Heterostructures that are formed by incorporating one-dimensional (1D) titanium dioxide (TiO₂) nanobelts into 2D bismuth vanadate (BiVO₄) nanosheets are fabricated via an electrostatic self-assembly process. The key features are investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller, zeta potential, ultraviolet–visible (vis) diffuse reflection spectra and photoluminescence spectra. As vis-light sensitiser and catalyst support, 2D BiVO₄ nanosheets can improve the vis-light photocatalytic activity of 1D TiO₂ nanobelts. Results show that 1D TiO₂ nanobelt–2D BiVO₄ nanosheet composites exhibit more efficient decomposition rate of rhodamine B compared with pure TiO₂ nanobelts. The photocatalytic activity of TiO₂–5% BiVO₄ composites is nearly 1.7 times higher than that of pure TiO₂ nanobelts. The enhanced photocatalytic performance is attributed to the bandgap match and the formation of heterostructures between TiO₂ nanobelts and BiVO₄ nanosheets. The heterostructures extend the light responsive range and promote efficient separation of photoinduced electron–hole pairs.

The surface nanostructure evolution of as-cast AZ31B magnesium alloy subjected to ultrasonic impacting and rolling process was investigated. Results show that deformation twinning greatly emerges in early stage to coordinate with deformation. As strain increases, interactions between twin and dislocation and dislocation itself occur. Dynamic recrystallisation is induced with nucleation sites originating from grain boundary intersections with serious dislocation pile-up. Larger β-particles serve as nucleation sites of dislocation sources and small-sized substructures. With further refinement, β-particles get smaller and unevenly distributed, yet a number of particles approximately locating in line can still intercept dislocations, making them turn into sub-boundaries. The final grains with high angle boundaries are refined to 150–200 nm compared with the initial size of ∼500 μm.

To improve the thermal properties of novolac resin, zirconium diboride (ZrB₂) nanoparticles (ZNP) with different weight percentages (0, 2, 4 and 7) were introduced into novolac resin. ZrB₂ nanoparticles modified carbon–novolac (C–N) composites were used to determine and compare the ablation performance, thermal stresses and cracks, and mechanical properties of these modified polymer composites. Thermal protection via ablation was achieved through a self-regulating heat and mass transfer process involving an insulator with low thermal conductivity and concomitant formation of a hard char on the insulator surface after 160 s exposure to the combustion environment. Anti-oxidation mechanisms for the novolac resin modified with nanoparticles at different weight percentage were compared and discussed. Ablation performance shows a steady increase with the filler content until a maximum, at 4 wt% of ZNP, and then it decreases.

A simple chemical edge doping method to prepare the Ag nanoparticles/graphite nanosheets (Ag/GNS) composite is presented. The GNS were fabricated in water with the assistance of a high pressure homogenisation (HPH). Ag nanoparticles (Ag-NPs) were decorated on GNS by edge doping. HPH was proved to be an efficient way to fabricate GNS with active sites to anchor metal nanoparticles in the authors’ work. The Ag/GNS composite synthesised by edge doping barely had any defects. The average diameter of the Ag-NPs in this case was 52.6 nm. It was observed that the fabricated Ag-NPs distributed mainly on the edge of GNS where the active sites were. The Ag/GNS composite exhibited a distinct surface-enhanced Raman scattering effect with a low concentration of silver. The Ag-NPs on the composite had improved stability (up to a month). It is believed that this simple and green method of nanocomposite preparation will shed some lights on the large-scale production of metal-nanoparticles-decorated carbon matrices.

Optical response of the indium arsenide (InAs)/gallium arsenide (GaAs) quantum dots (QDs) with a bimodal distribution is investigated through varying an initial GaAs capping layer between 35 and 18 monolayers. Photoluminescence (PL) measurements confirm that a thinner initial capping layer can reduce the QD dimensions and also modify the population ratio between the large QDs and the small QDs. Therefore, PL quenching related to QD dimension and carrier transfer between the bimodal QD populations has been affected. Manipulation of the initial GaAs capping layer provides a feasible approach to tailor the formation and optical performance of InAs QDs for optoelectronic device applications.

Nanosheets of graphene oxide (GO) were incorporated into natural rubber (NR) to investigate the influence of the partial substitution for carbon black (CB) with GO on the crosslink structure and properties of NR composites. The results show that the dispersion of the fillers was improved by a few GO nanosheets instead of CB. The dynamic and static mechanical properties were improved by using a few GO nanosheets worth of substitution content. The NR/CB/GO (NG) composites show the lowest heat buildup value when the load of nanosheets is 1 phr, which corresponds to only 9°C. However, the comprehensive performance of the composites was poor, or even deteriorated, as the GO tended to aggregate due to the high concentrations.

DNA-based circuits are considered as the possible replacement for the traditional silicon transistor based circuits for biomedical applications, especially for implantable medical devices because of their programmability, bio-compatibility, light weight, and small size. The seesaw DNA circuits, which uses DNA strand displacement operation lacks the logic inversion operation and uses a dual-rail design to overcome this issue. Here, a logic inverter gate using DNA strand displacement operations is introduced. This logic inverter gate is having a modular property and hence it can be used anywhere in the circuit. A gate enabling technique is used to achieve the modular design and the same can be used in analogue designs also. A full-adder circuit is developed to confirm the modularity property of the logic inverter gate. The DNA circuits were simulated in visual DSD software.

Despite the current interest in microbial methods for the detoxification of effluents, relatively little work has focused on the characterisation of metal uptake by small Aspergillus niger spores, particularly for heavy metals present at different and low concentrations. The objective of this study was to determine the ability of A. niger spores (free spores and as immobilised biosorbent) to remove toxic metals from an industrial wastewater as a batch system. The simultaneous influences of the mass of pH and biomass on the ability of spores to uptake of Cr(VI) were analysed. The free and immobilised biosorbent removed Cr(VI) efficiently with a maximum metal removal capacity of 55 and 40 mg/g, respectively. The biosorption mechanism was also investigated using Fourier transfer infrared and scanning electron microscopy. Immobilised spores of A. niger were more stable in solutions at different pH levels and allowed easier separation from aqueous solution than free spores, suggesting significant potential for future industrial application.

In this work, the reaction films were generated on the Ti–6Al–4V alloy by means of high-speed wire electrical discharge machining (WEDM-HS) technology in order to improve its microhardness and corrosion resistance. The microhardness was evaluated by using a nanoindentation tester. The corrosion behaviour was studied using measurements of potentiodynamic polarisation and electrochemical impedance spectroscopy. The experimental results showed that the processed alloys presented a higher microhardness than the matrix, and the thicker film on the surface had a greater microhardness. Additionally, the corrosion resistances of the processed alloys were superior, which could have been due to the lower corrosion current densities and the higher impedance values. Furthermore, the corrosion current densities of the processed alloys would decrease with thicker reaction films. This research provides important insights into the surface modification of titanium alloys.

The important issue of selection of gate dielectrics to reduce short channel effects (SCEs) is presented along with the study of different channel materials in transistors. A comparative study of performance was carried out of silicon dioxide (SiO₂), aluminium oxide (Al₂O₃), hafnium oxide (HfO₂), lanthanum oxide (La₂O₃) and titanium dioxide (TiO₂) as gate dielectrics for Si double gate field-effect transistor (FET), Si gate all around (GAA) nanowire FET (NWFET), indium arsenide GAA NWFET and carbon nanotube (CNT) FETs within non-equilibrium Green's function formalism. Simulated results show that TiO₂ is better gate dielectric as compared with SiO₂, Al₂O₃, HfO₂ and La₂O₃, with near ideal subthreshold swing (60 mV/decade), lower I _off, improved drain-induced barrier lowering and high transconductance (g_m ). Also, the gate capacitance (C _g), cut-off frequency (f _T) and switching time (τ) improve with the high-k dielectric materials. Furthermore, the study of different channel material shows that CNT has better SCEs, smaller C _g with τ ranging from 13.5 to 12.5 fs suitable for digital applications and f _T of about 7–9 THz.

The Al–Al₄C₃ nanocomposite was produced via mechanical alloying of Al 6 wt% C mixture for a predetermined time (up to 20 h), followed by annealing. The structural evolution was characterised via X-ray diffraction and transmission electron microscope equipped with electron energy loss spectrometer. In addition, focused ion beam–scanning electron microscopy was used for locating and analysing the reinforcing particles. During milling, the size of aluminium particles reached the nanometre scale with a 54 nm size. After annealing, carbide was homogeneously distributed in the nanostructured aluminium particles with an average size of 50 nm, result in an average hardness of 320 HV. This was observed for the powder that was mechanically milled for 20 h and that underwent annealing from room temperature to 540°C and was maintained at this temperature for 4 h.

A new kind of poly(methyl methacrylate–butadiene–styrene) (MBS) core/shell latex nanoparticles with amine groups in the shell was prepared via multistep seeded emulsion copolymerisation of styrene, methyl methacrylate and N,N-diethylaminoethyl methacrylate (DEAEMA) onto the poly(styrene–butadiene) seed latex in the presence of anionic emulsifier, and their CO₂-triggered coagulating properties were investigated. Results showed that the emulsion polymerisation could be performed smoothly, and the coagulating time of the amine-containing MBS latexes depended on the DEAEMA content and solid content. The MBS solid powder could be easily obtained by drying and grinding without any extra treatment after the coagulation. A coagulating mechanism of the in-situ opposite charge interaction and the transformation from sodium laurate to lauric acid was proposed, which was demonstrated by transmission electron microscopy, dynamic light scattering, surface tension and Zeta potential measurements. This facile and smart method might open up industrial potential in cost-effective and environment-friendly latex coagulation.

Chemical oxidation of graphite and subsequent exfoliation allow the large-scale production of isolated graphene oxide (GO), in which the induced oxygen-containing functional groups on GO surface were then removed by means of reduction processes. The residual functional groups including carbonyl, hydroxyl and epoxy groups as well as the newly formed defects, significantly influence the physical properties of reduced GO (RGO). Here, RGO structures were generated through a thermal reduction process of GO using molecular dynamics simulations, in which the transformation of functional groups and the formation of non-hexagonal rings/defects were captured. The results suggested the formation of two RGO structures with different contents of functional groups at C/O ratios of about 11 and 13. These structures were obtained using various durations of the thermal reduction process. The dependence of tensile behaviour of RGOs on the structure and chirality as well as the influence of temperature on the tensile properties of RGOs were also evaluated. It was found that the strength and Young's modulus of RGOs decreased as a result of the residual functional groups and newly formed defects, and were decreased with the environment temperature.

This work demonstrates experimentally a simple and practical low-cost surface plasmon resonance (SPR) system towards sensing applications. The cost is minimised through the elimination of many bulky optical components such as collimation lenses and prism. An off-shelf white light-emitting diode is directly coupled to a gold coated glass slide at a proper incident angle, while the output is collected with a bare multimode optical fibre mounted at the same incident angle and connected to a commercial spectrometer. Proper alignment of the components is achieved through building a mount using three-dimensional printing technology. The developed system is tested with glycerol solutions having different concentrations and the detection limit measured in the order of 10⁻⁴ RIU (refractive index unit). The system cost can be further reduced through mass production and when a low-cost in-house spectrometer is built while keeping the same precision.

The most important issue during synthesis of nanoparticles (NPs) is to avoid particle agglomeration and adhesion. There have been several attempts to use special substances such as organic surfactants, polymers and stable ligands for this purpose. In this study, silver NPs were synthesised with and without gelatin macromolecules, as a green natural biopolymer, which resulted in NPs with varying shapes and sizes. The effect of morphological characteristics on the antibacterial and antifungal properties of the synthesised NPs were studied, by comparing Gram-negative (Escherichia coli) versus Gram-positive (Staphylococcus aureus) bacteria as well as fungi (Candida albicans) by calculation of minimal inhibition concentration value. The results corresponded well with the assumptions on the effects of shape and size on the antibacterial and antifungal properties of the studied NPs.

A simple calcination method was explored to synthesise the tremella-like molybdenum disulphide (MoS₂), Mo trioxide (MoO₃)/MoS₂ and MoO₃ nanoplates by using the pristine MoS₂ nanosheets as the precursor. The possible formation and growth mechanism from the pristine MoS₂ to the tremella-like MoS₂, MoO₃/MoS₂ nanoplates and MoO₃ nanoplates was proposed. It was found that the calcination temperature was a key factor for the formation, ingredient and phase structure of the three samples. The adsorption properties of the three samples for an aqueous solution of methylene blue (MB) at room temperature were investigated. The results revealed that the products exhibit the better adsorption capacities with increasing the ingredient of MoO₃ in the transformation process from MoS₂ to MoO₃. Therefore, the pure MoO₃ nanoplates have the highest adsorption and removal rates, which reached 96.9% at MB concentration of 10 mg/l and 90.9% at MB concentration of 20 mg/l.

Ordered monolayer of silica nanoparticles assembled on solid substrates is useful for a variety of promising applications in photonics, plasmonics, and solar cell. Nanoparticles are usually assembled into close- or non-close-packed monolayer (CPM) form. The non-close packed monolayer can be directly deposited from mono-dispersed colloidal suspension onto a solid substrate in terms of using complicated techniques or tuning the size of nanoparticles in the CPM. An effective method for forming the non-close packed monolayer of silica nanoparticles is reported. Silica nanoparticles are self-assembled into the CPM on silicon substrate. The size of silica nanoparticles is tuned by high frequency vapour etching. The dependence of the size and shape of silica nanoparticles on etching time is presented. The effect of sintering conditions on the etching process is also investigated.

In this study, a novel AlGaN/GaN power rectifier with an integrated lateral composite buffer diode (IBD-Rectifier) for reverse blocking capability improvement is proposed and investigated by Sentaurus simulations (this paper includes only simulated data and no real experimental result). AlGaN buffer layer under the anode is adopted to realise great high reverse blocking capability. A minimum turn-on voltage of 0.6 V and a maximum breakdown voltage (BV) >1.3 kV are simultaneously obtained in the IBD-Rectifier, resulting in a high Baliga's figure of merits BV ²/R _on,sp (R _on,sp is specific-on resistance) of ∼3000 MW/cm². In comparison with MIS-gated hybrid anode diode and conventional schottky barrier diode, the IBD-Rectifier delivers an excellent theoretical method to achieve superior performances in high-efficiency GaN power applications.

Hafnium carbide nanowires were synthesised by a Ni-catalysed vacuum chemical vapour deposition method below the eutectic temperature of the Ni–C–Hf alloy. The zigzag growth behaviour of the hafnium carbide nanowires resulting from metastable growth was investigated by transmission electron microscopy in order to understand the sub-eutectic growth. Three typical zigzag configurations at joint angles of ∼125°, 45°, and 90° can be observed from the synthesised nanowires, where the structure with an angle of ∼125° is the most common, formed via a change in the growth direction from to , or vice versa. The 45° zigzag structure is the second most common and is formed by alternating the axial direction three times between 〈011〉 and 〈001〉. The number of the zigzag structures with a 90° angle is the most rare among the three types and is formed by the change in growth direction between two energy-equal directions, from to . Although alternating the growth direction brings about the zigzag geometry, the zigzag structured hafnium carbide nanowires have a single-crystal structure. In addition, the surface energies of the crystal planes play an important role in the growth of the hafnium carbide zigzag nanowires.

The structure of polymer/nanoparticle interfaces was discussed using X-ray diffraction measurements with mixtures of polyacrylates [poly(ethyl acrylate) and poly(n-buthyl acrylate)] and nanoparticles (Al₂O₃ and SiO₂). The amorphous halo with two peaks present for the bulk polymers changed, both in diffraction angle and intensity, into a peak in the mixtures. A novel polyacrylate structure at the interface (5–10 nm) with nanoparticles was formed with a specific chain conformation that was different from the bulk structure observed using Fourier transfer infrared spectroscopy.

In this study, porous K⁺-containing flower-like delte-MnO₂ constructed by numerous thin two-dimensional nanosheets was fabricated by a hydrothermal procedure. Its flower-like morphology was revealed by scanning electron microscopy. The construction units, the ultrathin sheets, were observed from transmission electron microscopy. Its delte-type crystal was characterised via X-ray diffraction. Its porous structure was convinced through N₂ adsorption–desorption isotherms. The properties of delte-MnO₂ nanoflowers as an active electrode constituent for electrochemical capacitors were examined by cyclic voltammetry and galvanostatic charge–discharge in 1 mol l⁻¹ Na₂SO₄ electrolyte, and a specific capacitance of 227.2 F g⁻¹ was obtained at a current density of 0.05 A g⁻¹. The obtained delte-MnO₂ shows a good long-term stability, suggesting it is a potential electrode material for capacitors.

Aluminium (Al) nanoparticles absorbed by oleic acid (OA) were prepared to study the effect and mechanism of OA on the stability and rheology of a nanoAl/exo-tetrahydrodicyclopentadiene (JP-10) bi-phase system. The absorption layer was characterised by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and energy dispersive X-ray spectroscopy. The effect of OA on the stability and rheology of nanoAl/JP-10 suspensions was measured. Results show that OA reduces the surface tension of JP-10 and the contact angle between the two phases. The absorption of OA on the surface of the particles occurred through the reaction between the −COOH of OA the −OH of Al particles. The amount of absorption increased as the concentration of OA increased. Adding OA enhanced the stability of the nanoAl/JP-10 bi-phase systems by hindering particles aggregation. A suspension with 5.0% solid load demonstrated no clear layer separation 1 month after preparation with 1.0% OA. OA also reduced the viscosity of the systems. A 0.5% concentration of OA is best for a system with 20% solid load. The viscosity-reducing effect of OA was determined by its comparative amount, and the ratio of OA/Al should be above 2.5%.

Silver (Ag) objects tarnish when expose to the human sweat or atmospheres polluted by sulphide. In this work, a waterborne and transparent polyurethane/Ag (WPU/Ag) nanocomposite was synthesised and applied on the surface of the Ag sample with enhanced anti-bacterial and also protection against the tarnishing in the corrosive solutions. Ag nanoparticle in the WPU/Ag was investigated by field-emission scanning electron microscopy and transmission electron microscopy. To study the anti-tarnishing behaviour of the Ag samples, the bare as well as the coated samples were immersed in corrosion solution of 0.35 wt% Na₂S which is a simulating solution of the human sweat. The corrosion products were then studied with X-ray diffraction and energy-dispersive X-ray spectroscopy. The bare Ag surface was covered completely by a black layer after 60 min immersion in the corrosion solution. However, the presence of either waterborne polyurethane (WPU) or WPU/Ag coatings was remained on the surface and protected the substrate from tarnishing. Anti-bacterial properties of the samples were determined by disc diffusion and the minimum inhibitory concentration methods. Anti-bacterial effect of the Ag coated by WPU/Ag was greater than the bare substrate, whereas the WPU coating lost the anti-bacterial effect of the Ag substrate.

The Ag-decorated silica nanoparticles (termed core–shell Ag@SiO₂ mesosphere) have been successfully fabricated by an aerosol method in this Letter. The size of Ag nanoparticles (AgNPs) can be well controlled by tuning the calcination temperature and the AgNPs on the surface of silica can be gradually grown with the increase of the calcination temperature. Moreover, the catalytic activity of nanocomposites for a reduction of 4-nitrophenol (4-NP) was studied in this Letter. The as-prepared nanocomposites with well dispersed AgNPs possessed distinguished catalytic activities in catalysing for the reduction of 4-NP by NaBH₄ in the aqueous phase, which was detected by UV–vis absorption spectroscopy. The results showed that the nanocomposites presented a distinguished catalytic activity compared to the pure spherical AgNPs.

Dynamical and precise arrangement of micro-objects into the specified various pattern offers great flexibility and potential as platforms for many scientific applications, especially in bio-sensing and biomedical fields such as bio-MEMS and Lab-on-a-Chip. Multi-beam optical tweezers are one of the most suitable tools for assembling precise dynamic arrays of micro-objects. Herein, a dynamic patterning method based on software-oriented approach is proposed (i.e. time-shared scanning technique) using the dual optical tweezers with a microlens array. The proposed method can expand the patterning capability of this dual optical tweezers system to simply fabricate various quasi-periodic structures. The work also demonstrates kaleidoscopic patterning (periodic or symmetric arrangements such as Escher's paintings) of numerous microbeads and subsequent morphing. In the demonstrations, microbeads with different properties (size and colour) as well as homogeneous microbeads are arranged dynamically into the specified patterns, including their clusters.

Many research papers have demonstrated that the starch-based fibres showed poor water stability. In this work, it is proven that citric acid can cross-link starch and improve the water stability of centrifugally spun starch-based fibres. The effect of citric acid concentration on fibre morphology and water stability was studied. Fibre morphology was characterised by scanning electron microscopy and optical microscope. Fourier transform infrared analysis was used to investigate structure changes of fibres during cross-linking.

This work reports a novel flexible triboelectric nanogenerator (TENG) based on the conductive nylon membrane (NM). Multiwall carbon nanotubes were directly composited with the poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) solution and deposited on one side of the NM surface through vacuum filtration method. The sheet resistance of the fabricated composite material was found as 24 Ω/square and the charged output voltage of 10 µF capacitor was 7.9 V. The NM-based TENG showed robust output power when NM contacted with friction layer of polytetrafluoroethylene (PTFE). The friction layer was consisted of adhesive conductive fabric attached with PTFE. Due to its well flexibility, simple process of fabrication and high output performance, the generator has much potential for powering up portable electronics.

In(OH)₃ microcubes have been successfully synthesised by a direct precipitation in solution at room temperature without using any surfactant or template. Furthermore, the In₂O₃ microcubes were obtained through calcining the In(OH)₃ microcubes. The results show that the as-prepared In(OH)₃ and In₂O₃ products have a cube shape with a mean edge length of 190 and 155 nm, respectively. The self-assembly process via orientation attachment is proposed in order to explain the growth mechanism for the microcubes. Upon ultraviolet excitation, a broad blue photoluminescence emission with its maximum intensity centred at 466 nm is shown, which is due to the oxygen deficiencies in the In₂O₃ microcubes. It endows these microcubes with potential application, such as liquid crystal devices, solar-energy conversion, optical and electric devices.

Response surface methodology coupled with the central composite design (CCD) was employed to optimise the significant parameters in the synthesis of silver nanoparticles (AgNPs) by chemical reduction method to obtain smaller average particle size. Different parameters such as the ethylene glycol (EG) concentration as reducing agent, the polyvinyl pyrrolidone (PVP) content as stabiliser and the pH were selected as they have the dominant effects on the particle size of AgNPs. Each of these parameters was studied at three levels. The average particle size of AgNPs was considered as the response value and determined by dynamic light scattering (DLS) analysis. The statistical analysis showed that the pH emerged as the most significant parameter influencing the average particle size and after that, the PVP content was also a significant parameter. The AgNPs synthesised under optimal conditions (6.88 M of EG, 0.5% of PVP and pH = 11) were characterised by UV–vis spectroscopy, X-ray diffraction (XRD), DLS, zeta potential, field emission scanning electron microscope and energy dispersive X-ray analysis. The XRD pattern showed the face-centred cubic silver and the average crystallite size of AgNPs was 30 nm. The average particle size of AgNPs was 37.35 nm according to DLS analysis, which was in good agreement with the predicted value (37.65 nm) by CCD.

A facile and low-cost chemical method is still in need to make Fe₃O₄ submicrospheres with the size below 200 nm. In this study, Fe₃O₄ submicrospheres of ca. 173 nm with soft-magnetic properties were made by conversion of goethite under solvothermal conditions, and exhibited the good catalytic activity and reusability for selective oxidation of benzyl alcohol to benzaldehyde with H₂O₂ in water (yield: 43.5–46.2% after being recycled seven times).