Showing papers in "Micro & Nano Letters in 2019"

Green synthesis and characterisation of ZnMn2O4 nanoparticles for photocatalytic degradation of Congo red dye and kinetic study

Abstract: In this work, ZnMn2O4 spinel nanoparticles were successfully synthesised by tragacanth gel through the easy and inexpensive novel sol–gel method. This technique has many strong points such as facile, economical, non-toxic and quickness in comparison with other methods. The zinc manganite nanoparticles were characterised by X-ray powder diffraction (XRD), transmission electron microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and diffuse reflectance spectroscopy. The XRD pattern confirmed the formation of spinel tetragonal structure of ZnMn2O4 nanoparticles with a crystallite size of 14 nm. The degradation of Congo red dye by synthesised nanoparticles was studied using employing UV–Vis spectroscopy. The ZnMn2O4 NPs expressed high photocatalytic activity for degradation of Congo red dye at room temperature in aqueous solution so that 96% of Congo red was degraded in 15 min. The spinel ZnMn2O4 photocatalyst provided total organic carbon removal as 45.2% in 15 min. The spinel ZnMn2O4 NPs reusability was examined by administering the degradation of Congo red dye with the spent catalyst and it was considered that the photocatalyst did not exhibit any significant reduction in its activity even after three cycles.

Approach to suppress ambipolar conduction in Tunnel FET using dielectric pocket

Abstract: The impact of high- k dielectric pocket (DP) on the ambipolar conduction of tunnel field-effect transistors (TFETs) is demonstrated using two-dimensional Technology Computer Aided Design (TCAD) simulations. In the proposed structure of TFETs, an optimised portion of the upper drain region is replaced with a high- k DP at the channel-drain interface. It is demonstrated that due to the enhancement of the depleted drain region under DP, the minimum tunnelling width at channel-drain interface increases, and attains a maximum value for an optimum length and thickness of DP. Eventually, this increment in the minimum tunnelling width leads to a significant reduction in ambipolar conduction in TFETs. Furthermore, it is shown that performance parameters including the ON-state current, subthreshold swing and output characteristics are not affected by the presence of the proposed DP. Even, the gate-to-drain capacitance is reduced with the inclusion of DP at the channel-drain interface, thus leading to an improved cut-off frequency of TFETs. Moreover, it is also demonstrated that only a 10 nm of gate-on-drain overlapping along with this DP is capable of eliminating the ambipolarity completely for even a higher gate voltage of -0.8 V.

Biological synthesis of silver nanoparticles by cell-free extract of Polysiphonia algae and their anticancer activity against breast cancer MCF-7 cell lines

Abstract: Green nanomaterial production techniques are desired for medicinal applications because of their biocompatibility and lack of toxic by-products. This work reports the biological synthesis of silver nanoparticles (AgNPs) from silver nitrate solutions using the cell-free extract of Polysiphonia alga as a reducing agent. The visible yellow-brown colour formation and surface plasmon resonance at 420 nm by ultraviolet–visible spectroscopy indicates the reduction of silver nitrate and biosynthesis of AgNPs. For more characterisation of green synthesised AgNPs, Fourier-transform infrared (FTIR) spectroscopy analysis is used and the results confirmed the presence of functional groups capping in the AgNPs. The scanning electron microscopy and transmission electron microscopy images showed mostly spherical AgNPs with a size range between 5 and 25 nm and the concentration of 3.1 × 106 particles/ml. The results of energy-dispersive X-ray analysis confirmedthe presence of Ag in the synthesised nanoparticles. The MTT assay and flow cytometry are used to determine the toxicity of AgNPs against breast cancer MCF-7 cell line and the results showed the best inhibitory activity at 100 µg/ml. Generally, green synthesis of anticancer AgNPs using filamentous red alga Polysiphonia extract can easily be scaled up for many biomedical applications such as defence against the cancerous cells.

Ultrathin colloidal crystal layer as transparent photonic films

Abstract: The study employed a facile approach to fabricate a large-area ordered robust colloidal crystal films. Poly(methyl methacrylate) colloids were dispersed and self-assembled in poly(vinyl alcohol) solution, which was then cured to form a photonic film. Such films efficiently diffract electromagnetic waves of specific wavelengths, and whose photonic band gap could be tuned from ultraviolet to visible region by changing the size of the colloids. The presented films revealed sharp diffraction and high transparency, indicating the promising applications in coating or colour filter materials.

Simultaneous adsorption of Hg2+, Cd2+ and Cu2+ ions from aqueous solution with mesoporous silica/DZ and conditions optimise with experimental design: kinetic and isothermal studies

Abstract: This study used dithizon (DZ) and mesoporous as a sorbent for simultaneous removal of heavy metal (mercury, cadmium and copper) ions from aqueous solution and real samples. Santa Barbara Amorphous synthesised and characterised by X-ray diffraction, Fourier-transform infrared spectroscopy and Brunauer–Emmett–Teller. Heavy metal ions measured by atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry. Optimised conditions such as pH, removal time, sorbent dosage and concentration analyte with central composite design and obtained 5, 20 min, 20 mg and 25 ppm, respectively. The equilibrium data were fitted to isotherm models such as Langmuir, Freundlich and Tempkin and the results revealed the suitability of the Langmuir model. The maximum adsorption capacities for Hg2+, Cd2+ and Cu2+ ions achieved 25.04, 30.3 and 31.79 mg/g, respectively. Kinetics data fitting to pseudo-first order, pseudo-second-order and Elovich models confirmed the applicability of pseudo-second-order kinetic model for the description of the mechanism and adsorption rate. This sorbent could regenerate easily with ethylenediamminetetraacetate solution.

Applications of micro–nano bubble technology in environmental pollution control

Abstract: Owing to some advantages of high oxidation capacity, high mass-transfer efficiency, high utilisation rate of reagents, simple system for treating pollutants, micro-nanobubble technology (MNBT) has gradually attracted attention and has been successfully applied in environmental pollution control. Currently, its applications in this field are mainly in the aspects of surface water purification, sewage (waste) water treatment, soil and groundwater remediation and sludge treatment which are reviewed. These studies primarily focus on the MNB generation (MNBG) methods, the parameters of pollution treatment and its effect improvement, the coupling techniques of this technology and other advanced oxidation technologies. However, in order to successfully promote its applications to the actual environmental pollution control process, especially the industrial scale, the following efforts are required: covariant response mechanism of water quality - micro-nano aeration parameters - bubble characteristics, further optimisation of synergistic process with other advanced oxidation methods, development of lower energy consumption and more efficient MNBG devices. After discussion and analysis, this work further points out that the purification of exhaust gas such as volatile organic compounds (VOC) and flue gas is one of the research directions worth exploring in the future application of the MNBT.

Optimisation of pocket doped junctionless TFET and its application in digital inverter

Abstract: In this work, a device called pocket doped junctionless tunnel field-effect transistor (JL-TFET) for digital inverter application is proposed. The operation of this device is subjected to junctionless technique and initially it has an N+-N+-N+ structure. This device utilises a SiGe N+ pocket at the source side and a dual gate namely, fixed gate and control gate. By keeping the fixed gate voltage below its flat band voltage and varying the control gate from 0 to V DD , the device is converted from the N+-N+-N+ structure to P-I-N structure and operates like a tunnel field-effect transistor (TFET). The inclusion of N+ pocket gives an additional tunnelling path perpendicular to the gate-oxide thickness. A brief examination of the proposed device has been done on the impacts of the work-function variations of both the gate metals. A subthreshold swing of 43.6 mV/dec is obtained for fixed and control gate work-function of 5 and 4.5 eV, respectively. The proposed device gives the drain current of 5.7 × 10 -4 A approximately twice that of conventional JL-TFET. Further, an radio frequency analysis of the device is done for different parameters such as drain current ( I D ), total gate capacitance ( C gg ), transconductance ( g m ) and cut-off frequency ( f T ) and the outcomes are compared with conventional JL-TFET. The device is found to be suitable for high-frequency application. Lastly, it is applied on inverter circuit and its voltage transfer characteristics are studied.

Investigation of RF and linearity performance of electrode work-function engineered HDB vertical TFET

Abstract: This work realises a hetero-dielectric buried oxide vertical tunnel held effect transistor (HDB VTFET) and investigates its radio frequency (RF) and linearity characteristics. First time, the concept of hetero-dielectric buried oxide (BOX) in VTFET is used to obtain the superior improvement in terms of different RF and linearity hgure of merits such as C gs , C gd , C gg , f T , Gain Bandwidth Product (GBP), t, Transconductance Frequency Product (TFP), Transconductance Generation Factor (TGF), g m2 , g m3 , VIP 2 , VIP 3 , IIP 3 , IMD 3 and 1-dB compression point. Also, the influence of HfO2 BOX length scaling on these FOMs is analysed. The results reveal that the HDB VTFET can be a promising contender to replace bulk metal-oxide semiconductor held-effect transistors in analogue/mixed signal system-on-chip and high-frequency microwave applications and the accuracy of this device is validated by TCAD Sentaurus simulator.

Two-dimensional functionalised methacrylated graphene oxide nanosheets as simple and inexpensive electrodes for biosensing applications

Abstract: Biosensors based on immobilised enzyme propose determination of analytes with excellent selectivity and sensitivity while their stability is still a challenge. Thus, promoting the selective, sensitive, rapid, inexpensive, and reliable strategies to fabricate new biosensors is a critical issue for the analyte determination. In this study, a novel functionalised graphene, methacrylated graphene oxide (MeGO), was utilised as an advanced biosensing device for non-enzyme determination of ascorbic acid (AA). The MeGO-based sensor was fabricated by a very simple coating approach on a glassy carbon electrode. The cyclic voltammogram of the new biosensor demonstrated a pair of well defined, reversible, and stable peaks for redox systems in a buffer solution. The exploited nanobiosensor depicted high catalytic bioactivity towards the oxidation of AA at a positive potential in the buffer solution. The biosensing characteristics of the developed nanobiosensor presented excellent sensitivity, low limit of detection, and wide linear range. To the best of this study's knowledge, this is the first research that uses MeGO in biosensing applications. Moreover, the sensing characteristics of the device are compared with other developments previously reported for non-enzyme AA sensors.

Effects of rotational restraints on the thermal buckling of carbon nanotube

Abstract: The thermal buckling response of nanotubes with rotational restraints is investigated using a Timoshenko beam model with non-local elasticity theory. Two trigonometric (Fourier) series are selected to analyse the thermal buckling of the non-local Timoshenko nanotube with rotational restraints. Explicit equations are obtained for the boundary values with a coefficient matrix. In particular, the new method can be degenerated to the non-local Euler beam model by assigning proper value to the shear correction factor. The main advantage of the present technique is its capability of dealing with deformable or rigid supporting conditions. Several numerical examples are solved to asses proposed approach reliability. The results show that thermal buckling including the thermal effects are lower than those without the thermal effects when the temperature rises. The rotational restraint springs have significant effects on the buckling response of nanotubes.

Multi-walled carbon nanotube films for the measurement of the alcoholic concentration

Abstract: The work shows that a multi-walled carbon nanotube (MWCNT) film can be used as the sensing element of a low-cost sensor for the alcoholic concentration in liquid solutions. For this purpose, they investigate the electrical resistance of the film as a function of the isopropanol concentration in a water solution. The analysis reveals a growing resistance with increasing isopropanol concentration and a fast response. The sensing element is re-usable as the initial resistance value is restored once the solution has evaporated. The electrical resistance increases linearly when the MWCNT film is exposed to common beverages with increasing alcoholic content. This work paves the way for the development of low-cost, miniaturised MWCNT-based sensors for quality monitoring and control of alcoholic beverages and general liquid solutions.

Development of hot embossing setup and fabrication of ordered nanostructures on large area of polymer surface for antibiofouling application

Abstract: Nanostructured polymeric film has wide range of applications in different fields. However, the existing processes of fabrication of nanostructures on polymer surfaces are limited to very small area and throughput of the processes is very low. In order to solve this challenge, the indigenous hot embossing setup was developed which is capable of patterning micro-nano structures on large area. In this work, the steps for the development of hot embossing setup are discussed. The setup requires nanostructured mould, copper-chromium block, pencil heaters and temperature controlled system (thermostat and thermocouple). Two different types of nanostructures (groove and pillars) were successfully replicated on polystyrene film. The fabricated nanostructures were characterised using field emission scanning electron microscope and atomic force microscope. The dimensions of fabricated nanostructures are close to the mould dimensions with few defects (shrinkage defects). The wettability test was performed using goniometer on plain and structured polystyrene film to study the effect of structures on the wettability of the surface. It was observed that the hydrophilic (water droplet contact angle: 43°) polystyrene film got converted into hydrophobic (water droplet contact angle: 102-112°) nature. The fabricated structured surfaces have shown antibiofouling property which was confirmed through plate counting method.

Characterisation of a bis-ferrocene molecular QCA wire on a non-ideal gold surface

Abstract: Field-coupled nanocomputing represents one of the possible proposals for the post-Complementary Metal Oxide Semiconductor (CMOS) scenario Contrarily to standard technology, the information is not propagated using electron transport, but via field interactions among single elements The molecular quantum-dot cellular automata (QCA) is one of the most promising implementations; redox centres of oxidised molecules are used to concentrate charges Coulomb interaction between redox centres enables the information propagation The necessity for charge transport is overcome, entailing very low power consumption notwithstanding the nanometric size and the very high expected operating frequency Nevertheless, as the Coulomb interaction strongly depends on the distance between charges, the position of each molecule plays a relevant role in the interaction This work investigates the information propagation of a possible molecular wire thiolated on a non-ideal gold surface, where the intermolecular distance may vary due to the surface roughness and possible defects introduced in the formation of the molecular wire The efficiency of the information transfer is analysed with the aim of providing significant constrains and suggestions for future fabrication steps

Development of strain energy harvester as an alternative power source for the wearable biomedical diagnostic system

Abstract: The human body is considered as a rich source of energy in the forms of body motion, heat etc. These energies can be trapped to develop a viable energy source, which confines the long-term serviceability. The battery drove wearable systems suffer from critical issues such as weight, limited lifespan and lack of biocompatibility. It is the main hurdle in gaining market acceptance for wearables. Rapid growths of wearable for biosensing motivate them to use it for health monitoring. This work describes the complete fabrication flow for low-cost energy harvesting device as an alternative power source for wearable biomedical diagnostic system with prime focus on biocompatibility, deformability and conformability. The conversion of body motional energy into electrical energy is carried out using zinc oxide piezoelectric material, polydimethylsiloxane substrate and silver fabric electrodes. The estimated power demand of the biomedical sensing modules lies in the range of 1–100 μW. It is observed that optimum power can be harvested when the device is placed between socks fabric and foot sole. The power level of 106 µWpeak or 22 µWrms has been recorded which reveals the feasibility as an alternative power source.

Green synthesis of ZnO/SiO2 nanocomposite from pomegranate seed extract: coating by natural xanthan polymer and its characterisations

Abstract: This work presents a simple, economical and, importantly, green process to develop a nanocomposite (NC) that covers the functions of surfactant and polymer flooding in enhancing oil recovery (EOR). Thus, xanthan coated ZnO/SiO 2 NC was prepared using the extract of the pomegranate seeds as a reducing and stabilising agent. The green synthesised NC was identified using the scanning electron microscopy, electron dispersive spectroscopy, elemental mapping, X-ray diffraction, and UV–vis analytical techniques. ZnO/SiO 2 /Xanthan NC was then dispersed in low-salinity water (1:20 diluted seawater) at different concentrations, and high suspension stability of NC was observed at different periods of time. This investigation provides a novel and green pathway for preparing nano-EOR fluids.

Fabrication and improvement of PCL/alginate/PAAm scaffold via selective laser sintering for tissue engineering

Abstract: In this work, porous polycaprolactone (PCL) scaffolds were designed and fabricated using selective laser sintering (SLS) The critical processing parameters of the SLS for PCL were optimised This work post-processed these PCL scaffolds to produce PCL/alginate/polyacrylamide (PAAm) scaffolds to improve their performance The experiment mechanical property assessment showed that the sample's average elastic modulus increases from 699 MPa (PCL) to 1267 MPa (PCL/alginate/PAAm), and the elongation at break of samples increases from 59% (PCL) to 1129% (PCL/alginate/PAAm) Cell seeding and in vitro culture showed that cell viability remained above 94% over 5 days Thus, the current study suggests that a promising strategy for the improvement of the characteristics of PCL/alginate/PAAm scaffolds and advances the potential application of SLS technique towards skeletal tissue repair

Linearity improvement in E-mode ferroelectric GaN MOS-HEMT using dual gate technology

Abstract: In this work, an enhancement mode dual gate ferroelectric gallium nitride metal oxide semiconductor-high electron mobility transistor (GaN MOS-HEMT) is proposed with enhanced linearity characteristics. The different DC characteristics of the device are analysed and compared with available experimental data of single gate un-recessed ferroelectric GaN MOS-HEMT. In order to analyse the linearity performance of the devices, a look up table-based large signal model is developed directly from technology computer-aided device simulation results built by feeding different small signal parameters. The different linearity characteristics such as input third-order intercept point (IIP3), the input gain compression point (P1dB), third-order intermodulation (IM3) and the carrier to intermodulation power ratio of both the devices are compared by harmonic balance simulation of the developed large signal models. The interlink between IIP3 and IM3 with transconductance indicates that the broader the transconductance distribution with respect to different gate voltage generates higher IIP3 and lower IM3, which results in an improved linearity performance. The dual gate device shows improved linearity performance resulting in applicability in radiofrequency front end receiver.

Understanding the performance of gamma-ray-irradiated epoxy nanocomposites

Abstract: Epoxy nanocomposites being used in the high-energy radiation zones as an insulant may undergo changes in their dielectric properties during service. In the present study, the performance of base epoxy resin (S1) is compared with epoxy resin with ion trapping particle (Sample S2) and epoxy resin with nanotitania (Sample S3) particle. The influence of gamma irradiation on nanocomposites was analysed. Corona inception voltage due to water droplet initiated discharge and contact angle reduces post-gamma-ray irradiation. Surface potential decay time constant reduced drastically for gamma-ray-irradiated specimens. Trap distribution characterisation indicated that charge mobility increases after irradiation. The surface roughness of the sample increases with the irradiation dosage. Dielectric relaxation spectroscopy shows that permittivity reduces and loss tangent increases with the gamma-irradiated specimens. Water diffusion rate increases for the gamma-ray-irradiated specimen. No change in elemental composition, measured using laser-induced breakdown spectroscopy, of test specimens was observed. The hardness of the material and plasma temperature formed during laser shine decreases with gamma-ray irradiation intensity for Sample S1, whereas samples S2 and S3 showed only marginal variation. The performance of Sample S2 is found to be better than Samples S1 and S3.

Effect of gamma irradiation on space charge and charge trap characteristics of epoxy–MgO nanocomposites

Abstract: Insulating materials used in power apparatus required to be space charge free. Epoxy–magnesium oxide (MgO) nanocomposites were prepared and gamma rays were irradiated for different dosages to understand the dielectric parameters variation, space charge characteristics, surface potential variations, and for getting charge trap characteristics of the material. It is realised that permittivity increases and then reduces when the irradiation level is increased. Tan (δ) marginally increased with increasing dosage of gamma irradiation. Space charge accumulation reduces with increase in wt% of MgO in epoxy resin. 3 and 5 wt% MgO added samples showed stable space charge accumulation and fast decay during depoling, irrespective of irradiation level. Surface potential decay time reduces with irradiated specimens. After irradiation, epoxy nanocomposites showed both shallow trap formation and deep trap formation and found that shallow trap density is high compared to the deep trap density. All the irradiated specimens showed a decrease in the trap energy level compared to the virgin specimens.

Study on the performance of temperature-stabilised flexible strain sensors based on silver nanowires

Abstract: Nowadays, flexible strain sensors applied in the fields of health care and electronic skin have been widely studied and applied. In fact, the temperature characteristic of flexible strain sensors based on metal nanomaterials is rarely concerned. In this work, the ohmic and tensile properties of the flexible strain sensor based on silver nanowires–polydimethylsiloxane were tested and it was found that the sensor has good ohmic characteristics and a maximum gauge factor of 536.98. In addition, the resistance of the sensor was affected little by temperature when the temperature environment of the sensor was changed, and the resistance temperature coefficient of the flexible strain sensor is −1050 ppm/°C. Furthermore, it was found that the sensor was sensitive to minute strain when the sensors were applied to the two application tests of strain and pulse.

Thin-film transistors based on wide bandgap Ga2O3 films grown by aqueous-solution spin-coating method

Abstract: Ga2O3 is a wide bandgap oxide semiconductor material with the bandgap value only second in magnitude to diamond among known semiconductors. As a wide-bandgap semiconductor, Ga2O3 has emerged as a new competitor to silicon carbide and III-nitrides in various applications of ultraviolet optoelectronics and high power electronics. However, almost all the devices are based on the Ga2O3 grown by molecular-beam epitaxy or chemical vapour deposition, which is time-consuming and expensive. In this work, the authors report on thin-film transistors based on wide bandgap Ga2O3 films grown by aqueous-solution spin-coating method. The morphological, optical and electrical properties of the films and devices are investigated using a range of characterisation techniques, whilst the effects of post-deposition annealing are also investigated. Both as fabricated and post-annealed Ga2O3 films are found to be very smooth and exhibit wide energy bandgaps of around 4.8 and 4.9 eV, respectively. Thin-film transistors based on the grown Ga2O3 films show n-type conductivity with the maximum electron mobility of 0.1 cm2/Vs.

Toxicity, morphological and structural properties of chitosan-coated Bi2O3–Bi(OH)3 nanoparticles prepared via DC arc discharge in liquid: a potential nanoparticle-based CT contrast agent

Abstract: In this study, Bi 2 O 3 nanoparticles were employed as computed tomography (CT) contrast agents. In this regard, X-ray attenuation of Bi 2 O 3 nanoparticles, prepared via DC arc discharge in water, was investigated. In addition, the optical, structural, morphology and cytotoxicity properties of afforded nanoparticles were also studied. The electric arc discharge was done via bismuth electrodes in a water medium. Then, to stabilise Bi 2 O 3 nanoparticles, chitosan molecule was cross linked via glutaraldehyde around Bi 2 O 3 nanoparticles. X-ray diffraction analysis demonstrated the monoclinic structure and field emission-scanning electron microscopy images clarified the average size of Bi 2 O 3 as 40 nm. Fourier transform infrared analysis proved chitosan band formation around Bi 2 O 3 nanoparticles. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed no considerable toxicity after 72 h. Finally, X-ray CT of chitosan-coated Bi 2 O 3 nanoparticles and Iohexol was carried out at concentrations of 1-6 mg/ml. The CT number of chitosan-coated Bi 2 O 3 nanoparticles measured 16, 30, 49, 66, 75 and 85, as well as, respective numbers for Iohexol were 5, 14, 25, 34, 44 and 57. Therefore, it displayed that X-ray attenuation of chitosan-coated Bi 2 O 3 nanoparticle was more in comparison with Iohexol at the same concentrations. Eventually, the results demonstrated that chitosan-coated Bi 2 O 3 nanoparticles are a suitable candidate for commercial iodine contrast agent substitution.

Biomolecules encapsulated TiO2 nano-cubes using Tinospora cordifolia for photodegradation of a textile dye

Abstract: In the present research work, novel nano-sized cubes of TiO 2 capped with the biomolecules of Tinospora cordifolia leaf extract have been successfully synthesised and characterised. UV-visible absorption spectrum shows the maximum absorption edge at a wavelength of 271 nm. Transmission electron microscope results reveal the development of nano-sized cubes with anatase phase confirmed from selected-area electron diffraction pattern. Further, X-ray diffraction study re-confirms the crystallinity and anatase phase evolution of TiO 2 . Fourier transmission infrared and energy-dispersive X-ray spectrum spectra elucidate the presence of biomolecules on TiO 2 surface. The high photocatalytic activity of green synthesised TiO 2 is demonstrated through the degradation of a textile dye, neutral red. A total 93.4% of dye has been removed with high apparent constant value ( K appa = 0.00758 min -1 ) under 120 min of short UV-light irradiation. Therefore, current work presents simple, low-cost, eco-friendly and hitherto unreported synthesis of TiO 2 nano-cubes using Tinospora cordifolia leaf extract that could pave the way towards highly efficient photocatalysts.

Dielectric and thermal properties of micro/nano boron nitride co-filled EPDM composites for high-voltage insulation

Abstract: Ethylene propylene diene monomer (EPDM) is a polymeric material widely used for high-voltage insulation. This work reports the dielectric and thermal properties of EPDM co-filled with micro- and nano-BN particles. EPDM composite samples with different micro and micro/nano co-filled contents are prepared by melt-blending and followed by hot press application. Measurements were made including broadband dielectric spectroscopy, thermogravimetric analysis and thermal conductivity. Experimental findings indicate that Micro-25 wt% + Nano-5 wt% performs better in terms of dielectric loss and conductivity whilst the dielectric constant is measured lower in Micro-29 wt% + Nano-1 wt% relative to the equivalent micron filled Micro-30 wt%. Moreover, the initial degradation temperature and final residual masses of co-filled composites are found considerably higher. The thermal conductivity of EPDM is highly influenced by the introduction of co-filled set of particles and it is measured about 0.465 W/m.K in Micro-29 wt% + Nano-1 wt% which is 18% higher than Micro-30 wt%. It is likely that the denser packing geometry due to co-filled set of particles inside the EPDM matrix improves the dielectric and thermal properties which make such composites more attractive for electrical insulation applications.

Mesoporous structure TiO 2 /SiO 2 composite for methylene blue adsorption and photodegradation

Abstract: In this work, a mesoporous structure TiO 2 /SiO 2 (M-TS) composite with excellent adsorption and photocatalytic properties was fabricated by a sol-gel process combined with calcination. The structure of the samples was characterised by scanning electron microscopy and Brunauer-Emmett-Teller analysis. The factors influencing the adsorption behaviours of methylene blue (MB) onto M-TS, including ingredient, dosage, initial concentration and temperature were investigated. The M-TS was produced by removing poly(vinylpyrrolidone) from the precursor gel was vital to the excellent adsorption capacity. Furthermore, the isotherm and kinetic data were fitted by using Langmuir and Freundlich isotherm models, pseudo-first-order and pseudo-second-order equations, and the intra-particle diffusion model. The Langmuir isotherm model and the pseudo-second-order kinetics were the most suitable models for describing the adsorption of MB onto M-TS. It was also found that the adsorption capacity of cationic dyes on M-TS is better than that of anionic dyes. The experimental results of adsorption and photodegradation proved that improvement of adsorption capacity enhances the decolourisation efficiency. This work shows that the M-TS could be used as an effective adsorbent and photocatalyst to remove cationic dyes from wastewater.

Plasmonic nano bow-tie arrays with enhanced LSPR refractive index sensing

Abstract: In this work, the performance of the nano bow-tie arrays for biosensing applications has been investigated. Since the geometrical parameters of the device such as the bow-tie length and gap size have major effects on the system's optical response, a parametric study based on finite-difference time-domain (FDTD) method has been conducted. In order to enhance the sensitivity, two bow-tie shaped nanoparticles in the form of 2 × 1 and 2 × 2 arrays have been developed. In the case of TM polarisation, a sensitivity up to 923 nm/RIU with a figure of merit (FOM) of 5.5 has been obtained for 2 × 2 nano bow-tie array. Moreover, the performance of the proposed nanoparticles for TE polarisation has been evaluated and a FOM exceeding 15.9 has been achieved for single nano bow-tie. According to this study, the proposed nano bow-tie structures have a great potential for sensing and detection applications.

Separation and characterisation of montmorillonite from a low-grade natural bentonite: using a non-destructive method

Abstract: Bentonite clays containing mostly montmorillonite as a nanostructure group of smectite have been used as industrial raw material in many applications. The presence of the other impurities in bentonite clays reduces the value of bentonite. Therefore, the bentonite purification is necessary. In this research, the purification and separation of montmorillonite from a low-grade natural bentonite were considered on the regular and comprehensive plan. For this purpose, a set of methods including dispersion, sodium-activation, sedimentation, sonication and centrifugation were used. In contrast to many methods, there were often complex, expensive and non-effective; this purification method was found to be effective for removing almost all quartz, carbonates and clinoptilolite as the major impurities. In this purification method, the montmorillonite content was increased from 15 to 84% with the separation yield of 80%. The influence of centrifugal force and the type of ultrasonication indicated the most critical parameters in the purification yield, the physical properties and the crystalline structure of the final products. The laser particle size distribution analysis, X-ray diffraction, semi-quantitative analysis and Fourier-transform infrared spectroscopy results showed the decrease of impure phase without any structural changes or damages in clay framework.

CTAB assisted co-precipitation synthesis of NiO nanoparticles and their efficient potential towards the removal of industrial dyes

Abstract: In this work, nickel oxide nanoparticles (NiO NPs) have been synthesised via cost-effective and highly convenient co-precipitation method, using cetyl trimethyl ammonium bromide (CTAB) as capping agent and NaOH as a reducing agent. The as-synthesised NPs have been analysed by a number of spectroscopic and microscopic techniques such as UV–visible spectroscopy, transmission electron microscope, X-ray diffraction, Fourier transformed infrared and energy dispersive X-ray. The prepared NiO NPs hold the prodigious potential towards the photocatalytic degradation of reactive blue 81 and Coomassie brilliant blue R-250 dyes with degradation efficiency of 90.8 and 95.7% and have high dye degradation rate constants of 1.3 × 10 − 2 min − 1 and 2.2 × 10 − 2 min − 1, respectively. Thus, this work signifies an efficient way to employ the NiO NPs as effective photocatalyst towards the alleviation of noxious industrial dyes.

Glucose biosensor using fluorescence quenching with chitosan-modified graphene oxide

Abstract: A novel graphene oxide (GO) nanomaterial, which was rapidly and simply synthesised and conjugated with low-molecular-weight chitosan (CS), was used to develop a simple, sensitive GO biosensor system for glucose detection by fluorescence resonance energy transfer. The GO-CS was used to detect low concentrations of glucose based on competitive binding with maltose-binding protein (MBP). The α-subunit of recombinant phycocyanin (rPC), which emits far-red fluorescence, was used to label MBP (MBP-rPC). The rPC emission was quenched by binding between GO-CS and MBP. However, in the presence of glucose, GO-CS was out-competed for binding to MBP, leading to rPC fluorescence. Glucose was sensitively and selectively detected with this biosensor, with a linear detection range of 0.1-1 mg glucose/ml. The limit of detection for glucose was ~0.05 mg/ml.

Si/SiC heterojunction lateral double-diffused metal oxide semiconductor field effect transistor with breakdown point transfer (BPT) terminal technology

Abstract: A novel silicon (Si) on silicon carbide (SiC) lateral double-diffused metal oxide semiconductor field effect transistor with deep drain region is proposed. Its main idea is transferring the breakdown point and utilising the high critical electric field of SiC material to suppress the curvature effect of the drain, which eventually alleviates the trade-off relationship between breakdown voltage (BV) and specific on-resistance ( R on,sp ). Through the TCAD simulation, the results show that the BV is significantly improved from 240 V for conventional Si lateral double-diffused metal oxide semiconductor (LDMOS) to 384 V for the proposed structure with the drift region length of 20 μm, increased by 60%. The figure-of-merit of the conventional Si LDMOS and the Si/SiC LDMOS are 2.04 and 4.26 MW/cm 2 , respectively. It indicates that the proposed structure has better performance than the Si counterpart. The influences of design parameters and interfacial charges on the device performance are also discussed in this work.