Journal of Nano Research Vol. 56

Abstract: A promising rotating arc discharge method has been developed for producing high purity silver carbon nanotube and zinc oxide nanoparticles, to study their capacities for methylene blue (MB) dye removal under different conditions such as contact time, initial methylene blue dye ion concentration, solution pH, and adsorbent dose. The equilibrium isotherm data were analyzed using Langmuir, Freundlich, Temkin isotherms. Correlation coefficients indicated the following order to fit isotherms for silver carbon nanotube: Freundlich > Langmuir > Temkin. On the other hand, for zinc oxide nanoparticles, the following adjustment founded to fit isotherms was: Langmuir > Temkin> Freundlich. Furthermore, separation factors and distribution coefficients of Methylene blue (MB) dye were calculated. Adsorption kinetic data were analyzed using pseudo-first and second -orders and Elovich model. Film and intraparticle Diffusion model were used to investigate Adsorption mechanism. Kinetic studies showed that the adsorption of methylene blue onto silver carbon nanotubes followed Elovich kinetic model, and the rate of adsorption is controlled by the liquid film diffusion model. Adsorption of methylene blue on zinc oxide nanoparticles followed the pseudo-second-order kinetic model, and the rate of adsorption is controlled by the intraparticle diffusion model.

Abstract: In this work, nanosized calcium deficient hydroxyapatite (nCDHA) was synthesized by the precipitation method, and then utilized as an adsorbent for removal of Fe (II), Cu (II), Ni (II) and Cr (VI) ions from aqueous solutions after characterizing it by various techniques as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and BET method. A possible structure of synthesized nCDHA was proposed. The adsorption study indicated that the adsorption equilibrium is well fitted with Langmuir isotherm model with the maximum adsorption capacities followed the order of Fe (II) > Cu (II) > Ni (II) > Cr (VI) with the values of 137.23, 128.02, 83.19 and 2.92 mg/g, respectively. The ion-exchange mechanism was dominant for the adsorption of metal ions onto nCDHA at initial metal concentrations lower than 0.01 mol/L. Along with the ion-exchange mechanism, there was an additional precipitation occurred on the surface of nCDHA in the case of Fe (II) and Cu (II) at initial concentrations higher than 0.01 mol/L.

Abstract: TiO₂ and iron-doped TiO₂ were synthesized by sol-gel method. TiO₂ and 0.5 %mol Fe:TiO₂ were calcined at 500 and 800 °C for 3 h. The synthesized particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-VIS diffuse reflectance spectrophotometry (UV/DRS), scanning electron microscopy (SEM) and scanning electron microscope-energy dispersive X-Ray analysis (SEM-EDX). The XRD patterns of all samples that were calcined at 500 °C showed only anatase phase. On increasing temperature from 500 to 800 °C, the anatase phase transformed to rutile phase. For 0.5 %mol Fe:TiO₂, pseudobrookite (Fe₂TiO₅) phase was observed at 800 °C. The particles that contained rutile showed higher antibacterial activities against E. coli, B. subtilis, and S. aureus than anatase phase, under fluorescent irradiation.

Abstract: Egyptian faience is one of the most important archaeological materials that contain a lot of historical and technical information about ancient Egyptian civilization. Unfortunately, the Egyptian faience objects subject to many deterioration factors, especially humidity. Water has a direct role in dissolving the soluble components, it accelerates the physiochemical deterioration processes. In the present study, four types of ready to use nanoproducts were evaluated. It was done to select the best of them to consolidate and protect some archaeological faience from Matteria magazine. The properties of the treated samples, were comparatively investigated by colormetric measurements, static water contact angle, total immersion water absorption, compressive strength, and scanning electron microscope.

Abstract: Zinc oxide (ZnO) and Zinc peroxide (ZnO₂) nanoparticles were synthesized by colloidal method at low temperature. The thermal stability of ZnO₂ was studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-Ray diffraction (XRD). The crystalline structure and phase change from ZnO₂ to ZnO by heat treatment was studied in detail. Morphology and particle size was examined using Transmission Electron Microscopy (TEM), for as synthesized ZnO and ZnO₂ the shape of particles were cuasi-spherical for both materials with average size of 10±2.2 nm and 2.5±0.4 nm, respectively; The crystal size for ZnO obtained by heat treatment was 8±2.2 nm. Electron density contours show the chemical bond type ionic and covalent for ZnO and ZnO₂. The vibrational properties were analyzed by Raman and IR spectroscopy. Band gap values were obtained from ultraviolet-visible (UV-Vis) absorbance spectrum. Photoluminescence (PL) spectrum for ZnO shows two emission edges located at 445 and 492 nm and in the case of ZnO₂ presents one edge at 364 nm originated from the band edge emission. The optical spectra present a hypsochromic shift, compared with some reported in the literature.

Abstract: In this paper, a non-Newtonian fluid was fabricated dispersing nanosized silica particles in a polyethylene glycol medium. The rheology of the suspension was investigated in a stress-controlled rheometer under increasing shear rate. Based on the rheological measurements, the suspension exhibited shear thickening behavior which gives a drastic viscosity grow with the increase in the shear rate. In order to investigate the role of the micro-sized additive particles on the rheology of silica based suspension, silicon nitride particles were included in the suspension with three different concentrations. The results were discussed in terms of important parameters for the shear thickening mechanism such as critical shear rate, peak viscosity, thickening ratio and initial viscosity. According to the results, shear thickening behavior can be controlled altering the amount of silicon nitride particles in the suspension.

Abstract: This paper describes the analytical modeling and simulation of Triple Material Double Gate Metal Oxide Semiconductor Field Effect Transistor (TMDG MOSFET) with no junctions. Three kind of gate materials with different work function values over the channel helps to improve the ON current and to form a barrier in the channel helps to reduce OFF current. It has been found from the obtained results that the OFF current or leakage current of the device is exactly low (I_OFF =10^-11 A) which is fit for low power applications. Also, the extracted value of I_ON current (10^-3 A) has proved that there is a remarkable improvement with decreasing device dimensions. The overall gate length (L), work functions of gate materials, oxide thickness (t_ox), silicon thickness (t_si) and doping concentration (N_d) are optimized at 60nm, 4.8eV, 4.6eV, 4.4eV, 1nm, 10nm and 10¹⁹ cm^-3 respectively. The 2-D Poisson equation has been solved by using parabolic approximation technique to obtain the potential distribution function in the channel. Based on this expression, analytical models of the lateral electric field, subthreshold slope and drain current for Junctionless Triple Material Double Gate Metal oxide semiconductor Field Effect Transistor (JL TMDG MOSFET) were derived. Finally, the validity of the proposed analytical model is compared with numerical solution simulation data results which are obtained by using TCAD device simulator.

Abstract: A protein-based electrospun nanofiber from cold water fish gelatin (FG) including bovine lactoferrin (L) as an antimicrobial substance for food packaging applications was developed. Various amounts of L (0, 5, 10, 15, and 20%) were incorporated into FG electrospun nanofibers in order to test antimicrobial activity by disc diffusion method against Pseudomonas fluorescens, Acinetobacter johnsonii, Aeromonas hydrophila, Flavobacterium psychrophilum, Shewanella putrefaciens, and Escherichia coli commonly cause problems in food safety especially in fish products. It was obviously seen that 15% and 20% wt L incorporated FG electrospun nanofibers had significant inhibition zone against all bacterial strains while 5% and 10% L-FG had lower antimicrobial effects. In order to recommend fish gelatin as a food packaging material, mechanical properties should be enhanced to be competitive with synthetic polymers. It was revealed that mechanical strength of gelatin electrospun nanofibers depended on both fiber morphology and bioactive substance content. Neat FG (N-FG ) bead-free electrospun mats had higher fiber diameter (815 ±40 nm) while 15% and 20% L-FG had relatively lower diameter with beaded morphology, i.e., 348 ±32 nm, 229 ± 44 nm respectively. The tensile strength of 20% L-FG mats was significantly lower than the N-FG mats due to beady and thinner morphology. It can be concluded that L-FG electrospun nanofibers with high antimicrobial activity and improvable tensile strength is promising for active packaging applications.Keywords: Electrospinning, Pseudomonas spp., Escherichia coli, Shewanella spp., biodegradable, active packaging

Abstract: NH₃ gas sensor was fabricated based on deposited of Functionalized Multi-Walled Carbon Nanotubes (MWCNTs-OH) suspension on filter paper substrates using suspension filtration method. The structural, morphological and optical properties of the MWCNTs film were characterized by XRD, AFM and FTIR techniques. XRD measurement confirmed that the structure of MWCNTs is not affected by the preparation method. The AFM images reflected highly ordered network in the form of a mat. The functional groups and types of bonding have appeared in the FTIR spectra. The fingerprint (C-C stretch) of MWCNTs appears in 1365 cm^-1, and the backbone of CNTs observed at 1645 cm^-1. A homemade sensing device was used to evaluate the fabrication network toward NH₃ gas at ppm levels as well as the response to sensitivity by changing the concentration. MWCNTs-OH network of 8mm thickness showed an increase in resistance upon exposure to the NH₃ gas. The sensor exhibits a good sensitivity for low concentration of NH₃ gas at room temperature. The sensitivities of the network were 2.5% at 14ppm, 5.3% at 27ppm and 17.6% at 68ppm. Further investigations showed that the network was specific sensitive to NH₃ gas in the environment and not affected by the amount of ambient air.

Abstract: Some years ago a new process was developed for the elaboration of alloys in order to overcome drawbacks observed in samples produced by conventional casting. In the present work are shown the results obtained by high energy mechanical milling for Cu-Al-Ni. the mechanical alloying powder Cu₈₄Al₁₂Ni₄ (W%) was fabricated in high energy planetary ball milling at a speed of 250 r/min for various milling times (10 20 30 40 50 60 hours) the weight ratio of the balls of powder was 15 to 1. this mechanical alloying process is significantly modifying the characteristic of the powder, the recovered grains are ultimately compacted. The means used to study the different evolution are SEM Scaning Electron Microscopy, Differential thermal analysis DTA, X-ray Diffraction analysis and DRX in situ.