Metal-sandwiched zinc oxide (ZnO)/titanium (Ti)/copper (Cu)/Ti/ZnO thin film systems were fabricated using magnetron sputtering technology and then annealed using a rapid thermal annealing system at temperatures from 100 to 400°C. The influence of the Ti film thicknesses and annealing temperatures on the surface morphologies, sheet resistance and optical properties were studied. The surface morphologies change a little with the annealing temperature rises. The sheet resistances reduce with the Ti film thickness or annealing temperature increasing. Both the max transmittance and figure of merit reduce with the increase of Ti film thickness. The max transmittance increases with the temperature increasing from 100 to 300°C and then reduces. However, the figure of merit increases with the temperature increasing which indicates that the metal-sandwiched ZnO/Ti/Cu/Ti/ZnO thin film system annealed at 400°C has the optimal performance.

The optical properties of Al-doped SmFeO₃ (SmFe_1−x Al _x O₃, for x varying from 0 to 0.15), were monitored by diffuse reflectance spectroscopy (DRS). The diffuse reflectance spectra were used to study the surface properties of the samples. The DRS spectra exhibit three reflection bands at different regions. The product was characterised by X-ray diffraction to confirm the formation of single-phase crystals of the perovskite structure. The bandgap, a major factor in determining the optical performance of any material, was found to be tunable with Al content (x).

A microfluidic paper-based analytical device (μ-PAD) and handheld colorimeter android application for quantifying the precise concentration of adulterants in milk are developed. A simple method to pattern polydimethylsiloxane for creating a hydrophobic barrier on filter paper using custom-designed rubber stamp containing the design of μ-PAD was used. The experiments were performed for the detection of urea, starch, salt and detergent ranging from 1 to 100 mg in 10 ml of milk. The user just needs to pipette drops of adulterated milk on a test spot and the results are obtained instantly. The authors believe that the developed platform can be used as a basis for low-cost, portable system for various fluid adulterants’ tests. The experimental database was used for the development of a colorimetric android application to calibrate the colour range for adulterants’ concentration detection. The limit of detection of colorimetric android application for adulterants urea is 5 mg, starch is 17 mg, salt is 29 mg and for detergent is 20 mg in 10 ml of milk. This kind of system is attractive for use in developing countries, in the field, or as an inexpensive alternative as compared with other methods for water and food safety.

Indium tin oxide (ITO) on polyethylene terephthalate (PET) substrate is characterised in terms of pH-sensitivity. Commercial ITO/PET sheet was cut in a shape of electrode and was connected to the gate-terminal of a metal–oxide–semiconductor field-effect transistor as the sensory part, creating an extended gate field-effect transistor (EGFET) pH-sensor. The quality of laser micromachining as well as the moulded ITO/PET electrode is investigated. The pH-sensitivity and linearity of the sensor signal are studied over time for a single hanging ITO/PET electrode. With the help of a constant-charge amplifier circuitry, the reference electrode, dipped in the measurement cell, is grounded. Therefore, the noise level, coupled into the sensor signal from environment, is decreased and also integration of the second sensor to the measurement cell becomes possible. The pH-measurement is carried out while EGFET pair, immersed into a buffer solution next to a pseudo-reference electrode, is working in differential mode to compensate for the high drift signal rate which is common for this type of sensors. As the result, a very low-cost EGFET-based pH-sensor is achieved based on commercially available products independent of costly cleanroom processes.

To optimise the performance of photo-field-effect transistor, a back-gate hybrid structure was developed. In this hybrid phototransistor, lead sulphide (PbS) thin film was prepared using physical vapour deposition as a photosensitive layer. Discontinuous and uniform PbS film was obtained by controlling the deposition rate and time of PbS powders. Amorphous indium gallium zinc oxide (IGZO) with high mobility was used as an active layer. In this work, The hybrid structure phototransistor shows an excellent performance: device mobility (μ) reach 8.7 cm²V⁻¹s⁻¹, and responsivity achieve 2.7 × 10⁴ A/W in visible spectrum and 5.7 A/W in near-infrared spectrum, respectively. Furthermore, the transistor exhibits detectivity up to 2.79 × 10¹³ cmHz^1/2W⁻¹. The device also exhibits characteristics of the ideal diode: the saturation current of the diode is as small as 0.422 nA, and the responsivity of diode is ∼0.74 A/W. Simplified manufacturing processes effectively reduce the cost of fabricated device and provide better device stability.

A multimode fibre Bragg grating (MMFBG) is experimentally demonstrated in this work. The light from the lead-in optical fibre transmits to the MMFBG, the Bragg gratings in multimode fibres show multiple reflection peaks due to the coupling among all bounded modes. Some reflection peaks are reflected back to the lead-out fibre core by the MMFBG. Finally, the spatial frequency spectra of the reflection peaks are detected by the detection device. As the temperature variates, the changes in the transmission spectrum will be observed. Experimental results show that the MMFBG responds to temperature and the temperature sensitivity is 0.0114 nm/^oC. The MMFBG has the advantages of compact structure, anti-electromagnetic interference, and stable chemical property, which has great potential in temperature measurement.

Al–Mg–Si alloy was treated through high-frequency impacting and rolling. Microstructures of different deformation layers were observed by transmission electron microscopy. The interaction mechanism between precipitated phase and dislocations for different deformation layer was studied. A detailed schematic of coordinated deformation dislocation mechanism around precipitated phase was established. Results show that lots of coordinated deformation dislocations are formed around the precipitated phase which is far away from the treated surface. With the decrease of distance from the treated surface, dislocation motion is blocked and dislocation lines gradually intersect, which speed up the segmentation and refinement of grains.

Electrical discharge machine was used to prepare platinum nanocolloid by electric spark discharge method (ESDM) at room temperature. Preparation of platinum nanocolloid needed only traditional electrical discharge machine, platinum wire (99.5%) and magnet mixer. Then verify whether platinum nanoparticles be could successfully prepared under different preparation and their suspension stability. The optical properties and zeta potential were measured by UV–vis and Zetasizer, and their characteristic peaks (surface plasmon resonant), while suspension stability was analysed. The results of transmission electron microscope showed size, shape and dispersibility of platinum nanoparticles with a size of mostly <10 nm. X-ray diffraction was used to measure crystal lattice structure and component of platinum nanoparticles. In this work, platinum nanocolloid in conditions of normal and centrifuge were analysed. Zeta potential of normal colloid was decreased from −29.5 to −18.8 mV after precipitation, while zeta potential of the centrifuged colloid still maintained at −40 mV, confirming the good suspension stability of platinum nanocolloid prepared by ESDM after centrifugation.

In this work, the reduction-responsive hyaluronic acid (HA) coated hollow mesoporous silica nanoparticles (HMSNs) were developed for the targeted tumour therapy. First, the anticancer drug doxorubicin was retained inside the central hollow cavities of the HMSNs with high loading efficiency. Meanwhile, the adamantane group was anchored on the surface of the HMSNs using the disulphide bond as the reduction–cleavable linkage. Subsequently, the β-cyclodextrin (β-CD) decorated HA was immobilised on the surface of HMSNs by the strong β-CD/adamantane host–guest interactions. Specifically, the β-CD acted as the pore caps to block the loaded drug inside, while HA served as the targeting ligand for the effective cancer therapy. Under the intracellular reductive environment, the nanocomposites displayed reduction-triggered drug release manner. Confocal microscopy observations confirmed the nanocomposites were easily internalised by HeLa cancer cells and released the loaded drug inside. In addition, the cytotoxicity study evidenced that HA decorated nanocomposites exhibited improved biocompatibility and antitumour activity as compared to that without HA modification. Thus, the reduction-responsive nanocomposites could be promising as a drug delivery platform toward the cancer therapy.

Different Fe₃O₄ particles are synthesised with silane and carboxylic acid, surface modified by co-precipitation, and subsequently are characterised by Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, laser particle size analyser (LPSA) and thermogravimetric analyser (TG). Based on the LPSA results, Fe₃O₄ particles are micrometre size due to the experimental condition and modifiers. It is therefore suggested that the vacuum freeze-drying and the long-chain modifiers tend to obtain small size particles. The modifiers density on the surface of Fe₃O₄ particles is obtained by TG and formula calculation. It is shown that the silane coupling agent is more effective modifier for Fe₃O₄ particles compared with carboxylic acid. In accordance with the molecular structure and functional group number of carboxylic acids, different carboxylic acids have different modifiers density.

In this work, a simple, efficient and eco-friendly procedure for the green synthesis of manganese dioxide nanoparticles (MnO₂ NPs) by Yucca gloriosa leaf extract is described. The MnO₂ NPs were synthesised using Y. gloriosa leaf extract and curcumin as reducing and stabilising agents, respectively. Fourier-transform infrared spectra revealed the involvement of the plant extract in the formation of MnO₂ NPs. The ultraviolet–visible absorption spectra of the synthesised MnO₂ NPs exhibited absorption peaks at 410 nm, which were attributed to the band gap of the MnO₂ NPs. Crystal phase identification of the MnO₂ NPs was characterised by X-ray diffraction analysis and the formation of crystalline MnO₂ NPs has been confirmed. Also, the X-ray diffraction pattern displayed that the average size of MnO₂ NPs was about 80 nm. Furthermore, field emission scanning electron microscopy analysis showed that the synthesised MnO₂ NPs have a spherical shape. MnO₂ NPs have photocatalytic activities for the dye degradation in the visible light region. The photocatalytic activities for the dye degradation of MnO₂ NPs were evaluated using Acid Orange as an organic contaminant.

A sensitive and fast micro-solid-phase extraction (μ-SPE) coupled with dispersive liquid–liquid micro-extraction (DLLME) was reported before micelle enhanced spectrofluorimetric detection for determination of ciprofloxacin antibiotic in human plasma samples. The DLLME was performed using methanol as disperser and 1-octanol as extracting solvent. Oleic acid-modified Fe₃O₄ nanoparticles (as hydrophobic adsorbents) were applied in μ-SPE step to extract the analyte from DLLME procedure. The method uses the advantageous of high surface area and strong superparamagnetism of these nanoparticles to many avoid labourhood column/cartridge-passing processes of traditional SPE. The major parameters affecting signal enhancement and analyte recovery were evaluated and optimised. Under the optimal conditions, the calibration curve (with calibration equation of I _f = 2.5826 C + 10.273) was linear in the range 0.5–600 μg L⁻¹ (R ² = 0.997) with low limit of detection of 0.21 µg L⁻¹ and limit of quantification of 0.63 µg L⁻¹. The intra-day and inter-day precisions (as relative standard deviation) were in the range of 1.01–1.67% and high recoveries in the range of 93.5–102.4% were obtained. The results demonstrated that the proposed method is easy, low cost, and accurate. In addition, it confirms that choosing extraction solvent was not restricted to the high-density solvents which can extent the versatility of DLLME.

Facile synthesis of silver phosphate (Ag₃PO₄) microcrystals was developed for the novel application in the disinfection of pathogens with visible light. Ag₃PO₄ microcrystals from different synthesis routes were produced and characterised by scanning electron microscopy and UV–visible diffuse reflectance spectroscopy. The antibacterial activity of the Ag₃PO₄ microcrystals was also evaluated for its effectiveness in eradicating pathogens (Escherichia coli and Staphylococcus aureus) under white-light light-emitting-diode irradiation. The prepared Ag₃PO₄ microcrystals displayed higher and more stable photocatalytic antibacterial activity (>99% eradication rate within 10 min) comparing to Ag⁺ ions used only. This can be attributed to the oxidation of the photogenerated hole and the adsorption of Ag⁺ ions. This study demonstrated the strong photocatalytic activity of the as-prepared Ag₃PO₄ microcrystals, promising for industrial applications related to the eradication of pathogens from wastewater.

In the present work, needle-shaped cellulose nanocrystals (CNCs) were prepared from commercial microcrystalline cellulose (MCC) through esterification and ultrasound treatment. The prepared CNCs were characterised by using Fourier transform infrared, degree of substitution (DS), dynamic light scattering, scanning electron microscopy and X-ray diffraction. The results revealed that the ultrasound disintegration of MCC was significantly improved after the esterification with maleic anhydride and the ultrasound treatment did not affect DS of the CNCs. With increasing power of the ultrasound treatment, smaller CNCs with narrower size distribution could be obtained. Average diameter and length of the CNCs could reach ∼14 and ∼180 nm, respectively. Furthermore, the crystal structure of cellulose was not changed during the esterification and ultrasound treatment and crystallinity of the CNCs increased comparing with MCC.

In this study, a novel split-gate lateral double-diffused metal oxide semiconductor field effect transistor with double vertical field plates (SG DVFP LDMOS) is proposed. The first feature of the SG DVFP LDMOS is that the SG with gradient gate oxide is introduced. The SG not only optimises the bulk electric field distributions to increase the breakdown voltage (BV) but also reduces the gate-drain charge (Q _GD) owing to the thick gate oxide. The second feature of the SG DVFP LDMOS is the presence of the DVFP and P-pillar. They modulate the bulk electric field distributions and assist to deplete the drift region. So the specific on-resistance (R _on,sp) is decreased and the BV is improved. The source vertical field plate reduces the contact region between the gate and drain, thereby the Q _GD is reduced. Compared with the conventional SG LDMOS and rectangle-gate DVFP LDMOS, the figure of merit FOM1 of SG DVFP LDMOS is increased by 123.2 and 86.6%, and the loss figure of merit FOM2 is enhanced to 16.9 and 37.2%. Simultaneously, the key process steps of the SG DVFP LDMOS are proposed.

Zinc pollution represents a great environmental risk, particularly with regards to the aquatic environment. In this theoretical contribution, the enhanced solubility of ZnO nanoparticles in pure water is predicted based on a simple thermodynamic model. The study used Zn²⁺, Zn(OH)⁺, Zn(OH)₂, Zn(OH)₃ ⁻ and Zn(OH)₄ ²⁻ as dominant species in aqueous solution and a Gibbs energy minimisation method to calculate equilibrium Zn content in this solution. ZnO was investigated in the form of nanoparticles of various shapes, whose very high surface-to-volume ratio implicates their lower thermodynamic stability compared with bulk material. The interfacial energy of the solid ZnO – dilute aqueous solution interface was assessed by applying the average ZnO surface energy and contact angle of a sessile drop of water on ZnO()-O surface. At 298 K, the ratio of 2 nm spherical ZnO particles to the bulk material solubility was about 23.7. The calculated results were compared with experimental data and yielded a good agreement. These results are not only of great importance for nanomaterials research but they also have implications for environmental protection.

A simple and new solid-state molten-salt method to synthesise silver (Ag)-doped titanium dioxide (TiO₂) nanoparticles for solar light-induced photocatalytic applications is examined. Ag-doped TiO₂ nanoparticles with varied Ag content ranging from 3 to 10% were synthesised by a single-step molten-salt synthesis method. The effect of Ag content on the antibacterial and photocatalytic activity of nanoparticles was tested. The prepared nanoparticles were studied by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectrometry, ultraviolet–visible (UV–vis) diffusive reflectance spectrometer (UV–vis DRS) and powder X-ray diffraction. The SEM image of nanoparticles clearly showed the presence of agglomerated spherical particles. The EDX analysis of the particles confirmed successful doping of particles in the presence of the Ag in the particles. The doping of Ag in TiO₂ produced TiO₂ pure anatase phase. According to UV–vis DRS results, increasing Ag-doped content in the Ag-doped TiO₂ resulted in a higher visible absorption capability of the materials. Ag doping also improved the antibacterial and photocatalytic activity of TiO₂ nanoparticles. The maximum photocatalytic activity under light irradiation was observed for 5% Ag-doped TiO₂.

In this work, in-situ polymerisation of laurolactam in the presence of multi-walled carbon nanotube (MWCNT) was performed toward MWCNT/Nylon12 nanocomposite. Different levels of MWCNT (0.1, 0.3, 0.7, 1.2 and 3.5 wt%) were introduced to the monomer in the presence of 2 wt% toluene diisocyanate and 1 wt% sodium caprolactam as an activator and catalyst, respectively. The test results indicated that by increasing the amount of MWCNT, the conductivity of the nanocomposite increased up to that level at which it could serve as an electrically conductive material at room temperature. The melt rheological measurements showed a transition from liquid-like to solid-like state. The rheological results obtained within the linear viscoelastic region demonstrated that the rheological percolation threshold happened at 0.1 wt% multi-walled nanotube (MWNT), whereas the electrical percolation threshold appeared at 1.2 wt% MWCNT. A homogeneous dispersion of MWCNT into the Nylon12 matrix with a high aspect ratio of MWNT was achieved at a low percolation threshold. This mainly could be attributed to the fact that a denser MWCNT network was required for electrical conductivity, while a less dense MWCNT network sufficiently impeded Nylon12 chain mobility related to the rheological percolation threshold.

The present work emphasises on the synthesis of silver nanoparticles (AgNPs) through the treatment of aqueous solutions of Ag nitrate with commonly available sugars, i.e. sucrose as reducing agents. The average particle size, morphology and elemental composition of the NPs are studied through transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy and ultraviolet–visible (UV–vis) spectroscopic techniques. UV–vis absorption spectroscopy confirms the formation of AgNPs with the strong absorption band at 408 nm. TEM reveals the spherical nature of synthesised AgNPs with a size range of 25–40 nm. Furthermore, catalytic potential of the NPs was examined for reduction of 4-nitrophenol (4-NP) to 4-aminophenol in the alkaline medium by using UV–vis spectroscopy. Complete reduction of the 4-NP was achieved within 35 min, thus validating the efficacy of AgNPs as an efficient catalyst. These catalytic capabilities firmly advocate the applications of AgNPs in the purification of polluted water.

Polylacite (PLA) is a bioresorbable polymer with potential application for bone tissue repair; however, low heat distortion temperature (HDT) limits its biomedical applications. Due to the low-melting point of PLA, only fused deposition modelling (FDM) was used as a rapid prototyping technology to form PLA products. Here, the work presents a PLA stereocomplex formation which was facilitated by melt blending PLA and poly(D-lactide). The melting point was successfully increased to 219.2°C. Besides, the PLA stereocomplex-based three-dimensional scaffold was formed by selective laser sintering (SLS). The parameters of SLS (energy density, scan speed, scan spacing, preheating temperature etc.) were also optimised by comparing the microstructure. Compared with the FDM, the SLS provides many benefits for fabricating tissue engineering scaffolds due to its rough powder surface. Results show that the PLA stereocomplex was successfully obtained and crystallinity of the stereocomplex was 59.7%.

In this work, the authors have focused on increasing the current driving capability, speed of operation, suppression of parasitic capacitance and ambipolarity of the charge plasma tunnel field effect transistor (CPTFET). Gate dielectric and hetero-material engineering are employed in the CPTFET to obtain better drain current. Introduction of high-k dielectric increases the injection of charge carriers in the intrinsic body while a low-energy bandgap III–V material reduces the tunnelling width leading to the increased rate of band-to-band tunnelling of electrons and thus, enhancing the ON-state current of the device. Hence, the proposed device shows superior performance when operated in regime of DC and high frequency. For reducing the ambipolar conduction in the device, a widely used concept of underlapping of gate electrode is employed which reduces the leakage current in the device. Further, to determine the reliability of the device at high frequency, an analysis of linearity parameters is carried out. The proposed device is highly reliable to function at high-frequency regime. Therefore, the overall introduction of gate dielectric engineering, hetero-material engineering and underlapping of gate electrode improves the performance and characteristics of CPTFET.

Through designing dispersed well and assembled orderly structures, a series of polyaniline (PANI)/carbon (CB) microcapsules were successfully synthesised. In the formation of the PANI/CB microcapsules, PANI/CB microcapsules were in good dispersion and ordered state, which resulted in exceptional mechanical properties and electrical conductivity for polytetrafluoroethylene (PTFE)/glass fabric (GF) composites. Here, the authors have developed the PTFE/GF composites that have not only tensile strength up to 21.5 MPa, but also toughness up to 17.5 MJ/m³, and surface resistivity up to 5 × 10⁸ Ω cm, it is difficult to obtain by other methods. This was achieved by only assembled orderly and ordered arrangement for forming highly ordered network structures in an oriented direction, without introducing a third component or chemical cross-linker as in interfacial systems. More importantly, they believe that the design principles and processing strategies, which can be applied to other material systems to develop superconducting, strong and flexible materials.

Two-dimensional (2D) non-polarising transmission filters based on guided-mode resonance (GMR) for the optical communication wavelength O-band and C-band have been designed and fabricated. This type of GMR filter (GMRF) is composed of a 2D metal grating layer, a waveguide layer, and a glass substrate. The rigorous coupled-wave analysis is used to calculate the transmission spectra of the designed GMRFs. The grating structures of the GMRFs are patterned by electron beam lithography. The transmission spectra of the fabricated GMRF samples at different incident angles are measured by rotating a motorised stage and the experimental results agree closely with the theoretical designs. The measured results show that the transmission spectra of the two GMRF samples are insensitive to the incident angle. A deviation of 1° in the angle of incidence from normal illumination does not lead to the reduction of the peak transmittance. Although a narrow secondary resonance appears at oblique incidence for transverse-magnetic polarisation, the resonance spectral shapes for transverse-electric polarisation and TM polarisation are nearly identical at incident angles of 0–1.5°. Compared to previous reported non-polarising GMRFs, the angular tolerances of the fabricated samples are remarkably enhanced.

A piezoelectric nanowire is used to adjust the resonant frequencies of nanoscale beams in a magneto-thermal environment. For tuning purposes, an external electric voltage is applied to the piezoelectric nanowire. Eringen's non-local theory of elasticity is employed to capture length scale effects. Based on the Timoshenko beam theory in conjunction with the Pasternak model and non-local piezoelasticity, the scale-dependent partial differential equations of the smart nanoscale system are derived. An exact solution procedure is proposed for the frequency tuning of nanobeams with simply supported boundary conditions. Furthermore, the frequency response of the piezoelectric nanosystem with different boundary conditions is analysed with the help of the differential quadrature method as an efficient numerical approach. It is found that the thickness of the piezoelectric nanowire, the temperature change, the longitudinal magnetic field and the applied electric voltage can be exploited in a careful way in order to adjust the resonant frequency of nanobeams.

This is the first report on 3D sinusoidal Bragg grating structure based on hybrid metal insulator metal (HMIM) plasmonic waveguide. The proposed structure has a gradual change in the refractive index rather than an abrupt change providing excellent filtering characteristics. The device is studied at an operating wavelength of 1.55 μm. The results are based on numerical simulations performed using the software CST microwave studio suite. The transmission characteristics show more than 80% transmission in the passband and near zero transmission in the rejection band. The proposed structure reduces the scattering losses and a wide bandgap of 0.387 μm is achieved. The proposed structure has a track length of 3.784 μm for 11 cells, which is very less compared to previous reports allowing large-scale integration of photonic devices. A microcavity is also formed and its resonance is investigated by introducing a defect length of 0.217 μm in the periodic structure. A peak transmission of 50% and a narrow resonance bandwidth of 0.029 μm are achieved at 1.55 μm resonance wavelength. The quality factor which defines the energy stored in the cavity is Q = 53.