested under 1 g acceleration vibration and connected with a 23 kΩ resistor.

Description: Flexible dye-sensitised solar cells (FDSSCs) which have different quantities of arrayed titanium dioxide (TiO 2 ) working electrode for parallel modules are introduced. FDSSCs are usually fabricated as a module type instead of single cell to enhance conversion efficiency and characteristic parameters. The general FDSSCs modules are designed as parallel strip-shaped and as parallel interconnection types, and there are some advantages such as easy fabrication, low cost and simple structure. In this reported study, the active areas of FDSSCs are the same (0.48 cm 2 ), and they have different quantities of TiO 2 thin films. The single strip-shaped TiO 2 working electrode has a larger internal resistance than more quantities of TiO 2 thin films. Therefore, and they have fabricating the different quantities of arrayed flexible TiO 2 working electrodes is the better method to solve the problem, higher internal resistance than single TiO 2 thin film. As a result, the FDSSC, which has the triple strip-shaped TiO 2 working electrode, has a higher conversion efficiency (0.25%) than other different quantities of TiO 2 thin films.

Description: The sixth Asia-Pacific Conference on Transducers and Micro/Nano Technologies (APCOT 2012) was held between 4th and 7th of July in Nanjing, China. It was technically co-sponsored by IEEE Nanjing Section. Annually, the conference provides an opportunity for engineers from the diverse worlds of academia, industry and research institutions to share the latest developments in the field. The topics covered were similarly varied, ranging from sensor technology and microsystems (both physical and biological) to optical MEMS and nano devices.

Description: By analysing the energy flow in a piezoelectric generator, it was revealed that the mechanical factor, electromechanical coupling coefficient and dielectric loss of the generator have significant influence on its energy conversion efficiency. Based on this analysis, aluminium nitrate (AlN) thin films deposited on stainless steel (SUS) were selected to substitute lead titanate zirconate thin films deposited on single-crystal Si for fabricating miniature devices. These thin films were prepared with an electron cyclotron resonance sputtering system. The influences of the surface modification (polishing or coating a Pt/Ti thin layer) of SUS substrates on c-axis orientation, piezoelectric coefficient and effective coupling coefficient of AlN thin films were investigated.

Description: Presented is a microsupercapacitor using SU-8 photoresist as the separator, featuring by high-aspect-ratio three-dimensional (3D) electrodes and high capacity per unit area. A scalable and mechanically stable structure for microsupercapacitors has been designed. By combining the preparation strategy for self-supporting nanoporous electrodes with micromachining technologies for high-aspect-ratio structures, 3D electrodes that allow for a heavy load of electrode material per unit area has been achieved. Electrochemical characterisation results of the prototype using ionic liquid as the electrolyte demonstrate that the microsupercapacitor exhibits a high specific energy of 330 mJcm –2 and a large specific capacitance of 160 mFcm –2 , which are attributed to both the high-performance materials and the well-designed microstructure. This device can be potentially applied to various energy systems, such as electronic backup power supplies and microenergy storage devices.

Description: A nickel–chromium (Ni –Cr) piezoresistive pressure sensor is presented, which has the advantages of low-cost and easy fabrication processes. In the designed sensor, Ni –Cr alloy (80:20 wt%), which can be fabricated using simple processes, is used as the strain-detecting material with a smaller but acceptable gauge factor. Eutectic-bonding technology, based on silver –tin (Ag –Sn) alloy, which contains 3.5 wt% Ag and has 20 mm thickness, is used as an alternative and easy bonding choice to complete the vacuum package. Normally, Ag –Sn alloy is mostly obtained by the electrochemical deposition method. However, here the Ag –Sn solder film is directly used as a bonding material. It reduces the fabrication difficulty of eutectic bonding of the proposed pressure sensor. By studying the processes of annealing of Ni –Cr fabrication and eutectic bonding with Ag –Sn, the authors complete the alloy piezoresistive atmosphere pressure sensor. Bonding quality is evaluated by inspection through the deflection of a diaphragm of silicon with more than 95% of the area successfully bonded. The pressure –voltage characteristic test results suggest a precision within 0.3% in square fitting. The temperature coefficient offset is 620 ppm/(°C free space optic (FSO)).

Description: Blind cave fish are capable of sensing flows and movements of nearby objects even in dark and murky water conditions with the help of arrays of pressure-gradient sensors present on their bodies called lateral-lines. To emulate this functionality of lateral-lines for autonomous underwater vehicles, an array of polymer MEMS pressure sensors have been developed that can transduce underwater pressure variations generated by moving objects. Individual sensors are fabricated using liquid crystal polymer as a membrane material, which gives high robustness and reliability, and higher sensitivity compared with its silicon counterparts. The individual sensor in the array achieves a sensitivity of 90 mV/ (m/s) with a high resolution of 25 mm/s. The underwater object detection capability of the array is demonstrated through proof-of-concept experiments. The array is capable of determining the velocity and distinguishing various distances of an underwater stimulus with high accuracy and repeatability.

Description: Flexible and highly-sensitive capacitive sensors that are capable of detecting pressure distribution on curved surfaces are now in demand. Using solid dielectric material could limit the sensors flexibility, while using air as the dielectric might compromise the sensors sensitivity. Proposed is a distributed capacitive sensor that contains highly dielectric liquid, which increases the sensor sensitivity while maintaining their flexibility. Since the liquid used in this work is incompressible, an escape reservoir is used that allows the liquid between the electrodes to flow into the reservoir when external pressure is applied and the gap between the electrode decreases. In prior work, the escape reservoir was designed to be alongside the sensing area, which resulted in a large footprint. A sensor has been designed that contains encapsulated highly dielectric liquid and allows the liquid to escape beneath the sensing area. The footprint was successfully reduced by 75%. The encapsulated liquid enhanced the maximum measurable pressure from 100 kPa to 800 kPa. The amplification ratios of the sensitivity with DI water and glycerine increased 7 and 3.5 times respectively, as compared to the device without the liquid encapsulated.

Description: In this study, the characterisation and calibration of microfabricated cobalt electrodes for the detection of total phosphorus (TP) in water are presented. The microelectrode chips were fabricated by microelectromechanical systems technology, and cobalt was used as the sensing material modified on the surface of microelectrodes using the electrodepositing method. The surface morphology and crystal direction of modified cobalt were examined and the electrochemical characterisation of cobalt electrodes was performed. The cobalt microelectrode showed good linear response to phosphate in the range of 10 –6 –10 –2 M/l with the slope of about 28 mV/dec. The microelectrodes also presented good stability, consistency and reproducibility. These electrodes were applied to detect TP concentration in water samples from a lake. Calibration was performed for each electrode before the test. The test result using these cobalt microelectrodes was consistent with the concentration given in the certificate of qualified water of the quality detection institute.

Description: A Love wave biosensor, which is composed of a one-port surface acoustic wave reflective delay line on a piezoelectric substrate, a thin overlayer (waveguide layer) on top of the substrate, and a sensitive film that responds only to a specific cell, was optimally designed on a 41° YX LiNbO 3 substrate and then fabricated according to the extracted design parameters. Based on multilayer theory, polymethylmethacrylate waveguide thickness was optimised. For derivation of the coupling of mode parameters, the periodic using the periodic finite-element method/boundary element method modelling was utilised. Optimal interdigital transducers and reflectors?? features were determined to realise high-quality reflection peaks. The experimentally measured reflection coefficient S 11 showed good agreement with simulated results. The evaluated sensitivity was 11.5 deg/μg/ml in terms of anti-DNP immunoglobulin G absorption.

Description: A report is presented on the modelling and verification of microneedle-skin interactions. A nonlinear finite element model based on the micro biomechanical properties of skin was established to simulate a microneedle being inserted into the skin. The deformation of skin and the forcedisplacement behaviour of the microneedle could be obtained. The accuracy was experimentally verified by measuring the relationship between force and displacements during insertion into mouse skin. With this model, the influences of different geometries on microneedle fracture were discussed, which was useful to optimise the microneedle design.

Description: Presented is a piezoresistive absolute micro pressure sensor, which is of great benefit for altitude location. In this investigation, the design, fabrication and testing of the sensor are carried out. By analysing the stress distribution on sensitive elements using the finite-element method (FEM), a novel structure through the introduction of beams into the standard bossed diaphragm is built up. The proposed configuration presents its advantages in terms of sensitivity and overload resistance compared with the standard bossed diaphragm and conventional plane diaphragm structures. The sensor is fabricated based on silicon bulk micromachining technology, and the detailed processing program is discussed. Calibration data obtained through measurements are in good agreement with the results of the FEM analysis. Testing results demonstrate that the sensor features a high sensitivity of 11.098 μV/V/Pa in the operating range of 500 Pa at room temperature, and a high-overload resistance (200 times overload) to protect it from being destroyed under atmospheric environment. Owing to the excellent performance, the sensor can be applied for measuring absolute micro pressure lower than 500 Pa.

Description: Collagen has been widely used as biomaterials for its excellent biocompatibility and the potential to guide tissue regeneration. Based on the inducing regeneration concept, collagen/biphasic calcium phosphate microspheres (BCP) were prepared by utilising emulsion polymerisation and the intrinsic self-assembly of collagen. The bioactivity of the micro collagen/BCP composites was preliminarily evaluated by in vitro co-culture with mesenchymal stem cells (MSCs) and the results indicated that the composites can provide an appropriate environment for the proliferation and osteogenic differentiation of MSCs and have a potential clinical application in the bone tissue engineering field.

Description: In this study, substrates with a large topography were aligned and bonded, and a spray-coated SU-8 was employed as the adhesive layer between two complementary non-planar surfaces. Both wafer-level and chip-level bonding were carried out with an alignment tolerance of 5 μm. The bonding pairs exhibited enhanced tensile strength and shearing strength compared to that of the planar surface bonding, which was influenced by the gap between the bonding surfaces. This technology meets the requirements of the wafer-level three-dimensional structure transfer and opens up possibilities for manufacturing more complicated microelectromechanical systems devices.

Description: Three electromagnetic vibration energy scavengers with electroplated Ni springs have been designed, fabricated and characterised. Prototype I consists of a coil, an Ni spring on a silicon frame and a permanent magnet. Prototypes II and III are with a sandwich structure and consist of two coils, an Ni spring and a permanent magnet. There are air channels in the silicon frame in prototype III. These prototypes were fabricated using microelectromechanical systems microfabricating techniques. The experimental results show the electroplated Ni spring is a nonlinear and hardened one, so the spring–magnet system has a different resonant frequency under different excited vibration. The tested results show that prototype III has the highest output voltage and output power. The maximal load voltage is 157.5 mV and the maximal load power is 21.7 μW for prototype III when it is excited by vibration with 280.9 Hz frequency and 0.8 g acceleration.

Description: A micro plasma-nozzle device has been fabricated for plasma treatment for a single cell. The micro plasma-nozzle device consists of throughhole and trench structures. The nozzle device was attached to a guide tube (O.D.: Φ1.5 mm, I.D.: Φ1 mm) of an atmospheric pressure microplasma. Once plasma gas was supplied into the guide tube, most of the plasma gas was exhausted through trench structures, whereas the remaining plasma was excited through the nozzle hole. The nozzle device with Φ5 μm holes achieved minimum plasma irradiation onto a PDMS film. The plasma-modified area was Φ5.4–5.6 μm, which was much smaller than the area size modified by direct plasma irradiation from the guide tube (Φ3–4 mm). The plasma irradiation caused protrusions on the PDMS surface. The minimised plasma irradiation formed 170 nm-height-protrusion-structures on the PDMS surface. The plasma irradiation through the nozzle device was applied to an onion tissue using a nozzle device with Φ10 μm holes. The plasma irradiation formed Φ10–15 μm holes in the onion cell membrane.

Description: A microbial chip is demonstrated that immobilises microbes into micro holes using positive dielectrophoresis (DEP) for efficient screening. The DEP frequency was set at 10 MHz, which was found to be most effective to selectively immobilise live bacteria. The media including reactive agents can be flown into the chip continuously and therefore the reaction products can be continuously collected. Immobilisation of microbes enables quantification of the number of microbes involved in the reaction and makes their reactions conditions consistent. These advantages enable the proposed microbial chip to evaluate the production capacity of a single bacterium. To demonstrate it, the developed microbial chip was used to characterise microbes and evaluate biological activity. First, Corynebacterium bacterium was used as a sample bacteria. The chip successfully revealed the production capacity of lactic acid by a single C. bacterium. It was experimentally found that the production rate of lactic acid of Corynebacterium glutamicum increased 1.7 times and 3.8 times by adding pyruvic acid and sodium bicarbonate, respectively. Secondly, microbes belonging to the Corynebacterium group with respect to the lactic acid production were screened. Corynebacterium variabile was experimentally found to be the most productive among three tested members. The proposed microbial chip is readily applicable to an efficient microbial screening platform and potentially a reliable microbial sensor given the capacity of quantifying the total number of bacteria involved in the microbial reaction.

Description: Micro fabrication has been conducted for sodium potassium niobate [(K,Na)NbO 3 , KNN] thin films by dry etching and Pt/KNN/Pt unimorph micro cantilevers have been fabricated as a lead-free piezoelectric micro electro mechanical system (MEMS). KNN etching by Ar/C 4 F 8 plasma showed a high etching rate of about 60 nm/min and KNN/Cr selectivity of over 5. Tip displacement of the Pt/KNN/Pt micro cantilevers was measured and the frequency response and piezoelectric properties were evaluated. Young's modulus and piezoelectric coefficients d 31 of the KNN thin film were estimated to be 115 GPa and –99 to 219 pm/V, respectively. These results indicate that Ar/C 4 F 8 plasma etching does not degrade the piezoelectric properties of KNN thin films and enables one to fabricate various lead-free piezoelectric MEMS applications.

Description: A microsensor chip was fabricated by micro electromechanical system technology, and a portable electrochemical system for nitrate determination in freshwaters was developed. As the electrocatalyst material, copper was electrodeposited onto the working-electrode of the microsensor by the cyclic voltammetry method. It was found that the deposited layer was porous and constructed by copper nanoclusters. The electrochemical response of the modified microsensor for nitrate under acidic conditions (pH = 2.0) was characterised by linear sweep voltammetry. Calibration in standard nitrate samples in the range of 6.25–300 μmol/l yielded straight lines: y 1 [μA] = 20.0526x–3.905 (R 2 2 = 0.9993), while in the range of 300–3500 mmol/l yielded straight lines: y 2 [μA] = 20.0353x–13.653 (R 1 2 = 0.9918). It was found that the modified microsensor performed at higher sensitivity in nitrate detection than previous works and the limit of detection is 5 μmol/ l (S/N ⩾ 3). Interference analysis with nine kinds of ions (NO 2 - , Cl - , HPO 4 2- /PO 4 3- , SO 4 2- , HCO 3 - /CO 3 2- , Na + and K + ) commonly found in water indicated that only NO 2 - causes reasonable interference (i.e. 10% signal distortion). Based on the modified microsensor, the developed portable electrochemical system was employed for nitrate determination in three freshwater samples. The results were in good agreement with the data obtained by the ultraviolet spectrophotometric method.

Description: A new micro-machined resonant accelerometer with a differential structure enabling the detection of out-of-plane acceleration is described. The microaccelerometer consists of two sensitive structures composed of seismic masses, flexural hinges and double-clamped resonant beams. Owing to thickness differences and neutral axis variations among these three components, in response to an out-of-plane acceleration, the movements of the seismic masses lead to stress build up in flexural hinges, further translated as axial forces applied on resonant beams. In this differential design, under acceleration, one resonant beam is under a tensile stress, whereas the other one is under a compressive stress, producing a differential resonant frequency output. The microaccelerometer was fabricated by a silicon-direct-bonding silicon-on-insulator wafer with MEMS fabrication and a low-stress packaging method was also developed. Based on a closed-loop control circuit for resonant beam excitation and detection, device characterisation was conducted, producing a quality factor of 436 in air and a differential sensitivity of 813 Hz/g.

Description: Nanomechanical (NEMS) resonators made from carbon nanotubes (CNTs) have emerged as ubiquitous devices for use in mass detection. Many oscillation behaviours of CNT mass detection have been theoretically studied by the continuum elastic model, albeit their performance is limited by deleterious effects of mechanical damping. Reported are the support-induced losses in generic mechanical resonators because of the tunnelling of mesoscopic phonons between the CNT and its supports. After formulating the problem, the resulting differential equations are solved analytically using the method of multiple scales, and a closed form solution is obtained. The results reveal that the Young??s modulus, density and geometric parameters of the CNT not only influence the resonant frequency shift and the system stiffness, but also affect the system vibration amplitude. Moreover, the effect of the supports material on the oscillation is discussed. Also, the phonon-tunnelling dissipation for dynamics of CNT mass detection is highlighted.

Description: Presented is a method that can regulate the resonant frequency and the quality factor (Q-factor) of an electromagnetic vibrating ring gyroscope by electronic tuning. A novel circuit is designed to control the drive mode of the electromagnetic vibrating ring gyroscope. The circuit consists of an amplifier and a phase shifter used for feedback control. The frequency split can be reduced and the Q-factor can be improved through this method. Experimental results show that the frequency shift of the drive mode can be from –6.41 to 6.38 Hz when the phase of the feedback signal shifts ±90° compared with the drive signal. The Q-factor in the air can be improved from 522 to 821 when the phase of the feedback signal is not shifted. The sensitivity tests show the effectiveness of the control circuit.

Description: Aiming to meet the ever-increasing challenge of a low cost, portable and real-time sensitive detection polymerase chain reaction (PCR) system, a novel in situ electrochemical detection static micro PCR (EC-SμPCR) chip is designed and fabricated. The 10 x 10 mm EC-SμPCR chip comprises 12 micro reaction chambers, and each 1500 x 1000 x 60 μm chamber consists of three modules: a micro heater, a micro temperature sensor and a micro three-electrode system (MTES). Heating, cooling and electrochemical cyclic voltammetry (CV) experiments were carried out to investigate the performance characteristics of each module of the chamber in the EC-SμPCR chip. The results showed that the heating rate of the chip was 1.05°Cs –1 with only one micro heater, whereas the cooling rate was 1.01°Cs –1 with natural air cooling. It is worth noting that the bare MTES of the chamber directly detected the oxidation of single-stranded DNA (ssDNA, 10 –6 M) with the CV method, furthermore, the oxidation peak current of ssDNA can be increased about 40% after a prepolarisation step. All three modules of the chamber in the EC-SμPCR chip work efficiently and reliably, which reveals that the entire chip is ready for further analysis trials.

Description: Hollow poly(m-phenylenediamine) (PmPD) microparticles were successfully synthesised with chemically oxidative polymerisation through rapidly mixing the persulphate oxidant solution with m-phenylenediamine solution at room temperature. In a further experiment, Na 2 CO 3 was used to create a CO 2 bubble to facilitate the formation of hollow PmPD microparticles. The morphology and molecular structure of the products were characterised with scanning electron microscopy, transmission electron microscopy and Fourier transmission infrared spectroscopy. The results showed that the PmPD possesses a mouth-like cave when synthesised without Na 2 CO 3 . More interestingly, using Na 2 CO 3 , the cave number and shape of PmPD microparticles change. The PmPD synthesised with or without Na 2 CO 3 has similar functional groups but different oxidation state.

Description: Uniform rare-earth gadolinium oxide (Gd 2 O 3 ) hollow spheres with tunable shell thickness have been successfully fabricated in the presence of SiO 2 as templates via a urea-based homogeneous precipitation method. The synthesis is a mild, low-cost and convenient method without any catalysts. By varying the times of the precipitation procedure, the shell thickness can be successfully controlled within the 20–55 nm range. The thickness increase of each coating might be ~ 10 nm. The as-synthesised product was identified from X-ray diffraction pattern, scanning electron microscopy and energy dispersive X-ray. The prepared hollow Gd 2 O 3 spheres with tunable shell thickness and fluorescence property have the potential to be used for drug delivery, fluorescent labelling and controlled release applications.

Description: Metastable intermolecular composite (MIC) has been widely touted for their potential to fulfil the objectives of high energetic materials and nanotechnology. In this study, nanofibrous CuO/Al MIC films on the silicon substrate were successfully synthesised by evaporating and depositing Al on the surface of nanoporous CuO films, which were prepared by calcinating polyvinylpyrrolidone (PVP)/Cu(NO 3 ) 2 films obtained through the electrospinning process. The structures and energetic properties of the nanofibrous CuO/Al MIC films were characterised by a scanning electron microscope, X-ray diffraction, Fourier transform-infrared spectroscopy, TGA–DSC and open-air combustion experiments. The results revealed that the electrospinning process was an effective way to prepare energetic films. The optimised calcination temperature of the PVP/Cu(NO 3 ) 2 composite films was 500°C, and the starting reaction temperature of the nanoporous CuO/Al MIC film was 532°C.

Description: Through nanoindentation and nanoscratch tests, it is demonstrated that friction-induced protrusive nanostructures (or hillocks) showed good mechanical behaviour. At the maximum indentation depth of 2 nm, the elastic modulus of the hillocks on the silicon/quartz surface was only 5.3%/14.8% lower than that measured on their substrates. After scratching under a contact pressure of 10.3 GPa on silicon hillocks or 7.2 GPa on quartz hillocks, no surface damage was observed on the scratched area. Hence, the friction-induced hillocks can withstand typical contact in dynamic MEMS. Even though the scratch depths were much larger than the height of the detected hillocks, no peeling-off scar or surface crack could be detected beside the grooves on the hillocks, which indicated that the hillocks bonded strongly to their substrates. Further analysis revealed that the strength of the friction-induced hillocks was strongly dependent on the friction-induced process. The hillock produced at high sliding speed can lead to a high elastic modulus. Transmission electron microscope detection showed that the deformed silicon matrix formed chiefly at high sliding speed can enhance the elastic modulus of the hillocks. As a comparison, the amorphous silicon layer formed mainly at low sliding speed can reduce the elastic modulus of the hillocks.

Description: A report is presented on a novel and effective route to synthesise bismuth nanoparticles (BiNPs) on the electrode surface, which was carried out by ion-exchange in Nafion film coated on the electrode surface and subsequent electrochemical reduction of Bi 3+ ions to BiNPs on site. The properties of the resulting BiNPs modified electrode were investigated by scanning electron microscopy, an energy dispersive X-ray microanalyser and electrochemistry. Almost 10 nm BiNPs were decorated in the matrix of Nafion film and showed excellent electrochemical activity. The BiNPs modified electrode has been successfully used for determination of Pb 2+ by anodic stripping voltammetry with a linear range of 1.0–90 nM. The detection limit is 0.3 nM with 5 min accumulation. The practical application of this modified electrode was carried out for determination of Pb 2+ in water samples and the results were consistent with those obtained by inductively coupled plasma-mass spectrometry.

Description: High aspect ratio iridium (IV) oxide nanorods have been successfully grown on a copper thin film by a chemical co-precipitation method. A porous anodised aluminium oxide (AAO) template was implemented to assist the growth of the well aligned and densely packed iridium oxide ( IrO 2 ) nanostructures. Nanorods with an aspect ratio of 22 can be synthesised within 45 min. X-ray diffraction measurement unveiled the crucial role of the AAO template in the orientation-aligned growth of IrO 2 nanorods along the [110] crystallography direction. The large surface area of IrO 2 nanostructures exhibiting a high capacitive property can be utilised in supercapacitors or sensing applications. Owing to the simpler fabrication processes, IrO 2 nanorods can be mass produced in a short period of time.

Description: An atomic force microscopy (AFM) image of a surface is a convolution of the tip geometry and sample features. It is important to develop tip characterisers and estimate the tip shape for a more accurate AFM image. With the traditional characterisers with special microstructures it is difficult to accurately determine tip shape because of their dimensional uncertainty. Combined with tip blind reconstruction algorithms, some nanomaterials with arrayed nanostructures are often used to estimate the AFM tip morphology. However, the blind reconstruction algorithms are sensitive to image noise. To solve such problems, the porous anodic alumina (PAA) film with well-ordered porous nanostructures was fabricated and used as a new tip characteriser. By setting the appropriate scanning routine and scanning mode, the two-dimensional and three-dimensional tip morphology was accurately calculated. PAA film as the AFM tip characteriser can effectively reduce the influence of AFM image noise and sample-dimensional uncertainty of tip blind estimation results, especially avoiding tip wear and damage.

Description: Rod-like nanosized silver tungstate (Ag 2 WO 4 ) was synthesised via a facile hydrothermal method and characterised by field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and electron spin resonance spectroscopy. Under ultraviolet (UV) light, nearly complete degradation of rhodamine B (RhB) was observed in Ag 2 WO 4 suspension after irradiation for 60 min, around 15% RhB was absorbed in the dark. However, more than 60% of methyl blue was absorbed in the dark and the rest was observed to be completely degraded upon UV light irradiation for 10 min. The formed superoxide (O 2 - ) and hydroxyl (·OH) radicals, as well as photoinduced holes were considered to be the dominant active species in the photocatalytic process.

Description: Quantum dots (QDs) as new fluorescent nanomaterial, have shown potential application for in vivo imaging technology in the past decades, whereas the toxicity of QDs hinders the development of this technology for in vivo application. Here, the authors report a facile, rapid and reproducible route to synthesise protein conjugated CdSe QDs by microwave irradiation. Ribonuclease A protein could serve as a bio-molecular template in the formation of CdSe clusters, and it endows the CdSe QDs with high stability and low bio-toxicity in aqueous medium. The final products were characterised by UV–vis absorption, photoluminescence spectra, X-ray powder diffraction and high-resolution transmission electron microscopy. Furthermore, MTT assay has shown that it has high biocompatibility and low toxicity in vitro.

Description: In this study, an amino acid, glutamine, has been employed as the modifier in the hydrothermal synthesis of rod-like hydroxyapatite (HAp) nanoparticles. X-ray diffractometer results confirm the formation of a typical HAp phase without impurities and microscopic results indicate that the morphology and size of the as-prepared products could be controlled by adjusting the pH value of the hydrothermal system. Owing to a variety of amino acids and characteristics of as-synthesised nano-sized HAp, the findings may have implications in the large-scale controllable synthesis of well-defined HAp nanomaterials; it may also provide a general facile and low-cost method for the preparation of uniform nanostructured HAp by utilising biomolecules as modifiers.

Description: A G-band microelectromechanical system (MEMS) rectangular waveguide iris filter is designed and fabricated. The effects of the metallised layer and iris thickness, and roughness, on filter main performances are investigated. The prototypes were fabricated using MEMS manufacturing techniques. The key technique problems including deep etching, electroplating and bonding are researched and settled. The measured insertion loss can get to be 1.5–2.0 dB, the central frequency is 174 GHz, the bandwidth is 9.6 GHz, and the isolation out of the bandpass is larger than 15 dB. The test results show that the radio frequency MEMS filter meets practical requirements, which proves that it is a successful example for fabricating such rectangular waveguide devices at one to several hundred gigahertz frequencies using such presented processes.

Description: Polypyrrole-coated Li 2 SnO 3 ( Li 2 SnO 3 /PPy) nanocomposite has been prepared by a micro emulsion polymerisation. The X-ray diffraction and transmission electron microscopy analysis reveals that the Li 2 SnO 3 crystal particles with a uniform and block structure are coated by PPy with amorphous behaviour. The particle sizes of Li 2 SnO 3 are in the range from 40 to 50 nm with clear lattice fringes. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis reveals the surface structure and the binding nature of the elements of Li 2 SnO 3 / PPy composite. Electrochemical measurement suggests that Li 2 SnO 3 /PPy nanocomposite exhibits better cycling properties and lower initial irreversible capacities than Li 2 SnO 3 as anode materials for lithium-ion batteries. At a current density of 60 mA/g in the voltage about 0.01– 2.0 V, the first discharge–charge capacities of Li 2 SnO 3 /PPy are 1482.2 and 892.1 mAh/g, whereas they are 2104.5 and 1417.0 mAh/g for Li 2 SnO 3 . The retention capacity of Li 2 SnO 3 /PPy (560.1 mAh/g) is higher than that of Li 2 SnO 3 (510.2 mAh/g) after 50 cycles.

Description: Electrodeposition of copper in cylindrical pores of a nanoporous alumina template is investigated. An electrochemical deposition mode with pulsed current is used in an aqueous copper sulphate solution. The evolution of the deposition quality in terms of height, shape and filling ratio is analysed against several parameters: the intensity, duration and number of pulses. Systematic observations and analyses using scanning electron microscopy are carried out. Statistical and quantitative treatment has been performed. A high filling ratio of more than 90%, the height control and a conformal shape of the copper nanoparticles have been achieved.

Description: Biological adhesive pads of some reptiles and insects, such as tree frogs and grasshoppers, are covered with planar microstructures and have strong and stable adhesive ability on both wet and dry substrates. These adhesion forces do not mainly come from van-der-Waals force but wet adhesion. In this study, the influence of substrates' surface roughness on the wet adhesion of man-made adhesive pads inspired by tree frog toe pads is investigated experimentally. Biomimetic polydimethylsiloxane adhesive pads with planar hexagon microstructures with a microchannels width of 10 μm are fabricated by combining electroforming with soft lithography. Experiments of wet adhesive force between the pads and sandpaper slices with different average surface roughness are carried out at various preloads. Results show that the rougher surface leads to the decrement of wet adhesion force. It is also observed that if the microcosmic profile height of the substrates is near or less than the width of microchannels in the biomimetic adhesive pads, the microstructures and preloads can increase significantly the wet adhesive force, otherwise the microstructures and preloads do not contribute indistinctively. The experimental results can be explained by analysing the relation between the solid contact area and the area with a liquid bridge.

Description: A report is presented on the synthesis of gold nanoparticles (AuNPs) using aqueous extract of Sapindus mukorossi, a traditional medicinal plant in India. UV-visible spectroscopy analysis indicated the successful formation of AuNPs. The synthesised AuNPs were characterised with different techniques such as transmission electron microscopy (TEM), Fourier transforms infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX). TEM experiments showed that AuNPs were predominantly spherical and hexagonal in shape with an average size of 7.3 nm. FTIR spectroscopy revealed that AuNPs were functionalised with biomolecules that have primary amine group (–NH2), carbonyl group, –OH groups and other stabilising functional groups. Thermo gravimetric analysis (TGA) revealed the weight loss (13%) of AuNPs. FTIR, TGA and EDX together confirmed the presence of biomolecules bounded on the AuNPs. Cytotoxicity of the AuNPs was tested on two human cancer cell lines, HeLa and A549 and found to be non-toxic, which thus proved their biocompatibility.

Description: Metal microneedles are fabricated by the process of cutting and electrochemical corrosion. The fabricated microneedles are 400 μm in length, 700 μm in space and have sharp tapered tips. In a force test, these microneedles could penetrate an artificial skin and a rat??s skin well and safely. In a vitro transdermal drug delivery test, the amount of the permeated flux of calcein and of the bovine serum albumin through the treated rat skin increased by 35 and six times than that on the intact skin, respectively.

Description: Oriented gallium nitride (GaN) nanowires grown on Pt-coated Si (1 1 1) substrates, were synthesised using the chemical vapour deposition method under different Ga sources. The characteristics of the grown GaN nanowires were investigated using scanning electron microscopy and X-ray diffraction, which found that the as-synthesised GaN nanowires of the three samples are of different orientation, and all displayed hexagonal wurtzite structures of GaN crystals. The electron field-emission properties of the three samples of GaN nanowires showed a low turn-on field of 4.5, 5.5 and 6.2 V/μm, respectively, and field enhancement factors of 1337, 2948 and 2599, respectively.

Description: A convenient sonochemical process for the preparation of HgSe nanoparticles by using Hg(CH 3 COO) 2 and SeCl 4 in the presence of hydrazine as reductant agent has been discovered. Three capping agents have been used that include triethanolamine, sodium dodecyl sulfate and thioglycolic acid. The products were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy (PL) and X-ray energy dispersive spectroscopy. The effects of the capping agent, ultrasonic power, temperature and reaction time on the morphology, particle size and phase of nano-sized HgSe products have been investigated. HgSe microspheres are obtained after 15 min of sonocation. With increasing aging time, the microspheres were broken and agglomerated nanoparticles are formed. With increasing temperature smaller sizes of HgSe are obtained. The particles coalesce and turn into bulk structures in the absence of sonocation. The as-prepared HgSe shows a blue-shifted emission in the PL spectrum, compared with the bulk sample, which confirms the larger variation of particle sizes.

Description: The cube and hexagonal prism zinc oxide (ZnO) microstructures have been controllably synthesised by the facile liquid precipitation method by using sodium dodecyl benzene sulphonate and cetyltrimethyl ammonium bromide as surfactant separately. The probable formation mechanism is also proposed based on the experimental results. The photoluminescence characterisation of cube and hexagonal prism ZnO structures exhibited a strong blue emission at 470 nm and the emission intensity of the cube ZnO improved ~60% more than the hexagonal prism ZnO. The photocatalytic activities of the cube and hexagonal prism ZnO were investigated by methyl orange, rhodamine B and fuchsine acid as a model organic compound under ultraviolet light irradiation. The results show that the photocatalytic activity of the cube ZnO is superior to that of the hexagonal prism ZnO when the above three dyes were used. It is suggested that photocatalytic activities are improved by changing the morphologies of ZnO crystals.

Description: The vibration behaviour of a simply supported carbon nanotube is studied using the non-local viscoelasticity theory, including the thermal and foundation effects. The complex frequency in closed-form expression is obtained in terms of the damping ratio. The frequency is associated with the non-local parameter, damping coefficient and thermal and foundation effects. According to the analysis, the natural frequency significantly decreases by increasing the damping coefficient, especially at a small non-local parameter. The critical damping coefficient decreases when the thermal effect is considered in the analysis, especially at a higher non-local parameter. However, the situation is reversed when the foundation effect is considered. In addition, by increasing the non-local parameter, the mode shape increases. However, the mode shape apparently decreases by increasing the damping coefficient.

Description: A report is presented on the structural, electrical, optical and magnetic properties of Fe-doped ZnO nanoparticles synthesised by the solution combustion technique. Structural characterisation by X-ray diffraction confirmed the phase purity of the samples. Surface morphology studied by scanning electron microscope revealed a cubic-type shape of grains. Energy dispersive X-ray spectroscopy analysis confirmed the elemental composition. Less value of DC electrical conductivity and increased bandgap for doped ZnO from UV–Vis studies confirmed change in the defect chemistry of the ZnO matrix. However, varied synthesis process results in ferromagnetic behaviour for doped ZnO nanoparticles.

Description: Polymer-based nano/microfluidic devices are becoming increasingly important for biological applications and fluidic control. Reported is a new etching method for the fabrication of nano/microfluidic channels based on SU-8 using AZ1350 as a sacrificial resist. In contrast to all the previous fabrication routes, this etching method is suitable for fabricating the channel with dimensions ranging from micrometres to nanometres. By this route, the most critical step is to prevent the two mixed photoresists and this problem is solved by sputtering a thin layer of SiO 2 . Furthermore, this is a size-controlled nanochannel fabrication method because the size of the channel is only dependent on the sacrificial layer structure whose size could be controlled by the oxygen plasma process. In addition, the developing etching speed is measured and some methods to accelerate the developing etching rate are proposed. This novel process is simple and inexpensive for mass nano/microchannel manufacturing, which could have wide applications in biomedical and fluidic transport systems.

Description: Ni–Ce 0.8 Gd 0.2 O 1.9 composite is an efficient anode electrode in solid oxide fuel cells. In this study, for the first time, the remarkably simple technique of electrospinning has been employed to prepare the corresponding nanofibres. For this purpose, the cation complexation method was applied for preparing a sol containing Ni, Gd and Ce nitrates as the precursors and citric acid as the chelating agent. Gel formation was accomplished by heating the sol at 80°C and then a polyvinyl alcohol solution was added to maintain proper viscosity of the electrospinning solution. The spun nanofibres were calcined at different temperatures to obtain the NiO-GDC nanofibrous material. Calcined nanofibres were characterised by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, a energy dispersive spectrometer, transmission electron microscopy and Brunauer-Emmett-Teller techniques. It was found that the size of crystalline nanofibres were in the range of 90 nm. Specific surface area is found to be 145 m 2 /g for the calcined nanofibre at 900°C.

Description: The amorphous NdCo x O y nanowire arrays have been successfully fabricated using anodic aluminium oxide (AAO) membrane templates by suction filtration at subatmospheric pressure (SFSP). The morphology and chemical composition of NdCo x O y nanowires were characterised by a scanning electron microscope, a transmission electron microscope, selected area electron diffraction, X-ray diffraction and energy dispersive spectra, respectively. The results reveal that there are plenty of NdCo x O y nanowires in the nanopores of the AAO template, and the NdCo x O y nanowires are all uniform in diameter. The concentration of reactants, the subatmospheric pressure and the co-precipitation time played an important role in the formation of NdCo x O y nanowires. The NdCo x O y nanowires with different diameters were fabricated with AAO of different nanopore sizes, the luminescence spectrum of NdCo x O y nanowires were doped with different Eu 3+ concentrations and different morphological luminescence intensities of NdCo x O y :Eu 3+ indicate that the method of SFSP is a feasible and controllable approach. The hysteresis loops of the Nd 2 O 3 , NdCo x O y and NdLa x O y nanowire arrays were carried out by a vibrating sample magnetometer (VSM); the magnetic behaviour of rare earth oxide can be modulated by doping the magnetic cobalt (Co) and non-magnetic Lanthanum (La) elements.

Description: Presented is a method for aspirating liquids into a hollow atomic force microscope (AFM)-cantilever through a 350 nm-wide nozzle near the tip apex. The cantilever was made of transparent SiO2 and connected a fluidic reservoir to an evaporation cell. The nanopipette-chip is suitable for mounting the microfluidic system into commercial AFMs. The channel inside the lever spontaneously filled with liquid by capillary forces upon which evaporation started and continuously pumped liquid from the reservoir. The resonance frequency of the cantilever was found to be 153.946 kHz when empty and a frequency shift of 92 Hz was measured when filled. The cantilever's transparency allowed visualisation of the advancing meniscus in real time and confirmed the presence of aspirated, fluorescently labelled liquid. An aspiration rate of ˜230 aL/s was measured. This value represents the flow rate in the microfluidic system when operated under ambient conditions (21°C temperature, 43% relative humidity). The estimated volume that has been aspirated in total was ˜ 85.42 aL. The aspiration capability of the device was tested and analysed under an optical microscope using an aqueous solution of fluorescently labelled nanobeads. The nanopipetting experiments represent an extension over the authors' earlier work which concentrated on the dispensing and imaging capabilities of a similar system.

Description: The HKUST-1 metal-organic framework (MOF) was selected because of the large internal surface area, excellent stability and known properties. Mechanical strain is generated upon the adsorption of analytes into the MOF; it is proportional to concentration and is a function of adsorbed species. Piezoresistive microcantilevers serve as a transduction mechanism to convert surface strain into electrical signals. N-doped piezoresistive cantilever arrays were fabricated with ten structures per die. Thin films of HKUST-1 were grown at room temperature using layer-by-layer techniques. Dry nitrogen was used as a carrier gas to expose devices to varying concentrations of 12 different volatile organic compounds (VOCs). Results show that stress-induced piezoresistive microcantilever array sensors with MOF coatings can provide a highly sensitive and reversible sensing mechanism for water vapour and methanol. Characteristic response features allow discrimination based on shape, response time constants and magnitude of response for other VOCs. Devices provided reliable data and proved durable over 18 months of testing. The key advantages of this type of sensor are higher sensitivity with a microporous MOFs, reversible response, α single chip sensing system and low power operation.

Description: Demands to improve the sensitivity and measurement speed of dynamic scanning force microscopy and cantilever sensing applications necessitate the development of smaller cantilever sensors. As a result, methods to directly drive cantilevers, such as photothermal or magnetic excitation, are gaining in importance. Presented is a report on the effect of photothermal excitation of microcantilevers on the increase in steady-state temperature and the dynamics of higher mode vibrations. First, the local temperature increase upon continuous irradiation with laser light at different positions along the cantilever was measured and compared with finite element analysis data. The temperature increase was highest when the heating laser was positioned at the free end of the cantilever. Next, the laser intensity was modulated to drive higher flexural modes to resonance. The dependence of the cantilever dynamics on the excitation laser position was assessed and was in good agreement with the analytical expressions. An optimal position to simultaneously excite all flexural modes of vibration with negligible heating was found at the clamped end of the cantilever. The reports findings are essential for optimisation of the excitation efficiency to minimise the rise in temperature and avoid damaging delicate samples or functionalisation layers.

Description: A mathematical model is developed for the burning of a single nanosized aluminium particle in air. First, based on thermal definition, the ignition temperature of single Al is obtained. For this purpose, the interpolation method is used for the conduction of heat loss rate in the transition regime; the chemical heat generation rate is described by a single term Arrhenius ignition model; the Gibbs-Thomson equation for an isolated spherical solid particle is utilised for modelling the size dependent melting temperature of nanoparticles; and the size dependent activation energy is also obtained. The theoretical result shows that the ignition temperature is slightly higher than the melting temperature. With the assumption of constant particle size and the use of the 'Taffanel and le Floch' condition, the burning time of a single aluminium particle is achieved. According to the obtained results, as particle size decreases or pressure increases, the reaction rate increases.

Description: A functional layered nanocomposite, MB + -Ca 2 Nb 3 O 10 , was prepared by the intercalation of methylene blue (MB) into the layered material, KCa 2 Nb 3 O 10 , by a guest-exchange method using the n-PrNH + 3 -Ca 2 Nb 3 o 10 intercalation compound as an intermediate. The resultant nanocomposite was characterised by powder X-ray diffraction and infrared. Electrochemical studies reveal that the target hybrid retains the good redox activities of MB + cation and has potential utilisation in electrocatalytic reactions.

Description: N-doped SiO 2 at TiO 2 core-shell structural materials has been synthesised successfully via a simple two-step method. First, SiO 2 spheres were obtained by using a slightly modified St??ber process. Then, N-doped SiO 2 at TiO 2 were prepared via coating SiO 2 template with TiO 2 layers, followed by N-doping using NH 4 NO 3 as the N source. According to Kato et al. the as-obtained products were well characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and UV??vis absorption spectra. The photocatalytic activity of the as-prepared products was evaluated by photocatalytic decolourisation of rhodamine B aqueous solution at ambient temperature under UV and visible-light irradiation. The experimental results showed that the diameter of N-doped SiO 2 at TiO 2 spheres was about 250 nm and the thickness of the TiO 2 shell was 10-20 nm, the products exhibited a high photocatalytic activity because N atoms were incorporated into the titanium dioxide planes to decrease the bandgap energy.

Description: The objective of the present reported study was to evaluate the oral toxicity of poly (lactic acid)-b-Pluronic-b-poly (lactic acid) (PLA-P85-PLA) nanoparticles (NPs) so as to demonstrate their applicability for drug delivery applications. In acute oral toxicity studies, the animals were fed with 0.4 ml PLA-P85-PLA NPs solution in different concentrations (low concentration: 20 mg/l, intermediate concentration: 100 mg/l and higher concentration: 500 mg/l) for 14 days; no deaths or treatment related complications were observed even in the higher concentration treatment. In case of the subacute oral toxicity test, the NPs were administered orally to mice for a period of 28 days. At the end of the study, blood samples were collected for biochemical analysis. For histopathological analysis, organs of the animals were weighed and processed. All the animals survived during the study, with no significant changes in clinical signs, body weight, feed consumption, biochemistry parameters, organ weights and histopathological findings. These results demonstrate that PLA-P85-PLA NPs produced no treatment related toxicity in mice following oral administration, thus, they can be exploited for potential therapeutic applications.

Description: The realisation of special anisotropic sliding behaviour of liquids on metal substrates is very important for applications in fluidic control and water directional transportation. Proposed is a method combining lithography assisted electrochemical etching, anodic oxidation and fluoridation to construct the three-level microstructures (macro/micro/nano) of rice leaves on aluminium. Similar to the natural rice leaf, the prepared surface was endowed with multiple-level microstructures and exhibits superhydrophobicity. The measurements show the biomimetic rice-leaf surface has different anisotropic sliding behaviour with water droplets of different volumes. The perpendicular and parallel sliding angles (SAs) of a 4 μl water droplet were 6.8° and 2.7°, respectively, the anisotropy was 4.1°, which is comparable to that of a natural rice leaf. A mathematical model is presented to explain the mutational significant anisotropy of SAs (10.2°) when the water droplet was only 2 μl. This method is simple and economical, and is believed can be used for the fabrication of large-area biomimetic rice-leaf surfaces on metal.

Description: Recent experimental and analytical research has shown that higher in-fluid quality factors (Q) are achieved by actuating microcantilevers in the lateral flexural mode, especially for microcantilevers having larger width-to-length ratios. However, experimental results show that for these geometries the resonant characteristics predicted by the existing analytical models differ from the measurements. A recently developed analytical model to more accurately predict the resonant behaviour of these devices in viscous fluids is described. The model incorporates viscous fluid effects via a Stokes-type fluid resistance assumption and 'Timoshenko beam' effects (shear deformation and rotatory inertia). Unlike predictions based on Euler-Bernoulli beam theory, the new theoretical results for both resonant frequency and Q exhibit the same trends as seen in the experimental data for in-water measurements as the beam slenderness decreases. An analytical formula for Q is also presented to explicitly illustrate how Q depends on beam geometry and on beam and fluid properties. Beam thickness effects are also examined and indicate that the analytical results yields good numerical estimates of Q for the thinner (5 μm) specimens tested, but overestimate Q for the thicker (20 μm) specimens, thus suggesting that a more accurate fluid resistance model should be introduced in the future for the latter case.

Description: In this reported work, superfine silver nanoparticles were synthesised from silver nitrate through a simple, rapid and eco-friendly route applying tangerine extract, which acts as a solvent, reducing agent and stabilising agent simultaneously. The appearance of a darkish brown colour solution is indicative of silver nanoparticles that were confirmed by a UV-vis spectrophotometer. The as-prepared sample was further characterised using X-ray diffraction and energy dispersive X-ray analysis analyses. The morphology and size of the nanoparticles were characterised by scanning electron microscopy and transmission electron microscopy. The silver salt exposing the tangerine extract is reduced and stabilised over long periods of time that results in the green synthesis of silver nanoparticles. The produced nanoparticles were stable over a long period of time and appropriate for applications in biotechnology.

Description: Described is an approach to fabricate bulk nanoporous silver with a diameter of 12 mm and thickness of 5.4 mm via dealloying Ag 25 Zn 75 alloy in 0.1 mol/l sulphuric acid at 0.4 V for 100 h at room temperature. The volume of the bulk nanoporous contracts 14.2% compared with the starting alloy. Meanwhile, crystal structure switches from close-packed hexagonal to face-centred cubic, which can be considered as a type of phase transition during dealloying. An intrinsically inhomogeneous morphology in microscale exists in bulk nanoporous silver by dealloying, which is caused by coarsening of the ligament width via surface diffusion of silver atoms in the electrolyte for different times. Moreover, parallel orientation structures and cracks have been found in the specimen, which could be related to the columnar crystal of starting alloy during solidification. The lattice defects such as stacking faults, lattice distortions and twins can be seen in the ligaments.

Description: A novel sensor that deploys opto- and electrochemical techniques for the rapid and highly sensitive separation and detection of metal ions in aqueous media is reported. The sensor comprises a porous membrane coated with an ultra-thin porous layer of highly ordered, hexagonally packed arrays of metal (Au and Pt) nanoparticles with ⩽ 25 nm sub-gaps. This platform enables an integrated detection method that relies on in-situ surface enhanced Raman scattering. An additional scheme is utilised based on electrochemical impedance spectroscopy to increase both the selectivity and the sensitivity of the sensor. Electrochemical separation bolsters the effectiveness of the optical method through ion separation and pre-concentration. The latter are induced by forcing the liquid electrolyte through the membrane's nanopores through a new proposed method based on surface tension mismatch. The sensor demonstrates high selectivity for six different heavy metal ions (Hg 2+ , Cd 2+ , Pb 2+ , Cu 2+ , Co 2+ , Ni 2+ ) at concentrations that range from 1 to 20 ppb (1 ?? 10 -3 -20 ?? 10 -3 μg/ml). The novelty of this sensor consists of the fact that the separation, pre-concentration and detection of the targeted ions are all performed in a single stage, eliminating the need for time-consuming and complex sample preparation steps.

Description: Beautiful monoclinic bismuth vanadate (BiVO 4 ) microspheres have been fabricated by using the sodium dodecyl sulphate (SDS) assisted hydrothermal strategy with bismuth nitrate and ammonium metavanadate as a metal source. The physicochemical properties of the materials were characterised by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer- Emmett-Teller and UV-vis techniques. The photocatalytic activities of the as-fabricated BiVO 4 microspheres were measured for the photodegradation of methylene blue under visible-light irradiation. The effects of SDS on the synthesis of BiVO 4 microspheres were investigated. Comparison experiments were conducted and showed that the amount of SDS significantly influences the morphology of the products. The possible formation mechanism of such BiVO 4 microsphere material is also discussed.

Description: A modified couple stress theory is used to analyse the dynamic displacement of an atomic force microscope (AFM) cantilever during nanomachining. According to the analysis, the results show that the effect of size-dependence on the vibration behaviour of the AFM cantilever is obvious. The displacement obtained based on the modified couple stress theory is lower than that based on the classical beam theory. The maximum displacement of nanomachining with the AFM cantilever represents the cutting depth. When the excitation frequency is closer to the natural frequency of the cantilever, a larger material removal rate is obtained.

Description: The graphene nanoribbon (GNR) field effect transistor is one of the most competitive candidates for beyond-CMOS nanoelectronics because of the special electric characteristics of graphene. During graphene preparation, vacancy defects are inevitably introduced and affect transistor performances. In this Letter, four typical vacancy defects in GNR (i.e. single vacancy, divacancy, Stone-Wales and 555 777 defects) are examined. By quantum-mechanics-based simulation, the effects of these four defects on the energy band of the GNR are analysed. Moreover, their effects on the performances of the GNR field effect transistor, such as transmission coefficient and transfer characteristics, are studied and compared for various defect locations in the channel.

Description: In this reported work, comparison is made of a passivation treatment of a III??V compound semiconductor using ammonia and ammonium sulphide solution. The treatment is applied on In 0.53 Ga 0.47 As which is chosen for its high mobility especially in high electron mobility transistors. The samples were treated with various parameters such as precursor, vacuum condition and different chemical solutions. Then, samples were deposited with the high k-dielectric Al 2 O 3 (4 nm thickness) using the atomic layer deposition technique. Five different passivation treatments were used to give proper comparison. Native oxide elements and contaminants were inspected at the interface of the oxide layer and the substrate using X-ray photospectrometry in different angles (25° and 70°). The results indicate the effectiveness of some treatments to eliminate the oxide of gallium and arsenic with a slight presence of indium oxide.

Description: A ZnO/CdS composite with flower-like morphology was fabricated by combining a solvothermal route with a homogeneous precipitation process. The material characterisation showed that the composite was composed of hexagonal ZnO flowers and cubic CdS nanoparticles, and CdS nanoparticles were observed to assemble on the surface of the ZnO flowers. The presence of CdS nanoparticles on the surface of ZnO flowers resulted in a blue shift of characteristic peaks and decreasing of the photoluminescence intensity when compared with the ZnO flowers. Furthermore, the adsorption or photocatalytic degradation experiments indicated that the as-prepared ZnO/CdS composite exhibited superior adsorption or photocatalytic degradation activities for some organic dyes, such as methyl orange, rhodamine B, safranine T and methylene blue, which may be related to the modification of the CdS nanoparticles.

Description: The influence of total gas flow on the growth of carbon nanotube (CNT) forests in water-assisted chemical vapour deposition has been investigated. It was found that the average height of the CNT forests decreased gradually from 996.53 to 696.8 μm, and the growth yield decreased notably from 2.91 to 1.98 mg/cm 2 as the total flow increased, but the crystallinity and thermostability of CNT forests increased with increasing total flow. Investigation on CNT growth kinetics suggested that increasing the total flow could decrease the growth rate and shorten catalyst lifetime because of decreased gas dwell time and enhanced subsurface diffusion of Fe catalyst.