Showing papers in "Journal of Nano Research in 2020"

MHD Hybrid Cu-Al2O3/ Water Nanofluid Flow with Thermal Radiation and Partial Slip Past a Permeable Stretching Surface: Analytical Solution

Abstract: The influence of velocity slip and thermal radiation effects on the magnetohydrodynamic hybrid Cu-Al2O3/water nanofluid flow over a permeable stretching sheet is reported in this paper. The similarity transformation is adopted to reduce the partial differential equations to the ordinary differential equations. Exact analytical method is implemented to solve the problem. Maple program is used to facilitate the calculation process. The new additional effects which are the velocity slip and thermal radiation effects are considered towards the model to scrutinize the impacts. The effects of various parameters towards the velocity and temperature profiles are demonstrated through graphs, meanwhile the skin friction coefficient and the local Nusselt number are exhibited through the tabulation of data. The existence of velocity slip reduced the velocity profile but enhanced the temperature profile. The thermal radiation effect has increased the temperature profile. The heat transfer rate are enhanced for the case of hybrid nanofluid compared to the mono nanofluid.

Critical Buckling Load of Triple-Walled Carbon Nanotube Based on Nonlocal Elasticity Theory

Abstract: The present paper investigates the nonlocal buckling of Zigzag Triple-walled carbon nanotubes (TWCNTs) under axial compression with both chirality and small scale effects. Based on the nonlocal continuum theory and the Timoshenko beam model, the governing equations are derived and the critical buckling loads under axial compression are obtained. The TWCNTs are considered as three nanotube shells coupled through the van der Waals interaction between them. The results show that the critical buckling load can be overestimated by the local beam model if the small-scale effect is overlooked for long nanotubes. In addition, a significant dependence of the critical buckling loads on the chirality of zigzag carbon nanotube is confirmed, and these are then compared with: A single-walled carbon nanotubes (SWCNTs); and Double-walled carbon nanotubes (DWCNTs). These findings are important in mechanical design considerations and reinforcement of devices that use carbon nanotubes.

Preparation and Electrochemical Properties of Flow-Through TiO2 Nanoarray

Abstract: Microstructure-tailored TiO2 nanoarrays with adjustive wall-hole morphology have been designed to improve electrochemical properties. Tubular, porous and flow-through TiO2 nanoarrays are fabricated by one-stepped, two-stepped and three-stepped anodization process under the controlled reaction condition. Tubular nanoarray with the opened-mouth and closed-bottom has a tube diameter of 120-130nm, a length of 8.12μm, and wall thickness of 15nm. Similarly, porous TiO2 nanoarray with the opened-mouth and closed-bottom has a pore diameter of 60-70nm, a length of 8.25μm, neighboring wall distance of 70-80nm. Comparatively, flow-through TiO2 nanoarray with the opened-mouth and opened-bottom has a pore diameter of 110-120nm, a length of 8.56μm, neighboring wall distance of 40nm. In comparison with tubular and porous TiO2 nanoarrays, flow-through TiO2 nanoarray indicates the deceased charge transfer resistance and diffusion-related Warburg impedance, presenting the enhanced current response at the same electrode potential. Accordingly, bottom-opened flow-through TiO2 nanoarray achieves the specific capacitance of 6.35 mF cm-2, which is higher than the bottom-closed tubular and porous TiO2 nanoarrays (2.94 and 3.78 mF cm-2). The flow-through TiO2 nanoarray presents the improved electrochemical performance for the electrochemical energy-storage.

Multi-Objective Optimization of Magneto Rheological Abrasive Flow Nano Finishing Process on AISI Stainless Steel 316L

Abstract: In this experimental work, Magneto rheological abrasive flow nano finishing processes were conducted on AISI Stainless steel 316L work pieces that are widely used in medical implants. The focus of the present study is to assess the effect of input variables namely the volume percentage of iron (Fe) particles, silicon carbide (SiC) abrasive particles in the Magneto rheological abrasive fluid and number of cycles on the final surface roughness at nano level as well as the material removal rate. The volume % of Fe particles were taken as 20, 25 and 30 and the volume % of SiC particles were taken as 10, 15 and 20. The different number of cycles considered for the study is 100,200 and 300. There are 20 different set of experiments with different combinations of input variables mentioned have been carried out based on the experimental design derived through central composite design technique. The minimum surface roughness observed is 23.34 nanometer (nm) from the initial surface roughness of 1.92 micro meter (µm). Towards optimizing the input process variables, a multi objective optimization was carried out by using response surface methodology.

Effect of Microstructure and Surface Energy on the Static and Dynamic Characteristics of FG Timoshenko Nanobeam Embedded in an Elastic Medium

Abstract: This paper presents an investigation of the size-dependent static and dynamic characteristics of functionally graded (FG) Timoshenko nanobeams embedded in a double-parameter elastic medium. Unlike existing Timoshenko nanobeam models, the combined effects of surface elasticity, residual surface stress, surface mass density and Poisson’s ratio, in addition to axial deformation, are incorporated in the newly developed model. Also, the continuous gradation through the thickness of all the properties of both bulk and surface materials is considered via power law. The Navier-type solution is developed for simply supported FG nanobeam in the form of infinite power series for bending, buckling and free vibration. The obtained results agree well with those available in the literature. In addition, selected numerical results are presented to explore the effects of the material length scale parameter, surface parameters, gradient index, elastic medium, and thickness on the static and dynamic responses of FG Timoshenko nanobeams.

Forced Axial Vibration of a Single-Walled Carbon Nanotube Embedded in Elastic Medium under Various Moving Forces

Abstract: The dynamic free and forced axial vibrations subjected to moving exponential and harmonic axial forces of a single-walled carbon nanotube (SWCNT) embedded in an elastic medium, are studied in this paper. Two different boundary conditions of SWCNT, including clamped-clamped and clamped-free, are taken into account. Eringen’s nonlocal elasticity theory is used to show the nonlocality for the model. The constitutive equations and their boundary conditions are derived by Hamilton’s principle. Employing the general solution, the derived equations are analytically solved to obtain two items. Firstly, the axial natural frequencies, secondly, the time-domain axial displacements at the middle of the carbon nanotube (CNT), and then the maximum axial displacements. The responses are validated with previous works, and the results demonstrates good agreement to them to verify the influence of the nonlocal parameter on the nondimensional natural frequencies for three various mode numbers. In the time-domain section, the effects of the nonlocal parameter, length, nondimensional stiffness of the elastic medium, and velocity of the moving load on the axial displacement are investigated. Also, the influences of the excitation frequency to natural frequency for the harmonic moving load, as well as the time constant for the exponential moving load on the axial displacement, are illustrated. Finally, the effect of the nonlocal parameter on the maximum axial deflection versus velocity parameter is schematically indicated.

Vertical Cavity Surface Emitting Lasers as Sources for Optical Communication Systems: A Review

Abstract: Next generation integrated photonic circuits will be dominated by small footprint devices with lower power consumption, low threshold currentsand high efficiencies. Vertical Cavity Surface Emitting Lasers (VCSELs) having those attractive qualities has shown results to meet the next generation demands for optical communication sources. VCSELs applications are sensors, data com, optical communication, spectroscopy, printers, optical storage, laser displays, atomic optical clocks, laser radar, optical signal processing to name a few. This review centres around on the basic operation of semiconductor lasers, structure analysis of the devices and parameter optimisation for optical communication systems. This paper will provide comparisons on growth techniques and material selection and intends to give the best material realisation for nano optical sources that are up to date as used in optical communication systems. It also provides summarised improvements by other research groups in realisation of VCSELs looking at speeds, efficiency, temperature dependence and the device physical dimensions. Different semiconductor device growth methods, light emitting materials and VCSELs state of art are reviewed. Discussions and a comparisons on different methods used for realising VCSELs are also looked into in this paper.

Structural, Optical, Photocatalytic and Electrochemical Studies of PbS Nanoparticles

Abstract: Oleic acid (OA) and octadecylamine (ODA) capped lead sulphide (PbS) nanoparticles were prepared at 150, 190 and 230 °C. X-ray diffraction patterns indicates that the synthesized PbS nanoparticles were in the rock cubic salt crystalline phase. The particle sizes of the as-prepared PbS nanoparticles are in the range 2.91–10.05 nm for OA-PbS(150), 24.92–39.98 nm for ODA-PbS(150), 9.26 – 29.08 nm for OA-PbS(190), 34.54 – 48.04 nm for ODA-PbS(190), 17.96–88.07 nm for OA-PbS(230) and 53.60 – 94.42 nm for ODA-PbS(230). SEM images revealed flaky and agglomerated spherical like morphology for the nanoparticles. The energy bandgap of the PbS nanoparticles are in the range 4.14 – 4.25 eV, OA-PbS(230) have the lowest bandgap of 4.14 eV while ODA-PbS(150) have the highest bandgap of 4.25 eV. The PbS nanoparticles were used as photocatalyst for the degradation of Rhodamine B and OA-PbS(150) showed efficiency of 44.11% after 360 mins. Cyclic voltammetry of the PbS nanoparticles showed a reversible redox reaction and linear Randles-Sevcik plots indicates electron transfer process is diffusion controlled.

The Vibration of Nano-Beam Subjected to Thermal Shock and Moving Heat Source with Constant Speed

Abstract: This paper deals with a mathematical model of thermoelastic rectangular nano-beam, which is thermally loaded by thermal shock and subjected to moving heat source with constant speed. The nano-beam has been clamped-clamped and its length along the x-axis. The governing equations have been written by using the Euler–Bernoulli equation of nano-beams and the non-Fourier heat conduction with one-relaxation time. Laplace transform has been applied with respect to the time variable, and the solutions have been derived in its domain. The numerical solutions for the Silicon material have been done by using Tzou method. The results have been shown in figures for the temperature increment and the lateral deflection with various values of heat source speed to stand on its effects. Moreover, the effects of the ratio between the length and the width of the beam have been discussed. The speed of the heat source and the dimensions of the beam have significant effects on the temperature increment and the lateral deflection of the beam.

Growth and Characterization of Nanostructured Ag-ZnO for Application in Water Purification

Abstract: In this work, a low-cost method to produce ZnO nanostructured materials for the treatment of water polluted with model organic pollutants (e.g. dyes) is presented. Zinc and silver-coated Zn (Ag/Zn) films, fabricated via sputtering method were naturally oxidized via a simple, low-temperature, scalable thermal process. During oxidation, Ag/ZnO nanorods were grown on Zn foils after treating their surface with various agents (e.g. acids) and annealing in an oven at temperatures 385-400 °C. The ZnO and Ag/ZnO films on Zn were characterized by X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy. The cationic dye Methylene Blue (MB) was selected as model pollutant dissolved in water, and a batch photo-reactor was fabricated and used to to study the adsorption capacity and photocatalytic performance of films. The transient varation of MB concentration in aqueous solutions was measured with UV-Vis spectroscopy. Ag/ZnO demonstrated a strong MB adsorbion capacity in dark conditions, and a satisfactory MB photocatalytic degradation under UV light irradiation.The optimized doping of Ag in Ag/ZnO film enhanced its photocatalytic activity, and seems well-promising for the potential scale-up of Ag/ZnO films, and use in large-scale systems for water purification under UV light irradiation.

Hydrophobic Zinc Oxide Nanocomposites for Consolidation and Protection of Quartzite Sculptures: A Case Study

Abstract: Quartzite sculptures are considered some of the most impressive and informative archaeological remains which have been found in the most of Egyptian archaeological sites. Regrettably, quartzite sculptures suffer from many deterioration aspects such as granular disintegration, scaling, cracking, efflorescence, soiling, microbiological colonization. Water is the main aggressive deterioration factor of stones and stone-based monuments, as in addition to its direct role in deterioration mechanisms, it plays as a catalyst in the physicochemical and microbiological deterioration processes.During the last two decades, polymer nanocomposites have widely been applied in the field of cultural heritage conservation due to their unique physical and chemical characteristics. Zinc oxide nanoparticles are among the most important semiconductive nanomaterials that have been applied in the fabrication of nanocomposites. They have been demonstrated to improve the physicochemical and mechanical properties of polymers. In addition, zinc oxide nanoparticles were mixed with polymers in order to fabricate superhydrophobic and self-cleaning protective materials.The aim of this paper is to evaluate the efficiency of zinc oxide nanocomposites, in order to select the best of them for the consolidation and protection of a colossal quartzite statue of Ramesses II. The properties of the treated quartzite samples were comparatively examined by colourimetric measurements, static water contact angle, compressive strength, and scanning electron microscope.

Facile Synthesis of Fe3O4 Nanoparticles Loaded on Activated Carbon Developed from Lotus Seed Pods for Removal of Ni(II) Ions

Abstract: In this study, a simple one-step synthetic approach using lotus seed pods and iron(III) chloride has been developed to prepare Fe3O4 nanoparticles loaded activated carbon composite (Fe3O4-NPs/AC) for removal of Ni(II) ions from aqueous solution. The physical and chemical characteristics of Fe3O4-NPs/AC were comprehensively analyzed by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometry, and Brunauer–Emmett–Teller analysis. On account of the combined advantages of lotus seed pod carbon and Fe3O4 nanoparticles, the Fe3O4-NPs/AC showed excellent adsorption efficiency for Ni(II) ions with the maximum adsorption capacity of 50.72 mg g-1 at optimal conditions (pH of 6, contact time of 60 min, 25 °C, and adsorbent dosage of 4.0 g L-1). It was found that the adsorption process of Ni(II) on Fe3O4-NPs/AC was feasible, spontaneous and endothermic, and was well described by the Langmuir isotherm model and pseudo-first-order kinetic equation. The Fe3O4-NPs/AC composite also showed good reusability with removal efficiency of greater than 86.25% after five cycles of reuse.

Influence of Alkalinity on the Synthesis of Zeolite A and Hydroxysodalite from Metakaolin

Abstract: Kaolin is a cheap and abundant source of silica and alumina, which may be used as precursors for the production of zeolites, molecular sieves with pores in the nanometer scale. Brazil, one the largest producers of kaolin, generates tons of kaolin waste in the paper coating process. That waste may be used to synthesize zeolite A and hydroxysodalite, greater added value materials with a wide range of applications. In this work, Zeolite A and hydroxysodalite were synthesized from kaolin waste of processing industries for paper coating. Kaolin was calcined to dehydroxylate kaolinite and obtain metakaolin, an amorphous material with Si/Al ratio equal to 1, being suitable for production of zeolite A and hydroxysodalite. Zeolites were synthesized under static hydrothermal conditions by reacting metakaolin with NaOH solutions of different concentrations. The zeolitic products were characterized by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The results showed that the higher the NaOH concentration in the reaction medium, the higher the proportion of hydroxysodalite in the zeolitic samples.

Effect of External Moving Torque on Dynamic Stability of Carbon Nanotube

Abstract: In nano-dimension, the strength of the material is considerable, and the failure is unavoidable in a torsional mode. Because of this reason, the free and forced torsional vibrations of single-walled carbon nanotube (SWCNT) are investigated in this paper. For dynamic analysis, the moving harmonic torsional load is exerted to SWCNT. The related boundary condition and equation of motion are derived by Hamilton’s principle, and the equation is discretized by the Galerkin method. In order to demonstrate the nonlocality and small–scale effect, Eringen’s theory based on nonlocal elasticity theory is applied. A clamped-clamped (C-C) boundary condition is fitted for the end supports. The influences of the aspect ratio and mode number on the free natural frequency are investigated. Furthermore, the dynamic effects of nonlocal parameter, velocity, thickness, length, and excitation-to-natural frequencies on dimensional and nondimensional angular displacements are indicated. Moreover, the natural frequency was investigated due to the variation of the aspect ratio.

Free Vibration Analysis of Functionally Graded FG Nano-Plates with Porosities

Abstract: This study presents the analytical solutions of free vibration analysis of simply supported nanoplate FG porous using nonlocal high order shear deformation plate theory. This theory contains four unknowns without the use of shear correction factors unlike the others. The objective of this article is to develop a model to use the function f (z) on vibration and the natural frequencies of functionally graded nanoplates nonlocal to study the effect of the various parameters. The validity of the theory is shown by comparing the present results with obtained with those reported in the literature. The effects of various parameters are all discussed.

Effect of Solution Concentration on ZnO/ZnAl2O4 Nanocomposite Thin Films Formation Deposited by Ultrasonic Spray Pyrolysis on Glass and Si(111) Substrates

Abstract: A complex ZnO/ZnAl2O4 heterostructures thin films on glass and Si (111) substrates have been successively obtained by a soft ultrasonic spray pyrolysis (USP) method deposition using the Zn/Al molar ratios concentrations of 0.07/0.13 and 0.1/0.1, respectively. According to (XRD) an ordered zinc oxide (ZnO) and zinc aluminate (ZnAl2O4) structures deposited onto glass from the air annealing at 500 °C during 2 hours was observed and confirmed by the (EDX), (FTIR) and Raman spectroscopy techniques. The estimated crystallites size and stress values of ZnO and ZnAl2O4 in the ZnO/ZnAl2O4/glass film were 19 nm/0.469 GPa and 11 nm/-0.292 GPa, respectively. The lower Zn/Al molar ratio around 0.035/0.06 produced only ZnO as a single phase, suggesting the Al insufficient quantity. The Si (100) substrate with 0.07 Zn molarity conducted to the Zn2SiO4/ZnO/ZnAl2O4 composite. The Raman integrated intensity bands of ZnO and ZnAl2O4 increases with increasing Zn to Al molar ratio (0.1/0.1 comparatively to 0.07/0.13). The ZnO&ZnAl2O4 crystallinity enhances as Zn molarity increases. The ZnO films in the composites grow with (002) texture. The TC(hkl) value indicated that ZnAl2O4 in the ZnO/ZnAl2O4/glass layer is polycrystalline preferentially oriented along the (311) plane. Spinel ZnAl2O4 oxide onto Si (111) substrate grown according to the (220) orientation. Crystallites are larger in ZnO/ZnAl2O4/Si than in ZnO/ZnAl2O4/glass. The ZnO/ZnAl2O4 film onto glass substrate is transparent in the visible and near infrared regions and sensitive to UV absorption, as characterized by UV-Vis spectroscopy. The ZnO and ZnAl2O4Egvalues in the ZnO/ZnAl2O4/glass composite were 3.25 and 3.88 eV, respectively.

Quantum Mechanical Analysis on Modeling of Surface Potential and Drain Current for Nanowire JLFET

Abstract: This paper presents an analytical model for ultra scaled symmetric double gate (SDG) nanowire junctionless field effect transistor (JLFET), which includes charge quantization in all the regions of operation. This model is based on a first-order correction for the confined energies obtained by solving the Schrodinger’s equation. The model is able to predict the quantum mechanical effects (QME) on the surface potential, drain current and transconductance for a highly doped and extremely thin silicon layer of thickness down to 4nm. The results obtained are validated by comparing with GENIUS 3D TCAD quantum simulations.

Comparative and Experimental Studies for Evaluation of Paraloid B-72 in Traditional and Nano Forms for Joining of Pottery Samples

Abstract: Many of the excavated pottery artifacts are suffering from different deterioration aspects. The pressure of burial environment is considered the most deteriorative agent for pottery in soil, which leads to damage of the artifact. Therefore, it is necessary to join these damaged parts to be suitable for museum display. The adhesive materials play a significant role in the joining processes of these artifacts. In this study, Paraloid B-72 in its traditional and nano form was prepared (50% in acetone) as adhesive for pottery artifacts. Twelve pottery tiles (14 ×4×1 cm) were prepared and then were adhered together with the adhesive in traditional and nano forms. The pottery samples were exposed to artificial aging as follows; accelerated heat-humid aging (temperature 100°C and 60% relative humidity) and light aging by U.V lamp for 100 hours. Visual assessment and several analytical techniques were used for the evaluation of the selected adhesive. The analytical techniques are transmission electron microscope (TEM), scanning electron microscope (SEM), color change and tensile strength. The results obtained from transmission electron microscope showed that grain size of nano paraloid was ranging from 33 to 51 nm where the particle size of the traditional paraloid was in the range between 103 to 150 nm. Visual assessment proved that nano paraloid had some simple changes in appearance. Scanning electron microscope revealed that the nano paraloid was more resistance for aging than traditional form. Color change revealed that nano paraloid gave the lowest level of total color differences (ΔE) after light, heat-humid and light-heat aging with 2.31, 3.26 and 4.60 respectively. The tensile strength revealed that nano paraloid gave highest tensile strength (81.3 N/mm2). According to these results, we recommend the use of nano paraloid in joining of archaeological pottery artifacts.

Simulation of Crystalline Phase Formation in Titanium-Based Bimetallic Clusters

Abstract: In this work, we simulated and analysed phase transformations in the structure of nanosized bimetallic titanium-containing clusters during the cooling process. The results demonstrate the predominantly α+β crystalline structure of the TiAl nanoalloy after cooling, and the TiV nanoalloy has an amorphous structure. The glass transition temperatures for bimetallic systems TiAl and TiV for various compositions were determined.

Study of Mn doping on the Structural, Optoelectronic and Photoluminescence Properties of F-Doped SnO2 Sprayed Thin Films for Optoelectronic Applications

Abstract: The aim of this work is the production and the characterisation of (SnO2: (Mn, F)) thin films with appropriate optoelectronic properties required for application as ohmic contacts in photovoltaic application devices. Transparent conducting Manganese-fluorine co-doped tin oxide (SnO2: (Mn, F)) thin films have been deposited onto preheated glass substrates using the chemical spray pyrolysis (CSP) method. The ([Mn2+]/[Sn4+]) atomic concentration ratio (y) in the spray solution is varied between 0 and 8 at. %. The structural, the opto-electrical and the photoluminescence properties of these thin films have been studied. It is found that the deposited thin films are polycrystalline with a tetragonal crystal structure corresponding to SnO2 phase having a preferred orientation along the (200) plane. Transmission and reflection spectra reveal the presence of interference fringes indicating the thickness uniformity and the surface homogeneity of the deposited samples. Photoluminescence behaviour of Mn-F co-doped SnO2 thin films was also studied. Photoluminescence spectra reveal the presence of the defects like oxygen vacancies in the materials. In addition, The electrical resistivity, volume carrier concentration, surface carrier concentration and electrical mobility were determined from Hall Effect measurements and the following results were obtained: n-type conductivity in all the deposited thin films, a low resistivity of 1.50×10-4 Ω cm, and a high electrical mobility of 45.40 cm2 V-1 s-1 with Mn co-doping concentration equals to 7 at. %. These experimental results show that the electrical properties of these thin films where greatly improved making them suitable as ohmic contacts in photovoltaic applications devices.

The Effect of Vapor Transport Annealing on FeSe Films Deposited on 2D Material

Abstract: Owing to its simple crystal structure, tetragonal FeSe has been considered as a perfect candidate for investigating the interplays among the superconductivity, magnetism and structural phase transition. Previous works had revealed that superconductivity could only be seen in samples with Se deficiency for the otherwise ferromagnetic tetragonal FeSe. In this study, we investigated the effect of vapor transport annealing on the crystalline quality of FeSe films deposited on flexible muscovite (mica) substrates by pulsed laser deposition. The annealing processes were conducted by sealing FeSe powder in tandem with the as-deposited FeSe films in a quartz tube. The FeSe powder was placed at a distance of about 18.5 cm from the FeSe films and the entire sealed quartz tube (about 1.2 cm in diameter) assembly was put into a Lindberg three-zone furnace and maintained a temperature gradient between the two ends of the quartz tube. The results showed that FeSe films successfully grown on flexible mica substrates and the annealing did improve the morphology and crystallinity of the films, however, the films appeared to have more inhomogeneous phases. We suspect that this might be due to uncompleted FeSe phase nucleation in non-optimum condition. The interface between the muscovite substrate and the FeSe films also could be the caused of the formation of other impurity phases, such as FeSe2 and Fe3Se4. Consequently, the obtained films exhibited only paramagnetic behaviors, and there was no sign of zero-resistance down to 2 K.

The Differentially Effect of Some Antilipid Drugs on Activity of the Novel Synthesized Paraoxonase (PON1)-Inorganic Hybrid Nanoflowers

Abstract: In the present study, the hybrid nanoflower PON1-Ca2+ (hNF-PON1) structure was synthesized and characterized and some antilipid drugs effects were investigated on hybrid paraoxonase (PON1) activity. Firstly, the hPON1 enzyme was purified 304.5 fold with 76.4% yield from human serum using the triple phase separation technique (TPP). Then, the hNF-PON1 was prepared in a one-step procedure using biomimetic mineralization. The catalytic activity of the hybrid enzyme with an 88.49% binding rate increased by 26.40%. The characterization of hNF-PON1 structure was performed with SEM, TEM, EDX, FT-IR and XRD analyzes. The effects of some lipid-lowering drugs (Valeric acid, phenoxy – isobutyric acid, N-desmethyl rosuvastatin) were also investigated on the activity of hNF-PON1 enzyme. When the re-usability of the enzyme was tested 10 times in succession, the enzyme was determined to protect the activity by 60%. Inhibition kinetics (IC50 and Ki values) of hybrid structure was determined. In the last stage of the study, the potential toxic effect of hNF-PON1 structure was evaluated using zebrafish embryos. To this end, zebrafish embryos were exposed to hNF-PON1 with 50-2000 ppm concentrations and monitored at 24, 48, 72 and 96 hpf. Survival rate, hatching rate and body malformations were evaluated during this period and it was determined that the hNF-PON1 structure did not exhibit any toxicity on zebrafish embryos.

Thickness Effect of Zno Film on the Performance of Photocatalytic in a p-Nio/n-Zno Heterostructure under Solar Light Irradiation

Abstract: In this work, we studied the ZnO film thickness effect on the photocatalytic performance of n-ZnO/p-NiO heterostructures. The ZnO and NiO films were prepared by sol-gel dip-coating technique and the thickness of the ZnO film was varied by changing the number of coatingsfrom 2 to12. The formation of the p-NiO/n-ZnO heterostructure was confirmed by X ray diffraction (XRD). The obtained ZnO films present a wurtzite structure with a preferred orientation along (002) direction while the NiO film present a cubic structure highly oriented along (200) direction. UV-visible transmittance spectra of the prepared heterostructures revealed a good transparency in the visible region. The photocatalytic propertiesof the n-ZnO/p-NiO heterostructures were investigated by measuring the degradation rate of methylene blue. All the samples exhibit a good photocatalytic activity under solar light irradiation. The photocatalytic activity of p-NiO/n-ZnO heterostructureswas strongly correlated with the number of ZnO coatings. The highest photocatalytic activity was obtained at 6 coatings with a degradation rate of methylene blue equal to 98.67% for 4.5h of irradiation.

Fabrication of Room Temperature Resistive Ethanol Gas Sensor Based on ZnO Nanorods Decorated with PbS Nanoparticles

Abstract: A resistive ethanol gas sensor with a high sensitivity has been proposed. The fabricated gas sensor has a very promising response and recovery at room temperature. The proposed sensor has been fabricated by depositing sensitive nanostructured material on printed circuit board interdigitated electrodes. As the sensitive material, ZnO nanorods of high uniformity have been synthesized by hydrothermal method and then decorated by PbS nanoparticles. The synthesized decorated nanorods were characterized by X-ray diffraction and scanning electron microscope which confirmed the formation of the desired nanostructures. The ethanol gas sensing properties of the ZnO nanorods decorated with PdS nanoparticles was measured in a test chamber. The minimum ethanol concentration detected by the sensor has been 10 ppm. The results showed the higher sensitivity of the proposed sensor to the ethanol at room temperature compared to similar works.

Synthesis of Gold Nanorods by Using H2O2 as the Weak Reducer in a Binary Surfactant Mixture

Abstract: A new seed-mediated growth technique for synthesizing gold nanorods (NRs) by using H2O2 as the weak reducer in the presence of a binary surfactant mixture is reported. Gold NRs prepared at different amounts of H2O2 and the gold seeds solution were characterized by transmission electron microscopy (TEM) and visible–near infrared spectroscopy. Gold NRs with tunable aspect ratio from 4.5 to 7 can be obtained and the corresponding longitudinal plasmonic wavelength of the produced gold NRs are tunable from 810 to 1140 nm. This method provides a new pathway for synthesis of gold NRs with a wide range of longitudinal plasmonic peaks, which have potential applications in optoelectronics and biomedicine.

Numerical Study of Long Channel Carbon Nanotube Based Transistors by Considering Variation in CNT Diameter

Abstract: While much numerical studies have been done on short channel carbon nanotube field effect transistors (CNT-FETs), there are only a few numerical reports on long channel devices. Long channel CNT-FETs have been widely used in chemical sensors and biosensors as well as light emitters. Therefore, numerical study is helpful for a better understanding of the behavior of such devices. In this paper, we numerically analyze long-channel CNT-FETs by solving the continuity and charge equations self-consistently. To increase the accuracy of simulation, filed-dependent mobility is applied to the equations. Furthermore, a method is proposed to obtain the electrical current of transistors as a function of CNT diameter. Obtained results are in good agreement with the previous experimental data. It is found that compared to a CNT-based resistor, the dependence of current on diameter is much higher in a CNT-FET. Finally, reproducibility of transistors based on the arrays of random CNTs of 1-2 nm diameter in terms of the CNTs number is also investigated.

Effect of Gate Engineering and Channel Length Variation in Surrounding Gate MOSFETs

Abstract: In this paper, the digital and analog performance for Double Material Gate Surrounding Gate Metal Oxide Semiconductor Field Effect Transistor (DM SG MOSFET) has been analyzed. A detailed study of DM SG MOSFET is performed for different channel length ratio's. The comparison analysis on surface potential, electric field, transfer characteristics, output characteristics, transconductance and output conductance is carried with respect to the silicon dioxide and hafnium dioxide based device. It has been found from the simulation results that HfO2 dielectric used DM SG TFET provides better performance than SiO2 dielectric used DM SG TFET. Also it has been observed from the presented results that the transconductance is 45.32 at 1:3 channel length ratio for DG SG MOSFET.

The Effect of Graphene Oxide Dispersion on Structure-Property Relationships in Graphene-Based Polymer Nanocomposites

Abstract: The performance of graphene/polymer nanocomposites depends on many factors but the major factor is a nanoparticles dispersion and distribution into the host matrix. The present work investigates the effect of the dispersion of graphene oxide upon the structure-property relations in metallocene linear low density polyethylene (PE), homo polypropylene (PP), and blends thereof. These nanocomposites were prepared by solvent processing, where DMF and o-xylene were used as solvents for Graphene Oxide (GO) powder and the polymers respectively, before the two components were combined to form a well-mixed initial state. Characterization of the structure and crystallization of the nanocomposites was carried out by small- and wide-angle X-ray scattering and diffraction (SAXS and WAXD). The chemical structures were characterized by Fourier transform infrared spectroscopy (FTIR) and by Raman spectroscopy, and the latter used to calculate the ID/IG value for a pure GO samples. The thermal properties of the resulting nanocomposites were investigated by DSC and TGA in order to obtain Melting temperature ( ), crystallization temperature ( ) and degree of crystallinity ( ) as well as a range of degradation temperatures. The effect of GO on the mechanical properties was studied via the ultimate tensile strength and elastic modulus.

Synthesis, Structure, Optic and Photocatalytic Properties of Anatase/Brookite Nanocomposites

Abstract: Anatase/brookite nanocomposites were fabricated by the classical method of hydrolysis, additionally using hydrothermal treatment of preformed titanium dioxide sol with tetrabutyl orthotitanate. The influence of hydrothermal processing the buffer solution of TiO2 synthesis on the average particle sizes, specific surface area, pore sizes distributions, optical and photocatalytic properties investigated by X-ray diffraction, low-temperature nitrogen adsorption and UV-Vis spectroscopy. It has been determined that the hydrothermal treatment of pre-prepared titania sol as hydrolysis product leads to rutile formation after annealing at 400°C. Respective model of forming anatase/brookite/rutile nanocomposites was proposed. The changes of bang gap energy of TiO2 were observed and explained by effect of change phase composition and particles size of nanocomposite particles. Methylene blue (MB) photo-oxidation reactions using titanium dioxide nanocomposite were analyzed. Maximal photocatalytic activity of MB oxidation was detected for material with the ratio of the titania phases (anatase : brookite : rutile – 2 : 2 : 1). Synergistic effect between crystallinity, phase ratio, morphology of oxide material, band gap and photocatalytic activity in the anatase/brookite nanocomposites was established.

Structural, Optical and Electrical Properties of ZnxSn1-xS Thin Films Deposited by Chemical Spray Pyrolysis

Abstract: In the present study, ZnxSn1-xS (x = 0, 0.25, 0.5, 0.75 and 1) thin film samples were deposited by ultrasonic spray pyrolysis technique on glass substrates at 350°C to investigate the effect of variation of Zn concentration (x) on the structural, morphological, optical and electrical properties of ZnxSn1-xS thin films. The films were deposited by varying Zn content in the starting solution. The films deposited were found to be amorphous having root mean square (RMS) roughness ranged from 18.2 to 93.5 nm. The optical characterization by UV-Vis spectroscopy showed that the transmittance and reflectance of all samples are lower than 12.2 % and 10 % respectively. The optical band gap was estimated from the reflectance and transmittance spectra are about 3.86 eV. The carrier mobility is ranged from 113 to 2600 cm2/v.s.