This work analyses the nonlinear coupled axial–torsional vibration of single-walled carbon nanotubes (SWCNTs) based on numerical methods. Two-second order partial differential equations that govern the nonlinear coupled axial–torsional vibration for such nanotube are derived. First, these equations are reduced to ordinary differential equations using the Galerkin method and then solved using homotopy perturbation method (HPM) to obtain the nonlinear natural frequencies in coupled axial–torsional vibration mode. It is found that the obtained frequencies are complicated due to coupling between two vibration modes. The dependence of boundary conditions, vibration modes and nanotubes geometry on the nonlinear coupled axial–torsional vibration characteristics of SWCNTs are studied in detail. It was shown that boundary conditions and maximum initial vibration velocity have significant effects on the nonlinear coupled axial–torsional vibration response of SWCNTs. It was also seen that unlike the linear model if the maximum vibration velocity increases, the natural frequencies of vibration increases too. To show the effectiveness and ability of this method, the results obtained with HPM are compared with the fourth-order Runge-Kutta numerical results and good agreement is observed. To the knowledge of authors, the results given herein are new and can be used as a foundation work for future work.

Clad-modified fibre optic ammonia sensor was developed subsequently using pure V₂O₅, MoO₃, and its composites with TiO₂. Prior to the sensing measurement, the composite was synthesised and studied for the structural and microstructural properties using powder X-ray diffractometer and field emission scanning electron microscope. The analysis confirms the existence of nanocrystalline anatase phase TiO₂ in the grain boundaries of microcrystalline V₂O₅/MoO₃ in the composites. Ammonia sensing measurement was performed for different concentrations of ammonia exposures up to 500 ppm. The obtained response was applied to calculate the sensitivity and it was found to be superior for the clad modified with composite material as compared to the pure microcrystalline samples are discussed in detail.

Nylon 6 (PA6) fibre has many advantages such as high strength, wear resistance, light weight, and good elasticity. However, PA6 fibre is prone to deformation in use and the antistatic ability is poor. In this Letter, the dispersion of carbon black (CB) was improved by physical methods and then added to the nylon 6 (PA6). The authors had studied that the dispersion of modified and unmodified CB in PA6 fibres with excellent mechanical properties and electrical conductivity. The results of Zeta potential and particle size test showed that the size of the CB particle modified was decreased and the absolute value of Zeta potential on the surface was increased. The results of scanning electron microscopy showed that the CB had a good dispersion in PA6; the results of thermogravimetric and Fourier transform infrared analysis showed that polystyrene sodium sulphonate was successfully coated on the surface of CB; when 5% modified CB was added in PA6 fibres, the mechanical properties of PA6 were hold up well. Interestingly, when 5% CB modified was added in PA6 fibres, the resistance of CB modified/PA6 fibre with excellent mechanical properties was reached up to 4.89 × 10¹¹ Ω.

The ZnSnO₃ microspheres were fabricated with water-soluble biopolymer sodium alginate (SA) as a crystal growth modifier under hydrothermal conditions. The gas-sensing properties of ZnSnO₃@SA were tested under the illumination of UV light at room temperature. The results showed that the ZnSnO₃@SA sensor exhibited better HCHO gas response than pristine ZnSnO₃ sensor, which was ascribed to the introduction of SA that changed the size distribution of the microspheres. Test results of HCHO gas with different concentrations indicated that the ZnSnO₃@SA sensor had a good linearity. This approach would provide a potential route for the HCHO sensor to work at room temperature. In addition, the sensing mechanism was also discussed.

Herein, organic-free all-solid-state based perovskite solar cells (PSCs) are successfully fabricated by one-step method. The absorption position of the non-perovskite cesium lead iodide (δ-CsPbI₃) was significantly shifted towards longer wavelength side by substituting indium (In) ion with different stoichiometric ratio. The authors demonstrated a facile route to achieve high efficiency by the fabrication of room temperature stable mixed-phase CsPbI₃ perovskite. Photovoltaic efficiency of doped perovskite is four times increased compared to pure yellow phase CsPbI₃. To the best of the authors’ knowledge, this is the first demonstration of In-doped-CsPbI₃ based PSCs, which was fabricated under completely open-air atmosphere.

Metallic nanoparticles (NPs) exhibit interesting plasmonic characteristics that depend on their size, shape and dielectric medium. Any change in these parameters can lead to significant alternation in plasmonic behaviour of NPs. Plasmonic nanostructures are prepared by wet chemical approaches, which produce NPs with a moderate yield. Amongst plasmonic class of NPs, gold and silver are widely explored in sensors because of their strong plasmon excitation. Copper NPs (CNPs) are gaining increasing attention in plasmonic sensors because of its economic advantages over silver and gold. However, major limitations of these nanostructures are their low yield and poor colloidal stability. In this Letter, authors report scale up of CNPs yield by 100% and studied their colloidal stability in terms of changes in hydrodynamic size and its influence on surface plasmon resonance (SPR). It has been observed that SPR of CNPs is independent of their yield. A gradual decrease in SPR is observed with ageing. This can be attributed to the aggregation-induced microstructural changes in the dispersion. CNPs irrespective of their yield are stable up to 180 days beyond which they lose their colloidal stability and plasmonic properties. Loss of colloidal and plasmonic characteristics of CNPs can be attributed to enhanced hydrodynamic size.

Recently, electroplated cobalt platinum (CoPt) magnetic films have been developed that afford thick (up to ∼100 μm), high-energy-density (up to ∼100 kJ/m³) permanent-magnet microstructures. However, the aggressive electroplating conditions have shown to be incompatible with most thick-film photoresist mould materials, making patterning these films an unanswered technical challenge. In this work, it is reported a complete process flow of fabricating and removing SU-8 photoresist moulds to enable the ultra-thick patterned CoPt magnets on silicon wafers. The implementation of thick SU-8 2050 electroplating moulds makes it feasible to deposit 100 µm thick CoPt magnets in 4 h. A 25 nm thick sputtered titanium layer is used as a sacrificial layer to completely release the SU-8 mould in hydrofluoric acid after electrodeposition. Compared to prior research, significantly improved pattern definition and constant magnetic performance are observed and characterised by optical profilometer, scanning electron microscope, and vibrating sample magnetometer.

In this work, a nanocomposite of zinc oxide (ZnO) and cobalt ferrite (CoFe₂O₄) was synthesised with a facile preparation method in order to fabricate a nanosensor for acetaminophen (AC) sensing. The ZnO nanoparticles were electrochemically deposited onto glassy carbon electrode (GCE) coated with magnetic nanoparticles CoFe₂O₄. The morphology and structure of ZnO@CoFe₂O₄ nanocomposite were investigated by scanning electron microscopy and energy dispersive X-ray. The performance of the proposed sensor was characterised with cyclic voltammetry and differential pulse-voltammetry techniques. The ZnO@CoFe₂O₄/GCE nanosensor shows excellent electrocatalytic activity for AC oxidation in phosphate buffer (pH = 7) solution and it exhibits a good linear relationship and the low limit of detection (LOD). The ZnO@CoFe₂O₄/GCE showed good sensitivity, selectivity, stability, reproducibility, larger specific area and fast response in comparison with other reported sensors. The result calibration diagram of using the differential pulse-voltammetric technique has two linear ranges of 0.495–9.53 and 9.53–47.00 µm, and the LOD for AC by this method obtained 0.36 µm. The performance of this modified electrode was evaluated for measuring AC in some pharmaceutical formulations.

A tunnelling effect transistor based on copper phthalocyanine (CuPc) has been fabricated. CuPc is the active layer of transistors. The basic characteristics of the transistor are measured. The device shows unsaturated output characteristics. The output current can be modulated by demanding different gate voltage. At V _DS = 3 V and V _GS = 0 V, the drain-source current is 1.89 × 10⁻⁴ A. The current density is 4.73 × 10⁻³ A/cm². The tunnel injection model is used to analyse the carrier transport inside the transistor. The microscopic operating mechanism of the device is investigated. The results show that the operating current of the transistor conforms to the tunnelling effect theory.

In this work, a novel bipolar-field-effect composite transistor based on silicon carbide (SiC) Vertical Double-diffused MOSFET (VDMOS) is proposed and investigated for the first time. The novel device is controlled by a gate and is a composite structure of a parasitic Bipolar Junction Transistor (BJT) and a Vertical Double-diffused MOSFET (VDMOSFET), called SiC GCBT (SiC Gate-Controlled Bipolar-field-effect composite Transistor). The structure features using the base–gate short connection mode, instead of the base–source short connection mode, as the traditional SiC VDMOS. So that two conductive channels can be provided by the parasitic bipolar transistor and the metal oxide semiconductor structure for the new device, which not only can improve the integration degreebut also greatly increases the on-state current while the breakdown mechanism remains unchanged. As simulation results show that, compared to the traditional SiC VDMOS with the same parameters, SiC GCBT has the identical BV (about 800 V) and a V _th (2.98 V) that is reduced by a factor of 3, and its on-state current is 16.7 times larger than that of SiC VDMOS and is almost unaffected by the width of the Junction Field-Effect Transistor (JFET) region. In addition, under the same gate-controlled voltage, its switching speed can even be compared with that of the traditional SiC VDMOS.

In this work, graphitic carbon nitride nanosheets decorated like nickel oxide microspheres (NiO/g-C₃N₄, Ni/CN) were successfully synthesised by a simple hydrothermal method. The morphologies of the as-prepared samples were analysed by scanning electron microscopy and the diameter of the microspheres was found to be about 2.5 μm. At an optimum working temperature of 240°C, the response to 500 ppm CO is 2.729 for the Ni/CN-10 (10 wt% g-C₃N₄ modified NiO) sensor, which is much higher than those of the NiO sensor (1.408). Besides the higher response, the Ni/CN sensors also showed good repeatability and stability for CO detection. Excellent gas sensitivity properties can be attributed to the p–n heterojunction formed at the interface, which can provide more potential active sites for surface reactions. In addition, the sensitisation of g-C₃N₄ also plays an important role in the improvement of CO-sensing performance.

Hydroxyapatite microplates were synthesised by the Sol–Gel method using a mixture of calcium nitrate and potassium phosphate. The reaction took place at room temperature for 48 h, 300, 400, 500 and 600°C calcination temperatures were made in order to study the effect of this temperature on the growth and morphology of the nanostructures. Crystalline composition, functional groups and surface morphology were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy and scanning electron microscopy. Hydroxyapatite microplates with average dimensions of 40 μm × 13 μm was obtained, the morphology of the surface is well defined in the form of a plate composed of a large number of small nanofibers. According to the studies by XRD, preferential orientations in the directions (200) and (002) were observed which is attributed to the conditions of synthesis.