In this work, un-doped and Sn-doped hierarchical ZnO particles with high dispersity were successfully fabricated by a facile liquid reaction. The prepared samples are characterised by X-ray diffraction and scanning electron microscopy. The as-synthesised hierarchical ZnO particles with a diameter of ∼1.5 μm were obtained by considerably intersecting thin nanosheets of ∼20 nm thickness. The morphology of ZnO structures can be varied by adjusting reaction parameters, e.g. reaction temperature, calcination temperature, and dopant concentration. On the basis of experimental results, the gas-sensing measurement displays that the sensor based on Sn-doped ZnO microstructures have a low detection of 10 ppm ethanol at an operational temperature of 250°C, demonstrating its outstanding gas-sensing performance. Therefore, the flower-like Sn-doped ZnO have prospective applications in a multifunction ethanol sensor. Moreover, the fabrication method reported in the work is facile, flexible and operable, it is possible to extend to synthesise other types of metal oxide-based applications in various fields.

A scalable technique for controlled synthesis and surface modification of magnesium hydroxide using the microemulsion method at room temperature was studied. The magnesium hydroxide nucleation and growth were carried out in numerous identical nanoreactors formed by cetyltrimethyl ammonium bromide/isopropanol/cyclohexane/water microemulsion. The crystal structure, morphology, thermostability and surface performance of the product as flame-resistant material were investigated by X-ray diffraction, scanning electron microscopy, thermogravimetry/differential scanning calorimetry, fourier transform infrared spectroscopy and dispersion tests. The results indicated that the product had a flake structure and belonged to a hexagonal system, the highly defined nanoflakes had a uniform diameter, and the diameter size can be well controlled in the range of 40–65 nm by adjusting the ratio of water to surfactant. The thermostability analyses showed a narrowed decomposition temperature range. Furthermore, the surfactant in microemulsion was adsorbed on the particles surface, making the surface of magnesium hydroxide changed from hydrophilic to lipophilic. Therefore the reported magnesium hydroxide material has a better flame resistance and compatibility with polymer materials than conventional magnesium hydroxide.

Solvent, as one of the important factors, influences the composition and morphology of material during its preparing process. Ethylene glycol, as a good solvent, has good properties such as low toxicity, low cost, relatively high boiling point, good solubility and certain reducibility. Here, the work investigates the effect of ethylene glycol as the solvent on composition and morphology of nickel phosphide and find that the addition of ethylene glycol into aqueous solution will lead the composition of nickel phosphide from the pure Ni₂P phase to a mixture of Ni₂P and Ni₁₂P₅, and the morphology from the close packed structure of nanoparticles to the loose structure.

A new structure of N-type Silicon-on-insulator (SOI)-Like Bulk Silicon (N-SL-BS) metal–oxide–semiconductor field-effect transistor (MOSFET) is proposed to improve the reliability of SOI MOSFET mainly with regards to their self-heating effect and electro-static discharge (ESD) events based on two-dimensional numerical simulation. The new device employs p/n–/p + structure on Si, in which the n-layer is made of Si carbide (SiC), a wide bandgap material. The built-in electric field fully depletes the n-SiC layer and forms an SOI-like feature with a p + layer underneath. Simulations are first implemented in self-heating conditions, to investigate their drain current and temperature ramping. More importantly, ESD pulses assuming the human body model are applied to test their response and observe which device was first to fail using an I–V curve and hole current density distribution. Results show that the new device exhibits superior reliability when compared with a traditional SOI MOSFET. The avalanche breakdown voltage improves nearly 33% and the highest temperature of the global device is more than three times lower than that of an SOI MOSFET subjected to ESD pulses with a peak current of 7 mA.

To avoid the fabrication complexity and cost of nanoscale devices, a dual metal gate (DMG) in polarity controlled electrically doped tunnel field-effect transistor (ED-TFET) has been introduced first time for DC, analogue/radio frequency (RF) and linearity performance improvement. The formation of n+ drain and p+ source regions are done by applying polarity biases of PG-1 as 1.2 V and PG-2 as −1.2 V, respectively, over the silicon body in DMG-ED-TFET. Different analogue/RF and linearity performance metrics of DMG-ED-TFET are evaluated using ATLAS device simulator and compared with that of ED-TFET. The figure of merits (FOMs) studied in this work for DMG-ED-TFET are in terms of transconductance, gate-to-drain capacitance, gain bandwidth product, cut-off frequency and linearity parameters such as third-order transconductance coefficient (), VIP3, IIP3 and IMD3. From the simulations, it is found that DMG-ED-TFET achieves significant improvement in these FOMs as compared to ED-TFET due to introduction of dual metal at gate electrode (gate workfunction engineering). The work has also optimised the proposed device to attain optimum analogue/RF and linearity performance.

In this work, the authors prepared a novel magnetic photocatalyst by grafting of Preyssler-type polyoxometalate, H₁₄ [NaP₅ W₃₀ O₁₁₀] onto Fe₃O₄ nanoparticles via an internal layer of silver nanoparticles. The obtained nanocomposite has been characterised by electron dispersive X-ray, transmission electron microscopy and scanning electron microscopy. The activity of the synthesised nanomagnetic photocatalyst was tested by the photocatalytic decolourisation of rhodamine B under UV light irradiation in the study’s designed reactor. It was found that, compared to pure Preyssler, decolourisation of rhodamine B was occurred four times faster using the synthesised magnetic nanocomposite with easy separation. The magnetic nanocatalyst was separated after ending the reaction and recycled. It just showed 2–3% decrease in catalytic activity after four recycling.

Additive manufacturing (AM) of spongy (cancellous) microstructures in the development and application of piezoelectric sprayers was investigated. The structures featuring microfluidic channels were made of solid polylactic acid (PLA) by fused deposition modelling (FDM) designed with a width of 35 mm, a depth of 25 mm, a height of 56 mm, and a cross-layer thickness of 2 mm. In total nine network structures were altered with the line widths (W _d) from 300 to 500 μm and the line spacing (S _d) from 250 to 400 μm. Then, one piezoelectric plate and another micronozzle array were assembled with the structures as a microactuator. The piezoelectric actuator had a resonance frequency of 107.8 ± 1 kHz, in which it generated microsprays of 3 ml water with a typical volumetric rate of ∼1.1 ml/min. On the basis of FDM with PLA, the works’ dimensional error analysis showed that the minimum AM errors (<5%) between the design and actual dimensions occurred with the W _d of 350 μm and the S _d of 300–350 μm. In addition, they experimentally discovered anisotropic wettability and different roughness of the PLA layered surfaces, largely concerning the microfluidic performance of the network structures of the piezoelectric sprayer.

In this study, ZnO-based nanocomposites including ZnO/CuO (S₁), ZnO/MnO (S₂), and ZnO/MnO/CuO (S₃), were synthesised. S₁, S₂, and S₃ were characterised through Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) techniques. Also, the antimicrobial property of the samples was examined against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli through the colony forming count method. FTIR analysis confirmed the presence of Zn–O, Mn–O, and Cu–O in the samples. The crystalline structure of the sample was analysed by XRD. The surface morphology of the prepared compounds was studied with SEM images. EDS technique was employed for ensuring the presence of Zn, Mn, and Cu elements in the samples. The results clearly showed S₁, S₂, and S₃ had high-antimicrobial activity especially for S₃.

A surface potential-based analytical capacitance model is proposed for gate-on-source–channel silicon on insulator (SOI) tunnel field effect transistor (GOSC TFET). The capacitance in the GOSC TFET is evidently shared by the gate-to-source capacitance which reduces the miller capacitance and leads to better switching speed in the circuit application. The effect of drain voltage, gate voltage, gate oxide thickness and source doping on the capacitance has been analysed in detail. The good matching between the modelled and Technology Computer-Aided Design (TCAD) simulated surface potential leads to the accurate calculation of capacitance. The validation of the capacitance model is done by comparing the model result with the simulation result and a good agreement between them validates the model formulation.

The work proposes a one-dimensional photonic crystal (PC) filter with (Si/SiO₂) ^N structure, which is used to filter in the visible light band. The optical properties are simulated theoretically by using the transfer matrix method. Propagating properties under different incident angles and different period numbers for both Transverse Electric (TE) mode and Transverse Magnetic (TM) mode are studied. A photonic bandgap (PBG) is found between 450 and 700 nm. For both TE and TM modes, the blue shift can be found as the incident angle increases. The PC films are prepared by radio-frequency (RF) magnetron sputtering experimentally. The experimental results are in accordance with the simulation results. The results indicate that the PBG is related to the incident angle and the period number, and increasing the period number is a feasible way to ensure the stability of the PBG. The studies are beneficial to the design of the PC filter in the future.

Capillary-driven microfluidic devices have a great potential for the point-of-care testing systems based on the advantages of self-pumping, low reagent usage and rapid detection. Here, the study presents a lidless Si-based capillary-driven microfluidic device, comprising two inlets for sample and buffer loading, a snake-shaped microchannel (120/0.05/0.025 mm in length/width/depth) as a flow resistor, a micropillar array (25/5/8 μm in height/diameter/pitch) as a capillary pump and a vent. It was fabricated with lithographic technique in combination with deep Si etch technique. A simple and stable surface hydrophilisation modification method was demonstrated on the device by forming a self-assembly monolayer through Cu-catalysed azide-alkyne cycloaddition reaction. The surface modified device allowed controllable autonomous capillary flow delivery with a contact angle of around 40° stabilised for at least 90 days. The design of two inlets with one common long snake-shaped microchannel provided the sequential capillary flow generation and propagation with controlled flow rate and propagation distance, while the micropillar array with a high aspect ratio of 5 was considered as an effective capillary pump. Based on the obtained results, the proposed device makes possible for the on-chip biosensing applications as a part of integrated point-of-care testing systems.

In this work, the authors prepared drug-loaded ultrafine starch/polyethylene oxide (PEO) fibres through centrifugal spinning, which use the poorly water-soluble drugs ibuprofen (ibu) and ketoprofen (ket) as model drugs. The obtained fibres were treated by acetic acid/glutaraldehyde solution (1/1, v/v) for 12 h at 40°C, in order to remove residual sodium hydroxide in fibres and improve the water stability. The morphology, chemical structures, and mechanical properties of obtained fibres were investigated. In-vitro drug release tests revealed that more than 75% of loaded drugs could be released from fibrous membranes without initial burst release (>80% in the first 2 h). The ibu-loaded fibrous membranes showed a sustained release period as long as 24 h, while the ket-loaded fibrous membranes could release more than 48 h. These fibre-based delivery systems are therefore proposed to be good candidate drug formulations, especially for improving solubility and bioavailability of poorly water-soluble drugs.

In this work, turbulent convective heat transfer of propylene (R1270)-based nanorefrigerant in a circular tube with a uniform heat flux of 20 kW/m² is numerically investigated using different types of nanoparticles namely Al₂O₃, CuO, SiO₂ and ZnO with a volume concentration ranging from 0 to 5%. Computations have been carried out using the commercial CFD code Fluent for Reynolds number ranging from 20,000 to 100,000 and a nanoparticle diameter of 30 nm. Results in terms of the average convective heat transfer coefficients of both pure R1270 and R1270-based nanorefrigerants have been compared successfully to values obtained using correlations from the literature. It is found that among nanorefrigerants studied, R1270/CuO performs the best, followed in order by R1270/Al₂O₃, R1270/ZnO and R1270/SiO₂. It is also shown that the convective heat transfer coefficient is enhanced by increasing the Reynolds number and the nanoparticles volume concentration.

Herein, lithium-rich manganese-based cathode materials xLi₂MnO₃·(1 − x)LiNi_0.5Co_0.3Mn_0.2O₂ with different chemical components (x = 0. 4, 0.5, 0.6 and 0.7) were prepared by a simple co-precipitation method. The effects of different chemical components on the crystal structure and electrochemical properties of the lithium-rich manganese-based cathode materials were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, charge–discharge, cyclic voltammetry and electrochemical impedance spectroscopy. The results indicate that the sample xLi₂MnO₃·(1 − x)LiNi_0.5Co_0.3Mn_0.2O₂ (x = 0.5) shows an optimum electrochemical performance: the first discharge capacity is high up to 240.71 mAh g⁻¹ at 0.1 C; the discharge capacity can be maintained at 153 mAh g⁻¹ after cycling 50 times when measured at a high rate of 2 C, and the good cycle stability at a high charge–discharge rate, where the discharge capacity was maintained at 123.26 mAh g⁻¹ after 100 cycles at 5 C. Therefore, it can well balance the relationship between the specific capacity and rate capability.

Many micro-electro-mechanical systems applications suffer from large oscillations that come from high-quality factors. Designing feedback controllers is challenging because of the very limited phase margin. This work proposes a feedforward compensator approach to cancel the oscillation behaviours without the constraints of the stability margins. The essential element of this mechanism is to create a series of zeros to cancel the undesired oscillation poles. It is a practical solution because: (i) the selection of the parameters of the compensator is straight forward and robust to the model variations and (ii) the implementation uses a pipeline digital circuit architecture that enables MHz range bandwidth.

In this study, it is explained how spherical particles of poly(methyl methacrylate) (PMMA)/ZnO were synthesised in the presence of a polymer matrix of galactopyranose for their control growth. The objective of this research is to show the development of particles using the sol–gel method and the participation of a polysaccharide network. This method can increase the formation of stable spherical particles due to the hydrogen bonds junctions present in the walls of the polysaccharide network. The results of the formed tablets immersed in simulated body fluid indicate that there is no evidence of corrosion in the presence of PMMA/ZnO nanoparticles. The maximum roughness average (R _max) and roughness value (R _a) were 0.41 and 1.27 nm, respectively. The absorbance values showed significant changes when 10% polysaccharide concentration was used both in the presence and absence of the PMMA/ZnO nanoparticles. The particles were characterised by scanning electron microscopy, atomic force microscopy, powder X-ray diffraction (PXRD), X-ray elemental mapping, ultraviolet–visible spectrophotometry, and energy dispersive X-ray spectroscopy. The PXRD analysis shows the crystalline and amorphous phases of the composite at 400°C. The size range of the synthesised particles was between 30 and 100 µm.

In this work, a broadband absorber is designed for application in the terahertz region using graphene antidots array. The proposed absorber consists of an Au substrate, a polyethylene dielectric layer and a graphene sheet with antidot resonators. The geometrical dimensions of the antidot resonator and its array period, the graphene conductivity parameters and the dielectric layer height and refractive index are the parameters that determine the characteristics of the absorber such as bandwidth, centre frequency, the amount of the absorption and sensitivity to the incident wave incident angle and polarisation. The circuit theory and a broadband matching technique of the transmission lines are utilised in some steps of the design approach. Moreover, some rules of thumb are extracted for the absorber design in different frequencies. The designed absorber has a normalised bandwidth of 80% in the terahertz region, low sensitivity to incident angle and an absorption peak of 100%.

The regular and uniform size of nickel nanowires arrays has been successfully fabricated inside the nanochannels of anodic aluminium oxide (AAO) template by a simple paired cell method. The morphology, composition and structure of the nanowire arrays were characterised by field emission scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The results show that Ni nanowires possess smooth surface and high aspect ratio up to 15 with a diameter of 70–80 nm. Nearly 100% of the pores were filled by Ni nanowires, which have face centre cubic structure and [111] preferential orientation. Magnetisation measurement revealed that the nickel nanowires arrays have a unique soft magnetic property with small coercivity (Hc) of 11.38 Oe. A 3D self-seed nucleation coalescent process was proposed for the formation of nickel nanowires structures. The simple synthetic route is expected to be applied to the synthesis of other highly ordered metal nanowires arrays.

The study developed a novel quantitative detection method of homocysteine (Hcy), an independent risk factor for cardiovascular disease, based on an immunofluorescent test strip. The fluorescent nanospheres (F-NSs) were prepared by embedding fluorophores (Cy5) into poly(styrene-acrylate) copolymer nanospheres, then conjugated with streptavidin (SA) to obtain SA/F-NSs as a signal amplification label stored in sample diluents. Biotin–antibody was fixed on the conjugate pad to specifically capture S-adenosyl Hcy (SAH) in the sample, where SAH was transformed from S-adenosyl methionine (SAM) by Hcy S-methyltransferase catalysis using Hcy as a substrate, the formed SAH could be trapped by SA/F-NSs and biotin–antibody conjugates in a competitive way with SAH–bovine serum albumin fixed on the test line, a detection limit of 0.27 μM Hcy was achieved. The fluorescence intensity of F-NSs remained stable during 273 days of storage, the bioactivity of the test strip was stable during 12 months of storage, and the strip possessed good reproducibility (intra-assay variability of 5.8%). Furthermore, other structural analogues SAM and cysteine showed negative results, validating the excellent specificity of the strips.

A molecular dynamics (MD) simulation was performed on the nanocrystalline (NC) Cu with an edge notch under tensile loadings, with focus on the notch sensitivity. With the increase of notch size, the dominant deformation of material changes from the shear strain, which spreads throughout the entire sample, to a single shear band, which is induced by the stress concentration at the notch root. At the same time, the samples move from notch-insensitivity to notch-sensitivity. These findings offer significant guidelines for the application of NC Cu in engineering.

In this work, a new design of dual-gate source electrode (SE) dielectric-modulated tunnel field-effect transistor (TFET) biosensor with improved sensitivity and sensing speed has been presented. For this, P + (source) I (channel) N + (drain) type conventional TFETs structure is initially considered for comparison. Further to this, for the first time, an additional electrode is placed over the physically doped source region of the conventional biosensor with the negative supply voltage for extension of the cavity over the source region. The use of extra SE with negative supply voltage for the formation of cavity over the source region overcome the issues related to the formation of abrupt junction (at source/channel junction) and solubility limit of silicon material by the formation of a plasma layer of holes near to Si/HfO₂ interface in the source region. Moreover, the presence of extra biomolecules in the source cavity region of the proposed device further increases the concentration of plasma layer of holes near to Si/HfO₂ due to better coupling of SE and source region which is responsible for the improvement in sensing capability and sensing the speed of TFET biosensor. In this concern, a comparative investigation has been performed.

Bi₂O₃ quantum dots decorated TiO₂ nanobelt heterojunctions were synthesised by a facile two-step hydrothermal process. The Bi₂O₃ quantum dots highly dispersed on the surface of TiO₂ nanobelts resulted in more photosensitising sites and Bi₂O₃–TiO₂ heterojunctions, leading to the enhanced absorbance for visible light. The strong Bi₂O₃–TiO₂ interaction promoted the rapid transfer of photoelectrons from Bi₂O₃ to TiO₂ and thus inhibited their recombination with holes. Meanwhile, the high-surface area facilitated the adsorption and diffusion of reactant molecules. As a result, this photocatalyst exhibited highly enhanced photoactivity in degradation of organic dyes under visible-light irradiation, which also displayed strong durability owing to the strong Bi₂O₃–TiO₂ interaction against the leaching of Bi₂O₃ quantum dots.

Either microfibres or microspheres with different diameters were prepared from standard single-mode fibres with heating–stretching method. The influence of the different diameters of microspheres (from −49.4 to −208.04 μm) on the transmission spectra of silica microfibre with a diameter of −3 μm was studied through the whispering gallery modes. In addition, the temperature sensing characteristic of this microfibre–microsphere system was demonstrated with a sensitivity of −12.66 pm/°C in the interval of 30.18–38.52°C. Due to its simple, costless and miniature fabrication process, this microfibre–microsphere system will be the promising candidate for novel photonic devices and bio-chemical sensors.

Non-renewability, depleting resources and damage caused to the environment by mineral oil-based lubricants are the greatest concerns of this century. Recently, these issues have triggered a global trend to use vegetable oil-based lubricants in industries. Sesame oil (SESO) extracted from widely cultivated tropical crop – sesame (‘Sesamum indicum’) possesses distinctive characteristics such as low pour point and reasonable oxidation stability. However, the poor tribological properties of SESO limit its application as an industrial grade lubricant. Further improvement of these properties can aid its use as potential bio-lubricant in industries. This work encompasses the blending of micro and nanoparticles in SESO with the aim of enhancing its tribological properties to suit many industrial purposes. The tribological properties of SESO with nanoparticles having morphology variation spherical-shaped titanium dioxide (TiO₂) and rod-shaped zinc oxide (ZnO) are used. The significance of adding microparticles is also dealt with by using molybdenum disulphide (MoS₂). Tribological properties and stability of the above-formulated lubricants with and without the addition of surfactant to particles are studied. The rheological properties of the oil blends are examined using a rheometer. Studies indicate that rod-shaped ZnO blended SESO reduces the coefficient of friction and wear scar diameter by 24.04 and 13.74%, respectively.

Electrospinning method was used to prepare nylon 66 nanofibre membranes in solution mixed with chloroform/formic acid. These nanofibres were covered with (3-mercaptopropyl) trimethoxysilane (TPS) that has a sulphur group, making it a suitable host for Ag nanoparticles (Ag NPs). Spraying of the as-prepared nylon 66/TPS surface first with silver nitrate solution and then scattering with a mixture of N₂H₄/NaBH₄ used as reducing agents during the second process provides nanofibres with nylon 66/TPS/Ag NPs structure. Characterisation of the formed nanofibres was studied by Fourier transform infrared, scanning electron microscopy, X-ray diffraction and transmission electron microscopy techniques. The non-woven polyurethane coated with activated carbon particles and polyethylene mesh was utilised as the substrate and protective layers of as-prepared nanofibres, respectively. Finally, the antibacterial activity of nanofibre membranes against gram-positive and gram-negative bacteria was investigated by using the disk diffusion method and it was shown that the newly synthesised nanofibres presented very good antibacterial activity against the tested bacteria. The results of this study can be used for industrial applications such as antibacterial wound dressings or/and water disinfection filters.